A statistical damage constitutive model for rock based on modified Mohr–Coulomb strength criterion

In order to study the weakening mechanism of mechanical properties and the evolution of fracture of water-bearing rocks, cylindrical standard siltstone samples with four moisture contents (0, 2.85, 3.87, and 4.25%) were prepared, and the mechanical properties, damage mode, AE characteristics, and fractal law of water-bearing rock samples were studied by means of uniaxial compression test and acoustic emission (AE) monitoring technique, and based on the test findings, a constitutive model of the entire process of rock deformation and damage under uniaxial compression was built with different moisture content of rock. The results show that with the increase of moisture content, the peak stress, the stress threshold of void compaction stage, and the stress threshold of elastic stage of the rock samples decreased linearly, elastic modulus decreased exponentially as a function, and the peak strain, the strain threshold of void compaction stage, and the strain threshold of elastic stage increased linearly. The higher the moisture content, the weaker the AE signal intensity and the smaller the AE count value. From dry to saturated, the damage form of rock samples gradually transitioned from predominantly tensile damage to predominantly shear damage. The fractal dimension of the broken block linearly decreases as the moisture content rises. The model constructed in this paper has good applicability to the deformation characteristics of water-bearing rocks under uniaxial compression before the peak stress; it especially can express the rock void compaction stage, but it cannot accurately describe the postpeak deformation characteristics.

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“…Mohr-Coulomb criterion is used to express the strength of microelements [43], and the expression is as follows:…”

Section: Geofluidsmentioning

confidence: 99%

Mechanical Properties Damage, Fracture Evolution, and Constitutive Model of Siltstone under the Effect of Moisture Content

et al. 2022

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“…A damage-intrinsic model for the whole rock failure process has been developed using the triaxial test method, based on the Griffith strength criterion and assuming that the rock micro-element strength follows a Weibull distribution [4]. A triaxial compression test was carried out on quartz sand as the test specimen and a statistical damage-intrinsic model for the rock was proposed based on a modified Mohr-Coulomb strength criterion [5].…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and constitutive model of fractured red sandstone under acid corrosion

Liu

Wang³

2023

SN Appl. Sci.

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Red sandstone was selected for the study and specimens were prepared at 0°, 30°, 45° and 60° fracture inclinations and maintained in an acid solution at pH = 2. The specimens were subjected to uniaxial compression tests before and after maintenance to obtain the mechanical parameters and to observe the damage properties of the specimens. Based on the Lemaitre strain equivalence principle, a macroscopic fracture model for single-fissure rock masses and a statistical damage model for the Weibull distribution of micro-fissures were combined to derive macro-and micro-coupled damage variables for the specimens. The damage variables after acid solution corrosion are considered to derive the constitutive model for fractured red sandstone containing fractures after acid corrosion. The theoretical damage constitutive curves were compared with the experimental curves to analyse the applicability of the constitutive equation. The results show that the peak stress, peak strain and elastic modulus of the fractured specimens all vary regularly with the inclination angle, first decreasing and then increasing with the increase in the inclination angle; the peak compressive strength and elastic modulus of the fractured sandstone all tend to decrease and the peak strain tends to increase after corrosion by acid solution; the damage characteristics of the fractured sandstone are more influenced by the inclination angle and less influenced by acid corrosion; by comparing the theoretical curve with the experimental curve, the established damage constitutive model is in good agreement at the elastic deformation and plastic yielding stages. The mechanical properties of rock masses with different inclinations of fracture are quantified on the basis of the test results. The damage characteristics of rock masses with different fracture inclinations under normal and acid corrosion conditions are studied. The macro- and micro-coupled damage variables of fractured rock masses under acid corrosion are derived and validated.

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“…Pan Jiliang et al [ 15 ] proposed a damage ontological model combining hydrochemical damage with coupled damage of microcracks and macroscopic single fissures. Peng Zhixiong et al [ 16 ] proposed a new model for the statistical damage constitution of rocks in deep strata under the assumptions that the neutron strength of rocks follows a two-parameter Weibull distribution and the neutron damage follows a modified Mohr–Coulomb strength criterion. Mansour Sabri et al [ 17 ] experimentally investigated the effect of grain size on the damage mechanism and fracture toughness of rock specimens.…”

Section: Introductionmentioning

confidence: 99%

Constitutive Model and Fracture Failure of Sandstone Damage under High Temperature–Cyclic Stress

Luo

2022

Materials

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Deformation and damage characteristics of high-temperature rocks during underground coal gasification are the fundamental mechanical problems encountered in coal-bed gasification production. In order to study the characteristics of deformation and damage processes of rocks under the joint action of high temperature and high stress, a damage intrinsic model under the joint action of high temperature–cyclic loading is needed. In this paper, we used the damage mechanics theory to establish the damage instantiation model of rocks under the joint action of high temperature loads based on the Mohr–Coulomb strength criterion. It was found that the higher the temperature, the lower the strength of sandstone, the lower the peak stress, and the higher the peak strain, the peak stress decreased from 95.6 MPa at room temperature to 74.8 MPa at 400 °C to 49.5 MPa at 800 °C, and the peak strain increased from room temperature to 400 °C to 800 °C by 27.9% and 33.4%, respectively. With the increase in temperature, the internal microcracks of sandstone increased and expanded, which caused the degree of damage to intensify, and the macroscopic expression was the reduction in strength and stiffness of the sandstone. The rock went through four stages from loading to damage, including damage weakening, plastic deformation, strain softening, and residual deformation. The four types of fractures that led to the overall rupture of the rock were open fracture, secondary coplanar fracture, secondary inclined fracture, and oblique fracture. The damage intrinsic model constructed in this paper could better reflect the damage process of thermally damaged sandstone under the action of periodic loading, and had certain rationality. The damage intrinsic evolution curve, as well as the damage mechanism of sandstone under the action of macroscopic high temperature-loading, were discussed from the perspective of microscopic damage evolution, and the fracture extension pattern and penetration mechanism of the rock under different temperatures were analyzed. The research results provide an important reference for the design and engineering application of gasifiers in coal-bed underground gasification projects.

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A statistical damage constitutive model for rock based on modified Mohr–Coulomb strength criterion

Cited by 7 publications

References 44 publications

Mechanical Properties Damage, Fracture Evolution, and Constitutive Model of Siltstone under the Effect of Moisture Content

Mechanical Properties Damage, Fracture Evolution, and Constitutive Model of Siltstone under the Effect of Moisture Content

Mechanical properties and constitutive model of fractured red sandstone under acid corrosion

Constitutive Model and Fracture Failure of Sandstone Damage under High Temperature–Cyclic Stress

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