吹填淤泥固结泥-土转化规律及简化固结模型

The key to the reclamation technology is to improve the consolidation rate of the dredged slurry featured by high water content and compressibility, the prerequisite of the technology is the well understanding and prediction of the consolidation behavior of the dredged slurry featured by the transformation of the mud-soil mixture. It is proposed to conduct the elemental tests with multiple stress levels to define the critical effective stress for identifying the "viscous mud" and "Terzaghi soil" and the approach to obtain it. In order to clarify the principle of the mud-soil transformation and mud-soil interface movement, the development and relationship of the consolidation behavior, effective stress and void ratio are analyzed by conducting the consolidation model tests under different initial and boundary conditions. Based on the above results, a multiple-phase 1D consolidation model considering the non-linear compression and permeability constitutional law at the respective mud and soil stages is developed. The project could reveal the formation process of the soil structure and the progressive consolidation mechanism of the dredged slurry. It could provide a new methodology for studying its consolidation behavior. Moreover, it offers key computation parameters and theoretical support for the design of the dredged slurry foundation.

利用吹填淤泥造地技术关键在于如何加速高含水量、高压缩性的淤泥地基排水固结，而解决此关键技术的前提是对吹填淤泥以泥-土转化为主要特征的固结性状的正确认识与预测。本项目拟针对高含水率吹填淤泥，通过开展多级应力水平的单元体固结试验，分析固结过程中泥、土两相固结性状的差异，探讨界定“粘滞泥”和“太沙基土”的临界有效应力及其试验获取方法。通过开展不同初始、边界条件的固结模型试验，分析土体固结性状、有效应力及孔隙比的演化过程及相互关系，揭示吹填淤泥固结过程中泥-土转化规律及泥-土界面运移规律。基于试验结果，建立分别反映泥、土相压缩固结本构关系的分段简化一维固结模型。本项目可揭示吹填淤泥的泥-土动态结构形成及渐进固结机理；为其固结性状研究提供新思路；并为吹填淤泥地基加固设计提供关键固结参数和理论支撑。

利用吹填淤泥造地技术关键在于如何加速高含水量、高压缩性的淤泥地基排水固结，而解决此关键技术的前提是对吹填淤泥以泥-土转化为主要特征的固结性状的正确认识与预测。通常的计算方法是基于土体固结特性为常数或线性变化等简化条件，很难反映吹填淤泥这种泥—土混合大变形体在固结过程中压缩渗透特性的高度非线性特征。而固结性状具有显著差异的“粘滞泥”与“太沙基土”的动态转化运移是造成吹填淤泥固结性状高度非线性的重要原因。.本项目针对高含水率吹填淤泥开展了宽幅有效应力区间多级单元体固结试验，试验结果表明：e-lgp曲线形状呈现明显的反S型且存在明显的转折点，相应含水率位于液限附近。通过分析试样的e-lgp曲线界定了“粘滞泥”和“太沙基土”的临界有效应力。开展了不同初始、边界条件的固结模型试验，分析了土体固结性状、有效应力及孔隙比的演化过程及相互关系，试验结果表明：超软土在一维固结初期表现出显著粘滞流体的特性。土样排水边界附近的“泥”最先转化为“太沙基土”；“太沙基土”壳层逐渐增厚，“泥土混合体”的固结速率则主要由渗透系数较小的“太沙基土”来控制，土样固结速率显著减小。固结试验成果表明超软土样在0-2 kPa 的低有效应力区间和60-80 kPa 有效应力区间的固结系数及渗透系数的相差达2~3 个数量级，表现出明显的二段式非线性固结特性。基于试验结果，建立了分别反映泥、土相压缩固结本构关系的二段式简化一维固结模型。固结模型所需的泥、土阶段的固结系数、渗透系数等计算参数可通过前述多级单元体固结试验获取，计算参数具有明确的物理意义，且可考虑土体应力—应变以及渗透非线性特征。本项目揭示了吹填淤泥的泥-土动态结构形成及渐进固结机理，并为吹填淤泥地基加固设计提供关键固结参数和理论支撑。