Novel Combined Mining Method: Calculation of Core Stope Structural Parameters

Abstract

With increasing mining depth, the mining methods for steeply inclined medium-thick ore bodies have become unsuitable. In this paper, by integrating the roof-pillar induced caving technology, through technical fusion and reconstruction, a combined mining method of roof-pillar induced caving and non-pillar sublevel caving has been formulated. The five core parameters of the combined mining method (the ultimate length of the temporary top pillar a₁, thickness h, maximum hanging length a₂, initial induced caving step distance L₁, and continuous induced caving step distance L₂) are crucial for ensuring the stability of the mining system structure. A novel method combining qualitative and quantitative approaches is proposed to calculate the five core parameters. Initially, a₁ is obtained through rock mass evaluation and the hydraulic radius inverse method. Subsequently, using Hu Haichang's thick plate theory, the relationship between the length and thickness of the thick plate is derived, and h and a₂ are calculated by combining different trial functions and boundary conditions. Finally, L₁ and L₂ are determined based on the mining process of the combined mining method and the calculated values of a₁, a₂, and h. Taking the 37# experimental stope at the +220 m level of the Daxin manganese mine as a background, the calculated core parameters a₁, h, a₂, L₁ and L₂ are 47, 12, 39, 8, and 4.5 m, respectively. These calculated parameters ensure safe mining operations. The proposed combined mining method and core parameters calculation method can provide a technological breakthrough for the mining of medium-depth ore bodies.