Model of block media taking into account internal friction

TL;DR

This paper presents a viscoelastic block medium model incorporating internal friction with rheological elements, analyzing its impact on wave dispersion and geomechanical responses through numerical experiments.

Contribution

It introduces a novel rheological model of internal friction for block media, enabling accurate simulation of viscoelastic behavior and wave dispersion effects.

Findings

The model can match a given quality factor within 5% accuracy.

Quality factor significantly affects low-frequency dispersion.

Attenuation of surface wave amplitudes depends on the Q-factor.

Abstract

The block medium is modeled by a discrete-periodic spatial lattice of masses connected by elastic springs and viscous dampers. To describe the viscoelastic behavior of the interblock layers, a rheological model of internal friction with two Maxwell elements and one Voigt element with the quality factor of the material as the determining parameter is proposed. Numerical experiments show that, within the framework of this interlayer model, it is possible to select the viscosity and stiffness of the Maxwell and Voigt elements so that the quality factor of the material differs from the given constant value by no more than 5%. In the one-dimensional case, within the framework of the proposed model, the influence of the quality factor on the dispersion properties of a block medium is studied and it is shown that the greatest effect of the quality factor on the dispersion is observed in the low-frequency part of the spectrum. In the three-dimensional case, within the framework of the proposed model, some geomechanical problems are numerically studied for a block half-space under the action of a surface concentrated vertical load. Namely, the attenuation of the velocity amplitudes of surface blocks was studied depending on the Q-factor under step action and under the action of a Gaussian pulse. In addition, we study a layer on the surface of a half-space under the action of a concentrated vertical impulse load in the case when both the layer and the half-space are block media but have different properties.