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.

In situ measurements of cemented paste backfilling in an operating stope at Lanfranchi Mine

“…This anomalous behaviour has been observed a number of times and should not be dismissed as instrument malfunction, remembering that it has also been reported by other workers (Thompson et al 2012;Hasan et al 2013). Importantly, it is not recorded by the piezometers.…”

“…It is unclear why this occurs. Other in-stope surveys (Thompson et al 2012;Hasan et al 2013) observed the same phenomenon. After 3.7 days, the vertical stress cell displayed erroneous readings, indicating likely physical damage of the sensor (shown as a 'star' symbol in Figure 10b).…”

“…However, an unexpected response is evident thereafter, and has previously been noted by Thompson et al (2012) and Hasan et al (2013). Considering Figure 10 (location 1), after about 2.5 days filling stops and a rest period begins.…”

“…There is still a shortage of in-stope measurements of CPB performance in the literature. Exceptions include measurements carried out at Chimo Mine, Quebec (Hassani et al 1998), Doyon Gold Mine, Quebec (Belem et al 2004), Bouchard-Hébert mine, Quebec (Oullet & Hassani 2005), Alimak Mine, Ontario (Grabinsky et al 2007), Kidd Mine, Ontario (Thompson et al 2009), Çayeli Mine, Turkey (Thompson et al 2012), Kanowna Belle mine, Western Australia (Helinski et al 2011), and Raleigh mine, Western Australia (Hasan et al 2013). This paper provides results from recent full-scale monitoring of CPB during and post-backfilling at Lanfranchi Nickel Mine, Western Australia.…”

The impact of pore pressure boundary conditions in stope backfilling models

“…Thompson et al 2011) and the University of Western Australia (e.g. Helinski et al 2011;Hasan et al 2013) to collect in-stope measurements of pore pressure, total stress and temperature. An ability to back−analyse these stopes with realistic numerical models is essential for meaningful interpretation and ultimately the development of tools to facilitate backfill management.…”