Study On Surface Subsidence Of Subway Station And Its Influence On Adjacent Pipelines By PBA Method

The construction of subway stations by the PBA method has been used in many subway projects,but the settlement caused by the construction poses a threat to the safe operation of the surrounding buildings and pipelines.This paper takes Wanshou Temple Station of Beijing metro line 16 as the engineering background.Using Sufer and Origin data processing software and Midas-GTS geotechnical engineering numerical analysis software,The ground settlement,station structure,soil displacement in adjacent area and the pipeline in the affected area caused by the station are analyzed.The main conclusions are as follows:1.In the whole construction process,the larger settlement stage is the excavation stage of the pilot tunnel and the construction stage of the buckle arch.The amount of settlement generated by the construction steps,such as the excavation of the first,second and third layers of the main body of the station,and the construction steps of the side wall two and the floor,also accounts for a considerable proportion of the settlement.The horizontal displacement of the upper part of the station is basically symmetrical.With the construction of the station,the maximum displacement of the horizontal displacement approaches the axis of the station.2.The surface subsidence produced by the PBA station of the Wanshou temple is relatively regular,which is basically consistent with the scope of the main body of the station,and the maximum settlement occurs at the middle axis.The settlement near the cross channel is relatively large.By fitting and analyzing the curves of four settlement sections on the upper part of the main body of the station,the empirical parameter k of the width coefficient of the sink is in accordance with the results of the previous scholars.3.The difference of the settlement value before and after the excavation of the guide tunnel is the largest and the most rapid change,which indicates that the influence degree of the tunnel excavation on the uneven deformation of the pipeline is the greatest during the whole process of the station excavation.From the analysis of the displacement of the gas pipeline,it can be seen that the vertical displacement of the actual monitoring points on the surface is less than the displacement of the pipeline in the formation,and the difference between the two is increasing with the construction.