- Title
- A new prediction method for multi-crack initiation of anisotropic rock
- Creator
- Sun, Dongliang; Rao, Qiuhua; Wang, Shanyong; Yi, Wei; Zhao, Chenchen
- Relation
- Theoretical and Applied Fracture Mechanics Vol. 118, Issue April 2022, no. 103269
- Publisher Link
- http://dx.doi.org/10.1016/j.tafmec.2022.103269
- Publisher
- Elsevier
- Resource Type
- journal article
- Date
- 2022
- Description
- Multi-crack initiation prediction of anisotropic rock is very important for designing fracture-networks and improving efficiency of shale-gas exploitation. Current literature is mainly focused on multi-crack interacting stress intense factors (SIFs) but less on multi-crack initiation criterion for anisotropic rock. In this study, a new multi-crack initiation criterion of anisotropic rock is established based on the maximum ratio of Mode I and Mode II SIF to its fracture toughness on the critical crack plane (θIC or θIIC), / and /, in order to predict the multi-crack initiation parameters (crack initiation tip, angle and mode). Effects of crack relative position (α1, γ, Dh and Ds) and sedimentary angle (β) on / and / are analyzed for anisotropic rock. Research results show that under uniaxial compression stress, two collinear cracks are always initiated at two inner-tips simultaneously in Mode I (with large crack incline angle, e.g., α1 ≥ 28°) or in Mode II (with small crack incline angle, e.g., α1 < 28°). Two vertical cracks (α1 = 45°, α2 = 135°, with extension line of one crack passing through the center of another crack) are initiated at only one crack-tip for any sedimentary plane angle (β = 0°∼180°) in Mode I. Two arbitrary cracks are initiated at one crack-tip in Mode II only when the absolute value of two-crack incline angles with respect to horizontal direction are both small (e.g., |α1|=10°<28°, |α2|=20°<28°). Theoretical prediction results are in good agreement with uniaxial-compression test results of shale and sandstone plates with two arbitrary cracks. The new multi-crack initiation criterion can be further developed to predict the whole multi-crack propagation process of anisotropic rock. It provides a theoretical basis for safety assessment of rock engineering and cracking-network formation of shale-gas hydraulic exploitation.
- Subject
- multi-crack initiation criterion; initiation mechanism; interacting SIFs; anisotropic rock; uniaxial compression test
- Identifier
- http://hdl.handle.net/1959.13/1473847
- Identifier
- uon:49129
- Identifier
- ISSN:0167-8442
- Language
- eng
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