Jwaneng Mine is an open pit located in Botswana. The eastern wall is characterized by quartzitic shale bedding planes that dip moderately into the pit slope, hence, posing a risk of planar sliding once undercut. The Bench 17 area, located on the eastern wall, hosts one of the two major life of open pit mine switch-backs access to kimberlite. Previous failures in the interim design have reduced the switch-back width, adversely impacting effective haul truck movement. Mine operations developed a plan that optimized switch-back width by installing a 32 m high geogrid reinforced rockfill retaining wall. A study of additional foundation supports was recommended to meet the design acceptability criterion for this area. This paper describes a numerical assessment of the support design.
Jwaneng Mine is located in south-central Botswana about 120 km west of the capital, Gaborone. Jwaneng, meaning "a place of small stones," is owned by Debswana, a partnership between De Beers and the government of Botswana. Jwaneng Mine is the richest diamond mine in the world by value. The eastern wall is characterized by quartzitic shale bedding planes that dip moderately into the pit slope, hence, posing a risk of planar sliding once undercut. The Bench 17 area, located on the eastern wall, hosts one of the two major life of open pit mine switch-backs access to kimberlite (see Figure 1). Previous failures in the interim design (Cut 8) have reduced the switch-back width, adversely impacting effective haul truck movement. Mine operations developed a plan that optimized switch-back width by installing a 32 m high geogrid reinforced rockfill retaining wall. A study of additional foundation support was recommended to meet the design acceptability criteria for this area. Different support options were assessed explicitly in order to meet the Design Acceptance Criteria (DAC). This paper describes the detailed numerical assessment of the support design using FLAC3D (Itasca, 2019). FLAC3D is a numerical modeling software for geotechnical analyses of soil, rock, groundwater, and ground support. Such analyses include engineering design, factor of safety prediction, research and testing, and back-analysis of failure.
