The Simulation Of Subway Station Construction Using STS(Steel Tube Slab) Structure Combined With PBA Method

Shallow tunneling method is a mature and advanced new method in building subway station.However,in the process of building subway station especially in the condition of the super shallow-buried of large span,controling the ground surface settlement and stabilizing the whole structure of subway station are urgent to be solved.For the engineering background of the Shenyang metro line 9 Olympic center subway station was selected in this study.We utilized STS(Steel Tube Slab)structure combined with PBA method to construct the station.The method is to push large diameter steel pipe to specific land and to pour reinforced concrete in steel pipe and its conjunction area,which forms a pipe-roof as an advance supporting system.The STS method remedies the defeat of the super shallow-buried of large span station in great degree.Finite element software FLAC3D is used to simulate the process of constructing subway station with hydrogeology conditions of the related field engineering and data.In simulation research,different types of pilot tunnels,sequence of building,length of step,length of drawing pace,which shows different results of various degree of ground surface settlement and stability of building were tested.The whole process of building to study the change law of ground surface settlement and force condition of pipe-roof are simulated.The results show that considering the situation of field construction and safety,we choose to dig pilot tunnel from the bottom up with length of pilot tunnel step from 2D/3 to 4D/3 and adopt short drawing pace of construction,which can effectively retard ground surface settlement,stratum displacement and stability of excavation face.Besides,it is suitable for construction and the shortest loss rate of formation among other scheme was obtains.According to the simulation of whole construction of station,we obtained that the change law of ground surface settlement during the construction by utilizing STS(Steel Tube Slab)structure with PBA method and the forced condition of pipe-roof,which provides a useful reference in building subway station.