Abstract:

In this paper,the b-value of acoustic emission for the sample with "λ"-pattern cracks and the physical significance of the frequency-magnitude relation were experimentally and theoretically studied.The geometry of μλπ-pattern cracks influences the b-vnlue,and the b-value is very low.There are two kinds of processes of the b-value as a function of loading:one is that b decreases continuously and keeps low as loading level increases;the other is that b decreases and then rises or rises undulately.The change of b-value probably is closely related to the microfracturing processes.According to the physical picture of origination,propagation and coalescence of mierofractures,the distribution equation of microfractures was established.In the case without the interaction of cracks,the solution of the distribution equation is the Gutenberg and Richter relation.In the case of crack interaction,the solution of the distribution is not a simple power function,the frequency-magnitude relation deviates from linearity in logarithmic coordinates and it may be a precursor of large earthquakes.

摘要：

本文从实验上研究了"人"字式断层声发射b值并从理论上对频度—震级关系及b值变化的物理机理进行了探讨。"人"字式断层的引入使b值呈现低值,b值随载荷呈现单调下降以及下降又上升或波状上升两类变化,反映了不同的破裂过程。根据微破裂的产生、发展和聚合过程的物理图象,建立了微破裂的分布方程。在裂纹无相互作用时,分布方程的解即是Gutenberg-Richter公式。在裂纹相互作用时,分布方程的解不是简单的幂函数,在对数坐标中频度—震级关系偏离线性。