Abstract:

In order to study the disturbance law of pore water pressure caused by slurry shield tunneling, based on the fluidsolid coupling analysis of three typical strata, the influence of vertical and lateral variation of pore water pressure in different stages of shield tunneling is studied. The concept of pore water pressure disturbance ratio is proposed and the degree of construction disturbance is evaluated. The study results show that: (1) The pore water pressure of slurry shield tunneling will decrease obviously when it passes through soft soil stratum. (2) The slurry shield tunneling will cause different degree of hydraulic accumulation effect on pore water pressure of soil in front of excavation face, which is one of the necessary conditions for the formation of filter cake and affects the disturbance of pore pressure during excavation. (3) During construction period, the disturbance of pore pressure caused by slurry balanced shield construction in different strata varies; the disturbance of pore water pressure at vault position is the largest, followed by that at arch waist, and that at arch bottom is the smallest. (4) The application of grouting pressure in construction is closely related to the disturbance degree of pore water pressure; the distribution and shape of crosssection seepage field in different strata at different excavation stages vary; the vault shows the concentration point of flow pressure; and meanwhile, the slurry shield tunneling has residual effect on pore water pressure disturbance during construction period.

Key words: slurry balanced shield, pore water pressure, construction disturbance, formation condition, fluidsolid coupling analysis