The Study On The Micro-structure And Dynamic Characteristic Of Soft Clay Around Tunnel Under The Subway-Included Loading

For recent years big cities, in order to solve the traffic crowd problem, are fairly enthusiastic about subway-tunnel-building, which arouses many environmental problems, especially the subsidence and deformation of soft clay layer around the tunnels of the running subways. These environmental and geological problems have raised the attention of the government and technicians. The monitoring of subway tunnels and the environment around shows that there is subsidence and deformation of soft clay layer in Shanghai. The subsidence at one section of Line one has exceeded 25cm, which results in the cracks on the shells of tunnels, penetration of water and leakage of mud. And that poses a great threat to the normal running of the subway. The subsidence, due to the deformation of tunnel, has also brought out the groundwork deformation and upside-structure split of the buildings nearby. On the basis of that, this dissertation discusses microstructures of soft clay around the subway tunnels and its dynamic responses under vibrating pressure of subway train, focusing on the problems of subsidence and deformation of soft clay layer around the tunnels. On the basis of that, this dissertation discusses microstructures of soft clay around the subway tunnels and its dynamic responses under vibrating pressure of subway train, focusing on the problems of subsidence and deformation of soft clay layer around the tunnels. Based on the results of in-situ drill monitoring, laboratory GDS (Global Digital System) test SEM (Scanning Electric Microscope) test and MIP (Mercury Intrusion Porosimetry) test, the dynamic responses of saturated soft clay and its microstructure varieties are qualitatively and quantitatively analyzed, and the deformation of micro and macro structure is then coupling analyzed. Three-dimensional finite element model of soil's dynamic response in the course of subway train passing is built on the base of existing transitional dynamic finite element method. The results are as following:1. There are two response frequencies of the saturated soft clay around the tunnel when subway rolls by. The higher is between 2.4 Hz and 2.6 Hz, and the lower...