吹填土自重沉积固结特性试验研究

Laboratory study on self-weight sedimentation and consolidation behaviors of hydraulic-dredged mud

利用沉积柱试验研究了浙江海域沉积淤泥的自重沉积固结特性，探讨了泥水混合物初始密度、海水中阳离子类型及其浓度对自重沉积固结特性的影响。试验结果表明：该泥水混合物在50cm高的沉积柱中自重沉积阶段历时约3h，而自重固结阶段约持续到1～2d，自重沉积固结完成后的孔隙比介于2～3之间。泥水混合物的初始密度越大，泥浆自重沉积过程越慢，但固结完成后孔隙比越小。海水中盐溶液浓度越大或阳离子化合价越高，则泥浆沉积越快，固结后孔隙比越小。阳离子价位对该淤泥自重沉积固结特性的影响比溶液浓度更显著一些，在吹填工程实践中可考虑在泥水混合物中添加高价阳离子（如Ca^2＋）来提高自重固结速率和固结后密实度。该淤泥在0～2kPa应力范围的压缩曲线基本上是线性的，其对应的压缩系数约为1．3kPa^-1。

The consolidation behaviors of self-weight dredger-fill were studied by settling column test. The influences of initial density of soil-water mixture, concentration of electrolyte and type of cation in water on consolidation behaviors were investigated. The results showed that the duration for settling of sediment in the 50cm height column was about 3h, and the consolidation process lasted approximately 1-2 d. At the end of consolidation process, the void ratio was in the range of 2-3. The decrease of mixture initial density resulted in the increase both in settling speed and final void ratio. The higher concentration of electrolyte or higher valence of cation in water resulted in higher settling speed of sediment, and the final void ratio will be lower. The influence of cation valence on consolidation was stronger than that of electrolyte concentration. Consequently, the addition of high valence cation such as Ca^2＋ into soil-water mixture can improve the self-weight consolidation speed and density of consolidated dredger fill. The test result also showed that the compressive curve of consolidated dredger fill was linear within the stress range from 0 to 2 kPa.