Ground Settlement Measurement and Numerical Simulation Analysis of Vertical Shaft Machine

The vertical shaft machine (VSM) construction method is a new submerged shaft excavation construction method in which the manipulator is used to excavate saturation stratum and assemble the prefabricated segments at the same time.This paper takes Shanghai Zhuyuan Bailonggang Sewage Connecting Pipe Project as engineering background,comprehensively compares and analyzes the theoretical calculation,field measurement results and numerical simulation results,so as to systematically analyze the first engineering case of VSM in Shanghai soft clay area.The field measurement shows that the maximum ground surface settlement is 15.2mm,the maximum horizontal displacement is 3.74mm,and the influence range on surface settlement is about 30m.Compared with the excavation construction under the traditional diaphragm wall,VSM has strong applicability to soft clay layer in Shanghai.Using the finite element analysis method,the numerical simulation of VSM construction method for the settlement and deformation,earth pressure,shaft instability and inrush risk are carried out.And the difference along with numerical simulation results,the theoretical calculation and field measurement results of VSM is discussed.Results show that the numerical calculation using fluid-solid coupling,elastoplastic model,Mohr-Coulomb criterion and Biot consolidation model can effectively simulate the construction of VSM.And the safety factor of shaft stability is greater than 1.8,so that the risk of soil instability and bottom hole inrush is very small.Finally,the countermeasures and suggestions for deformation control in the future are put forward.