“Assessments of Rock Fall and Joint Failure Risk in a Geologically Complex Section, South Cut 8 Area, DK2 Jwaneng Pit, Botswana,

Jwaneng Mine is one of the richest diamond mines in the world. This mine is the flagship of Debswana due to substantially higher dollar per carat obtained for its gems. Jwaneng Mine contributes about 60-70% of Debswana’s total revenue. Currently Jwaneng is mining at a depth of 452 metres and is expected to reach 816 metres by 2034. The Jwaneng kimberlites are emplaced in a thick sequence of shales, sandstones, and dolomites of Kalahari Formation, with thin occurrences of mudstones and siltstones in areas.
The Jwaneng Mine exploits a diamond bearing Kimberlite complex of three main pipes known as the DK2 Kimberlite. The mine is currently being expanded through the Cut 9 underground project. The deepening and widening of the pit have introduced complicated geotechnical issues, particularly on the southern side of the excavation. The steep rock slopes and the presence of primary & secondary discontinuities, such as joints, bedding planes, and faults, heighten the risk of rockfall and structural failure, are significantly threat to personnel safety, operational efficiency, and equipment integrity.
The present work aims a thorough and focused study of evaluation of potential rock failure modes in the Cut 8 South region and for developing effective monitoring and mitigation strategies to ensure safe mining operations. Data obtained through geological and structural mapping of the Cut 8 South side was used to identify key discontinuities, including joint sets, faults, and bedding planes. Kinematic analysis using stereographic projection was done to assess potential failure modes such as planar, wedge, and toppling failures. Further, slope stability modelling was done to simulate potential failure scenarios under existing conditions. Both DIPS and RS2 confirm that the wedge failures were common in areas with high joint density.
Controlled blasting methods were recommended to reduce the effects of vibration on joined rock masses. Another recommendation is the slope reinforcement through structural support via the targeted placement of shotcrete, wire mesh, and rock bolts in high-risk areas. Lastly the efficient water management is necessary to regulate pore pressures. Draining out thorough dewatering wells and horizontal drains must be set up.