Mechanism and dynamic process of landslide in Nanfen open-pit mine

Nanfen open-pit mine faces frequent landslides, debris flows, collapses, subsidence, and other geological disasters.In order to reveal the mechanism of the open-pit mine landslide and have a full understanding of its dynamic process, the landslide that occurred in the middle of the 394-502 m steps of the Nanfen open-pit mine on January 4, 2019, is taken as an example to study.In this work, on-site surveys, geological data, and numerical simulation are combined to study the open-pit mine landslides.The results show that excavation disturbance, freeze-thaw cycles, and blasting vibration are the main reasons to trigger the landslide of the open-pit mine.In addition, the landslide area is located in the area of the old landslide body, and the source of the landslide is composed of loose geomaterials.The low stability of the old landslide body itself is another important factor for the occurrence of the landslides.The smoothed particle hydrodynamics(SPH) method combined with the elastoplastic Mohr-Coulomb theory is used to simulate the whole dynamic process of the open-pit mine landslide.Numerical results show that the accumulation bodies of the open-pit mine landslide are distributed on the steps with a vertical drop of about 120 m.The landslide shape presents an inverted V shape, and the width of the lower edge of the landslide body is about 240 m.The shape, sliding distance, and scope of the open-pit mine landslide are in good agreement with the field survey results.The SPH method can reproduce the dynamic process of the open-pit mine landslide well.The numerical results can provide a basis for delimiting the dangerous areas of open-pit mines and formulating disaster prevention and mitigation measures.