Claystone is considered as a potential host rock for radioactive waste disposal at great depth in many countries. Considerable quantity of gas can be generated in a deep geological repository (DGR) due to several processes, which may affect the integrity of the host rock and the safety of the DGR. Thus, understanding the migration of gas through the host rock is an essential requirement in developing a safety case for a deep geological disposal of radioactive waste. In this paper, a fully coupled dual porosity poroelastic model is developed to simulate the gas transport process in initially saturated claystone. The model considers the hydro-mechanical behavior for the fractured porous medium consisting of both the porous matrix (represented by the porous continuum) and fractures (represented by the fractured continuum), which are two separate and overlapping porous media. Each continuum has its own constitutive law that imposes a superimposed effect on the behavior of the fractured porous medium. The mechanical coupling between the two continua is through total stress equilibrium and strain superimposition technique, while the fluid coupling in the two continua is through water exchange term and porosity interaction. The capability of the developed dual porosity poroelastic model is evaluated by comparing the simulated results with that recorded in the laboratory gas injection tests on claystone, in which the main experimental behaviors, i.e., the major gas breakthrough, sample volume dilation, gas induced fracturing are well represented.

在许多国家，粘土被认为是用于深埋放射性废物处置的潜在主岩。深部地质处置库 (DGR) 中的多个过程可能会产生大量气体，这可能会影响主岩的完整性和 DGR 的安全性。因此，了解气体通过母岩的迁移是开发放射性废物深层地质处置安全案例的基本要求。在本文中，开发了一个完全耦合的双孔隙度多孔弹性模型来模拟初始饱和粘土岩中的气体输运过程。该模型考虑了由多孔基质（由多孔连续体表示）和裂缝（由断裂连续体表示）组成的裂缝性多孔介质的流体力学行为，它们是两个独立且重叠的多孔介质。每个连续体都有自己的本构定律，对破裂的多孔介质的行为施加叠加影响。两个连续体之间的机械耦合是通过总应力平衡和应变叠加技术，而两个连续体中的流体耦合是通过水交换项和孔隙度相互作用。通过将模拟结果与粘土岩实验室注气测试记录的结果进行比较，评估了所建立的双孔隙度多孔弹性模型的能力，其中主要的实验行为，即主气突破、样品体积膨胀、气体诱导压裂是很好的代表。每个连续体都有自己的本构定律，对破裂的多孔介质的行为施加叠加影响。两个连续体之间的机械耦合是通过总应力平衡和应变叠加技术，而两个连续体中的流体耦合是通过水交换项和孔隙度相互作用。通过将模拟结果与粘土岩实验室注气测试记录的结果进行比较，评估了所建立的双孔隙度多孔弹性模型的能力，其中主要的实验行为，即主气突破、样品体积膨胀、气体诱导压裂是很好的代表。每个连续体都有自己的本构定律，对破裂的多孔介质的行为施加叠加影响。两个连续体之间的机械耦合是通过总应力平衡和应变叠加技术，而两个连续体中的流体耦合是通过水交换项和孔隙度相互作用。通过将模拟结果与粘土岩实验室注气测试记录的结果进行比较，评估了所建立的双孔隙度多孔弹性模型的能力，其中主要的实验行为，即主气突破、样品体积膨胀、气体诱导压裂是很好的代表。而两个连续体中的流体耦合是通过水交换项和孔隙度相互作用。通过将模拟结果与粘土岩实验室注气测试记录的结果进行比较，评估了所建立的双孔隙度多孔弹性模型的能力，其中主要的实验行为，即主气突破、样品体积膨胀、气体诱导压裂是很好的代表。而两个连续体中的流体耦合是通过水交换项和孔隙度相互作用。通过将模拟结果与粘土岩实验室注气测试记录的结果进行比较，评估了所建立的双孔隙度多孔弹性模型的能力，其中主要的实验行为，即主气突破、样品体积膨胀、气体诱导压裂是很好的代表。