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In case of deep mining engineering, the conventional gob-side entry retaining (GER) method encounters inevitable difficulties, due to high stress, high dynamic disturbance and large deformation issues. Recently, an innovative no-pillar mining approach of GER is proposed and applied in several realistic cases. According to the innovative approach, two novel techniques, the pre-fracturing on the roof before mining activities, and a novel support system with a good energy-absorbing capacity, make it possible to effectively restrain the large deformation in the deep surrounding rock. In this study, the innovative mining approach with the corresponding energy-absorbing support systems in deep mining is systematically presented. The pre-fracturing effect, taking into account the novel support system, is demonstrated in a numerical approach, and the numerical results are compared with those of the conventional method. Finally, some real monitoring data from the Chengjiao coal mine are given to further prove the advantages of the innovative mining method with energy-absorbing support systems. This work provides an effective and economical method to non-pillar mining in deep coal mine.

In order to increase the mining rate of underground coal resources, an innovative nonpillar underground coal mining approach (fracturing roofs to maintain entry (FRME)) has been widely applied in China. The effect of roof fracturing determines whether the entry can be retained successfully or not. In this work, the tail entry of 21304 panel in Chengjiao Coal Mine (China) has been considered as the test site. The coal mine is located approximately 900 m underground. A numerical investigation on the relationship between the entry stability and roof fracturing angle was conducted. In order to investigate the reasonable scope of roof fracturing angle under static and dynamic loadings, the double-yield model was employed to simulate the gob materials, and the input parameters of the model were calibrated meticulously using the method of inversion analysis. Furthermore, dynamic loading was applied to research the influence of fracture of hard rock strata on the entry stability. The global model was validated with the field data. The simulation results demonstrate that the reasonable scope of the roof fracturing angle is 10–20°, in which case the distributions of vertical stress are favorable to the stability of gob-side entry. Additionally, the dynamic responses were found to be relatively moderate. The numerical method could provide a significant reference for the design of FRME approach.