To analyze the impact of particle composition on reinforcement of dredger fill under vacuum preloading from the aspect of meso-scale mechanism,we carried out a laboratory vacuum preloading model test on one group of samples from Binhai New Area in Tianjin using the particle flow method for simulation;then simulated six groups of samples with different grain size distributions under the same loading condition.The changes of drainage rate and deformation were analyzed.The results show that the two-dimensional particle flow method is effective for the simulation of laboratory vacuum preloading tests.Fine particles penetrated along the migration path with some detained along the way so that the penetration path became narrower and shorter.As for the newly-dredged fill with high clay content under the same loading condition,the initial drainage rate grew faster with the increase of clay content,and decayed faster with the increase of uneven coefficient;while the higher the silt content,the more uniform the porosity of soil at different position,especially,when the silt content was higher than the clay content,and the effecter of vacuum preloading.%为了从宏观和微观角度探讨颗粒组成对淤堵层形成机理和加固效果的影响规律,依托天津某新近吹填造陆工程,先进行直排式真空预压法室内模型试验,然后基于颗粒流理论和PFC2D程序,在解决模拟过程中颗粒级配和孔隙比的二维转换、排水边界的等效模拟、真空渗流场的施加等问题后,对模型进行有效的模拟计算,进而将结果推广,开展了不同颗粒组成吹填土真空预压试验的颗粒流模拟,总结了排水速率变化及颗粒运移规律.结果表明:对吹填土真空预压过程进行二维颗粒流数值模拟是有效可行的;真空预压过程中细颗粒沿渗透路径迁移,在沿途滞留,导致渗透路径变短变窄,从而形成淤堵层;对于高黏性新近吹填淤泥,在相同真空荷载作用下,黏粒质量分数越大,初期排水速率增长越快,并且随着土体不均匀系数的提高,淤堵层变得易于形成且致密,排水速率衰减越快;粉粒质量分数越大,土体孔隙率变化越均匀,尤其当粉粒质量分数大于黏粒质量分数时,真空预压加固效果有明显改善.
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