Calibration of discrete element model parameters for cohesive soil considering the cohesion between particles

Objective To calibrate contact parameters and contact model parameters for the cohesive soil discrete element model.

Method The Hertz-Mindlin with JKR contact model which consider the cohesion between particles was employed for the repose angle simulation test. The simulation test was based on the results of physical test for angle of repose. The key parameters including JKR surface energy, coefficient of restitution, coefficient of static friction and coefficient of rolling friction were obtained from the GEMM (Generic EDEM material model) database. A Box-Behnken design was then used to perform the simulation test for repose angle in above value ranges.

Result The regression model for repose angle was acquired from the test results by multiple regression analysis. Analysis of variance showed that the model was extremely significant, and the relationship between experimental factors and repose angle was fitted to a quadratic polynomial with complex liner and quadratic interactions. The optimized solution was acquired by using 40.45° as the target of repose angle. The optimized solution was as follow, JKR surface energy was 7.91 J·m^-2, coefficient of restitution was 0.66, coefficient of static friction was 0.83, and coefficient of rolling friction was 0.25. The optimized solution was then used for simulation test and the obtained repose angle was 39.73°. The simulation test was highly matched with physical test on both angle and shape of repose.

Conclusion For the soil sample used in this research, the optimized parameters can be used for further simulation of kinematics and dynamics between cohesive soil and soil contact components, and for providing the motion characteristics of cohesive soil under the actions of soil contact components.