Lime Flocculation Combined With Vacuum Preloading For Improvement Of Dredged Slurry

With the proceeding of land reclamation,large amount of dredged slurry need to be treated by vacuum preloading before used for any constructions.Because the dredged slurry mainly consist of fine particles,clogging always occurs during the conventional vacuum preloading,leading to a low efficiency of vacuum preloading and a series of engineering problems.Thus,it is imperative to improve the vacuum preloading and vacuum preloading combined lime treatment was proposed.However,since the poor mechanism of this method,the factors that influence the efficiency of this method is still not clear,so the investigation about this method need to be carried out.This paper present the basic mechanism of vacuum preloading combined with lime treatment based on lime-clay reactions,and the related mechanism and factors that affect this method were studied.The main content includes follows:Firstly,based on the lime-clay reaction,the mechanism of flocculation by lime was studied and settlement tests and consolidation tests were conducted.The results showed that lime would reduce the settlement time of slurry and rise the void ratio of the dredged slurry.Then to investigate the influence of initial water content of dredged slurry on the optimum lime content,a pilot trial of vacuum preloading was carried out.In this trial,dredged slurries with two different water contents,125%and 155%were employed,and these slurries were mixed with five different lime contents,0%,1%,1.5%,2%,2.5%respectively.The results showed that the optimum lime content for the dredged slurry with the initial water content of 125%and 155%are 1.5%and 2%respectively.And it indicated that dredged slurry with low initial water content need a lower lime content.Finally,the flocculation by lime and natural condition was compared.Lime flocculated dredged slurry,natural slurry and natural flocculated slurry were utilized and vacuum preloading was also applied on all slurries.The results showed that the efficiency of lime flocculation was better than natural flocculation.