Fracturing Behavior Study of Three-Flawed Specimens by Uniaxial Compression and 3D Digital Image Correlation: Sensitivity to Brittleness

Brittleness has significant effects on the fracturing behaviors of preflawed rock-like materials. In this study, uniaxial compressive experiments are conducted on rock-like specimens containing three flaws, and a three-dimensional digital image correlation technique is applied to capture the real-time displacement and strain fields on the rock-like specimens’ surface. The present experimental study focuses on the effects of the brittleness of rock-like materials on crack initiation, propagation, and coalescence behaviors in three flaw-contained specimens. The experimental results show that the crack initiation mode transforms from the tensile mode to the shear mode with a decrease in the brittleness index of rock-like materials. Meanwhile, crack coalescence modes transform from the tensile crack coalescence mode to the mixed tension–shear coalescence mode, then to the shear coalescence mode as the brittleness index of rock-like materials decreases. Moreover, the ratio of the crack initiation stress to the peak stress increases, while the ratio of the crack coalescence stress to the peak stress decreases as the brittleness index decreases. This paper also addresses the influences of the rock bridge angle on the mechanical and cracking behaviors of three flaw-contained specimens. For specimens with the lower brittleness index, the ratio of the crack initiation stress to the peak stress decreases, while the ratio of the crack coalescence stress to the peak stress increases as the rock bridge angle increases. However, for specimens with the higher brittleness index, the ratio of the crack initiation stress to the peak stress and the ratio of the crack coalescence stress to the peak stress decrease with increasing the rock bridge angle. The experimental results provide a better understanding of the sensitivity of mechanical and cracking behaviors of three flaw-contained specimens to the brittleness of rock-like materials under uniaxial compression.

[1]  L. Wong,et al.  Crack Coalescence in Molded Gypsum and Carrara Marble: Part 1. Macroscopic Observations and Interpretation , 2009 .

[2]  Z. Chen,et al.  An investigation into fracture behavior of geopolymer concrete with digital image correlation technique , 2017 .

[3]  C. Martin.  Brittle failure of rock materials: test results and constitutive models , 1996 .

[4]  Hao Cheng,et al.  An Experimental Study of Crack Coalescence Behaviour in Rock-Like Materials Containing Multiple Flaws Under Uniaxial Compression , 2014, Rock Mechanics and Rock Engineering.

[5]  Xiaoping Zhou,et al.  Numerical simulation of propagation and coalescence of flaws in rock materials under compressive loads using the extended non-ordinary state-based peridynamics , 2016 .

[6]  A. Taheri,et al.  Fracture Energy-Based Brittleness Index Development and Brittleness Quantification by Pre-peak Strength Parameters in Rock Uniaxial Compression , 2016, Rock Mechanics and Rock Engineering.

[7]  Dong Lei,et al.  Experimental research on impact damage of Xiaowan arch dam model by digital image correlation , 2017 .

[8]  Eurípedes do Amaral Vargas,et al.  Application of the discrete element method for modeling of rock crack propagation and coalescence in the step-path failure mechanism , 2013 .

[9]  Qiuming Gong,et al.  Influence of rock brittleness on TBM penetration rate in Singapore granite , 2007 .

[10]  Shanyong Wang,et al.  An Experimental Study of the Fracture Coalescence Behaviour of Brittle Sandstone Specimens Containing Three Fissures , 2012, Rock Mechanics and Rock Engineering.

[11]  S. M. Lee,et al.  Analysis of rockbursts that have occurred in a waterway tunnel in Korea , 2004 .

[12]  Yunteng Wang,et al.  A 3-D conjugated bond-pair-based peridynamic formulation for initiation and propagation of cracks in brittle solids , 2017 .

[13]  Yunteng Wang,et al.  Three-dimensional numerical study on the failure characteristics of intermittent fissures under compressive-shear loads , 2018, Acta Geotechnica.

[14]  R. Altindag,et al.  A brittleness index to estimate fracture toughness , 2004 .

[15]  B. Tarasov,et al.  Universal criteria for rock brittleness estimation under triaxial compression , 2013 .

[16]  Sheng-Qi Yang,et al.  Crack coalescence behavior of brittle sandstone samples containing two coplanar fissures in the process of deformation failure , 2011 .

[17]  S. Kahraman,et al.  Correlation of TBM and drilling machine performances with rock brittleness , 2002 .

[18]  Antonio Bobet,et al.  Crack coalescence in specimens with open and closed flaws: A comparison , 2009 .

[19]  Xiating Feng,et al.  Do disk-type specimens generate a mode II fracture without confinement? , 2016 .

[20]  V. Hucka,et al.  Brittleness determination of rocks by different methods , 1974 .

[21]  Herbert H. Einstein,et al.  Coalescence of fractures under shear stresses in experiments , 1995 .

[22]  Hui Zhou,et al.  Evaluation Methodology of Brittleness of Rock Based on Post-Peak Stress–Strain Curves , 2015, Rock Mechanics and Rock Engineering.

[23]  W. F. Ranson,et al.  Applications of digital-image-correlation techniques to experimental mechanics , 1985 .

[24]  Y. Ju,et al.  An Experimental and Numerical Study on Cracking Behavior of Brittle Sandstone Containing Two Non-coplanar Fissures Under Uniaxial Compression , 2016, Rock Mechanics and Rock Engineering.

[25]  Boris Tarasov,et al.  Absolute, relative and intrinsic rock brittleness at compression , 2012 .

[26]  Xiaoping Zhou,et al.  Localization of deformation and stress–strain relation for mesoscopic heterogeneous brittle rock materials under unloading , 2005 .

[27]  Xiaoping Zhou,et al.  The modeling of crack propagation and coalescence in rocks under uniaxial compression using the novel conjugated bond-based peridynamics , 2017 .

[28]  Antonio Bobet,et al.  Active Seismic Monitoring of Crack Initiation, Propagation, and Coalescence in Rock , 2017, Rock Mechanics and Rock Engineering.

[29]  Ping Cao,et al.  Crack propagation and coalescence of brittle rock-like specimens with pre-existing cracks in compression , 2015 .

[30]  Sheng-Qi Yang,et al.  Experimental study on mechanical behavior of brittle marble samples containing different flaws under uniaxial compression , 2009 .

[31]  Yunteng Wang,et al.  Numerical simulation of initiation, propagation and coalescence of cracks using the non-ordinary state-based peridynamics , 2016, International Journal of Fracture.

[32]  K. T. Chau,et al.  Analysis of crack coalescence in rock-like materials containing three flaws—Part I: experimental approach , 2001 .

[33]  Yun-Teng Wang,et al.  Numerical simulation of crack propagation and coalescence in pre-cracked rock-like Brazilian disks using the non-ordinary state-based peridynamics , 2016 .

[34]  Dongxiao Zhang,et al.  Multi-crack interaction in limestone subject to stress and flow of chemical solutions , 2009 .

[35]  Yin-Ping Li,et al.  Experimental research on pre-cracked marble under compression , 2005 .

[36]  Joseph F Labuz,et al.  Fracture of sandstone characterized by digital image correlation , 2013 .

[37]  Jiang Zhu,et al.  The Effects of Crack Openings on Crack Initiation, Propagation and Coalescence Behavior in Rock-Like Materials Under Uniaxial Compression , 2016, Rock Mechanics and Rock Engineering.

[38]  Herbert H. Einstein,et al.  Crack coalescence in brittle material under cyclic loading , 2006 .

[39]  Louis Ngai Yuen Wong,et al.  Systematic evaluation of cracking behavior in specimens containing single flaws under uniaxial compression , 2009 .

[40]  Hubert W. Schreier,et al.  Image Correlation for Shape, Motion and Deformation Measurements: Basic Concepts,Theory and Applications , 2009 .

[41]  Abbas Taheri,et al.  Pre-Peak and Post-Peak Rock Strain Characteristics During Uniaxial Compression by 3D Digital Image Correlation , 2016, Rock Mechanics and Rock Engineering.

[42]  L. Wong,et al.  Investigating the effects of micro-defects on the dynamic properties of rock using Numerical Manifold method , 2014 .

[43]  H. H. Einstein,et al.  Crack Coalescence in Molded Gypsum and Carrara Marble: Part 2—Microscopic Observations and Interpretation , 2008 .

[44]  Antonio Bobet,et al.  Coalescence of multiple flaws in a rock-model material in uniaxial compression , 2002 .

[45]  Zhang Lei,et al.  Investigation of the deformation properties of asphalt mixtures with DIC technique , 2012 .

[46]  Antonio Bobet,et al.  Crack initiation, propagation and coalescence from frictional flaws in uniaxial compression , 2010 .