Abstract：The model tests of vacuum preloading with flocculation (VPF) were carried out by applying the organic polymer flocculants APAM to the waste slurry produced from the construction of pile foundation in Shanghai. The anti-clogging mechanism in solid-liquid separation of waste slurry by VPF was also studied. It was found that (1) with VPF, the water content of waste slurry was reduced from 176% to 40%, while with the conventional vacuum preloading, the water content was reduced from 176% to 135%| (2) the drainage and consolidation effects due to three types of filtering membranes with O95=120/180/300 μm were all significant, implying that the dependence of clogging on different equivalent opening sizes of geotextile was not obvious and the anti-clogging effect was mainly attributed to additive agent| (3) Due to the adsorption-bridging effect of APAM, soil particles were joined together to form flocculation aggregate, playing a dominant role in anti-clogging process during vacuum preloading. Once the vacuum preloading was completed, the long-chain flocculation aggregates were broken and the distribution of particles recovered to the original state of waste slurry| (4) Conventional filter rule was inappropriate to VPF, due to the irregular chain of flocculation aggregates, and only the particle size index of aggregate may not actually reflect the filter characteristics.
