干湿循环作用下深部砂岩强度劣化及能量演化规律

为研究干湿循环对深部砂岩的强度劣化机制和能量演化规律，对经历不同干湿循环次数的砂岩进行基本物理参数的测定、单轴压缩试验和SEM观测，探讨砂岩单轴抗压强度劣化及单轴压缩过程中能量演化规律。试验结果表明：随干湿循环次数的增加，单轴抗压强度和弹性模量劣化效果明显，但平均劣化度逐渐减小，说明干湿循环对岩石的损伤劣化效果逐渐趋于稳定。干湿循环10次以后，砂岩在SEM下可以观测到明显的絮状物，单轴抗压强度降低明显，并呈现一定的延性特征。在单轴压缩试验中，随干湿循环次数的增加，砂岩试件中储存的弹性能逐渐减少，耗散能呈波动性下降。

Research on strength deterioration and energy evolution law of deep sandstone under dry-wet cycle

To investigate the strength deterioration mechanism and energy evolution law of deep sandstone under dry-wet cycle, the measure of basic physical parameters, uniaxial compression tests and SEM observations were carried out for deep sandstone specimens suffering various time of dry-wet cycles, then the deterioration of uniaxial compressive strength and energy evolution law during uniaxial compression were explored. Test results show that both uniaxial compressive strength of sandstone and elastic modulus deteriorate significantly with increasing the number of dry-wet cycles, but the average degree of deterioration decreases gradually which indicates that the deterioration effect induced by dry-wet cycle gradually comes to stability. After 10 dry-wet cycles, floccule can be watched obviously by SEM, and uniaxial compressive strength decreases significantly with a certain ductile feature. In uniaxial compression test, elastic energy stored in sandstone specimen reduces gradually with the increase of dry-wet cycles, and dissipation energy presents a fluctuant reduction.