Study of evolution law of cracking for swelling mudstone of Sichuan central Redbeds in hydration process

抄録

Several cracking test of swelling mudstone of Sichuan Central Redbeds are conducted on the condition of hydration. Based on tests result, the process of crack development in mudstone, its influencing factors and cracking mechanism are analysied. The results show: (1) the cracking process can be divided into three stages: moisture absorption and crack generation, crack development and rapid expansion, and stablization. Initial water content is negative correlation with cracking degree, and soaking water absorption has a greater cracking degree than capillary water absorption. Influenced by the content of clay minerals, the overall cracking degree of mudstone is larger than that of argillaceous sandstone. (2) In the process of moisture absorption, the swelling deformation of mudstone is uneven, and this uneven expansion also changes with time. (3) The cracking of swelling mudstone is caused by uneven swelling and softening effect. The uneven swelling of mudstone is caused by: i) The spatial distribution of clay minerals is not uniform; ii) The whole process of moisture absorption is not uniform in space; iii) There are visible or invisible initial cracks inside the swelling mudstone.