Research On Stability And Control Measures Of Surrounding Rock Of Chaoyang Tunnel

With the rapid construction of highways on a large scale,the transportation between cities has become more and more convenient.In the construction of highway tunnels,the proportion of highway tunnel construction is increasing.Tunnel construction will encounter complex geological conditions,joint surface development,etc.,especially in the process of tunnel excavation,resulting in the instability of tunnel surrounding rock,and it is urgent to solve the selection of supporting parameters and the safety of construction scheme in tunnel excavation.Therefore,based on the Chaoyang Tunnel,this paper conducts research on the stability and supporting measures of the surrounding rock of the tunnel,and improves the stability of the surrounding rock of the tunnel from the aspects of optimizing the supporting parameters and the optimization of the construction method.Chaoyang Tunnel is located in the southwest foothills of Changbai Mountain,the overall direction of the mountain is north-east,the tunnel passes through both shallow buried section and deep buried section,and the excavation near the mouth of Chaoyang Tunnel is a typical shallow buried joint tunnel excavation.Aiming at the joint excavation of Chaoyang Tunnel,this paper studies the stability and control measures of surrounding rock of jointed rock mass tunnel.Firstly,based on the parameters obtained from the test of tunnel petrophysical and mechanical parameters,a discrete element model of joint tunnel is established,and the influence of joint factors(joint position and joint inclination)on the stability of surrounding rock of joint tunnel is analyzed,and the effect of spray anchor support on the stability control of surrounding rock of joint rock mass tunnel is studied based on the actual engineering overview of Chaoyang Tunnel.Under the excavation of the step method,the reasonable step length was selected as the control measure,and the stability control effect on the surrounding rock of the Chaoyang joint tunnel was analyzed.The research contents of the thesis are as follows:(1)The discrete element model of Chaoyang tunnel is established.Based on the analysis of the geological situation of Chaoyang Tunnel and the joint production status of the tunnel,based on the physical and mechanical parameters and geometric structure parameters of the surrounding rock of Chaoyang Tunnel,the joint position and joint inclination angle and other joint production parameters of the surrounding rock were summarized,and the 3DEC model of the joint rock mass tunnel was established.(2)The influence of joint factors(joint position and joint inclination)on the stability of tunnel surrounding rock was studied.Using the established tunnel discrete element model,the influence of joint position and inclination angle on the stress strain of surrounding rock was analyzed and studied.The results show that tunnel joints,when the joint inclination angle at the shoulder is30° and the tunnel joint inclination angle at the vault is 15°,the tunnel is prone to instability.(3)The influence of spray anchor support on tunnel stability was studied.A tunnel stability analysis model considering the supporting structure was established,and the displacement and stress-strain laws of the surrounding rock of the tunnel under different combinations of support types were analyzed,and the stability of the surrounding rock after the anchor support was judged by the allowable relative convergence displacement of the surrounding rock.After analysis,it is proposed that the support scheme of Chaoyang tunnel is 3.5m for the length of the anchor and 250 mm for the thickness of the lining concrete.(4)The optimization research of Chaoyang tunnel excavation method was carried out,the influence of different excavation step lengths on the displacement of tunnel surrounding rock was analyzed,and finally a reasonable excavation step length was optimized and selected,and the stability control measures of Chaoyang Tunnel joint rock mass were proposed.Compared with the monitoring results,it shows that the optimized Chaoyang tunnel excavation scheme is feasible.