Speaker
Description
Soil and rocks are not so elastic as expected, both present damped and delayed mechanical behavior, called viscoelasticity or rheology. Deviation of static and dynamic elasticity moduli of rocks can also be explained via rheology, furthemore, long term measurements prove that motion of the soil around underground facilities may be relevant even years after the construction. Although elastic waves are dispersion and attenuation free, wave propagation in viscoelastic media is dispersive due to the internal dissipation of the media. This behavior detunes the wave propagation velocities and showing futher dissipative and dispersive effects, thus modifying the shape of the wave signal and reduces the amplitude, which may affect the filtering and mitigation of Newtonian noise.
In the talk we present a thermodynamically consistent family of rheological models called Kluitenberg–Verhás model, which covers Hooke’s elasticity, Kelvin–Voigt, Maxwell, Poynting–Thomson–Zener and other models as special cases. Mathematical properties, dispersion relations, wave propagation velocities and attenuation of some models are analyzed. We demonstrate a self-developed symplectic-like staggered grid finite difference method, via reliable simulations of elastic as well as rheological wave propagation problems can be realized both in one and more spatial dimensions. Thanks to the simplicity of the scheme, numerical originated dispersion and dissipation errors can be eliminated, furthermore, the method numerically also preserves total energy. Finally, we briefly review some uniquely developed experimental methods for determining the rheological parameters.
