Hydro-mechanical and gas transport (HM-G) characterization of sand/bentonite mixture within the framework of the Gas Permeable Seal Test (GAST)

Hydro-mechanical and gas transport (HM-G) characterization of sand/bentonite mixture within the framework of the Gas Permeable Seal Test (GAST) | 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 Hydro-mechanical and gas transport (HM-G) characterization of sand/bentonite mixture within the framework of the Gas Permeable Seal Test (GAST) Erdem Toprak, Sebastia Olivella, Enrique Romero, Alessandro Fraccica, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7549999/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 13 Apr, 2026 Read the published version in Environmental Earth Sciences → Version 1 posted 14 You are reading this latest preprint version Abstract The sand/bentonite (S/B) mixture is considered as a candidate sealing and backfilling material for Switzerland’s deep geological repository (DGR). Using S/B mixtures as sealing material offers key advantages, such as higher intrinsic gas permeability and lower swelling pressure, which enhance gas transport efficiency. These properties make the S/B mixture a strong candidate for use as a gas-permeable seal within the Engineered Gas Transport System (EGTS) concept. This study investigates hydro-mechanical and gas transport (HM-G) response of the S/B mixture, incorporating the effects of dynamic compaction-induced variability in dry density. Key properties of the S/B mixture, such as porosity-dependent and strain-dependent water retention curves (WRC), effective and intrinsic water and gas permeability, and mechanical parameters, were calibrated while accounting for the multiscale heterogeneity in dry density and effective gas permeability of the system. Laboratory-scale simulations of oedometer and swelling pressure tests were conducted to support the parametrization of the mechanical model. The simulations were performed using CODE_BRIGHT, a Finite Element Method (FEM) program. Advanced geo-mechanical models, including the Barcelona Basic Model (BBM), the Barcelona Expansive Model (BExM), and strain-dependent permeability, were utilized to characterize the material behavior. GAST S/B mixture EGTS DGR design CODE_BRIGHT Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 13 Apr, 2026 Read the published version in Environmental Earth Sciences → Version 1 posted Editorial decision: Revision requested 22 Nov, 2025 Reviews received at journal 16 Nov, 2025 Reviews received at journal 13 Nov, 2025 Reviews received at journal 10 Nov, 2025 Reviews received at journal 08 Nov, 2025 Reviewers agreed at journal 16 Oct, 2025 Reviewers agreed at journal 14 Oct, 2025 Reviewers agreed at journal 13 Oct, 2025 Reviewers agreed at journal 13 Oct, 2025 Reviewers agreed at journal 11 Oct, 2025 Reviewers invited by journal 11 Oct, 2025 Editor assigned by journal 07 Sep, 2025 Submission checks completed at journal 07 Sep, 2025 First submitted to journal 06 Sep, 2025 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. 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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-7549999","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":533056781,"identity":"5531e45d-21b1-465a-bef2-33096f83896d","order_by":0,"name":"Erdem 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