SkyGeo technical paper cover showing a landform and survey drone, illustrating how InSAR complements drone surveys for detailed ground deformation monitoring.

Stabilisation of open pit wall movements detected by InSAR using horizontal drains

Technical Paper

This paper details the successful mitigation of slope instability at the M15 west slope of the Main Pit at First Quantum Minerals' Kansanshi copper mine in Zambia.

 

  • SkyGeo's InSAR monitoring service used high-resolution TerraSAR-X imagery to identify a circular subsidence pattern on the M15 west slope, suggesting a complex failure mechanism.

  • The intervention, consisting of depressurisation drilling and horizontal drains starting in November 2022, successfully reduced the slope's displacement rate from -101 mm/year to -53.4 mm/year.

  • InSAR provided continuous, long-term pre-warning of movement that reactivated during the wet season, enabling Kansanshi Mine to plan crest unloading to ensure stability.

  • Timely InSAR intervention allowed for the safe and continued operation of trolley lines and successfully avoided other costs associated with a slope failure, such as increased tramming distance.

Frequently Asked Questions

  • Pit slope engineers, geotechnical managers and mine planners dealing with wall movement, especially movement that gets worse in the wet season.

  • How InSAR monitoring with TerraSAR-X detected instability on the M15 west slope of the Main Pit at First Quantum Minerals’ Kansanshi copper mine in Zambia, and then measured how well drainage worked.

  • A circular pattern of subsidence on the slope, which pointed to a complex failure mechanism.