The Study On The Micro-structure Distortion Mechanics Of Soft Clay Under The Subway-Included Loading

Aiming at solve the environment problem of the asymmetric settlement of soft clay embankment of the railway tunnel, the paper starts from testing on site, then adopts GDS (Global Digital System) which is the quit advanced triaxial apparatus in the world to carry out a large number of laboratory tests, and finally, SEM (Scanning Electric Microscope) and MIP (Mercury Intrusion Porosimetry) measurements are taken. The results are as following:1. There are two response frequencies of the saturated soft clay around the tunnel when subway rolls by. One is between 2.4 Hz and 2.6 Hz, the other is between 0.4 Hz and 0.6 Hz.2. From the laboratory analysis, the pore pressure curves can be divided into three distinct stages, and a pore pressure model is presented in this paper, which is aiming at demonstrating the increasing rules of saturated soft clay under the subway-included loading in Shanghai Area.3. The axial strain does not increase immediately when the loading is loaded, yet the rebound occurs, which is much resembled with the shearing expansion of sand. Moreover, the distortion of the mass body located in the side place of the tunnel is relatively small, but the mass body lies at the bottom of the tunnel produces larger axial distortion.4. Flocculation and honeycomb-flocculation are the mainly structure in the 4th layer in Shanghai Area, and most of the structure elements are laminar, which gives birth to the overhead structure with high porosity.5. There is a trend of compression during the vibration, but it may bring more overhead structure more easily. When CSR is increasing, with the vibration goes continuously, the former structure element with compression trend will slip and faulted between the less-firm elements.6. There is mainly macro pore in the in-place saturated soft clay in Shanghai Area, and the ink-bottle effect exists in the intrusion stage in the MIP test.7. With the obtained analysis results, we can draw the conclusion that the settlement of the subway embankment will continues for a quit long time.8. The micro-testing results imply that the Bock Model is not suitable for the saturated soft clay in the super-low stress condition.In the finality, the problems requiring further studies are discussed.