Estimation of creep parameters of rock salt from uniaxial compression tests

Singh, Aditya; Kumar, Chandan; Kannan, L. Gopi; Rao, K. Seshagiri; Ayothiraman, Ramanathan

doi:10.1016/j.ijrmms.2018.04.037

Cited by 106 publications

(34 citation statements)

References 15 publications

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“…Rock mechanics studies have been extensively conducted in China and abroad, which cover a broad range, from uniaxial to triaxial compression, simple to multiple conditions, and single to complex paths [1][2][3][4][5][6]. In triaxial tests, the initial stress level mainly includes the initial confining pressure and the initial axial pressure.…”

Section: Introductionmentioning

confidence: 99%

Elastic-Plastic Threshold and Rational Unloading Level of Rocks

Guo

2019

Applied Sciences

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During loading and unloading test, various rocks manifest different stress values of elastic-plastic transformation. This study proposes to include axial pressure increment ratio in the conventional triaxial compression test to evaluate different variables (nominal elastic modulus, nominal Poisson's ratio, strain, and energy). The relationships among various factors including variables, the stress level of initial confining stress and axial pressures, were analyzed by analyzing the stress-strain plot record obtained from testing various rocks. The extreme value point of the deformation parameter, also known as the elastic-plastic threshold, was analyzed. In addition, the elastic-plastic thresholds were later used as unloading points during the unloading tests. Under the same confining condition, different rocks demonstrated different unloading levels. Furthermore, a linear correlation was observed between unloading levels and changing confining pressures, and the gradient is mainly related to the types of rocks. During the unloading tests of rocks, the rational unloading level is recommended to be no higher than the stress level at the elastic-plastic threshold under the corresponding confining pressure. Appl. Sci. 2019, 9, 3164 2 of 15 and the unloading level has no significant effect on the energy evolution process. Zhang [11] and Zhu [12] considered that the unloading stress level mitigated possible damage within rocks during the unloading damage stage. Regarding the initial axial pressure of unloading, Liu et al. [13] selected 50% of the conventional triaxial compressive strength and the corresponding confining pressure, whereas other researchers often adopted 60% and 80% [14][15][16], 70% [17][18][19][20], 80-90% [21], and 15-90% [22]. Most researchers selected 80% of the peak strength as the loaded axial pressure in unloading tests [23][24][25][26]. Details of studies discussed above can be viewed in Table 1. However, mentioned studies failed to consider the effects of the initial axial pressure during exploring the effects of unloading on rock failures.

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Section: Introductionmentioning

confidence: 99%

Elastic-Plastic Threshold and Rational Unloading Level of Rocks

Guo

2019

Applied Sciences

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“…The 1D state: the total strain 휀 of the fractional model according to the rheological model theory would satisfy the following conditions [14,15]:…”

Section: Establishment Of Deteriorated Abel Dashpot Creep Modelmentioning

confidence: 99%

The 3D Nonstationary Creep Constitutive Model of Sandstone Based on Fractional Order

Zhang

Liu

2019

Mathematical Problems in Engineering

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Based on nonlinear creep characteristics of rock, triaxial creep tests were conducted on sandstone by using an MTS812.02 test machine. The creep properties of rocks under different conditions were analyzed. Establishing a creep model that describes parameter degradation is necessary to address the deterioration of rock creep parameters over time. A nonstationary Abel pot was constructed on the basis of laws of damage accumulation and deterioration. Then, the nonstationary creep model was established according to fractional order theory. The parameters of the triaxial creep test curve under different confining pressures were identified on the basis of Levenberg–Marquardt algorithm in Hengda coal mine in Fuxin, China. By comparing the model curve with the experimental curve, we found that the nonlinear model not only accurately reflected the creep characteristics of the decay and steady creep stages but also overcame the limitation of traditional creep model, that is, difficulty in describing the accelerated creep. Finally, the influence of fractional order and nonstationary parameters on rock creep was obtained by parameter sensitivity analysis. Overall, the model had high fitting degree as well as good prediction and analysis for 3D creep test data.

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“…Numerous studies have shown that rocks exhibit typical nonlinear characteristics during creep, in which the accelerated creep stage is the most obvious [4,11,12]. To reveal the mechanical properties of rock rheological behavior, scholars have conducted targeted in-depth research and obtained abundant research results [13][14][15]. By summarizing existing rheological models, Xia et al [16] proposed a unified rheological mechanical model.…”

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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Estimation of creep parameters of rock salt from uniaxial compression tests

Cited by 106 publications

References 15 publications

Elastic-Plastic Threshold and Rational Unloading Level of Rocks

Elastic-Plastic Threshold and Rational Unloading Level of Rocks

The 3D Nonstationary Creep Constitutive Model of Sandstone Based on Fractional Order

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

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