Parametric Sensitivity of Settlement Patterns in Tropical Peat: A Comparative Analysis of 1d Theoretical and 2d Numerical Embankment Models

Parametric Sensitivity of Settlement Patterns in Tropical Peat: A Comparative Analysis of 1d Theoretical and 2d Numerical Embankment Models | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Parametric Sensitivity of Settlement Patterns in Tropical Peat: A Comparative Analysis of 1d Theoretical and 2d Numerical Embankment Models Nathrah Hanim Muhamad Nazri, Mohd Khaidir Abu Talib, Siti Nor Hidayah Arifin, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9438122/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Tropical peat deposits present profound challenges for infrastructure due to their extreme compressibility. To eventually determine safe embankment construction heights, it is first necessary to thoroughly understand how specific geotechnical parameters influence primary settlement patterns. This study presents a parametric sensitivity analysis of road embankments over Malaysian tropical peats (fibric, hemic, and sapric). To isolate and understand these behavioral patterns, settlement was evaluated using a theoretical 1D analytical baseline and compared against 2D Finite Element Analysis utilizing the Soft Soil Model (SSM). By systematically varying the compression index, initial void ratio, unit weight, and groundwater levels, the study maps the settlement trajectories. The results demonstrate that for decomposed peats under standard loading, the numerical and analytical patterns align closely, validating traditional 1D consolidation theories. However, significant predictive divergence (up to 21%) is triggered under specific parametric combinations namely, highly fibrous peats with maximum initial void ratios. This gap highlights the exact parametric thresholds where multi-directional stress redistribution and lateral yielding dominate. By mapping these parameter-driven deviations, this study establishes the fundamental behavioral framework required to optimize safe embankment heights in complex peat environments. Tropical peat Finite element modelling Settlement prediction Soft Soil Model Parametric analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 1 Introduction Tropical peat, commonly found in swampy and wetland areas, poses significant challenges in civil engineering due to its unique and problematic geotechnical properties ( Huat et al., 2009 ; Mahyan et al., 2023 ). This organic soil, formed from partially decomposed plant material under high water tables, is characterized by extremely high water content (often exceeding 200% and even reaching up to 2200% in Malaysia), high initial void ratios (typically ranging between 5 and 30), high compressibility, and low shear strength (between 5 and 25 kPa) ( Juha et al., 2018 ; Mohamad, 2021 ; O’Kelly & Pichan, 2013 ; Pakir et al., 2026 ; Wahab et al., 2022 ). These characteristics, along with high porosity and low bulk density, make it very difficult to accurately assess the physical and geotechnical behavior of peat, which can vary significantly based on its location and composition ( Mahyan et al., 2023 ; Meyer & Olszewska, 2021 ; Muroby & Anwar Makarim, 2020 ; O’Kelly & Pichan, 2013 ) . In Malaysia, where approximately 2.4 to 3 million hectares of peatland exist 1.65 million hectares of which are in Sarawak infrastructure development faces serious challenges because of these inherent soil limitations ( Kamaruidzaman et al., 2019 ; Khing, 2016 ; Wahab et al., 2022 ). Constructing on peatlands presents significant geotechnical challenges, including bearing capacity failure, excessive instability, and substantial primary and long-term consolidation settlement ( Muroby & Anwar Makarim, 2020 ; Rasheed & Moghal, 2022 ) . These issues often result in severe structural damage, embankment and slope failure, and serviceability problems such as differential settlement and uneven road surfaces ( Gofar & Sutejo, 2007 ; Ivakhnova & Nevzorov, 2020 ; O’Kelly & Pichan, 2013 ) . Given these risks, accurate prediction of settlement is essential to ensure the structural performance and long-term serviceability of road embankments ( Mahyan et al., 2023 ; Wahab et al., 2022 ). Failure to accurately estimate settlement can lead to costly maintenance, premature infrastructure failure, and violation of design criteria ( Azadnejad et al., 2024 ; Trinh Dinh, 2024 ) . Therefore, reliable settlement prediction is not only a design requirement but also a critical component of sustainable infrastructure development on peat soils ( Murdiyarso et al., 2019 ; Pakir et al., 2026 ). Traditionally, preliminary embankment design over soft soils, including peat, has relied on classical one-dimensional (1D) consolidation theory ( Galaviz-González et al., 2022 ; Jia et al., 2022 ). While widely adopted due to its simplicity, this approach assumes zero lateral strain (K₀ condition) and uniform stress distribution, which oversimplifies the complex behaviour of highly compressible and structured peat soils ( O’Kelly & Pichan, 2013 ; Szczepan Olek, 2019 ) . This assumption becomes mechanically inadequate for fibrous peat deposits subjected to unconfined embankment loading, where significant lateral deformation and multidirectional stress redistribution occur ( Mendoza et al., 2022 ). Consequently, advanced numerical approaches such as two-dimensional (2D) Finite Element Analysis (FEA), particularly using the Soft Soil Model (SSM) in PLAXIS, have become essential ( Himawan et al., 2024 ; Trinh Dinh, 2024 ) . These models are capable of capturing strain localisation, stress redistribution, and progressive stiffening behaviour, providing a more realistic representation of peat response under loading ( Galaviz-González et al., 2022 ; Lechowicz & Sulewska, 2022 ; Tashiro et al., 2015 ). Despite these advancements, a clear quantitative understanding of the divergence between 1D analytical predictions and 2D numerical simulations across varying peat conditions remains limited. Therefore, this study aims to systematically quantify this predictive gap through parametric sensitivity analysis ( O’Kelly & Pichan, 2013 ; Rasheed & Moghal, 2022 ) . Key parameters such as compression index (Cₒ) and initial void ratio (e₀) are evaluated to establish geotechnical thresholds that define the applicability limits of 1D theory and the necessity for advanced numerical modelling ( Kamaruidzaman et al., 2019 ). Ultimately, this framework supports the safe determination of embankment heights and enhances design reliability for peatland infrastructure ( Prihatiningsih & Khohara, 2023 ; Tashiro et al., 2015 ). 2 Methodology 2.1 Data Compilation and Development of the Parametric Database The initial step involved the creation of a comprehensive secondary database detailing the properties of Malaysian tropical peat. This database was essential due to the highly heterogeneous nature of tropical peat deposits, whose mechanical behaviour can vary significantly based on environmental conditions, botanical origin, and fibre composition. The considerable variability in the physical characteristics of tropical peat poses significant challenges for geotechnical engineering. These characteristics can differ greatly across geographical locations due to factors such as temperature, moisture levels, botanical origin, and fibre composition. Peat is classified into three primary categories based on its degree of decomposition: fibric, hemic, and sapric peat. Fibric peat, being the least decomposed, showcases a well-structured fibre network. Hemic peat displays an intermediate level of decomposition, while sapric peat is highly decomposed and exhibits properties more reminiscent of conventional organic soil. Malaysia is home to extensive peat deposits that represent all three decomposition states. The degree of decomposition has a significant impact on peat compressibility, permeability, and long-term consolidation behaviour, with fibric peat typically exhibiting the highest potential for settlement due to its highly porous structure. To ensure that both analytical and numerical models realistically represent field conditions, a secondary database of Malaysian tropical peat properties was developed through the systematic compilation of geotechnical parameters from peer-reviewed journal articles, technical reports, and regional soil investigations. From this compiled dataset, key parameters influencing consolidation behavior were extracted, allowing for the establishment of boundary ranges for a parametric sensitivity analysis. These parameters include initial void ratio, compression index, peat thickness, unit weight, and groundwater level, all of which are well-established as critical variables affecting settlement behavior in peat deposits. The resulting parameter ranges adopted in this study are summarized in Table 1 . Table 1 Geotechnical parameter ranges for Malaysian tropical peat used in the parametric modelling framework Parameter Value Sources Initial Void Ratio (e o ) 5.0–15.0 (Duraisamy et al., 2007 ; Gofar & Sutejo, 2007 ; Gui et al., 2020 ; Himawan et al., 2024 ; Huat et al., 2009 ; Johari et al., 2016 ; Mendoza et al., 2022 ; Muroby & Anwar Makarim, 2020 ; O’Kelly & Pichan, 2013 ; Paul & Hussain, 2020 ; Prihatiningsih & Khohara, 2023 ; Rasheed & Moghal, 2022 ; Sari et al., 2023 ; Yamaguchi et al., 1985 ; Zainorabidin et al., 2024 ) Compression Index (c c ) 0.8–3.15 Peat Depth (D p ) 1.0 m – 20.0 Unit weight peat (γ peat ) 8.0–12.0 Groundwater Level (GWL) 0.2 m – 1.0 m below ground surface. These parameter ranges were used to generate both analytical settlement calculations and numerical modelling scenarios, allowing for a consistent comparison between theoretical predictions and finite element results. 2.2 Analytical Settlement Prediction Using One-Dimensional Consolidation Theory Terzaghi's one-dimensional (1D) consolidation theory serves as a foundational framework for estimating settlement in soil layers subjected to applied loads. This theory, articulated through Eq. 1, primarily addresses the compression that occurs due to the expulsion of water from the voids in saturated cohesive soils, leading to observable changes in volume. It emphasizes that primary consolidation is a time-dependent process driven by the dissipation of excess pore water pressure. As this pore pressure dissipates, there is a corresponding increase in effective stress, which is crucial for understanding settlement behaviour in geotechnical applications. Building upon this theoretical framework, it is important to note a key assumption inherent in classical 1D consolidation theory: the application of a zero-lateral-strain boundary condition, often referred to as K0 consolidation. This assumption posits that deformation occurs solely in the vertical direction, simplifying the mathematical modelling of soil behaviour under load. While this approach is mathematically convenient and widely adopted for preliminary designs, it has notable limitations. Specifically, it may be mechanically inadequate when analysing the behaviour of highly structured, fibrous peats that experience unconfined embankment loading. In transitioning from theory to practical implications, it becomes evident that overlooking lateral yielding and multi-directional stress redistribution can lead to inaccurate predictions of settlement behavior in more complex soil profiles. As such, engineers must remain cautious when applying 1D consolidation theory to situations involving unconventional soil types, as the unique properties of these materials may necessitate a more nuanced analysis. By recognizing the limitations of classical consolidation theory, practitioners can better address the challenges posed by structured soils, ultimately leading to improved design outcomes and more reliable predictions of settlement over time. \(\:{S}_{p}=\frac{{C}_{c}H}{1+{e}_{o}}\text{log}\frac{{\sigma\:}_{o}+\varDelta\:{\sigma\:}_{z}}{{\sigma\:}_{o}}\) Eq. 1 Which the C c is the compression index, H is height of soil, e o is initial void ratio \(\:{\sigma\:}_{o}\) is the initial vertical effective stress and \(\:\varDelta\:{\sigma\:}_{z}\) final effective vertical stress. The design period considers the total settlement, evaluated over a seven-year post-construction timeframe, in accordance with the design and performance criteria set forth by Jabatan Kerja Raya (JKR). Only cases where the total post-construction settlement did not exceed 400 mm within this seven-year period were considered acceptable. The embankment loading was modeled as a uniform vertical stress increment, and stable groundwater conditions were assumed for analytical consistency. 2.3 Numerical Modelling Using PLAXIS Software To critically evaluate the mechanical limitations of the one-dimensional (1D) theoretical framework, equivalent two-dimensional (2D) finite element analyses (FEA) were executed using PLAXIS software. This advanced numerical approach is essential to capture the complex mechanisms omitted by conventional 1D formulations, specifically multi-directional stress redistribution, non-uniform strain development, and lateral yielding (boundary effects). Within this framework, the Soft Soil Model (SSM) was utilized to represent the underlying peat strata. The SSM is highly advantageous for modelling highly compressible organic soils, as it accurately simulates stress-dependent stiffness, strain localization, and logarithmic compression behaviour under embankment loading as Fig. 1 . To ensure high accuracy in calculating stress concentrations and pore pressure dissipation beneath the embankment footprint, the geometric model was discretized using 15-node triangular elements. To accurately replicate field conditions, the numerical simulation was executed through a rigorous three-stage construction sequence begins with the initial phase. Subsequently, the construction phase simulated the immediate activation of the embankment volume. During this stage, an undrained behavioral framework was temporarily assumed to accurately capture the rapid spike in excess pore pressure resulting from the instantaneous placement of the fill material. The final phase comprised a fully coupled flow-deformation (consolidation) analysis extended over the mandated 7-year design life, facilitating the progressive dissipation of excess pore pressures and the corresponding structural volume reduction. Upon completion of the simulation sequence, the final nodal displacements directly beneath the embankment crest were extracted for comparative evaluation against the one-dimensional analytical predictions as shown in Fig. 2 . 2.4 Isolation of Primary Consolidation Although tropical peat is inherently susceptible to significant long-term secondary compression (creep), the scope of this study is intentionally restricted to evaluating primary consolidation settlement within a specified 7-year design period. This temporal boundary is established in accordance with Jabatan Kerja Raya (JKR) guidelines, which dictate the 7-year timeframe as a critical benchmark for assessing the early-stage serviceability and performance of road embankments. Within this initial period, primary consolidation constitutes the governing mechanical response to external loading. The utilization of the Soft Soil Model (SSM) in PLAXIS provides a robust framework to capture the complex, multi-directional stress-strain behaviors and pore pressure dissipation dynamics unique to this phase. Consequently, while secondary effects are acknowledged as integral to the holistic long-term settlement of peat, the methodology and results presented herein explicitly isolate primary deformation. This focused approach enables a rigorous, mechanically transparent comparison between traditional one-dimensional consolidation theory and advanced two-dimensional numerical predictions, establishing a foundational baseline prior to the onset of complex, viscoplastic creep mechanisms. 2.5 Parametric Sensitivity Analysis and Model Comparison Following the establishment of both the analytical baseline and the numerical model, a comprehensive parametric sensitivity analysis was executed. Key geotechnical variables specifically the compression index (c c ), initial void ratio (e o ), unit weight, and groundwater elevations were systematically varied to map distinct settlement trajectories under applied embankment loading. The primary objective of this phase was to rigorously quantify the predictive divergence between the one-dimensional (1D) theoretical framework and the two-dimensional finite element analysis (2D FEA). The percentage error between the analytically derived and numerically computed settlement magnitudes served as the core quantitative metric of agreement. This systematic evaluation provided critical insights into the specific conditions under which conventional 1D assumptions remain valid, versus scenarios where they significantly deviate from the more advanced, multi-directional spatial kinematics captured by the FEA. Ultimately, this rigorous comparative analysis facilitated the establishment of explicit geotechnical thresholds across distinct peat classifications (fibric, hemic, and sapric). By identifying the exact parametric limits at which simplified 1D theories break down, this study provides robust, evidence-based guidelines that dictate when advanced numerical modeling becomes strictly mandatory. Consequently, these thresholds equip practitioners with the necessary framework to safely back calculate maximum embankment heights, H emb and ensure long-term structural serviceability without resorting to over-conservative, empirical guesswork. 3 Results and Discussion 3.1 Overview of Settlement Trends A comprehensive parametric sensitivity analysis was conducted to evaluate the settlement behavior of tropical peat under road embankment loading. This phase involved a rigorous comparison between one-dimensional (1D) analytical solutions governed by Terzaghi’s Consolidation Theory and two-dimensional (2D) Finite Element Analysis (FEA) utilizing the Soft Soil Model (SSM) within the PLAXIS environment. The comparative results demonstrate a high degree of convergence between the theoretical and numerical frameworks. Regression analysis yielded a coefficient of determination (R 2 ) of from 0.9825 up to 0.9987, signifying a robust correlation and verifying that the SSM constitutive parameters accurately capture the primary consolidation characteristics of the peat. As illustrated in Fig. 3 , the scatter plots for each governing parameter show that the numerical outputs align closely with the 1:1 parity line, confirming the reliability and predictive accuracy of the PLAXIS 2D model in simulating peat settlement behaviour. 3.2 Influence of Compression Index (c c ) and Initial Void Ratio (e o ) The parametric investigation identified the c c and e o as the primary governing variables for settlement magnitude and model divergence. As illustrated in Fig. 1 , a linear-logarithmic escalation in settlement was observed with increasing c c , particularly in fibric regimes where c c > 5.0 resulted in total settlements exceeding 1,500 mm. However, the relationship between e o and numerical accuracy exhibited a complex, non-linear mechanical response. While the 1D analytical framework (Eq. 1) assumes a static, inverse relationship between e o and vertical strain, the PLAXIS Finite Element Analysis (FEA) revealed significant predictive discrepancies. As shown in Fig. 4 , these discrepancies peaked at a 10% error margin in fibric peat scenarios characterized by high c c and e o . This divergence is fundamentally rooted in the kinematic constraints inherent in Terzaghi’s consolidation theory compared to the multi-axial stress-strain response of the Soft Soil Model (SSM). Terzaghi’s 1D model strictly imposes a zero-lateral strain condition. In contrast, the FEA displacement contours in Fig. 5 and Fig. 6 , demonstrate significant lateral yielding and structural rearrangement. In highly fibrous and porous peat matrices, embankment loading induces substantial lateral "bulging" and multidirectional stress redistribution before vertical consolidation is fully mobilized. Consequently, while manual calculations force all volumetric strain into the vertical plane leading to potential systematic error the SSM captures the lateral yielding characteristic of tropical peat. Interestingly, at higher initial void ratios where structural collapse dominates, the error margins converged to within 3–9%. This suggests that once the fibrous matrix undergoes initial structural failure, the peat begins to behave closer to a classical continuum, effectively narrowing the gap between 1D theoretical assumptions and 2D numerical simulations. 3.4 Influence of Peat Depth (D p ) The thickness of the compressible peat layer D p was found to be a dominant factor in governing settlement magnitude and the relative accuracy of the 1D analytical framework. As demonstrated in Fig. 7 , settlement magnitudes escalated proportionally with layer thickness across all peat types. While the analytical approach yielded consistent results for Hemic and Sapric peats with error margins maintained between 2–9% significant predictive divergence was observed in deeper Fibric deposits. This behavior elucidates a fundamental limitation of 1D manual formulations regarding vertical stress distribution assumptions. Manual calculations typically utilize simplified stress increment methods as in the 2:1 distribution or Boussinesq approximations, applied uniformly across discretized soil sub-layers. Conversely, the Finite Element Analysis (FEA) framework computes a continuous, non-linear stress redistribution. As illustrated by the displacement and stress contours in Fig. 8 , the "stress bulb" generated by the embankment diffuses non-linearly through the D p continuum. The Soft Soil Model (SSM) within PLAXIS accounts for strain localization and the progressive stiffening (modulus evolution) of the upper peat layers as they undergo initial compression. This compression leads to a dynamic redistribution of stress increments to the underlying strata. Because the analytical method fails to dynamically update the soil's stiffness modulus (E s ) as a function of the instantaneous state of stress and strain, it tends to incur cumulative errors in deeper deposits. The convergence of Hemic and Sapric results suggests that their higher initial density provides a more stable modulus, whereas the highly porous and "compressible" nature of thick Fibric peat layers necessitates the multi-axial, non-linear stress-strain integration provided by FEA to achieve reliable settlement predictions. 3.5 Influence of Groundwater Level Fluctuations in the groundwater table were found to significantly modulate the effective stress regime within the peat continuum. As illustrated in Fig. 9 , lowering the GWL resulted in a proportional increase in total settlement across all types (Fibric, Hemic, and Sapric), primarily due to the loss of buoyant support and the subsequent increase in the submerged unit weight of the upper peat layers. The comparative analysis revealed that predictive discrepancies between the analytical and numerical methodologies reached a maximum of 12% when the GWL was coincided with the ground surface (GWL = 0.0 m). This peak divergence is attributed to the contrasting treatment of pore water pressure and saturation at the soil-atmosphere boundary. The 1D analytical framework adopts a simplified binary approach, utilizing either fully saturated or dry unit weights. In contrast, the FEA models in PLAXIS incorporate a continuous pore-pressure profile and account for the phreatic surface's influence on stress redistribution. As shown in the displacement contours (Fig. 10 ), the numerical simulation captures the nuanced effective stress changes near the phreatic line, whereas the manual calculations tend to overestimate settlement under shallow GWL conditions by oversimplifying the buoyancy effects. However, as the GWL depth increases more than 1.0 m and hydrostatic conditions stabilize within the compressible zone, the percentage error diminishes significantly to approximately 0–4%. This convergence validates the precision of 1D formulations under purely hydrostatic, fully saturated conditions at depth, where the complexities of the soil-water interface are less pronounced. 3.6 Influence of Embankment Height The elevation of embankment height H emb induced a profound escalation in total settlement, with magnitudes typically increasing by 45–60% due to the substantial vertical stress increments as shown in the Fig. 11 . Remarkably, despite the extreme deformations associated with higher embankments, the predictive discrepancy between the 1D analytical and 2D numerical models remained stable within a narrow 4–9% margin. This stability, while initially counterintuitive given the magnitude of settlement, can be explained through the mechanics of large-scale consolidation and strain-hardening. Under significant embankment loads, the peat matrix undergoes rapid primary compression, leading to a drastic reduction in the void ratio and a transition into a significantly stiffer mechanical state. A critical differentiator in this analysis is the treatment of geometric changes. While the 1D analytical formulation calculates settlement based on the initial thickness, D p the PLAXIS Finite Element framework utilizes an Updated Mesh (Large Strain) formulation. This accounts for the continuous geometric thinning of the peat layer throughout the simulation period. The convergence of results under massive loading suggests that once the overburden pressure reaches a critical threshold, the peat is compressed so thoroughly and uniformly beneath the embankment centerline that multi-directional lateral yielding effects become secondary to the dominant vertical volumetric reduction as provided visual in Fig. 12 . Consequently, the fundamental 1D consolidation assumption remains robust even at extreme settlement scales, as the material’s behavior is increasingly governed by pure vertical densification rather than structural fiber rearrangement. 3.7 Influence of Embankment Unit Weight The influence of embankment unit weight on settlement magnitude and predictive variance was systematically evaluated. As illustrated in Fig. 13 , an escalation in γ emb from 15 kN/m³ to 19 kN/m³ yielded a consistent, proportional increase in total settlement across all peat classifications, directly corresponding to the intensified vertical stress increment. A significant observation in the comparative analysis is the gradual narrowing of the error margin between the analytical and numerical methodologies. Discrepancies diminished from approximately 8% at lower loading intensities to 5% at higher unit weights. This trend is fundamentally linked to the structural evolution of the peat matrix under increasing overburden pressure. Initially, at lower unit weights, the 1D analytical model struggle to account for the complex, multi-axial stiffness of the highly structured fibrous network. However, higher loading intensities effectively overwhelm the initial structural integrity and macro-porosity of the peat, inducing a state of structural collapse. As the peat transitions from a highly porous, fibrous matrix into a denser, compressed state, its mechanical behavior aligns more closely with the continuum mechanics assumptions inherent in Terzaghi’s 1D consolidation theory. The displacement contours in Fig. 14 , further support this, showing that at higher unit weights, the volumetric strain becomes more vertically dominated as the lateral yielding capacity of the compressed matrix reaches a threshold. Consequently, the convergence of results at higher γ emb values validates the applicability of simplified analytical models once the peat has transitioned into a post-collapse, quasi-continuum state. In conclusion, the study found that classical 1D analytical methods have significant predictive limitations for highly fibrous, fibric peats with high initial void ratios and compression indices, leading to discrepancies of up to 21% due to the inability to account for lateral yielding and multi-directional stress redistribution. However, the models converge under conditions of high stress and decomposition such as in hemic and sapric peats or under massive loads, where the peat becomes strain-hardened and pure vertical consolidation dominates, reducing errors to 3% to 9%. The accuracy of manual calculations is also highly sensitive to the phreatic surface, with shallow groundwater causing higher errors (up to 12%) due to complex matric suction ignored by 1D models becoming strain-hardened and pure vertical consolidation dominates, reducing errors to 3% to 9%. The accuracy of manual calculations is also highly sensitive to the phreatic surface, with shallow groundwater causing higher errors (up to 12%) due to complex matric suction ignored by 1D models. Understanding these parametric patterns is crucial for engineers to accurately back-calculate safe maximum embankment heights, particularly for fibric peats where the extreme void ratio triggers significant lateral mechanisms 3.8 Mechanical Interpretation of Model Divergence The fundamental divergence between the analytical and numerical settlement predictions stems directly from their foundational kinematic boundary assumptions. Classical one-dimensional (1D) consolidation theory operates under a strict zero lateral strain condition. Under this framework, all volumetric strain is forced exclusively into the vertical plane, and the stress distribution is idealized as uniform across the soil column. While mathematically convenient for conventional clays, this rigid confinement assumption is mechanically inadequate for highly structured, highly porous media such as tropical peat. Conversely, two-dimensional finite element analysis (2D FEA) utilizing the Soft Soil Model (SSM) captures the complex, multi-directional deformation mechanisms inherent to these highly compressible deposits. Under embankment loading, the unconfined fibrous matrices of peat undergo significant lateral yielding often manifesting as outward bulging rather than pure vertical compression. The FEA accurately simulates this multi-directional stress redistribution, illustrating that stress propagates laterally outward from the embankment footprint, fundamentally altering the deformation pattern. Furthermore, the SSM framework intrinsically accounts for the macro-pore structural collapse and subsequent fiber rearrangement that dominates the early compression stages of fibric peats. Because the classical 1D model forcibly confines all initial volumetric strain to the vertical axis ignoring lateral expansion entirely it systematically misrepresents the true spatial kinematics of the soil. This inability to account for lateral yielding is the primary driver of the predictive gap between the models, highlighting precisely why advanced 2D numerical formulations are required to capture the true settlement trajectory of highly fibrous peats. 3.9 Role of Primary Consolidation in Peat Behavior The decision to isolate primary consolidation in this study is a deliberate methodological strategy designed to establish a fundamental mechanical baseline for tropical peat behavior under embankment loading. While highly organic soils are universally recognized for their extensive, long-term secondary compression (creep), superimposing these time-dependent, viscoplastic effects often obscures the immediate structural sensitivities of the soil matrix. By strictly dissecting the primary settlement phase governed mechanistically by the expulsion of pore water from void spaces and the subsequent dissipation of excess pore pressure this study accurately maps how fundamental geotechnical parameters directly dictate initial volume change. Evaluating this primary settlement phase over a standard seven-year post-construction period directly aligns with critical engineering design and performance requirements, which prioritize capturing the bulk of initial deformation to ensure early-stage serviceability. Quantifying the predictive gap between one-dimensional theoretical assumptions and two-dimensional numerical models during this specific window provides a vital prerequisite for geotechnical engineers. It establishes the foundational, parameter-driven deformation mechanisms that must be accurately resolved before more complex, long-term rheological creep models can be reliably superimposed or evaluated. 3.10 Engineering Implications for Embankment Design The comparative outcomes of this study provide critical, practice-oriented insights for the safe and efficient design of infrastructure over tropical peatland. Given the extreme compressibility, high structural instability, and severe risk of bearing capacity failure inherent to these highly organic deposits, precise settlement prediction is paramount. By systematically mapping how fundamental variables specifically the compression index (c c ), initial void ratio, e o groundwater elevations, and peat depth dictate settlement trajectories, this research equips geotechnical practitioners with a clear understanding of parameter-driven deformation mechanisms. Accurately assessing these factors is essential to preventing catastrophic structural failures, averting the exceedance of strict serviceability limits, and ultimately reducing prohibitive post-construction maintenance and repair costs. Most importantly, this parametric mapping establishes explicit geotechnical thresholds that directly inform model selection and optimization of safe embankment heights. The findings demonstrate that for decomposed hemic and sapric peats, the predictive deviation between one-dimensional theoretical assumptions and advanced numerical models remains marginal. Consequently, traditional 1D manual calculations remain a reliable, efficient tool for preliminary height estimations in these soils. Conversely, the data reveals that for fibric peats, the extreme initial void ratio consistently triggers complex lateral yielding mechanisms that significantly widen the predictive gap. Under these specific parametric conditions, the study categorically establishes that relying on 1D theory is unsafe, making advanced two-dimensional finite element analysis (FEA) strictly mandatory. Acknowledging and applying these parameter-specific deviations is a critical prerequisite for engineering design. By utilizing these established thresholds, practitioners can confidently back-calculate the absolute safe maximum embankment height, H emb tailored to the specific peat classification, ensuring both immediate stability and long-term structural serviceability. 4 Conclusions This study presented a rigorous multidisciplinary parametric investigation to evaluate the predictive boundaries of classical 1D analytical settlement formulations against advanced 2D Finite Element Analysis (PLAXIS Soft Soil Model) for road embankments constructed over tropical peat. By systematically varying soil classifications, compressibility parameters, and embankment geometries, this research delineates the precise geotechnical thresholds where traditional theories diverge from numerical realities. The principal conclusions drawn from this study indicate that classical 1D analytical methods exhibit significant predictive limitations when applied to highly fibrous, fibric peats characterized by high initial void ratios and high compression indices. In these scenarios, discrepancies between the analytical and numerical models reached up to 21%. This divergence is fundamentally driven by the 1D assumption of zero lateral strain, which fails to account for the lateral yielding, multi-directional stress redistribution, and macro-pore structural collapse captured by the finite element Soft Soil Model. However, convergence is observed under conditions of high stress and decomposition. As the structural integrity of the peat matrix transitions to a more decomposed state, such as in hemic and sapric peats, or when subjected to massive vertical stress increments from high embankment fill or unit weight, the predictive error notably diminishes to a range of 3% to 9%. Under these extreme loading conditions, massive volumetric reduction forces the peat into a strain-hardened continuum where pure vertical consolidation dominates, temporarily validating the classical Terzaghi assumptions. Furthermore, the accuracy of manual calculations is highly sensitive to the phreatic surface, highlighting the significant influence of groundwater and effective stress. Shallow groundwater conditions induced higher prediction errors of up to 12% due to the complex capillary and matric suction dynamics at the soil-atmosphere interface, which are ignored by simple binary unit-weight assumptions but actively computed in PLAXIS. Conversely, deep groundwater conditions yielded highly consistent results, with an error margin of only 0% to 4%. By understanding these parametric patterns, engineers can see exactly how soil parameters dictate settlement behavior. Because the deviation between theoretical and numerical models is generally marginal for hemic/sapric peats, manual calculations remain a reliable tool for initial height estimations. However, the parametric patterns reveal that for fibric peats, the extreme void ratio triggers lateral mechanisms that widen the predictive gap. Acknowledging this parameter-specific deviation is the critical first step for engineers to accurately back-calculate the safe maximum embankment height (H emb ) without risking post-construction failure. Declarations Competing interests The author(s) declare no conflict of interest. Ethics Approval and Consent to Participate Not applicable. Funding No funding was received for this work. Author Contribution N.H.M.N. conceived and designed the research framework, parametric study and performed the analytical calculations, executed the 2D finite element simulations in PLAXIS, and wrote the original manuscript draft. M.K.A.T. and S.N.H.A provided supervision, critical guidance on tropical peat mechanics, and acquired the necessary research funding through the TIER1 and GPPS grants. M.A.A.Z. assisted with the final writing draft. All authors have reviewed and approved the final version of the manuscript. Acknowledgements This research is supported by Universiti Tun Hussein Onn Malaysia (UTHM) through Geran TIER1 (Q859) and Geran Penyelidikan Pascasiswazah GPPS (J036) and GPPS (Q791). Special gratitude to the Research Management Centre (RMC), Faculty of Civil Engineering and Built Environment (FKAAB) and Research Centre for Soft Soil (RECESS) of UTHM for the guidance, encouragement, and valuable support. 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Malaysian J Civil Eng 19(2). https://doi.org/10.11113/mjce.v19.15751 Gui Y, Liu S, Qin X, Wang J (2020) A Case Study of Combined Drainage Consolidation-Preloading Methods for a Highway Subgrade on Peat Soils. Adv Civil Eng 2020(1):8816619. https://doi.org/10.1155/2020/8816619 Himawan A, Sahadewa A, Irsyam M, Mikhail R, Suhendra I, Rifai M, Beckhaus K, Widodo Y, Moormann C, Schweiger HF, Hakim AM, Nawir H, Aldiamar F (2024) Full-scale trial embankment and numerical analysis of mortar column inclusion and high-strength geotextile-reinforced load transfer platform on peat. Front Built Environ 10:1379851. https://doi.org/10.3389/fbuil.2024.1379851 Huat BBK, Asadi A, Kazemian S (2009) Experimental Investigation on Geomechanical Properties of Tropical Organic Soils and Peat Ivakhnova GY, Nevzorov AL (2020) The acceleration of the peat secondary consolidation due to the sorption of bound water with disperse clay. IOP Conference Series: Materials Science and Engineering , 945 (1), 012051. https://doi.org/10.1088/1757-899X/945/1/012051 Jia M, Xu J, Gao C, Mu M, E G (2022) Long-Term Cross-Slope Variation in Highways Built on Soft Soil under Coupling Action of Traffic Load and Consolidation. Sustainability 15(1):33. https://doi.org/10.3390/su15010033 Johari NN, Bakar I, Razali SNM, Wahab N (2016) Fiber Effects on Compressibility of Peat. IOP Conference Series: Materials Science and Engineering , 136 , 012036. https://doi.org/10.1088/1757-899X/136/1/012036 Juha F, Leena K-T, Pyry P (2018) Mass Stabilization as a Ground Improvement Method for Soft Peaty. In B. Topcuoğlu & M. Turan (Eds), Peat . InTech. https://doi.org/10.5772/intechopen.74144 Kamaruidzaman NS, Abu Talib MK, Alias NA, Adnan Z, Madun A, Faculty of Civil and Environmental Engineering,Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, MALAYSIA, Zainal Abidin H, Faculty of Civil and Environmental Engineering,Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, MALAYSIA, Md Dan MF (2019) & Faculty of Civil and Environmental Engineering,Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, MALAYSIA. Peat Stabilization by Using Sugarcane Bagasse Ash (SCBA) as a Partial Cement Replacement Materials. International Journal of Integrated Engineering , 11 (6). https://doi.org/10.30880/ijie.2019.11.06.022 Khing VTC (2016) PEAT AND ORGANIC SOILS CHALLENGES IN ROAD CONSTRUCTION IN SARAWAK: JKR SARAWAK EXPERIENCE Lechowicz Z, Sulewska MJ (2022) Assessment of the Undrained Shear Strength and Settlement of Organic Soils under Embankment Loading Using Artificial Neural Networks. Materials 16(1):125. https://doi.org/10.3390/ma16010125 Mahyan NR, Sa’don M, Truna N, L., John JJ (2023) Correlation of Different Peat Soil Index Properties. Int J Integr Eng 15(6). https://doi.org/10.30880/ijie.2023.15.06.003 Mendoza C, Caicedo B, Duque J (2022) Technical report on the compression, structure, and creep behaviors of lacustrine soil deposits in Bogotá, Colombia. Soils and Foundations , 62 (5), 101215. https://doi.org/10.1016/j.sandf.2022.101215 Meyer Z, Olszewska M (2021) Methods Development for the Constrained Elastic Modulus Investigation of Organic Material in Natural Soil Conditions. Materials 14(22):6842. https://doi.org/10.3390/ma14226842 Mohamad HM, MODULUS OF PEAT SOIL UNDER CYCLIC LOADING (2021) Int J GEOMATE 21(84). https://doi.org/10.21660/2021.84.j2164 . YOUNG’S Murdiyarso D, Lilleskov E, Kolka R (2019) Tropical peatlands under siege: The need for evidence-based policies and strategies. Mitig Adapt Strat Glob Change 24(4):493–505. https://doi.org/10.1007/s11027-019-9844-1 Muroby V, Anwar Makarim C (2020) Design alternative on peat soil. IOP Conference Series: Materials Science and Engineering , 1007 (1), 012178. https://doi.org/10.1088/1757-899X/1007/1/012178 O’Kelly BC, Pichan SP (2013) Effects of decomposition on the compressibility of fibrous peat—A review. Geomech Geoeng 8(4):286–296. https://doi.org/10.1080/17486025.2013.804210 Pakir F, Hasan NAN, Ismail NH, Talib MKA, Madun A, Dan MFM, Yunus NZM, Hayati K (2026) A Systematic Literature Review on Basic Properties of Peat Soils in Malaysia. J Adv Res Appl Sci Eng Technol 63(1):44–53. https://doi.org/10.37934/araset.63.1.4453 Paul A, Hussain M (2020) An experiential investigation on the compressibility behavior of cement-treated Indian peat. Bull Eng Geol Environ 79(3):1471–1485. https://doi.org/10.1007/s10064-019-01623-x Prihatiningsih A, Khohara JW (2023) Road settlement analysis on improved peat soil in Pekanbaru. E3S Web of Conferences , 429 , 04016. https://doi.org/10.1051/e3sconf/202342904016 Rasheed RM, Moghal AAB (2022) Critical appraisal of the behavioral geo-mechanisms of peats/organic soils. Arab J Geosci 15(12):1123. https://doi.org/10.1007/s12517-022-10396-9 Sari UC, Wardani SPR, Muntohar AS, Partono W, Sadono KW (2023) Consolidation settlement prediction and monitoring of toll road embankment at STA 23 + 650 Semarang–Demak Toll Road section. E3S Web of Conferences , 429 , 04026. https://doi.org/10.1051/e3sconf/202342904026 Szczepan Olek B (2019) Experimental evidence about misconception of Terzaghi’s 1-D consolidation theory in terms of degree of consolidation. E3S Web of Conferences , 106 , 01013. https://doi.org/10.1051/e3sconf/201910601013 Tashiro M, Nguyen SH, Inagaki M, Yamada S, Noda T (2015) Simulation of large-scale deformation of ultra-soft peaty ground under test embankment loading and investigation of effective countermeasures against residual settlement and failure. Soils Found 55(2):343–358. https://doi.org/10.1016/j.sandf.2015.02.010 Trinh Dinh T (2024) A study on settlements of road embankments on soft ground using vertical drains. Transp Commun Sci J 75(4):1477–1488. https://doi.org/10.47869/tcsj.75.4.1 Wahab A, Hasan M, Pahang UM, Kusin M, Malaysia FUP, Embong Z, Malaysia UTHO, Zaman U, University QN, Babar ZU, Malaysia Pahang U, Imran MS, Universiti Malaysia Pahang (2022) Physical Properties of Undisturbed Tropical Peat Soil at Pekan District, Pahang, West Malaysia. Int J Integr Eng 14(4). https://doi.org/10.30880/ijie.2022.14.04.031 Yamaguchi H, Ohira Y, Kogure K (1985) Volume Change Characteristics of Undisturbed Fibrous Peat. Soils Found 25(2):119–134. https://doi.org/10.3208/sandf1972.25.2_119 Zainorabidin A, Basri K, Ang KA, Instruments Sdn GDS. Bhd., Mohamad HM, Abu Talib MK, Yusof M, Pakir Z, F., Salikin A (2024) Establishment of Dynamic Properties for Malaysian Peat Soil Using Multichannel Analysis of Surface Waves. International Journal of Integrated Engineering , 16 (4). https://doi.org/10.30880/ijie.2024.16.04.019 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 10 May, 2026 Reviewers agreed at journal 30 Apr, 2026 Reviewers agreed at journal 28 Apr, 2026 Reviewers agreed at journal 20 Apr, 2026 Reviewers invited by journal 18 Apr, 2026 Editor assigned by journal 18 Apr, 2026 Submission checks completed at journal 18 Apr, 2026 First submitted to journal 16 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9438122","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":627561647,"identity":"800aeca4-9073-4172-b07e-d72804e1dd1e","order_by":0,"name":"Nathrah Hanim Muhamad Nazri","email":"","orcid":"","institution":"Tun Hussein Onn University of Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Nathrah","middleName":"Hanim Muhamad","lastName":"Nazri","suffix":""},{"id":627561649,"identity":"764f9fd3-4254-4b0b-a9f2-459167251cd8","order_by":1,"name":"Mohd Khaidir Abu 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peat\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/8d35d1e19a72ace8562b5b75.png"},{"id":108006397,"identity":"4fe1030b-34b1-4587-80aa-0483782955fa","added_by":"auto","created_at":"2026-04-28 12:55:22","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":111796,"visible":true,"origin":"","legend":"\u003cp\u003eDeformation figure of depth of peat a) 1 b) 3 c) 5\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/d141e0a7e36c2c00ec00775a.png"},{"id":108006856,"identity":"36dec3aa-c228-45e3-9eb8-6b126748021a","added_by":"auto","created_at":"2026-04-28 12:57:41","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":120752,"visible":true,"origin":"","legend":"\u003cp\u003eGraph comparison between manual calculations and PLAXIS of groundwater level\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/115b6aaa34eac8fdc9216ec0.png"},{"id":108007518,"identity":"7f8a23c1-4f2b-4e2f-b5fc-d870ba0ca804","added_by":"auto","created_at":"2026-04-28 13:00:19","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":133714,"visible":true,"origin":"","legend":"\u003cp\u003eDeformation figure of groundwater level a) 0.0 b) 0.5 c) 1.0\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/8acd72e5f586a3302482b8ab.png"},{"id":107939008,"identity":"a616a04c-e9d3-433f-bd12-685f33efd747","added_by":"auto","created_at":"2026-04-27 19:07:09","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":142464,"visible":true,"origin":"","legend":"\u003cp\u003eGraph comparison between manual calculations and PLAXIS of height of embankment\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/8a98091583f24e00cdb54271.png"},{"id":108006993,"identity":"e1e566ab-770e-4bd3-beb0-6dcb1e2fb4b6","added_by":"auto","created_at":"2026-04-28 12:58:08","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":139557,"visible":true,"origin":"","legend":"\u003cp\u003eDeformation figure of height of embankment a) 2 b) 4 c) 6\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/1ac3ba19349cfbab1db1f5e5.png"},{"id":108180977,"identity":"0b90e96f-bcfd-458b-84f1-71d4ee90fd9a","added_by":"auto","created_at":"2026-04-30 08:55:53","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":115202,"visible":true,"origin":"","legend":"\u003cp\u003eGraph comparison between manual calculations and PLAXIS of unit weight of embankment\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/6a5f5b65f540ffc24bc15643.png"},{"id":108006145,"identity":"d0bf0463-2fd1-4748-a227-eae5b15a6ce4","added_by":"auto","created_at":"2026-04-28 12:54:00","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":186263,"visible":true,"origin":"","legend":"\u003cp\u003eDeformation figure of unit weight of embankment a) 15 b) 17 c) 19\u003c/p\u003e","description":"","filename":"14.png","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/32abddef456ece0ac90b048e.png"},{"id":108184204,"identity":"66a2cfef-d496-4f43-9bbd-72d41550d49c","added_by":"auto","created_at":"2026-04-30 09:03:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2232108,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9438122/v1/8ec3b738-3611-4e09-b691-8bfe7b3a94b0.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eParametric Sensitivity of Settlement Patterns in Tropical Peat: A Comparative Analysis of 1d Theoretical and 2d Numerical Embankment Models\u003c/p\u003e","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eTropical peat, commonly found in swampy and wetland areas, poses significant challenges in civil engineering due to its unique and problematic geotechnical properties \u003cb\u003e(\u003c/b\u003eHuat et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Mahyan et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). This organic soil, formed from partially decomposed plant material under high water tables, is characterized by extremely high water content (often exceeding 200% and even reaching up to 2200% in Malaysia), high initial void ratios (typically ranging between 5 and 30), high compressibility, and low shear strength (between 5 and 25 kPa)\u003cb\u003e(\u003c/b\u003eJuha et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Mohamad, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; O\u0026rsquo;Kelly \u0026amp; Pichan, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Pakir et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2026\u003c/span\u003e; Wahab et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). These characteristics, along with high porosity and low bulk density, make it very difficult to accurately assess the physical and geotechnical behavior of peat, which can vary significantly based on its location and composition \u003cb\u003e(\u003c/b\u003eMahyan et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Meyer \u0026amp; Olszewska, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Muroby \u0026amp; Anwar Makarim, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; O\u0026rsquo;Kelly \u0026amp; Pichan, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2013\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. In Malaysia, where approximately 2.4 to 3\u0026nbsp;million hectares of peatland exist 1.65\u0026nbsp;million hectares of which are in Sarawak infrastructure development faces serious challenges because of these inherent soil limitations \u003cb\u003e(\u003c/b\u003eKamaruidzaman et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Khing, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Wahab et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eConstructing on peatlands presents significant geotechnical challenges, including bearing capacity failure, excessive instability, and substantial primary and long-term consolidation settlement \u003cb\u003e(\u003c/b\u003eMuroby \u0026amp; Anwar Makarim, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Rasheed \u0026amp; Moghal, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2022\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. These issues often result in severe structural damage, embankment and slope failure, and serviceability problems such as differential settlement and uneven road surfaces\u003cb\u003e(\u003c/b\u003eGofar \u0026amp; Sutejo, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Ivakhnova \u0026amp; Nevzorov, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; O\u0026rsquo;Kelly \u0026amp; Pichan, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2013\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003cp\u003eGiven these risks, accurate prediction of settlement is essential to ensure the structural performance and long-term serviceability of road embankments \u003cb\u003e(\u003c/b\u003eMahyan et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Wahab et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Failure to accurately estimate settlement can lead to costly maintenance, premature infrastructure failure, and violation of design criteria \u003cb\u003e(\u003c/b\u003eAzadnejad et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Trinh Dinh, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2024\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. Therefore, reliable settlement prediction is not only a design requirement but also a critical component of sustainable infrastructure development on peat soils \u003cb\u003e(\u003c/b\u003eMurdiyarso et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Pakir et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2026\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTraditionally, preliminary embankment design over soft soils, including peat, has relied on classical one-dimensional (1D) consolidation theory\u003cb\u003e(\u003c/b\u003eGalaviz-Gonz\u0026aacute;lez et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Jia et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). While widely adopted due to its simplicity, this approach assumes zero lateral strain (K₀ condition) and uniform stress distribution, which oversimplifies the complex behaviour of highly compressible and structured peat soils \u003cb\u003e(\u003c/b\u003eO\u0026rsquo;Kelly \u0026amp; Pichan, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Szczepan Olek, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2019\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003cp\u003eThis assumption becomes mechanically inadequate for fibrous peat deposits subjected to unconfined embankment loading, where significant lateral deformation and multidirectional stress redistribution occur\u003cb\u003e(\u003c/b\u003eMendoza et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Consequently, advanced numerical approaches such as two-dimensional (2D) Finite Element Analysis (FEA), particularly using the Soft Soil Model (SSM) in PLAXIS, have become essential\u003cb\u003e(\u003c/b\u003eHimawan et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Trinh Dinh, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2024\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. These models are capable of capturing strain localisation, stress redistribution, and progressive stiffening behaviour, providing a more realistic representation of peat response under loading \u003cb\u003e(\u003c/b\u003eGalaviz-Gonz\u0026aacute;lez et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Lechowicz \u0026amp; Sulewska, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Tashiro et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite these advancements, a clear quantitative understanding of the divergence between 1D analytical predictions and 2D numerical simulations across varying peat conditions remains limited. Therefore, this study aims to systematically quantify this predictive gap through parametric sensitivity analysis \u003cb\u003e(\u003c/b\u003eO\u0026rsquo;Kelly \u0026amp; Pichan, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Rasheed \u0026amp; Moghal, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2022\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. Key parameters such as compression index (Cₒ) and initial void ratio (e₀) are evaluated to establish geotechnical thresholds that define the applicability limits of 1D theory and the necessity for advanced numerical modelling \u003cb\u003e(\u003c/b\u003eKamaruidzaman et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Ultimately, this framework supports the safe determination of embankment heights and enhances design reliability for peatland infrastructure \u003cb\u003e(\u003c/b\u003ePrihatiningsih \u0026amp; Khohara, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Tashiro et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e"},{"header":"2 Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Data Compilation and Development of the Parametric Database\u003c/h2\u003e \u003cp\u003eThe initial step involved the creation of a comprehensive secondary database detailing the properties of Malaysian tropical peat. This database was essential due to the highly heterogeneous nature of tropical peat deposits, whose mechanical behaviour can vary significantly based on environmental conditions, botanical origin, and fibre composition. The considerable variability in the physical characteristics of tropical peat poses significant challenges for geotechnical engineering. These characteristics can differ greatly across geographical locations due to factors such as temperature, moisture levels, botanical origin, and fibre composition.\u003c/p\u003e \u003cp\u003ePeat is classified into three primary categories based on its degree of decomposition: fibric, hemic, and sapric peat. Fibric peat, being the least decomposed, showcases a well-structured fibre network. Hemic peat displays an intermediate level of decomposition, while sapric peat is highly decomposed and exhibits properties more reminiscent of conventional organic soil. Malaysia is home to extensive peat deposits that represent all three decomposition states. The degree of decomposition has a significant impact on peat compressibility, permeability, and long-term consolidation behaviour, with fibric peat typically exhibiting the highest potential for settlement due to its highly porous structure.\u003c/p\u003e \u003cp\u003eTo ensure that both analytical and numerical models realistically represent field conditions, a secondary database of Malaysian tropical peat properties was developed through the systematic compilation of geotechnical parameters from peer-reviewed journal articles, technical reports, and regional soil investigations.\u003c/p\u003e \u003cp\u003eFrom this compiled dataset, key parameters influencing consolidation behavior were extracted, allowing for the establishment of boundary ranges for a parametric sensitivity analysis. These parameters include initial void ratio, compression index, peat thickness, unit weight, and groundwater level, all of which are well-established as critical variables affecting settlement behavior in peat deposits. The resulting parameter ranges adopted in this study are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGeotechnical parameter ranges for Malaysian tropical peat used in the parametric modelling framework\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSources\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInitial Void Ratio (e\u003csub\u003eo\u003c/sub\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.0\u0026ndash;15.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e(Duraisamy et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Gofar \u0026amp; Sutejo, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Gui et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Himawan et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Huat et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Johari et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Mendoza et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Muroby \u0026amp; Anwar Makarim, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; O\u0026rsquo;Kelly \u0026amp; Pichan, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Paul \u0026amp; Hussain, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Prihatiningsih \u0026amp; Khohara, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Rasheed \u0026amp; Moghal, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Sari et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Yamaguchi et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Zainorabidin et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompression Index (c\u003csub\u003ec\u003c/sub\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.8\u0026ndash;3.15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeat Depth (D\u003csub\u003ep\u003c/sub\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.0 m \u0026ndash; 20.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnit weight peat (γ\u003csub\u003epeat\u003c/sub\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.0\u0026ndash;12.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroundwater Level (GWL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.2 m \u0026ndash; 1.0 m below ground surface.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThese parameter ranges were used to generate both analytical settlement calculations and numerical modelling scenarios, allowing for a consistent comparison between theoretical predictions and finite element results.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Analytical Settlement Prediction Using One-Dimensional Consolidation Theory\u003c/h2\u003e \u003cp\u003eTerzaghi's one-dimensional (1D) consolidation theory serves as a foundational framework for estimating settlement in soil layers subjected to applied loads. This theory, articulated through Eq.\u0026nbsp;1, primarily addresses the compression that occurs due to the expulsion of water from the voids in saturated cohesive soils, leading to observable changes in volume. It emphasizes that primary consolidation is a time-dependent process driven by the dissipation of excess pore water pressure. As this pore pressure dissipates, there is a corresponding increase in effective stress, which is crucial for understanding settlement behaviour in geotechnical applications.\u003c/p\u003e \u003cp\u003eBuilding upon this theoretical framework, it is important to note a key assumption inherent in classical 1D consolidation theory: the application of a zero-lateral-strain boundary condition, often referred to as K0 consolidation. This assumption posits that deformation occurs solely in the vertical direction, simplifying the mathematical modelling of soil behaviour under load. While this approach is mathematically convenient and widely adopted for preliminary designs, it has notable limitations. Specifically, it may be mechanically inadequate when analysing the behaviour of highly structured, fibrous peats that experience unconfined embankment loading.\u003c/p\u003e \u003cp\u003eIn transitioning from theory to practical implications, it becomes evident that overlooking lateral yielding and multi-directional stress redistribution can lead to inaccurate predictions of settlement behavior in more complex soil profiles. As such, engineers must remain cautious when applying 1D consolidation theory to situations involving unconventional soil types, as the unique properties of these materials may necessitate a more nuanced analysis. By recognizing the limitations of classical consolidation theory, practitioners can better address the challenges posed by structured soils, ultimately leading to improved design outcomes and more reliable predictions of settlement over time.\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:{S}_{p}=\\frac{{C}_{c}H}{1+{e}_{o}}\\text{log}\\frac{{\\sigma\\:}_{o}+\\varDelta\\:{\\sigma\\:}_{z}}{{\\sigma\\:}_{o}}\\)\u003c/span\u003e \u003c/span\u003e Eq.\u0026nbsp;1\u003c/p\u003e \u003cp\u003eWhich the C\u003csub\u003ec\u003c/sub\u003e is the compression index, H is height of soil, e\u003csub\u003eo\u003c/sub\u003e is initial void ratio \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\sigma\\:}_{o}\\)\u003c/span\u003e\u003c/span\u003e is the initial vertical effective stress and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:{\\sigma\\:}_{z}\\)\u003c/span\u003e\u003c/span\u003e final effective vertical stress.\u003c/p\u003e \u003cp\u003eThe design period considers the total settlement, evaluated over a seven-year post-construction timeframe, in accordance with the design and performance criteria set forth by Jabatan Kerja Raya (JKR). Only cases where the total post-construction settlement did not exceed 400 mm within this seven-year period were considered acceptable. The embankment loading was modeled as a uniform vertical stress increment, and stable groundwater conditions were assumed for analytical consistency.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Numerical Modelling Using PLAXIS Software\u003c/h2\u003e \u003cp\u003eTo critically evaluate the mechanical limitations of the one-dimensional (1D) theoretical framework, equivalent two-dimensional (2D) finite element analyses (FEA) were executed using PLAXIS software. This advanced numerical approach is essential to capture the complex mechanisms omitted by conventional 1D formulations, specifically multi-directional stress redistribution, non-uniform strain development, and lateral yielding (boundary effects). Within this framework, the Soft Soil Model (SSM) was utilized to represent the underlying peat strata. The SSM is highly advantageous for modelling highly compressible organic soils, as it accurately simulates stress-dependent stiffness, strain localization, and logarithmic compression behaviour under embankment loading as Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo ensure high accuracy in calculating stress concentrations and pore pressure dissipation beneath the embankment footprint, the geometric model was discretized using 15-node triangular elements.\u003c/p\u003e \u003cp\u003eTo accurately replicate field conditions, the numerical simulation was executed through a rigorous three-stage construction sequence begins with the initial phase. Subsequently, the construction phase simulated the immediate activation of the embankment volume. During this stage, an undrained behavioral framework was temporarily assumed to accurately capture the rapid spike in excess pore pressure resulting from the instantaneous placement of the fill material. The final phase comprised a fully coupled flow-deformation (consolidation) analysis extended over the mandated 7-year design life, facilitating the progressive dissipation of excess pore pressures and the corresponding structural volume reduction. Upon completion of the simulation sequence, the final nodal displacements directly beneath the embankment crest were extracted for comparative evaluation against the one-dimensional analytical predictions as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Isolation of Primary Consolidation\u003c/h2\u003e \u003cp\u003eAlthough tropical peat is inherently susceptible to significant long-term secondary compression (creep), the scope of this study is intentionally restricted to evaluating primary consolidation settlement within a specified 7-year design period. This temporal boundary is established in accordance with Jabatan Kerja Raya (JKR) guidelines, which dictate the 7-year timeframe as a critical benchmark for assessing the early-stage serviceability and performance of road embankments.\u003c/p\u003e \u003cp\u003eWithin this initial period, primary consolidation constitutes the governing mechanical response to external loading. The utilization of the Soft Soil Model (SSM) in PLAXIS provides a robust framework to capture the complex, multi-directional stress-strain behaviors and pore pressure dissipation dynamics unique to this phase. Consequently, while secondary effects are acknowledged as integral to the holistic long-term settlement of peat, the methodology and results presented herein explicitly isolate primary deformation. This focused approach enables a rigorous, mechanically transparent comparison between traditional one-dimensional consolidation theory and advanced two-dimensional numerical predictions, establishing a foundational baseline prior to the onset of complex, viscoplastic creep mechanisms.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Parametric Sensitivity Analysis and Model Comparison\u003c/h2\u003e \u003cp\u003eFollowing the establishment of both the analytical baseline and the numerical model, a comprehensive parametric sensitivity analysis was executed. Key geotechnical variables specifically the compression index (c\u003csub\u003ec\u003c/sub\u003e), initial void ratio (e\u003csub\u003eo\u003c/sub\u003e), unit weight, and groundwater elevations were systematically varied to map distinct settlement trajectories under applied embankment loading. The primary objective of this phase was to rigorously quantify the predictive divergence between the one-dimensional (1D) theoretical framework and the two-dimensional finite element analysis (2D FEA).\u003c/p\u003e \u003cp\u003eThe percentage error between the analytically derived and numerically computed settlement magnitudes served as the core quantitative metric of agreement. This systematic evaluation provided critical insights into the specific conditions under which conventional 1D assumptions remain valid, versus scenarios where they significantly deviate from the more advanced, multi-directional spatial kinematics captured by the FEA.\u003c/p\u003e \u003cp\u003eUltimately, this rigorous comparative analysis facilitated the establishment of explicit geotechnical thresholds across distinct peat classifications (fibric, hemic, and sapric). By identifying the exact parametric limits at which simplified 1D theories break down, this study provides robust, evidence-based guidelines that dictate when advanced numerical modeling becomes strictly mandatory. Consequently, these thresholds equip practitioners with the necessary framework to safely back calculate maximum embankment heights, H\u003csub\u003eemb\u003c/sub\u003e and ensure long-term structural serviceability without resorting to over-conservative, empirical guesswork.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results and Discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Overview of Settlement Trends\u003c/h2\u003e\n \u003cp\u003eA comprehensive parametric sensitivity analysis was conducted to evaluate the settlement behavior of tropical peat under road embankment loading. This phase involved a rigorous comparison between one-dimensional (1D) analytical solutions governed by Terzaghi\u0026rsquo;s Consolidation Theory and two-dimensional (2D) Finite Element Analysis (FEA) utilizing the Soft Soil Model (SSM) within the PLAXIS environment. The comparative results demonstrate a high degree of convergence between the theoretical and numerical frameworks. Regression analysis yielded a coefficient of determination (R\u003csup\u003e2\u003c/sup\u003e) of from 0.9825 up to 0.9987, signifying a robust correlation and verifying that the SSM constitutive parameters accurately capture the primary consolidation characteristics of the peat. As illustrated in Fig. \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the scatter plots for each governing parameter show that the numerical outputs align closely with the 1:1 parity line, confirming the reliability and predictive accuracy of the PLAXIS 2D model in simulating peat settlement behaviour.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Influence of Compression Index (c\u003csub\u003ec\u003c/sub\u003e) and Initial Void Ratio (e\u003csub\u003eo\u003c/sub\u003e)\u003c/h2\u003e\n \u003cp\u003eThe parametric investigation identified the c\u003csub\u003ec\u003c/sub\u003e and e\u003csub\u003eo\u003c/sub\u003e as the primary governing variables for settlement magnitude and model divergence. As illustrated in Fig. \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, a linear-logarithmic escalation in settlement was observed with increasing c\u003csub\u003ec\u003c/sub\u003e, particularly in fibric regimes where c\u003csub\u003ec\u003c/sub\u003e \u0026gt; 5.0 resulted in total settlements exceeding 1,500 mm. However, the relationship between e\u003csub\u003eo\u003c/sub\u003e and numerical accuracy exhibited a complex, non-linear mechanical response. While the 1D analytical framework (Eq. 1) assumes a static, inverse relationship between e\u003csub\u003eo\u003c/sub\u003e and vertical strain, the PLAXIS Finite Element Analysis (FEA) revealed significant predictive discrepancies. As shown in Fig. \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, these discrepancies peaked at a 10% error margin in fibric peat scenarios characterized by high c\u003csub\u003ec\u003c/sub\u003e and e\u003csub\u003eo\u003c/sub\u003e. This divergence is fundamentally rooted in the kinematic constraints inherent in Terzaghi\u0026rsquo;s consolidation theory compared to the multi-axial stress-strain response of the Soft Soil Model (SSM). Terzaghi\u0026rsquo;s 1D model strictly imposes a zero-lateral strain condition. In contrast, the FEA displacement contours in Fig. \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Fig. \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, demonstrate significant lateral yielding and structural rearrangement. In highly fibrous and porous peat matrices, embankment loading induces substantial lateral \u0026quot;bulging\u0026quot; and multidirectional stress redistribution before vertical consolidation is fully mobilized. Consequently, while manual calculations force all volumetric strain into the vertical plane leading to potential systematic error the SSM captures the lateral yielding characteristic of tropical peat. Interestingly, at higher initial void ratios where structural collapse dominates, the error margins converged to within 3\u0026ndash;9%. This suggests that once the fibrous matrix undergoes initial structural failure, the peat begins to behave closer to a classical continuum, effectively narrowing the gap between 1D theoretical assumptions and 2D numerical simulations.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 Influence of Peat Depth (D\u003csub\u003ep\u003c/sub\u003e)\u003c/h2\u003e\n \u003cp\u003eThe thickness of the compressible peat layer D\u003csub\u003ep\u003c/sub\u003e was found to be a dominant factor in governing settlement magnitude and the relative accuracy of the 1D analytical framework. As demonstrated in Fig. \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, settlement magnitudes escalated proportionally with layer thickness across all peat types. While the analytical approach yielded consistent results for Hemic and Sapric peats with error margins maintained between 2\u0026ndash;9% significant predictive divergence was observed in deeper Fibric deposits. This behavior elucidates a fundamental limitation of 1D manual formulations regarding vertical stress distribution assumptions. Manual calculations typically utilize simplified stress increment methods as in the 2:1 distribution or Boussinesq approximations, applied uniformly across discretized soil sub-layers. Conversely, the Finite Element Analysis (FEA) framework computes a continuous, non-linear stress redistribution. As illustrated by the displacement and stress contours in Fig. \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, the \u0026quot;stress bulb\u0026quot; generated by the embankment diffuses non-linearly through the D\u003csub\u003ep\u003c/sub\u003e continuum. The Soft Soil Model (SSM) within PLAXIS accounts for strain localization and the progressive stiffening (modulus evolution) of the upper peat layers as they undergo initial compression. This compression leads to a dynamic redistribution of stress increments to the underlying strata. Because the analytical method fails to dynamically update the soil\u0026apos;s stiffness modulus (E\u003csub\u003es\u003c/sub\u003e) as a function of the instantaneous state of stress and strain, it tends to incur cumulative errors in deeper deposits. The convergence of Hemic and Sapric results suggests that their higher initial density provides a more stable modulus, whereas the highly porous and \u0026quot;compressible\u0026quot; nature of thick Fibric peat layers necessitates the multi-axial, non-linear stress-strain integration provided by FEA to achieve reliable settlement predictions.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003e3.5 Influence of Groundwater Level\u003c/h2\u003e\n \u003cp\u003eFluctuations in the groundwater table were found to significantly modulate the effective stress regime within the peat continuum. As illustrated in Fig. \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, lowering the GWL resulted in a proportional increase in total settlement across all types (Fibric, Hemic, and Sapric), primarily due to the loss of buoyant support and the subsequent increase in the submerged unit weight of the upper peat layers. The comparative analysis revealed that predictive discrepancies between the analytical and numerical methodologies reached a maximum of 12% when the GWL was coincided with the ground surface (GWL\u0026thinsp;=\u0026thinsp;0.0 m). This peak divergence is attributed to the contrasting treatment of pore water pressure and saturation at the soil-atmosphere boundary. The 1D analytical framework adopts a simplified binary approach, utilizing either fully saturated or dry unit weights. In contrast, the FEA models in PLAXIS incorporate a continuous pore-pressure profile and account for the phreatic surface\u0026apos;s influence on stress redistribution. As shown in the displacement contours (Fig. \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e), the numerical simulation captures the nuanced effective stress changes near the phreatic line, whereas the manual calculations tend to overestimate settlement under shallow GWL conditions by oversimplifying the buoyancy effects. However, as the GWL depth increases more than 1.0 m and hydrostatic conditions stabilize within the compressible zone, the percentage error diminishes significantly to approximately 0\u0026ndash;4%. This convergence validates the precision of 1D formulations under purely hydrostatic, fully saturated conditions at depth, where the complexities of the soil-water interface are less pronounced.\u003c/p\u003e\n \n \n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003e3.6 Influence of Embankment Height\u003c/h2\u003e\n \u003cp\u003eThe elevation of embankment height H\u003csub\u003eemb\u003c/sub\u003e induced a profound escalation in total settlement, with magnitudes typically increasing by 45\u0026ndash;60% due to the substantial vertical stress increments as shown in the Fig. \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e. Remarkably, despite the extreme deformations associated with higher embankments, the predictive discrepancy between the 1D analytical and 2D numerical models remained stable within a narrow 4\u0026ndash;9% margin. This stability, while initially counterintuitive given the magnitude of settlement, can be explained through the mechanics of large-scale consolidation and strain-hardening. Under significant embankment loads, the peat matrix undergoes rapid primary compression, leading to a drastic reduction in the void ratio and a transition into a significantly stiffer mechanical state. A critical differentiator in this analysis is the treatment of geometric changes. While the 1D analytical formulation calculates settlement based on the initial thickness, D\u003csub\u003ep\u003c/sub\u003e the PLAXIS Finite Element framework utilizes an Updated Mesh (Large Strain) formulation. This accounts for the continuous geometric thinning of the peat layer throughout the simulation period. The convergence of results under massive loading suggests that once the overburden pressure reaches a critical threshold, the peat is compressed so thoroughly and uniformly beneath the embankment centerline that multi-directional lateral yielding effects become secondary to the dominant vertical volumetric reduction as provided visual in Fig. \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e. Consequently, the fundamental 1D consolidation assumption remains robust even at extreme settlement scales, as the material\u0026rsquo;s behavior is increasingly governed by pure vertical densification rather than structural fiber rearrangement.\u003c/p\u003e\n \n \n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003e3.7 Influence of Embankment Unit Weight\u003c/h2\u003e\n \u003cp\u003eThe influence of embankment unit weight on settlement magnitude and predictive variance was systematically evaluated. As illustrated in Fig. \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e, an escalation in \u0026gamma;\u003csub\u003eemb\u003c/sub\u003e from 15 kN/m\u0026sup3; to 19 kN/m\u0026sup3; yielded a consistent, proportional increase in total settlement across all peat classifications, directly corresponding to the intensified vertical stress increment. A significant observation in the comparative analysis is the gradual narrowing of the error margin between the analytical and numerical methodologies. Discrepancies diminished from approximately 8% at lower loading intensities to 5% at higher unit weights. This trend is fundamentally linked to the structural evolution of the peat matrix under increasing overburden pressure. Initially, at lower unit weights, the 1D analytical model struggle to account for the complex, multi-axial stiffness of the highly structured fibrous network. However, higher loading intensities effectively overwhelm the initial structural integrity and macro-porosity of the peat, inducing a state of structural collapse. As the peat transitions from a highly porous, fibrous matrix into a denser, compressed state, its mechanical behavior aligns more closely with the continuum mechanics assumptions inherent in Terzaghi\u0026rsquo;s 1D consolidation theory. The displacement contours in Fig. \u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e, further support this, showing that at higher unit weights, the volumetric strain becomes more vertically dominated as the lateral yielding capacity of the compressed matrix reaches a threshold. Consequently, the convergence of results at higher \u0026gamma;\u003csub\u003eemb\u003c/sub\u003e values validates the applicability of simplified analytical models once the peat has transitioned into a post-collapse, quasi-continuum state.\u003c/p\u003e\n \n \n \u003cp\u003eIn conclusion, the study found that classical 1D analytical methods have significant predictive limitations for highly fibrous, fibric peats with high initial void ratios and compression indices, leading to discrepancies of up to 21% due to the inability to account for lateral yielding and multi-directional stress redistribution. However, the models converge under conditions of high stress and decomposition such as in hemic and sapric peats or under massive loads, where the peat becomes strain-hardened and pure vertical consolidation dominates, reducing errors to 3% to 9%. The accuracy of manual calculations is also highly sensitive to the phreatic surface, with shallow groundwater causing higher errors (up to 12%) due to complex matric suction ignored by 1D models becoming strain-hardened and pure vertical consolidation dominates, reducing errors to 3% to 9%. The accuracy of manual calculations is also highly sensitive to the phreatic surface, with shallow groundwater causing higher errors (up to 12%) due to complex matric suction ignored by 1D models. Understanding these parametric patterns is crucial for engineers to accurately back-calculate safe maximum embankment heights, particularly for fibric peats where the extreme void ratio triggers significant lateral mechanisms\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n \u003ch2\u003e3.8 Mechanical Interpretation of Model Divergence\u003c/h2\u003e\n \u003cp\u003eThe fundamental divergence between the analytical and numerical settlement predictions stems directly from their foundational kinematic boundary assumptions. Classical one-dimensional (1D) consolidation theory operates under a strict zero lateral strain condition. Under this framework, all volumetric strain is forced exclusively into the vertical plane, and the stress distribution is idealized as uniform across the soil column. While mathematically convenient for conventional clays, this rigid confinement assumption is mechanically inadequate for highly structured, highly porous media such as tropical peat. Conversely, two-dimensional finite element analysis (2D FEA) utilizing the Soft Soil Model (SSM) captures the complex, multi-directional deformation mechanisms inherent to these highly compressible deposits. Under embankment loading, the unconfined fibrous matrices of peat undergo significant lateral yielding often manifesting as outward bulging rather than pure vertical compression. The FEA accurately simulates this multi-directional stress redistribution, illustrating that stress propagates laterally outward from the embankment footprint, fundamentally altering the deformation pattern. Furthermore, the SSM framework intrinsically accounts for the macro-pore structural collapse and subsequent fiber rearrangement that dominates the early compression stages of fibric peats. Because the classical 1D model forcibly confines all initial volumetric strain to the vertical axis ignoring lateral expansion entirely it systematically misrepresents the true spatial kinematics of the soil. This inability to account for lateral yielding is the primary driver of the predictive gap between the models, highlighting precisely why advanced 2D numerical formulations are required to capture the true settlement trajectory of highly fibrous peats.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n \u003ch2\u003e3.9 Role of Primary Consolidation in Peat Behavior\u003c/h2\u003e\n \u003cp\u003eThe decision to isolate primary consolidation in this study is a deliberate methodological strategy designed to establish a fundamental mechanical baseline for tropical peat behavior under embankment loading. While highly organic soils are universally recognized for their extensive, long-term secondary compression (creep), superimposing these time-dependent, viscoplastic effects often obscures the immediate structural sensitivities of the soil matrix. By strictly dissecting the primary settlement phase governed mechanistically by the expulsion of pore water from void spaces and the subsequent dissipation of excess pore pressure this study accurately maps how fundamental geotechnical parameters directly dictate initial volume change.\u003c/p\u003e\n \u003cp\u003eEvaluating this primary settlement phase over a standard seven-year post-construction period directly aligns with critical engineering design and performance requirements, which prioritize capturing the bulk of initial deformation to ensure early-stage serviceability. Quantifying the predictive gap between one-dimensional theoretical assumptions and two-dimensional numerical models during this specific window provides a vital prerequisite for geotechnical engineers. It establishes the foundational, parameter-driven deformation mechanisms that must be accurately resolved before more complex, long-term rheological creep models can be reliably superimposed or evaluated.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003e3.10 Engineering Implications for Embankment Design\u003c/h2\u003e\n \u003cp\u003eThe comparative outcomes of this study provide critical, practice-oriented insights for the safe and efficient design of infrastructure over tropical peatland. Given the extreme compressibility, high structural instability, and severe risk of bearing capacity failure inherent to these highly organic deposits, precise settlement prediction is paramount. By systematically mapping how fundamental variables specifically the compression index (c\u003csub\u003ec\u003c/sub\u003e), initial void ratio, e\u003csub\u003eo\u003c/sub\u003e groundwater elevations, and peat depth dictate settlement trajectories, this research equips geotechnical practitioners with a clear understanding of parameter-driven deformation mechanisms. Accurately assessing these factors is essential to preventing catastrophic structural failures, averting the exceedance of strict serviceability limits, and ultimately reducing prohibitive post-construction maintenance and repair costs. Most importantly, this parametric mapping establishes explicit geotechnical thresholds that directly inform model selection and optimization of safe embankment heights. The findings demonstrate that for decomposed hemic and sapric peats, the predictive deviation between one-dimensional theoretical assumptions and advanced numerical models remains marginal. Consequently, traditional 1D manual calculations remain a reliable, efficient tool for preliminary height estimations in these soils. Conversely, the data reveals that for fibric peats, the extreme initial void ratio consistently triggers complex lateral yielding mechanisms that significantly widen the predictive gap. Under these specific parametric conditions, the study categorically establishes that relying on 1D theory is unsafe, making advanced two-dimensional finite element analysis (FEA) strictly mandatory. Acknowledging and applying these parameter-specific deviations is a critical prerequisite for engineering design. By utilizing these established thresholds, practitioners can confidently back-calculate the absolute safe maximum embankment height, H\u003csub\u003eemb\u003c/sub\u003e tailored to the specific peat classification, ensuring both immediate stability and long-term structural serviceability.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4 Conclusions","content":"\u003cp\u003eThis study presented a rigorous multidisciplinary parametric investigation to evaluate the predictive boundaries of classical 1D analytical settlement formulations against advanced 2D Finite Element Analysis (PLAXIS Soft Soil Model) for road embankments constructed over tropical peat. By systematically varying soil classifications, compressibility parameters, and embankment geometries, this research delineates the precise geotechnical thresholds where traditional theories diverge from numerical realities.\u003c/p\u003e \u003cp\u003eThe principal conclusions drawn from this study indicate that classical 1D analytical methods exhibit significant predictive limitations when applied to highly fibrous, fibric peats characterized by high initial void ratios and high compression indices. In these scenarios, discrepancies between the analytical and numerical models reached up to 21%. This divergence is fundamentally driven by the 1D assumption of zero lateral strain, which fails to account for the lateral yielding, multi-directional stress redistribution, and macro-pore structural collapse captured by the finite element Soft Soil Model.\u003c/p\u003e \u003cp\u003eHowever, convergence is observed under conditions of high stress and decomposition. As the structural integrity of the peat matrix transitions to a more decomposed state, such as in hemic and sapric peats, or when subjected to massive vertical stress increments from high embankment fill or unit weight, the predictive error notably diminishes to a range of 3% to 9%. Under these extreme loading conditions, massive volumetric reduction forces the peat into a strain-hardened continuum where pure vertical consolidation dominates, temporarily validating the classical Terzaghi assumptions.\u003c/p\u003e \u003cp\u003eFurthermore, the accuracy of manual calculations is highly sensitive to the phreatic surface, highlighting the significant influence of groundwater and effective stress. Shallow groundwater conditions induced higher prediction errors of up to 12% due to the complex capillary and matric suction dynamics at the soil-atmosphere interface, which are ignored by simple binary unit-weight assumptions but actively computed in PLAXIS. Conversely, deep groundwater conditions yielded highly consistent results, with an error margin of only 0% to 4%.\u003c/p\u003e \u003cp\u003eBy understanding these parametric patterns, engineers can see exactly how soil parameters dictate settlement behavior. Because the deviation between theoretical and numerical models is generally marginal for hemic/sapric peats, manual calculations remain a reliable tool for initial height estimations. However, the parametric patterns reveal that for fibric peats, the extreme void ratio triggers lateral mechanisms that widen the predictive gap. Acknowledging this parameter-specific deviation is the critical first step for engineers to accurately back-calculate the safe maximum embankment height (H\u003csub\u003eemb\u003c/sub\u003e) without risking post-construction failure.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe author(s) declare no conflict of interest.\u003c/p\u003e\n\u003ch2\u003eEthics Approval and Consent to Participate\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eNo funding was received for this work.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eN.H.M.N. conceived and designed the research framework, parametric study and performed the analytical calculations, executed the 2D finite element simulations in PLAXIS, and wrote the original manuscript draft. M.K.A.T. and S.N.H.A provided supervision, critical guidance on tropical peat mechanics, and acquired the necessary research funding through the TIER1 and GPPS grants. M.A.A.Z. assisted with the final writing draft. All authors have reviewed and approved the final version of the manuscript.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eThis research is supported by Universiti Tun Hussein Onn Malaysia (UTHM) through Geran TIER1 (Q859) and Geran Penyelidikan Pascasiswazah GPPS (J036) and GPPS (Q791). Special gratitude to the Research Management Centre (RMC), Faculty of Civil Engineering and Built Environment (FKAAB) and Research Centre for Soft Soil (RECESS) of UTHM for the guidance, encouragement, and valuable support.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAzadnejad S, Hrysiewicz A, Trafford A, O\u0026rsquo;Loughlin F, Holohan EP, Kelly F, Donohue S (2024) InSAR supported by geophysical and geotechnical information constrains two-dimensional motion of a railway embankment constructed on peat. 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Bhd., Mohamad HM, Abu Talib MK, Yusof M, Pakir Z, F., Salikin A (2024) Establishment of Dynamic Properties for Malaysian Peat Soil Using Multichannel Analysis of Surface Waves. \u003cem\u003eInternational Journal of Integrated Engineering\u003c/em\u003e, \u003cem\u003e16\u003c/em\u003e(4). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.30880/ijie.2024.16.04.019\u003c/span\u003e\u003cspan address=\"10.30880/ijie.2024.16.04.019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"multiscale-and-multidisciplinary-modeling-experiments-and-design","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mmed","sideBox":"Learn more about [Multiscale and Multidisciplinary Modeling, Experiments and Design](https://link.springer.com/journal/41939)","snPcode":"41939","submissionUrl":"https://submission.nature.com/new-submission/41939/3","title":"Multiscale and Multidisciplinary Modeling, Experiments and Design","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Tropical peat, Finite element modelling, Settlement prediction, Soft Soil Model, Parametric analysis","lastPublishedDoi":"10.21203/rs.3.rs-9438122/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9438122/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTropical peat deposits present profound challenges for infrastructure due to their extreme compressibility. To eventually determine safe embankment construction heights, it is first necessary to thoroughly understand how specific geotechnical parameters influence primary settlement patterns. This study presents a parametric sensitivity analysis of road embankments over Malaysian tropical peats (fibric, hemic, and sapric). To isolate and understand these behavioral patterns, settlement was evaluated using a theoretical 1D analytical baseline and compared against 2D Finite Element Analysis utilizing the Soft Soil Model (SSM). By systematically varying the compression index, initial void ratio, unit weight, and groundwater levels, the study maps the settlement trajectories. The results demonstrate that for decomposed peats under standard loading, the numerical and analytical patterns align closely, validating traditional 1D consolidation theories. However, significant predictive divergence (up to 21%) is triggered under specific parametric combinations namely, highly fibrous peats with maximum initial void ratios. This gap highlights the exact parametric thresholds where multi-directional stress redistribution and lateral yielding dominate. By mapping these parameter-driven deviations, this study establishes the fundamental behavioral framework required to optimize safe embankment heights in complex peat environments.\u003c/p\u003e","manuscriptTitle":"Parametric Sensitivity of Settlement Patterns in Tropical Peat: A Comparative Analysis of 1d Theoretical and 2d Numerical Embankment Models","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-27 19:07:04","doi":"10.21203/rs.3.rs-9438122/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-10T08:21:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"76184987685259187783575024436609280179","date":"2026-04-30T18:19:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"154320103307834681080607768318664185753","date":"2026-04-28T17:39:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"102356161591633156060041232535477163110","date":"2026-04-21T01:54:15+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-18T15:08:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-18T15:05:42+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-18T11:53:32+00:00","index":"","fulltext":""},{"type":"submitted","content":"Multiscale and Multidisciplinary Modeling, Experiments and Design","date":"2026-04-16T12:16:22+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"multiscale-and-multidisciplinary-modeling-experiments-and-design","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mmed","sideBox":"Learn more about [Multiscale and Multidisciplinary Modeling, Experiments and Design](https://link.springer.com/journal/41939)","snPcode":"41939","submissionUrl":"https://submission.nature.com/new-submission/41939/3","title":"Multiscale and Multidisciplinary Modeling, Experiments and Design","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"45e7de72-6a90-4076-bbcb-a76241fe0054","owner":[],"postedDate":"April 27th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-10T08:21:56+00:00","index":35,"fulltext":""},{"type":"reviewerAgreed","content":"76184987685259187783575024436609280179","date":"2026-04-30T18:19:50+00:00","index":32,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T19:07:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-27 19:07:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9438122","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9438122","identity":"rs-9438122","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}