The objective of this study was to examine the fracture evolution and related mechanism of silty mudstone in cyclic hydrothermal environments. Fracture evolution tests and computed tomography (CT) scans were carried out on silty mudstone specimens subjected to cyclic wetting-heating. The spatial–temporal variations of fracture parameters including the total length ratio, fracture rate, mean fracture width, fracture direction and fractal dimension were investigated. The mechanism underlying the fracture evolution in silty mudstone was also analyzed. The results show that fractures initiate and propagate from the wetting-heating surface down to the deep layer with increasing cycle number. Most of the fractures are parallel or perpendicular to each other and form a reticulate fracture network on every horizontal cross-section. The total length ratio, fracture rate, mean fracture width and fractal dimension considerably decrease as the depth increases, and the total length ratio and fracture rate significantly increase with increasing cycle number. After a wetting-heating cycle, only the zone within a depth of 14 mm shows slight fracturing; however, after 17 wetting-heating cycles, slight fracturing occurs within a depth of 104 mm. The fracture mechanism mainly involves the hydrothermal stress effect, water-softening effect, and mineral hydrolysis.

这项研究的目的是研究循环热液环境下粉质泥岩的裂缝演化及其相关机理。对经历了循环润湿加热的粉质泥岩标本进行了断裂演化测试和计算机断层扫描（CT）扫描。研究了断裂参数的时空变化，包括总长比，断裂速率，平均断裂宽度，断裂方向和分形维数。还分析了粉质泥岩中裂缝演化的机理。结果表明，随着循环次数的增加，裂缝从润湿加热表面开始并扩展到深层。大多数裂缝彼此平行或垂直，并在每个水平截面上形成网状裂缝网络。全长比 断裂速率，平均断裂宽度和分形维数随深度的增加而显着降低，总长径比和断裂率随循环次数的增加而显着增加。经过湿热循环后，只有14毫米深度的区域显示出轻微的破裂。但是，经过17个湿热循环之后，在104毫米的深度内发生了轻微的破裂。断裂机理主要涉及热应力作用，水软化作用和矿物水解作用。在104毫米的深度内会发生轻微破裂。断裂机理主要涉及热应力作用，水软化作用和矿物水解作用。在104毫米的深度内会发生轻微破裂。断裂机理主要涉及热应力作用，水软化作用和矿物水解作用。