Research On Settlement Control Of Newly-built Subways Underpassing Existing Track Stations

With the rapid development of urban underground traffic projects,there are more and more cases of new subway tunnels passing through existing rail station projects.In the underpass existing railroad station project,both the safety operation of the existing rail station and the safety and efficiency of the new subway tunnel must be ensured.However,due to the complexity of underground engineering,it is difficult to accurately calculate the influence of deformation of underground surrounding rock on the surrounding buildings,which makes it difficult for new subway tunnels to penetrate existing track projects.Based on this,this article relying on the construction of a new subway tunnel underneath the existing track line 3 station at the Chongqing North Railway Station,use the methods of theoretical analysis,numerical simulation,and on-site monitoring,the following aspects were studied in the construction of newly-built subways passing through existing railway stations:(1)The Midas GTS finite element analysis software was used to numerically simulate the construction of the new subway tunnels using the existing design CRD method and the benching tunneling method to be changed.The results show that the maximum settlement values of existing rail stations caused by the CRD method and the benching tunneling method were 0.85 mm and 1.95 mm.The CRD method was 44% of the benching tunneling method.The maximum horizontal displacement values of the existing railway stations caused by the CRD method and the benching tunneling method were 0.86 mm and 0.01mm;the maximum compressive stress of the existing rail station caused by the CRD method and the benching tunneling method excavation is 1.25 MPa and 1.61 MPa respectively;the CRD method is 78% of the benching tunneling method;the maximum tensile stress of the existing rail station caused by the CRD method and the benching tunneling method excavation is 0.40 MPa and 0.42 MPa respectively.The CRD method is 95% of the benching tunneling method.The maximum settlement caused by the CRD method and the benching tunneling method is 0.79 mm and 1.80 mm,respectively.The CRD method is 44% of the benching tunneling method.(2)The numerical simulation results show that the deformation of the existing rail station caused by the CRD method and the benching tunneling method is within the safety control range.Considering the construction schedule,manpower,economy and other factors,the new subway tunnel construction method was changed from the original CRD method to the up and down step method.(3)According to the results of numerical simulation,the corresponding risk control measures are put forward for the construction of the new subway tunnel relying on the benching tunneling method.(4)Remote static monitoring of the settlement and horizontal displacement of the station of existing track No.3 line with static level and inclinometer,real-time feedback monitoring data to guide the construction,and comparative analysis of the monitoring data and numerical simulation results,the deformation laws of the two have The consistency is very good,and the actual monitoring value of the maximum settlement of the existing railway station is 78% of the numerical simulation value,which confirms the accuracy of the numerical simulation and the effectiveness of the risk control measures,and further confirms the rationality of changing the CRD method into the benching tunneling method.