Summary and Conclusions

Abstract

In order to assess the influence of rock anisotropy on in situ stress measurements from a quantitative point of view, knowledge of the directional character of the rock deformability is required. In this study, the latter is described using the constitutive relations of the theory of linear elasticity for anisotropic media. Directions of elastic symmetry are assumed to coincide with the apparent directions of rock anisotropy. The extent to which this assumption is applicable must always be investigated by testing rock specimens in the laboratory and in situ. Procedures are proposed in Chapter 2 to calculate the five and nine elastic constants of rocks that can be described respectively as transversely isotropic or orthotropic materials using unconfined, triaxial or multiaxial compression laboratory tests. If more than nine elastic constants are needed, the procedure becomes more complex but may be investigated as a possible model to describe the deformability of anisotropic rocks that present directions of anisotropy inclined with respect to each other.