Experimental study on the effect of moisture content on shear strength of unsaturated sandy soil

Abstract：In order to further study the effect of water content on shear strength of unsaturated sand, direct shear tests were carried out on six kinds of sands with the same dry density and different moisture content, by using DHJ50-2 cascade shear tester.The results showed that: (1) The change of sand moisture content caused the change of matrix suction in the soil, and then affected the cohesion of soil. (2) Under the low vertical load (100 kPa) , suitable moisture content (8%) hepled to improve shear strength of soil;the maximum shear dilation deformation (-2.32 mm) was produced while the cohesive force of sand was the minimum (37.10 kPa) . (3) Under the high vertical load (400 kPa) , the increase of water content reduced the internal friction angle of soil, and when the water content exceeded a certain value (>6%) , it had no effect on the internal friction angle.When the angle degree was the largest (39.68 °) , the shear deformation value was minimum (0.26 mm) .

Keyword：unsaturated sandy soil;direct shear test;water content;shear strength;shear deformation;mechanism of influence;