为探究复杂高水压环境下黏土质砂土地层土压平衡盾构改良渣土渗透性变化规律，解决现有盾构改良渣土抗渗性能评判标准单一的问题，结合工程实际自主研发粗颗粒土垂直渗透试验系统，对渗透压力、渗透系数、渗透量等参数进行自动化监测及分析。通过对不同黏粒质量分数的黏土质砂土地层改良渣土进行多级水压力渗透试验，并分析渗透系数、有效应力转化率随水压力、渗透时间的变化规律，得到结论如下： 1）渗透系数变化曲线分为压缩阶段、细颗粒流失阶段、稳定阶段共3阶段； 2）黏土质砂土地层改良渣土的初始饱和状态决定了渗透系数的初始变化规律，非饱和状态先发生压缩情况导致渗透系数降低，饱和状态先发生细颗粒流失情况导致渗透系数升高； 3）将有效应力转化率20%作为改良土抗渗性能判断标准； 4）黏土质砂土地层改良土抗渗性优于砂土地层改良土。

To explore the permeability evolution of conditioned muck in clayey sandy strata under complex high water pressure conditions and address the drawback that current evaluation criteria for the impermeability of shield conditioned muck are relatively single, a self-developed vertical permeability test system for coarse-grained soils is established according to engineering practices. This system realizes automatic monitoring and analysis of parameters including seepage pressure and seepage volume. Multi-stage water pressure permeability tests are carried out on conditioned muck with different clay mass fractions in clayey sandy strata. The variation patterns of permeability coefficient and effective stress conversion rate with water pressure and seepage time are calculated and analyzed. The main conclusions are drawn as follows: (1) The variation curve of permeability coefficient is divided into three stages: compression stage, fine particle loss stage, and stable stage. (2) The initial saturation state of conditioned muck in clayey sandy strata governs its initial permeability variation. Compression occurs preferentially under unsaturated conditions and reduces the permeability coefficient; by contrast, fine particle loss takes place first under saturated conditions and leads to an increase in the permeability coefficient. (3) An effective stress conversion rate of 20% is proposed as the evaluation criterion for the impermeability of conditioned muck. (4) Conditioned muck in clayey sandy strata presents better impermeability than that in sandy strata.