Study On The Effects Of The Surrounding Environment Caused By The Subway Excavation

With the development of underground engineering in China,tunnel engineering is growing more and more in the city,the impact of underground engineering on the surface environment is also growing.Therefore,a systematic study of underground tunnel excavation on ground settlement is very essential.A combination of numerical simulation and field monitoring based on the background of Harbin subway is studied in this paper in order to obtain the surrounding environmental effects caused by the subway excavation.Based on the finite element numerical software Midas / GTS,the three-dimensional model of the subway tunnel is established.The key parameters of the three constructions are analyzed,and the different parameters are studied in detail.The effect of deformation on the deformation of the surrounding strata.The influence of the sensitive parameters such as the horizontal spacing of different tunnels and buildings,the foundation depth of the building,the parameters of the soil layer on the deformation of the existing buildings,the total settlement and the difference settlement of the foundation are summarized.The vertical and horizontal settlement of the surface and the horizontal convergence are compared with the finite element,and adjust the parameters,the establishment of the corresponding forecasting model.The following conclusions are obtained: The greater the tunnel depth is,the greater the deformation of the soil caused by the excavation of the double tunnel is;the internal force of the tunnel lining structure increases with the increase of the buried depth;the tunnel excavation step length has an optimal value: Excavation is beneficial to reduce the surface subsidence value.The depth of the foundation of the building is inversely proportional to the settlement of the building.When the foundation depth of the building exceeds the bottom of the tunnel excavation area,the effect of changing the foundation depth on the deformation of the building is very small.The greater the elastic modulus of soil gets,the smaller the surface subsidence is.Dark excavation method is not applicable to the poor soil conditions.If the conditions are only allowed to use dark excavation construction,for the weak formation of small and medium sections can be considered using CD,CRD method or large tube method,should not use the full section method.