Underlying Mechanisms of Crack Initiation for Granitic Rocks Containing a Single Pre-existing Flaw: Insights From Digita
- PDF / 6,615,098 Bytes
- 17 Pages / 595.276 x 790.866 pts Page_size
- 7 Downloads / 125 Views
ORIGINAL PAPER
Underlying Mechanisms of Crack Initiation for Granitic Rocks Containing a Single Pre‑existing Flaw: Insights From Digital Image Correlation (DIC) Analysis Liwang Liu1,2 · Haibo Li1,2 · Xiaofeng Li1 · Di Wu1,2 · Guokai Zhang3 Received: 2 December 2019 / Accepted: 21 October 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Determination on underlying mechanisms of crack initiation is of vital importance to understand the failure processes of geomaterials in practical engineering. In this study, uniaxial compression experiments of granitic samples containing a single pre-existing flaw were conducted and the failure processes were recorded by using the high-speed camera. To quantitatively determine the crack initiation mechanism, a novel method was first proposed based on digital image correlation (DIC) analysis and then its validity was confirmed. By utilizing this method, three types of cracks with different initiation mechanisms were identified and the effect of flaw inclination angle on crack initiation mechanisms was discussed from the viewpoint of theoretical analysis. With the increase of inclination angles, wing cracks change from mixed mode I/II cracks to mode I cracks, while anti-wing cracks have no evident changes and are dominated by mode II cracks. Under compressive pressure, the upper and bottom surfaces of pre-existing flaw deform to each other and the distributions of full-field tangential stress around flaw are different, which might induce the variation of crack initiation mechanisms with regard to the inclination angle. Keywords Crack initiation mechanisms · Digital image correlation (DIC) analysis · Wing cracks · Anti-wing cracks · Preexisting flaw
1 Introduction The failure of brittle materials which is associated with crack growth of intrinsic flaws commonly exists in the field of rock mechanics and engineering geology. From a large number of laboratory experimental results, the flaw existing in rock samples initiates and propagates at microscopic scale when subjected to external loading, which would induce the occurrence of some macroscopic phenomena, e.g., crack branching, volumetric dilation and brittle–ductile transition (Bieniawski 1967a, b; Nemat-Nasser et al. 1982; Horii and * Xiaofeng Li [email protected] 1
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
3
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
Nemat-Nasser 1985; Martin and Chandler 1994; Li et al. 2018a, b, 2019). In addition, many disasters were encountered in engineering geology, including the failure of pillar in mines (Esterhuizen et al. 2011), the stability of rock slope (Brideau et al. 2009) and fault reactivation (Sibson 1985; Petit and Barquins 1988), which had intimate connection with the crack growth of flaws. Therefore, conducting inve
Data Loading...
