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Effect of initial suction on the stiffness and strength of densely compacted Gaomiaozi bentonite
https://orcid.org/0000-0002-6571-2549
Abstract Knowledge of the mechanical properties of compacted bentonite is essential to assessing the performance of an engineered barrier system in a high-level radioactive waste repository. In this study, direct shear tests and uniaxial compression tests were conducted on compacted Gaomiaozi bentonite with a dry density of 1.7 g/cm3 to investigate its stiffness and strength characteristics at various initial suction levels. Specimens were found to exhibit brittle failure within an initial suction range of 11–223 MPa. The peak shear strength and shear modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 126 MPa. The residual shear strength was found to increase with increasing initial suction within 11–223 MPa. The uniaxial compressive strength and elastic modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 62 MPa. Models were developed to predict the stiffness and strength of the specimens as a function of the initial suction and effective stress parameter (χ). For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, using the degree of saturation (S r) and effective degree of saturation (S e) in place of χ produced the same trends which diverged from the test results at initial suction levels lower than 12 MPa and higher than 126 MPa. However, using S r and S e in place of χ reasonably reproduced the residual shear strength within an initial suction range of 11–223 MPa. In contrast, using (S r)α (S r raised to an exponent α) in place of χ reproduced the test results well. For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, the simulations required a value of 2.4 for the α. For the residual shear strength, the best value of α was 1.0. Based on the testing method and model approach developed in this study, the evolution of the stiffness and strength of compacted bentonite along wetting and drying paths can be further explored.
Highlights Stiffness and strength were determined via direct shear and uniaxial compression tests. Stiffness and strength were modeled using the effective stress parameter χ. Peak strength and stiffness modeling requires α = 2.4 when using (S r)α as the χ. Residual shear strength modeling requires α = 1.0 when using (S r)α as the χ.
Effect of initial suction on the stiffness and strength of densely compacted Gaomiaozi bentonite
https://orcid.org/0000-0002-6571-2549
Abstract Knowledge of the mechanical properties of compacted bentonite is essential to assessing the performance of an engineered barrier system in a high-level radioactive waste repository. In this study, direct shear tests and uniaxial compression tests were conducted on compacted Gaomiaozi bentonite with a dry density of 1.7 g/cm3 to investigate its stiffness and strength characteristics at various initial suction levels. Specimens were found to exhibit brittle failure within an initial suction range of 11–223 MPa. The peak shear strength and shear modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 126 MPa. The residual shear strength was found to increase with increasing initial suction within 11–223 MPa. The uniaxial compressive strength and elastic modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 62 MPa. Models were developed to predict the stiffness and strength of the specimens as a function of the initial suction and effective stress parameter (χ). For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, using the degree of saturation (S r) and effective degree of saturation (S e) in place of χ produced the same trends which diverged from the test results at initial suction levels lower than 12 MPa and higher than 126 MPa. However, using S r and S e in place of χ reasonably reproduced the residual shear strength within an initial suction range of 11–223 MPa. In contrast, using (S r)α (S r raised to an exponent α) in place of χ reproduced the test results well. For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, the simulations required a value of 2.4 for the α. For the residual shear strength, the best value of α was 1.0. Based on the testing method and model approach developed in this study, the evolution of the stiffness and strength of compacted bentonite along wetting and drying paths can be further explored.
Highlights Stiffness and strength were determined via direct shear and uniaxial compression tests. Stiffness and strength were modeled using the effective stress parameter χ. Peak strength and stiffness modeling requires α = 2.4 when using (S r)α as the χ. Residual shear strength modeling requires α = 1.0 when using (S r)α as the χ.
Effect of initial suction on the stiffness and strength of densely compacted Gaomiaozi bentonite
https://orcid.org/0000-0002-6571-2549
Abstract Knowledge of the mechanical properties of compacted bentonite is essential to assessing the performance of an engineered barrier system in a high-level radioactive waste repository. In this study, direct shear tests and uniaxial compression tests were conducted on compacted Gaomiaozi bentonite with a dry density of 1.7 g/cm3 to investigate its stiffness and strength characteristics at various initial suction levels. Specimens were found to exhibit brittle failure within an initial suction range of 11–223 MPa. The peak shear strength and shear modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 126 MPa. The residual shear strength was found to increase with increasing initial suction within 11–223 MPa. The uniaxial compressive strength and elastic modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 62 MPa. Models were developed to predict the stiffness and strength of the specimens as a function of the initial suction and effective stress parameter (χ). For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, using the degree of saturation (S r) and effective degree of saturation (S e) in place of χ produced the same trends which diverged from the test results at initial suction levels lower than 12 MPa and higher than 126 MPa. However, using S r and S e in place of χ reasonably reproduced the residual shear strength within an initial suction range of 11–223 MPa. In contrast, using (S r)α (S r raised to an exponent α) in place of χ reproduced the test results well. For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, the simulations required a value of 2.4 for the α. For the residual shear strength, the best value of α was 1.0. Based on the testing method and model approach developed in this study, the evolution of the stiffness and strength of compacted bentonite along wetting and drying paths can be further explored.
Highlights Stiffness and strength were determined via direct shear and uniaxial compression tests. Stiffness and strength were modeled using the effective stress parameter χ. Peak strength and stiffness modeling requires α = 2.4 when using (S r)α as the χ. Residual shear strength modeling requires α = 1.0 when using (S r)α as the χ.
Effect of initial suction on the stiffness and strength of densely compacted Gaomiaozi bentonite
Dong, Xin-Xin (author) / Chen, Yong-Gui (author) / Ye, Wei-Min (author) / Cui, Yu-Jun (author)
Applied Clay Science ; 194
2020-05-22
Article (Journal)
Electronic Resource
English