Fuzzy fault tree analysis for coal burst occurrence probability in underground coal mining

Coal burst is one of the hazardous events that mining engineers have been struggling with it since past decades. This phenomenon has sudden and violent nature and almost occurs without warning. In coal burst events, a high volume of coal pieces ejected violently into the working space. Consequently, coal burst can lead to casualties and severe damages. The interaction between causing factors of coal burst can lead to different triggering mechanisms. In this paper, coal burst was classified based its mechanisms into self-initiated and remotely triggered. Due to the sever coal burst consequences, its occurrence probability analysis is very essential. In this study, combination of fuzzy theory and fault tree analysis have been used for coal burst occurrence probability analysis. Therefore, occurrence of coal burst as a top event in fault tree has been analyzed using fuzzy fault tree analysis. According to the results, occurrence probability values of coal burst with self-initiated and remotely triggered mechanisms are 0.9% and 11.6%, respectively in coal mines. In addition, the critical paths that lead to coal burst are indicated in this study. These paths are composed of important causing factors that known as basic events in fault tree. Therefore, high mining depth along with local mine stiffness lower than coal stiffness make a more critical path for self-initiated coal burst; and the seismic energy release due to the slippage of discontinuities nearby the coal mines make also a more critical path for remotely triggered coal burst. The result can be inspiring for mining engineers which have conflicted with coal burst.