Analysis of Strength and permeability of crystalline sandstone under loading-unloading conditions

Yang, Yushun; Zhang, Dongming; Zhang, Bang-an; Ye, Chen; Yang, Bo

doi:10.1080/15567036.2019.1568637

Cited by 9 publications

(3 citation statements)

References 15 publications

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“…10 Additionally, the obtained solid products have a relatively small specic surface area, which limits their application potential. Consequently, researchers have employed various strategies to improve the quality of the pyrolysis products, such as altering the pyrolysis temperature, 11,12 and atmosphere, 13 incorporating catalysts, and implementing biomass pretreatment. 14 Among these strategies, adding a catalyst offers signicant advantages.…”

Section: Introductionmentioning

confidence: 99%

Catalytic pyrolysis and in situ carbonization of walnut shells: poly-generation and enhanced electrochemical performance of carbons

He,

Liu,

Zhang

et al. 2024

RSC Adv.

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Section: Introductionmentioning

confidence: 99%

Catalytic pyrolysis and in situ carbonization of walnut shells: poly-generation and enhanced electrochemical performance of carbons

He,

Liu,

Zhang

et al. 2024

RSC Adv.

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“…Therefore, the seepage characteristics of fluids in porous and fractured rock masses under hydro-mechanical coupling are of great significance to the engineering safety of underground rock masses. Many scholars have conducted extensive studies on the flow behaviors of fluids in pores and fractures based on Darcy's law [1][2][3][4][5][6][7][8]. However, linear Darcy's law is not sufficient to describe the seepage behaviors in pores and fractures with an increased flow rate, which exhibit significant nonlinear seepage characteristics.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Seepage Behaviors of Pore-Fracture Sandstone under Hydro-Mechanical Coupling

Zhang

Guo

et al. 2022

Crystals

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This work focused on the nonlinear seepage behaviors of flow in pore-fracture media. Natural sandstones were selected to prefabricate single-fracture specimens with different inclinations (0–90°). Seepage tests of combined media were performed under different confining pressures (8–10 MPa) and different water pressures (3–7 MPa) in a triaxial pressure chamber. The fitting analysis of experimental data showed that Forchheimer’s law described the nonlinear characteristics of flow in the pore-fracture media. Linear term coefficient a and nonlinear term coefficient b of the sandstone samples with different inclinations changed more obviously with the increased inclination. When the fracture inclination was greater than 30°, a and b values had a sudden jump. The nonlinear inertial-parameter equation of fluid flow in pore-fracture media was proposed based on non-Darcy flow coefficient β and inherent permeability k. The applicability of the following methods to evaluate Darcy’s law was discussed, including normalized hydraulic conductivity, pressure gradient ratio, and discharge ratio. The three methods were able to determine critical parameters and distinguish linear and nonlinear flow. Furthermore, it was specified for the first time that when β was negative, critical nonlinear effect E was −0.1, and Forchheimer’s coefficient F0 was −0.091. In the −∇P-Q relationship, the fitting curve was convex to the −∇P axis, and the increase of Q was higher than the linear increase, presenting the nonlinearity of overflow. On the one hand, the fractures and pores were compressed under the confining pressure due to the prefabricated fractures of different shapes and different inclinations. A higher seepage water pressure was needed to stabilize the seepage system with the excessive flow rate. On the other hand, the barrier effect of the fluid inside the rock was completely lost because the fluid expanded the seepage channel. Its permeability was changed, leading to seepage instability.

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“…In addition, triaxial unloading experiments under different initial damages, unloading rates and stress levels were carried out, and the influence of various factors on the rock were analyzed 8 – 10 . Various rock strength and failure criteria can reflect the strength characteristics of unloading rocks based on unloading tests, among which are the Mohr–Coulomb criterion 11 , Hoek–Brown criterion 12 and Mogi–Coulomb criterion 13 that are often used. Wu et al 14 showed that the Mohr Coulomb failure criterion cannot accurately describe the strength characteristics of rock in unloaded state.…”

Section: Introductionmentioning

confidence: 99%

Study on mechanical properties and fracture surface characteristics of argillaceous sandstone under different stress paths

Huang

Wang

et al. 2022

Sci Rep

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To study the differences in mechanical properties and failure characteristics of underground chambers surrounding rock under different stress conditions, triaxial loading and unloading tests were carried out on argillaceous sandstone. The three-dimensional topography parameters of the fracture surface were obtained by using high-precision three-dimensional topography scanning technology, including six height characteristic parameters and two texture parameters. Compared with the triaxial loading test, the strength, peak strain and residual strength of argillaceous sandstone with the same confining pressure under unloading conditions all decrease, and the stress–strain curve changes from ductility to brittleness. The Mogi–Coulomb strength criterion can better describe the strength properties of argillaceous sandstones than the Mohr–Coulomb and Drucker–Prager strength criteria. Under the unloading condition, the cohesion c decreased by 30.87% and the internal friction angle φ increased by 30.87% compared with the loading condition. The tensile cracks perpendicular to the unloading direction is formed during unloading, resulting in large roughness, dispersion and fluctuation of fracture surface.

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Analysis of Strength and permeability of crystalline sandstone under loading-unloading conditions

Cited by 9 publications

References 15 publications

Catalytic pyrolysis and in situ carbonization of walnut shells: poly-generation and enhanced electrochemical performance of carbons

Catalytic pyrolysis and in situ carbonization of walnut shells: poly-generation and enhanced electrochemical performance of carbons

Nonlinear Seepage Behaviors of Pore-Fracture Sandstone under Hydro-Mechanical Coupling

Study on mechanical properties and fracture surface characteristics of argillaceous sandstone under different stress paths

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