Stability of coarse mine waste dumps

A dissertation submitted to the faculty of engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment for the degree of master of science in engineering JULY, 1984It is economically desirable to build dumps of coarse mine waste as high a, possible. A review of available literature indicated that a significant decrease in the strength of coarse material occurs at high stress levels. A literature survey was conducted to establish possible dump failure modes and methods of slope stability analysis appropriate to dumps. Consolidated, drained triaxial tests on several mine waste materials have shown that above a normal stress of 1600 kPa, slight curvature of the Mohr strength envelope occurs. However, sample stability analyses show that there is little or no difference in factors of safety for typical dump slopes, obtained by using a constant average friction angle, or by using variable friction angles derived from a power equation which describes the curved strength envelope. Thus it is concluded that the curvature of the strength envelope, has little influence on the factor of safety of dump slopes