Mathematical evaluation on the applicability of bolter miners based on variable weight fuzzy theory

With remote automatic control and ground control, bolter miners have the significant technical advantages of digging-bolting-drilling, full width cutting, driving-bolting synchronization, bolting-transporting parallel, multi-anchor balance and so on, and can meet the driving requirement of 100 meters per day, which has become a key equipment group for the coal industry to realize high-level intelligent and efficient excavation and alleviate the linkage of drivage and mining during the “14th Five-Year Plan”. However, the application in dozens of mining areas in recent 5 years shows that bolter miners have certain applicability requirements for the geological conditions of coal seam driving, compared with the traditional cantilever roadheader, the efficiency and economy improvement is not obvious. Therefore, it is urgent to evaluate the applicability of bolter miners. This paper puts forward a method for combining AHP (analytic hierarchy process), fuzzy mathematics and variable weight theory, and constructs a multi-level impact index system for the applicability evaluation of bolter miners based on the practical experience in various mines. The index system is composed of four indicators, such as coal seam geological occurrence characteristics, roadway characteristics, geological structure characteristics and safety impact factors. The 21 sub-indicators and its value conditions are determined, and four judgment subsets are established to characterize the applicability degree (“poor, medium, good and extremly good”). The judgment matrix and constant weight of sub-indicators are obtained by AHP, and the fuzzy relationship matrix of sub-indicators is established by fuzzy mathematics membership function. The logarithmic function and the Hadamard matrix principle are introduced to realize the variable weight of constant weight (lowering the weight of “good” factor and raising the weight of "bad" factor to make it more practical). After two comprehensive evaluations, the final evaluation result value is obtained and its applicability is selected according to the maximum membership principle. Therefore, a complete variable weight fuzzy hierarchical comprehensive evaluation model is created. Finally, three mine parameters (abbreviated as HB mine, HL mine and XZ mine) with different conditions that have been applied to the bolter miner are introduced to verify the rationality of the model results. The results show that although the conditions of the three mines are quite different, the evaluation results can well reflect the performance and membership degree of the indexes of each mine under different comment sets, which is very consistent with the effect of field practice. The calculation models of weight assignment, matrix composition and variable weight method in the comprehensive evaluation model are close to the actual situation, the variable weight fuzzy hierarchy comprehensive evaluation model quantifies the applicability of the bolter miners to the geological conditions of the coal mine, which is helpful for the mine to make decision in advance.