Stability Analysis Of Anchoring Surrounding Rock Of Deep-buried Caverns And Research On Optimization Of Support Under The Influence Of Multiple Factors

With the rapid development of the world economy,the exploitation and utilization of deep rock mass engineering has become one of the important research topics in the field of underground engineering.Because deep buried rock engineering occurs in the typical complex mechanical environment of "three high,one time and one disturbance",the surrounding rock has remarkable rheological characteristics under the combined action of many factors,which shows that the deformation of surrounding rock tends to be stable only after a period of time in the initial supporting.Therefore,it is of great practical significance to study the stability of the surrounding rock and the optimization of the supporting parameters of the deep buried cavern under the supporting conditions to ensure the safe construction of the deep buried rock engineering.On the basis of summarizing and analyzing the research results at home and abroad,this paper takes the deep buried surrounding rock after the prestressed bolt support as the research object,and through the systematic analysis of the stress characteristics of the prestressed bolt and the deformation factors of the surrounding rock,puts forward the inversion analysis method based on the stress of the bolt to study the deformation law of the surrounding rock.A fuzzy comprehensive evaluation model for the stability of the surrounding rock under the influence of multiple factors was established,and then the excavation and support scheme of the tunnel was optimized.The main research contents and results of this paper are as follows:(1)The stress characteristics and the position of the neutral point of the prestressed bolt are studied.After excavation and completion of initial support in deep buried cavern,coordinated deformation occurs between anchor bolt and surrounding rock.Based on the coupling principle of rock and bolt and the neutral point theory of bolt,a mechanical model of the interaction between the prestressed bolt and surrounding rock was established,and the mechanical characteristics of the prestressed bolt under the supporting condition were analyzed.According to the static equilibrium condition of the rod,the position of the neutral point where the shear stress on the surface of the rod is zero and the maximum axial force at that point are determined.(2)The deformation law of surrounding rock under the condition of bolt support is discussed.Based on the Mohr-Coulomb yield criterion and the theory of neutral point,the stress distribution in the elasto-plastic zone of the surrounding rock was analyzed under the initial supporting condition,and the analytical relationship between the maximum axial force at the neutral point and the plastic zone radius of the surrounding rock was established.The results show that the deformation range of surrounding rock can be analyzed by the maximum axial force of anchor bolt.(3)The main factors influencing the deformation of deep buried surrounding rock under the condition of bolt support are analyzed.The deformation of the surrounding rock is caused by the excavation disturbance,the geological strength index,the prestress of the anchor and the pore water pressure.Based on the analytical relationship between the maximum axial force of the rod and the plastic zone radius of surrounding rock,the theoretical formulas for the deformation range of surrounding rock and the displacement of the tunnel wall under the influence of multiple factors were deduced.The results show that the radius of plastic zone and fracture zone increase with the increase of excavation disturbance and pore water pressure,and decrease with the increase of geological strength index and anchor prestress.(4)A fuzzy comprehensive evaluation model for the stability of deep tunnel anchoring surrounding rock is established.Considering embedded anchor deformation characteristics of surrounding rock,in the basis of analysis of underground engineering stability evaluation methods,select saturated rock uniaxial compressive strength and rock mass integrity coefficient,ShenShuiLiang,degree of rock weathering,the excavation disturbance,bolt axial force,horizontal constringency and arch sinking as evaluation factors,build the embedded anchor fuzzy evaluation model,the stability of surrounding rockTo realize the timely dynamic analysis of the surrounding rock stability in the construction stage of deep buried cavern.(5)The optimization scheme of excavation reserve and bolt support parameters of deep buried cavern is put forward.In qinling mountains a deep buried under construction diversion tunnel as an engineering background,the fuzzy comprehensive evaluation on the stability of the tunnel anchorage of surrounding rock,on the basis of the above theory is used to calculate the initial supporting anchor rod under the condition of neutral point position and scope of tunnel surrounding rock deformation and displacement of tunnel wall,and then determine the reserve the reasonable tunnel excavation deformation and its bolting parameters.Combined with the field monitoring data,the engineering applicability of the above research results is verified.The research results have positive significance for deformation control and safe construction of deep buried cavern.