Numerical simulation of resonant column tests on jointed rocks using DEM

Abstract

A resonant column apparatus can provide the wave velocities of geomaterials under torsional and flexural vibrations for a range of strain levels, within the elastic limit. The testing specimen is vibrated in its fundamental mode and the frequency that produces maximum strains in the sample is picked up as the resonant frequency. The wave velocities are obtained from the resonant frequencies and elastic moduli of the material can be calculated from the wave velocities. The paper presents the numerical simulation of the resonant column tests on jointed rocks by employing a distinct element method (DEM). The resonant frequency has been evaluated by monitoring the displacements at the edges of the sample during vibrations. Resonant frequencies of the testing jointed samples under long wavelength condition have been obtained under various strain levels and have been compared against that obtained from laboratory experiments. When the wavelength of propagating wave is much longer than the joint spacing, it is known as a long wavelength condition. The long wavelength propagation of waves is a general condition in earthquake engineering. The transmission of vibrations across joints has also been shown for the samples with multiple parallel joints.