Quantitative risk assessment and dimension optimization of stopes under anchor cable support using logistic regression and numerical simulation

The roof’s safety and the stope’s production capacity are mutually constrained. A method of stability assessment and span optimization of underground stopes is proposed under the anchor cable support condition through logistic regression, numerical simulation, and industrial test. Logistic regression is utilized to plot the stability probability contours graph under support conditions, quantifying the probability of stope stability. The stope size determined by the design boundary under support conditions in the Matthews stability graph corresponds to about 60% stability probability, with high instability risk. A numerical model is developed to optimize the stope span, considering thrust faults. Simulation results demonstrate that thrust faults have dual effects: promoting or inhibiting rock mass deformation on either side. The cable support system is more effective for poor rock mass, reducing displacement by up to 30.74%. Its effectiveness decreases with increasing span, reducing to 7.19% at a span of 24 m. The roof stability probability with the ultimate stope span from the numerical model considering thrust faults exceeds 85%. The on-site monitoring displacement distribution character aligns with numerical simulation. The roof maintains stability throughout the stope mining cycle. The reliability of the numerical model and stability probability contours graph was verified in engineering tests. This study serves as a reference for addressing analogous challenges in other mining operations.