Application of design of experiments in microscopic parameter calibration for hard rocks of PFC^3D model

The design of experiments (DOE) is used to study the microscopic parameter calibration for hard rocks of PFC^3D model. Firstly, the sensitivity of microscopic parameters to macroscopic responses is analyzed through the Plackett-Burman design. The linear relationship between microscopic parameters and macroscopic responses is established. Then, the interaction between microscopic parameters is investigated by using the response surface method (RSM) and the nonlinear relationship between microscopic parameters and macroscopic responses is obtained. Finally, the problem is transformed into a nonlinear multiobjective mathematical programming problem, and the FGOALATTAIN function in MATLAB software is utilized to solve the problem. It can be found that when using DOE to calibrate the microscopic parameters, the PFC^3D model can well reflect the failure process of the rock under uniaxial and low confining compression conditions. However, the fitting results under high confining pressure is unsatisfactory. The method based on the PB design, response surface method and mathematical programming can reflect the sensitivity of the microscopic parameters, and the definite function expressions are obtained. At the same time, it can reflect more characteristics of rock mechanics by adding the constraints condition in the process of solving.