Evaluating the Risk of Roof Fall in Phosphate Mines: Case Study of the Shanshuya Phosphate Mine in China

AbstractRoof fall in phosphate mines seriously endangers the safety of the mining activity. In this paper, the risk of roof fall occurring in phosphate mines is evaluated using the underground phosphate mine in Shanshuya, China, as an engineering background. The factors affecting roof fall in phosphate mines are analyzed, and an index system for evaluating the risk of roof fall in phosphate mine is established. Four evaluation models are employed to evaluate the risk of roof fall occurring: a set pair analysis model based on combination weights, a comprehensive fuzzy model based on hierarchical analysis, an approximately ideal ranking model based on entropy weight, and a gray relational analysis model. The evaluation results of the first two models are moderate risk with a bias toward intense risk. And the evaluation results of the last two models are slight risk with a bias toward moderate risk and moderate risk with a bias toward slight risk, respectively. The suitability of each of the evaluation models is analyzed which reveals that the evaluation results obtained using the different models are inconsistent. A combined evaluation method based on the four original evaluation models is subsequently proposed. Application of the combined evaluation method to the Shanshuya phosphate mine produces results that the roof fall risk is moderate with a bias toward slight risk. It is consistent with the actual situation in this phosphate mine. The results of the study can be used to provide technical support to engineers evaluating the risk of roof fall occurring in similar phosphate mines.