Three-Dimensional in Situ Stress Analysis of Rock Masses Perturbed by Irregular Topographies and Underground Openings

Abstract

Abstract : The overall goal of this project is to develop a new and efficient boundary element method (BEM) program for the stress analysis of 3-D anisotropic rock masses that are perturbed by irregular topographies and underground openings. This stress analysis will provide direct information on the best (or optimal) selection of the surface location and hit angle for a penetrator. We have identified three tasks to achieve this goal, which include theoretical and analytical development; computational and numerical development; and laboratory investigation and field validation. This final technical report presents our accomplishments related to the first and second tasks, that is, the theoretical and analytical development, and computational and numerical development. First, the analytical solution and numerical implementation are presented for elastostatic displacement Green's function for 3D rock masses of general anisotropy. Excerpts from the authors' FORTRAN code are included. A numerical algorithm for the calculation of the derivatives of the Green's displacements and stresses is also introduced. Secondly, these Green's functions are incorporated into a BEM code developed by the authors. Thirdly, numerical results of Green's displacements, stresses and stress derivatives are presented and compared to the closed-form solutions for transversely isotropic rocks. Finally, the BEM code based on the current Green's functions is tested and the numerical results are compared to those using a BEM code based on the exact Green's functions. It is shown that the Green's functions derived in this report are accurate and the corresponding BEM code is correct. This BEM code is now ready for the laboratory comparison and field validation.