| The paper uses the method of reliability calculation to optimize and verify the feasibility of the surrounding rock support parameters of the hydraulic tunnel project through the fissure fracture zone in order that the support parameter design will be more scientific,more rigorous,and will better reflect the nature of the tunnel weak rock problem.Based on the investigation and study of a large number of research,this paper summarizes the principle of the supporting mechanism of the New Austrian Tunnelling Method and the advantages and disadvantages of the excavation method,as well as the characteristics of the surrounding rock through the fault fracture zone.According to the summaries and the overview of engineering of the hydraulic,this paper deeply discusses the effective method of tunnel excavation.Based on the particularity of the surrounding rock support in the fault zone,this paper uses the FLAC3 D software to simulate the surrounding rock support parameters by means of the upper and lower step excavation support.The excavation,support and excavation of the tunnel are simulated.The convergence of the surrounding rock and the stress redistribution,and the reasonable steel arch spacing is 0.8m,the bolt length is 4m,the bolt ring spacing is 0.7m and the shotcrete thickness is 40 cm.According to the monitoring and measurement of the support construction in site operation,the vault subsidence and the peripheral convergence of the surrounding rock and the fault zone are compared respectively,and the final displacement of the vault settlement is deduced by the regression curve.Based on the same type of the fault fracture zone,this paper conducts the grouping experiment of the optimized parameters and the conventional parameters of the surrounding rock,and respectively analyzes the surrounding rock deformation,the shotcrete pressure,the inner and outer stress of the steel arch,and the initial support rock.The results of the experiment show that the stability of the surrounding rock of the faulted fracture zone can be maintained by the support of the experimental optimization section,while the initial design parameters are destroyed in the arch and the upper part of the surrounding rock.Through the data from the monitoring and measure and the analysis of the stability of the surrounding rock,the numerical simulation of the parameters can be carried after the fissure fracture zone rock and maintain stability.Based on the Response Surface method,this paper incorporates the Monte Carlo data acquisition form,and calculated the structural reliability of the fault section of the hydraulic tunnel in a simulation.The calculated reliability ? value is the largest at the arch and the smallest in the upper part of the arch.The inflection point appears in the one third of upper part of the arch,and then gradually becomes larger.When it reaches the peak value,it turns to become smaller until the arch to reach a small value,and the trend of the previous numerical simulation and field observations compared to the distribution is basically the same.Since such analysis method for calculating the credible degree in a way of simulations combined with monitoring.There is a certain promotion value in an actual underground engineering. |
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