Development of a local degradation approach to the modelling of brittle fracture in heterogeneous rocks

Fang, Z.; Harrison, John P.

doi:10.1016/s1365-1609(02)00035-7

Cited by 177 publications

(115 citation statements)

References 32 publications

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“…The Weibull distribution function (Weibull 1939) is used to generate random distributions of the properties, as it has a simple structure and its applicability for modeling failure of brittle materials has been verified (Fang and Harrison 2002;Yang and Xu 2008;Gorjan and Ambrožič 2012). In this study, the fracture energy is considered as a random variable.…”

Section: Stochastic Approachmentioning

confidence: 99%

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

et al. 2018

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Reliable prediction of fracture process in shale-gas rocks remains one of the most significant challenges for establishing sustained economic oil and gas production. This paper presents a modeling framework for simulation of crack propagation in heterogeneous shale rocks. The framework is on the basis of a variational approach, consistent with Griffith's theory. The modeling framework is used to reproduce the fracture propagation process in shale rock samples under standard Brazilian disk test conditions. Data collected from the experiments are employed to determine the testing specimens' tensile strength and fracture toughness. To incorporate the effects of shale formation heterogeneity in the simulation of crack paths, fracture properties of the specimens are defined as spatially random fields. A computational strategy on the basis of stochastic finite element theory is developed that allows to incorporate the effects of heterogeneity of shale rocks on the fracture evolution. A parametric study has been carried out to better understand how anisotropy and heterogeneity of the mechanical properties affect both direction of cracks and rock strength.

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Section: Stochastic Approachmentioning

confidence: 99%

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

et al. 2018

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“…The spacing of the stress-induced fractures depends on the magnitude of rock stresses and the strength of rock, as well as the material heterogeneity (Cai 2008). On the one hand, the present studies on slabbing failure of hard rocks mainly concentrate on the description of slabbing phenomenon and how to control slabbing failure in situ (Dowding and Andersson 1986;Fang and Harrison 2002;Martin et al 1997). On the other hand, most studies are concerned with shear failure of hard rock (Bieniawski 1967a, b, c;Brady and Brown 2004;Lockner et al 1991;Mogi 2007;Moore and Lockner 1995;Savage et al 1996) except for a few studies on splitting failure (Holzhausen and Johnson 1979;Horii and Nemat-Nasser 1986;Li Chunlin 1995;Wong et al 2006) in the laboratory compression tests.…”

Section: Introductionmentioning

confidence: 99%

Influence of Sample Height-to-Width Ratios on Failure Mode for Rectangular Prism Samples of Hard Rock Loaded In Uniaxial Compression

2010

Rock Mech Rock Eng

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Surface-parallel slabbing is a failure mode often observed in highly stressed hard rocks in underground excavations. This paper presents the results of experimental studies on slabbing failure of hard rock with different sample height-to-width ratios. The main purpose of this study was to find out the condition to create slabbing failure under uniaxial compression and to determine the slabbing strength of hard rock in the laboratory. Uniaxial compression tests were carried out using five groups of granite specimens. The mechanical parameters of the sample rock, Iddefjord granite from Norway, were measured on the cylindrical and Brazilian disc specimens. The transition of the failure mode was studied using rectangular prism specimens. The initiation and the propagation of slabbing fractures in specimens were identified by examining the relationship among the applied stress, strain and the acoustic emission. The stress thresholds identified were compared to those reported by other authors for crack initiation and brittle failure. It is observed that the macro failure mode will be transformed from shear to slabbing when the height/width ratio is reduced to 0.5 in the prism specimens under uniaxial compression. Micro r 1 -parallel fractures initiate when the lateral strain departs from its linearity. Slabbing fractures are approximately parallel to the loading direction. Labotatory tests show that the slabbing strength (r sl ) of hard rock is about 60% of its uniaxial compression strength. It means that if the maximum tangential stress surrounding an underground excavation reaches about the slabbing threshold, slabbing fractures may take place on the boundary of the excavation. Therefore, the best way to stop or eliminate slabbing failure is to control the excavation boundary to avoid the big stress concentration, so that the maximum tangential stress could be under the slabbing threshold.

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“…sin u)/(1-sin u). According to the relationship of material parameters between Heok-Brown failure criterion and Mohr-Column failure criterion, the equivalent inner friction angle and cohesion of Mohr-Column failure criterion can be expressed with m and s of Heok-Brown failure criterion (Fang and Harrison 2002;Zhang et al 2015a):…”

Section: Elemental Constitutive Lawmentioning

confidence: 99%

Numerical modelling rock deformation subject to nitrogen cooling to study permeability evolution

Zhang

Wang

et al. 2015

Int J Coal Sci Technol

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How to model the permeability evolution of rock subjected to liquid nitrogen cooling is a key issue. This paper proposes a simple but practical method to study the permeability evolution of rocks subject to liquid nitrogen cooling. FLAC with FISH function was employed to numerically model the rock behavior under cooling. The enhanced permeability of the volumetric strain was defined, and the permeability was directly evaluated based on element's volumetric strain. Detailed procedures for implementing the evolution model of permeability in this paper were presented. A case study was carried out to simulate a coal bed where liquid nitrogen was injected in the bore hole. And a semi-submerged test of liquid nitrogen was performed. The method to model the permeability evolution of rocks subject to liquid nitrogen shock in this paper was proved to be right by the test results. This simulation results are discussed with the hope to provide some insight into understanding the nitrogen cooling practice.

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Development of a local degradation approach to the modelling of brittle fracture in heterogeneous rocks

Cited by 177 publications

References 32 publications

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

Influence of Sample Height-to-Width Ratios on Failure Mode for Rectangular Prism Samples of Hard Rock Loaded In Uniaxial Compression

Numerical modelling rock deformation subject to nitrogen cooling to study permeability evolution

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