English：

When shield tunneling in viscous formations, blockage is prone to occur, resulting in theformation of mud cakes on the cutterhead and cutting tools. Dispersing agents are often used todecompose the mud cakes. To analyze the decomposition characteristics of mud cakes,taking the muddysiltstone in the Guangzhou area as the research object, a mud cake pressing device and a mud cakedecomposition instrument are developed, and the influence of dispersing agent and bentonite on thedecomposition of mud cakes through mud cake decomposition experiments is analyzed. Research showsthat the decomposition of mud cake in water can be divided into initial stage, rapid decomposition stage,and stable stage. In the initial stage, the mud cake absorbs water first and then decomposes, the overallchange in the quality of mud cake decomposition is relatively small. During the rapid decomposition stage,the quality of mud cake decomposition increases rapidly. In the stable stage, the quality of mud cakedecomposition basically does not increase. Soaking the mud cake in a dispersing agent solution cansignificantly improve the decomposition rate of the mud cake. The higher the concentration of dispersingagent, the higher the decomposition rate of the mud cake, and the mud cake quality will not increase inthe initial stage of mud cake decomposition. When the mud cake decomposes in a bentonite solution, thedecomposition mass of the mud cake gradually decreases and then tends to stabilize, and thedecomposition mass of the mud cake is negative, that is, the mud cake mass increases,which indicatesthat the presence of bentonite can significantly inhibit the decomposition of the mud cake.