Sensitivity Analysis On Influencing Factor Of Seepage Field In Mountain Tunnel Of High Pressure And Rich Water Zone

Because of the huge mountain area of our country,the topographic condition is more complex,so in the mountain tunnel construction under complex conditions,there are often encounter abundant water areas,high pressure and rich water problems will come.In the tunnel excavation process,how to calculate the water pressure of the lining structure and water inflow of the tunnel section,as well as the safety of lining structure under water pressure load are very important research contents of tunnel seepage field.According to the data,there are many researches on the single factor of tunnel seepage field,while few comprehensive study on the influence of various factors on the seepage field.Based on the concept of equivalent lining,the paper studies on six kinds of influencing factors of seepage field with orthogonal test theory and effective interval of the most significant factors.Main research results and conclusions are as follows:(1)Establish calculation model with principle of equivalent lining,comparing the mean pressure of composite lining under water blocking and discharging structure and principle of equivalent lining.Through trial calculation,the reasonable equivalent lining permeability coefficient is obtained.(2)Compare the lining water pressure and tunnel water inflow of equivalent lining,"water shutoff and limit discharge" composite lining and axisymmetric solution,the result is that water pressure and water inflow of the composite lining can be calculated by the equivalent lining method,and the equivalent lining method is feasible in theory.(3)Based on axisymmetric solution,the influence factors of tunnel seepage field are equivalent lining permeability coefficient,equivalent lining thickness,preliminary bracing permeability coefficient,preliminary bracing thickness,grouting circle permeability coefficient,grouting circle thickness.Study on equivalent lining external water pressure,tunnel water inflow and equivalent lining structure safety with orthogonal test combining equivalent lining method,the result is that the equivalent lining permeability coefficient(drainage capacity)is the most significant factor affecting the seepage field.(4)In the tunnel seepage field,the equivalent lining water pressure and tunnel seepage flow are not linearly increased with the increase of the equivalent lining permeability coefficient,while there is a certain effective influence interval.The effective influence interval of equivalent lining permeability coefficient in Huayingshan tunnel is 1.04×10-7cm/s-2.04×10-6cm/s.