The purpose of this paper is to provide scientific basis for the stability evaluation of overburden rock of repeated mining goaf under the expressway. The objectives of the present study are to reveal the development of overburden rock fractures under repeated mining and to identify the fractal characteristics of the overburden rock fractures. The results show that (1) the separation fracture and vertical fracture fissure are developed in the overburden rock under repeated mining; (2) after the mining of the lower coal seam, the fractures developed in the overburden rock of the goaf are obviously retained in general. The number of fractures on both sides of the goaf is relatively large, while in the central part, it is relatively small and the fractures in most areas are basically closed; (3) under the same advancing length of working face in the lower coal seam, the fractal dimension in the caving zone is larger than that of the fractured zone; (4) with the increase of the advancing length of working face in the lower coal seam, the variation trend of the fractal dimension appears from small to large and then to small and stable; (5) when the repeated mining is over and the overburden rock movement is basically stable, the ratio of the fractal dimension in the caving zone and the fractured zone is 1.067:1. The results have an important reference value for ensuring the safety of the expressways above the repeated mining goaf in Shanxi region and similar areas.
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The authors gratefully appreciate all the valuable comments and suggestions from the anonymous reviewers and editors, which helped to improve the quality of the manuscript greatly.
This study was supported in part by the National Natural Science Foundation of China (No. 41572221) and the National Natural Science Foundation of China (No. 41807195).
Responsible Editor: Longjun Dong
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Zhang, Z., Zhang, Y., Xu, Y. et al. Fracture development and fractal characteristics of overburden rock under repeated mining. Arab J Geosci 14, 225 (2021). https://doi.org/10.1007/s12517-021-06524-6
- Caving zone
- Fractured zone
- Advancing length
- Variation trend
- Fractal dimension