Multiple soil layers may be exposed simultaneously on the excavated surface of a large-diameter slurry shield. To study the formation and characteristics of mud filtration cake on the excavation surface during large-diameter slurry shield tunneling, penetration tests of mud slurries in different soils were carried out using a self-made device, and the microstructures of different mud filtration cakes were observed using scanning electron microscopy. The test results showed that there were three categories of filling forms for mud slurries permeating the soils: mud filtration cake, mud cake + permeation zone, and permeation zone; correspondingly, there were three types of filtration loss, which was mainly affected by the specific gravity of mud slurry. Finally, the porosity and the fractal dimension for the pore area of the mud filtration cake were calculated, and it is found that the fractal dimension of pore area is beneficial to classify the type of mud filtration cake.

中文翻译：

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大直径泥浆盾构隧道泥浆滤饼形成及特性的试验研究

大直径泥浆盾构的开挖面可能同时暴露多个土层。为研究大口径泥浆盾构掘进开挖面泥浆滤饼的形成及特征，采用自制装置对不同土体进行泥浆贯入试验，观察不同泥浆滤饼的微观结构使用扫描电子显微镜。试验结果表明，泥浆渗入土壤的充填形式分为泥滤饼、泥饼+渗透带和渗透带三种；相应地，滤失量分为三种，主要受泥浆比重的影响。最后，