Abstract:

A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact. Soil is a typical granular material in nature. The concept of effective stress is one of Karl Terzaghi's most important contributions to soil mechanics. It is a measure of the stress on the soil skeleton (the collection of particles in contact with each other), and determines the ability of soil to resist shear stress. However, the soil skeleton is an imaginary concept, and it is hard to measure the geometric and mechanical properties. A few conflicts on its understandings are still remaining. The newly developed granular material mechanics may be helpful to provide insights to soil skeleton. We propose that skeleton is actually the particle connection diagram, and more importantly we found the interparticle forces were transmitted through quasilinear chain structures affiliated to the skeleton. It is necessary to compare the skeleton and force chains. In this work, a series of discrete element simulations were conducted on a uniaxial compression system consisting of 12,400 poly-dispersed particles. We find that skeleton corresponds to the geometric architecture of particle connection, while force chains sensitively response to external loadings though the skeleton is kept constant.

Key words: granular material, effective stress, force chains, soil skeleton