Application of a rock buttress to design of slopes at Cassiar Mine

CIM Bulletin, Vol. 79, No. 896, 1986

DENNIS C. MARTIN, Piteau Associates Engineering Ltd., West Vancouver, British Columbia and TIM J. CAREW, Cassiar Mining Corporation, Cassiar, British Columbia

One approach to stabilization of rock slopes is to place a buttress at the toe of the slope to provide addtional resisting forces and increase the length and strength properties along the failure surface. This paper describes the rock mechanics and mine planning aspects of incorporating a buttress of intact rock in the lower part of the slope as part of the slope design for the south wall of the final pit at Cassiar Mine. "Stability analysis techniques and results are described. Analyses results have indicated that, in order to maintain steep over-all slopes in the final pit, a buttress of intact rockshoud be incorporated into the lower section of the slope until late in mine life. The effect of the buttress is to flatten the slope and reduce the slope height thereby improving slope stability. The mining plans would be such that the buttress would be mined out during the last four months of mining, when the consequences of instability would be least severe.

Keywords: Rock mechanics, Slope design, Buttress, Mine planning, Stability analysis techniques, Slope stability, Cassiar Mine.