Slope instability creates substantial hazards in open pits. It was observed that slope failures do not occur spontaneously, and rock mass does not move unless there is a change in forces acting on it. The common factors that lead to instability in open pits are removal of ground that provide support to the walls, increased pore pressure due to change in water level, blasting and earthquakes.

The following case studies are presented:

Open pit slope failure due to underground mining

Slope failure along geotechnical structures

Collapse of a highwall in an open pit

In these studies, the geotechnical modes of failure and precursors to instability were identified and analysed. The provided case studies confirmed that slope failure is preceded by various warning signs. Prior to major movement, measurable deformation, crack formation, ground movement and / or water inflow can be observed years to hours before major uncontrolled ground movement.