Numerical Simulation Of Interaction Between Stratum And Subway Tunnel Under The Environment Of Active Ground Fissures

Ground fissure, as the typical geological disaster of Xi'an, has causeed serious trouble to the construction of the city , especially has a greater impact on the construction and safe operation of the subway line 1 and line 2 under construction in Xi'an. We used to focus on the causes mechanism and activity patterns of xi'an ground fissure and so on,however, the study on the interaction between stratum and construction is less. Therefore , to make deeper study on this problem will make the combination of of research results on ground fissure with project construction more closer , and can provide theoretical and technical support for the subway tunnels design of other lines on disaster prevention across the ground fissure .In this paper ,ground fissure in Xi'an was the background of geological disaster , and the subway line 1 and line 2 under construction in Xi'an was chosed as the study subject .On the basis of existing research data the possible deformation and destruction pattern caused by ground fissure was analyzed , and the model of interaction between stratum and subway tunnel was built; On the assumption that the ground fissure did not exist, the internal force of sectional horseshoe tunnel was analyzed with the load-structural method, the mechanics response of tunnels across ground fissure at a different angles from 90°to 30°was analogied , the variation regularity of deformation and stress of tunnel and soil around was obtained.The results showed that there were vertical dislocation between segments of tunnels, the distance of dislocation was at the most at the ground fissure , the horizontal dislocation between segments of tunnels also arised at the same time and it was larger when the tunnel across ground fissure was at a smaller angle, as a result water prevention should be strengthened.By comparing the results of numerical simulation with internal force with the method of structural -load, the impact of the activity of ground fissure to subway tunnels was discussed.Through comparative analysis in detail, it can be known that the damage was the most serious when the tunnel crossed ground fissure at 50°, and the surrounding soil was influenced most severely. The condition of vertical intersecting was profitable for the subway tunnel and had less influence on surrounding soil.