Gas permeability of compacted bentonite can provide the key parameters for the stability analysis and long-term safety evaluation of the buffer material,and then provide the basis for the construction of deep geological repository for high level radioactive waste.The experiments were carried out to study gas permeability of compacted bentonite with different dry density under different loading pressure and confining pressure.The results show that the gas permeability coefficient is negative quadratic function correlation with the dry density.The gas permeability remarkably decreases with the dry density.When the dry density changes from 1.4 g/cm3to 1.8 g/cm3,the gas permeability coefficient gradually reduces from 10-15m2to 10-17m2.Meanwhile,the gas permeability also corelate with loading pressure and confining pressure.It gradually reduces to a constant value with increase of confining pressure under the same rario of loading pressure and confining pressure.Measuring the gas permeability coefficient of compacted bentonite when loading pressure is more than 200 kPa,it is recommended that the ratio of pressure to confining pressure is 1:3.%研究压实膨润土气体渗透特性,可为缓冲材料稳定性分析和长期安全评价提供关键参数,进而为高放废物地质处置库的建设提供依据.针对不同压实干密度的高庙子膨润土,开展了不同加载气压围压条件下的气体渗透试验研究,结果表明:气体渗透系数与压实干密度存在二次函数负相关关系,干密度由1.4 g/cm3增大到1.8 g/cm3,其气体渗透系数从10-15m2逐渐减小到10-17m2;气体渗透性与加载气压围压也存在一定关系,一定加载气压围压比条件下,随加载围压增大,气体渗透系数变化逐渐变小至趋向稳定;针对 Φ50 mm×100 mm、压实干密度1.4~1.8 g/cm3的试样,测试大于200 kPa气压值的气体渗透系数时,推荐气压围压比采用1:3.
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