Analysis On Deformation Of Existing Subway Tunnel Caused By Excavation Construction

In recent years, with the development of modernization construction in our country, many cities has been intensified efforts on the development and utilization of underground space. Because of this situation, a lot of foundation pit engineerings that located in downtown business district and housing concentration area had been appeared. This kind of excavation would not only invade itself security, but also cause unfavorable displacement deformation influence on nearby underground structures especially some large existing structures such as subway tunnel, even interferes with the subway tunnel operation.This paper analyzed tunnel deformation various factors to establish numerical calculation model by the using of MIDAS/GTS, and explore the structural displacement of the tunnel. Meanwhile, it has also researched on the excavation process below Automated People Mover systems (APM) influence with Haixinsha pit engineering as an example. The main contents are as follows:Firstly, this paper simulated the whole process of excavation, the simulation result showed that with the increase of excavation depth, the deformation of inferior tunnel is increasing constantly.Secondly, through the finite element simulation of tunnel at different depth location, the result showed that with the increase of vertical distance from pit bottom to tunnel vault,the deformation of inferior tunnel is decreasing .When the vertical distance from tunnel vault to den of foundation pit is less than ten meters, the relative changes of the buried depth distance would exert great influence on tunnel deformation of horizontal displacement.Thirdly, through the finite element simulation of tunnel at different side position,the result showed that with the increase of horizontal distance from pit bottom center to tunnel center, the deformation of inferior tunnel is decreasing. When the horizontal distance from tunnel center to den of foundation pit center is less than four meters, the different side position would exert great influence on tunnel deformation of horizontal displacement.Fourthly, this paper simulated the situation when subway tunnel is located in different soil including coarse sand, cohesive soil and silt clay, the result showed that when tunnel is located in adverse soil, its deformation would be exceed maximum allowable value(twenty millimeter) .Fifthly, this paper analyzed influence of excavation by basin opening way on below Automated People Mover systems with Haixinsha pit engineering as an example, the result showed that the deformation tendency is approximately same with model engineering's.