(1) The rock mass in the slope is c

(1) The rock mass in the slope is classified intothree zones based on its geologic characteristics,spatial distribution and types of fractures: a zone oftensile fractures in the upper portion of the slope(Zone A), a zone of compression fractures in thelower portion close to the slope surface (Zone B)and a zone of shear fractures in the deep portion ofthe slope (Zone C). Zone B contains highlyfractured and weathered rock columns with crossjoints. The function of Zone B in determining theslope plays a key role in evaluating the overall slopedeformation as a result of long-term weathering.(2) The deformation and fracture mode of theslope can be generalized as a “sliding-tension”model, which is induced by the softening of the rockin the slope toe because of weathering. Specifically,the compression deformation of the slope toeresulted in the rock mass slip along the pre-existingjoints (i.e., f13), aggravated the deformation of therock mass in the lower portion of the slope andaccelerated the development and propagation of thecrack in the upper portion of the slope.(3) This analysis slope deformation and itsspatial and temporal correlations with rockweathering and river incision reveals the maintriggering factors that control the evolution of thestudied slope, which can be generalized as lope toesoftening effect. The softening effect of the slopetoe should be widespread, although the behavior and degree of this effect will differ because of thedifferences in the lithology, structure and riverincision history. However, the softening effect has along-term impact on the process of slope evolution.