Rockfall Hazards Mitigation
Defination: Rockfall refers to quantities of rock falling freely (uncontrolled) from a natural slope or man-made excavation. The term is also a synonym for collapse of rock from an underground mine roof or open pit mine high-wall, also known as fall of ground. Rockfall is also major hazard in excavations for highways and railways in mountainous terrain. A rockfall event is generally initiated by climatic and biological event that causes a change in the forces acting on a rock. In a mining environment, rockfall usually occur due to blasting induced vibration.
Rockfall protection systems refers to the structural elements used for the mitigation of the potential hazards resulting from un-controlled falls of ground.
Rockfall in general range from minor falls to larger falls that affect safety of people and may also cause damage to infrastructure. Rockfall may also include substantial slope failures that cause serious damage to critical public and private infrastructure.
The effect of rockfall events range from a simple damage to private property, injury or loss of live. It may also lead to disruption of critical economic systems such as closure of a mine or critical road access. In a mining industry rockfall can have a detrimental effect on the safety and economic position of the mining operations.
A rockfall event may be the result of factors both internal and external to the rock slope combined with the action of gravity. The external factors are chemical changes in the rock surface, temperature variations, surface scour by water and wind action, forces exerted by plant roots, and blasting/excavation methods. The internal factors are connected with residual geological stresses in the rock and with fractures or discontinuities. Of all the foregoing factors the one which has the greatest effect is undoubtedly the action of water and the freeze/thaw cycles.
Rockfall hazards mitigation systems aims at minimising the potential effects of rockfall events through the design and installation of rockfall protection systems. Rockfall protection systems are engineered to be durable, effective and to save lives.
Prepared by
Ernest Rankhododo (MSc. Eng.)
