Stability Analysis Of Surrounding Rock In Mountain Tunnel With Water Rich Fractured Zone

China is a mountainous country.In the construction of the national traffic network,the tunnel with the function of crossing the mountain is an indispensable part.In the course of the excavation of the mountain tunnel,the well developed fault fracture zone and groundwater are often encountered.The state of the rock mass in the fault zone is mostly fragmentary.When the tunnel is excavated,it is produced here.The two redistribution of stress in rock mass,coupled with the interaction of groundwater,brings many difficulties to tunnel excavation,which often causes bad geological phenomena such as tunnel collapse,water gushing and mud gush.Based on the engineering background of the No.1 Tunnel of Xiao Bei Shan,Guangdong Province,the stability analysis of the surrounding rock in the water rich fractured zone of the mountain tunnel is carried out by the method of theoretical analysis,field monitoring and numerical simulation.The seepage flow and fluid solid coupling theory of rock mass are used to study the seepage form of groundwater and three commonly used hydraulic coupling models.The coupling of the seepage field and the stress field in the stratum is theoretically analyzed.The three-dimensional numerical analysis model of the No.1 Tunnel in the small Beishan Mountain is established by using the FLAC3 D analysis software,and the coupling of the seepage field to the stress field is combined.The effect of the initial support of different grades of surrounding rock and the influence of different excavation methods,different grouting conditions and fracture zones on the stability of surrounding rock are analyzed.Based on the data obtained from the construction site monitoring data and the data extracted from the numerical simulation,the pore water pressure field,stress field,displacement field and data curve are compared and analyzed.The distribution of the seepage field under different conditions and the influence of the surrounding rock are studied.The monitoring data and the simulation number are compared,and the monitoring results and the numerical values are analyzed.The difference between the results of the simulation.The research results show that the initial support effect is closely related to the surrounding rock grade,and the lower the surrounding rock grade,the more significant the initial support effect is.The method of tunnel excavation affects the distribution of pore water pressure field and the process of stress and displacement.The advance grouting has a good effect on water resistance and seepage prevention,which has obvious influence on the pore water pressure field near the tunnel.The smaller the permeability coefficient,the greater the thickness,the stronger the water resistance,the better the effect.In the tunnel excavation,the relevant factors should be taken into consideration,and the appropriate grouting parameters should be selected.The dip angle of fracture zone plays a guiding role in the movement of groundwater and affects the stress and displacement distribution of surrounding rock around the tunnel.The above conclusions are of some reference value to the actual construction arrangement of the mountain tunnel through the water rich fractured zone.