分级真空预压法处理疏浚淤泥的三维数值分析

Three-dimensional Simulation of Dredged Silt Treated by Hierarchical Vacuum Preloading

为探究分级真空预压法的加固机理与颗粒迁移规律,采用颗粒离散元软件建立三维数值模型,分析了分级真空预压法处理过程中不同时刻的土颗粒分布与移动速度情况,并对处理后土体中不同位置处的孔隙率与黏粒含量进行分析。结果表明:真空预压法处理疏浚淤泥过程中土颗粒会向排水板迁移,采用低真空度能减缓颗粒迁移现象;分级施加真空度能减缓土体孔隙率的下降速度,土体排水通道畅通,更有助于分级真空预压法排水加固土体;颗粒迁移过程中,靠近排水板处的黏粒含量会增加,而分级真空预压法能减少细颗粒的迁移,其中分三级施加真空压力的方式能最大程度降低细颗粒迁移数量,有助于缓解淤堵层形成,提高土体排水效率,增加土体加固效果。

To explore the reinforcement mechanism of hierarchical vacuum preloading method,the particle discrete element software was used to establish the three-dimensional numerical model,and the classification of vacuum preloading method during the processing of the soil particle distribution and movement speed of different times were investigated.The processing of different location of soil porosity and clay content were also analyzed.The numerical simulation results show that the soil particles migrate to the drainage plate in the process of vacu‐um preloading,and the phenomenon of particle migration can be slowed down by using low vacuum degree.The vacuum degree applied by stages can slow down the decreasing speed of soil porosity,and the drainage channel of soil is unblocked,which is more helpful to the drainage of soil by stage vacuum preloading method.In the process of particle migration,the content of clay particles near the drainage plate will increase,and the hierarchical vacuum preloading method can reduce the migration of fine particle.The three-stage vacuum pressure method can minimize the number of fine particles migration,which is helpful to alleviate the formation of blockage layer,improve the drain‐age efficiency of soil,and increase the reinforcement effect of soil.