岩石中的声发射和裂缝扩展（英文）

ACOUSTIC EMISSION AND CRACK DEVELOPMENT IN ROCKS@刘浩$香港合东中国育限公司

ACOUSTIC EMISSION AND CRACK DEVELOPMENT IN ROCKS

of PkD tbesis The research concentales mainly on the development of faiIure process in rock materials and the charateristics of associated acoustic emission through both laboratory and numerical investigations. Various asPectS are discussed in detail, and these include Kaiser effecL acoustic emission (AE) behaviour under uniaxial compression and tension, visualization of failure process and parametric stUdies using numerical approach. Laboratory testS have been carried out tO Study the Kaiser effect on severa tyPes of rock in Hong KOng. Recognizing that the AE counts are transient elastic waves due to local damages of rock, the quantitative relation betWeen AE countS and deformation of rock sPecimens has been established. Subsequently, an expression for Kaiser effect under uniaxial stress state is derived based on damage theory. The prediction of acoustic emission behaviour is found to be in good agreement with exPerimental results. TeChniques on servo controlled teSts on rock and acquisition of AE signals are also exPlored and discussed. Source location algorithms and techniques are aPplied to determine the AE sourees in tWo and threedimensional rock sPecimens. AcouStic emission behaviour of rock sPecimen under load has been scrUtinital by anaIysing AE parameters and AE sources in both comPression and tension. be charateristic stages of failure can be identified according to the featUI'e POints on the AE curves. For each Stag, micro-cracks which are reSPOnSible for the main sources of AE can be beed so that the process of crack formation, coalescence and development can be virtUally "visualized" step by step. Simultueously, numerical simulations are carried out in order to study the changes in stress and deformation distribution during the failure process. It provides new insigh on the fOrmation mechanism of failure zones and the development of cracks. Parametric stUdies are also conducted tO assess the effect of various factors on the failure process and failure mode.