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超声波波速变化是判定岩体裂纹扩展、损伤演化的重要手段。联合单轴压缩与超声波波速测试试验,探索了加载过程中砂岩试样的波速变化特征,并据此对砂岩的破裂发展及损伤程度开展了评价。结果表明,在压密和弹性阶段内,砂岩的波速和动弹性模量都呈增大趋势,表明砂岩结构随加载变得更加致密;而随加载进行由弹性阶段逐渐进入塑性阶段,波速和动弹性模量均开始下降;横波、纵波波速的转折点基本对应压密—弹性、弹性—塑形的转折点,而波速比的变化较符合岩心内部裂隙发展特征;对比发现,横波波速变化比纵波波速敏感性更大;在整个加载过程中,岩石的动弹性模量与应力应变曲线都呈现良好对应关系,表现为弹性阶段后期动弹性模量开始下降,而进入塑性阶段后,动弹性模量下降速率渐趋于最大值。该研究可为砂岩内部损伤演化规律及灾变预报预警等有益参考。
Ultrasonic wave velocity change is an important means to determine the crack propagation and damage evolution of rock masses. Combined with uniaxial compression and ultrasonic wave velocity tests, the variation characteristics of the velocity of sandstone samples during loading were explored, and the development and damage degree of sandstone were evaluated. The results show that the sand velocity and dynamic elastic modulus of sandstone all show an increasing trend during compaction and elastic stage, indicating that the sandstone structure becomes more dense with loading. When the loading progresses from the elastic stage to the plastic stage, Elastic modulus and elastic modulus all began to decline. The turning points of shear wave and longitudinal wave velocity basically corresponded to the turning point of compaction-elasticity and elastic-shaping, while the change of wave velocity ratio was more in line with the development characteristics of core fissures. Comparing the changes of shear wave velocity and longitudinal wave velocity In the whole loading process, the dynamic elastic modulus of rock shows a good correspondence with the stress-strain curve. The dynamic elastic modulus of the rock begins to decline at the late stage of elastic stage, and after entering the plastic stage, the rate of decline of dynamic elastic modulus Getting to the maximum. The study can be sandstone internal damage evolution and disaster prediction and early warning and other useful reference.