Table 5 Impact of indicator factors on collapse disasters.
Indicator factors | Disaster impact |
|---|---|
Elevation | Elevation influences climatic conditions (such as rainfall) and the distribution of human activities. High-altitude areas are significantly affected by freeze-thaw cycles, leading to the development of fractures, while mid-altitud and low-altitude areas are more influenced by rainfall or human engineering activities. The collapse hazard level exhibits a zonal characteristic with changes in elevation. |
Slope | Slope gradient directly affects the relationship between gravitational driving forces and shear strength on a slope. Steep slopes (> 30°) have the highest incidence of collapses, moderate slopes (10°−30°) are more prone to landslides, while gentle slopes (< 10°) experience fewer slope-related disasters. |
Slope direction | Slope aspect determines the distribution of sunlight and rainfall, influencing weathering intensity and moisture accumulation. Northern slopes are more humid, with significant rock weathering, while southern slopes experience larger temperature variations, leading to pronounced freeze-thaw damage. Different slope aspects result in varying collapse patterns. |
NDVI | NDVI reflects vegetation coverage. Areas with high NDVI values have well-developed vegetation whose root systems stabilize the soil and reduce erosion, leading to higher slope stability. In contrast, areas with low NDVI values have sparse vegetation, exposed rock masses, and an increased collapse hazard. |
Distance from road | Road cutting and traffic vibrations can undermine slope stability. Areas closer to roads experience a higher frequency of collapses due to engineering disturbances, while areas farther from roads are relatively more stable. |
Distance from fault | Fault zones have fractured rock masses with low mechanical strength, making them prone to collapse induced by earthquakes and rainfall. The closer to the fault, the higher the collapse hazard. |
Distance from river | River scouring at the slope foot weakens the slope base, and concentrated surface runoff intensifies erosion. Areas closer to rivers have a significantly higher likelihood of collapse. |
Lithology | The effect of lithology on rock slope failure is mainly due to the different degree of weathering and shear strength of different rocks. Soft rocks are more susceptible to erosion and weathering, leading to slope instability, while hard rocks have a lower risk of collapse due to their higher compressive strength. |
Curvature | Curvature reflects the flow convergence patterns of the slope surface. Convex slopes (positive curvature) disperse water flow and have higher stability, while concave slopes (negative curvature) concentrate water flow, leading to moisture accumulation and significantly increased collapse hazard. |
