Thermoelastic analysis of a geological repository with distributed decay heat sources by the image method in combination with a numerical integration scheme

Abstract

The disposal of nuclear waste involves thermo-mechanical reaction of the host rock to the buried waste – a distributed heat source that decays. To solve the problem within the half infinite space confined by the ground surface, an image method is developed. Specifically, a negative image of the heat source with the ground surface as the mirror, i.e. a mirrored heat sink is utilized so that the normal traction generated by the heat source can be counterbalanced, and a numerical scheme of integration of the classical Cerruti solution is developed to include the effect of tangential shear traction on the ground surface caused by the heat sources and their mirrored sinks. For a conceptual repository model, large thermal shear stress, tensile stress, and deformation occur at the corner, between adjacent drifts, and at the boundary of the repository area, respectively. For a prescribed thermal loading, it is more efficient to mitigate the thermo-mechanical effects through enlarging the pit spacing than increasing the drift spacing.