Abstract
Frictional resistance between dry sand and mild steel is studied by laboratory experiments. The significance of possible influential factors is examined with the use of the experimental design method. The considered factors include surface roughness of steel, 50 percent diameter of sand, sand type, test type (simple shear and shear box), and uniformity coefficient of sand. Among the factors, the surface roughness of steel, 50 percent diameter of sand, and sand type are found to have significant influence on the coefficient of friction. In order to evaluate the angularity of sand particles, modified roundness of sand was measured. Normalized roughness is proposed to evaluate the relative roughness of sand-steel interface. Coefficient of friction at yield show good correlations with normalized roughness. Coefficient of friction is estimated as a function of modified roundness and normalized roughness. The estimation of coefficient of friction showed good agreement with measured values.
