Influence of wet–dry cycles on the disintegration characteristics of Cretaceous siltstone, China

Abstract

Cretaceous siltstone, which is widely distributed in the Yichang region, is a type of soft rock characterized by its low strength and its susceptibility to softening and disintegration when exposed to water. To gain a better understanding of the impact of wet–dry cycles on the disintegration characteristics and mechanisms of Cretaceous siltstone, a series of rock disintegration experiments were conducted. These experiments involved microscopic structure analysis and solution ion concentration tests on the specimens. The results of the experiments revealed that with an increase in the number of wet–dry cycles, the Cretaceous siltstone progressively fractured and disintegrated, with larger fragments transitioning into smaller ones. Microscopic structure analysis indicated that continuous wet–dry cycles altered the specimen's microscopic structure, resulting in the formation of new microcracks and pores. The results of solution ion concentration tests showed significant mineral dissolution losses during specimen immersion in the solution. Furthermore, a comparative analysis of various disintegration parameters highlighted that each metric emphasized specific aspects of Cretaceous siltstone disintegration characteristics. Therefore, adopting a multi-metric approach allows a comparison of the validation and assessment of the disintegration features of Cretaceous siltstone from many aspects. Finally, based on the experimental findings, a concise description and summary of the disintegration mechanisms of Cretaceous siltstone under wet–dry cycle conditions are provided; then, combined with its disintegration mechanisms, engineering prevention and control suggestions for timely drainage and a reduction in thermal contact are put forward from the perspectives of waterproofing and heat insulation, which can be used for reference.