Experimental study on mechanical behavior of sand and silty clay under vertical unloading

WU Kai; CHEN Renpeng; MENG Fanyan; HU Bo

doi:10.11779/CJGE20230850

Volume 46 Issue 10

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Chinese Journal of Geotechnical Engineering > 2024 > 46(10): 2174-2182. > DOI: 10.11779/CJGE20230850

WU Kai, CHEN Renpeng, MENG Fanyan, HU Bo. Experimental study on mechanical behavior of sand and silty clay under vertical unloading[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(10): 2174-2182. DOI: 10.11779/CJGE20230850

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Experimental study on mechanical behavior of sand and silty clay under vertical unloading

WU Kai^{1, 2, 3,},
CHEN Renpeng^{1, 2, 3, ,},
MENG Fanyan^{1, 2, 3},
HU Bo²

1.
Research Center for Advanced Underground Space Technologies of Hunan University, Changsha 410082, China
2.
College of Civil Engineering, Hunan University, Changsha 410082, China
3.
Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education, Hunan University, Changsha 410082, China

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Received Date: September 03, 2023
Available Online: March 24, 2024

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Abstract

Abstract

The ultimate unloading ratio and the critical unloading ratio are the crucial parameters for determining the depth of disturbance below excavation base. The vertical unloading tests are performed on the Fujian sand and Fuzhou silty clay, with characteristic unloading ratios determined based on the normalized resilience value. The results indicate that the unloading response of soils changes in three phases. When the loading ratio is less than the critical unloading ratio, the response of soils can be ignored. Meanwhile, as the loading ratio exceeds the ultimate unloading ratio, the normalized resilience value and lateral pressure coefficient of soils increase rapidly, and the resilience modulus and shear modulus decrease significantly. Additionally, at this point, the horizontal residual stress ratio displays an inflection point and begins to decline. Furthermore, the test methods and the judgment criteria of characteristic unloading ratios are analyzed. The statistical mean values of the characteristic unloading ratios of clay, silt and sand in the unloading tests are calculated.
- excavation unloading,
- disturbance,
- unloading ratio,
- shear wave velocity,
- lateral earth pressure coefficient

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References

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