Research on the Nonlinear Mechanical Model of Cohesive Soil Based on Distinct Element Method

摘要

The mechiancal model of cohesive soil is very important for analyzing the complex mechanical characteristics and the dynamic responses of cohesive soil subjected to external forces. Distinct Element Method (DEM) is an effective tool for establishing a nonlinear mechanical model of soil with discrete particles. However, the traditional mechanical model of DEM is not comprehensive enough to describe the complex mechanical characteristics of cohesive soil. From the effects of liquid bridges on mechanical microstructure of cohesive soil, we found that the capillary forces and the dynamic viscous forces generated by liquid bridges had important effects on the interaction between soil particles in cohesive soil. Through introducing parallel bonds to simulate the forces generated by liquid bridges and adjusting the mechanical damping to reflect the dissipations of motions and collisions between soil particles, the nonlinear mechanical model of cohesive soil by DEM was established on the basis of the traditional mechanical model of DEM. The nonlinear mechanical model of cohesive soil by DEM could wholly reflect contact, slide, cohesion and energy-dissipated between soil particles in the cohesive soil subjected to external forces. The dynamic mechanical behaviors of cohesive soil subjected to a bulldozing plate with different cutting angles were simulated. Comparing the simulation results to the test ones, the nonlinear mechanical model of cohesive soil by DEM was validated to be applicable and accurate for analyzing the complex mechanical characteristics of cohesive soil. At the same time, the changing rules and the influencing factors of the dynamic behaviors of cohesive soil subjected to the bulldozing plate with different cutting angles were obtained from the mesoscopic motions of soil particles.