Ground support strategy for optimisation of time schedule, Oyu Tolgoi Underground Mine

Abstract

Oyu Tolgoi is an underground block cave in the initial development stage, where rapid development, yet comprehensive, ground support is required to begin undercutting and start production. High variability in the rock mass, high stress and deep mining requires various ground support standards and sequences to provide initial stability during development and long-term stability for the production stage. Different strategies were developed for ground support and reinforcement that support short-term and longterm stability at the appropriate time, to optimise the development rates and reduce rework. The different approaches considered the excavation ground conditions and size, the different short- and long-term purposes of drives, and the future interactions with other excavations and the undercutting. Management of the strategies required implementation of new or modified data management systems, such as Deswik® and CaveCAD, to collate data acquired from face mapping, drive scanning, and scheduling into a system that could be easily monitored and rapidly modified when required. Strategies were planned into the monthly and weekly schedules using Deswik® for initial and remaining ground support. Remaining ground support maps with attributes of support elements assisted short- and mid-term planning for scheduling ground support remaining against the design. Face mapping, overbreak, and support damage levels were monitored as trigger points to ensure that the appropriate level of ground support was installed at the required time, changing the strategy when required through daily reviews. The management of geotechnical data and the implementation of ground support strategies have optimised the mining cycles while ensuring that the ground was supported appropriately at the required time. The strategies have increased development and support rates, improving schedule compliance.