The Use of Fibre Reinforced Shotcrete Fill Retaining Walls with Engineered Drainage System to Achieve Safe and Efficient Hydraulic Fill Placement in Underground Voids

2007

Tony Grice,

Mine backfill retaining wall failures have been associated with economic losses, fatalities and interruption to mine production. Mine operators want to eliminate these fill retaining wall failures. Fibre-reinforced shotcrete is increasingly being used to construct underground fill retaining walls with engineered drainage systems to improve safety in hydraulic fill operations. The fill retaining wall failures associated with hydraulic filling could be avoided through an integrated approach to mine backfilling considering the consistency of the fill, drainage regimes, pore water pressure and fill pressure and providing mechanisms to improve drainage and reduce water and fill pressures. The author was involved in the development of two types of fibre reinforced shotcrete fill retaining walls, namely “arched walls” and “buttressed planar walls” to withstand high fill and water pressures. Since 2000 more than 750 of these new structures have been successfully constructed and several million tonnes of hydraulic fill have been placed underground using these new types of fill retaining walls in one of the mines in Australia. The research conducted by the author in the above mine site between 2000 and 2006 has resulted in the development of “the deep fill drainage” system that helps to reduce the water pressure associated with the hydraulic filling in the access drives and also on the fill retaining walls. This paper will present the design, construction and field monitoring aspects of the fill retaining walls with engineered drainage system together with case studies.

Mots Clés: Water table, Safety, earth pressure, Hydraulic, Retaining-walls, Buttressed, Arched, Deep-drainage, pore water, Shotcrete