| With the advancement of urbanization,urban congestion and traffic pressure have doubled,and urban subways,as a kind of green,environmentally friendly,strong carrying capacity,fast and convenient means of transportation,occupy more and more important positions,so all regions have begun to vigorously build Subway to relieve traffic pressure and city congestion.Because the shield method has little disturbance to the ground and high efficiency during the construction process,it is gradually widely used in the construction of urban subway tunnels.However,even with the advantage of small disturbances,the soil quality and hydrological conditions in different areas are different.During actual shield tunneling,disturbances to the soil layer will occur,destroying the original balance state of the soil,causing the adjacent buildings Uneven settlement and tilting.Therefore,it is necessary to strictly control all aspects of the process during shield tunneling to prevent uneven settlement and cause personal injury and economic loss.Therefore,it is very important to understand the scope of impact and the most unfavorable areas during construction,and make corresponding control measures to make the deformation value within a reasonable range and reduce unnecessary accidents.It also has research significance.This paper relies on the construction of shield tunnels between Fenglehe Station and Yulan Avenue Station of Metro Line 4 of Hefei City as the actual construction background,combined with the construction principle of shield method and the survey data collected on site,detailed analysis of Hefei subway shield Disturbance of surrounding soil layers and neighboring buildings during the tunnel construction process and the resulting mechanism.At the same time,using reasonable conditional assumptions and simplification of the model,the finite element analysis software Midas GTS NX was used to establish a dynamic shield machine excavation 3D model.According to the results of the model calculation,the influence of shield construction on the surrounding soil layer and adjacent buildings is analyzed according to the results of the lining of the sheet and the grouting behind the shield wall.The following conclusions are summarized:Impact on the surrounding soil layer: The ground surface settlement along the tunnel axis is obvious.Obviously,the settlement displacement is greater than the surface on both sides of the tunnel axis,and the closer to the building,the greater the settlement displacement.From the vertical distance from the top of the tunnel to the surface of the stratum,we can see that the upward displacement of the soil is smaller and smaller,indicating that the disturbance of the stratum soil is related to the distance.The smaller the soil settlement around the tunnel,the smaller the uplift at the bottom of the tunnel will be with the advancement of the tunnel.The uplift will gradually disappear after a certain distance.Impact on adjacent buildings: The impact of adjacent buildings due to soil disturbance is mainly horizontal deformation and vertical settlement.According to the calculation results of the model on the building,the wall settlement on the side of the building near the tunnel is the largest.As the shield excavation gets closer and closer to the building,the lateral settlement becomes larger and larger.When it is closest to the building,the settlement value is the largest,but the maximum settlement value is less than the building settlement standard limit,which is within the safe range Inside.Figure [17] Table [8] Reference [51]... |
