Supporting the excavation face is the most important role for slurry in the field of engineering

such as diaphragm walls

bored piles

and slurry shield tunneling. To achieve the function

a filter cake has to be formed on the soil

and the soil and pore water pressure have to be counteracted by slurry pressure. And the essence of filter cake formation is that the slurry infiltrates in the stratum. To reveal the phenomena and laws of slurry infiltrating into the soils

a series of slurry infiltration tests is carried out on sand samples with different permeabilities. Based on the test results

three typical seepage curves are discovered

and the shapes of slurry particles accumulated on the ground surface are also divided into three types: filter cake

filter cake with an infiltrated zone

and only an infiltrated zone without filter cake. Meanwhile

a corresponding relationship is discovered between the types of slurry seepage curves and the shapes of slurry particles accumulated on the surface. In addition

the seepage discharge during slurry infiltrating into the sand reflects the type of slurry infiltration. And it can be used as a criterion to determine whether a filter cake is formed on the surface.