Deformation and failure mechanism of a mining slope under mining blasting and rainfall

Abstract

Landslides occur frequently in mining slopes under rainfall, and to effectively reveal their complex disaster mechanisms, the synergistic effects among the triggering factors must be considered. This study takes the landslide disaster in Pusa, Guizhou as an example, and uses the rod explosion source, the Landau explosion model, and the fissure network seepage model in the continuous-discontinuous software (GDEM) to construct the numerical model of the overlying rock combinations and the engineering geological model. The deformation process of slopes under multiple factors (mining-blasting-rainfall), reveals the deformation mechanism of slopes from the stable state, critical state to unstable state. The results indicate that blasting can quickly add the fissures of the nearby rock masses, the damage mainly occurs in the first 20ms, and the damage range of the rock masses is limited and can be divided into crushed, fissured and vibrating zones; the goaf cause stress redistribution on the slope, thus mining contributes significantly to the overall deformation and large fissures of the slope; rainfall infiltrates along the developed fissures, increasing the saturation and fissure water pressure distribution range to the interior of the slope. The deformation process of slopes can be summarized into five stages, with the mechanism summarized as excavating-subsidence-tension-dumping-sliding. The research results involve multiple triggering factors, not only breaking through the limitations of single-factor analysis, but also revealing the complex causal mechanism of disasters, which can provide a better reference value for the prevention and control of mining slope disasters.