Excavation of the Lift 2 Crusher Hydroset Chamber and Orepassin Seismically Active Conditions at Northparkes Mines

摘要

Northparkes Mines is a joint venture between Rio Tinto and thernSumitomo group and is operated by Rio Tinto to produce copperrnconcentrate from ore sourced from open cut and underground.rnUnderground ore is mined with an owner operator workforce using thernblock cave method from the E26 deposit,with the first lift of the cavernnow completed.Development of the Lift 2 block cave commenced inrnMarch 2001 using a contract workforce.rnThe Lift 2 Project required the mining of 14 700 m of decline andrnlateral development to establish a ew mining horizon at the 9450 levelrnand to develop two new conveyor declines.rnAlso included in the scope was the excavation of a Crusher chamber tornhouse the jaw-gyratory crusher.rnThis paper describes the excavation of the hydroset chamber andrnorepass that sit immediately underneath the Lift 2 Crusher chamber.Itrnincludes risk assessment,planning,development of method statementsrnand standard operating procedures,through to the excavation of thernorepass and the installation of ground support in seismically activernground.rnThere was a major ground failure in the backs of the conveyor feederrnchamber during its excavation,which affected the excavation of thernorepass due to its proximity to the breakthrough site.