In slurry shield

the working face is supported by the pressed slurry. So it is very important to build up a filter-cake to protect the working face

especially in highly permeable ground where the slurry is easy to penetrate the ground without allowing to build up the required support pressure. The function and quality estimate indices of filter-cake were expounded. A series of filter-cake building up tests were carried out for the Nanjing Yangtze River Tunnel with the apparatus which was developed just for the research—the influence of slurry property on filter-cake quality on the working face of slurry shield. In these tests

the ranges of grain size distribution and density of the slurries were same. As shown in the results

if the viscosity is high and the stability is good

the filter-cake will be easy to build up; it will be thin and compact; and the discharged water will be little. The result of this research is significant in the slurry shield construction.