Processes and behaviors of block topple avalanches resulting from carbonate slope failures due to underground mining

Major rock landslides are the main type of geological hazards in the mountainous areas of southwestern China, in which failure modes and behaviors are compounded. In this study, field surveys, centrifuge modelling, and numerical simulations were utilized to analyze the failure process of a steep-dip and layered carbonate slope which was induced by underground goaf. These included gravitational bending, interlayer faulting, topple failure of the upper blocks due to underground mining, shearing through the underlying slide-resistant rocks, and catastrophic avalanches. It was concluded that the bending and compaction of the weak interbedded coal seam had occurred on the slope with the effects of gravity. The support for the overburden rocks was lost following the underground mining activities, which led to bedding separation and the generation of cracks. The upper blocks acted on blocks at the toe, and shear failure at the toe was initiated when the force along the joints exceeded the anti-shear strength, which gradually formed an intact failure surface. Then, a rock slide took place which transformed into a catastrophic rock avalanche. The failure process was validated using a FLAC3D simulation and centrifuge testing.