Study On Salt Expansion And Frost Heave Deformation Mechanism Of Saline Soil Subgrade In Southern Xinjiang

Southern Xinjiang city of asphalt concrete road because of the influence of saline soil subgrade,deformation and failure will happen in the winter and spring were each year, serious impact on the local traffic conditions; The government every year to repair the road, road surface deformation destroying this to a certain extent, restrict the local economic development.Through to the Southern Xinjiang city road damage types of survey analysis: Southern Xinjiang seasonal damage of asphalt concrete are mainly roadbed in salt- caused by frost heave deformation. Different locations in Southern Xinjiang major cities stratified sampling, salt category analysis, several major cities in the southern border saline soil type is given priority to with chlorine saline soil and sulphate saline soil.In order to explore the Southern Xinjiang asphalt concrete road salt and frost heaving deformation mechanism of Southern Xinjiang Alar hongqiao road extension is chosen as the research object, on the experimental study for a period of more than two years, the main research contents and results:(1) Through to the subgrade as the classification analysis, draw the subgrade for chloride, sulphate saline soil saline soil type.(2) In the laboratory to test study of saline soil subgrade, it is concluded that the liquid limit index is9.6, the plastic limit index is 0.13, belong to sandy silt soil samples, hard plastic; Through the compaction test, it is concluded that the best moisture content is 20%, the maximum dry density of 1.68 g/cm3; By shear strength test, learned that moisture content of soil sample must have, the greater the dry density of soil samples, the higher the shear strength of the soil; Dry density is constant, with the increase of moisture content, the shear strength of the soil has a tendency to decrease; Through the freeze-thaw cycle test, salt expansion has learned that the cumulative effect, and the frost heave the cumulative effect is small; By single factor under the changing temperature and salt- frost heave test, step by step that saline as- frost heave deformation and salt content, moisture content, temperature, degree of compaction and other factors.(3) The whole structure damage of pavement subgrade layer drilling sampling, make sure of the water in the subgrade soil stability as the main damage layer; Green belts in the subgrade soil of different depth and corresponding soil sampling and experimental analysis, the damage of main salt for chloride salt and sulphate; Through long-term monitoring for roads, and found that the vertical deformation and roadbed road temperature, daily average temperature in different depth, ground water level change, closely related to subgrade moisture content.(4) Through the experimental research on the deformation in the southern Xinjiang city road of Saline Soil Subgrade Frost salt expansion, and puts forward prevention measures.