Brittleness evaluation of coal based on statistical damage and energy evolution theory.

Abstract Coal brittleness is an important index for evaluating whether coal can be fractured effectively. Coal with high brittleness can form a large complex network after fracturing, and also has better productivity and ultimate recovery. Therefore, accurate evaluation of coal brittleness can provide theoretical guidance for well and layer selection of coal seam fracturing. In this paper, first, uniaxial compression experiments have been carried out. According to the measured stress-strain curves and the core failure form, the brittleness of different coal cores have been analyzed. Considering the damage evolution of coal in loading process, a theoretical evaluation model of coal brittleness has been established based on the statistical damage theory and the energy evolution law of rock failure process. Brittleness indexes of experimental coal cores have been calculated by this model, the calculated results were in good agreement with the experimental results, which proved that the theoretical analysis method of coal brittleness proposed in this paper can be used to analyze the applicability of coal seam fracturing. This paper presents an evaluation method of coal brittleness and establishes a relevant theoretical model. The research results of this study have important academic merits by filling in the blank of theoretical study on the brittleness of coal, and could also further facilitate the field operations of coal fracturing. Highlights • According to measured stress-strain curves and core failure form, the brittleness of different coal cores have been analyzed. • A new theoretical brittleness evaluation model of coal has been established. • Brittleness evaluation model of coal proposed in this paper can be used to analyze the applicability of coal seam fracturing. [ABSTRACT FROM AUTHOR]