Mechanical behaviors of cemented sand and gravel materials based on triaxial tests during unloading and reloading

CAI Xin; JIANG Min-min; SHAN Yan-gong; YANG Jie; YANG An-yu; GUO Xing-wen

doi:10.11779/CJGE2020S2034

Volume 42 Issue S2

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Chinese Journal of Geotechnical Engineering > 2020 > 42(S2): 190-195. > DOI: 10.11779/CJGE2020S2034

CAI Xin, JIANG Min-min, SHAN Yan-gong, YANG Jie, YANG An-yu, GUO Xing-wen. Mechanical behaviors of cemented sand and gravel materials based on triaxial tests during unloading and reloading[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(S2): 190-195. DOI: 10.11779/CJGE2020S2034

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Mechanical behaviors of cemented sand and gravel materials based on triaxial tests during unloading and reloading

CAI Xin^{1, 3, 6,},
JIANG Min-min^{1, 3},
SHAN Yan-gong⁴,
YANG Jie^{1, 2, ,},
YANG An-yu⁵,
GUO Xing-wen⁶

1.
State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China
2.
School of Transportation and Civil Engineering, Nantong University, Nantong 226019, China
3.
College of Mechanics and Materials, Hohai University, Nanjing 210098, China
4.
Nanjing Branch of Jiangsu Province Hydrology and Water Resources Investigation Bureau, Nanjing 210008, China
5.
National Research Institute for Rural Electrification, Hanzhou 310012, China
6.
College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China

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Received Date: August 31, 2020
Available Online: December 07, 2022

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Abstract

Abstract

Understanding the mechanical behaviors of cemented sand and gravel materials during unloading and reloading in the context of the unloading and reloading paths can help enhance the accuracy of predicting the stress and deformation of cemented sand and gravel dams during reservoir storage and discharge. To this end, a large shear triaxial instrument is used to conduct the triaxial unloading and reloading tests on the cemented sand and gravel materials under different confining pressures and stress levels with a cemented content of 100 kg/m³. The triaxial shear test results obtained under loading are systematically analyzed along with the stress and deformation of the materials obtained in the triaxial tests pertaining to the unloading and reloading paths. The results indicate that the increase in the internal friction angle and cohesive force enhances the peak strength of the cemented sand and gravel materials in the unloading and reloading paths. The stress levels do not considerably affect the unloading modulus of the materials. However, with the increase in the confining pressure, the resilient modulus first increases nonlinearly and later decreases gradually. Under different confining pressures, the ratio of the average of the resilient modulus to the initial modulus remains constant. The variation trend of the volume of the cemented sand and gravel materials at the loading stage of the triaxial unloading and reloading tests is the same as that during the loading tests, that is, it first increases and later decreases. With the increase in the same confining pressure under the stress level, the unloading carrier shrinkage of the specimen gradually changes to unloading carrier expansion. These findings may provide valuable experimental bases to construct a realistic constitutive model for cemented sand and gravel materials.
- cemented sand and gravel material,
- triaxial test,
- resilient modulus,
- unloading volume contraction

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References

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