Research On The Stability Of Shield Segment For Metro Station Constructed By Enlarging Shield Tunnel

In recent years, shield method and shallow underground excavation method are widely used in tunnel construction and metro station construction respectively in china. Accordingly, the construction contradiction between metro stations and running tunnels become more evidences, including inconsistent construction speed and mutual interference, which could weaken the advantage of shield method and increase the project cost. Based on the comprehensive technical research project of expanding-building station combining shield method and current condition of Beijing metro station construction, the displacement and stress of shield segment are analyzed in this paper.First, the theory history and common theory of shield segment design are summarized in the paper. Then, according to the construction scheme of the CRD-dug excavation extended Tower-style subway station, adopting domestic 6m diameter reinforced concrete segment, the construction scheme is simulated with three-dimension numerical method, by using the shell-spring-contact calculation model of stratum-structure mode. The pre-stress is simulated by decreasing temperature method with coupling independent model method. The segment joint effects are the main consideration in analysis, especially analyzed three-dimensional internal force of segment and pre-stress impacts on segment stress. Through the analysis of the construction process, treatment method of key parts is proposed. And these conclusions can apply the theory basis to design and construction.