Deformation characteristics of slate slopes associated with morphology and creep

This study investigated the deformation characteristics of consequent slate slopes in the region between Cuifeng and Wuling in Taiwan. Onsite surveys, terrain analysis, and UDEC numerical models were used to describe the characteristics of gravity-driven deformation under various conditions and identify the process of slate deformation as well as potential failure mechanisms. Our results demonstrate that valley erosion and slope toe soaking mechanisms play key roles in the deformation of slate and accelerate the weakening of slate material. Comparisons of material strength of rock and foliation, the location of erosion gullies, and the inclination of the foliation indicate that a reduction in the strength of rock material and foliation expanded the range of slate deformation. The inclination of foliation is the most important factor in the deformation of slate and the location of erosion gullies has relatively little influence. Slate deformation was shown to begin in the tension zone at the cliff top, wherein the slope body slips along the highly inclined foliation, contributing to shear failure or composite failure near the eroded zone of weakness. The phenomenon of foliation opening was widespread within the area of deformation, enabling surface water and groundwater to seep in, thereby accelerating failure in the slate deformation zone.