Evaluation of vertical shaft stability in underground mines: comparison of three weight methods with uncertainty theory

Abstract

Shaft stability evaluation (SSE) is one of the most crucial and important tasks in view of the role of vertical shaft in mining engineering, the accuracy of which determines the safety of on-site workers and the production rate of target mine largely. Existing artificial methods are limited to the amount of data and complex process of modeling as well as rare consideration of comprehensive evaluation model in this field. In this way, this paper introduces a high-efficient model that incorporating the unascertained measurement (UM) and multiple weights (the analysis hierarchy process, entropy and the criteria importance through intercriteria correlation) to meet the engineering requirements. Simultaneously, the main parameters, including surface subsidence velocity, cumulative surface subsidence(CSS), loose strata thickness(LST), the water level drop in aquifer (WLD), shaft wall thickness, construction methods and shaft wall types, and diameter ratio of shaft and shaft lining quality, are prepared to analyze the shaft stability. Linear and nonlinear membership functions are utilized to investigate the index correlation belonging to different risk levels. The stability class is determined through the index measurement vectors and classic classification criteria considering the individual index importance. The confusion matrix-based results show that the ensemble model with optimal structure has inspired performance in SSE with 100% accuracy. Furthermore, the shaft is sensitive to the factors CSS, LST and WLD using the sensitivity analysis. Additionally, some parameters associated with the shaft stability are investigated from Daye Iron mine (China) to validate the applicability of target model, the results of which are consistent to the on-site conditions perfectly. Findings reveal that the constructed model has great potential in assessing the shaft stability, which is beneficial to eliminate the risk of shaft failure in time.