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The final publication is available at Springer via http://dx.doi.org/10.1007/s10064-022-02927-1. The bearing characteristics of random lumpiness gangue formed by rock fragmentation in gob roofs are important to ensure roadway stability in the new nonpillar mining approach. In this paper, the bearing characteristics of gangue are divided into bulking and compaction characteristics. Bulking characteristics mainly depend on the lumpiness and bulking coefficient of randomly lumpy gangue (KRAFT). This paper proposes a method to invert KRAFT of gangue samples with a small amount of lumpiness, and a random subset of 30% of an experimental sample of broken rocks is selected for analysis. The lumpiness distributions of the subset of samples and all the samples are normal, and the average lumpiness error of the subset is 0.54–2.86%. The ratio of average lumpiness to rock before breakage (KASB) is introduced as a parameter for analysis. The results show that KASB and KRAFT have a log-normal functional relationship, and KASB can be used to infer KRAFT from laboratory and field monitoring data. Compaction characteristics show that the relationship between KRAFT and the supporting force of gangue (sGB) is a power function, and sGB in gangue during different stages of compression in a gob can be obtained from the value of KRAFT obtained from experiments or field monitoring. This work is supported by the Open-end Research Fund of State Key Laboratory for Geomechanics and Deep Underground Engineering (SKLGDUEK2024), the National Key R&D Program (No. 2016YFC0600900), the National Natural Science Foundation of China (No. 52074295, 52074299, 41941018, 52074300), the Excellent Youth Fund of the Education Department of Hunan Province (21B0487) and China Scholarship Council (CSC NO. 202006430081), which are gratefully acknowledged. |
