Influence of Shield Slurry Property on Filter Cake Quality in Sand Stratum

Slurry preparation and pressure maintenance of slurry balance shield should be carefully treated during tunneling in complex sand stratum. On basis of the slurry shield tunnel project in Fuzhou, slurry pressure was determined by two different theoretical methods. Then, an indoor test was conducted to explore the influence of constituents on slurry property. The influence of slurry properties on filter cake forming process under different slurry pressure was also analyzed through slurry penetration test. The test results indicate that the bentonite and silt soil had dominated influence on relative density, while the bentonite and CMC had dominated influence on viscosity. It is found that the water discharge, which is the index to evaluate the effect of filter cake, decreases firstly and then increases as slurry relative density increases. The water discharge also decreases as slurry viscosity increases. Meanwhile, the influence of viscosity on the water discharge was found less than that of relative density. Finally, a segmented slurry control scheme suitable for sand stratum in Fuzhou was presented.