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岩石的断裂韧度对于定量评价工程的安全及稳定具有重要意义,而岩石的破坏常常有水参与,在库水长期浸泡作用下,岩石的断裂力学特性将如何变化值得深入研究.基于此,以库岸边坡典型砂岩为研究对象,设计了长期浸泡试验,并基于断裂韧度、变形破坏特征和微观结构变化进行综合分析.试验结果表明:(1)浸泡作用下,砂岩的断裂韧度具有明显的劣化趋势,而且劣化幅度有一个先增大后减小的趋势,浸泡5~6月后,劣化趋势逐渐减缓;(2)砂岩三点弯曲试验的P-CMOD关系曲线可以比较明显地分成3个阶段:弹性阶段、屈服阶段、裂纹开展及破坏阶段,随着浸泡时间的增长,弹性阶段逐渐变短,屈服阶段逐渐变长,裂纹开展阶段曲线下降趋势逐渐变缓,而且达到开裂峰值荷载对应的切口张开位移逐渐增大,砂岩有逐渐“变软”趋势,脆性逐渐减弱,塑性逐渐增强;(3)浸泡作用导致的润滑、软化和砂岩内部微观结构的变化,特别是微观裂纹、裂隙的发展是导致砂岩断裂韧度及其他力学参数劣化的根本原因.研究成果对于把握库水长期浸泡作用下砂岩断裂力学特性具有比较重要的参考价值.
The fracture toughness of rock is of great significance for the quantitative evaluation of the safety and stability of the project. However, the rock failure is often accompanied by water. In the long-term immersion of the reservoir water, the fracture mechanics characteristics of the rock deserve further study. Based on this, The typical sandstones on the banks of the bank have been studied for a long time, and the long-term immersion tests have been designed and analyzed comprehensively based on the fracture toughness, deformation and damage characteristics and microstructure changes.The results show that: (1) The fracture toughness of sandstone has (2) The P-CMOD curve of the sandstone three-point bending test can be obviously divided into three stages With the increase of immersion time, the elastic phase becomes shorter and the yield phase becomes longer. The curve of the crack initiation phase decreases slowly and reaches the peak load of cracking The corresponding incision opening displacement gradually increases, the sandstone gradually “soften” trend, brittleness gradually weakened, plastic gradually increased; (3) soaking lubrication Softening and microstructure changes of sandstone, especially the development of microcracks and fractures are the fundamental causes of fracture toughness and other mechanical parameters of sandstone.The results of this study are of great importance for understanding the fracture mechanics characteristics of sandstone under long-term immersion Reference value.