疏浚吹填泥沙静态间歇沉降行为及其稳态宏观评价标准

Static batch settling behaviors of dredged and filled sediment and its steady-state macroscopic evaluation criteria

关于疏浚吹填泥沙的静态间歇沉降行为与机理及其稳态宏观评价标准,目前暂未深入研究。这是当今疏浚吹填泥沙地基采用真空过滤排水固结技术进行处理时无法科学判断最佳启动时间的主要原因之一。鉴于此,先对疏浚吹填泥沙的静态间歇沉降行为进行理论研究,建立了颗粒悬浮液的沉降速度与平均孔隙比的理论关系式。然后,获取典型工程现场的疏浚吹填泥沙,配制典型浓度试样,开展静态间歇沉降模型试验研究。研究结果表明:(1)黏粒(d<0.005mm)含量是影响疏浚吹填泥沙静态间歇沉降行为与机理的关键因素之一;(2)颗粒通量最大值Gmax往往出现在试验难以测出的非常低的浓度条件下,且黏粒含量越高,越难通过试验方式测得;(3)对于黏粒含量为40%~60%的疏浚吹填泥沙,建议将“平均孔隙比累计变化率为60%~75%”作为静态间歇沉降稳定状态的宏观评价标准。

The static batch settling behaviors and mechanism of dredged and filled sediment and its steady-state macroscopic evaluation criteria have not been studied in depth yet.This is one of the main reasons why the optimal start-up time cannot be scientifically judged when the dredged and filled sediment foundations are treated by the vacuum filtration drainage consolidation technology today.In view of this,a theoretical study on the static batch settling behaviors of the dredged and filled sediment is conducted,and the theoretical relationship between the settling velocity of particle suspension and the average pore ratio is established.Based on the dredged and filled sediment from typical engineering sites and the configured typical concentration specimens,the experimental researches on the static batch settling model are carried out.The results indicate that:(1)The content of clay particles(d<0.005 mm)is one of key factors affecting the static batch settling behaviors and mechanism of the dredged and filled sediment.(2)The maximum particle flux Gmax often occurs at very low concentrations that are difficult to measure experimentally.The higher the viscous content,the more difficult it is to measure experimentally the maximum particle flux during static batch settlement.(3)For the dredged sediment whose clay content is within 40%to 60%,the cumulative change rate of the average porosity ratio of 60%to 75%can be taken as the criterion for evaluating the steady state of its batch settling process.