Impact Analysis Of Surface Subsidence Caused By Tunnel Construction Of Hefei Metro Line 2

Urban subway tunnel in the shield tunneling process,because of the uncertainty of the actual operation process,and in the process of construction inevitably cause disturbance destroy the soil,but also can produce the surface subsidence in the tunnel construction stage,local around the table when settlement is too large will directly affect the normal use of the ground buildings and underground facilities.In order to study in the shield construction in the process of how to reduce the disturbance of soil,we use the law of ground settlement caused by shield construction stage,to be able to predict in advance to the surface deformation,thus timely take effective control measures,the damage to reduce the disturbance of soil is feasible.In this paper,after reading related literature and on the basis of a large number of data of ground settlement caused by shield construction deformation law do a thorough research,through the shield construction process of the surface subsidence mechanism and influence factors of surface subsidence of surface subsidence rule of summary.Through the MAIDS/GTS software simulation under shield method in tunnel excavation process,in different shield advance under the factors such as pressure and different thickness of grouting layer,the surface subsidence induced by shield tunnel excavation in the process of the influence law were studied.In this paper the number two subway in hefei of shield tunneling construction for practical engineering background,according to the field of engineering geological conditions,selecting reasonable parameters for simulation,calculation and analysis in different stages of shield tunnel construction,shield tunneling of settlement of soil caused deformation,and the simulation results compared with the actual monitoring results and analysis:(1)the larger the shield tunneling pressure,the smaller the surface subsidence,but when the shield tunneling pressure is too high,the vertical displacement of the ground will mutate.(2)the thickness of synchronous grouting layer of shield structure can control the surface subsidence very well,and the larger the grouting thickness,the better the filling effect of tunnel shield generation construction gap.(3)through the comparison and analysis of the monitoring data,the shield tunneling pressure and the pressure of soil interbody should be controlled in a certain range,the soil can be elastic and plastic deformation,and the settlement quantity of soil is small.When the shield structure is excavated through a certain section,the lining grouting should be completed in time to achieve a new balance,so as to avoid the surface subsidence.(4)using the method of "MAIDS/GTS" software to simulate the tunneling process of tunneling under the shield method,the numerical comparison between the numerical simulation and the engineering monitoring is basically consistent with the results,indicating that the study has certain value.