A strength-stress coupling criterion for rockburst: Inspirations from 1114 rockburst cases in 197 underground rock projects

Rockburst is a kind of engineering geological disaster induced by artificial engineering excavation. Qualitative and quantitative statistical analysis of rockburst cases is the primary work and research basis for rockburst prediction and discrimination. In this study, 1114 rockburst cases are collected and the qualitative and quantitative characteristics are analyzed. It is found that rockburst is prone to occur in rocks that are hard, complete, dry, and unweathered. Strong rockburst occurs more frequently in rocks with high uniaxial compressive strength (σc), elastic modulus, and elastic energy index, and in rock masses with high initial maximum principal stress (σ1)and tangential stress. Notably, rockburst may occur only when σc≥ 60 MPa and σ1≥ 10 MPa. On this basis, the “Human–Rock–Environment” three-element mechanism of rockburst is presented. Guided by this conception, the rationality and defects of the traditional strength-stress ratio (SSR) criterion are investigated. The SSR criterion does not adequately consider the absolute difference between the rock strength and geostress, as well as their combined effects. Subsequently, a strength-stress coupling (SSC) criterion is proposed from a two-dimensional scale.This criterion is characterized by considering both the absolute boundary conditions of σcand σ1, as well as their coupling interval. Five intervals of weak, weak–moderate, moderate, moderate–strong, and strong rockburst are divided in the two-dimensional chart and their distinguishing conditions are given. The existence of two transition zones for weak–moderate and moderate–strong reflects the coupling effect of rock strength and geostress when rockburst occurs, confirming the rationality and scientificity of the SSC criterion. The verification results show that the SSC criterion features higher accuracy as compared with the SSR criterion.