ALLOWABLE GROUND SUBSIDENCE BY CONSTRUCTION OF THE CHONGWENMEN STATION AND ITS SIMULATION WITH THREE-DIMENSIONAL FINITE ELEMENT METHOD

The Chongwenmen station of Beijing metro line No.5 goes beneath the existing subway line No.1.In order to guarantee the normal operation of the existing metro line and the safety of underground construction,the stratum displacement caused by construction must be well controlled.This paper presents the analysis of allowable ground subsidence during construction the Chongwenmen station project.In order to control the ground subsidence and guarantee the safety of construction,big pipe umbrella of small rigidity or pipejacking of greater rigidity is used as pre-support.In this paper,three-dimensional finite element software,3D-Sigma,is used to simulate effects of the construction and estimate the subsidence of the interval tunnel caused by the construction.At the end,effects of big pipe umbrella and pipejacking pre-support are analyzed and compared,which can provide guidelines for selection of appropriate presupport scheme.