Initiation of tensile and mixed-mode fracture in sandstone

Lin, Qing; Fakhimi, A.; Haggerty, M. E.; Labuz, Joseph F.

doi:10.1016/j.ijrmms.2008.10.008

Cited by 65 publications

(33 citation statements)

References 14 publications

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“…Therefore, investigating the crack initiation angle and the crack propagation path under the mixed loading mode are favorite subjects for researchers in the field of rock mechanics. There are a large number of theoretical models (Erdogan and Sih, 1963;Hussain et al, 1974;Nuismer, 1975;Palaniswamy and Knauss, 1972;Sih, 1974;Theocaris and Andrianopoulos, 1982) and experimental techniques (Grassl and Rempling, 2007;Isaksson and Ståhle, 2002;Lin et al, 2009;Song et al, 2004;Xeidakis et al, 1997) for investigating the mixed mode of crack growth in rock materials. Theoretical failure criteria such as the Maximum Tangential Stress (MTS) criterion (Erdogan and Sih, 1963), the minimum strain energy density criterion (Sih, 1974), and the maximum energy release rate criterion (Hussain et al, 1974) have been frequently used by researchers working on rock and geo-material fields in order to estimate the direction of the mixed mode in the crack growth process.…”

Section: Introductionmentioning

confidence: 99%

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Eftekhari

Baghbanan

Mohtarami

et al. 2017

jtam

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The crack initiation angle and propagation path for two different disc shaped test specimens (i.e., SCB and CBD specimen) are investigated experimentally and theoretically. The Maximum Tangential Stress (MTS) criterion does not calculate the crack initiation angle in SCB and CBD specimens correctly. Moreover, at the angles after occurrence of pure mode II, where the stress intensity factor of mode I becomes negative, this criterion is not applicable. Therefore, in this research work, Improved MTS (IMTS) criterion which has been implemented in the extended finite element method and is applicable under tensile and compressive loading conditions to examine the crack propagation path in the aforementioned disc shaped specimens. Furthermore, an experimental study on a cracked Brazilian disc specimen has been conducted at different angles. Results of IMTS criterion in these specimens show that the crack propagation path and the crack initiation angle can be predicted theoretically by using IMTS criterion.

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Section: Introductionmentioning

confidence: 99%

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Eftekhari

Baghbanan

Mohtarami

et al. 2017

jtam

View full text Add to dashboard Cite

show abstract

“…They showed that the correlation factor between the mechanical behavior and the petrographic parameters revealed that the cement content is not the only factor governing the UCS, and the composition of the cement may play an important role in the UCS of clay-bearing sandstones. Due to the difficulty of direct tensile testing, Lin et al (2009) conducted several three-point bending tests on Berea sandstone to study fracture initiation and the associated damage zone by using 2D acoustic emission (AE) locations and electronic speckle pattern interferometry (ESPI). Their experiments indicated that specimen failure was initiated by a large fracture with a localized damage zone.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Strength, Deformability, Failure Behavior and Acoustic Emission Locations of Red Sandstone Under Triaxial Compression

2012

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Conventional triaxial compression and ''reducing confining pressure'' experiments were carried out for red sandstone by an MTS815 Flex Test GT rock mechanics experimental system. Our results show that the post-peak axial deformation characteristics of red sandstone changed as the confining pressure was increased from 5 to 65 MPa. Young's modulus of red sandstone increased nonlinearly with increasing confining pressure, but Poisson's ratio remained unaffected. Using our new data, the compactive and dilatant behavior, strength and failure characteristics of sandstone under triaxial compression are further discussed. For our data, the nonlinear Hoek-Brown criterion better reflects the peak strength properties than the linear MohrCoulomb criterion. However, the residual strength shows a clear linear relationship with confining pressure, which can be best described using the linear Mohr-Coulomb criterion. The peak and residual strengths were not directly related to the two different loading paths. The onset of dilatancy (C 0 ), the switch from compaction-dominated to dilatant-dominated behavior (D 0 ) and the stress at zero volumetric strain all increased linearly with the confining pressure. In our conventional triaxial compression experiments, the failure mode changed from mixed tension and shear fracture (single shear fracture) to shear fracture with double slippage planes with increasing confining pressure. However, the failure mode in our ''reducing confining pressure'' experiments was more complicated and results mainly from the unstable failure characteristics of the rock during the reduction in confining pressure. Finally, based on our acoustic emission (AE) locations, at a confining pressure of 35 MPa, a detailed analysis of the evolutionary process of internal cracks is presented for the entire loading process.

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“…We find that only the IH-PD model delivers damage patterns and crack profiles similar to those seen in experiments in. 9…”

Section: Peridynamic Modeling Of Damage Evolution In Porous Materialsmentioning

confidence: 99%

A peridynamic model for damage and fracture in porous materials

Chen¹,

Niazi²,

Bobaru³

2019

Preprint

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(This paper is submitted to "International Journal of Rock Mechanics and Mining Sciences") We introduce a peridynamic (PD) model for simulating damage and fracture in porous materials based on an Intermediate Homogenization (IH) approach. In this approach, instead of explicitly representing the detailed pore geometry, we use homogenization but maintain some information about the microstructure (porosity) in the model. Porosity is introduced in the model as initial peridynamic damage, implemented by stochastically pre-breaking peridynamic bonds to match the desired porosity value. We validate the model for elastodynamics with wave propagation in porous glasses, where we match observed wave propagation speeds and the apparent elastic moduli for various porosities. The model is then used to study the fracture behavior of Berea sandstone under three-point bending loading conditions. We validate the model for fracture problems using the case of failure in a sandstone sample with an off-center pre-notch under three-point bending. The IH-PD results agree very well with experiments: we obtain different failure modes depending on the length of the off-center pre-notch. When the pre-notch is short, most damage (and the subsequent failure) happens in the center of the beam (largest tensile stresses in an un-notched sample). In this case, material porosity makes the fracture behavior “insensitive” to the presence of the off-center pre-notch. When the pre-notch is long, damage starts from near its tip, and progresses in mixed mode towards the loading point. The model captures the location of crack initiation to be the right-corner of the notch, exactly as shown by the experimental acoustic emission results. A fully-homogenized model for the porous sandstone fails to reproduce the failure mode sensitivity on the pre-notch length. The results show the importance of using the IH-PD model when trying to capture the important effects local heterogeneities (like pores) have on damage initiation and growth in porous materials.

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Initiation of tensile and mixed-mode fracture in sandstone

Cited by 65 publications

References 14 publications

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Experimental Investigation on the Strength, Deformability, Failure Behavior and Acoustic Emission Locations of Red Sandstone Under Triaxial Compression

A peridynamic model for damage and fracture in porous materials

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