Three-dimensional Numerical Analysis Of Metro Station Construction By Large Diameter Shield Tunneling Combined With PBA Method

In the construction of underground railway of Beijing urban, the shield tunnel machine is widely used because of its high construction speed, high quality, safety and stable, low impact on the surrounding environment. However, this method is limited to interzone tunnel, the different construction methods between interzone tunnel and station is a serious problem, which has not been solved until now, the contradiction between interzone construction and station construction is more and more serious. A construction method that to use shallow mining method enlarge subway station on the basis of large diameter shield tunnel can be regarded as a new idea.Taking the Gaojiayuan station of Beijing metro line14as an engineering background, use pile-beam-arch (PBA) method to enlarge a large-size shield tunnel on the basis of10miles is introduced. Three-dimensional finite element model is used to simulate the metro station construction on the basis of soil-structure interaction theory. The mechanical characteristics of the segment, the beam-wall, the primary linning, the temporary strurts are respectively researched, simultaneously, the deformation law of the soil during enlarging construction is studied.The results shows that the structural force transferred frequently during enlarge metro station. The K-segment which is very important to the safety of the metro station bear a complicated force. Detail design of the K-segment need to conduct in the future.