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Xinjiang University (2021)

Characteristics of Soil Salt Crust Formed by NaCl,Na2SO4 and Its Mixed Salt with Aeolian Soil from Gurbantunggut

李胜辉

Titre : Characteristics of Soil Salt Crust Formed by NaCl,Na2SO4 and Its Mixed Salt with Aeolian Soil from Gurbantunggut

Auteur : 李胜辉

Grade : Master 2021

Université : Xinjiang University

Résumé partiel
Sandy desertification is an important part of desertification,which has caused serious damage to the ecological environment in northwest China.Moving sand dunes will not only lead to the inundation of villages,farmland and roads,but also cause large-scale sandstorms,which will cause great harm to the transportation of sand areas and to the agriculture of oasis areas.Therefore,the prevention of sandy flow is an urgent ecological problem.Soil salt crust can change the loose structure of sandy soil,improved the resistance of sandy soil to wind erosion,contained the flow of sandy soil.Three kinds of ions(Na+,Cl-,SO42-)with higher content in sandy soil were selected for this salt crust experiment.It was set six salt concentration gradients,which was 0.1,0.5,1,1.5,2,2.5 mol/L in the experiment,and set eleven salt mix ratios(NaCl:Na2SO4),0:10,1:9,2:8,3:7,4:6,5:5,6:4,7:3,8:2,9:1,10:0,respectively.The following conclusions were obtained:1)The compressive strength of NaCl,Na2SO4and mixed salt crust were affected by salt concentration,salt type and crystal morphology.When the salt concentration was low,the volume of crystals deposited on the sandy soil particles was small,and the crystals spoted on the surface of aeolian soil particles.The compressive strength of the salt crust was increased by the increasing friction force between aeolian soil particles caused by salt crystals deposited on the sandy soil particles.When the salt concentration was≧1.5 mol/L,the compressive strength of three salt crusts had different trend curves with the salt concentration increasing.The compressive strength of NaCl crust increased with the salt concentration increasing,and NaCl crystals deposited in the salt crust were cubic or cluster ;the compressive strength of Na2SO4crust decreased with the increasing of salt concentration,and Na2SO4crystals in the salt crust were needle,rod,hairy globular and other,crystals destroyed the salt crust ;the compressive strength of mixed salt crust is a waving curve with the salt concentration increasing,the crystal’s shape was more complex in the mixed salt crust

Mots clés : salt crust ;compressive strength ;microstructure;wind erosion resistance ;

Présentation (CNKI)

Page publiée le 15 mars 2022