During the long term operation of a disposal repository, gas will be inevitably generated. Determination of gas permeability of compacted bentonite is of great importance for the safety assessment of the engineered barrier system. In the present work, the steady-state and residual pressure methods were employed to determine the gas permeability of GaoMiaoZi (GMZ) bentonite with consideration of variations in liquid saturation, dry density and confining pressure. Results show that, gas migration in saturated GMZ bentonite was mainly controlled by diffusion with an effective gas permeability of 1E-23 m² - 1E-25 m². While in unsaturated GMZ bentonite, significant gas flow rates could be observed, which increased stably with the increase of gas injection pressure. Klinkenberg effect was significant when gas flow through GMZ bentonite. The Klinkenberg corrected gas permeability decreased by 3.5–5.5 orders of magnitude as the liquid saturation increased from 10% to 70%. A decreasing magnitude of 1–2 orders in Klinkenberg corrected gas permeability was presented with the dry density increased from 1.5 Mg/m³ and 1.7 Mg/m³. The Klinkenberg corrected gas permeability decreased by 0–1 orders of magnitude as the confining pressure increased from 3 MPa to 7 MPa. By using the accessible porosity, gas measured intrinsic permeability could be determined with values ranged between 1E-15 m² to 4E-15 m², which was higher than the water measured one by 5 orders of magnitude. Additionally, a generalized power law was successfully adopted in this study to describe the evolution of gas relative permeability with the liquid saturation. Overall, the effective gas permeability, Klinkenberg corrected gas permeability, intrinsic and relative permeability determined in this study provided a comprehensive perspective to assess the buffering property of GMZ bentonite in multi-physical field coupling environment. The parameters obtained can be adopted in further simulation works for long-term safety analysis of the disposal repository from the viewpoint of gas migration.

在处置库的长期运行中，不可避免地会产生气体。压实膨润土的气体渗透性的确定对于工程屏障系统的安全评估非常重要。在目前的工作中，考虑到液体饱和度，干密度和围压的变化，采用稳态和残余压力方法确定高庙子（GMZ）膨润土的透气度。结果表明在饱和GMZ膨润土的是，气体迁移通过扩散用的1E-23微米的有效气体渗透率主要控制² - 1E-25米²。在不饱和GMZ膨润土中，可以观察到明显的气体流速，随着气体注入压力的增加，气体流速稳定增加。当气体流过GMZ膨润土时，克林根贝格效应非常明显。随着液体饱和度从10％增加到70％，克林肯伯格校正后的气体渗透率下降了3.5-5.5个数量级。随着干燥密度从1.5 Mg / m ³和1.7 Mg / m ³增加，在克林肯贝格校正的气体渗透率中降低了1-2个数量级。随着围压从3 MPa增加到7 MPa，克林肯伯格校正后的气体渗透率降低了0-1个数量级。通过使用可达到的孔隙率，可以测定气体测得的固有渗透率，其值范围在1E-15 m ^2之间到4E-15 m ²，这比测得的水高5个数量级。此外，这项研究成功地采用了广义幂律来描述气体相对渗透率随液体饱和度的变化。总体而言，本研究确定的有效气体渗透率，克林肯伯格校正的气体渗透率，本征和相对渗透率为评估GMZ膨润土在多物理场耦合环境中的缓冲性能提供了全面的视角。从气体迁移的角度来看，所获得的参数可用于进一步的模拟工作中以对处置库进行长期安全分析。