Numerical and analytical solutions for the pore water pressures within barricades made of waste rocks

Stope backfilling is a commonly used in underground mines. In many cases, the backfill is initially saturated with water to facilitate transportation from the surface to the underground openings. A barricade is required at the base of the stope, near the drift entrance, to retain the backfill in place. An increasingly popular practice is to use waste rocks to construct the barricade. Additional work is however needed to investigate the hydro-geomechanical behaviour of such type of barricade. In this report, the distribution of pore water pressure in barricades made of waste rocks is analysed. An analytical solution, based on a combined artesian-gravity steady-state flow condition, is introduced and applied to estimate the pore water pressure along the base of the barricade. Results from numerical simulations are then used to assess the validity of the analytical solution and to evaluate the effect of various influence factors. The results show that the proposed solution generally predicts well the distribution of pore water pressure obtained from the numerical calculations. This analytical solution is extended to evaluate the pressure along the full height of the barricade.