The Impact Of Tunnel Construction To Surface Structures In Completely Decomposed Granite Area

With the rapid development of China's economy, China's railway construction is confronted with unprecedented opportunities, however at the same time is faced with limitless new challenges. Since China is a multi-mountain and multi-hilly country, it is inevitable to go through some mountain areas in railway construction. Tunnel have some Incomparable advantages while pass through those mountain areas. Notwithstanding with the railway grade constant increasing and sometimes in order to improve the speed and ameliorate the linear, sometimes the tunnel is inevitable to go through some surface conditions complicated,joint and cleavage development,water-rich areas and so on. In this case if inappropriate construction measures were taken, the surface structure will easily damage even collapse. Therefore, it is urgent for us to research the impact, caused by tunnels construction, in soft rock region.This article mainly study object were the Sangpushan tunnel which lie in the passenger dedicated lines of Xiamen-Shenzhen segment XSGZQ-5 and the high-voltage tower which located at the top of the tunnel. The finite difference FLAC3D software was taken to established calculation model and the tunnel three-stage seven-step excavation process in decomposed granite areas was simulated. At the same time the surface settlement laws on the granite area have been summarized and the tower monitor were guided by that information. During the tunnel excavation, automatic monitoring equipment was used to monitor the foundation settlement of the iron tower. At the same time metabolism GM (1,1) model of the Grey System Theory was used to forecast the foundation settlement. At the end, according to the numerical analysis results and the measured settlement, the security of the high-voltage tower during the tunnel construction was given.