Numerical studies of the influence of microstructure on rock failure in uniaxial compression — Part I: effect of heterogeneity

Tang, Chun An; Liu, H; Lee, P.K.K; Tsui, Y; Tham, L.G.

doi:10.1016/s1365-1609(99)00121-5

Cited by 489 publications

(230 citation statements)

References 13 publications

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“…The number of AE occurrences are commonly increased just before solids is destructed: the stress of rock reach to uniaxial compressive strength in uniaxial compressive test. AE monitoring is, therefore, used in the field of rock mechanics, concrete, and mining to predict the damage and the failure of brittle materials because they reach structural failure by accumulating microfracture [18][19][20][21][22]. As many AE activities can be detected attributable to thermal stress during UCG process [23], it is also useful to estimate the progress of gasification process and special events such as collapse of coal in the cavity and extensive propagation of gasification zone.…”

Section: Methodsmentioning

confidence: 99%

Effect of Injection Flow Rate on Product Gas Quality in Underground Coal Gasification (UCG) Based on Laboratory Scale Experiment: Development of Co-Axial UCG System

Hamanaka

Itakura

et al. 2017

Energies

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Underground coal gasification (UCG) is a technique to recover coal energy without mining by converting coal into a valuable gas. Model UCG experiments on a laboratory scale were carried out under a low flow rate (6~12 L/min) and a high flow rate (15~30 L/min) with a constant oxygen concentration. During the experiments, the coal temperature was higher and the fracturing events were more active under the high flow rate. Additionally, the gasification efficiency, which means the conversion efficiency of the gasified coal to the product gas, was 71.22% in the low flow rate and 82.42% in the high flow rate. These results suggest that the energy recovery rate with the UCG process can be improved by the increase of the reaction temperature and the promotion of the gasification area.

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Section: Methodsmentioning

confidence: 99%

Effect of Injection Flow Rate on Product Gas Quality in Underground Coal Gasification (UCG) Based on Laboratory Scale Experiment: Development of Co-Axial UCG System

Hamanaka

Itakura

et al. 2017

Energies

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“…Grain crushability can be included in the modelling procedure using discrete element analysis [18,19]. Discrete element models can mimic the macroscopic behaviour of real including elasticity, anisotropic damage, post-peak softening [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Shear banding in drained and undrained triaxial tests on a saturated sandstone: Porosity and permeability evolution

Sulem

Ouffroukh

2006

International Journal of Rock Mechanics and Mining Sciences

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To cite this version:Jean Sulem, Hichem Ouffroukh. Shear-banding in drained and undrained triaxial tests on a saturated sandstone ; porosity and permeability evolution.. AbstractDetailed analysis of shear band formation and shear band microstructure formed in drained and undrained triaxial tests on Fontainebleau sandstone is presented. It is shown that under globally undrained conditions, local fluid exchanges inside the sample occur at shear banding resulting into an heterogeneous damage pattern along the shear band. At high confinement, pore pressure generation inside the band leads locally to fluidisation of the crushed material which results into the formation of connected channels in the heart of the band. Image processing analysis is used for evaluation of porosity inside the shear band and estimation of the permeability is performed using the Walsh and Brace [26] model. It is shown that, porosity increase as observed in the band at low confining pressure and porosity decrease as observed at high confining pressure are both accompanied by a reduction of permeability inside the shear band due to the increase of tortuosity and specific surface. However, this permeability reduction is much more important at high confining pressure and can reach values three orders of magnitude smaller than the permeability of the intact material.

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“…where F is an elemental strength parameter or stress level, and because the strain strength theory is adopted here, it denotes strain; m and F 0 are the distribution parameters; and P(F) is the percentage of damaged ones out of the total number of the microcells in the rock [8].…”

Section: Establishment Of the Damage Statistical Constitutive Model Bmentioning

confidence: 99%

“…But the shortcoming in the existing studies is that they all ignore the effect of the mesoscopic flaw on the jointed rock mass mechanical behavior. The existing results [8,9] have also proved that the stochastic microcracks would cause the isotropic damage in rock mass, which caused the strength reduction and stiffness deterioration. Therefore, it is very necessary to comprehensively consider the co-effect of these two kinds of flaws on the jointed rock mass mechanical behavior.…”

Section: Introductionmentioning

confidence: 97%

A Damage Constitutive Model for Rock Mass with Nonpersistently Closed Joints Under Uniaxial Compression

Liu

Zhang

2015

Arab J Sci Eng

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As part of the rock mass, both the macroscopic flaws such as joints and the mesoscopic flaws such as microcracks affect the strength and the deformational behavior of rock mass. Existing models can either handle any one of them alone, and a model which can consider the co-effect of these two kinds of flaws on rock mass mechanical behavior is not yet available. This study focusses on rock mass with nonpersistently closed joints and establishes a new damage constitutive model for it. Firstly, the damage model for the intact rock which contains only the mesoscopic flaws is introduced. Second, the expression of the macroscopic damage variable (tensor) which can consider the joint geometrical and mechanical properties at the same time is obtained based on the energy principle and fracture theory. Third, the damage variable based on coupling the macroscopic and mesoscopic flaws is deduced based on Lemaitre strain equivalence hypothesis, and then the corresponding damage constitutive model for rock mass with nonpersistently closed joints under uniaxial compression is set up. Finally, the test data for the intact rock under uniaxial compression are adopted to validate the proposed model. A series of calculation examples verify that the proposed model is capable of presenting the

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Numerical studies of the influence of microstructure on rock failure in uniaxial compression — Part I: effect of heterogeneity

Cited by 489 publications

References 13 publications

Effect of Injection Flow Rate on Product Gas Quality in Underground Coal Gasification (UCG) Based on Laboratory Scale Experiment: Development of Co-Axial UCG System

Effect of Injection Flow Rate on Product Gas Quality in Underground Coal Gasification (UCG) Based on Laboratory Scale Experiment: Development of Co-Axial UCG System

Shear banding in drained and undrained triaxial tests on a saturated sandstone: Porosity and permeability evolution

A Damage Constitutive Model for Rock Mass with Nonpersistently Closed Joints Under Uniaxial Compression

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