This paper presents a case study on the application of the vacuum preloadin
g method for a soil improvement project in Tianjin, China. The site area wa
s 50 000 m(2), and the soft clay treated was about 20 m thick, including a
very soft muddy clay layer 4-5 m thick, formed from dredged slurry. The wat
er contents of the clays were higher than or as high as the liquid Limits.
A vacuum load of 80 kPa was applied for 4 months. The ground settled nearly
one, and the average degree of consolidation was greater than 80%, The und
rained shear strength of the soil increased two- to three-fold after treatm
ent. The procedures used for soil improvement, the field instrumentation pr
ogramme, and the field monitoring data are described and discussed.