| As a natural geological body,rock mass often has a lot of uncertainty and complexity in engineering practice.How to calculate and accurately determine the mechanical parameters of rock mass is a thorny problem.In the neighborhood of rock mechanics,a considerable part of the subject is based on the stability evaluation of roadway surrounding rock,the calculation of surrounding rock stress and displacement field of roadway.Generally speaking,It is a common method to solve the above problems through mechanical calculation.Therefore,after determining the mechanical calculation model of roadway engineering,how to give the approximate parameters needed for calculation is in accordance with the actual engineering parameters,such as the mechanical properties of surrounding rock?the initial ground stress and so on,has become the key to the problem.The traditional analogy method and expert experience method can determine this kind of mechanical parameters to a certain extent,but the technical quality of project personnel is often required to be high,and some subjective factors are mixed in the process of evaluation.It is difficult to guarantee the accuracy of parameters.Laboratory test method is a commonly used method at present,but the mechanical properties of rock are often obtained by laboratory test method,which is very different from that of rock mass under complex ground stress.Therefore,how to make the determination of mechanical parameters of surrounding rock develop towards precision and data,and become engineers to carry out in-depth development.The research,which needs to be solved urgently.In this paper,2-1051 roadway in Zhaowu Coal Mine is taken as the research object,and the displacement back analysis and calculation are carried out by using the monitoring data of the surrounding displacement of the roadway.Based on the principle of approximate substitution,the analytical solution of the displacement of arch roadway in isotropic rock mass under the condition of three dimensional unequal compressive stress is derived,and the influence degree and sensitivity are used as the evaluation criteria for the reversibility of roadway displacement inversion analysis.The mechanical parameters of elastic-plastic materials in accordance with Moore-Coulomb(Mohr-Coulomb)failure criterion(elastic modulus E,Poisson's ratio ?,internal friction angle ?,cohesion C),and initial ground stress(horizontal ground stress p,vertical ground stress q)are carried out.Through the analysis of influence degree and sensitivity,the parameters of sensitivity and influence degree are extracted,including elastic modulus E,internal friction angle ?,cohesion C,as inversion parameters,aiming at the arrangement of measuring points.The numerical simulation analysis is carried out when the stress direction and horizontal direction of the boundary of the model are 30?,45 ? and60,respectively,and the optimal arrangement of displacement measuring points is determined.Based on the field monitoring data of displacement at each measuring point of roadway section in Zhaowu Coal Mine,the intelligent calculation method-BP neural network algorithm is used to train the test samples,and the MATLAB toolbox is used to realize the program to determine the elasticity.The values of modulus E,internal friction angle ? and cohesion C are 3.82 Gpa,36.45? and 1.07 Mpa.Finally,the mechanical parameters of surrounding rock of roadway obtained by back analysis are analyzed forward.The displacement law obtained by forward analysis is compared with the displacement convergence law measured in the field,and the feasibility of inversion of mechanical parameters of roadway... |
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