The Effects of Blast Damage Zone Thickness on Rock Slope Stability

Abstract

AbstractThe selection of blast damage zone T of the Hoek–Brown (HB) criterion is significant in open pit slope design and stability analysis. Traditional slope numerical analysis adopts a single value of blast damage factor D to the entire rock mass, which results in underestimation of slope stability. In this research, the parallel layer model (PLM), which rock mass is divided into a number of layers parallel to slope surface with a decreasing value of D applied to each layer in slope modeling, is used in the limit equilibrium method to investigate the effect of blast damage zone T on the stability of rock slopes. Based on extensive parametric studies, a blast damage zone weighting factor fT is proposed to quantify the influence of T on the evaluation of the factor of safety (FOS) of given slopes. Results show that the selection of T in the slope model plays an important role in terms of calculation of FOS, especially, when the ratio of T to slope height H is less than 1.0. Finally, based on fT and the existing stability charts, a stability model is proposed for estimating the FOS of slopes with various slope geometries and rock mass properties. The reliability of the proposed stability model is tested against numerical solutions. The results show that FOS estimated from the proposed stability model exhibits only 5.6% average discrepancy from numerical solutions using 1254 sets of data. The proposed stability model is simple and straightforward, and can be used for the preliminary rock slope stability analysis considering blast damage zone effects.