Study On Subgrade Water And Salt Mingration Law And Cut Off Layer Setting Technology In Qarhan Salt Lake Area

In Qarhan Salt Lake area, there is a large number of over-saline soil, the groundwaterlevel there is very high, therefore, water and salt migration which are caused by capillaryaction can easily lead to subgrade disease such as karst depression、frost heave and frost boil.Through the self-design test equipment and laboratory test, the migration law of the water andsalt under the brine is studied, the effectiveness that different cut-off layers prevent water andsalt migration is explored.The main results are listed as following:1. According to the standpipe test principle, combining with characteristics of plexiglasssuch as plasticity、high strength、high transparency, the standpipe test was built, the diameterof which ranged from20to30cm. Large caliber could truly reflect the actual situation,circulating water kept the surface stable, heavy compaction test guaranteed of the degree ofcompaction, direct observation recorded the rise of the water.2. By laboratory test, the water and salt migration law in non-salinized silt、weak salinesoil、well-graded gravel and gravel are reached, the rising level and salinization level ofcapillary water in different kinds of soils are fixed.3. Through test, the water and salt migration law in non-salinized silt、well-graded gravelunder different cut off layer setting are studied, the effectiveness of different cut off layersetting is evaluated and analyzed. Referencing to subgrade fill and height, the way of settingthe cut off layer is put forward.4. The cut off layer setting technology in well-graded gravel、non-salinized silt and weaksaline soil are proposed, combining the problems of paving process in the test road, specificsolutions are offered.