Instability analysis of jointed rock slope subject to rainfall using DEM strength reduction technique

Uncertain climatic factors like rainfall can induce the complex hydro-chemo mechanical processes within the rock mass, and thus substantially increase the failure probability of rock slope. This paper presents a numerical investigation into the rainfall-induced instability mechanism of jointed rock slope with two joint inclinations of dipping 45 degrees and 60 degrees and the corresponded safety factor using the two-dimensional Distinct Element Method (DEM), where the non-uniform strength reduction approach is employed. For this purpose, some crucial aspects were mainly discussed, i.e. the quantifications of water softening and chemical weathering effects in the micro bond contact model, the necessary fitted functional relationships used in the safety factor, and determinations on the intensities of water softening and chemical weathering. The results show that the proposed DEM strength reduction provides a feasible approach to analyze the rainfall-triggered instability of jointed rock slope. The significant rise of bond breakage and the accompanied large displacement of sliding block indicate the achieved critical infiltration depth of rainfall and the consequent destabilization of jointed rock slope. The jointed rock slope with steeper dipping joints has lower safety factor, and thus is more prone to instability under the same rainfall effect.