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Electronic detonators not only improve delay accuracy and the flexibility of initiation network design, but also realize the full lifecycle safety control of detonators from production to transportation, storage, and blasting operation. Therefore, electronic detonators are the key development direction of the civil explosive industry. This study summarized the development status of the electronic detonator initiation technology from the aspects of electronic detonators' structure, application scenarios, intelligent level, blasting design theory, and failure mechanism. Our study indicates that electronic detonators will develop toward serialization and standardization, the electronic detonator initiation technology will develop toward more intelligence, the electronic detonator delay design theory will develop toward short delay, and the electronic detonator initiation network will develop toward a large scale. Based on engineering practices, we summarized the technological and application problems of electronic detonators, including frequent occurrence of misfire detonation, disconnection between detonation research and application, limited product types, and a defective standards system. Considering the demand of the civil explosive industry, we proposed the following key research directions: theories of precise delay-controlled blasting, integration of information technology with electronic detonator initiation, series of differentiated electronic detonator products, and standards systems of electronic detonators.

The technology for gob-side entry retaining in steep coal seams is still in the development stage. The analysis results of the caving structure of main roof, low influence of gateway's stability because of long filling distance and weak dynamic effect of the gateway, and the low stress redistribution environment indicate that using this technology in steep coal seams has significant advantages. Moreover, to reinforce the waste rock and the soft floor and to better guard against the impact of the waste rock during natural filling, a rock blocking device and grouting reinforcement method were invented, and theoretical calculations result show that the blocking device has high safety factor. In addition, we also developed a set of hydraulic support devices for use in the strengthening support zone. Furthermore, because the retaining gateway was a systematic project, the selection of the size and shape of the gateway cross section and its support method during the initial driving stage is a key step. Thus, first, a section the size of bottom width and roof height of a new gateway was determined to meet any related requirements. Then, according to the cross sections of 75 statistical gateways and the support technique, it chosen a trapezoidal cross section when the dip of the coal seam is 35° < α ≤ 45°, a special and an inclined arch cross section when 45° < α ≤ 55°. Eventually, a support system of bolts and cables combined with steel mesh and steel belts was provided. The support system used optimized material and improved parameters, can enhanced the self-bearing ability of the surrounding coal and rock masses.