Analysis And Numerical Simulation On Ground Settlements Caused By Shield Driven Method Construction In Shenzhen Metro

Shield machine, with its safety, rapid, intelligent advantages, has been widely popularization and application in the construction process of urban subway. Engineering practice shows that shield tunnel construction inevitably cause ground surface settlement in the construction process, though its technology has developed very mature, the excessive settlement will directly affect the use of ground buildings and construction safety. How to reduce disturbance in the surrounding soils during construction, reduce influence of adjacent building and pipelines caused by construction as much as possible, and how to take measures to protect the influenced building, are the always concerned problems.Against the background of shield driven tunnel project from Honglang station to Xingdong station in Shenzhen metro Line 5, and based on the comprehensive analysis on the preciously existing achievements, by means of in-situ monitoring and numerical simulation this paper researched the ground surface settlement and stratum displacement laws caused by the excavation of using earth pressure balance (EPB) shield. At first, preliminary research on the mechanism of ground settlement was conducted, the general law of ground settlement was analysed on basis of field test data. Then, three dimensions finite element model of EPB shield-driven was established by MIDAS, the ground settlement curve caused by shield driven was obtained by calculations, and the characteristic of ground settlement was analysed. At last, combining with the parameters of actual construction, the some effective construction measures were put forward to control the ground surface settlement.The present study was mainly performed in several respects as follows:(1) The site monitoring measurement results of ground surface settlement in the earth pressure balance (EPB) shield construction was analysed;(2) According to analysis results of the on-site test data, and combining with actual stratigraphic characteristics, the influencing factors and occurrence causes of ground surface settlement caused by shield tunneling in Shenzhen area were analysed and researched, the general rule of ground surface settlement was concluded;(3) The primary theory of finite element method of tunnel excavation was described and numerical simulation of earth pressure balance (EPB) shield construction was carried out by finite element software "MIDAS" (GTS);(4) Combined with the parameters of actual construction, the some effective construction measures were put forward in order to control the ground surface settlement in earth pressure balance (EPB) shield construction.