An Experimental Research On Physical And Mechanical Characteristics Of Red Clay Polluted By NaCl

Environmental issues become increasingly prominent as industrial and urban development speed up.As such,the rock soil environment has been also affected and thus geo-environment engineering catches much concern.Red clay at Lingui,Guilin serves as the object of the study and NaCl liquor as the source of pollution.The experimental study of basic physical and mechanical of the red clay polluted by NaCl liquor is carried out by basic physical experiments,experiments of solid physics,direct shear tests and triaxia tests.Main contents are listed as follow:?1?Basic physical property tests including experiments of moisture content,quality,density,specific gravity,void ratio,liquid-plastic limit and chemical elements.Study findings show that SiO₂,Al₂O and Fe₂O₃ are the main oxides in the red clay for study and illite stands as the main clay minerals.As the density of the NaCl increases,the content of the oxides reduces gradually.Basic physical properties of the polluted lay are totally different from those when the clay is pollution free.As the density of the liquor increases,the quality,density,and specific gravity of the polluted red clay grows to varying degree respectively while moisture content,void ratio,liquid-plastic limit and plasticity index decrease in varying degree.?2?Findings of consolidation tests:e-p of the red clay samples embodies common features of the common red clay;three polluted red clay samples of compaction degree show that compression increases as the density of NaCl increases;compression coefficient of the clay grows but modulus of compression gradually decreases as the density of the liquor raise;samples with the same density of NaCl has a decreasing compression coefficient and a growing compression modulus as the compaction degree strengthens,which demonstrates that a growing compaction degree can,to a certain degree,resist the erosion of the NaCl liquor.?3?Findings of direct shear tests and triaxia tests:under the condition of the same normal stress,red clay samples with the same compression degree have a gradual decreasing shear strength as the density of the NaCl liquor increases and have a increasing shear strength as the compaction degree increases.The cohesive force and internal friction angle of the samples decrease on the whole while there is a small growth of the angle within the density range of 13.5percent to 18.5 percent;the stress-strain curve of the polluted red clay shows a strain hardening tendency;as the density of the NaCl liquor adds up,the principle stress deviator peak of the samples drops in general but with a small recovery with the liquor density at 18percent;the principle stress deviator peak of samples with a density of NaCl liquor peaks up as the confining pressure enhances.?4?Reasons for the emerging of findings mentioned above:NaCl liquor enters into the inner part of the red clay and reacts physically with substance in the inner part of the red clay.As such,minerals,chemical components and cementing materials in the clay changes,thus the inner structure of the clay is destroyed.Through ionic reaction,ion enters into hydrated film and changes the thickness of the film and thereafter changes the density of the porosity fluid in the inner side of the clay.Thus interaction force between soil particles is affected and thus changes physical and mechanical properties of the clay samples.