Yang Zhiquan, Zhao Qinghao, Gan Jin, Zhang Jiajun, Chen Mao, Zhu Yingyan
Faculty of Public Safety and Emergency Management, Kunming University of Science and Technology, Kunming 650093, China; Key Laboratory of Geological Disaster Risk, Prevention and Control and Emergency Disaster Reduction of Ministry of Emergency Management of the People's Republic of China, Kunming 650093, China; Key Laboratory of Early Rapid Identification, Prevention and Control of Geological Diseases in Traffic Corridor of High Intensity Earthquake Mountainous Area of Yunnan Province, Kunming 650093, China.
Shennan Circuits Co., Ltd., Shenzhen 518000, China.
Sci Total Environ. 2024 Nov 10;950:175200. doi: 10.1016/j.scitotenv.2024.175200. Epub 2024 Aug 6.
Comprehensive studies on the freeze-thaw (F-T) damage mechanism in siliceous slates are lacking. In this study, we investigated the evolutionary characteristics of F-T damage in siliceous slates. To this end, scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and uniaxial compression tests were used to analyze the microstructure, phase composition, porosity, and macroscopic mechanical parameters of siliceous slate with varying initial water content during F-T cycles. The results revealed several insights. (1) The microstructure of siliceous slate undergoes significant change with respect to increasing water content and number of F-T cycles. The rock surface changed from smooth to rough, and the arrangement of the mineral particles changed from tight to loose. (2) More than 80 % of the contents of siliceous slate comprise oxygen, aluminum, silicon, potassium, and iron. In particular, siliceous slate comprises muscovite, quartz, clinochlore, and kaolinite. Both the clinochlore and kaolinite are unstable clay minerals. As clay minerals exhibit strong water absorption and expansion characteristics, kaolinite undergoes strong hydration reactions. Compared to rock samples without F-T cycles in the dry state, the clay mineral content of siliceous slate decreased by nearly 50 %, from 28.8 % to 15.5 %, after 30 F-T cycles in the saturated state. (3) The mechanical parameters of siliceous slates with varying water content decreased exponentially with the number of F-T cycles, while their porosity exhibited a positive correlation with the number of F-T cycles. The degree of deterioration in both increased with increasing water content. Both the number of F-T cycles and the initial water content were observed to wield a significant effect on the deterioration of siliceous slates. (4) The evolution curve of F-T load damage in siliceous slate exhibited characteristics of transitioning from gentle to concave and then to a convex stage of growth. Our results are expected to provide theoretical guidance for the evaluation and prevention of F-T disasters in cold regions.
目前缺乏对硅质板岩冻融（F-T）损伤机制的全面研究。在本研究中，我们调查了硅质板岩冻融损伤的演化特征。为此，利用扫描电子显微镜、X射线衍射、X射线荧光和单轴压缩试验，分析了在冻融循环过程中，初始含水量不同的硅质板岩的微观结构、相组成、孔隙率和宏观力学参数。结果揭示了几个要点。（1）硅质板岩的微观结构随着含水量和冻融循环次数的增加而发生显著变化。岩石表面由光滑变为粗糙，矿物颗粒的排列由紧密变为松散。（2）硅质板岩中80%以上的成分包括氧、铝、硅、钾和铁。特别是，硅质板岩包含白云母、石英、斜绿泥石和高岭石。斜绿泥石和高岭石都是不稳定的粘土矿物。由于粘土矿物具有很强的吸水性和膨胀特性，高岭石会发生强烈的水化反应。与干燥状态下未经冻融循环的岩石样品相比，饱和状态下经过30次冻融循环后，硅质板岩的粘土矿物含量从28.8%降至15.5%，减少了近50%。（3）不同含水量的硅质板岩的力学参数随冻融循环次数呈指数下降，而其孔隙率与冻融循环次数呈正相关。两者的劣化程度都随含水量的增加而增加。冻融循环次数和初始含水量都对硅质板岩的劣化有显著影响。（4）硅质板岩冻融荷载损伤的演化曲线呈现出从平缓到下凹再到上凸的生长阶段特征。我们的研究结果有望为寒冷地区冻融灾害的评估和预防提供理论指导。
