Spatial distribution of excess pore water pressure and slurry infiltration zone in slurry shield tunneling

In the construction of slurry shield tunneling, the infiltration of slurry will cause excess pore water pressure in the surrounding soil. The distribution of excess pore water pressure and slurry infiltration zone are closely related to the stability of the tunnel face. Considering the influence of cutter head rotation and slurry specific gravity on pressure boundary conditions, this study proposed a multi-field coupling model to describe the dynamic transmission of excess pore water pressure and distribution of slurry infiltration range in three-dimensional. The temporal and spatial variation of soil pores characteristics parameters and slurry rheological properties owing to the deposition and diffusion of slurry particles is considered. The proposed model is verified by the in-situ testing measurements from in Beijing East Sixth Ring Road reconstruction project. In the prediction results, the spatial distribution of excess pore water pressure around the tunnel face appears bubble-shaped, and the shape of the slurry infiltration zone is close to flattened cake. The range of pressure dissipation and the thickness of particles infiltration zone are positively correlated with soil permeability coefficient, slurry pressure, while negatively correlated with the mass concentration of slurry. In the cases of low-permeability soil, appropriately increasing the content of slurry particles can improve the compactness of the filter cake.