Study on the Disintegration Resistance of Different Types of Schist on the Eastern Slope of the Tongman Open-Pit Mine

This study aimed to investigate the disintegration resistance of schist on the eastern slope of the Tongman open-pit mine. It examined the effects of cycle number and mineral composition on the disintegration resistance indexes of four types of schist through thin section identification and laboratory disintegration resistance tests. Furthermore, we analyzed the morphological characteristics of the disintegration residues using laboratory tests. Based on pore micro-damage theory, the mechanisms responsible for the differences in disintegration resistance among the four types of schist were further explored. The results show a negative correlation between the disintegration resistance index and the number of cycles. For the same number of cycles, the disintegration resistance indices for the four schist types were ranked as follows: greenish-gray chlorite-bearing muscovite schist > gray weakly chloritized biotite–muscovite schist > greenish-gray muscovite schist > gray muscovite schist. The disintegration residues of schist samples were categorized into four morphological patterns: thin sheet-like, moderately thick sheet-like, blocky, and granular. These patterns were then thoroughly elucidated. The differences in the disintegration resistance characteristics of schist were closely related to their material composition. The microstructural pore damage within the rock is the essential factor causing schist disintegration. Variations in rock porosity led to differing damage factors, which explain the distinct disintegration resistance characteristics observed across the four types of schist. The proposed preventive measures, developed through a systematic analysis of schist disintegration mechanisms, provide an effective framework for slope stability management. This research offers valuable insights into the weathering characteristics of rock masses in slope engineering, which is significant for understanding the progressive failure modes of disintegrating metamorphic formations.