Creep characteristics and constitutive model of coal under triaxial stress and gas pressure

Zhang, Liang; Li, Xiangchun; Gao, Jiaxing; An, Zhenxing; Yang, Xiaohan; Nie, Baisheng

doi:10.1002/ese3.532

Cited by 18 publications

(11 citation statements)

References 47 publications

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“…Assuming that the effect of effective stress is not considered, the adsorption expansion and desorption shrinkage deformation of the coal matrix by gas are elastic changes with reversibility; , thus, when the gas pressure in the coal reaches the desorption equilibrium state at the value of p , the strain in coal can be expressed in formula ε normalm ′ = 4 a p R T 9 V normalm E normalm [ ln false( 1 + b p 0 false) ‐ ln false( 1 + b p false) ] …”

Section: Model Constructionmentioning

confidence: 99%

Evolutionary Model and Experimental Validation of Gas-Bearing Coal Permeability under Negative Pressure Conditions

Shi

Zeng

et al. 2023

ACS Omega

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Coal bed methane drainage is the main approach to lower risks of coal seam while raising the efficiency in natural resource utilization. The negative pressure used for extraction in coal mines is largely determined empirically due to a lack of experimental research on how coal permeability changes under the combined influence of effective stress and negative pressure. This results in low gas extraction efficiency and concentration. In this paper, to study the effect law of complex stress and extraction on coal permeability during coal and gas co-mining, a test system was specially designed to determine the gas flow and coal permeability of coal samples under different stress paths and negative pressure conditions in the lab. The study analyzed the correlation between coal permeability, effective stress, and negative pressure and subsequently developed a permeability evolution model for gas-bearing coal under negative pressure conditions. The results showed that the permeability of coal increases with the increase in negative pressure and decreases with the increase in effective stress; the permeability of coal can be abruptly changed by changes in stress loading patterns; the established model of permeability evolution of gas-bearing coal can better reflect the correlation between permeability, effective stress, and negative pressure. The research outcomes offer a valuable theoretical foundation for the efficient extraction and utilization of methane in coal mines.

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Section: Model Constructionmentioning

confidence: 99%

Evolutionary Model and Experimental Validation of Gas-Bearing Coal Permeability under Negative Pressure Conditions

Shi

Zeng

et al. 2023

ACS Omega

Self Cite

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“…A series of creep experiments were carried out under gas pressure and triaxial compression. It was concluded that the creep deformation characteristics of coal were related to gas pressure and deviatoric stress, and the nonlinear model obtained could accurately describe the whole creep stage of coal [32]. Based on the porosity elasticity theory and uniaxial strain condition, Mathias studied the gas storage coefficient and permeability function of coalbed methane mining, established three ana-lytical models to describe the changes of porosity and permeability, and concluded that without considering the gas adsorption strain, only one of the porosity models can obtain the correct uniaxial strain storage coefficient equation [33].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Seepage Characteristics of Fractured Rock Mass under Different Stress Conditions

Fanfan

Niu

et al. 2021

Geofluids

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In order to obtain the mechanical behavior and permeability characteristics of coal under the coupling action of stress and seepage, permeability tests under different confining pressures in the process of deformation and destruction of briquette coal were carried out using the electrohydraulic servo system of rock mechanics. The stress-strain and permeability evolution curves of briquette coal during the whole deformation process were obtained. The mechanical behavior and permeability coefficient evolution response characteristics of briquette coal under stress-seepage coupling are well reflected. Research shows that stress-axial strain curve and the stress-circumferential strain curve have the same change trend, the hoop strain and axial strain effect on the permeability variation law of basic consistent, and the permeability coefficient with the increase of confining pressure and decreases, and the higher the confining pressure, the lower the permeability coefficient, the confining pressure increases rate under the same conditions, and the permeability coefficient corresponding to high confining pressure is far less than that corresponding to low confining pressure. The confining pressure influences the permeability of the briquette by affecting its dilatancy behavior. With the increase of the confining pressure, the permeability of the sample decreases, and the permeability coefficient decreases with the increase of the confining pressure at the initial stage, showing a logarithmic function. After failure, briquette samples show a power function change rule, and the greater the confining pressure is, the more obvious the permeability coefficient decreases.

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“…Mansouri et al [ 12 ] studied the creep properties of salt rocks under different gradient stresses, and based on creep curves and rock parameters, obtained a steady-state creep rate constitutive equation, established the relationship between the microscopic and macroscopic deformation of salt rocks, and derived the plastic constitutive equation of salt rocks, which can reflect the deformation mechanism of plasticity and the creep of salt rocks. Zhang et al [ 13 ] studied the coupling effect of triaxial stress and gas pressure on coal, considered effective stress in the Nishihara model, and conducted an in-depth analysis of the creep stage of coal and rock. Numerous scholars from teams such as Liu et al [ 14 ], Lin et al [ 15 ], Wu et al [ 16 ], Gutiérrez-Ch et al [ 17 ], Lyu et al [ 18 ], and Zhang et al [ 19 ] have made more research results on uniaxial and triaxial compression creep in soft rocks such as tuffs, shales, siltstones, salts, weathered sandstones, and coal bodies.…”

Section: Introductionmentioning

confidence: 99%

Research on the Creep Model of Deep Coal Roadway and Its Numerical Simulation Reproduction

Zhang

Wang

Ding

2022

IJERPH

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The long-term stability of coal mine roadway engineering is critical to the safe mining of coal resources and the protection of the surface environment. In this paper, the creep test of coal samples in coal roadway was carried out by multi-stage constant load method, and the test results showed that when the stress level was low, the creep curve had a attenuated stage and a steady-state stage, and the steady-state creep rate tended to increase with the increase in the stress level; When the stress level was higher than the yield stress, the creep rate curve appeared to have an acceleration stage after the steady-state stage. The instability failure mode of the coal sample was mainly shear failure with local tension failure. For this, a New Fractional-order Nonlinear Viscoelastic-plastic Rheological Model (NFNVRM) was established by introducing Abel elements and Nonlinear elements, and the constitutive equation of the model was deduced. The new model can fully reflect the stable decay stage and accelerated rheological stages of coal samples, and the parameter identification curve was consistent with the experimental results, which verifies the correctness and reasonableness of the NFNVRM. Meanwhile, based on the FLAC3D secondary development interface, the constitutive equations of the NFNVRM were written into the software to obtain new Dynamic Link Library (DLL) files. The simulation results were consistent with the experimental results when the DLL file was called. Finally, the NFNVRM.dll was applied to predict the surrounding rock deformation of an S mine. The study’s findings offer suggestions for environmental protection.

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Creep characteristics and constitutive model of coal under triaxial stress and gas pressure

Cited by 18 publications

References 47 publications

Evolutionary Model and Experimental Validation of Gas-Bearing Coal Permeability under Negative Pressure Conditions

Evolutionary Model and Experimental Validation of Gas-Bearing Coal Permeability under Negative Pressure Conditions

Experimental Study on Seepage Characteristics of Fractured Rock Mass under Different Stress Conditions

Research on the Creep Model of Deep Coal Roadway and Its Numerical Simulation Reproduction

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