Creep properties of intact and fractured muddy siltstone

Omar, Husaini; Stace, Rod

doi:10.1016/j.ijrmms.2018.03.006

Cited by 57 publications

(24 citation statements)

References 25 publications

(34 reference statements)

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“…62,63 The calculations and fitting results are as shown in Figure 7 and Table 2. 62,63 The calculations and fitting results are as shown in Figure 7 and Table 2.…”

Section: Model Validationmentioning

confidence: 99%

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

Zhang

Gao

et al. 2019

Energy Science & Engineering

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Creep behavior is one of the most important mechanical behaviors of coal. In the present study, we systematically carried out a series of creep experiments of briquette samples under triaxial compression and gas pressure. The experimental results showed that the creep deformation characteristics of coal were related to deviatoric stress and gas pressure. The accelerating creep stage initiated when the deviatoric stress reached or exceeded the yield stress until failure took place. In contrast, when the deviatoric stress was less than the yield strength, only transient and steady creep stage occurred. Besides, gas pressure played a positive role in the creep process of coal. The axial strain of coal slightly increased with gas pressure (range from 0.13 to 0.40 MPa) when the effective triaxial stress remained constant. For example, in the steady creep stage (σ 1 = 9 MPa, p = 0.13 MPa), the axial strain of sample S 1 is 2.710% and that of sample S 2 is 3.361%, that is, coal samples with high gas pressure have higher axial strain. Moreover, gas pressure has two main effects on the mechanical behavior of coal. One is that the coal adsorbs gas molecules resulting in swelling strain and swelling stress, and the other is that the gas pressure may compress the coal particles. Considering the swelling stress and gas pressure, we intensively studied the effective stress formula of coal containing gas. Then, the effective stress was taken into consideration in the nonlinear Nishihara creep model. Furthermore, the tertiary creep factor n was introduced in the nonlinear model to control the creep deformation evolution with time so that the nonlinear model could accurately describe the full creep stage of coal. In contrast, due to the lack of such a controlling parameter, the Nishihara model failed to reproduce the accelerating creep stage. K E Y W O R D Scoal, creep model, effective stress, gas pressure, swelling stress, triaxial compression | INTRODUCTIONCreep behavior is one of the fundamental mechanical properties of coal or rock, associated with the stability of many buildings and underground structures in mining and rock engineering, such as roadways, tunnels, and dams. It is important to have a precise understanding of the creep or timedependent behavior of coal or rock, which may prevent coal 502 | ZHANG et Al. Highlights• The coupling effect of triaxial stress and gas pressure on coal was investigated. • The gas pressure played a positive role in the creep process of coal. • The effective stress of gas-filled coal was intensively studied. • The effective stress was considered in the nonlinear Nishihara creep model of coal, which could accurately reproduce the three creep stages, especially the accelerating creep stage.How to cite this article: Zhang L, Li X-C, Gao J-X, An Z-X, Yang X-H, Nie B-S. Creep characteristics and constitutive model of coal under triaxial stress and gas pressure. Energy Sci Eng. 2020;8:501-514. https ://doi.

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“…62,63 The calculations and fitting results are as shown in Figure 7 and Table 2. 62,63 The calculations and fitting results are as shown in Figure 7 and Table 2.…”

Section: Model Validationmentioning

confidence: 99%

“…In the current study, the creep parameters were determined through a nonlinear least squares regression analysis using MATLAB (MathWorks). 62,63 The calculations and fitting results are as shown in Figure 7 and Table 2.…”

Section: Model Validationmentioning

confidence: 99%

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

Zhang

Gao

et al. 2019

Energy Science & Engineering

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“…Creep property is an important mechanical property of rocks and the main factor affecting long-term stability of geotechnical engineering [1][2][3][4][5][6][7]. Obtaining the stress and deformation characteristics of rock masses from the perspective and method of their rheology is consistent with reality [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Improved Nonlinear Nishihara Shear Creep Model with Variable Parameters for Rock-Like Materials

Lin

Zhang

Wang

et al. 2020

Advances in Civil Engineering

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Creep property is an important mechanical property of rocks. Given the complexity of rock masses, mechanical parameters change with time in the creep process. In this work, a nonlinear function for describing the time-dependent change of parameters was introduced and an improved variable-parameter nonlinear Nishihara shear creep model of rocks was established. By creating rock-like materials, the mechanical properties of rocks under the shear creep test condition were studied, and the deformation characteristics and long-term shear strength of rocks during creep were analyzed. The material parameters of the model were identified using the creep test results. Comparison of the model’s calculated values and experimental data indicated that the model can describe the creep characteristics of rocks well, thus proving the correctness and rationality of the improved model. During shear creep, the mechanical properties of rocks have an aging effect and show hardening characteristics under low shear stress. Furthermore, according to the fact that Gk of the nonlinear model can characterize the creep deformation resistance, a method to determine the long-term shear strength is proposed.

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“…However, the strain of the jointed sample is somewhat larger than that of intact rock. Hamza and Stace [23] investigated the creep behavior of intact and fractured rock samples. A larger creep deformation, larger steady-state creep rate, and smaller creep parameters were found for the fractured rock.…”

Section: Introductionmentioning

confidence: 99%

“…A series of creep tests on intact samples were carried out to investigate the influence of temperature and stress condition on the creep behavior of Beishan granite [25]. Considering that the time-dependent behavior of cracked rock represents an important condition of rock mass [23], the objective of the experiments in this study is to investigate the creep characteristics of cracked Beishan granite. A series of multistage creep tests under different confining pressures were conducted on cracked samples.…”

Section: Introductionmentioning

confidence: 99%

Deformation and Acoustic Emission Characteristics of Cracked Granite during Creep

Wang

Xie

Liu

2020

Advances in Materials Science and Engineering

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A series of multistage creep tests under different confining pressures with acoustic emission monitoring have been performed to investigate the deformation characteristic and failure process of cracked granite during creep. The critical axial strain of cracked sample showed an increasing tendency with the increase of confining pressure. In contrast, critical lateral strain experienced a process of descending first at low confinement and then remaining nearly constant at high confinement. Compared with loading-cracked specimen, smaller critical axial strain, greater critical lateral strain, and higher lateral creep strain rate were found for unloading-cracked specimen. Based on the spatial and temporal distribution of acoustic emission events, the cracking process during creep was analysed. The AE events with high energy are mainly concentrated at the final fracture area of the specimen. The higher the confining pressure, the more the AE events with low energy. Compared with the loading-cracked specimen, the percentage of AE events with high energy is relatively small for the unloading-cracked specimen.

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Creep properties of intact and fractured muddy siltstone

Cited by 57 publications

References 25 publications

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

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

Improved Nonlinear Nishihara Shear Creep Model with Variable Parameters for Rock-Like Materials

Deformation and Acoustic Emission Characteristics of Cracked Granite during Creep

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