Influence of the spatial variability of rock strength on the rock burst hazard in rock masses

The The reliability of existing criteria and methods for predicting the hazard of rock burst occurrence is currently assessed as insufficient. Not all of the deep and large-scale deposits that are characterized as rock burst prone and hazardous by the current regulatory guidelines are experiencing rock bursts. This paper focuses on critical examination of the rock burst hazard in the rock masses, rather than solely relying on individual rock samples. The article proposes a hypothesis concerning how the homogeneity of a rock mass influences its brittleness and the rock bursts, referencing foundational research that supports this concept. A thought experiment is presented to clarify how the homogeneity of a rock mass can directly influence its brittleness and the rock burst hazard. In order to systematically assess the homogeneity of a rock mass, the proposed methodology involves quantifying the coefficient of variation of strengths in a localized rock mass zone under uniaxial compression and tension. A comprehensive evaluation was conducted to explore the correlation between the rock burst hazard of a rock mass and the coefficient of variation for compressive and tensile strengths, drawing upon empirical data collected from 44 rock varieties across 18 distinct mining locations. The study is concluded by revealing a correlation between the rock burst of rock masses and the coefficient of variation. Suggested threshold values for the coefficient of variation are provided, indicating the rock burst hazard of rock mass in situ. Furthermore, the influences of various factors on the coefficient of variation and of rock burst hazard are examined.