| The geology of Karst area is complex and changeable and there are many uncertainties.The dissolution in the karst area to the soluble rock adversely affects the geology.The construction of tunnel in karst area changed the existing groundwater balance,and the existence of Karst cave could make the water pressure concentrated in the tunnel lining the effect of stress concentration,resulting in the tunnel emergence of water gushing mud,lining off,and other phenomena,serious threat to the normal operation and safety of the tunnel.Based on the indoor tunnel model test,the paper takes the highway tunnel in the karst area of Guangdong province as the project.This paper studies the stress characteristics of the lining of the karst area running highway tunnels in different karst cave,different inclination angle of the surrounding rock,different rainfall intensities and loading conditions,and analyses the monitoring data of the tunnel lining surface strain,pore pressure,soil pressure and surrounding rock displacement of lining.Mainly obtains the following conclusions:1.In this experiment,the two kinds of karst cave distribution states(along the horizontal plane and vertical face of the tunnel lining center position are arranged and the symmetrical arrangement along the tunnel lining center position toward 45 ° and135 ° plane)has great difference in the safety effect of tunnel lining.In general,the former is safer;2.The diameter of karst cave has the least influence on the characteristics of tunnel lining,and its function is mainly embodied by combining the inclination of the surrounding rock joints and the distance between Karst cave and tunnel.3.The distance between Karst cave and tunnel.has a significant direct impact on the safety of tunnel lining,with the distance from 1 time times the diameter of the tunnel increase,the tunnel lining safety performance as the first reinforced after the weakening,at about 1.5 times the distance of the tunnel diameter,the tunnel lining is the worst security;4.The inclination of the surrounding rock joints has a complicated influence on the safety of tunnel lining,mainly manifested as the effect of the additional stress and the pore pressure regulating action of groundwater along the joints of the surrounding rock in the direction of joints.When the inclination of the surroundingrock joints is less than 45°,the former occupies the dominant position,and with the increase of the incline angle,the latter’s role gradually increased. |
