Mechanical Properties and Failure Behavior of Dry and Water-Saturated Anisotropic Coal Under True-Triaxial Loading Conditions

Liu, Yubing; Yin, Guangzhi; Li, Minghui; Zhang, Dongming; Huang, Gun; Liu, Peng; Liu, Chao; Zhao, Hongbao; Yu, Beichen

doi:10.1007/s00603-019-02035-9

Cited by 52 publications

(22 citation statements)

References 61 publications

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“…According to the geological structure characteristics of coal seam, the raw cubic coal samples were prepared in the orthogonal fracture directions in Liu's research [49]. The orthogonal fracture directions were bedding plane direction (BD), face cleat plane direction (FD), and butt cleat plane direction (UD), respectively.…”

Section: Orthogonal Anisotropic Coal Under True Triaxial Stressmentioning

confidence: 99%

“…Based on Liu's research [49], the damage evolution of orthotropic coal samples drilled in different directions under true triaxial loading is analyzed by the SDAR model. Figure 6 demonstrates the evolution of coal samples prepared in each direction (BD, FD, and UD) under different stress paths.…”

Section: Orthogonal Anisotropic Coal Under True Triaxial Stressmentioning

confidence: 99%

“…The sensitivity analysis was based on the test in BD under stress path 1 (σ 2 = 20MPa, σ 3 = 10MPa) of Liu's research [49]. Sensitivity analysis is conducted from two aspects: mechanical parameters and model parameters.…”

Section: Sensitivity Study Of Parametersmentioning

confidence: 99%

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A Statistical Damage Constitutive Model of Anisotropic Rock: Development and Validation

et al. 2021

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The damage constitutive model is of great significance to research the stress-strain relationship and damage evolution of rock under loading in engineering. In order to investigate the effect of anisotropic characteristic on the stress-strain relationship and damage evolution, a statistical damage constitutive model of anisotropic rock under true triaxial condition was developed. In this study, the plane which existed perpendicular to the coordinate axis was extracted from representative volume element (RVE) of rock. The extracted plane was assumed to be composed of abundant mesoscopic elements whose failure strength satisfied the Weibull distribution. According to the number of failure elements on the plane in each direction under loading, the anisotropic damage variable was established based on the proposed concept of areal damage. A statistical damage constitutive model of anisotropic rock was developed by using strain equivalent hypothesis and generalized Hooke constitutive model. Subsequently, the parameters in the anisotropic damage constitutive model were determined by the method of total differential. Thus, the damage evolution of anisotropic rock under various stress conditions can be conveniently evaluated by the anisotropic damage model. The model was validated based on the tests of rocks under the stress conditions of conventional triaxial and true triaxial, respectively. Moreover, for the purpose of studying the influence of parameters on the model, sensitivity analyses of mechanical parameters and model parameters were carried out. The results of statistical damage constitutive clearly demonstrate the stress-strain and damage evolution of anisotropic rock under various stress conditions.

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Section: Orthogonal Anisotropic Coal Under True Triaxial Stressmentioning

confidence: 99%

Section: Orthogonal Anisotropic Coal Under True Triaxial Stressmentioning

confidence: 99%

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A Statistical Damage Constitutive Model of Anisotropic Rock: Development and Validation

et al. 2021

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“…In general, the initiation of tensile cracks in rock materials mostly has high AF values and low RA values, whereas shear cracks have the characteristics of high RA values and low AF values. As shown in Figure 8, based on the studies of Liu [10], Yao [11], Ohtsu [23], and He [28], RA-AF correlation analysis was used to classify the cracking mode of the coal samples (AF:RA = 1). Accordingly, the classification results of the cracking mode during triaxial unloading of typical coal samples at different depths are shown in Figure 9.…”

Section: Crack Classification Based On Ae Parametersmentioning

confidence: 99%

“…For example, Zhang et al [9] investigated the failure mechanism of coal pillars under uniaxial compression by analyzing the evolution of the AE energy release. Liu et al [10] studied the difference in the failure behavior of dry coal and water-containing coal under true triaxial stress conditions through a combination of AE characteristic parameters. Yao et al [11] studied the differences in crack propagation and failure modes of coal samples with different water contents under uniaxial compression.…”

Section: Introductionmentioning

confidence: 99%

Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Zhang

Gao

et al. 2020

Energies

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The depth effect of coal mechanical behavior seriously affects the safety and efficiency of deep coal mining. To explore the differences in failure behavior and damage characteristics of coal masses at different depths during the coal mining process, based on the consideration of in situ stress environment, physical properties, and mining disturbance of coal seams, triaxial unloading experiments with acoustic emission (AE) monitoring were conducted on coal samples at four different depths taken from the Pingdingshan coal mine area. The results showed that the AE activity of deep coal was more concentrated, and the cumulative AE energy of coal increased with increasing depth. The cumulative AE energy of the 1050-m coal sample was 69 times that of the 300-m coal sample. The b value representing the microcrack scale decreased with increasing depth, and the rupture degree of deep coal increased. The cracking mode of coal was classified and the failure behavior was analyzed. The cumulative tensile crack percentage of coal increased with increasing depth, and the tensile–shear composite failure occurred in the 300-m coal sample, whereas significant tensile failure occurred in the 1050-m coal sample. In addition, the damage evolution process of coal was divided into three stages, and the characteristic stress of coal was obtained. The ratio of crack initiation stress (σci) to peak stress (σc) increased with increasing depth, and the damage evolution process of deep coal was more rapid. The research results can provide useful guidance for disaster prevention and evaluation of surrounding rock stability during deep coal resource mining in the Pingdingshan coal mine area.

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Effect of water on the damage and energy dissipation feature of coal under uniaxial cyclic loading–unloading condition

Song,

Zhao,

et al. 2023

Energy Science & Engineering

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To gain insight into the reduction mechanism of water on the dynamic destabilization failure character of coal under mining disturbance conditions, the effect of water on the damage and energy dissipation feature of coal was investigated via cyclic uniaxial compressive loading–unloading test, acoustic emission (AE) monitoring technology, and theoretical analysis. It manifests that the softening effect of water on the mechanical properties of coal is still remarkable, lower uniaxial compressive strength and elastic modulus, while greater axial strain and higher Poisson's ratio are observed under the cyclic loading–unloading condition. Water‐saturated specimens dissipate more energy during the cyclic loading–unloading process, which reduces the proportion of input energy accumulated in the coal mass, thus lowering the burst proneness of coal. A greater amount of damage generates in air‐dried specimens than that in water‐saturated specimens at the first cyclic loading–unloading cycle, while lower damage increments are observed in the following cycles. This may be the reason for the minimal energy dissipation of air‐dried specimens in the following cycles. The elastic modulus behaves logarithmically versus the increasing cyclic loading–unloading cycle counts. The energy dissipated due to the damage evolution and plastic deformation of coal specimens positively correlates with the energy released by AE activities, the AE energy in air‐dried specimens has a greater concentration around the peak axial stress and a stronger correlation with the dissipated energy. The cumulative AE energy and energy dissipation density are linearly correlated during the cyclic loading–unloading process, which indicates a possibility in estimating the damage evolution and the dynamic failure risk of coal via cumulative AE energy, under the cyclic loading–unloading condition.

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Mechanical Properties and Failure Behavior of Dry and Water-Saturated Anisotropic Coal Under True-Triaxial Loading Conditions

Cited by 52 publications

References 61 publications

A Statistical Damage Constitutive Model of Anisotropic Rock: Development and Validation

A Statistical Damage Constitutive Model of Anisotropic Rock: Development and Validation

Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Effect of water on the damage and energy dissipation feature of coal under uniaxial cyclic loading–unloading condition

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