Stress distribution in anisotropic rock masses, ridges and valleys

Knowledge of the state of stress in rock masses is needed before engineering structures are constructed so that there is ample assurance that no structural failure could result from rock mass conditions. Stresses in rock masses consist of natural stresses (gravitational, tectonic and residual) and stresses induced by engineering structures. Isotropic solutions for the stresses in rock masses cannot be used for rock masses that are anisotropic or regularly jointed.; Several analytical elastic solutions for stresses in transversely isotropic, orthotropic rock masses subject to surface loads were proposed. However, these solutions are limited to rock masses with anisotropy oriented such that all horizontal planes are planes of elastic symmetry and bounded by a flat surface. Hence, the effect of the orientation of rock anisotropy and the type of loading surface was not considered. A more general solution was proposed by Lekhnitskii for the stresses in a generally anisotropic half space bounded by either a horizontal surface or a concave surface with a parabolic shape. Lekhnitskii's solution allows the planes of elastic symmetry in the half space to be inclined with respect to the surface load longitudinal axis. For the gravitational stresses in symmetric ridges or valleys, analytical solutions were not considered for anisotropic rock masses in the literature.; In this thesis, Lekhnitskii's solution is extended to include the influence of surface tractions parallel to the surface load longitudinal axis and to consider the half space bounded by a curved surface with a ridge or valley shape. Also, a new analytical solution for gravitational stresses in anisotropic ridges or valleys is presented using a perturbation method. Parametric studies are conducted to investigate the effect of several parameters on the stress distribution in anisotropic rock masses, ridges, and valleys subject to surface or gravitational loads. Factors considered include the shape of the ground surface, the type and degree of rock anisotropy and the orientation of rock strata or joint planes with respect to the surface loads.