Proposal of a Model Setup for Verification of the Origin of High Frequency Motion in Soil

Abstract

High frequency components of motion are typically measured in laboratory tests on shaking tables when investigating the dynamic response of soil subjected to harmonic excitation. The source of these high frequency components is often thought to be related to uncertainties of experimental setups. In contrast, a group of numerical and theoretical research works suggested potential physical explanations to high frequency components of motion as related to soil mechanical behavior including soil fluidization, cyclic mobility, pounding or unloading elastic waves. This paper presents a finite element numerical study of an example model setup designed to verify the origin of high frequency motion in soil as potentially related to the presence of soil elastic waves in the steady state response of nonlinear hysteretic soil. The soil is modelled with an advanced soil constitutive model within the general framework of hypoplasticity to account in a reliable manner for soil cyclic behavior. The results show that high frequency motion can be observed in the computations in free field and on a simple structure even though a simple harmonic sinusoidal input motion is introduced at the base of the model setup. It is shown that apparently this high frequency motion can be representative of soil elastic waves released in nonlinear hysteretic soil in the steady state response.