Multiscale modeling of gas-induced fracturing in anisotropic clayey rocks  

作　　者：Jianxiong Yang Jianfeng Liu Zhengyuan Qin Xuhai Tang Houquan Zhang 

机构地区：[1]State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource and Hydropower,Sichuan University,Chengdu,610042,China [2]School of Resources and Safety Engineering,Wuhan Institute of Technology,Wuhan,430073,China [3]School of Civil Engineering,Wuhan University,Wuhan,430072,China [4]State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining and Technology,Xuzhou,221116,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第6期2091-2110,共20页岩石力学与岩土工程学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.12302503 and U20A20266);Scientific and Technological Research Projects in Sichuan Province,China(Grant No.2023ZYD0154).

摘　　要：In the context of repositories for nuclear waste,understanding the behavior of gas migration through clayey rocks with inherent anisotropy is crucial for assessing the safety of geological disposal facilities.The primary mechanism for gas breakthrough is the opening of micro-fractures due to high gas pressure.This occurs at gas pressures lower than the combined strength of the rock and its minimum principal stress under external loading conditions.To investigate the mechanism of microscale mode-I ruptures,it is essential to incorporate a multiscale approach that includes subcritical microcracks in the modeling framework.In this contribution,we derive the model from microstructures that contain periodically distributed microcracks within a porous material.The damage evolution law is coupled with the macroscopic poroelastic system by employing the asymptotic homogenization method and considering the inherent hydro-mechanical(HM)anisotropy at the microscale.The resulting permeability change induced by fracture opening is implicitly integrated into the gas flow equation.Verification examples are presented to validate the developed model step by step.An analysis of local macroscopic response is undertaken to underscore the influence of factors such as strain rate,initial damage,and applied stress,on the gas migration process.Numerical examples of direct tension tests are used to demonstrate the model’s efficacy in describing localized failure characteristics.Finally,the simulation results for preferential gas flow reveal the robustness of the two-scale model in explicitly depicting gas-induced fracturing in anisotropic clayey rocks.The model successfully captures the common behaviors observed in laboratory experiments,such as a sudden drop in gas injection pressure,rapid build-up of downstream gas pressure,and steady-state gas flow following gas breakthrough.

关 键 词：Deep geological repositories Mode-I microcracks Time-dependent damage Fracturing process Anisotropic rock 

分 类 号：TV223.1[水利工程—水工结构工程]