Influence of Adjacent Undercut Line Positions on Surrounding Rock Stability in Block Caving

Abstract In the block caving mining method, deformation and collapse can occur in roadways due to vertical stress concentration in front of the undercut line. Therefore to better understand this behavior, we establish a mechanical model of two neighboring solidly-supported and two neighboring simply-supported stepped bottom space structures based on the theory of elastic sheets. From this we derive an approximate analytical formula of the bending deflection function and an expression of the stress distribution using the Rayleigh-Ritz method. This mechanical model is applied to control the stability of surrounding rock near the undercut advancement line in the Pulang Copper Mine in China, and optimize the positional relationship between adjacent undercut advancement lines. Our results demonstrate that the larger the difference between adjacent undercut advancing lines, the less stable the undercut horizontal roadway becomes. Moreover, the smaller the spacing between adjacent undercut roadways, the lower the stability of the surrounding rock near the undercut advancing line. The results of this study provide theoretical support and methodology for undercut line planning in block caving.