Studies On Wave Velocity And Acoustic Emission Characteristics In Loading Process Of Rock

Rock is a typically inhomogenous brittle material which contains many natural weaknesses with various scales, such as microcracks, pores, and joints. Wave velocity would be change and large numbers of acoustic emission (AE) signals would be produced when rock suffer load till to failure. Because wave velocity change and AE signals are generated by propagating and expanding of microcracks inside rock, wave velocity change and each AE signal contains plentiful information of structure changing inside the rock. Therefore, investigation and analysis on wave velocity change and characteristics of these AE signals are very valuable for further knowing the damage development in the loading process of rock and forecasting rockburst in deep mine.In this research, wave velocity change and AE phenomenon in the loading process of different rock specimens were acquired by AE monitoring instrument. AE spatial distribution and AE rate change character in each stage of failure process of specimens were the focus of this research which mostly interests us. Some significant conclusions were achieved:(1) Wave velocity would explicit fall down after crack generated when rock up to 60%-80% load intensity in uniaxial loading process. Wave velocity of rock swells as load increase, debase as it reduce in cycle loading process. Wave velocity would rapidly fall down after macro-crack generated when rock up to 60%-70%, wave velocity of rock in low load (<80KN) above wave velocity of rock in high in the later cycles loading.(2) The relation between wave velocity and AE in loading process of rock, it could conclude two types:one is wave velocity explicitly reduces at the same time AE explicitly increase, another is wave velocity explicitly reduces time delay AE explicitly increase.(3) AE accumulative number reflects failure and deformation of rock specimens in definitive degree. The character of AE accumulative number could forecast crack generates and crack expansions of rock.(4)The distributing regularity of AE events in the failure process of rock specimens with various lithology was obtained. The spatial distribution of AE events well reflected the propagation and development of microcracks inside the specimens. The space distribution positon of AE events implicit the trend of macrocracks expansion, and predict the position of macrocracks. The result is very important for developing the research of forcasting rockburst.