The rockburst tendency evaluation in Jigongling phosphate mine

Abstract

[Objective] With the increasing depth of mining activities, rockburst has become a major hazard threatening the safety of underground engineering. To quickly assess the rockburst tendency in deep mines, a new evaluation method is proposed. [Methods] The method determines the in-situ stress direction by quantifying the unloading-induced damage characteristics of deep rock cores and measures the stress magnitude using deformation rate analysis(DRA). It further integrates other rock mechanical parameters to evaluate the rockburst tendency in the Jigongling Phosphate Mine in Guizhou Province. [Results] The research results indicate that:(1) the wave velocity and porosity of deep rock cores exhibit consistent orthogonal anisotropy due to unloading damage, thus determining the direction of horizontal principal stress;(2) DRA test result show that within the depth range of 728 m to 1 076.2 m, the minimum horizontal principal stress is 15.5~19.5 MPa, and the maximum horizontal principal stress is 21.1~25.6 MPa;(3) based on the elastic strain energy index(W_et), brittleness index(F), stress intensity ratio(R), and rock mass quality index(RQD) obtained from DRA tests, the rockburst tendency of deep rock masses was evaluated, showing a predominantly moderate tendency. [Conclusion] The proposed method can quickly and accurately measure in-situ stress and key parameters for rockburst evaluation during the early design stages of mine construction, providing important support for assessing rockburst tendency in deep mines.

Keywords

in-situ stress / rockburst / nuclear magnetic resonance(NMR) / deformation rate analysis / influencing factors / deformation