Stratum Deformation Analysis And Support Optimization For Construction Of Cang'an Road Subway Station In Qingdao

During the construction of the subway,surrounding rock and soil will be disturbed,which could lead to settlement deformation,causing the crack of the ground and pipe lines,as well as the sink of surrounding buildings foundation.It can lead to collapse in serious cases.It is necessary to properly monitor the formation deformation caused by subway construction process and take effective support mode to control deformation.This paper,based on Qingdao metro line 1 Cang'an road station,analyzed the numerical simulation results of field monitoring data and software FLAC3D.This paper studies the Surface subsidence law of shallow buried excavation station in Qingdao area and optimized the excavation support mode.The main contents are as follows:1.Combined with Qingdao metro line 1 Cang'an road station`s shallow tunnel excavation method,monitoring station excavation process of Surface subsidence,and analyzing the monitoring data,to study the law of Surface subsidence deformation during construction.The horizontal subsidence of the Surface is consistent with the normal distribution trend.The excavation of 1 and 2 excavation plays a leading role in the Surface settlement above the station,which accounts for about 82.94%of total settlement.2.According to the construction survey report of engineering geology and hydrological data,the project is simulated with software FLAC3D according to the concrete construction process.Comparing and analyzing the result with field monitoring data.It shows the numerical simulation results agree well with the field monitoring data,which state that software FLAC3D can simulate the excavation process of subway accurately.Furthermore,it proved that the excavation of hole 1 and 2 plays a leading role in the Surface settlement above the station.3.According to the numerical simulation results,the Surface subsidence curve is fitted with the Peck formula.We can get follow data:the width of the subsidence trough is 15.85m,the width parameter K of settlement tank is 0.69,the formation loss is 0.675 m~3/m,The formation loss rate is 1.7%.4.The excavation shall be combined and excavated at the left and right sides of the design stage to optimize the tunnel excavation.According to the numerical simulation results,the Surface settlement increment is small compared with that before optimization.The increment is merely 0.42mm.The simulation results of Surface subsidence in subsequent construction are still very small.And the final Surface settlement only increased by 0.2mm.it indicate the optimization method is feasible.5.Optimize the support mode of pipe shed.Through the numerical simulation analysis found that,in view of the engineering geological conditions,increasing the tube diameter and reducing pipe roof center spacing,can effectively reduce Surface subsidence.The reduction of the center spacing of the tube is more effective in reducing the arch and Surface deformation.In this project,the spacing of pipe sheds is 0.3m,and the pipe shed diameter is 159mm to optimize the simulation.The analysis shows that this optimization method can effectively control Surface subsidence and give consideration to economic rationality.