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Effects of particle shape and contact law on the low-strain stiffness of granular media

Granular soils and other media generally consist of a collection of discrete particles having a broad range of shapes. Variations in particle shape affect the macro-scale stiffness parameters and response characteristics of these media.

Discrete Element simulations were conducted to assess and quantify the effects of particle shape and contact law on the low-strain shear stiffness properties of granular soils. Soil grains of different shapes were modeled by clumping spheres having various levels of overlap. The conducted analyses showed that particle shape influences solely the F(e) term in the expression of low strain shear modulus as a function of void ratio (e) and mean confining stress (o). Particle sphericity was found to be the main consequential shape parameter. Hertz-Mindlin and Goddar-Mindlin laws were employed to investigate the effects of smooth and angular interparticle contact conditions. The contact law was found to affect directly the confining stress exponent. A law reflecting an angular inter-particle contact was shown to be necessary to obtain the stress exponent n = 0.5 commonly used with granular soils.

Author(s):

Mourad Zeghal    
Rensselaer Polytechnic Institute
United States

Chrysovalantis Tsigginos    
Drexel University
United States