The Subway Shield Tunnel Construction Project Impact Analysis

With the rapid development of national economy in our country, the underground in many big cities are or will be built. In shield tunnel construction process, however, inevitably can produce disturbance on the surrounding soil mass and adjacent buildings, result in the crack of the adjacent existing buildings(elevation) and the surface subsidence. Therefore,impact analysis of tunnel engineering is very necessary, it can effectively reduce engineering accidents caused by the construction process, to ensure that the project is completed.This paper in view of the high range, you may encounter in the process of construction by shield method in risk, a project impact analysis and research, determine the shield tunnel construction risk points, then the risk point through the finite element software Midas GTS for the numerical simulation analysis, the main research contents are as follows:1 、 Object of the selected project from the assembling way of shield lining segments,segment assembling permissible error, the segment structure calculation theory and finite element simulation analysis for shield tunnel engineering risk research itself, to ensure that the lining ring meet the requirements of normal use and bearing capacity limit state.2 、 For the tunnel between districts, shield tunnel construction on the surrounding soil disturbance caused in the process of surface subsidence or uplift for engineering risk analysis,from the embedment depth(1.0 D, 1.5 D, 2.0 D and 3.0 D) and around the tunnel W/D(0.2,0.3, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.0, 1.2) value changes, in-depth study of shield tunnel construction in different working conditions cause the change rule of surface subsidence or uplift, find out the optimal interval under different buried depth and provide effective reference for later engineering value.3 、 Through finite element software Midas GTS three-dimensional numerical model is established, and simulation of shield method in the process of the construction on the surrounding soil and the influence law of adjacent buildings. In simulation unit of life change,shield tail different grouting pressure and thrust to achieve different constraints on dynamic construction simulation and control of shield tunneling factors impact on surface subsidence laws. Shield and focuses on the construction of neighboring different distance(L/D) the impact of architectural structures. The impact includes vertical and horizontal to the earth’s surface subsidence rule change rule, the settlement of building foundation, buildings and segment the mechanical characteristics and so on.Through the risk of tunnel, this paper research, to strengthen the prediction of risk factors in the process of subway construction, prevention and control, reduce the incidence of risk. At the same time for the new construction in the line of buried depth, around line interval and theprotection of the adjacent buildings has practical reference value.