Amount of fracturing inside rock slopes due to strength variation

Abstract

In rock slopes prone to topple, mechanical, physical, and/or chemical weathering might degrade the rock mass properties and compromise the stability of that rock slope. This paper investigates the effect of tensile strength degradation on the fracturing amount inside two rock slopes prone to topple. The first example is an ideal slope with one indipping joint set and the second one is an open pit mine from Canada. The simulation in this paper uses a discrete element model with Voronoi tessellation joint pattern to examine fracturing inside the rock mass due to the reduction of tensile strength, which simulates a weathering process. For the ideal slope, the fracturing amount was measured along the most possible rupture surface at different tensile strength values. While, the fracturing amount inside the open pit slopes was also traced along three different paths located near the most possible rupture surfaces as observed numerically. This study uses the ratio between the total length of fractures along or crossing a selected path and the entire length of the path itself and its called “Percent Fracturing”. The tensile strength of the rock mass was changed to show the effect of this variation the percent of fracturing. As show in the numerical model, amount of fracturing decreased as the tensile strength increased. This parametric study showed that the amount of fracturing rock slopes susceptible to toppling is highly influenced by the tensile strength values. The effect of friction and cohesion of intact material were not discussed in this paper.

Keywords: Chemical stability; Fracture; Open pit mining; Rock mechanics; Rocks; Slope stability; Tensile strength