Implications of Blasting-Induced Vibration on the Stability of Hydroelectric Power Tunnel

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PT. Kerinci Merangin Hidro is actively engaged in the construction of hydropower plants, with a focus on creating two types of tunnels. During blasting activities with a target progress rate of 50 m in a month, high explosives are commonly used between 500 and 600 PCS days. However, this method leads to vibrations that negatively impact tunnel stability, causing the formation of new cracks in walls. Data processing was conducted using Blastware 10.7 instant software, RS2/Phase2 software and the finite element method. The classification of rock masses included the use of the Rock Mass Rating (RMR) and the Q-System. The research results showed that Fair Rock class (III) rocks were identified at the six observation stations based on the classification of rock masses according to RMR 1989. There was a significant decrease in the weight of the rock mass before and after blasting at each station. The safety factor ranged from 1.26 to 6.00. A greater blasting agent weight per delay resulted in increased vibration across the six patterns. The most significant decrease in safety factors occurred only in pattern 6, with the highest tremor recorded at 1.1220 m/s 2 . Comparing patterns 5 and 6 with the same blasting agent weight per delay of 8.8 kg and equal explosive load of 550 kg showed that the highest decrease in safety factor values occurred in pattern 6. This phenomenon can be attributed to the fact that a shorter delay produces greater vibration than a longer delay time. blasting safety factor vibration tunnel hydropower plants Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction An adit tunnel is a horizontal opening used for accessing a headrace in a hydroelectric power tunnel. Various factors contribute to ensuring tunnel stability, with a particular focus on maintaining stability by limiting the maximum total displacement to 0.2 mm/day (Zhenxiang, n.d., Wang, et al., 2023 , Y. Zhang et al., 2022 , Zhang et al., 2023 ). Additionally, a safety factor of 1.5 or higher is maintained for electric hydropower (Brown, 2015 , Hoek and Brown, 2019 , Hu et al., 2023 , Zhang et al., 2020 , Nedevska et al., 2020 ). PT. Kerinci Merangin Hidro is actively engaged in the construction of hydropower plants, with a focus on creating two types of tunnels. The main tunnel, referred to as the headrace, serves as the primary water drainage site, while the auxiliary tunnel (adit) functions as an access point to the main tunnel. Both tunnels are constructed using drilling and blasting methods. The stability of a tunnel is considered to be safe against the effect of detonation when safety factor calculations reveal minimal differences (Jasipto et al., 2020 ). This is crucial because the initiation of vibration during blasting is influenced by several factors, such as the number of fillings, delay number placement, delay interval, and correlation of explosive charges (Huang et al., 2019 , Ittner et al., 2019 , Ma et al., 2020 , Soltani-Mohammadi et al., 2012 , B. Zhang et al., 2022 ). During blasting activities with a target progress rate of 50 m in a month, high explosives are commonly used between 500 and 600 PCS days. However, this method leads to vibrations that negatively impact tunnel stability, causing the formation of new cracks in walls. Direct observations made during the initial STA showed signs of collapse, despite the tunnel having been in a safe condition previously. 2. Area and Geological Observation The Kerinci Merangin Hydro hydropower plant is located on the southwest slope of Bukit Barisan on Sumatra Island. The plant site was approximately 448 km southwest of Jambi Municipality, capital of Jambi Province, with coordinates of 2°14′5.72" − 2°11′26.4" South Latitude and 101°40′18.54" – 101°45′44.94" East Longitude. The 450 MW Kerinci hydropower plant comprises several main components, including a regulating weir, intake dam, headrace tunnel, headrace surge shaft, penstock, and powerhouse. This hydropower plant features four turbines designed for a franchise type and a headrace tunnel length of ± 14 km, as do the other three adits within the project. Adit Tunnel 1 had a length of ± 504 m, Tunnel 2 measured approximately 912 m, and Adit 4 spanned ± 409 m. 3. Geological Structure The project site, located approximately 20 km southwest, was positioned outside the Semangko fault, an active fault system. Despite being outside the fault area, the regional stress distribution in the bedrock was potentially connected to the Sumatran Fault System. However, detailed in situ stress conditions were challenging to determine for technical reasons during this investigation. Geological investigations further showed that the rocks surrounding the powerhouse tunnel were Batusabak and sandstone in the Asai Formation. The average strike and dip values, measured at N45°W/40°SW, provided a representative orientation of the layers at the underground tunnel site. 4. Methodology a. Data To address the study objectives, essential data were the primary input for the analysis process. The required data included various parameters, including the RMR, such as the RQD, discontinuity spacing, conditions, orientation, and groundwater, as well as Q-System indicators, such as the RQD, number of joint pairs (Jn), joint roughness level (Jr), joint alteration (Ja), groundwater flow (Jw), and stress reduction factor (SRF). The additional data included the actual peak particle velocity (PPV), geological structure measurements in the field, tunnel geometry and blasting pattern. Secondary data, including geological data, physical and mechanical properties of rocks, explosive specifications, and regional geologic maps, were also essential for comprehensive analysis. Various instruments were used to collect data, with the Vibration Measuring Device (Blastmate III) playing a crucial role in reading vibrations generated during blasting activities. The geological compass measured the strike/dip direction of structures (joints) on the walls of holes and axial tunnels. GPS was used to plot coordinates at each data collection point (STA), while a geological hammer was used to facilitate rock sampling. Furthermore, a meter was used as a measuring device for determining the distance from the blasting site to the observation location. b. Data Processing Methods 1) Peak Particle Velocity (PPV) The data were processed using Blastware 10.7 instant software, which included the input of information such as longitudinal, vertical, and transverse wave recordings. The other data included the peak particle acceleration, airblast recording, measuring distance, and number of explosives per pit. The program subsequently generated a square root graph based on the values of the k and m coefficients, which was instrumental in determining the vibration PPV at various distances. 2) Rock mass classification (dup: abstract ?) The classification of rock masses included the use of the Rock Mass Rating (RMR) and the Q-System. In the RMR method, parameters such as the rock quality design (RQD), uniaxial compressive strength (UCS), discontinuity spacing, discontinuity orientation, and groundwater conditions were assessed. The parameters were subsequently added to obtain the quality value of the rock mass (Nata and M. S., 2017, Wang et al., 2020 , Li et al., 2023 ). Rock mass classification according to the Q-System comprises factors such as the RQD, number of joint pairs (Jn), joint roughness level (Jr), joint alteration (Ja), groundwater flow (Jw), and stress reduction factor (SRF) (Narimani et al., 2023 , Sun et al., 2021 , Jixun et al., 2015 , Yuan et al., 2020 ). 3) Effect of Blasting Activities on Tunnel Stability The data were processed using RS2/Phase2 software and the finite element method (Pramono et al., 2021 , Vlachopoulos and Diederichs, 2014 , Deliveries and Benardos, 2017, Franco F. et al., 2022 , Tanjung, 2023 ). The outcome of this process was a safety factor (FK) model for both pre- and postblasting activities. The PPV before blasting was 0, while the postblasting PPV was 0. 5. Results and Discussion a. Geomechanical Information 1) Physical and mechanical properties The laboratory test results for the physical and mechanical properties of andesite basalt (porphyry) included eight parameters. These parameters were subsequently used as inputs in the Phase 2 program. Table 1 Results of Physical and Mechanical Property Testing of the Andesite Basalt (Porphyry) Property Value Unit Rock type Andesite basalt (Porphyry) Density, ρ 1335 kg/m3 Porosity 16.34 % Poisson's ratio (ν) 0.25 - Elastic modulus (E) 1257 MPa Compressive strength (σc) 48 MPa Tensile strength (σt) 0.554 MPa Cohesion (c) 75 MPa Friction angle (φ) 40.52 Degree 2) Rock mass classification Rocks were classified using two methods, namely, the RMR and Q-systems. The observed results of the rock mass classes based on the two methods were presented for both pre- and postblasting. Table 2 Observation of Rock Mass Class According to RMR and the Q-System Pre- and Postblasting Code Stasiun RMR Q-System Pre Post Pre Post 1 135.6-138.3 53 Fair (III) 51 Fair (III) 6.765 Fair (C) 5.940 Fair (C) 2 154.5-157.2 51 Fair (III) 44 Fair (III) 7.590 Fair (C) 6.518 Fair (C) 3 176.5-179.3 59 Fair (III) 56 Fair (III) 6.765 Fair (C) 6.105 Fair (C) 4 182.1–185 60 Fair (III) 60 Fair (III) 3.267 Poor (D) 3.036 Poor (D) 5 356.3-359.2 51 Fair (III) 44 Fair (III) 2.277 Poor (D) 1.238 Poor (D) 6 370.5-373.2 52 Fair (III) 46 Fair (III) 4.750 Fair (C) 3.800 Poor (D) Based on Table 2 , the quality of the rocks, both RMR and Q-system classifications, decreased pre- and postblasting. The RMR classification of the rock masses at the six observation stations indicated Fair Rock(III). Conversely, the Q-System classification showed variations, ranging from poor to fair. Stations 1 to 3 were classified as fair rock, while Stations 4 and 5 were categorized as poor rock. Station 6 was initially labeled fair rock but decreased to poor rock after the blasting event. Generally, a decrease in rock quality was observed across all stations, except for four, where the RMR classification remained constant at a value of 60. b. Ground Vibration Observation from Blasting 1) Blasting Pattern, PPV Each Station The following are the maximum PPV measurements at each observation station. These measurements were crucial in assessing the impact of blasting activities on the surrounding environment. Each blasting pattern varied across stations 1–6, leading to differences in the maximum PPV for each station. The same blasting agent was used at only stations 5 and 6, both of which used 8.8 kg of material. Additionally, each station had a total explosive value of 550 kg (Fig. 3 ). An increase in the blasting agent weight correlated with a corresponding increase in the PPV produced. This observation is depicted in the graph showing the relationship between the blasting agent weight and the maximum PPV (refer to Fig. 4 ). Despite a small R 2 value of 50%, these findings still reflected real-world scenarios (Hosseinzadeh Gharehgheshlag and Alipour, 2020). In patterns 4, 5, and 6, the most significant decrease in safety factors was observed at Station 6, accompanied by the highest tremor recorded at 1.1220 m/s 2 . Pattern 6, using 8.8 kg per delay and a total explosive load of 550 kg, showed the most substantial decrease in safety factor values compared to pattern 5. This phenomenon can be attributed to the fact that a shorter delay results in greater vibration than a longer delay time (Ren et al., 2023 , Choi and Lee, 2021 , Rao and Huang, 2023 , He et al., 2022 , Hu et al., 2021 ). The observation showed six distinct blasting patterns and geometries, as depicted in Fig. 3 . Additionally, the blasting agent weight per delay (kg) varied for each blasting pattern. The excavation activity aimed to achieve tunnel dimensions with a floor width of 7.2 m and a gallery height of 6.3 m. 2) Safety factor of the tunnel The provided model depicts the safety factor for the tunnel at each observation station, featuring four distinct observation points labeled A, B, C, and D within each model. This model serves as a critical tool for assessing the stability and safety of tunnel infrastructure. At station 1, the safety factor values at points A and C decreased, while those at points B and D remained unchanged. Specifically, at point A, the value decreased from 2.53 to 2.21 (0.32 difference), and at C, there was a reduction from 3.47 to 3.16 (0.31 difference). Moving to Station 2, a decrease was observed at points A and C. Point A’s value decreased from 2.53 to 2.21 (0.32 difference), and at point C, there was a decrease from 3.16 to 2.84 (0.34 difference), while points B and D remained unchanged. Station 3 showed decreases at points A, B, and C, with decreases from 2.51 to 2.21 (0.30), from 1.89 to 1.58 (0.31), and from 3.47 to 3.16 (0.31), respectively, while point D did not change. At station 4, only point C experienced a change, with a decrease from 3.16 to 2.84 (0.42), while points A, B, and D remained constant. Station 5 experienced a decrease in the safety factor at points A, B, and C, with no change at point D. Point A witnessed a decrease from 2.53 to 2.21 (a reduction of 0.32), while at point B, the value decreased from 1.89 to 1.58 (a decrease of 0.31). Similarly, at point C, there was a decrease from 3.16 to 2.84 (a reduction of 0.32). Finally, at Station 6, the safety factors decreased at points A, B, and C. Point A decreased from 2.53 to 1.58 (0.95), point B decreased from 1.89 to 1.26 (0.73), and C decreased from 3.47 to 2.21 (1.26). Point D showed no change in the safety factor. 3) Recapitulation Data Based on the observations from the six stations, the safety factor was within the range of 1.26 to 6.00. A significant decrease was observed at certain points after the explosion, specifically at points A, B, and C, as depicted in Fig. 8 . However, at point D, there was no change in the safety factor before or after blasting. Hoek asserted that a safety factor greater than 1 was considered stable. For the safety factor of a water tunnel, a minimum range of 1.3 to 1.5 was recommended (Paul et al., 2014 , Vlachopoulos and Diederichs, 2014 , Deliveries and Benardos, 2017, Naseri and Bahrani, 2019 ). 6. Conclusion In conclusion, Fair Rock class (III) rocks were identified at the six observation stations based on the classification of rock masses according to RMR 1989. There was a significant decrease in the weight of the rock mass before and after blasting at each station. According to the grouping of rock masses using the Q-System, stations 135.6-138.3, 154.5-157.2, and 176.5-179.3 belonged to the Fair (C) class, while stations 182.1–185 and 356.3-359.2 were classified as the Poor (D) class. At station 370.5-373.2, the typhoon was initially classified as Fair class (C) before detonation and then changed to Poor (D) after blasting. According to the analysis of the observations from the six stations, the safety factor ranged from 1.26 to 6.00. A difference in the decrease at certain points after the explosion was observed, such as points A, B, and C, as shown in Fig. 8 . However, at point D, there was no change in the safety factor value either pre- or postdetonation. A greater blasting agent weight per delay resulted in increased vibration across the six patterns. The most significant decrease in safety factors occurred only in pattern 6, with the highest tremor recorded at 1.1220 m/s 2 . Comparing patterns 5 and 6 with the same blasting agent weight per delay of 8.8 kg and equal explosive load of 550 kg showed that the highest decrease in safety factor values occurred in pattern 6. This phenomenon can be attributed to the fact that a shorter delay produces greater vibration than a longer delay time. List of symbols ρ Density ν Poisson's ratio E Elastic modulus σc Compressive strength σt Tensile strength c Cohesion φ Friction angle Declarations Acknowledgments. The author expresses gratitude to the engineers and management of PT. We thank Kerinci Merangin Hydro for providing invaluable guidance and assistance throughout this project. Conflict of interest : The authors confirm that there are no conflicts of interest to report. Notice of Disclaimer. The funders played no role in influencing the study's design; data collection, analysis, or interpretation; report writing; or the decision to publish the results. The statements presented herein solely reflect the writers' opinions and may not necessarily represent the views of any funding source. Author contributions The authors' contributions to the project are outlined as follows. Refky Adi Nata was responsible for the original draft writing, conceptualization, data curation, and visualization. Gaofeng Ren was engaged in the original draft writing, supervision, validation, methodology, data curation, and conceptualization. Ardhymanto Am Tanjung managed the project, allocated resources, handled the software, conducted the investigation, secured the funding, performed the formal analysis, and contributed to the methodology. Fadhilah, Bambang Heriyadi, Verra Syahmer, and Azri Rizki Pratama all contributed to writing, reviewing, and editing and were actively engaged in validation and supervision. References Brown, E.T., 2015. Rock engineering design of post-tensioned anchors for dams – A review. 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Stability evaluation method of large cross-section tunnel considering modification of thickness-span ratio in mechanized operation. RS 2, 197–210. https://doi.org/10.1108/RS-03-2023-0011 Zhang, Y., Wang, J., Liu, F., Xia, H., 2022. Mechanism and Sensitivity Analysis of Collapse in Large Section Mountain Neighborhood Tunnels. Front. Earth Sci. 10, 904655. https://doi.org/10.3389/feart.2022.904655 Zhang, Y.-J., Su, K., Zhu, H.-Z., Qian, Z.-D., Wu, H.-G., 2020. Installation Time of an Initial Support for Tunnel Excavation upon the Safety Factors of Surrounding Rock. Applied Sciences 10, 5653. https://doi.org/10.3390/app10165653 Zhenxiang, X., n.d. Eine Methode fur die Tunnelbemessung mit an Ort und Stelle gemessenen Daten. Additional Declarations No competing interests reported. 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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-3895685","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":269141141,"identity":"86537ed5-e7cd-495f-9be1-df8883b1e09d","order_by":0,"name":"Refky Adi Nata","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIie3ROwrCQBCA4YkD2kxIu0KIV0gIaGHhVZQUKb2AhSCsnSfQe1iuDKxNDmAhqAhWClZiJcYXWm2wE9y/CCHMB7MbAJvtJ3O2+QPJQ/X+pshIML6Tqky+JBDqDwIm0hgOMKZe04+1p9CdLsEbKkftDcTPGBPSKdU1ArrZDkTWhtnYQIToMlOZqb4a5EQywAKATYuJ2haZLkyxxAepFRKBmOSTFJafJCwklGA0GaUkNIazidxRlHX65rNUGMX+1Gx50tmsD3IZBHPmo+nGbpVea6jHT3T6BSAfOb/fVeG0zWaz/V9Xpq9GCRHX+hwAAAAASUVORK5CYII=","orcid":"","institution":"Wuhan University of Technology","correspondingAuthor":true,"prefix":"","firstName":"Refky","middleName":"Adi","lastName":"Nata","suffix":""},{"id":269141142,"identity":"6ed16882-ae51-486a-8d04-a5a1d64ed353","order_by":1,"name":"Gaofeng Ren","email":"","orcid":"","institution":"Wuhan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Gaofeng","middleName":"","lastName":"Ren","suffix":""},{"id":269141143,"identity":"13fd73f8-e755-465d-b331-2eda27c2217d","order_by":2,"name":"Ardhymanto Am Tanjung","email":"","orcid":"","institution":"Universitas Negeri Padang","correspondingAuthor":false,"prefix":"","firstName":"Ardhymanto","middleName":"Am","lastName":"Tanjung","suffix":""},{"id":269141144,"identity":"082d0c89-e617-4e4b-95b9-f355cdc7fe29","order_by":3,"name":"Fadhilah Muzer","email":"","orcid":"","institution":"Universitas Negeri Padang","correspondingAuthor":false,"prefix":"","firstName":"Fadhilah","middleName":"","lastName":"Muzer","suffix":""},{"id":269141145,"identity":"2dce7e8e-5a1d-42ff-9c5f-e11358152a66","order_by":4,"name":"Bambang Heriyadi","email":"","orcid":"","institution":"Universitas Negeri Padang","correspondingAuthor":false,"prefix":"","firstName":"Bambang","middleName":"","lastName":"Heriyadi","suffix":""},{"id":269141146,"identity":"0fcfaf5a-1f72-4548-97df-a304d88c4720","order_by":5,"name":"Verra Syahmer","email":"","orcid":"","institution":"Agro Industrial Engineering ATIP Padang Polytechnic","correspondingAuthor":false,"prefix":"","firstName":"Verra","middleName":"","lastName":"Syahmer","suffix":""},{"id":269141147,"identity":"fd96a367-4519-4ded-bb9a-90d4a91edd51","order_by":6,"name":"Azri Rizki Pratama","email":"","orcid":"","institution":"STTIND Padang","correspondingAuthor":false,"prefix":"","firstName":"Azri","middleName":"Rizki","lastName":"Pratama","suffix":""}],"badges":[],"createdAt":"2024-01-25 02:14:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3895685/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3895685/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":50343987,"identity":"b86a9a9e-4784-4405-a6cf-f63c47e4226b","added_by":"auto","created_at":"2024-01-30 05:52:18","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":410206,"visible":true,"origin":"","legend":"\u003cp\u003eMap of PT. Kerinci Merangin Hydro\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/85382ea96895200030a26ba7.png"},{"id":50344409,"identity":"9d8fb22d-c5a8-4296-8f9d-54c51ab559af","added_by":"auto","created_at":"2024-01-30 06:00:18","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":557221,"visible":true,"origin":"","legend":"\u003cp\u003eStudy Flow Chart\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/6c155477c9d5a3ae4dae50b2.png"},{"id":50344724,"identity":"6e535a51-ae0d-40e4-a4b1-4dfe22e0900f","added_by":"auto","created_at":"2024-01-30 06:08:19","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":171461,"visible":true,"origin":"","legend":"\u003cp\u003eBlasting Pattern Information Stations 1 to 6\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/724d34621f2543ebde4de158.png"},{"id":50343984,"identity":"9393e806-2829-4ec7-ac72-f277fe23deea","added_by":"auto","created_at":"2024-01-30 05:52:18","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":10035,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between the Blasting Agent Weight and the PPV Maximum\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/daf989fe4b1afc23bccc0ccb.png"},{"id":50343986,"identity":"523555a9-0f6b-4f3c-8ec0-6428d7eb9238","added_by":"auto","created_at":"2024-01-30 05:52:18","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":248174,"visible":true,"origin":"","legend":"\u003cp\u003eStation Models 1 and 2 Pre- and Post-Blasting Activities\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/a2e26af25633c81b8c9f533d.png"},{"id":50343988,"identity":"79221979-f23e-4ff4-8350-154ff19329d8","added_by":"auto","created_at":"2024-01-30 05:52:19","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":244675,"visible":true,"origin":"","legend":"\u003cp\u003eStation Models 3 and 4 Pre- and Post-Blasting Activities\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/359343560681de4b1c9e557d.png"},{"id":50343991,"identity":"5c690d0d-15b6-44ea-aeb5-ca0a23c119a5","added_by":"auto","created_at":"2024-01-30 05:52:19","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":244826,"visible":true,"origin":"","legend":"\u003cp\u003eStation Models 5 and 6 Pre- and Post-Blasting Activities\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/9bd623cd5fd3248f7ca87a44.png"},{"id":50344410,"identity":"6a6fd523-4955-49c5-9a4a-b8177cf5a5cb","added_by":"auto","created_at":"2024-01-30 06:00:19","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":27251,"visible":true,"origin":"","legend":"\u003cp\u003eGraph of Safety Factor Values Pre- and Post-Blasting at Each Station\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/79fef186f18030315c5d5880.png"},{"id":55265567,"identity":"e7249862-a031-4cdf-952d-f5cd0df7c27a","added_by":"auto","created_at":"2024-04-25 02:07:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2074211,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3895685/v1/e6f2c69a-65e9-4539-9345-df71d38ed602.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eImplications of Blasting-Induced Vibration on the Stability of Hydroelectric Power Tunnel\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAn adit tunnel is a horizontal opening used for accessing a headrace in a hydroelectric power tunnel. Various factors contribute to ensuring tunnel stability, with a particular focus on maintaining stability by limiting the maximum total displacement to 0.2 mm/day (Zhenxiang, n.d., Wang, et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Y. Zhang et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Zhang et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Additionally, a safety factor of 1.5 or higher is maintained for electric hydropower (Brown, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2015\u003c/span\u003e, Hoek and Brown, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Hu et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Zhang et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Nedevska et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePT. Kerinci Merangin Hidro is actively engaged in the construction of hydropower plants, with a focus on creating two types of tunnels. The main tunnel, referred to as the headrace, serves as the primary water drainage site, while the auxiliary tunnel (adit) functions as an access point to the main tunnel. Both tunnels are constructed using drilling and blasting methods.\u003c/p\u003e \u003cp\u003eThe stability of a tunnel is considered to be safe against the effect of detonation when safety factor calculations reveal minimal differences (Jasipto et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). This is crucial because the initiation of vibration during blasting is influenced by several factors, such as the number of fillings, delay number placement, delay interval, and correlation of explosive charges (Huang et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Ittner et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Ma et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Soltani-Mohammadi et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, B. Zhang et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDuring blasting activities with a target progress rate of 50 m in a month, high explosives are commonly used between 500 and 600 PCS days. However, this method leads to vibrations that negatively impact tunnel stability, causing the formation of new cracks in walls. Direct observations made during the initial STA showed signs of collapse, despite the tunnel having been in a safe condition previously.\u003c/p\u003e"},{"header":"2. Area and Geological Observation","content":"\u003cp\u003e \u003cb\u003eThe\u003c/b\u003e Kerinci Merangin Hydro hydropower plant is located on the southwest slope of Bukit Barisan on Sumatra Island. The plant site was approximately 448 km southwest of Jambi Municipality, capital of Jambi Province, with coordinates of 2\u0026deg;14\u0026prime;5.72\" \u0026minus;\u0026thinsp;2\u0026deg;11\u0026prime;26.4\" South Latitude and 101\u0026deg;40\u0026prime;18.54\" \u0026ndash; 101\u0026deg;45\u0026prime;44.94\" East Longitude.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe 450 MW Kerinci hydropower plant comprises several main components, including a regulating weir, intake dam, headrace tunnel, headrace surge shaft, penstock, and powerhouse. This hydropower plant features four turbines designed for a franchise type and a headrace tunnel length of \u0026plusmn;\u0026thinsp;14 km, as do the other three adits within the project. Adit Tunnel 1 had a length of \u0026plusmn;\u0026thinsp;504 m, Tunnel 2 measured approximately 912 m, and Adit 4 spanned\u0026thinsp;\u0026plusmn;\u0026thinsp;409 m.\u003c/p\u003e"},{"header":"3. Geological Structure","content":"\u003cp\u003eThe project site, located approximately 20 km southwest, was positioned outside the Semangko fault, an active fault system. Despite being outside the fault area, the regional stress distribution in the bedrock was potentially connected to the Sumatran Fault System. However, detailed in situ stress conditions were challenging to determine for technical reasons during this investigation. Geological investigations further showed that the rocks surrounding the powerhouse tunnel were Batusabak and sandstone in the Asai Formation. The average strike and dip values, measured at N45\u0026deg;W/40\u0026deg;SW, provided a representative orientation of the layers at the underground tunnel site.\u003c/p\u003e"},{"header":"4. Methodology","content":"\u003cp\u003e\u003cstrong\u003ea. Data\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo address the study objectives, essential data were the primary input for the analysis process. The required data included various parameters, including the RMR, such as the RQD, discontinuity spacing, conditions, orientation, and groundwater, as well as Q-System indicators, such as the RQD, number of joint pairs (Jn), joint roughness level (Jr), joint alteration (Ja), groundwater flow (Jw), and stress reduction factor (SRF). The additional data included the actual peak particle velocity (PPV), geological structure measurements in the field, tunnel geometry and blasting pattern. Secondary data, including geological data, physical and mechanical properties of rocks, explosive specifications, and regional geologic maps, were also essential for comprehensive analysis.\u003c/p\u003e\n\u003cp\u003eVarious instruments were used to collect data, with the Vibration Measuring Device (Blastmate III) playing a crucial role in reading vibrations generated during blasting activities. The geological compass measured the strike/dip direction of structures (joints) on the walls of holes and axial tunnels. GPS was used to plot coordinates at each data collection point (STA), while a geological hammer was used to facilitate rock sampling. Furthermore, a meter was used as a measuring device for determining the distance from the blasting site to the observation location.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb. Data Processing Methods\u003c/strong\u003e\u003c/p\u003e\n\u003ch3\u003e1) Peak Particle Velocity (PPV)\u003c/h3\u003e\n\u003cp\u003eThe data were processed using Blastware 10.7 instant software, which included the input of information such as longitudinal, vertical, and transverse wave recordings. The other data included the peak particle acceleration, airblast recording, measuring distance, and number of explosives per pit. The program subsequently generated a square root graph based on the values of the k and m coefficients, which was instrumental in determining the vibration PPV at various distances.\u003c/p\u003e\n\u003ch3\u003e2) Rock mass classification (dup: abstract ?)\u003c/h3\u003e\n\u003cp\u003eThe classification of rock masses included the use of the Rock Mass Rating (RMR) and the Q-System. In the RMR method, parameters such as the rock quality design (RQD), uniaxial compressive strength (UCS), discontinuity spacing, discontinuity orientation, and groundwater conditions were assessed. The parameters were subsequently added to obtain the quality value of the rock mass (Nata and M. S., 2017, Wang et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Li et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Rock mass classification according to the Q-System comprises factors such as the RQD, number of joint pairs (Jn), joint roughness level (Jr), joint alteration (Ja), groundwater flow (Jw), and stress reduction factor (SRF) (Narimani et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Sun et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2021\u003c/span\u003e, Jixun et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2015\u003c/span\u003e, Yuan et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003e3) Effect of Blasting Activities on Tunnel Stability\u003c/h3\u003e\n\u003cp\u003eThe data were processed using RS2/Phase2 software and the finite element method (Pramono et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e, Vlachopoulos and Diederichs, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, Deliveries and Benardos, 2017, Franco F. et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Tanjung, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The outcome of this process was a safety factor (FK) model for both pre- and postblasting activities. The PPV before blasting was 0, while the postblasting PPV was 0.\u003c/p\u003e "},{"header":"5. Results and Discussion","content":"\u003cp\u003e \u003cb\u003ea. Geomechanical Information\u003c/b\u003e \u003c/p\u003e \n\u003ch3\u003e1) Physical and mechanical properties\u003c/h3\u003e\n\u003cp\u003eThe laboratory test results for the physical and mechanical properties of andesite basalt (porphyry) included eight parameters. These parameters were subsequently used as inputs in the Phase 2 program.\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\u003eResults of Physical and Mechanical Property Testing of the Andesite Basalt (Porphyry)\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\u003eProperty\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\u003eUnit\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRock type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eAndesite basalt (Porphyry)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDensity, ρ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1335\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ekg/m3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePorosity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePoisson's ratio (ν)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElastic modulus (E)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1257\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompressive strength (σc)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTensile strength (σt)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.554\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCohesion (c)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriction angle (φ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDegree\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003e2) Rock mass classification\u003c/h3\u003e\n\u003cp\u003eRocks were classified using two methods, namely, the RMR and Q-systems. The observed results of the rock mass classes based on the two methods were presented for both pre- and postblasting.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eObservation of Rock Mass Class According to RMR and the Q-System Pre- and Postblasting\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCode\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eStasiun\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c6\" namest=\"c3\"\u003e \u003cp\u003eRMR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c10\" namest=\"c7\"\u003e \u003cp\u003eQ-System\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003ePre\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003ePost\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003ePre\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003ePost\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e135.6-138.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.765\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e5.940\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e154.5-157.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7.590\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e6.518\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e176.5-179.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.765\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e6.105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e182.1\u0026ndash;185\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3.267\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePoor (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3.036\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003ePoor (D)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e356.3-359.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2.277\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePoor (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.238\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003ePoor (D)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e370.5-373.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFair (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e4.750\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFair (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3.800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003ePoor (D)\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\u003eBased on Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the quality of the rocks, both RMR and Q-system classifications, decreased pre- and postblasting. The RMR classification of the rock masses at the six observation stations indicated Fair Rock(III). Conversely, the Q-System classification showed variations, ranging from poor to fair. Stations 1 to 3 were classified as fair rock, while Stations 4 and 5 were categorized as poor rock. Station 6 was initially labeled fair rock but decreased to poor rock after the blasting event. Generally, a decrease in rock quality was observed across all stations, except for four, where the RMR classification remained constant at a value of 60.\u003c/p\u003e \u003cp\u003e \u003cb\u003eb. Ground Vibration Observation from Blasting\u003c/b\u003e \u003c/p\u003e \n\u003ch3\u003e1) Blasting Pattern, PPV Each Station\u003c/h3\u003e\n\u003cp\u003eThe following are the maximum PPV measurements at each observation station. These measurements were crucial in assessing the impact of blasting activities on the surrounding environment.\u003c/p\u003e \u003cp\u003eEach blasting pattern varied across stations 1\u0026ndash;6, leading to differences in the maximum PPV for each station. The same blasting agent was used at only stations 5 and 6, both of which used 8.8 kg of material. Additionally, each station had a total explosive value of 550 kg (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAn increase in the blasting agent weight correlated with a corresponding increase in the PPV produced. This observation is depicted in the graph showing the relationship between the blasting agent weight and the maximum PPV (refer to Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Despite a small R\u003csup\u003e2\u003c/sup\u003e value of 50%, these findings still reflected real-world scenarios (Hosseinzadeh Gharehgheshlag and Alipour, 2020).\u003c/p\u003e\u003cp\u003eIn patterns 4, 5, and 6, the most significant decrease in safety factors was observed at Station 6, accompanied by the highest tremor recorded at 1.1220 m/s\u003csup\u003e2\u003c/sup\u003e. Pattern 6, using 8.8 kg per delay and a total explosive load of 550 kg, showed the most substantial decrease in safety factor values compared to pattern 5. This phenomenon can be attributed to the fact that a shorter delay results in greater vibration than a longer delay time (Ren et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Choi and Lee, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e, Rao and Huang, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, He et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Hu et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe observation showed six distinct blasting patterns and geometries, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Additionally, the blasting agent weight per delay (kg) varied for each blasting pattern. The excavation activity aimed to achieve tunnel dimensions with a floor width of 7.2 m and a gallery height of 6.3 m.\u003c/p\u003e\n\u003ch3\u003e2) Safety factor of the tunnel\u003c/h3\u003e\n\u003cp\u003eThe provided model depicts the safety factor for the tunnel at each observation station, featuring four distinct observation points labeled A, B, C, and D within each model. This model serves as a critical tool for assessing the stability and safety of tunnel infrastructure.\u003c/p\u003e\u003cp\u003eAt station 1, the safety factor values at points A and C decreased, while those at points B and D remained unchanged. Specifically, at point A, the value decreased from 2.53 to 2.21 (0.32 difference), and at C, there was a reduction from 3.47 to 3.16 (0.31 difference). Moving to Station 2, a decrease was observed at points A and C. Point A\u0026rsquo;s value decreased from 2.53 to 2.21 (0.32 difference), and at point C, there was a decrease from 3.16 to 2.84 (0.34 difference), while points B and D remained unchanged.\u003c/p\u003e\u003cp\u003eStation 3 showed decreases at points A, B, and C, with decreases from 2.51 to 2.21 (0.30), from 1.89 to 1.58 (0.31), and from 3.47 to 3.16 (0.31), respectively, while point D did not change. At station 4, only point C experienced a change, with a decrease from 3.16 to 2.84 (0.42), while points A, B, and D remained constant.\u003c/p\u003e\u003cp\u003eStation 5 experienced a decrease in the safety factor at points A, B, and C, with no change at point D. Point A witnessed a decrease from 2.53 to 2.21 (a reduction of 0.32), while at point B, the value decreased from 1.89 to 1.58 (a decrease of 0.31). Similarly, at point C, there was a decrease from 3.16 to 2.84 (a reduction of 0.32). Finally, at Station 6, the safety factors decreased at points A, B, and C. Point A decreased from 2.53 to 1.58 (0.95), point B decreased from 1.89 to 1.26 (0.73), and C decreased from 3.47 to 2.21 (1.26). Point D showed no change in the safety factor.\u003c/p\u003e\n\u003ch3\u003e3) Recapitulation Data\u003c/h3\u003e\n\u003cp\u003eBased on the observations from the six stations, the safety factor was within the range of 1.26 to 6.00. A significant decrease was observed at certain points after the explosion, specifically at points A, B, and C, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e8\u003c/span\u003e. However, at point D, there was no change in the safety factor before or after blasting. Hoek asserted that a safety factor greater than 1 was considered stable. For the safety factor of a water tunnel, a minimum range of 1.3 to 1.5 was recommended (Paul et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, Vlachopoulos and Diederichs, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, Deliveries and Benardos, 2017, Naseri and Bahrani, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e "},{"header":"6. Conclusion","content":"\u003cp\u003eIn conclusion, Fair Rock class (III) rocks were identified at the six observation stations based on the classification of rock masses according to RMR 1989. There was a significant decrease in the weight of the rock mass before and after blasting at each station. According to the grouping of rock masses using the Q-System, stations 135.6-138.3, 154.5-157.2, and 176.5-179.3 belonged to the Fair (C) class, while stations 182.1\u0026ndash;185 and 356.3-359.2 were classified as the Poor (D) class. At station 370.5-373.2, the typhoon was initially classified as Fair class (C) before detonation and then changed to Poor (D) after blasting.\u003c/p\u003e \u003cp\u003eAccording to the analysis of the observations from the six stations, the safety factor ranged from 1.26 to 6.00. A difference in the decrease at certain points after the explosion was observed, such as points A, B, and C, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e8\u003c/span\u003e. However, at point D, there was no change in the safety factor value either pre- or postdetonation.\u003c/p\u003e \u003cp\u003eA greater blasting agent weight per delay resulted in increased vibration across the six patterns. The most significant decrease in safety factors occurred only in pattern 6, with the highest tremor recorded at 1.1220 m/s\u003csup\u003e2\u003c/sup\u003e. Comparing patterns 5 and 6 with the same blasting agent weight per delay of 8.8 kg and equal explosive load of 550 kg showed that the highest decrease in safety factor values occurred in pattern 6. This phenomenon can be attributed to the fact that a shorter delay produces greater vibration than a longer delay time.\u003c/p\u003e"},{"header":"List of symbols","content":"\u003cp\u003e\u0026rho; \u0026nbsp;Density\u003c/p\u003e\n\u003cp\u003e\u0026nu; \u0026nbsp;Poisson\u0026apos;s ratio\u003c/p\u003e\n\u003cp\u003eE \u0026nbsp;Elastic modulus\u003c/p\u003e\n\u003cp\u003e\u0026sigma;c Compressive strength\u003c/p\u003e\n\u003cp\u003e\u0026sigma;t \u0026nbsp;Tensile strength\u003c/p\u003e\n\u003cp\u003ec \u0026nbsp;Cohesion\u003c/p\u003e\n\u003cp\u003e\u0026phi; \u0026nbsp;Friction angle\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments.\u003c/strong\u003e The author expresses gratitude to the engineers and management of PT. We thank Kerinci Merangin Hydro for providing invaluable guidance and assistance throughout this project.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e: The authors confirm that there are no conflicts of interest to report.\u003c/p\u003e\n\u003cp\u003eNotice of Disclaimer. The funders played no role in influencing the study\u0026apos;s design; data collection, analysis, or interpretation; report writing; or the decision to publish the results. The statements presented herein solely reflect the writers\u0026apos; opinions and may not necessarily represent the views of any funding source.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors\u0026apos; contributions to the project are outlined as follows. Refky Adi Nata was responsible for the original draft writing, conceptualization, data curation, and visualization. Gaofeng Ren was engaged in the original draft writing, supervision, validation, methodology, data curation, and conceptualization. Ardhymanto Am Tanjung managed the project, allocated resources, handled the software, conducted the investigation, secured the funding, performed the formal analysis, and contributed to the methodology. Fadhilah, Bambang Heriyadi, Verra Syahmer, and Azri Rizki Pratama all contributed to writing, reviewing, and editing and were actively engaged in validation and supervision.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBrown, E.T., 2015. Rock engineering design of post-tensioned anchors for dams \u0026ndash; A review. Journal of Rock Mechanics and Geotechnical Engineering 7, 1\u0026ndash;13. https://doi.org/10.1016/j.jrmge.2014.08.001\u003c/li\u003e\n\u003cli\u003eChoi, Y.-H., Lee, S.S., 2021. Predictive Modeling for Blasting-Induced Vibrations from Open-Pit Excavations. 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Shock and Vibration 2022, 1\u0026ndash;11. https://doi.org/10.1155/2022/3836086\u003c/li\u003e\n\u003cli\u003eZhang, J., Liu, Y., Yan, B., 2023. Stability evaluation method of large cross-section tunnel considering modification of thickness-span ratio in mechanized operation. RS 2, 197\u0026ndash;210. https://doi.org/10.1108/RS-03-2023-0011\u003c/li\u003e\n\u003cli\u003eZhang, Y., Wang, J., Liu, F., Xia, H., 2022. Mechanism and Sensitivity Analysis of Collapse in Large Section Mountain Neighborhood Tunnels. Front. Earth Sci. 10, 904655. https://doi.org/10.3389/feart.2022.904655\u003c/li\u003e\n\u003cli\u003eZhang, Y.-J., Su, K., Zhu, H.-Z., Qian, Z.-D., Wu, H.-G., 2020. Installation Time of an Initial Support for Tunnel Excavation upon the Safety Factors of Surrounding Rock. Applied Sciences 10, 5653. https://doi.org/10.3390/app10165653\u003c/li\u003e\n\u003cli\u003eZhenxiang, X., n.d. Eine Methode fur die Tunnelbemessung mit an Ort und Stelle gemessenen Daten.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"blasting, safety factor, vibration, tunnel, hydropower plants","lastPublishedDoi":"10.21203/rs.3.rs-3895685/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3895685/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAn adit tunnel is a horizontal opening used for accessing a headrace in a hydroelectric power tunnel. PT. Kerinci Merangin Hidro is actively engaged in the construction of hydropower plants, with a focus on creating two types of tunnels. During blasting activities with a target progress rate of 50 m in a month, high explosives are commonly used between 500 and 600 PCS days. However, this method leads to vibrations that negatively impact tunnel stability, causing the formation of new cracks in walls. Data processing was conducted using Blastware 10.7 instant software, RS2/Phase2 software and the finite element method. The classification of rock masses included the use of the Rock Mass Rating (RMR) and the Q-System. The research results showed that Fair Rock class (III) rocks were identified at the six observation stations based on the classification of rock masses according to RMR 1989. There was a significant decrease in the weight of the rock mass before and after blasting at each station. The safety factor ranged from 1.26 to 6.00. A greater blasting agent weight per delay resulted in increased vibration across the six patterns. The most significant decrease in safety factors occurred only in pattern 6, with the highest tremor recorded at 1.1220 m/s\u003csup\u003e2\u003c/sup\u003e. Comparing patterns 5 and 6 with the same blasting agent weight per delay of 8.8 kg and equal explosive load of 550 kg showed that the highest decrease in safety factor values occurred in pattern 6. This phenomenon can be attributed to the fact that a shorter delay produces greater vibration than a longer delay time.\u003c/p\u003e","manuscriptTitle":"Implications of Blasting-Induced Vibration on the Stability of Hydroelectric Power Tunnel","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-30 05:52:14","doi":"10.21203/rs.3.rs-3895685/v1","editorialEvents":[{"type":"communityComments","content":1}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"28e778f0-2b89-487e-a102-b1a6b4839a7c","owner":[],"postedDate":"January 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-24T11:00:35+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-30 05:52:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3895685","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3895685","identity":"rs-3895685","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}