CHINA MINE ENGINEERING

This study takes the geologically complex Qingping Phosphorite Mine in western Sichuan as its engineering context and conducts systematic research on the precise inversion of the three-dimensional stress field and its spatiotemporal evolution mechanisms in deep heterogeneous rock masses under mining-induced conditions. Integrating field measurements via hydraulic fracturing, theoretical analysis, and numerical simulation, this research first employs data from three nearly orthogonal boreholes and introduces a Tikhonov regularization algorithm to improve the traditional least squares method, constructing a high-precision inversion model for the three-dimensional stress tensor that effectively overcomes the ill-posed nature of the inversion process. Subsequently, using the inverted in-situ stress field as the initial condition, the dynamic evolution patterns of the surrounding rock stress field, displacement field, and plastic zone during roadway excavation are revealed through theoretical elastic mechanics analysis and numerical simulation, while a quantitative assessment of rockburst risk is performed based on the tangential stress criterion. The results indicate that the mine’s stress field is dominated by near-horizontal NWW-SEE (N40° W ~ N50° W) tectonic stress, with the maximum principal stress reaching 26. 45 ~ 33. 64 MPa and a stress ratio (σ₁ / σ₃ ) of 1. 6 ~ 2. 0, exhibiting characteristics typical of a reverse fault stress regime. Mininginduced disturbances lead to significant stress redistribution in the surrounding rock, with a tangential stress concentration factor of 2. 0-2. 5 at the mid-height of the roadway ribs. The rockburst risk index (σθmax / σc) is 0. 47 ~ 0. 49, indicating a slight rockburst risk in both mining sections, and the plastic zone extends to 1. 8 ~ 2. 2 times the roadway radius. The systematic methodology of “geological prototype-field measurement-theoretical inversion-spatiotemporal prediction” established in this study enables a comprehensive analysis from static characterization to dynamic evolution of the deep stress field. The research outcomes provide critical scientific evidence and theoretical support for the optimized design and hazard prevention in deep mining engineering.