A series of studies have confirmed that vacuum preloading can effectively accelerate the consolidation process of soft soil. In recent years, further improvement in the efficiency of this method is still the continuing goal of scholars. This paper reviews the recent improvements in the vacuum preloading techniques as well as their practical applications in China. The advantages and disadvantages of each method are discussed. It is found that replacing or eliminating one or more components of the vacuum preloading system, such as sand-free, membrane-free, horizontal drain, multiple-step, and air booster vacuum preloading methods, achieved similar soil improvement effects to those of the traditional vacuum preloading method. Vacuum preloading combined with other soil improvement methods could improve the soil with the lower average water content and the higher average shear strength.

An interlocking L-shaped caisson (ILC) quay wall was proposed to improve the integrity of the caisson units by modifying the cross-sectional of the conventional L-shaped caisson (CLC) with two walls at its edge, shaped like a half hexagonal prism. A series of model tests were constructed to investigate the lateral stabilities of the proposed ILC quay wall by comparing with those of the CLC quay wall. Compared to the CLC quay wall, it was found that the critical bearing capacities of the ILC quay wall pinned by concrete blocks increased by 13% under strip load. The ILC quay wall demonstrates better structural integrity and load-bearing capacity. The plane strain method used in CLC quay wall design under concentrated loads overestimates the critical bearing capacity of the quay wall by approximately 47%. The lateral earth pressure on the caisson sidewall calculated using a modified Beton's method aligns closely with the average measured data. However, it underestimates the estimated value at a depth of 0.6 times the caisson height under concentrated loading.