| Tunnel construction technology with shield driven method is being more and more developed and applied in building Metro engineering because of its' unique characteristics and advantages such as intelligence, safety and quickness, etc. The shield driving method has been one of the main construction methods in the metro engineering of our country. Though shield driven method has obtained splendid achievements, it is inevitably caused ground surface settlement. This will affect the normal use and the safe running of the shield tunnel and the ground surface building while the ground surface settlement is too much.The surface settlements and influence on surrounding environment caused by shield tunnelling are the problems highly concerned in the design and construction process of shield tunnel.The finite element method is the main method of tunnel excavating. In this paper, three-dimensional Finite Element Method is applied to study the ground deformation by shield driven. According to the real engineering, the author bring forward a 3D model to simulate the tunnel excavating by means of the finite element method. The key factors such as the soil conditions of Tianjin area, the nonlinearity of soil material and the structure void of shield and the interaction between the gasket and soil also been taken into account in this 3D model.Based on a subway project in Tianjin, three-dimensional finite element analysis is carried out to simulate double-tube parallel tunnels with short distance between them. In this paper ABAQUS is used to analyze several projects. The laws of influence on the old tunnel and ground face settlement caused by the construction of the new tunnel are obtained. The results show that the modulus of soil and the net distance between the tunnels and the grouting pressure have great influence on the interaction. The softer the soil is, the more severe the influence is, which should be considered in projects. |
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