真空负压下吹填淤泥排水固结动态淤堵特性研究

Clogging is a notable feature on drainage consolidation of dredged slurry under vacuum pressure. The dynamic clogging process renders that the treatment efficiency of the dredged fill in the reclamation tideland is not as expected. Based on the existing researches, the pattern of the soil particles’ movements and the forming process of the soil column by particle gatherings will firstly be investigated for the dredged slurry under the vacuum pressure, from a microscopic view on dynamic interactions between the pore fluid and the soil particles. Then the obtained microscopic variables are to be up-scaled to the compression and permeation properties of the clogging soil column, which enables a real-time reproduction of the macroscopic dynamic-clogging features of the soil column including the ever-growing of the column volume and the obvious decreasing both in the column compressibility and permeability. Based on the above studies, a hierarchical multiscale modelling method relying on the direct coupling of the microscopic soil-fluid interactions and the macroscopic seepage-consolidation theory, will be developed for studying the whole process of the drainage consolidation of the dredged slurry under a vacuum pressure. Both the micro- and macroscopic variables of the clogging soil column are to be obtained and investigated for the entire consolidation process. The dynamic clogging features for the drainage consolidation of the dredged slurry will be revealed in a directly-combined view from both of the micro- and macroscales. Lastly, the dynamic clogging features and the developed modelling method will be verified and improved by comparing to the in-situ test results. It is expected that the methods and results of this project can improve the understanding of the clogging effects on the drainage consolidation of dredged slurries, which will provide a reliable calculating method and effective theoretical basis for the efficient treatment of the dredged fills in the tideland reclamation practice.

淤堵是吹填淤泥真空负压下排水固结的显著特性，淤堵动态发展导致海涂围垦吹填地基处理工程效果不佳。针对现有研究的局限性，本项目拟从细观水土相互作用的角度，研究吹填淤泥土颗粒在真空负压梯度下的迁移运动规律和聚集形成土柱过程，将细观水土状态参量递阶为淤堵土柱的渗透压缩性状，实时再现淤堵土柱体积增长、土柱压缩性和渗透性显著下降的宏观动态淤堵性状。在此基础上，建立细观水土相互作用与宏观渗流固结理论的宏细观分层耦合计算方法，对真空负压下吹填淤泥排水固结全过程进行数值模拟和试验研究，分析淤堵土柱宏细观参量随固结过程的变化，细观和宏观尺度有机结合的揭示吹填淤泥排水固结的动态淤堵特性，最后通过现场试验进行验证和完善。项目的研究方法和研究成果可以加深对吹填淤泥排水固结动态淤堵效应的认识，可为海涂围垦吹填土地基处理提供计算方法和理论支持。

淤堵是吹填淤泥真空负压下排水固结的显著特性，淤堵动态发展导致海涂围垦吹填地基处理工程效果不佳。本项目制作了吹填淤泥真空预压粒子示踪模型试验系统，并采用CFD-DEM模拟淤泥和排水板滤膜，从细观水土相互作用的角度，揭示了吹填淤泥土颗粒在真空负压梯度下的迁移运动规律和聚集形成土柱的动态过程。本项目研发了一维真空过滤模型试验装置及其配套的参数拟合算法，获得了吹填淤泥幂函数形式的渗透压缩本构方程，发现了土柱压缩性和渗透性在低压力段的显著下降是导致宏观淤堵的关键。在此基础上，结合吹填淤泥土水两相介质的平衡、连续和运动等宏观物性方程以及土柱/淤泥边界和淤泥外边界移动方程，建立了能考虑淤堵土柱动态形成全过程的吹填淤泥排水固结计算方法，可成功分析土柱大小、渗透系数和孔隙比等参量随固结过程的动态变化，揭示了吹填淤泥排水固结的动态淤堵特性，理论分析结果与试验结果对比良好。本项目研究方法和研究成果加深了对吹填淤泥排水固结动态淤堵效应的认识，为海涂围垦吹填土地基处理提供了计算方法和理论支持。