University of Oulu

Zhang, N., Zhang, ZX., Shan, R. et al. An experimental study of fault slips under unloading condition in coal mines. Bull Eng Geol Environ 82, 126 (2023).

An experimental study of fault slips under unloading condition in coal mines

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Author: Zhang, Ningbo1,2,3,4; Zhang, Zong‑Xian2; Shan, Renliang1;
Organizations: 1School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, China
2Oulu Mining School, University of Oulu, 90570 Oulu, Finland
3Mine Safety Technology Branch, China Coal Research Institute, 100013 Beijing, China
4State Key Laboratory of Coal Mining and Clean Utilization, China Coal Research Institute, 100013 Beijing, China
5Institute of Geology, China Earthquake Administration, 100029 Beijing, China
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 7.4 MB)
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Language: English
Published: Springer Nature, 2023
Publish Date: 2023-09-26


To investigate the mechanism of fault slips in coal mines, a biaxial shear experiment was carried out under unloading condition based on the fault F16 in Yima city, China. Two rock samples were used in the experiment and each sample was composed of two triangular sandstone blocks which were put together to simulate the fault. One rock sample was used to do fault slip tests and it was called slip-test sample. The other sample for comparison with the slip-test one was untested, and it was named non-slip-test sample. During the biaxial shear experiment of the slip-test sample, normal and shear strains near the fault, acoustic emission (AE) signals, and the sliding displacement were measured. After the experiment, microscopic profiles of fault surfaces of both rock samples were examined by scanning electron microscope (SEM). In addition, a numerical simulation was conducted to model the slip of the fault F16. The results indicate that: (1) three fault slips occurred during the biaxial shear experiment, and the shear stress, normal and shear strains in the first slip showed the maximum variation among three slips; (2) Shear strains near the two ends of the fault had a more significate variation than that in the middle part, and the typical trend of shear strains was first dropping, then increasing rapidly, and then falling slowly to a specific value during the first slip; (3) The first slip had the largest sliding displacement of 29.89 μm, and in the first slip three phases including slow slip, main shock and aftershock occurred based on AE monitoring results. (4) On the fault surface of non-slip-test sample, microstructures such as bulges, voids and veins were ubiquitous and notable, making the fault surface much rough, while similar microstructures were few and the fault surface of the slip-test sample was flattened after fault slips; (5) The slipping direction in the shallow part and deep part of the fault F16 were opposite during mining.

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Series: Bulletin of engineering geology and the environment
ISSN: 1435-9529
ISSN-E: 1435-9537
ISSN-L: 1435-9529
Volume: 82
Issue: 4
Article number: 126
DOI: 10.1007/s10064-023-03125-3
Type of Publication: A1 Journal article – refereed
Field of Science: 1171 Geosciences
Funding: Authors acknowledge the financial support from National Natural Science Foundation of China (No. 51874176, 52034009) and China Coal Research Institute (No. 2019CX-II-12, 2020CX-I-08). Open Access funding provided by University of Oulu including Oulu University Hospital. The first author is also grateful for the support from China Scholarship Council (CSC) (Grant No. 202006430042).
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