3D coupled mechanical and hydraulic analysis of pore water pressure disturbed by shield tunnelling

It is a difficult problem to analyze the pore water pressure monitored in the field while tunnelling. Based on the tunnel constructed in Shanghai of China, a finite element model for shield tunnelling is established, which can study the effects of construction parameters. The model is validated by comparing the calculated results with the data monitored in the field. The effects of the construction parameters including the face thrust force, grouting pressure, excavation rate, water head at the face, cover depth and soil permeability on the maximum excess pore water pressure are analyzed. Then a fitting formula for the pore water pressure is obtained based on the calculated result. By comparison between the analytic solution and the data monitored in the field, it is obtained that the 3D coupled mechanical and hydraulic method is a good way to analyze the pore water pressure disturbed by shield tunnelling. The larger the maximum pore water pressure, the larger the ground settlement. So the pore water pressure monitored in the field can be used to analyze the fitness of the construction parameters. For Yingbinsanlu tunnelling project in Shanghai, the monitored pore water pressure is compared with the numerical results, and it is concluded that the construction parameters can be changed in time to decrease the ground settlement.