A Microscale Shear Wave Velocity Model of Earth-Rock Aggregate

With the recent construction boom, the stability of earth-rock aggregate (ERA) structures become a prominent problem. The ERA is essentially a heterogenous aggregate of randomly stacked particles of varied sizes, the gaps between which are filled with liquid and gas phases. However, the existing theories on geotechnical mechanics cannot accurately describe the mechanical behavior of this special material. To solve the problem, this paper treats the ERA as a set of as a set of randomly stacked spheres, which are equivalent to soil and rock particles in the ERA and have the same radius and material properties. Drawing on the particle contact theory, the total number of coarse particles in the ERA was calculated by the probability density function relative to the mean particle size (sieve diameter), followed by derivation of the equivalent radius of coarse particles. Next, the particle shape correction coefficient (PSCC) was introduced to obtain the equivalent shear modulus of the ERA, according to the relationship between mean stress in the ERA and the micro-contact force between particles. After that, the microscale formula of shear wave velocity was deduced from the macroscale formula. Finally, the effects of multiple parameters on shear wave velocity were quantified in details. The results show that the shear wave velocity of the ERA is greatly affected by the void ratio, elastic modulus, and the PSCC, but has little to do with effective internal friction angle, Poisson's ratio, and coordination number of the ERA particles.