| Shield tunneling is a vital method in subway construction in soft stratum.It has many advantages compared with other methods, however,it still has disturbing effects on the soil and buildings nearby the tunnel during the construction course inevitably.The mechanism of turbulence of soil around tunneling line has been interpreted, the genetic analysis of the turbulence has also been made and the reasons which cause the stress/strain turbulence and the ground settlement have been analyzed comprehensively in this paper.The Finite Element Method is an effective tool for studying the ground deformation by shield excavation,the predecessors′research on this subject is reviewed and generalized and the settlement of tunnel excavation is deduced in theory.The research is based on the available documentary of the line 1 of the Tianjin Metro Project. A 3D nonlinear constitutive model taking into account those main components such as the nonlinearity of soil material, grouting pressure, face pressure,the structure void of shield and the interaction between the gasket,shield and soil is put forward by means of general FEM program ANSYS to simulate the advance of a tunneling shield. The deformation laws of soil around the tunnel are given and the results of numerical analysis are compared with the measured soil displacements at site.The problems caused by adjacent construction of shield tunnel are discussed.On the basis of the 3D excavating model,taking a frame structure office building for example,another model regarding the building and its foundation with cavern as a whole and considering the tunnel-soil-structure interaction is brought forward. Its differential settlement and variation of internal force as a result of the advance of a tunneling shield is investigated and the safety of the building is evaluated when a shield tunnel passes through the building .Several meaningful conclusions are obtained.
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