Numerical Simulation Of Fluid-Solid Coupling Effect In Surrounding Rock In Rich Water Tunnel

In order to analyze the stability of the arched tunnel after excavation in rich water rock, based on fluid-structure interaction theory, the simulation of fluid-structure interaction effect was came true by use of FISH language and equivalent continuous media seepage model in FLAC-3D. The distributions of seepage field and flow vector are elaborated, and a comparison of plastic zone, stress field and deformation of surrounding rock between consider fluid-solid coupling and out of considering fluid-solid coupling is made. By considering fluid-solid coupling, the influences of excavation steps, excavation procedure and the shape of tunnel section on pore pressure, displacements and water inflow are analyzed. Result show that comparing with out of considering fluid-solid coupling, the range of plastic zone and the length of shear bands are bigger, and the total vertical stress σzz reduces 10% relatively in considering fluid-solid coupling. There is a reinforced area in surrounding rock, flow vector is intensive and larger in tunnel arch springing. With the increase of excavation steps, pore pressure and vertical displacement in tunnel vault decrease obviously, and water inflow is increase. Bench cut method is better than full face driving based on pore pressure, vertical displacement and water inflow. Different shape of tunnel section let different seepage field and flow vector, so we should choice the shape of tunnel section according to different geological conditions.