脆性岩石应力-应变全过程声学特征演化规律  

Evolution rule of acoustic characteristics of brittle rocks during whole stress-strain process

作　　者：张国凯[1,2] 李海波[2] 王明洋[1,3] 邓树新 王振[1] ZHANG Guokai;LI Haibo;WANG Mingyang;DENG Shuxin;WANG Zhen(School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China;State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences,Wuhan 430071, China;State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact, Army Engineering University of PLA, Nanjing 210007, China)

机构地区：[1]南京理工大学机械工程学院,江苏南京210094 [2]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [3]陆军工程大学爆炸冲击防灾减灾国家重点实验室,江苏南京210007

出　　处：《中南大学学报（自然科学版）》2019年第8期1971-1980,共10页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51809137,51608529);江苏省自然科学基金资助项目(BK20180480);中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室开放课题(Z017015)~~

摘　　要：采用岩石加载系统获得脆性花岗岩单轴压缩全应力-应变曲线,同步测试声发射(AE)和超声波变化,研究应力-应变全过程AE特征、声波波速、波速各向异性及透射波频谱特征随岩石破裂的变化规律,并结合宏观变形和声学特征综合分析花岗岩破裂过程。研究结果表明:破裂全过程AE频谱表现出双峰值或多峰值特征,主频及振幅先增后减;起裂应力附近AE主频快速增大,损伤应力后高频大幅值AE信号数量快速增多,对应中尺度裂纹扩展,同时AE频带宽度增大,峰值应力附近低频大幅值AE急剧释放对应大尺度破裂发生;波速先增后减,波速各向异性逐渐增大,峰后段波速降低幅度超过40%;透射波频谱振幅和主频随着微裂纹的压密闭合而逐渐增大,并伴随裂纹的萌生扩展逐渐减小,且频谱幅值变化比波速和频谱主频的大;大幅值AE震源在峰值应力附近局部聚集成核;AE数量显著增加早于波速下降及宏观扩容发生,AE事件对裂纹萌生、扩展的敏感性比波速和宏观变形的大,但峰后卸载段宏观变形对裂纹扩展的响应比AE事件对裂纹扩展的响应大,这与峰后破坏模式相关。The whole stress-strain curves of brittle granites were obtained under uniaxial compression by rock loading system, and the variation of acoustic emission(AE) and ultrasonic wave were measured synchronously. The variation of AE characteristics, wave velocity, anisotropy and spectral characteristics associated with the rock cracking were analyzed. Finally, rock fracture was comprehensively analyzed by combination of macro deformation and acoustic characteristics. The results show that the spectral curves of AE waveforms present in bimodal or multi-modal. The dominant frequency and amplitude of AE waveforms increase first and then decrease. The AE dominant frequency increases rapidly near the crack initiation stress. After the damage stress, the number of high-frequency and bigamplitude AEs induced by medium scale cracks increases rapidly, and AE bandwidth increases. The abrupt generation of low-frequency and large-amplitude AEs corresponds to large-scale ruptures prior to the peak stress. Wave velocity increases first and then decreases. The decreasing amplitude wave velocity reaches 40% at post-peak stage and velocity anisotropy increases. The amplitude and frequency of transmitted waves increase with the crack closure, and then decrease gradually with the initiation of cracks. The variation of spectral amplitude is much larger than that of wave velocity and dominant frequency. The coalescence of AE hypocenters with large amplitude occurs near the peak stress. The marked increase of AE event appears earlier than the velocity decline and rock dilatancy. AE event is more sensitive to the initiation and propagation of cracks than wave velocity and deformation. However, the response of macro deformation to crack propagation is bigger than that of AE event at the post-peak stage, which is associated with the failure mode.

关 键 词：脆性岩石 应力-应变全过程 声发射 频谱特征 波速 

分 类 号：TU451[建筑科学—岩土工程]