Influence of pore water pressures on the stress state in inclined backfilled stopes

ABSTRACT: Backfilling is commonly used in underground mine stopes to improve openings stability and workers safety. Evaluating the stress state in backfilled stopes and surrounding rock mass is a crucial step for design. Various investigations have shown that settlement of the soft fill material after placement in relatively narrow stopes tends to produce shear stresses along the walls, leading to an arching effect associated with a load transfer from the backfill to the stiff rock mass. Most stress analyses reported in the literature have been obtained for dry (or fully drained) backfill in openings with vertical walls. In many cases however, there are significant pore water pressures in backfilled stopes, where the walls are inclined. This article presents an analytical solution and recent simulations results for the stress state in partially (or totally) submerged backfilled stopes with walls having different inclination angles. The influence of the backfill strength parameters is also assessed. The numerical results are used to validate (in part) the proposed solution for the total and effective stresses in inclined backfilled openings.