Experimental study on undrained thixotropic cyclic resistance characteristics of marine soft clay

WU Qi; JI Dongwei; XIAO Xing; ZHU Shengdong; CHEN Guoxing

doi:10.11779/CJGE20230807

Volume 46 Issue 12

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Chinese Journal of Geotechnical Engineering > 2024 > 46(12): 2513-2520. > DOI: 10.11779/CJGE20230807

WU Qi, JI Dongwei, XIAO Xing, ZHU Shengdong, CHEN Guoxing. Experimental study on undrained thixotropic cyclic resistance characteristics of marine soft clay[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(12): 2513-2520. DOI: 10.11779/CJGE20230807

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Experimental study on undrained thixotropic cyclic resistance characteristics of marine soft clay

1.
Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing 210009, China
2.
Fujian Yongfu Power Engineering Co., Ltd., Fuzhou 350108, China

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Received Date: August 20, 2023
Available Online: March 24, 2024

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Abstract

Abstract

A series of unconsolidated undrained cyclic triaxial tests are carried out on the marine soft clay in the estuary of Yangtze River. The effects of age T, water content w and plasticity index I_P on the thixotropic cyclic resistance of the remolded marine soft clay are investigated. The test results show that the cyclic resistance CRR₁₅ for 15 cycles of the remodeled marine soft clay increases with T when the failure criterion is defined as the double-amplitude axial strain ε_ad = 5%, and the fastest growth rate of CRR₁₅ is observed when T = 14 d, and the CRR₁₅ increases slightly ortends to be stable when T > 28 d. The thixotropy of soft clay is weakened by early disturbance or cyclic loading, and the thixotropy cyclic resistance ratio A_d is obviously smaller than the static shear strength ratio A_s. A_d first increases and then decreases with the increasing I_P, but increases with the increase of w. A_d first increases and then decreases with the increase of the normalized water content w/w_L, an increase in the normalized water content w/w_L causes A_d to first increase and then decrease, and it reaches the maximum value when w/w_L = 0.76. The unconfined compressive strength tests under parallel test conditions are carried out, and the cyclic stress level is characterized by the ratio of the cyclic axial stress amplitude σ_d to 2 times the unconfined compressive strength q_u, σ_d/2q_u, and it is found that σ_d/2q_u is uniquely related to the failure cycle N_f required for the specimen to reach ε_ad = 5%, and σ_d/2q_u decreases as a power function with the increase of N_f.
- marine soft clay,
- cyclic resistance,
- water content,
- plasticity index,
- thixotropic cycle resistance ratio

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References

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