Experimental Study On Lime-polyacrylamide Composite Flocculation-vacuum Preloading Reinforcement Of Dredged Slurry

With the rapid development of the southeast coastal economy,the demand for land is increasing day by day.At present,the traditional vacuum preloading method is used to treat the foundation in the domestic land reclamation projects.Due to the fact that the newly filled silt is often in a flowing state and there are a large number of very fine soil particles in it,the traditional vacuum preloading method is easy to produce silt blockage in practical engineering practice.As a result,the efficiency of drainage consolidation is low.Therefore,the traditional vacuum preloading method should be improved.In this paper,the polyacrylamide used in soil remediation and lime used in river silt treatment are used for reference,which are combined with vacuum preloading method to introduce them to the field of soft soil foundation treatment.Through the indoor model barrel test,the related mechanism and influencing factors are studied.The main contents are as follows:Firstly,the flocculation mechanism of organic-bound inorganic flocculant was described in view of the chemical reactions between lime bound anionic polyacrylamide,cationic polyacrylamide and non-ionic polyacrylamide with blowing silt.At the same time,the experiments of deposition,turbidity and permeability characteristics show that the lime combined with polyacrylamide can effectively increase the permeability coefficient of soil and reduce the existence of fine soil particles.It provides a theoretical basis for the experimental study of lime-polyacrylamide composite flocculation-vacuum preloading reinforcement of dredged silt.In addition,by means of the experiments of deposition,turbidity and permeability,the optimum addition of three kinds of polyacrylamide with different lime content was selected.It provides a reference for the test of the lime-polyacrylamide composite flocculation-vacuum preloading reinforcement of dredged slurry.Secondly,the consolidation and compression characteristics of three kinds of polyacrylamide treatment with different lime content were studied by consolidation test.Finally,the vacuum preloading test of six kinds of lime and polyacrylamide flocculant was carried out.The vacuum degree,displacement,pore water pressure dissipation and the changes of moisture content,cumulative settlement and shear strength of cross plate were observed and recorded in vacuum preloading test.By analyzing the change of these data,it is determined that the blowing silt treated with different lime content combined with three kinds of optimum polyacrylamide(PAM)can promote the vacuum preloading process under the action of vacuum preloading method.At the same time,through the comparison of the six groups of ratios,the range of matching combinations suitable for engineering practice is determined.