Method of stress calculation in rock mass around Underground openings, considering unit weight

Abstract

The practical calculation of rock mass deformation around an underground opening accounts for the unit weight of the rock mass by solving a complimentary problem on “weightless” rock mass. A domain with an opening is bounded by a plane with the preset zero vertical displacements, which enables taking into account difference of pressure along the height of the opening. This solution, with the adequately selected boundary conditions, is added with stress field of an intact rock mass and offers zero boundary conditions at the future opening perimeter, however, the issue on the validity of setting boundary conditions at the lower boundary of the calculation domain remains yet to be handled. This article presents a phenomenological model of rock mass deformation to answer the set question. It is taken into account that action of roof rock weight coincides with the orientation of tensile stresses at the opening perimeter and differs from it in the floor. The author thinks it is required to add the class of inverse problems of rock mechanics with the problems directly accounting for rock weight.