| The area where karst landform is widely distributed.In the process of tunnel construction,cave collapse,water and mud inrush and other hazards will occur,which will do a great threat to the tunnel construction process and even the later operation and usage.Therefore,it is necessary to study the influence of karst cave on traffic tunnel safety.Taking huangdongpo tunnel in Guizhou Province as the engineering background,in the condition of the unfavorable factors such as poor geology and hydrogeology in karst area,shallow buried depth of tunnel,poor stability of cavern in shallow buried excavation and so on,this paper systematically analyzes the influence of karst cave location,scale and construction technology on tunnel safety.(1)By analyzing the distribution characteristics and development law of karst in Guizhou,aiming at the distribution and characteristics of karst caves in shallow buried tunnels in Guizhou,a numerical simulation model is established and calculated.The influence of different scales and spacing on the displacement of tunnel surrounding rock and the stress of supporting structure is deeply analyzed where karst caves are located at the bottom and side of the tunnel,then the law is summaried.(2)Combined with the engineering geological conditions and construction scheme of Huangdongpo Tunnel,through the analysis of the displacement of surrounding rock and the stress of supporting structure,the influence of tunnel excavation method on the tunnel structural mechanical effect is studied.The study shows that the double-wall tunnel guide method has the best effect.Combined with the required time limit and construction difficulty,the excavation method is determined as CRD method.(3)Aiming at the specific karst problems of Huangdongpo tunnel,the karst treatment plan is taken,and the influence of grouting filling of karst cave,strengthening tunnel advance support,different excavation dimensions and supporting structure on the construction safety of karst tunnel is analyzed through numerical simulation system,and the construction plan is finally determined.The surface subsidence,vault subsidence,clearance convergence and deformation rate are compared with the field monitoring data,and it is found that the variation rules of simulated values and monitored values are roughly similar.Finally,the main work of karst detection is introduced and the comprehensive prevention and control measures of karst in different directions and sizes are taken,which can provide reference for similar projects. |
PDF Full Text Request