在高放废物长期的深埋过程中，处置库内产生的气体在缓冲区膨润土材料中的流动会影响到处置库的长期安全稳定，气体的运移与突破模式是关键。为深入研究这一问题，选取干密度为1.7 g/cm³的压实饱和高庙子膨润土试样进行孔隙结构分析和气体突破数值模拟。基于压汞法获得的孔隙特征参数，通过高斯随机场二相化理论、叠加理论和数学形态学图像处理方法，生成并验证了三维孔隙结构模型，然后进行了气体运移和突破过程的数值模拟，得到了包括突破路径长度、迂曲度和突破孔喉尺寸等参数。利用Young-Laplace方程计算了气体突破压力。结果表明：膨润土模型渗流路径迂曲度范围为1.98 ~3.72，孔隙网络形态复杂，气体运移路径存在多条且呈迂回曲折状态。突破孔喉尺寸在0.024 ~ 0.04 μm范围，计算得到气体突破压力在7.20 ~ 12.00 MPa，与文献中的试验值接近，进一步验证了毛细管效应主导的气-液两相流是压实饱和高庙子膨润土中气体运移的主要模式。

In the long-term deep burial process of high-level radioactive waste, the flow of gas generated within the disposal facility through the buffer zone of bentonite material is recognized as a significant factor affecting the long-term safety and stability of the repository. A critical understanding of gas migration and breakthrough patterns is thereby established. To facilitate an in-depth study of this phenomenon, a compacted saturated Gaomiaozi (GMZ) bentonite sample with a dry density of 1.7 g/cm³ was selected for pore structure analysis and numerical simulation of gas breakthrough. Three-dimensional pore structure models were generated and validated utilizing pore characteristic parameters obtained from mercury intrusion porosimetry, alongside Gaussian random field two-phase theory, superposition theory, and mathematical morphology image processing methods. Following this, numerical simulations of gas migration and breakthrough processes were conducted, resulting in the acquisition of parameters such as breakthrough path length, tortuosity, and breakthrough throat size. Gas breakthrough pressure was calculated using the Young-Laplace equation. The results indicate that the tortuosity of the seepage paths within the bentonite model ranges from 1.98 to 3.72, characterized by a complex pore network morphology and multiple meandering gas migration pathways. It is found that the breakthrough throat sizes range from 0.024 μm to 0.04 μm, leading to calculated gas breakthrough pressures between 7.20 MPa and 12.00 MPa, which closely align with the experimental values reported in the literature. This further validates that capillary-driven gas-liquid two-phase flow is established as the dominant mode of gas migration in compacted saturated GMZ bentonite.