Horizontal pressure on barricades for backfilled stopes. Part II: Submerged conditions

Abstract

This paper presents a method to calculate the pressure generated by submerged backfill on barricades (or bulkheads) located in drifts at the base of mine stopes. The paper complements Part I (see companion paper, this isue), which presents an analytical solution for the pressure on barricades when the backfill is in drained conditions (after the pore-water pressure has dissipated). The solution presented here applies shortly after backfill deposition, for undrained conditions. In this case, the effect of pore pressure cannot be neglected as it may be critical for the response of barricades. The solution is developed for totally or partly submerged backfill (with the water table at various elevations). Experimental testing and numerical modelling results are used to validate the proposed equations. Both numerical and analytical results show that the total pressure on barricades can be significantly increased by pore pressure, while the effective stress is decreased in the access drifts (compared to dry or drained conditions). The proposed solution provides a simple method to obtain a realistic estimate of the total and effective stresses, and can thus be used as a basis for barricade design.