Statistics of microcracks in heterogeneous materials (granites)

Abstract

The amplitude distributions of acoustic emission signals from granites under compressive stresses are expanded into a power series of gamma functions. It is established that the mean amplitude of each term in the expansion falls in the range of acoustic emission signals corresponding to the hierarchical levels of the crack formation in loaded granites. On this basis, a model of crack formation is proposed according to which the size distribution of microcracks in granites under load rapidly attains a thermodynamically optimum form for each hierarchical level of crack formation. The results of calculating the mean sizes and evolution of microcracks at each hierarchical level are in good agreement with the experimental data.