Dynamic Mechanical Behaviors and Failure Mechanism of Lignite under SHPB Compression Test

Yanqi Song, Hongfa Ma (), Jiangkun Yang, Junjie Zheng, Juntao Yang and Wei Bao
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Yanqi Song: State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing 100083, China
Hongfa Ma: State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing 100083, China
Jiangkun Yang: School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Junjie Zheng: School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Juntao Yang: School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Wei Bao: School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China

Sustainability, 2022, vol. 14, issue 17, 1-19

Abstract: There is an obvious impact effect of on-site blasting on the slope coal mass of open-pit mines, so it is of great significance to study the dynamic mechanical response characteristics of coal rock for slope stability control. In this paper, first, the mineral composition and microstructure of lignite from open-pit mine are analyzed, and it is found that the content of non-organic minerals in lignite such as clay accounts for more than 24.40%; meanwhile, the rock sample has obvious horizontal bedding characteristics and mainly micro pores and transition pores inside; further, there are obvious banded areas with high water content in the rock, which has the same extending direction as the beddings. Based on the SHPB test system, the dynamic compression tests of lignite with different impact velocities are carried out. The results show that there is a significant hardening effect caused by the increase of strain rate on the dynamic mechanical parameters of rock samples, and the stress–strain curve has obvious “double peak” characteristics; meanwhile, the macroscopic crack of the rock appears at the first stress peak and disappears after further compression until the interlayer fracture occurs; further, the fracture fractal dimension of lignite increases linearly with the impact velocity, revealing that the fragmentation of rock samples increases gradually. In addition, with the increase of impact velocity, the input energy and dissipated energy of rock samples increase linearly, while the elastic property increases slowly and at a low level. The bedding characteristics of lignite and the wave impedance difference between the layers cause the high-reflection phenomenon in the process of stress-wave propagation, and then produce the obvious tensile stress wave in the rock sample, which finally results in the interlayer fracture failure of the rock.

Keywords: lignite; mineral composition; microstructure; dynamic mechanical behaviors; fracture fractal dimension; failure mechanism (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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