Research On Seepage Stability Of Fractured Rock Mass Tunnel Under Limited Discharge Of Groundwater

The surrounding rock and groundwater in the fractured rock mass are in a relatively balanced state.After the tunnel is excavated,the tunnel itself forms a new drainage channel,and a large amount of groundwater gushes out.The original seepage balance state is broken,thus forming a surge water disaster.Water inrush disasters pose serious threats and challenges to the safety of construction personnel and the balance of the ecological environment around the tunnel.Therefore,for the requirements of safety,economy and environmental protection,we need to establish a set of The groundwater discharge standard of the ecological environment protection tunnel,and on this basis,the seepage stability of the fractured rock mass is studied,in order to achieve better prevention and treatment of the inrush water disaster of the tunnel.On the basis of summarizing and summarizing the research achievements of scholars at home and abroad,this paper uses theoretical derivation,numerical simulation,experimental analysis and a combination of engineering practice,taking Fushui Mountain Tunnel as the object,and limiting the discharge of groundwater based on ecological environmental protection.The formulation of standards,the seepage characteristics of fractured rock mass,the coupling mechanism of seepage field and stress field,the influencing factors of the seepage stability of fractured rock tunnel,the grouting simulation of water blocking and drainage have been carried out in-depth and specific research,the main work and research The results are as follows:(1)The technical application of the limited discharge of groundwater in tunnel projects at home and abroad has been studied.Based on the requirements of ecological environmental protection,combined with the actual situation of the project,through theoretical calculations,different seasons,different rock permeability coefficients,different water level heights and different drainage volumes have been formulated.Tunnel groundwater discharge standards.(2)Through the permeability test of the fractured rock mass test block,the variation law between the permeability coefficient and the confining pressure,pore water pressure and strain of the fractured rock mass is analyzed;at the same time,by infiltrating the fractured rock mass test block Numerical simulation study to verify the rationality and correctness of the test results.(3)To study the coupling between the stress field of the fractured rock mass and the groundwater seepage field,based on the discrete element method,compare and analyze the changes of the surrounding rock stress field and the groundwater seepage field after the tunnel is excavated under the coupling calculation and the non-coupling calculation.The results prove that the coupling calculation is more reasonable,so it is necessary to consider the coupling effect.(4)On the basis of considering the fluid-solid coupling effect,through the method of controlling a single variable,the factors such as joint inclination angle,joint spacing,joint normal stiffness,vertical in-situ stress and tunnel water level height,etc.are studied on the seepage stability of the fractured rock tunnel The law of influence provides reference for tunnel excavation of fractured rock mass under different working conditions.(5)Using the Bingham fluid model for grouting simulation,taking the engineering example as the background,under the standard of limited discharge,through the simulation analysis of the working conditions of different grouting ring permeability coefficients and grouting ring thickness,it is determined to consider the rock mass seepage And the optimal value of grouting parameters under the conditions of surrounding rock stability.