Analysis of the Stress Distribution in Inclined Backfilled Stopes Using Closed-form Solutions and Numerical Simulations

Abstract

Backfilling is often used in underground mines to ensure stope stability and workers safety. Evaluating the stress state in the fill material and surrounding rock mass is a critical step for the design of backfilled stopes. The majority of analytical (closed-form) solutions to obtain the stresses have been developed for vertical openings. In reality, most mine stopes have inclined walls. Previous studies have shown that in such cases, the stresses developing along the hanging wall and footwall can be quite different. Recent investigations have also indicated that the stress transfer between the relatively soft backfill and stiff rock mass is typically not as well developed in inclined stopes, compared with vertical openings. In this paper, the authors first recall analytical solutions that have been proposed for evaluating the stresses in backfilled stopes with vertical and inclined walls. Numerical simulations are then used to assess the interactions between the backfill and rock mass. The influence of backfill properties and stope geometry (in terms of height, width and inclination) is examined. The stresses obtained from existing solutions and new simulations are then compared and discussed. This comparison points to significant differences, indicating that an alternate formulation is required to properly assess the stress state in inclined stopes.