工程废浆处理过程中药剂真空预压法的防淤堵机理

选择有机高分子絮凝剂APAM作为药剂，进行室内药剂真空预压处理废浆的模型试验，探讨处理过程中药剂真空预压法的防淤堵机理。试验结果表明：①经药剂真空预压法处理工程废浆含水率由176%降至约40%，而经普通真空预压处理后工程废浆含水率由176%降至135%，药剂真空预压法处理效果非常明显|②药剂真空预压中采用了120μm、180μm和300μm三种不同等效孔径的过滤膜，发现三种过滤膜均能取得较好的效果，且结果相差不大，证明在药剂真空预压中改变等效孔径对防淤堵的影响不明显，其能够防淤堵主要是由于加入药剂改善了废浆性质|③加入药剂APAM后，由于吸附架桥作用土颗粒的粒径会增大而形成絮凝团聚体，在真空预压过程中发挥了很好的防淤堵作用，真空预压结束后连接团聚体的长链会断开，颗粒分布又恢复到接近原始废浆的状态|④常规反滤准则不再适用于药剂真空预压法，这可能与团聚体形状呈不规则的链状有关，仅仅用粒径指标并不能真实反映反滤特性。

Anti-clogging mechanism of vacuum preloading with flocculation in treating construction waste slurry

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.