Study on disaster-prone geological structure and instability mode of typical goaf landslide in Southwest mountainous area

Abstract: [Objective] Landslides occur frequently in the goaf areas of the mountainous regions in southwest China. The purpose of this study is to explore the commonalities and differences among such landslides, so as to formulate scientific disaster prevention and mitigation countermeasures. [Methods] This article takes the Jiguanling landslide in the limestone area, the Zhaojiagou landslide in the clastic rock area and the Shanyang landslide in the metamorphic rock area as the research objects for a comparative study. It adopts methods such as data collection and analysis, on-site investigation, multi-phase remote sensing interpretation, physical and mechanical tests of rock and soil masses and numerical simulation to analyze the similarities and differences in the disaster-prone geological structure and instability mechanism of the research objects.[Results] The research results show that when the slope has features such as steep terrain, good open-air conditions and binary structure, landslide disasters are prone to occur. The numerical simulation results indicate that under the goaf condition, the displacement of each landslide increases, the maximum shear strain increment is concentrated in the potential sliding surface and the roof area of the goaf, and the overall stability of each landslide decreases. [Conclusion] The limestone mountainous area is characterized by thick layers of hard rock interbedded with thin layers of soft rock, presenting high-intensity rock mass characteristics. The Jiguanling landslide belongs to the toppling - sliding failure mode type. The clastic rock mountainous area is affected by the interbedded structure of thin-layer fragmented soft and hard rocks, and the overall strength of the rock mass is weakened. The Zhaojiagou landslide belongs to the type of creep - tensile fracture failure mode. The metamorphic rock mountainous area presents a structure of hard rock at the top and soft rock at the bottom, with significant differences in strength. The Shanyang landslide belongs to the type of slipping-collapse failure mode. [Significance] This article provides an important scientific basis for the early identification and disaster formation pattern research of landslides in goaf areas.