针对掘进机在黏性地层中施工刀盘结泥饼的问题，以无锡地铁4号线某矩形顶管工程为例，通过添加不同质量的聚合物对不同含水率的渣土进行改良，测试改良前后渣土的黏附强度、不排水抗剪强度及高温环境下渣土的保水能力，并通过液塑限变化分析渣土改良的机制，借助泥饼形成风险分区图评估泥饼形成的风险与改良效果。研究表明： 1）添加聚合物和水对渣土黏附强度有一定影响，增大含水率能显著降低渣土的黏附强度，当渣土含水率为35%~45%时，添加聚合物能有效降低渣土的黏附强度； 2）含水率的增大会降低渣土的不排水抗剪强度，而添加聚合物能有效增强渣土的不排水抗剪强度，当添胶比达到0.15%后增强效果显著； 3）聚合物能提高渣土的液限和保水能力，保证渣土的流塑性满足施工需要； 4）结合泥饼形成风险分区图，比较渣土-金属界面的黏附强度和渣土的不排水抗剪强度，可以综合判断黏性渣土结泥饼的风险和改良效果。

 The present study aims to investigate the mud cake problem in a tunnel boring machine in cohesive stratum. For this, a case study is conducted on a rectangular pipe jacking project on Wuxi metro line 4 in China. Different ratios of polymer are added to soil samples with different moisture contents in order to examine their adhesion strength, undrained shear strength, and the water retaining capacity in hightemperature environment before and after soil conditioning. The mechanism of soil conditioning is analyzed by changing the liquid plastic limit. The risk of formation of mud cake and effects of soil conditioning are judged using the risk zoning map of mud cake formation. The results reveal the following: (1) An increase in water content significantly reduces the adhesion strength of soil; when the water content of soil is 35%~45%, the polymer can effectively reduce its adhesion strength. (2) An increase in water content can reduce undrained shear strength, while an increase in polymer content can effectively strengthen undrained shear strength. When the addition ratio of polymer is higher than 0.15%, its strengthening effect is significant. (3) Polymers can improve the liquid limit and water retaining capacity of the soil and also ensure fluidity. (4) The risk of mud cake formation and the conditioning effect of soil can be comprehensively examined based on the risk zoning map of mud cake formation, the adhesion strength of claymetal interface, and undrained shear strength of excavated soil.