Abstract
The article summarizes, on the basis of availablu experimental data, current knowledge of anisotropic behavior of finegrained soils. The general form of anisotropic stiffness matrix is presented first, and the methodology of calibration of every single variable is developed.
It is demonstrated that complete experimental calibration of all variables occurring in anisotropic stiffness matrix requires a wide experimental program. This involves shear stiffness measurement by shear wave propagation and triaxial tests with local displacement transducers at various stress paths.
An alternative to these measurements are the empirical relations that can be used for approximate estimation of anisotropy coefficients when shear moduli ratio is known. In the next part of article, the dependence of anisotropic stiffness matrix coefficients on state variables is summarized.
It is shown that in case of fine-grained soils (unlike coarse-grained soils), we can assume anisotropy coefficients to remain constants during the course of loading, independent on soil state. The same assumption is valid also for Poisson's ratios.
It is ecessary to consider the dependence of moduli on stress state and on void ratio only. Subsequently, it is shown that the influence of stress can be taken into account by considering the influence of mean stress.
The proposed anisotropic model will be used as a component of advanced non-linear models for behavior of fine-grained soils in the range from very-small to large strains.