A New Rock Brittleness Evaluation Method Based on the Complete Stress-Strain Curve

Abstract Brittleness is a crucial parameter of rock mass and the key indicator in engineerings, such as rockburst prediction, tunnelling machine borehole drilling, hydraulic fracturing. To solve problem using present brittleness indexes, existing indexes were firstly summarised this paper. Then, index (BL), which considers ratio stress drop rate increase peak stress, was proposed. This new has advantage simplifying acquisition parameters avoiding dimensional problems, well taking complete stress-strain curves into account. While applying BL, strain used to describe difficulty brittle failure before point, can reflect without dimension problem. In order verify applicability through PFC2D, microparameters confining pressure changed model different types numerical specimens condition. The results show that BL classify characteristics characterise constraint on brittleness. Moreover, influence microparameter macroparameter studied. further reliability study conducted uniaxial triaxial compression tests (30 MPa) marble, sandstone, limestone, granite under pressure.