Numerical simulation to determine the critical safe thickness of water-resisting rock wall based on FLAC3D

Caverns with high pressurized water ahead of tunnel face tend to cause water inrush. So, the determination of the critical safe thickness of the water-resisting rock wall to prevent water inrush geohazard is of great significance during karst tunnel construction. Firstly, to obtain the critical safety thickness of rock wall ahead of karst tunnel face, a numerical model based on FALAC3D and the method to determine the critical safe thickness are established. Then, a series of numerical tests planed by the orthogonal testing theory have been carried out. The rock mass level of rock wall, dip angle of strata, lateral pressure coefficient, cavity scale, water pressure and buried depth of tunnel on the critical safe thickness is studied. Finally, the regressive formula to determine the critical safe thickness of the water-resisting rock wall is established by means of numerical testing results. Taking for examples the Maluqing tunnel on Yiwan railway, the reliability and rationality of the proposed methods were proved, so providing reference for similar engineering projects.