Experimental Study on Mechanical and Damage Evolution Characteristics of Coal during True Triaxial Cyclic Loading and Unloading

Jiang, Chongyang; Wang, Lianguo; Ding, Ke; Wang, Shuai; Ren, Bo; Guo, Jiaxing

doi:10.3390/ma16062384

Cited by 3 publications

(1 citation statement)

References 30 publications

(32 reference statements)

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“…Few investigations on its mechanical strength have been reported, particularly during “unloading” process. Most existing research has primarily focused on the mechanical properties and failure morphology of hard rocks using different loading and unloading paths, with fewer studies considering the deformation and comprehensive effects of different loading and unloading paths on soft rocks [ 22 , 23 , 24 ]. Therefore, in this paper, silt-like mudstone specimens, composed of gypsum, barite powder, and nanomaterials, were used to conduct triaxial tests using different unloading paths so that we could investigate the influence of different initial confining pressures and deviatoric stresses on the strength and failure characteristics of silty mudstone.…”

Section: Introductionmentioning

confidence: 99%

Study on the Strength and Failure Characteristics of Silty Mudstone Using Different Unloading Paths

Wang

Zhang

et al. 2023

Materials

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To investigate the strength and failure characteristics of silty mudstone using different stress paths, silt-like mudstone specimens were subjected to triaxial unloading tests. The results indicate the following. (1) When subjected to equivalent initial deviator stress levels and differing confining pressures, the peak stress, residual stress, and elastic modulus, exhibited during unloading, increased concordantly with greater initial confining pressure. Both the peak strain and residual strain increased with rising initial confining pressure. The increase in peak strain and residual strain initially decelerated, then noticeably increased, before ultimately decreasing again. Additionally, the unloading failure time and strain rate demonstrated a negative correlation as the confining pressure increased. (2) Under different initial deviatoric stress conditions, the peak stress, residual stress, and residual strain, under unloading confining pressure conditions, decreased as the initial deviatoric stress levels elevated. Conversely, the peak strain and elastic modulus initially increased, then decreased under increasing initial deviatoric stress conditions. The unloading failure time and strain rate were both observed to decrease as the initial deviatoric stress levels increased. (3) Utilizing the Mohr stress circle enabled the characterization of the shear strength variation in the specimens during the unloading process. The cohesion and internal friction angle remained relatively consistent across the different unloading stress paths appraised, with cohesion being greater in path I versus path II, whereas the internal friction angle exhibited an inverse relationship. (4) The specimen failed during unloading due to lateral expansion caused by unloading confining pressure and collapse failure. The failure fracture surfaces predominantly manifested shear failure morphologies.

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Section: Introductionmentioning

confidence: 99%

Study on the Strength and Failure Characteristics of Silty Mudstone Using Different Unloading Paths

Wang

Zhang

et al. 2023

Materials

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Evolution of mechanical parameters of Shuangjiangkou granite under different loading cycles and stress paths

Gu,

Feng,

Kong

et al. 2024

Journal of Rock Mechanics and Geotechnical Engineering

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Burst Failure Characteristics and Energy Evolution Law of Coal with Prefabricated Cracks at Different Angles

Zhang,

Han,

Chen

et al. 2024

Shock and Vibration

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In order to study the influence of fissures on the burst tendency of coal, the test and numerical simulation of the burst tendency of coal with different burst angles were carried out. The evolution law of the burst tendency index of coal under the influence of burst angle was analyzed, and the mechanism of energy storage and release of coal under the influence of fissure angle was revealed. The results show that compared with the specimens without prefabricated cracks, the uniaxial compressive strength of the specimens with 0° cracks is reduced by 48.4%, the dynamic failure time is increased by 279.4%, the burst energy index is reduced by 54%, and the burst energy velocity index is reduced by 87.9%. After that, with the increase of prefabricated crack angle, the uniaxial compressive strength of coal increases gradually, the dynamic failure time decreases gradually, the burst energy index increases gradually, and the burst energy velocity index increases gradually. That is to say, the larger the crack angle contained in the coal body, the stronger the burst tendency of the coal body, but it is still lower than that of the complete coal body. With the increase of prefabricated crack angle, the proportion of prepeak elastic energy of coal body increases, the less energy dissipation in the whole loading process of coal body, and the faster energy release rate during failure. The research results can provide some theoretical support for the prevention and control of rock burst disaster.

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Experimental Study on Mechanical and Damage Evolution Characteristics of Coal during True Triaxial Cyclic Loading and Unloading

Cited by 3 publications

References 30 publications

Study on the Strength and Failure Characteristics of Silty Mudstone Using Different Unloading Paths

Study on the Strength and Failure Characteristics of Silty Mudstone Using Different Unloading Paths

Evolution of mechanical parameters of Shuangjiangkou granite under different loading cycles and stress paths

Burst Failure Characteristics and Energy Evolution Law of Coal with Prefabricated Cracks at Different Angles

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