Comparison of the Shear Stress-Displacement Relationships of Semi-Empirical and Discrete-Element Models

摘要

A two-dimensional discrete-element model for the interaction between track link and soil is presented. The model was developed using PFC2D code and two different particles: sphere and clump of two spheres. The soil parameters of the model were found using Hertzian contact theory. Based on the model and soil parameters, simulations of tri-axial tests and calculations of the internal angle of friction Φ and cohesion were preformed. The simulation results showed that the internal angle of friction cannot exceed the value of 0.65 when using the spherical particles. Based on the clumped particles model, simulation shear tests of two plates (lengths 100 mm and 150 mm) were performed under different soil conditions, vertical loads, and grouser lengths. A curve fitting of the simulation results was performed using three semi-empirical models – Bekker, Janosi, and Wong – for the shear stress-displacement relationship. The best fitting was achieved using Wong's approach. The simulation results of the grouser effects were compared with Bekker's grouser approach and McKyes's formulation for soil–blade interaction. In most of the cases, the results of Bekker's model were the lower bound and McKyes's model, the upper bound of the DEM simulation results. Some mechanical properties of the soil were determined using simulation results of the shear tests. We found that the plate length has only minor effect on the soil properties.