The Influence of Void Ratio on Small Strain Shear Modulus of Granular Materials: A Micromechanical Perspective

摘要

The small strain shear modulus G_(max) of granular materials is highly dependent on their current void ratio and stress state, generally expressed as the famous Hardin and Richart equation. Various forms of void ratio functions have been proposed, either based on experimental or theoretical research. It is noted that each of them can be applied for a certain soil within a limited void ratio range. Micromechanical studies on the influence of void ratio on G_(max) are conducted in this paper, using Discrete Element Method. After each sample being isotropically consolidated, shear wave velocity is measured by applying a velocity pulse to the transmitter in a certain direction, and monitoring the corresponding average velocity of the receiver. The capabilities of various existing void ratio functions are examined, together with the relationship between coordination number and void ratio, distribution of coordination number, as well as the contact force network. The void ratio effect on G_(max) is further explained in terms of the wave travel length and the travel time for different contact connectivity networks.