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The preevaluation to the vulnerability of the surrounding rocks is proposed as one of the reliable indicators of the safety coefficient of gateway support and a foundation to optimize the support design parameters. In this study, taking the surrounding rocks, stress, geological environment, and service time into consideration, the safety coefficient is determined based on the vulnerability scores calculated by the vulnerability preevaluation model of the surrounding rock. Applying the safety coefficient to the instability evaluation of the composite rock-bolt bearing structure, the strength required to maintain the stability of the gateway is calculated, which further provides references and guidance to the optimization of the anchor support parameters. This method has been successfully adopted by the GuCheng coal mining project in N1303 tailgate to strengthen the anchor-bolt structure in the roof watering area especially the main inclined shaft. Applying more accurately calculated strength to the anchor-bolt structure can effectively avoid the issue of overcompensation, thus reducing the cost and increasing the driving speed. Furthermore, this method provides insights into optimizing design parameters of the gateway. This method provides a reliable basis for the optimization design of bolt support parameters in coal mine gateway. [ABSTRACT FROM AUTHOR]

The burial depth and dip angle of a coal seam, the size of the working face, mining height, structure of the overlying strata, coal mining method, and the number of mining slices all significantly affect the amount of water flowing in a fractured zone. Combined with these seven factors, a predictive model for the height of water flowing in a fractured zone was established based on a fuzzy neural network, and 49 typical cases were chosen to train and test the network. The test error of the network was small and the match degree was high. Furthermore, the predicted height of water flowing in a fractured zone of working face 2309 in the Guozhuang coal mine, China was found to be within the range of the results calculated by more traditional (the empirical formula, the key stratum, and numerical simulation) predictive methods. After a safety coefficient of 1.2-1.5 was incorporated, a 183-211 m thick coal/rock safety pillar was required. In addition, a 98 m rock pillar with original permeability was left between the protective layer and the weathered zone. Therefore, under normal conditions, the mining of working face 2309 beneath Jianghe River was assessed to be safe and feasible. [ABSTRACT FROM AUTHOR]