Effects of prior cyclic loading damage on failure characteristics of sandstone under true-triaxial unloading conditions

Fan, Xiangqian; Jiang, Deyi; Wu, Fei; Zou, Quanle; Chen, Jie; Chen, Bin; Sun, Zhongguang

doi:10.1016/j.ijrmms.2020.104379

Cited by 62 publications

(20 citation statements)

References 46 publications

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“…It is worthy emphasizing that to shorten the computational time for practical consideration, a total of 5606 particles whose radii ranged from 1.8 to 2.1 mm and followed a uniform distribution were generated in the numerical model. The particle was about 20 times larger than the real mineral grain, 6 but its size could meet the standard of American Society for Testing and Materials (ASTM) that suggests the ratio of the smallest specimen model length to the average grain diameter be more than 10, which had little effect on the simulation results. 47 The particles were bonded by parallel-bond contacts, as shown in Figure 4.…”

Section: Model Generation and Microparameter Calibrationmentioning

confidence: 94%

“…[2][3][4] To gain deep insight into the unloading behavior of a rock mass during underground excavation, many experimental investigations have been carried out on rocks in the laboratory. [5][6][7][8] Ding et al 9 carried out conventional triaxial compression and unloading confining pressure tests to investigate the failure behaviors of sandstone after different high-temperature treatments. The results showed that brittle failure was more obvious in the unloading confining pressure tests with the increase in initial confining pressure.…”

Section: Introductionmentioning

confidence: 99%

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Deformation and failure characteristics of sandstone subjected to true‐triaxial unloading: An experimental and numerical study

Fan

Jiang

et al. 2021

Fatigue Fract Eng Mat Struct

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In this research, we conducted both laboratory experiments and discrete element simulations to investigate the influence of maximum principal stress level on true‐triaxial unloading behaviors of sandstone samples. The results show that as the level of σ1 at the unloading point increases, the ultimate bearing capacity of sandstone sample is increasingly strengthened, while the sample collapses more easily during the unloading process, and the failure mode of sample changes from mixed tensile‐shear failure to shear failure. With the increase in the level of σ1, the accumulative micro‐cracks at the unloading point and micro‐crack generation rate during the unloading phase exhibit increasing trends, while the ratio between the number of tensile micro‐cracks and shear micro‐cracks generally shows a downward trend. The formation of macro fracture in sandstone sample is closely related to the material inhomogeneity and true‐triaxial stress state.

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Section: Model Generation and Microparameter Calibrationmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Deformation and failure characteristics of sandstone subjected to true‐triaxial unloading: An experimental and numerical study

Fan

Jiang

et al. 2021

Fatigue Fract Eng Mat Struct

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“…where σ i 3 is the real-time stress value in the σ 3 direction during unloading σ 3 and H reflects the overall unloading degree of σ 3 . e initial confining pressure and the magnitude of the unloaded stress in the unloading direction have an obvious impact on the rock deformation, failure, and strength parameters' degradation during the unloading process [34]. Quantitative research on the change law of mechanical parameters during rock unloading by H has strong theoretical and practical significance [35].…”

Section: Deformation Modulus and Unloading Ratiomentioning

confidence: 99%

Unloading Mechanics and Energy Characteristics of Sandstone under Different Intermediate Principal Stress Conditions

Zhang

et al. 2021

Advances in Civil Engineering

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The TRW-3000 true triaxial rock testing machine was used to conduct loading and unloading tests of sandstone under different σ 2 , and the true triaxial lateral unloading mechanics and energy characteristics of sandstone under different σ 2 were studied. The experimental results show the following: (1) compared with the results of the loading test, the peak strength of the sandstone under the unloading σ 3 path is reduced, the unloading direction has obvious expansion and deformation, and the amount of expansion increases significantly with the increase of σ 2 ; sudden brittle failure occurs at the end of unloading. E gradually decreases with the increase of H, and it performs well to use the cubic polynomial to fit the curve of E-H. (2) The Mogi–Coulomb strength criterion can accurately describe the true triaxial strength characteristics of sandstone under loading and unloading conditions. Compared with the results of the loading test, the values of c and φ obtained based on this criterion under the unloading σ 3 path are reduced. (3) Under the condition of unloading σ 3 , U, U e , and U d , when the specimen is broken, are all linearly positively correlated with σ 2 . U d increases nonlinearly with the increase of H, and as σ 2 increases, the slope of the U d -H curve becomes larger, and the specimen consumes more energy under the same unloading amount. Most of the energy absorbed by the specimen under the unloading σ 3 path is converted into U e , but as σ 2 increases, U d / U increases, and the energy consumed when the specimen is broken is greater.

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“…[9][10][11][12][13][14][15] Wen et al 16 studied the energy evolution law of intact red sandstone under different loading conditions and explained its different failure mechanisms according to the various laws of energy evolution of sandstone under action of different stress scenarios. Xiao et al 17 examined the influence of the first cyclic loading damage on the subsequent breaking and unloading failure characteristics from the energy conversion point of view. It was shown that the number of cyclic loading has a substantial impact on the energy storage capacity of the rock.…”

Section: Introductionmentioning

confidence: 99%

Energy characteristics of sandstones with different crack angles under true triaxial cyclic loading and unloading

Xia

Luo

et al. 2022

Energy Science & Engineering

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The effect of crack angle on energy evolution during sandstone failure subjected to true triaxial cyclic loading and unloading is of great concern. However, the energy consumed in the crack initiation and compaction process is generally referred to the dissipated energy, which is inaccurate. To reveal the energy law in the breaking process of sandstone, a complex cyclic loading and unloading test is carried out on precast angled sandstone samples by employing the triaxial test system. The area integral methodology is exploited to evaluate the evolution of total energy density, elastic energy density, dissipated energy density, and plastic energy density of the rock samples of different crack angles. The variations of these four energy density levels in terms of the number of loading and unloading cycles and the upper limit of stress are explained and discussed. The obtained results reveal that during the entire cycle of loading and unloading, the variations of the above‐mentioned factors of the rock sample fairly do not rely on the crack angle. The energy density increases with the number of cycles, and the total energy density and elastic energy density significantly increase faster than the consumption mode. The growth rate of the dissipative energy density is greater than that of the plastic energy density. Additionally, the aforementioned four energy quantities grow in a quadratic manner as a function of the upper limit of the loading stress. The releasable elastic energy gradually magnifies by increasing the upper limit of the loading stress. The plasticity density first decreases and then increases, reflecting the change law of the irreversible plastic deformation caused by newly developed cracks in the rock sample. The elastic energy density, the fitting coefficient of the dissipated energy density, and the total energy density are employed to define the characteristic coefficients of the rock energy storage and energy dissipation. The results indicate that the larger the rock crack angle, the stronger the energy storage energy and the weaker the energy dissipation capacity. It also explains that how the strength of the rock sample becomes higher as the crack angle increases.

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Effects of prior cyclic loading damage on failure characteristics of sandstone under true-triaxial unloading conditions

Cited by 62 publications

References 46 publications

Deformation and failure characteristics of sandstone subjected to true‐triaxial unloading: An experimental and numerical study

Deformation and failure characteristics of sandstone subjected to true‐triaxial unloading: An experimental and numerical study

Unloading Mechanics and Energy Characteristics of Sandstone under Different Intermediate Principal Stress Conditions

Energy characteristics of sandstones with different crack angles under true triaxial cyclic loading and unloading

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