吹填淤泥堆场颗粒分选特性及其机理研究

It is difficult to assess accurately the storage capacity of storage yard and reasonably chose the method of rapid consolidation treatment programs when the physical and mechanical properties of dredged slurries in the yard uneven distribution caused by grain sorting during hydraulic fill. It is a core scientific problem to understand the grain sorting behavior and mechanism of dredged slurries in reclaimed land. The grain sorting behavior of dredged slurries and the effects of initial water content, soil properties and flow rate on it will be revealed in this project by the model tests, laboratory tests and theoretical analysis. Based on the Mechanics of sediment transport and High of sands contained stream flow to the kinematics, the mechanism of grain sorting behavior of dredged slurries in reclaimed land will be clarified. An effective method which coupled the effect of initial water content, soil properties and the fill rate of dredged slurries, on forecasting the distribution of soil particles in reclaimed land, will be established. And this method will be verification based on data of particles distribution obtained from the actual land reclamation engineering. The findings of this research can make up the limitation on the lack of understanding the grained sorting behavior, mechanism and prediction method on distribution of particles in reclaimed field. This program will also provide a theoretical foundation for the accurately assessing the storage capacity of yard and reasonable choice the method of rapid consolidation treatment programs in hydraulic reclamation engineering.

吹填淤泥在吹填过程中发生颗粒分选，导致其物理力学特性在堆场中分布不均，因而影响堆场储存能力的准确评估和快速固结处理方案的合理选择，揭示吹填淤泥在堆场中的颗粒分选机理并掌握其变化规律是解决这一难题的核心科学问题。本项目采用模型试验、室内试验、理论分析等方法进行堆场吹填淤泥颗粒分选特性研究，探索初始含水率、土性、吹填速率等因素对颗粒分选的影响，揭示吹填淤泥堆场颗粒分选特性。以泥沙运动力学及高含沙水流运动学为理论基础，阐明流速梯度、流体类型等对颗粒分选的影响，揭示吹填淤泥堆场颗粒分选的机理。耦合初始含水率、土性、吹填速率的影响，建立堆场吹填淤泥颗粒分布定量化预测方法，针对实际工程进行堆场调查，验证预测方法的有效性。本项目的研究成果可弥补目前对吹填淤泥堆场颗粒分选规律及其机理缺乏认识和缺少吹填淤泥堆场颗粒分布预测方法等局限，为吹填工程中准确评估堆场储存能力和合理选择快速固结处理方案提供理论依据。

无论是内陆还是近海岸的吹填工程，均涉及到有效利用堆场及后期加固方案选择的问题。了解堆场中动水环境下吹填淤泥的颗粒分选规律，对堆场的利用效率及吹填淤泥处理方案的选择都具有十分重要的意义。本文通过开展室内试验、模型试验及现场调研等，旨在揭示动水环境下吹填淤泥在堆场中的颗粒分选特性，分析初始含水率、土性、吹填速率、流速梯度等对堆场颗粒分选规律的影响,阐明动水环境下颗粒分选的影响机理，获得如下成果：明确了吹填淤泥初始含水率和土性、级配等因素对于吹填淤泥流体类型的影响规律，当泥浆初始含水率较低时，疏浚泥的流动可视为宾汉体，当泥浆初始含水率较高时，可将疏浚泥视为牛顿体，两者间的临界状态在5倍液限左右，提出了吹填淤泥屈服应力和塑性粘度的预测公式。分析了动水环境下，流速梯度对于淤泥沉积过程中浊液面的形成与沉降速率、含水率及各粒组相对运动规律的影响，明确动水环境下，吹填淤泥沉积过程中沿高度可分自上而下可分为悬浮层、含水率过渡层，含水率稳定层等三个部分；揭示流速梯度对絮凝结构（集合体）不同程度的破坏及小于0.01mm 的颗粒在流速梯度作用下的絮凝与大于0.01mm 的颗粒运动速度的差异等是颗粒分选发生的机理。采用分选度对吹填淤泥吹填过程中颗粒分选程度进行定量化研究，明确土样液限小，越容易分选，吹填速率越高，分选度越小；泥浆初始含水率越高，分选度越大。当液限高于60%或初始含水率低于5倍液限时，分选特性较弱。基于吹填模型试验数据，采用多元回归分析方法，建立了考虑吹填过程中泥浆流量、相对含水率的吹填淤泥粘粒含量与距吹填口距离关系的量化预测方法。通过现场调研数据的比较，验证了预测方法的可靠性。本项目的研究成果将为沿海开发及南水北调等工程中吹填淤泥的堆场设计及快速固结方案的确定等提供有效的颗粒分布预测方法。因此，具有具有巨大的经济价值和社会民生意义及良好的应用前景。