Modeling of inherent anisotropic behavior of partially saturated clayey rocks

Hu, Dawei; Zhou, Hui; Zhang, Fan; Shao, Jian‐Fu; Zhang, Junfeng

doi:10.1016/j.compgeo.2012.09.002

Cited by 21 publications

(4 citation statements)

References 39 publications

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“…[34][35][36][37][38] In some clay-rich shales, these processes have been observed to induce changes in the degree of mechanical anisotropy. 39,40 Mechanical anisotropy has been shown to be saturation-dependent in these rocks, with the anisotropy ratio generally increasing as the shale dehydrates. 38,[41][42][43] The Young's modulus and compressive strength were found to be more sensitive to the degree of saturation (DOS) in the BP direction.…”

Section: Introductionmentioning

confidence: 99%

“…The behavior of clay rocks subjected to desiccation and hydration processes has been studied in the literature 34–38 . In some clay‐rich shales, these processes have been observed to induce changes in the degree of mechanical anisotropy 39,40 . Mechanical anisotropy has been shown to be saturation‐dependent in these rocks, with the anisotropy ratio generally increasing as the shale dehydrates 38,41–43 .…”

Section: Introductionmentioning

confidence: 99%

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Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

Borja

2021

Num Anal Meth Geomechanics

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Many clay rocks have distinct bedding planes. Experimental studies have shown that their mechanical properties evolve with the degree of saturation (DOS), often with higher stiffness and strength after drying. For transversely isotropic rocks, the effects of saturation can differ between the bed-normal (BN) and bedparallel (BP) directions, which gives rise to saturation-dependent stiffness and strength anisotropy. Accurate prediction of the mechanical behavior of clay rocks under partially saturated conditions requires numerical models that can capture the evolving elastic and plastic anisotropy with DOS. In this study, we present an anisotropy framework for coupled solid deformation-fluid flow in unsaturated elastoplastic media. We incorporate saturation-dependent strength anisotropy into an anisotropic modified Cam-Clay (MCC) model and consider the evolving anisotropy in both the elastic and plastic responses. The model was calibrated using experimental data from triaxial tests to demonstrate its capability in capturing strength anisotropy at various levels of saturation. Through numerical simulations, we demonstrate the role of evolving stiffness and strength anisotropy in the mechanical behavior of clay rocks. Plane strain simulations of triaxial compression tests were also conducted to demonstrate the impacts of material anisotropy and DOS on the mechanical and fluid flow responses.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

Borja

2021

Num Anal Meth Geomechanics

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“…The number could not be generated for other material since some other material showing a lower number such as gneiss is showing a fracture angle about 45 o . The number of fracture angle depends on the deformability of rock, modulus, strength, permeability, and orientation of plane [13], [14]. Modified failure criterion shall be conducted on the isotropic rock for different plane bedding shares.…”

Section: Introductionmentioning

confidence: 99%

New Constants of Fracture Angle on Quartz Sandstone

Supandi

Zakaria

Sukiyah

et al. 2020

Int. J. Adv. Sci. Eng. Inf. Technol.

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Calculation of fracture angle based on the Mohr-Coulomb concept has been generalized to all lithologies, whereas each lithology has a heterogeneous characteristic that is not the same as one another. This research aims to determine constants that calculating the fracture angle based on the Mohr-Coulomb concept for quartz sandstone. The fracture angle based on the results of calculations using mathematical formulas and measurement results in the laboratory is compared. The empirical result for analysis was obtained from direct measurement under the uniaxial test with a single fracture and compared them based on mathematical calculation. Laboratory testing was applied to 50 mm-sized core samples of sandstone. The value of the fracture angle was obtained after taking uniaxial testing with fracture angle measurement against the plane directly. The determination of the friction angle was performed using an undrained-unconsolidated triaxial method. The determination of the correlation constants was conducted by plotting the scatter graph between the friction angle and fracture angle. The correlation shows that the fracture angle has a very strong relationship with rock characteristics. The constants based on the laboratory test are higher than that of the Mohr-Coulomb concept. The increasing constants depend on several factors: mineralogy, cohesion, internal friction angle, density, void ratio, and Poisson's ratio. The constants of the fracture angle for the quartz sandstone should be changed from 45 to 53.705. This result may be proof that generalizing the formula of fracture angle to all lithologies may not be applied due to the differences of their characteristics in defining the fracture angle.

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“…Within the framework of poroplasticity and continuum damage mechanics, some elastoplastic damage coupled models have been proposed. Main features, such as the elastic degradation due to microcracks, coupling between plastic deformation and induced damage, the influence of water saturation on plastic flow and damage evolution, as well as the variation of permeability with induced damage, are taken into account (Belhouari et al., 2014; Bui et al., 2016; Ciantia and Prisco, 2016; Hu et al., 2013; Jia et al., 2010; Jia et al., 2010; Ma et al., 2016; Pereira and Arson, 2013; Shao et al., 2006; Zhang et al., 2013). However, these studies mostly concern single influencing factor and the elastoplastic damage property of rock mass under the coupling effect of water and petrol environment is rarely concerned.…”

Section: Introductionmentioning

confidence: 99%

An elastic–plastic damage model considering capillary effect for petrol–water saturated sandstone

Yang

Luo

et al. 2017

International Journal of Damage Mechanics

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The mechanical behavior of surrounding rock mass is key important to the water-sealed petrol storage caverns because of the two phase environment. To investigate the strength and damage mechanism of rock mass under petrol–water immersion circumstance, an elastic–plastic damage constitutive model is proposed. The deformation work of rock mass is derived according to the mixture theory and averaging methods. In order to further study the capillary action influence of petrol–water liquid phase on the strength and stiffness of rock mass, the plastic yield condition considering petrol–water circumstance is proposed. Then, the stress–strain increment expression under the influence of both liquid and solid phase is deduced through the consistency condition. Meanwhile, the damage conditions of the rock mass under tensile and compressive stress differ a lot, so the rock mass damage model under petrol–water circumstance is established combining the tensile and compressive damage criterion and the damage evolution law. The proposed constitutive model is adopted to simulate the mechanical property and damage evolution feature of rock mass under axial compression. The results suggest that the increase in the petrol pressure leads to the improvement of the axial strength for rock mass and meanwhile, the occurrence of damage is also advanced. In addition, the elastic–plastic property of the rock material has been well developed below the stress peak point during this process. Ultimately, the proposed elastic–plastic damage constitutive model was verified by making comparisons between the theoretical calculating results and experimental results.

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Modeling of inherent anisotropic behavior of partially saturated clayey rocks

Cited by 21 publications

References 39 publications

Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

New Constants of Fracture Angle on Quartz Sandstone

An elastic–plastic damage model considering capillary effect for petrol–water saturated sandstone

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