HOEK-BROWN Criterion Parameter Optimization And Its Applications In Engineering

With the sustained, stable and rapid development of China's economy and the continuous improvement of social demand,underground engineering has made great development. Construction of underground engineering such as tunnel, deep mine, etc. enter a new era.It brings opportunities as well as challenges for the development of rock mechanics. How to obtain the accurate mechanical parameters of rock mass is a big challenge. This paper has studied the Hoek-Brown criterion used commonly in geotechnical engineering. By studying the expression form and the different methods for selecting mechanical parameters about the criterion, two new accurate methods for selecting mechanical parameters are proposed. The research presented in this thesis can be summarized as follows:(1) The new method for selecting geological strength index (GSI) is proposed. The method is based on the Hoek-Brown criterion and microseismic monitoring technology. By using the method, the mechanical parameters of rock mass under complex conditions can be obtained accurately. In addition, the equivalent Mohr-Coulomb criterion model is incorporated into the FLAC software by using FISH platform and the rock mechanics parameters in the proposed model are determined using microseismic monitoring data. And the proposed method is used to analyze the stress fields around the 8103 working face of Tashan mine in Datong and obtain the moving law of overlying strata for longwall top coal caving.(2) The four Hoek-Brown criterion parameters have been studied using the sensitivity analysis theory and the orthogonal design method.Results from sensitivity analysis indicates that the geological strength index (GSI), the degree of disturbance to rock mass D, the rock mass contant mi and the rock uniaxial strength ?ci have different influence on the dispalacement of the tunnel. The order for parameters is GSI, D, ?ci and mi. It can be found that the GSI has a highly significant influence,the D has significant influence, ?ci and mi have a little influence.(3) Using the results of sensitivity analysis and the displacement equation of cavern surrounding rock, the nonlinear regression model(NLRM) of Hoek-Brown criterion has been proposed. In developing the above-mentioned method, the uniform design and FLAC3D software are used. And we develop a reasonable back analysis methods and procedures by leading into differential evolution (DE). The method overcomes the problem that operation time is too long by repeatedlyusing the FLAC3D software.(4) By using the uniform design and FLAC3D software and combining the monitoring data of Qingdao Metro Line 3, the coefficients of NLRM can be determined. We use the proposed back analysis method to calculate the GSI values of 10 different conditions. And then, we establish the relationship between GSI and rock mass ultrasonic velocity(Vp) using the linear fitting method and obtain the GSI-Vp formula.Finally, we verify the GSI-Vp formula and provide a new method for engineering to accurately obtain the GSI values.