Experimental and numerical research on fracture behaviors of sandstone under different loading rates
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ORIGINAL ARTICLE
Experimental and numerical research on fracture behaviors of sandstone under different loading rates Zhenlong Zhao . Hongwen Jing
. Xinshuai Shi . Yuan Gao
Received: 2 December 2019 / Accepted: 17 September 2020 Ó Springer Nature Switzerland AG 2020
Abstract The macroscopic deformation process of rock is the external performance of microscopic damage in essence, and research from the macro and micro perspectives can effectively reveal the failure mechanism of rock. To further investigate the fracture behaviors of yellow sandstone disc specimens under different loading rates, seven groups of Brazilian disc splitting tests with different loading rates from 1 9 10–6 to 1 9 10–4 s–1 were carried out. A systematical investigation of loading rate effect on macroscopic mechanical responses and microscopic damage characteristics has been conducted from the stress– strain relationship obtained from material testing system, from damage three-dimensional localization based on acoustic emission techniques, and from fracture morphology by scanning electron microscope. In addition to laboratory experiment, parallel bond models of different grain size distribution indexes based on particle flow code were established.
The coupling effect of loading rate and grain size distribution index was further analyzed. The results interpret that the effect of loading rate on rock fracture behaviors is determined by the process of crack initiation, propagation and coalescence, and it is also affected by distribution of different size grains. The differences of rock fracture behaviors under different loading rates were discussed from the mechanism of energy input and dissipation. The research have actual significance for stability design and evaluation of rock excavation engineering.
Z. Zhao H. Jing (&) X. Shi Y. Gao State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China e-mail: [email protected]
1. Tensile strength increases linearly with logarithmic of quasi-static loading rate while its increasing trend gradually slows down. 2. According to acoustic emission and SEM micrograph, roughness and fragmentation of the fracture surface increase with increasing loading rates. 3. Process of energy input and dissipation is closely related to loading rates, which corresponds to process of cracks growth.
X. Shi Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan Y. Gao Department of Civil Engineering, Monash University, Clayton, VIC 3800, Australia
Keywords Brazilian disc test Loading rate Fracture behavior Acoustic emission Particle flow code
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Geomech. Geophys. Geo-energ. Geo-resour.
2 Introduction In rock mass engineering, such as underground mining, tunnel, water conservancy and hydropower construction, stability of surrounding rock is of utmost importance during the period of excavation and us
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