Experimental Study On Engineering Properties Of Lop Nor Sulphate Saline Soil

At present, the study of saline soil is relatively deep and extensive, especially for chlorine’scollapsibility and the sulfate’s salt expandability, and has established a comprehensive theoretical system,but the engineering properties of saline soil are very different in different parts, we should be subregionalresearch.Taking Lop Nor area of Sulphate (Sulfurous)saline soilas the research object,we have basicproperties,collapsibility,salt-frost heave test and further analysis the saline soil of collapsibility and thesalt-frost heave mechanism,then some conclusion are drawn.The collapsibility of sulphate (sulfurous)saline soilas test is using the uniaxial compression of doubleline method, we have the test on different dry density and different initial water contents.A conclusion wasdrawn that the coefficient of collapsibility of Lop Nor sulphate (sulfurous)saline soil decreased along withthe increase of water contents and dry densities, and coefficient of collapsibility increased along with theincrease of saltness.Sulfate (sulfurous) saline soil have peak pressure, before the peakpressure,collapsibility coefficient increases with pressure increasing; after the peak,collapsibility coefficientdecrease with the increase of pressure.Sulphate saline soil’s peak value is300kPa.sulfurous saline soil’speak value is200kPa,and the peak coefficient of collapsibility is generated at the peak pressure.Salt-frost heave test of sulphate (sulfurous)saline soil is under the freeze-thaw cycle condition,salinesoil sample deformation process is divided into three stages:the stage of salt expansion,the stage ofsalty-frost,the stage of thawing settlement. After7cycles of freezing and thawing cycle process, sulfate(sulfite)saline soil with freezing and thawing cycle times and initialwater content increasing, salt-frostheaving ratio increases;Under the same water content, with the initial dry density increased, salt-frostheaving ratio and the thawing settlement’s difference is not significant,water contents have greaterinfluence than dry desity to the salt-frost heaving;the more salt content have, the more salt-frost heave andthawing settlement have.Sulphate saline soil in third freeze-thaw cycle has the largest salt-frost heaving andmaximum thawing settlement increment, sulfurous saline soil in fourth freeze-thaw cycle has the largestsalt-frost heaving and thawing settlement increment.