A method of determining nonlinear large strain consolidation parameters of dredged clays

A method of obtaining the large strain consolidation parameters of dredged clays considering the influence of the initial water content is investigated in this study. According to the test results of remolded clays with high initial water contents reported by Hong et al. （2010）, a relationship between the void ratio （e） and effective stress （a3 is established. Furthermore, based on the available permeability data from the literature, a new relationship between the permeability coefficient （k） and the ratio （e/eL） of the void ratio to the void ratio at the liquid limit （eL） is proposed. The new proposed expression considering the initial water content improves the e-k equation established by Nagaraj et al. （1994）. Finally, the influence of the initial void ratio and effective stress on the large strain consolidation coefficient g（e） defined by Gibson et al. （1981） and k/（1 ＋e） in large strain analysis is discussed. The results show that, under a constant effective stress, the value of k/（1 ＋e） increases with the initial void ratio. The large strain consolidation coefficient shows the law of segmentation change, which decreases with the increase of the effective stress when the effective stress is less than the remolded yield stress, but increases rapidly with the effective stress when the effective stress is larger than the remolded yield stress.

Consolidation behavior of Tianjin dredged clay using two air-booster vacuum preloading methods

This paper presents model tests(macro aspect)and microstructure tests(micro aspect)for investigating the consolidation behavior of Tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preloading(PAVP)and tube air-booster vacuum preloading(TAVP)methods.The mechanism of air-booster vacuum preloading(AVP)using a spring-like system is explained.The main difference between these two methods is the air-boosting equipment.A new anticlogging air-booster prefabricated vertical drain(PVD)is used in the PAVP technique and a self-designed air-booster tube is used in the TAVP technique.In the model tests,a comparison of the variables that are monitored during reinforcement(vacuum pressure,surface settlement,water discharge,and pore-water pressure)and after reinforcement(water content,dry density,and vane shear strength)is conducted.The results indicate that the consolidation behavior of Tianjin dredged clay using the PAVP method is better than that using the TAVP method.PAVP more efficiently mitigates the issue of water-draining PVD clogging and significantly accelerates drainage consolidation.In addition,in the microstructure tests,a comparison of the variables that are monitored after reinforcement(via scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP))is conducted,and the results further explain the model test results.