单轴压缩下砂岩破裂失稳时空演化特征研究

利用PCI-Ⅱ声发射监测系统和高速摄像仪对砂岩进行单轴压缩条件下声发射试验,通过声发射参数演化信息,分析砂岩变形各阶段声发射参数变化特征和失稳前兆情况,揭示砂岩微裂纹时空演化规律。试验结果表明:进入屈服阶段,大于80dB的高幅值声发射活动开始大量出现,各累积参数值在时序上出现突变拐点,呈指数上升趋势;声发射震级与能级之间存在近似线性关系,岩石内部高能级高震级事件的集中出现表征着岩石局部损伤劣化加剧,与高速摄像仪记录结果一致;屈服强度过后,其他破裂类型也开始逐渐增多,但能级大于4的声发射事件基本都是张拉破裂类型。上述特征现象均可以作为评价岩石破坏失稳的前兆信息。

Study on the characteristics of the spatial and temporal evolution of sandstone fracture under uniaxial compression

The real-time acoustic emission test of sandstone under uniaxial compression is carried out by using PCI-II AE monitoring system and high-speed camera. Combined with the information of AE parameters,the evolution characteristics of AE parameters with rock deformation are analyzed,from which the failure precursor information is identified. According to the AE characteristics, the temporal and spatial evolution pattern of micro-cracks is revealed. The experimental results show that the parameter values are abrupt at the yield strength, AE activity with high-level amplitude is appear; the concentrated occurrence of high-energy-level and high-magnitude events inside the rock is indicative of increased local damage degradation; and other types of rupture have also begun to increase, but most of AE events with energy level greater than 4 are almost tensile rupture types. The above characteristic phenomena can all be used as the precursor information of rock failure.