Experimental study on disintegration failure mechanism of weak mudstones under dry-wet cycling effect

Understanding the disintegration failure mechanism of weak mudstone in contact with water is essential for stability control of surrounding rocks in underground rock excavation. To investigate the disintegration mechanism and microstructural evolution of weak mudstone under dry-wet cycles, a comprehensive experimental scheme was designed and carried out in this paper. The standard slake-durability index I d2 of carbonaceous mudstone, sandy mudstone and siltstone are 49.3 %, 95.1 % and 98 % in slake-durability tests, respectively. The slake-durability index I di of the rocks exhibits a negative exponential relationship as the number of dry-wet cycles increases. The Weibull distribution function is observed to accurately depict the disintegration failure process of mudstone. The disintegration resistance of mudstones is discovered to be closely associated with its mineral composition and microscopic pore structure characteristics. The poorer the disintegration resistance of mudstone, the faster its disintegration rate under dry-wet cycles. The greater the variation in the grain size composition of disintegrated mudstone, the easier it is to reach equilibrium. Mudstone with more clay mineral content needs a greater number of dry-wet cycles to appropriately respond to its disintegration resistance.