Numerical Research on Energy Evolution and Burst Behavior of Unloading Coal–Rock Composite Structures

Yin, Yanchun; Tan, Yunliang; Lu, Ying; Zhang, Yubao

doi:10.1007/s10706-018-0609-5

Cited by 10 publications

(5 citation statements)

References 30 publications

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“…e results show that the gas seepage characteristics and charge induction law are closely related to the deformation and damage process of coal and rock during the unloading process of confining pressure. To research the evolution of energy stored in the composite coal-rock structure and coal fragments burst characteristics, lateral pressure unloading numerical tests of composite coalrock models with different Young's modulus were carried by PFC2D software in reference [27]. Reference [28] established the coal-rock composite models with different inclined angles by using particle flow code, and the impact instability characteristics after unloading were analyzed.…”

Section: Introductionmentioning

confidence: 99%

Multifield Coupling Mechanism of Unloading Deformation and Fracture of Composite Coal‐Rock

Yang

et al. 2021

Shock and Vibration

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The deformation and fracture evolution of coal and rock under unloading are prone to sudden instability or dynamic damage. To solve the problem, this paper combines interdisciplinary theories such as damage mechanics and electromagnetic field theory. The mathematical model of multiphysics coupling during loading and unloading of composite coal-rock is deduced. In addition, numerical simulations along with experimental verification are carried out to study multi-physical field variation and coupling mechanisms. The composite coal-rock deforms and ruptures under unloading, and the brittle failure of the rock body becomes more sudden when the confining pressure is unloaded. Macroscopically, many microcracks are generated and expanded during the loading and unloading of composite coal-rock. Microscopically, the internal old molecular chains are broken to form new molecular chains by the force. Simulation results show that, during the loading and unloading process, the three physical fields of the composite coal-rock all change regularly. During the unloading of coal and rock, there is a transition period in which the temperature increases sharply and reaches the maximum. Then, the temperature decreases due to the gradual decrease of its bearing capacity. Besides, the electromagnetic field is strongest on the surface of the coal body, and its propagation in the air decays exponentially. There are small fluctuations that appear at the junction of the coal body and the air. The experimental results show that the internal infrared radiation temperature of the composite coal-rock decreases during the initial stage of loading and unloading due to the discharge of internal gas. In the first stage of “loading and unloading,” it increases with the increase in stress, and the temperature suddenly increases in a short time after unloading. The electromagnetic radiation fluctuates in small amplitudes at the initial stage. When the stress is about to reach the peak, the electromagnetic radiation intensity increases and reaches the peak suddenly. Then, the coal-rock ruptures, the stress decreases, and the electromagnetic radiation weakens. The experiment and simulation results are consistent. The multiphysics coupling model is used to study the characteristics of coal and rock unloading under complex conditions, providing a theoretical basis and new method for the prediction and forecast of coal and rock mining dynamic disasters.

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Section: Introductionmentioning

confidence: 99%

Multifield Coupling Mechanism of Unloading Deformation and Fracture of Composite Coal‐Rock

Yang

et al. 2021

Shock and Vibration

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“…The particle flow code (PFC) based on the discrete element method has emerged as a remarkable tool for examining the fracturing mechanisms of rocks under unloading conditions from a microscopic viewpoint [30,31]. Researchers such as Li et al [32], Xiong et al [33], and Yin et al [34] have utilized PFC 2D to investigate the macroscopic mechanical behavior, crack propagation, and evolution of various energy indicators in unloaded rocks, highlighting the impact of unloading rates on microscopic structural damage and fracturing. Furthermore, studies conducted by Zhang [35], Zheng et al [36], and Uxia et al [37] using PFC 3D have explored the initiation, propagation, connectivity, and spatial distribution of microcracks in rocks during unloading, revealing that the unloading effect contributes to post-peak damage and failure in rocks.…”

Section: Introductionmentioning

confidence: 99%

Effect of Confining Pressure on the Macro- and Microscopic Mechanisms of Diorite under Triaxial Unloading Conditions

Duan,

Yang,

2024

Buildings

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In this study, the response mechanism between macro- and microscales of deep hard-rock diorite is investigated under loading and unloading conditions. Moreover, the statistical theory is combined with particle flow code simulations to establish a correlation between unloading rates observed in laboratory experiments and numerical simulations. Subsequent numerical tests under varying confining pressures are conducted to examine the macroscopic mechanical properties and the evolution of particle velocity, displacement, contact force chain failures, and microcracks in both axial and radial directions of the numerical rock samples during the loading and unloading phases. The findings indicate that the confining pressure strength curve displays an instantaneous fluctuation response during unloading, which intensifies with higher initial confining pressures. This suggests that rock sample damage progresses in multiple stages of expansion and penetration. The study also reveals that with increased initial confining pressure, there is a decrease in particle velocity along the unloading direction and an increase in particle displacement and the number of contact force chain failures, indicating more severe radial expansion of the rock sample. Furthermore, microcracks predominantly accumulate near the unloading surface, and their total number escalates with rising confining pressure, suggesting that higher confining pressures promote the development and expansion of internal microcracks.

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“…They analyzed the damage process from the energy conversion perspective of the coal‐rock structural body. Yin et al 14 studied coal fragments' energy evolution and distribution characteristics in the seam‐overlying strata. Li et al 15 analyzed the variation characteristic of energy, damage variables, and failure of the coal‐rock structural body with different height ratios under the uniaxial loading.…”

Section: Introductionmentioning

confidence: 99%

Effect of confining pressure strength on the characteristics of energy evolution and fatigue fracture of the coal‐rock structural body

Li,

Yue,

et al. 2023

Fatigue Fract Eng Mat Struct

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The stability of coal seam‐overlying strata is significant to the safety of coal mines. The coal‐rock height ratio and confining pressure strength affect the stability of coal seam‐overlying strata. The research purpose of this paper is to obtain the effects of confining pressure and coal‐rock height ratio on the mechanical properties, energy evolution characteristics, and damage variables of structural body through the uniaxial loading, uniaxial cyclic loading, and triaxial cyclic loading experiment. Based on the evolution characteristics of the energy, the concept of energy dissipation ratio is put forward, and the effect of height ratio and confining strength on the energy dissipation ratio are compared and analyzed. The research results of this paper can provide theoretical reference for exploring the stress and energy evolution of coal seam‐overlying strata during chamber excavation and working face mining.

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Numerical Research on Energy Evolution and Burst Behavior of Unloading Coal–Rock Composite Structures

Cited by 10 publications

References 30 publications

Multifield Coupling Mechanism of Unloading Deformation and Fracture of Composite Coal‐Rock

Multifield Coupling Mechanism of Unloading Deformation and Fracture of Composite Coal‐Rock

Effect of Confining Pressure on the Macro- and Microscopic Mechanisms of Diorite under Triaxial Unloading Conditions

Effect of confining pressure strength on the characteristics of energy evolution and fatigue fracture of the coal‐rock structural body

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