Study on the sliding mechanism of the external dump slope in the open-pit mine with wind-blown sand base

Wind-blow sand (WBS) is widely distributed in the "Desert Gobi" region. This study is aimed at exploring the mechanism of how different thicknesses of the WBS layer influence the slope movement of external dumps in open-pit mines. To achieve this aim, the slope of the external dump in the open-pit mining area of Panel 3 in Daliuta Coal Mine was taken as the research object. First, similar simulation experiments were performed for investigating the failure modes and deformation characteristics of the external dump slopes under three geo-morphological conditions: loess base, 10-m-thick WBS base, and 20-m-thick WBS base, respectively. The following results were obtained from the experiments. For the slope with a loess base, its failure is mainly caused by circular sliding from the dump to the interior of the loess layer. For the slope with a 10-m-thick WBS base, the sliding mode involves circular sliding from the dump area to the interior of the WBS layer, linear sliding along the WBS base, and shearing along the foot of the dump area. For the slope with a 20-m-thick WBS base, the sliding mode is circular sliding from the dump area to the interior of the WBS layer. Besides, the sliding area of the dump slope expands as the WBS layer thickens. Furthermore, the results of similar simulation experiments were verified by the finite difference software FLAC3D based on the strength reduction method, and an equation of relationship between the safety factor of the dump slope with a WBS base and the thickness of the WBS layer was derived.