Effect of dynamic loading and tunnel support in deep-level mines.

Many rock falls in off-reef excavations in the South African mining industry occur because of failure on discontinuities within the rock mass. Among other reasons for their occurrence are insufficient support installation or incorrect assessment of rock mass conditions. Factors influencing blast performance and associated damage fall into four categories: geotechnical features such as rock strength and stress and the influence of stress-related and geological discontinuities; characteristics of the explosives used, including water resistance, shock energy and gas energy; design implementation and initiation accessories; and drilling accuracy. A field programme was carried out to investigate the influence of support units on the stability of roadways in fractured rock as seismic waves passed through. At one of the sites, the dynamic loading of a rock burst was simulated by detonating an explosive charge in the rock.
Many rock falls in off-reef excavations in the South African mining industry occur because of failure on discontinuities within the rock mass. Among other reasons for their occurrence are insufficient support installation or incorrect assessment of rock mass conditions. Factors influencing blast performance and associated damage fall into four categories: geotechnical features such as rock strength and stress and the influence of stress-related and geological discontinuities; characteristics of the explosives used, including water resistance, shock energy and gas energy; design implementation and initiation accessories; and drilling accuracy. A field programme was carried out to investigate the influence of support units on the stability of roadways in fractured rock as seismic waves passed through. At one of the sites, the dynamic loading of a rock burst was simulated by detonating an explosive charge in the rock.