Dredged soil in the Leqing Bay area of Zhejiang Province has the characteristics of high pore ratio,high clay content,high moisture content,high thixotropy,low shear strength,and slow drainage.Its engineering properties are poor,and reinforcement is difficult.Combining with a vacuum preloading project in the north port area of Leqing Bay reclamation area,we set up four 3 000 m2 vacuum preloading test areas to study the differences in reinforcement effects of different plastic drainage plate spacing and models under the same vacuum degree,and analyze the reinforcement effect through monitoring data such as membrane vacuum degree,surface settlement,pore water pressure,as well as detection results of soil moisture content and vane shear strength.Then we analyze the dispersion of physical and mechanical indicators of unstructured dredged soil based on a large amount of testing data on moisture content and vane shear strength in the test area,and provide suggestions for reasonable acceptance indicators after reinforcement.The results show that when using vacuum preloading to reinforce ultrafine particle unstructured dredged soil,there is no significant difference between A-type and B-type plates for shallow reinforcement,and the improvement of reinforcement effect is not significant when the spacing between plastic drainage plates is less than 100 cm.After the reinforcement of unstructured dredged soil,the mechanical indicators are relatively discrete while the moisture content indicator is relatively stable.It is recommended to use the moisture content as the acceptance indicator.It is recommended to use the three-phase composition of the soil to calculate the compression ratio and settlement of unstructured dredged soil.