Study On The Mechanical Performance Of The Subway Station With Large Size Of Holes In The Floor

With rapid development of the economy and sharp increase of city population in China, it has triggered many severe problems such as heavy urban traffic and air pollution. So the construction of subway station is booming in many cities. Large size of holes in the floor of subway station is usually required for the construction of track skeleton during the construction stage. Earth pressure exist tremendous influence on the subway station with track panel well when independent supporting structure cannot be adopted under the limitation of surroundings. There are obvious difference in design calculation between the large size of holes portion and other portion in subway station. However, the variation law of stress has not yet been figured out for the large size of holes portion in the subway station when both piles and station structure bear earth pressure together. It is necessary to analyze the mechanical performance of the subway station with large size of holes in the floor under the influence of different structural measures.Based on the engineering background of one subway station in Chengdu, a three dimensional finite element model considering the interactions between the soil and structures is setup to simulate the construction procedures of the subway station with track panel well using MIDAS/GTS software. The Mohr Coulomb constitutive model is used to present the behavior of the soil. The interaction between the soil and the diaphragm wall is simulated by Goodman contact element. The effects of pile stiffness, overloads, soil property and longitudinal beam section size on mechanical performance and deformation of the subway station with track panel well are investigated in details.The large size of longitudinal beam has hindered track panel well's arrangement in the original scheme. In order to reduce the size of longitudinal beam, further strengthening measures including additional counterfort columns and different forms of double row piles are performed by 3 D finite element analyses of soil structure model to investigate the effects on stress laws of station structures with track panel well. The bending moment in the controlled section calculated by stress integration is also discussed.In terms of high complexity and large amount of computation in soil structure model, two load structure simplified models of the subway station with track panel well are setup by SAP2000 software, the differences between soil structure model and load structure model are analyzed. The simplified models will provide reference for the design of the subway station with track panel well.