Analysis On The Stability Of Existing Stations Under Tunnels

With the continuous increase of urban population in China,traffic congestion phenomenon is becoming more and more serious,in order to meet people’s growing travel needs,ease the traffic pressure is also urgent,so the major cities began to develop urban rail transit.More and more dense new lines inevitably overlap with existing lines,in order not to affect the daily operation of existing lines,it is necessary to choose a reasonable excavation mode and support method for the new tunnel.In this thesis,the mechanism of surface subsidence caused by excavation of lower tunnel is analyzed,the law of formation subsidence is summarized,and the characteristics of each stage of formation subsidence,the interaction relationship between vertical displacement of formation and overall settlement are expounded.Taking the subway line of a city as the background,this thesis summarizes the risk factors for the stability of the station in the excavation of the tunnel under a subway station in the city,and analyzes the effect and effect of various reinforcement measures on the construction of the tunnel.On the basis of collecting a large amount of data,this thesis analyzes the station settlement caused by excavation by using stochastic medium theory,numerical simulation and similar engineering analogy,and analyzes the surface subsidence caused by different excavation modes and different excavation positions in the tunnel,as well as the influence on the existing stations.The results show that the construction of the tunnel under the subway station needs to be pre-grouting,and the influence produced by the step method is the least,and according to the monitoring data,the settlement of the axis in the tunnel is the largest.Check the land subsidence produced by other stations of the subway line during construction,verify the rationality and error of the numerical simulation,and the results show that the settlement size meets the excavation requirements of the subway station.