Influence of cyclic deviator stress and consolidation degree on permanent strain of “under-consolidated” marine sediment

Abstract

Rapid rates of clay sedimentation produce a highly hazardous marine foundation condition: “under-consolidated” marine sediments. Numerous traffic infrastructure facilities have been constructed on this type of clay. In this study, a series of original cyclic oedometer tests were performed to investigate the drained long-term permanent strain of soft marine clays. The stress–strain relationships and permanent strain accumulations of the clay specimens were evaluated and compared under different cyclic stress ratios (CSR_s) and consolidation degrees (U_s). First, when CSR_s increased, the total strain also increased; however, its rate of increase decreased at higher CSR values. Thereafter, we derived a new threshold value as the upper boundary of the CSR for pavement designs on soft clay foundations. When the CSR was below this threshold value, the accumulated permanent strain increased rapidly with an increase in the CSR; when the value was surpassed, the strain accumulated slowly and was approximately linear as the CSR increased. Finally, equations for predicting the long-term permanent strain of under-consolidated clays were established. The findings of this study will serve as a useful technical reference for researchers and engineers in the field of land reclamation, thereby helping ensure the safety and durability of current and future public infrastructure facilities constructed on such lands.

Keywords:

• Under-consolidated marine sediment
• consolidation degrees
• threshold cyclic stress ratios
• long-term permanent strain

Disclosure statement

On behalf of all the authors, the corresponding author states that there are no conflicts of interest.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grants 51978534 and 51778502, National Nature Science Foundation Projects of Zhejiang Province (No. LR18E080001), and Key Research and Development Program of Zhejiang Province (No. 2018C03038).