Full scale experiments on the effectiveness of a drainage system for cemented paste backfill

Abstract

This paper presents full-scale experiments on cemented paste backfilling in two operating mine stopes located at Raleigh mine, Kalgoorlie, Western Australia. The experiments compared the behaviour of the cemented paste backfill (CPB) in a drained stope and an undrained stope. The drained stope was equipped with a drainage system at the barricade, whereas the undrained stope was not. Total stress and pore water pressure sensors were installed to measure the stress within the fill mass during and after backfilling. The stress behaviour was expressed by the normalised total horizontal pressure and the normalised pore water pressure. It was found that the normalised total horizontal pressure and the normalised pore water pressure behaviour at the two stopes were significantly different. The drainage system increased the consolidation of the fill and reduced the pressure acting on the barricade. The pore water pressure measurement in the undrained stope showed a non-linear accumulation at the barricade. In contrast with the undrained stope, the stope with the drainage system showed significant pore water pressure reduction and the accumulation of pore water pressure at the barricade no longer occurred. The findings described in the paper contribute to critical design and management aspects such as barricade stress, filling rate, and curing strategy, with an ultimate goal of reducing costs while ensuring safety underground.