Experiment Study On Improvement Effect Of Biopolymer For Drainage Consolidation Of High Water Content Silt Soil

There is a large number of silt with high water content in coastal areas of our country,including natural soft soil and artificial dredged slurry,which need to be improved before they can be used in engineering construction.However,because of clogging,the traditional drainage consolidation method is not effective and needs to be assisted by other methods such as flocculation or eletroosmotic.Biopolymers are microbial-induced polymers with high strength,non-toxicity,and environmental protection.The interaction of soil-biopolymers and related soil reinforcement mechanisms have recently been studied by scholars.In order to build an environmentally friendly society and achieve carbon neutrality,this article focuses on biopolymers replace traditional flocculants to improve the effect of drainage consolidation methods on the silt with high water content.The main contents are as follows:（1）Basic property of silty soil with high water content were studied.The loading-unloading K₀ consolidation test was carried out according to the influence of soil stress history on the coefficient of soil lateral pressure.It was found that the lateral pressure of over-consolidated soil was higher than that of normal consolidated soil.The unloading coefficient obtained by Mayne and Kulhawy model was more suitable for Schmidt’s empirical formula,It can accurately simulate the side pressure coefficient of silty soil,the relevant results can be used for cofferdam design and support calculations in tidal flat reclamation areas.（2）Six biopolymers（guar gum,locust bean gum,xanthan gum,chitosan,carboxymethylcellulose sodium,sodium alginate）and high water content silt were mixed for suction filtration and deposition tests.It was found that all six biopolymers had good flocculation effects.Guar gum,locust bean and chitosan performed better in were on reducing the suction filtration time.When 0.2%guar gum was mixed,the suction filtration result was the best.At the same time,it was found that an excessively high mixing ratio would reduce the permeability of the soil and show negative impact on filtration.（3）Guar gum,locust bean gum,and chitosan were used as flocculants in the flocculation-vacuum model test.Flocculation of these biopolymers speeded up the drainage rate in consolidation,reduce the working time of vacuum preloading,and increase the penetration strength of the soil after the test.By changing the mixing method of polymer,it was certified pouring the polymer and the slurry with high water content（200%～300%）simultaneously can achieve the uniform mixing and flocculation effect better compared with directly adding the polymer solution to the surface of the soil.（4）Indoor electroosmosis consolidation test was carried on mixture of six biopolymer silt.The efficiency of electroosmosis drainage of the soil applied by biopolymers was obtained It was found that the electroosmotic effect of sodium carboxymethylcellulose was the best.Compared with the untreated group,the final drainage volume of pore water increased by20.54%,the energy consumption was reduced by 11.59%,and the average bearing capacity grew up by 68.23%.