The no-pillar mining method is widely used in coal mining engineering because of its superiority in resolving mine pressure hazards and protecting natural resources. In view of the geological conditions of stable strata in a coal mine of the Shandong Coal Zone, a novel segmented roadside plugging-filling mining method is proposed by introducing the filling coefficient into roadside filling. The operation process is designed with a new grouting filling forming device. Based on the relationship between the theoretical deflection of a cantilever beam and geometric settlement and parallel settlement models, strength formulas applicable to the segmented roadside plugging-filling (SRPF) method at different migration stages are obtained, and the deformation formulas of a roadway toward a rock slab are solved by an elastic equivalent model. Further, the determination procedure of the filling mode under the mining method is clarified. The SRPF method was implemented on a test stope, and the test results indicated that the theoretical deformation produced by the SRPF method was small and can meet the mining requirements. Through on-site test monitoring, the deformation of surrounding rock was 0–160 mm and the filling body under the SRPF method could maintain its own strength and the stability of the surrounding rock. In addition, entire successful mining been completed in the working stope, which further proves the applicability of this method. The backfilling cost of the gob-side filling was reduced by approximately 50%, and the backfilling efficiency was improved in the mine. The description of the novel mining method may provide theoretical and practical guidance for coal mining in similar geological conditions.

Grouting is always used in mine water plugging, reinforcement, and other disaster prevention projects. The diffusion mechanism of slurry in fractured rock is affected by geological environment and slurry performance, which should be revealed and characterized better. Based on the two-phase flow diffusion theory, a slurry diffusion model considering flowing water condition was established for a blocking area of a fracture zone in one case from China. The feasibility of two-phase flow model in grouting diffusion calculation was analyzed. The diffusion model in dynamic water environment was studied, and the diffusion range varying with time in the grouting area of Zhangji Coal Mine was explored. The optimization method of multi grouting holes was put forward, and the influence of water flowing was discussed. The results show that the slurry diffusion calculated by the two-phase flow model was feasible and consistent with the experimental study. The dynamic water can change the conventional circular diffusion state of slurry, but its pattern was oval and leaf type. There were different penetration distances in directions, and typical grouting voids were made on the side and upstream. When the single-hole grouting was carried out, the predetermined value can be achieved in the height range, but it was only about 15 m on the side because of the water flowing, which cannot meet the requirements. The optimization scheme of grouting was put forward, which adopted multiple grouting holes in the long side, and grouting in different directions and periods to avoid the possible problems of multihole intersection. The rationality and effectiveness of the proposed optimization method were verified through the calculation of water yield and analysis of cement composition from the drilling core in the grouted zone. In the grouting process, the water flowing has double effects, which has a significant role in promoting and scouring along the flow direction, but there is a significant weakness in the side diffusion. It is very important to realize the rational use of the dynamic water through the optimization scheme. This study is an important basic work of grouting mechanism, and it is expected to promote the development of grouting technology and application of two-phase fluid-solid coupling theory.

Microseismic (MS) technology is one of the effective methods for engineering fracture monitoring, and has been widely used in coal mining. Accurate P-phase arrivals are critical for improving accuracy of source locations and MS parameters. In this study, a multi-step method (CNN-KA) combining convolutional neural network (CNN) combined, K-means and Akaike information criterion (AIC) is proposed. Firstly, CNN is applied to recognize mining-induced waveforms of rock fractures. Secondly, maximum overlapping discrete wavelet transform and multi-resolution analysis are integrated to denoise for acquired waveforms. Subsequently, a new picker was developed by introducing K-mean clustering to AIC. Finally, performance of the proposed CNN-KA was evaluated with open-access and in-field data. Combined with software development, the proposed method was applied in 12123 working face of Paner coal mine in Anhui Province, China. The results show that accuracy of CNN-KA in recognizing mining-induced rock fracturing events is 98.11%. The mean absolute error of CNN-KA is 0.0915s at 200Hz frequency, which is 86.65% lower than STA/LTA (short-term average to long-term average, one of the most commonly used in MS technology). The error of picking and positioning are 3.7ms and 10.89m respectively at 5000Hz frequency. MS source parameters based on CNN-KA was effectively used to interpret the abnormal dynamic response of the roof stratum in 12123 working face of Paner coal mine, which was confirmed by real-time mine pressure and design data of the residual coal pillars. The results can be further used for calculating precise MS source parameters and early warning of engineering geohazards.