Study on the maximum tangential strain criterion for the initiation of the wing-crack under uniaxial compression

2021 ◽  
Vol 116 ◽  
pp. 103085
Author(s):  
Fengjin Zhu ◽  
Hongyan Liu ◽  
Leihua Yao ◽  
Gang Mei
Keyword(s):  
Uniaxial Compression ◽  
Wing Crack ◽  
Strain Criterion ◽  
Tangential Strain

Anti-Wing Crack Growth from Surface Flaw in Real Rock under Uniaxial Compression

2008 ◽  
pp. 825-826 ◽  
Author(s):  
Robina H. C. Wong ◽  
Y. S. H. Guo ◽  
L. Y. Li ◽  
K. T. Chau ◽  
W. S. Zhu ◽  
...  
Keyword(s):  
Crack Growth ◽  
Uniaxial Compression ◽  
Surface Flaw ◽  
Wing Crack

Crack Growth Mechanisms from 3-D Surface Flaw with Varied Dipping Angle under Uniaxial Compression

2007 ◽  
Vol 353-358 ◽  
pp. 2353-2356 ◽  
Author(s):  
Y.S.H. Guo ◽  
R.H.C. Wong ◽  
K.T. Chau ◽  
Wei Shen Zhu ◽  
Shu Cai Li
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Crack Growth ◽  
Uniaxial Compression ◽  
Axial Loading ◽  
Growth Direction ◽  
Surface Flaw ◽  
Growth Mechanisms ◽  
Wing Crack ◽  
Ae Energy

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 α 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 ≠ 90º, 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 = 90º, 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.

Analysis of Failure Mode and Propagation for Crack in Uniaxial Compression

2012 ◽  
Vol 166-169 ◽  
pp. 2929-2932
Author(s):  
Ya Zhen Sun ◽  
Xiao Xing Zhai ◽  
Jie Min Liu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Failure Mode ◽  
Uniaxial Compression ◽  
Process Analysis ◽  
Failure Process ◽  
Inclined Crack ◽  
Wing Crack ◽  
Dimensionless Stress

This paper analyzed the failure mode for crack in uniaxial compression according to the stress intensity factor, and obtain that the failure mode for crack in uniaxial compression is compression-shear. The wing crack was deformed, after the crack tip initiate. By analyzing the dimensionless stress intensity factor, we obtain that the failure mode for wing crack in uniaxial compression is tension-shear, and we obtain that the dimensionless stress intensity factor for wing crack decreased with inclined angle increased. The inclined crack propagation in uniaxial compression was numerically studied using rock failure process analysis code (rfpa), and obtain that one inclined crack in uniaxial compression formed mode I offset crack parallel to load direction in the end. The numerical results of failure mode are accordance with stress intensity factor.

Numerical Studies of End Effect on Crack Propagation Behavior of Brittle Specimen Containing Pre-Existing Crack under Uniaxial Compression

2007 ◽  
Vol 353-358 ◽  
pp. 1049-1052
Author(s):  
Ming Li Huang ◽  
Shan Yong Wang ◽  
Wei Lu ◽  
Wan Cheng Zhu
Keyword(s):  
Crack Propagation ◽  
Uniaxial Compression ◽  
Process Analysis ◽  
Failure Process ◽  
End Effect ◽  
Wing Crack ◽  
Propagation Length ◽  
Propagation Behavior ◽  
Numerical Studies ◽  
Crack Propagation Process

In this paper, a Material Failure Process Analysis code (MFPA2D) was employed to investigate the interaction of end effect zone of specimen with the wing crack propagation inside the brittle specimen containing pre-existing flaws under uniaxial compression comparing with the experimental results. The numerical results show that the shorter the distance between the pre-existing flaw and the specimen's end , the slower the crack propagation process and the shorter wing propagation length is , and vice versa. In addition, the end effect zone was also influenced by the wing crack propagation.

scholarly journals Study on the Interaction of Collinear Cracks and Wing Cracks and Cracking Behavior of Rock under Uniaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Chaolin Wang ◽  
Yu Zhao ◽  
Yanlin Zhao ◽  
Wen Wan
Keyword(s):  
Uniaxial Compression ◽  
Inclination Angle ◽  
Shear Crack ◽  
Crack Coalescence ◽  
Crack Interaction ◽  
Shear Cracks ◽  
Collinear Cracks ◽  
Wing Crack ◽  
Cracking Behavior ◽  
Initiation And Propagation

This paper investigates the crack interaction, initiation, and propagation rules of rock-like materials containing two collinear cracks. Based on the Kachanov method, the formulations for stress intensity factors (SIFs) of two collinear cracks and two winged cracks are derived, respectively. The influences of bridge ligament and crack length on the crack interaction are analyzed theoretically. The results show that the propagation of a long crack is independent of crack interaction when d≥a2 and the same rule applies for a short crack when d≥a1. With the growth of wing cracks, the SIF of wings first remarkably decreases and then it tends toward a steady value. Subsequently, the propagation of collinear cracks and cracking processes under uniaxial compression are analyzed experimentally and numerically. Both the experimental results and simulation results demonstrate that shear cracks tend to initiate and propagate at higher inclination angle. The crack coalescence is affected by the inclination angle of bridge ligament. For increasing the inclination angle, the crack coalescence varies from wing crack failure to shear crack coalescence. As bridge ligament increases, the crack coalescence varies from shear crack coalescence to shear-wing crack coalescence and then to wing crack failure.

scholarly journals Influence of Flaw Inclination Angle on Cracking Behavior of Rock-Like Materials under Uniaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Rongchao Xu
Keyword(s):  
Crack Initiation ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Failure Modes ◽  
Fractured Rock ◽  
Axial Stress ◽  
Uniaxial Compression Test ◽  
Wing Crack ◽  
Cracking Behavior ◽  
Secondary Cracks

The inclination angle of the flaw has an important effect on the cracking behavior of fractured rock. The influence of the inclination angle of closed flaw on the strength, cracking behavior, failure modes, and AE behaviors of specimens has not been investigated thoroughly. Uniaxial compression tests were conducted on gypsum samples containing a single closed flaw with different inclination angles. The flaw orientation influence on strength, cracking mechanism, failure modes, and AE behaviors was analyzed in detail. With the increase of the flaw inclination angle from 30° to 75°, the mechanical parameters such as elastic modulus, wing crack initiation strength, and uniaxial compression strength decrease first and then increase and reach the minimum value at 45°. The wing crack initiation angle decreases from 65° to 35° as the flaw inclination angle increases from 30° to 75°. The wing crack is more difficult to initiate from the tips of closed flaws compared with that of open flaws. The secondary cracks are initially shear cracks and propagate in a stable manner. However,when the axial stress reaches the peak strength, the secondary crack propagates unstably, which results in the macroscopic failure of the sample. The AE behaviors of samples are also analyzed during the uniaxial compression test. The experimental results are expected to provide helpful guidance for safe construction under fractured rock mass condition.

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