Experimental simulation and a reliable calibration method of rockfill microscopic parameters by considering flexible boundary

The discrete element method (DEM) is an important method to study the mechanical properties of rockfill materials, in which model parameters are critical to the accuracy of simulation results. This paper presented a reliable calibration method considering a flexible boundary to calibrate the microscopic parameters in the DEM. Firstly, the sensitivity of microscopic parameters to macroscopic responses was analyzed through the orthogonal test to narrow down the value ranges of microscopic parameters. Secondly, the nonlinear relationship between macroscopic responses and microscopic parameters was obtained using the response surface method (RSM). Thirdly, the optimal solution was derived by applying the mathematical programming method to obtain the specific microscopic parameters. Finally, the calibrated macroscopic parameters were used to study rockfill materials' micro- and macro- mechanical behaviors under different confining pressure conditions. It was showed that DEM can accurately simulate the rockfill compression process, and the parameter calibration method is reliable.