Study On The Influence Of Initial Water Content And Pore Water Chemical Composition On The Consolidation And Permeabilitity Characteristics Of Silty Silt

The water content and pore water chemical composition of dredged sludge in coastal areas are greatly affected by sedimentation,which have a great influence on the consolidation and permeability characteristics,and further affect the engineering characteristics of dredged sludge.Therefore,this paper carried out the experimental study on the influence of initial water content and the type and concentration of cations in pore fluid on the consolidation and permeability characteristics of dredged sludge under different consolidation pressures through consolidation and permeability tests,and analyzed the macro phenomenon of consolidation and permeability tests from a micro perspective by scanning electron microscopy,which has important guiding significance for the practical engineering in coastal areas.The main research results are as follows:(1)The compressibility increases with the increase of initial water content,and the permeability also shows similar laws with compressibility.The permeability coefficient decreases rapidly when the consolidation pressure is less than 200 kPa,and decreases slowly and tends to be stable when the consolidation pressure is greater than 200 kPa.The effect of initial water content on compressibility and permeability of dredged sludge can be converted to the effect of initial void ratio on compressibility and permeability.The empirical formula is fitted according to the relationship between void ratio and permeability coefficient.In the future,the void ratio of dredged sludge can be obtained directly through laboratory tests,so as to predict the corresponding permeability coefficient under the void ratio.(2)Pore ratio and liquid limit increase with the increase of cation valence or cation concentration,which leads to changes in compression and permeability characteristics of dredged sludge.When the consolidation pressure is small,the permeability of the high valence cation sample is higher than that of the low valence cation sample.With the increase of the pressure,the intersection occurs near 200 kPa.The permeability coefficient of the high valence cation sample is lower than that of the low valence cation sample,and the cation concentration is similar to the valence.From the pore index Iv,when Iv>-0.35,pore ratio is the main factor to control the permeability coefficient;When Iv<-0.35,cation type and concentration are the main factors controlling permeability coefficient.(3)Microscopic test results show that the pore distribution of dredged sludge with different initial water content has little difference after consolidation permeability test;The porosity of the high valence cation sample is larger than that of the low valence sample after consolidation permeability test,and the surface is rough.There are more white crystals precipitated,and the cation concentration shows similar laws.