Study On Stability Of Surrounding Rock In Cross-connecting Section Of Tunnel And Treatment Measures Of Existing Tunnel

With the development of economic construction and the needs of the school’s scientific research level,a cave laboratory has been difficult to meet the existing need.It is in line with the school’s planning and development to increase on the original basis,so the mechanical behavior of multiple and manifold cross-connect tunnels Research becomes the primary problem that must be solved.In the process of the two tunnels being continuously close and finally intersecting and connecting,the blasting load generated by the drilling and blasting method and the stress redistribution at the cross-connecting section of the tunnel will adversely affect the project.At the same time,different geological conditions will also have different effects on the stability of the surrounding rock at the intersection of the tunnel.If it cannot be effectively treated,it will cause the existing tunnel lining to crack,flake,fall off,and even cause the existing tunnel to collapse and destruction.Therefore,it is very important to pay attention to the stability of the surrounding rock of the tunnel during the construction process,and to study the changes of its mechanical behavior and its impact on the surrounding environment.Relying on the cave laboratory of Huazhong University of Science and Technology’s precision gravity measurement research facility,the research method of the combination of theoretical analysis,on-site measurement and numerical simulation is used to analyze the mechanical behavior of the tunnel junctions and the existing tunnel treatment measures.The thesis mainly draws the following conclusions:(1)Comparative analysis of the vibration speed,stress and displacement of various parts of the existing tunnel through the numerical simulation results.It was noted that the side wall of the existing tunnel’s blasting is the area most affected by blasting,and the maximum vibration speed,stress and displacement appear in the blasting Near the sidewall.The vibration velocity at the maximum vibration velocity point of the side wall of the blasting site experienced two increases and two decreases;the stress and displacement of the side wall of the side blasting increased with time and then decreased.(2)Comparing the reinforcement scheme of the existing tunnel steel arch,it is found that the closer the spacing of the steel arch is,the equivalent elastic modulus of the existing tunnel increases,and the vibration velocity and vibration velocity of the surrounding rock at the side wall of the existing tunnel under blast The greater the stress;when the elastic modulus of the existing tunnel is within a certain range,with the increase of the elastic modulus,the displacement of the surrounding rock at the side wall facing the explosion decreases,when the elastic modulus of the existing tunnel exceeds a certain critical value At this time,the displacement of the surrounding rock at the side wall of the blasting side increases.(3)Through numerical simulation to study the influence of surrounding rock grade on the stability of tunnel cross-connect section,it is found that surrounding rock grade has little effect on the principal stress of surrounding rock,and has a greater influence on the displacement of surrounding rock of the tunnel.As the grade of surrounding rock increases,the displacement of surrounding rock decreases,and the rate of change also decreases.(4)When comparing the numerical simulation results with the actual measured values,it is found that there are some deviations in the measured values,correction values,and numerical simulation results of on-site vault sinking and peripheral convergence,but the difference is within the engineering error range,indicating that the numerical simulation results are The project has a certain guiding role and reference value.