An efficient method for evaluating the ground surface settlement of Hangzhou metro deep basement considering the excavation process

Based on the 16 collected well-documented excavation cases of the Hangzhou metro basement, the standard parameters of the basement, the standard excavation process, and the standard soil layer are established. With the above parameters, a standard three-dimensional finite element model about Hangzhou metro basement excavation by PLAXIS 3D software is subsequently established. The small strain hardening constitutive model considering the characteristics of small strain of soil and unloading of excavation is adopted for the numerical analysis of basement excavation. By comparing the ground surface settlement (GSS) given by the numerical model with the field measurement results and the published empirical solution, the validity of the established numerical model was checked. The characteristics of GSS were further analyzed. The results indicated that as the excavated depth exceeded 7 m, the distribution of transverse GSS changes from cantilever to ″three segment broken line.″ The longitudinal GSS is largely affected by the corner effect and the excavation depth. Subsequently, an innovative simplified method considering the excavation process was presented to calculate both the transverse and longitudinal GSS outside excavation. The research results could provide a new approach to reasonably predict the GSS caused by basement excavation.