Deformation prediction and analysis of underground mining during stacking of dry gangue in open-pit based on response surface methodology

Abstract

Deformation prediction and the analysis of underground goaf are important to the safe and efficient recovery of residual ore when shifting from open-pit mining to underground mining. To address the comprehensive problem of stability in the double mined-out area of the Tong-Lv-Shan (TLS) mine, which employed the dry stacked gangue technology, this paper applies the function fitting theory and a regression analysis method to screen the sensitive interval of four influencing factors based on single-factor experiments and the numerical simulation software FLAC^3D. The influencing factors of the TLS mine consist of the column thickness (d), gob area span (D), boundary pillar thickness (h) and height of tailing gangue (H). The fitting degree between the four factors and the displacement of the gob roof (W) is reasonable because the correlation coefficient (R²) is greater than 0.9701. After establishing 29 groups that satisfy the principles of Box-Behnken design (BBD), the dry gangue tailings process was re-simulated for the selected sensitive interval. Using a combination of an analysis of variance (ANOVA), regression equations and a significance analysis, the prediction results of the response surface methodology (RSM) show that the significant degree for the stability of the mined-out area for the factors satisfies the relationship of h>D>d>H. The importance of the four factors cannot be disregarded in a comparison of the prediction results of the engineering test stope in the TLS mine. By comparing the data of monitoring points and function prediction, the proposed method has shown promising results, and the prediction accuracy of RSM model is acceptable. The relative errors of the two test stopes are 1.67% and 3.85%, respectively, which yield satisfactory reliability and reference values for the mines.

Keywords

response surface methodology (RSM) / Box-Behnken design (BBD) / numerical simulation / boundary pillar / deformation prediction

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