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Technical Improvements in Testing Small-Strain Deformation Behaviour of Frozen Soil
https://orcid.org/https://orcid.org/0000-0002-3752-7637
Small-strain modulus is an important parameter in engineering constructions such as tunneling employing artificial ground freezing method. Temperature and strain rate are two main factors influencing the small-strain deformation behaviour of frozen soil. Testing conditions and some technical cautions are crucial to the accurate measurement of the small-strain modulus. This paper reports an experimental study on small-deformation behaviour of clay frozen directly under confining pressure after being consolidated to different isotropic effective stresses. The loading probes were then conducted at three different axial strain rates (0.001, 0.01 and 0.1%/min) and three different temperatures (−10, −5 and −2 ℃). The freezing method, calibrating factor of local displacement sensor against temperature and loading approach with load cell outside the freezing chamber, was specially considered. The clay specimen was frozen under confining pressure to fully imitate the in situ freezing process. The adopted local gap sensor functioned well under different temperatures in the refrigerant, and the temperature effect on the calibration factor is negligible. After overcoming the error brought about by the external load cell, it is found that the small-strain modulus of frozen clay appears to be independent of strain rate. The samples frozen from higher effective mean stress state exhibited smaller initial stiffness.
Technical Improvements in Testing Small-Strain Deformation Behaviour of Frozen Soil
https://orcid.org/https://orcid.org/0000-0002-3752-7637
Small-strain modulus is an important parameter in engineering constructions such as tunneling employing artificial ground freezing method. Temperature and strain rate are two main factors influencing the small-strain deformation behaviour of frozen soil. Testing conditions and some technical cautions are crucial to the accurate measurement of the small-strain modulus. This paper reports an experimental study on small-deformation behaviour of clay frozen directly under confining pressure after being consolidated to different isotropic effective stresses. The loading probes were then conducted at three different axial strain rates (0.001, 0.01 and 0.1%/min) and three different temperatures (−10, −5 and −2 ℃). The freezing method, calibrating factor of local displacement sensor against temperature and loading approach with load cell outside the freezing chamber, was specially considered. The clay specimen was frozen under confining pressure to fully imitate the in situ freezing process. The adopted local gap sensor functioned well under different temperatures in the refrigerant, and the temperature effect on the calibration factor is negligible. After overcoming the error brought about by the external load cell, it is found that the small-strain modulus of frozen clay appears to be independent of strain rate. The samples frozen from higher effective mean stress state exhibited smaller initial stiffness.
Technical Improvements in Testing Small-Strain Deformation Behaviour of Frozen Soil
https://orcid.org/https://orcid.org/0000-0002-3752-7637
Small-strain modulus is an important parameter in engineering constructions such as tunneling employing artificial ground freezing method. Temperature and strain rate are two main factors influencing the small-strain deformation behaviour of frozen soil. Testing conditions and some technical cautions are crucial to the accurate measurement of the small-strain modulus. This paper reports an experimental study on small-deformation behaviour of clay frozen directly under confining pressure after being consolidated to different isotropic effective stresses. The loading probes were then conducted at three different axial strain rates (0.001, 0.01 and 0.1%/min) and three different temperatures (−10, −5 and −2 ℃). The freezing method, calibrating factor of local displacement sensor against temperature and loading approach with load cell outside the freezing chamber, was specially considered. The clay specimen was frozen under confining pressure to fully imitate the in situ freezing process. The adopted local gap sensor functioned well under different temperatures in the refrigerant, and the temperature effect on the calibration factor is negligible. After overcoming the error brought about by the external load cell, it is found that the small-strain modulus of frozen clay appears to be independent of strain rate. The samples frozen from higher effective mean stress state exhibited smaller initial stiffness.
Technical Improvements in Testing Small-Strain Deformation Behaviour of Frozen Soil
Lecture Notes in Civil Engineering
Petriaev, Andrei (editor) / Konon, Anastasia (editor) / Wang, Jinyuan (author) / Nishimura, Satoshi (author) / Joshi, Bhakta Raj (author) / Okajima, Shota (author)
2020-01-03
10 pages
Article/Chapter (Book)
Electronic Resource
English
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