A Nonlinear Creep Damage Coupled Model for Rock Considering the Effect of Initial Damage

Hou, Rongbin; Zhang, Kai; Tao, Jing; Xue, Xinran; Chen, Yanlong

doi:10.1007/s00603-018-1626-7

Cited by 123 publications

(46 citation statements)

References 28 publications

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“…Some scholars did take damage into account in the creep model they have established. However, they tend to assume that the damage appears only in the accelerated creep stage, while ignoring other damage (Hou et al., 2018; Huang and Shao, 2012; Shi et al., 2019). In this paper, first the rocks are unloaded at different stages to prepare the rock samples with different initial damage.…”

Section: Introductionmentioning

confidence: 99%

An improved nonlinear damage model of rocks considering initial damage and damage evolution

Feng

Qiao

Niu

et al. 2020

International Journal of Damage Mechanics

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The experimental results show that the creep properties of the rocks are affected by the initial damage, and the damage evolution also has a significant impact on the time-dependent properties of the rocks during the creep. However, the effects of the initial damage and the damage evolution are seldom considered in the current study of the rocks' creep models. In this paper, a new nonlinear creep damage model is proposed based on the multistage creep test results of the sandstones with different damage degrees. The new nonlinear creep damage model is improved based on the Nishihara model. The influences of the initial damage and the damage evolution on the components in the Nishihara model are considered. The creep damage model can not only describe the changes in three creep stages, namely, the primary creep, the secondary creep, and the tertiary creep, but also reflect the influence of the initial damage and the damage evolution on creep failure. The nonlinear least squares method is used to determine the parameters in the nonlinear creep damage model. The consistency between the experimental data and the predicted results indicates the applicability of the nonlinear damage model to accurately predict the creep deformation of the rocks with initial damage.

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Section: Introductionmentioning

confidence: 99%

An improved nonlinear damage model of rocks considering initial damage and damage evolution

Feng

Qiao

Niu

et al. 2020

International Journal of Damage Mechanics

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“…Lemaitre [22] and Du et al [23] described the deterioration and damage degree of mechanical properties of coal samples in cyclic loading and unloading test by the degradation rate of elastic modulus of coal samples. Hou et al [24] proposed a modified elastic modulus method to define the damage of rock samples in the uniaxial test. Besides, Chai et al [25] performed the variable angle shear compression test of mudstone samples under natural conditions based on the nonlinear fractal theory, and learned the evolution law of cracks and the fractal characteristics of broken blocks under compression and shear loads.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Damage in Lignite under Combined Cyclic Compression and Shear Loading

Bai

Chen

et al. 2020

Sustainability

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In this paper, uniaxial cyclic compression and shear test was carried out for lignite samples. The effects of inclination angle (θ) and upper limit of cyclic stress (σmax) on mechanical properties of coal samples were analyzed, and the damage variables of coal samples were studied based on energy dissipation theory. The results show that the uniaxial compressive strength (UCS) of coal samples after uniaxial cyclic compression and shear tests decreases with the increase of the upper limit of cyclic stress and inclination angle. The shear stress component generated by the increase of inclination angle can effectively reduce the UCS and increase the damage degree of coal samples. With the increase of inclination angle, the failure mode of coal samples is changed from tensile failure (θ = 0°), the combined tensile failure and shear failure (θ = 5°) to shear failure (θ = 10°). The peak axial and radial strain of coal samples first increases rapidly and then stagnates. The peak volume strain rapid increases and then stagnates (θ = 0° and θ = 5°). When the inclination angle is 10°, the peak volume strain first decreases rapidly and then stagnates. Even if the upper limit of cyclic stress is lower than its UCS, it will still promote the propagation of micro cracks and the generation of new cracks and increase the internal damage of coal samples. With the increase of the cycle number, damage variables of coal samples after uniaxial cyclic compression and shear tests nonlinearly increase, and the growth rate decreases gradually.

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“…Overall, due to the important position of salt rock in underground energy storage (Qiu et al., 2018; Salmi et al., 2019), scholars have conducted so many researches on the creep properties of salt rock in recent years, and proposed various creep models (Lai et al., 2016; Nguyen et al., 2017; Zhou et al., 2018). However, when using these models to simulate the creep behavior of salt rock, almost all models need to artificially divide the continuous and complete creep process of salt rock into three stages (attenuation creep stage, steady creep stage, and accelerated creep stage), and use three different functions to describe the creep behavior of salt rock of different stages (Ganjiani, 2018; Hou et al., 2018). Therefore, the expressions of these models cannot be described with a unified function.…”

Section: Introductionmentioning

confidence: 99%

Creep properties and damage constitutive model of salt rock under uniaxial compression

Wang

Zhang

Song

et al. 2019

International Journal of Damage Mechanics

101

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To study the creep property of salt rock, uniaxial compression creep tests on salt rock specimens were carried out. The test results indicate that there is no steady creep of the salt rock used in this test in a strict sense. Even in the steady creep stage, the creep rate of salt rock changes continuously over time, but with a relatively smaller change range. When the axial stress does not exceed 9.5 MPa, the isochronous stress–strain curve of salt rock is approximately straight. While the axial stress exceeds 9.5 MPa, the isochronous stress–strain curve deflects to the strain axis, and the larger the axial stress, the more obvious the deflection. Thus, the long-term strength of the salt rock used in this test can be determined as 9.5 MPa. A mathematical expression for predicting the creep failure time of rock is proposed on the basis of assuming the change rule of rock strength over time conforms to the Usher function. Then starting from the variation in deformation modulus with respect to time in the creep process of salt rock, the elastic modulus of the damaged rock material is characterized by the deformation modulus, and the creep damage evolution equation of rock is established. Combined with the continuous damage mechanics theory, a new creep damage constitutive model for rock is proposed. The rationality of the model is verified using the uniaxial compression creep test results of salt rock. The results show that the new model can not only describe the attenuation and the steady creep of salt rock under low stress level, but also reflect the whole creep failure process under high stress level. The predicted curves under different axial stresses are all in good agreement with the test data.

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A Nonlinear Creep Damage Coupled Model for Rock Considering the Effect of Initial Damage

Cited by 123 publications

References 28 publications

An improved nonlinear damage model of rocks considering initial damage and damage evolution

An improved nonlinear damage model of rocks considering initial damage and damage evolution

Mechanical Properties and Damage in Lignite under Combined Cyclic Compression and Shear Loading

Creep properties and damage constitutive model of salt rock under uniaxial compression

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