Crack growth mechanisms from 3-D surface flaw with varied dipping angle under uniaxial compression

Y. S H Guo, R. H C Wong, Kam Tim Chau, W. S. Zhu, S. C. Li

Research output: Journal article publicationConference articleAcademic researchpeer-review

4 Citations (Scopus)

Abstract

A number of instability problems in rock engineering projects are caused by crack propagation. However, crack growth mechanisms from 3-dimentional flaw are not fully understood, in particular for 3-D flaw case with varied dipping angle. This study focuses on 3-D surface flaw using real rock specimens containing a flaw with varied inclination angle a from axial loading and dipping angle γ from specimen surface under uniaxial compression. Acoustic emission technique was used for tracing the initiation and growth of micro-cracks inside of specimen. It was found that crack growth process is affected by the dipping angle γ of the 3-D flaw. When dipping angle γ ≠ 90°, the thickness of rock above the flaw plane is thinner than that of below the flaw plane. As a result, compressive crack and wing crack initiated easily from the thinner flaw tips. And, the normalized stress for crack initiation σi/σc, AE events and the AE energy for crack growth decreases with the dipping angle γ. However, for γ = 90°, the thickness of rock above and below of the flaw tips is the same, it was observed that anti-wing crack (crack growth direction opposite to wing crack) initiated first at a certain place away from the flaw tips, then wing crack and compressive crack emerged at the late stage. For this case, the stress σi/σc, AE events and the AE energy for crack initiation and propagation are at a high value. Thus, for rock mass contains flaws geometry with small dipping angle, some problems of crack propagation may be induced easily during excavation.
Original languageEnglish
Pages (from-to)2353-2356
Number of pages4
JournalKey Engineering Materials
Volume353-358
Issue numberPART 4
Publication statusPublished - 19 Nov 2007
EventAsian Pacific Conference for Fracture and Strength (APCFS'06) - Sanya, Hainan Island, China
Duration: 22 Nov 200625 Nov 2006

Keywords

  • AE event
  • Anti-wing crack
  • Dipping angle
  • Surface flaw
  • Wing crack

ASJC Scopus subject areas

  • Ceramics and Composites
  • Chemical Engineering (miscellaneous)

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