A LABORATORY TEST STUDY ON WATER AND SALT MIGRATION IN NATURAL SALINE SOILS AND ASSOCIATED SHEAR STRENGTH CHANGES UNDER FREEZING AND THAWING CYCLES

Through the conventional laboratory testing of saline soil samples collected from twelve different places(Kashi,Sinkiang,P.R.China), the representative crude saline soil samples were selected for the experiment of freezing and thawing cycles in open systems.Moving patterns of water and solute migration and variations of shear strength of the representative crude saline soils were studied for different kinds of soils.The result of the tests shows that moving patterns of water and solute in low liquid limit clay under several freezing and thawing cycles are generally consistent with water and solute migrating upwards.The distribution of cohesion of low liquid limit clay decreases linearly form bottom to top and the distribution of the internal friction angle is in s-shape.Both the water and the solute in low liquid limit clay with sand move to the cold end under freezing and thawing cycles and the profile of ion indicates higher concentration in middle than in both ends.The distribution of cohesion of low liquid limit clay with sand is in reverse s-shape,while the distribution of internal friction angle is in s-shape.