The Study Of Failure Mode And Evolution Mechanism Of Water Filling Cavity Water Inrush

The tunnel construction is difficult in karst region because of the complex geological condition and many geological hazards including water and mud inrush threat to the safety of the tunnel construction.Based on Xie Ma tunnel engineering,we will study the failure mode and the mechanism of water inrush that induced by tunnel construction through the indoor test,model test and numerical simulation.The main contents are following:(1)Cavity water inrush test system is developed and this system has many advantages like multi-type and visual characteristics and so on.Otherwise,the test cycle is short and it is convenient and concise for the test that aims to study the macro law.The test of cavity water inrush is conducted to simulate the water inrush process and then summarizes the mode of rock mass failure.At last,we analyze the hole water inrush process that including fracture produce,evolution,the water inrush channel formation and water inrush.(2)The new hydra-mechanical model test system is developed and the system is composed of test box,in-situ stress loading system,hydraulic loading system,control system,information monitoring system and video monitoring system.This system has many advantages like high bearing capacity,high visualization,high automation.Taking limestone sample from Xie Ma tunnel and study the mechanical properties of limestone that in karst area through uniaxial compression test,the Brazilian splitting test and the triaxial compression test.The model test of cavity water inrush is conducted to analyze the influence of cavity that full of water on the stability of rock mass and the variation of physical fields during water inrush.At last,we will reveal the mechanism of cavity water inrush through above information.(3)A three dimensional model is established by FLAC3D to simulate the tunnel excavation that has high water pressure cavity in front of tunnel face.Then we analyze the variation of displacement,stress and seepage field during tunnel excavation to study the influence of high pressure cavity on the stability of rock mass.