Experimental Study on Influence of Moisture Content on the Shear Strength of Unsaturated Compacted Soil

The shear strength of the compacted soil is obtained by direct shear experiments with different moisture content; the soil matrix suction is measured by the contact filter paper method, and the SWCC of the compacted soil is obtained; and the relationship between the matrix suction, cohesion and water content of the remolded soil near the optimal water content is studied based on the strength of attraction theory. The research results show that the matrix suction and moisture content curve is in the form of concave hyperbola, and the relationship with moisture content curve is a monotonous decreasing curve, the relationship between cohesion and moisture content is approximately parabolic, and the optimal moisture content corresponds to the cohesive force of the matrix is the largest; the conversion rate of matrix suction into suction stress gradually decreases with the increase of matrix suction. The soil moisture content in the high suction section is low, and the matrix suction is difficult to effectively transform into suction stress, leading to small cohesion.