Correlation between mechanical and ultrasonic responses for anisotropic behavior of soils.

Abstract

An attempt has been made to develop a Non Destructive Testing (NDT) procedure for the characterization of induced anisotropy in geologic materials and to compare, to quantify and to correlate such response with the anisotropic response as predicted by the constitutive model. Herein, the ultrasonic NDT method is used as a tool to quantify the anisotropic response of the material and the δ₁ model of the HISS series of models is used to describe the mechanical anisotropy. A unique and novel testing procedure which includes three-dimensional mechanical (destructive) testing combined with ultrasonic testing of cubical (cemented sand) samples under various stress paths has been developed. Mechanical response is presented in the form of stress-strain and volumetric responses, while, the ultrasonic response is presented in the form of wave signatures, velocities and attenuations. Also, special tests have been performed to observe experimentally the anisotropic response of a material in shear stress paths. The quantification of mechanical anisotropy is made by using the δ₁ model, while, the ultrasonic velocity and attenuations are used to define the ultrasonic anisotropies. The parameters which define the δ₁ model are determined based on the test results, and the suitability of the model is verified by back-predicting the tests. Correlation functions which relates the mechanical anisotropy with the velocity anisotropy and the attenuation anisotropy have been developed, based on the observed data and on the principles of mechanics. The potential applications of such functions are also discussed.