Constitutive Model of Rock Uniaxial Damage Based on Rock Strength Statistics

Ji, Ming; Chen, Kai; Guo, Hong Jun

doi:10.1155/2018/5047834

Cited by 15 publications

(9 citation statements)

References 21 publications

(27 reference statements)

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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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“…As a special engineering rock mass, coal bodies typically have poor integrity, low strength, a high degree of fracture development, and random distribution of internal grains and fractures [1]. Coal and rock have been extensively studied within the fields of mechanics and energy [2][3][4][5][6][7][8]. Coal production conditions are affected by several factors including the natural environment, production, and technology, all of which can lead to complex mining conditions.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Fracture Strain Energy on the Burst Tendency of Coal Seams and Field Application

Guo

Liu

et al. 2021

Advances in Civil Engineering

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Coal is typically considered a special engineering rock mass because of its low strength, high internal fracture development, good permeability, and random distribution of microparticles and fractures. The results of cyclic loading and unloading tests indicate that the strain energy during the coal deformation process can be divided into three parts: plastic strain energy; fracture strain energy; and base-material strain energy. The energy composition ratio differs depending on coal strength. Lower proportions of fracture strain energy are associated with higher elastic energy indexes, and there is a negative correlation between fracture strain energy and other coal burst tendency indexes. The results were applied on the 4206 isolated island working face of coal mine A in Yan’an, Shanxi, China, yielding good benefits. The findings presented here provide a theoretical basis for understanding the principle of coal seam bursting and guidance for reducing burst risks.

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“…Based on this, mechanical properties of the rock material becomes more extremely complicate. Then, since Rummel and Fairhurst(1970) presented the rock stress-strain curves with a servo-controlled testing machine, many researchers (Huang and Yang, 2019;Krajcinovic et al, 1991;Yang and Jing, 2013;Yu et al, 2016;Cao et al, 2019;Ghasemi et al, 2017;Ji et al, 2018) began to pay more attention to the mechanical behaviors and constitutive relation in the rock failure process.…”

Section: Introductionmentioning

confidence: 99%

Constitutive model of rock triaxial damage based on the rock strength statistics

Chen

2020

International Journal of Damage Mechanics

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Firstly, an X-ray diffraction test is carried out to investigate brittle rock specimens’ composition, and a triaxial compression test is conducted to study the deformation behaviors and mechanical properties. Then, assuming that the rock material is able to be divided into the elastic part satisfying the Hooke’s law and the damage part where rock strength follows lognormal distribution, this paper determines a damage variable and establishes a damage constitutive model which effectively reflects the residual strength in the process of rock failure. Meanwhile, testing data are used to validate the reliability of the proposed model in this paper and the dependence of statistic parameters on the confining pressure. Finally, impacts caused by statistic parameters variation on compression strength are analyzed comprehensively, and we also conduct a comparison between this proposed model and other models from other literatures, thereby showing the reliability and rationality of this proposed model. In addition, the research outcomes presented in this paper also can effectively offer significant reference for the development of rock mechanics and rock engineering.

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Constitutive Model of Rock Uniaxial Damage Based on Rock Strength Statistics

Cited by 15 publications

References 21 publications

Elastic-Plastic Threshold and Rational Unloading Level of Rocks

Elastic-Plastic Threshold and Rational Unloading Level of Rocks

The Influence of Fracture Strain Energy on the Burst Tendency of Coal Seams and Field Application

Constitutive model of rock triaxial damage based on the rock strength statistics

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