Experimental Study on the Troperty Degradation and Failure Mech- Anism of Weakly Cemented Sandstone Under Dry-wet Cycles
Experimental Study on the Troperty Degradation and Failure Mech- Anism of Weakly Cemented Sandstone Under Dry-wet Cycles
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DOI：
10.21203/rs.3.rs-389402/v1
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发表时间：
2021-04
影响因子：
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通讯作者：
Zhaoyang Song;Jie Tan;Zhiqiang Liu;Lihui Sun;Fangbo Ning
中科院分区：
文献类型：
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作者：
Zhaoyang Song;Jie Tan;Zhiqiang Liu;Lihui Sun;Fangbo Ning
以鄂尔多斯弱胶结砂岩为研究对象，探讨了不同干湿循环条件下弱胶结砂岩相对应力与声发射多参数之间的演化规律，建立了弱胶结砂岩干湿循环临界破坏识别模式。结果表明，随着干湿循环次数的增加，波速损失率逐渐增大。总的来说，纵波损失率大于横波损失率，说明纵波对弱胶结砂岩的降解更敏感。随着干湿循环次数的增加，断裂裂纹主要由主裂纹穿透破坏引起，二次裂纹明显减少。分形维数随干湿循环次数的增加而减小，在干湿循环次数为0时达到最大值，说明干湿循环次数为0时弱胶结砂岩的裂缝形态最为复杂。这一发现表明，干湿循环抑制裂缝的产生和扩展。在破裂之前，事件率似乎接近于0，然后平台振荡，然后突然增加。声发射b值在初始阶段相对较高，然后下降，这是初始损伤过程。弹塑性阶段再次上升，峰值阶段迅速下降，弱胶结砂岩发生失稳破坏。声发射熵值的变化与b值的变化规律正好相反。弱胶结砂岩在不同干湿循环下达到临界破坏状态时，相对应力值为95%。试验结果为弱胶结砂岩在干湿循环作用下的损伤演化机理和裂缝预测提供了新的方法和依据。
Taking the weakly cemented sandstone of Erdos, China, as the research object, the evolution law between the relative stress of weakly cemented sandstone and the multiparameters of the acoustic emission under different dry-wet cycles was explored, and the critical failure identification mode of weakly cemented sandstone under dry-wet cycles was established. The results show that as the number of dry-wet cycles increases, the wave velocity loss rate gradually increases. Overall, the longitudinal wave loss rate is larger than the shear wave loss rate, indicating that the longitudinal wave is more sensitive to the degradation of weakly cemented sandstone. With an increase in the number of dry-wet cycles, the fracture crack is mainly caused by the main crack penetration failure, and the secondary crack is significantly reduced. The fractal dimension decreases with an increase in the dry-wet cycles and reaches its maximum at 0 dry-wet cycles, which means that 0 dry-wet cycles witness the most complex morphology of fractures within the weakly cemented sandstone. This finding indicates that the dry-wet cycle inhibits the generation and expansion of fractures. The event rate appears to be close to 0 before the rupture, and then the platform oscillates, followed by a sudden increase. The acoustic emission b-value is relatively high during the initial stage and then decreases, which is the initial damage process. The elastoplastic phase rises again, the peak stage decreases rapidly, and the weakly cemented sandstone undergoes unstable damage. The change in the acoustic emission entropy value is exactly the opposite of the b-value change law. When the weakly cemented sandstone reaches the critical failure state under different dry-wet cycles, the relative stress value is 95%. The test results provide new methods and a basis for the damage evolution mechanism and fracture prediction of weakly cemented sandstone under dry-wet cycles.