Laboratory study on the liquefaction resistance of sand-silt mixtures: effect of grading characteristics

摘要

The liquefaction susceptibility of saturated medium sand-silt mixture samples is evaluated by monotonic and cyclic undrained triaxial laboratory tests that were carried out on reconstituted specimens at various relative densities (D_r = 20,53 and 91 %) and a constant confining pressure (σ_3~'= 100 kPa). The test results were used to conclude on the effect of grading characteristics and other parameters on the liquefaction resistance of the sand-silt mixtures. The mono-tonic test results indicate that the undrained shear strength at the peak and the undrained residual strength can be correlated to the coefficient of uniformity (C_u) and the average diameter (D_(50)). Indeed, they decrease linearly with the increase of the uniformity coefficient and decrease of the average diameter. It is found that a relationship between the liquefaction resistance and any of the diameters (D_(10) or D_(50)) and the coefficient of uniformity (C_u) would be more realistic than to build a relation between the coefficient of gradation (C_c) and the liquefaction resistance. Undrained cyclic triaxial tests indicate that the cyclic liquefaction resistance of the sand-silt mixtures decreases linearly with the decrease of the effective diameter (D_(10)) and mean size (D_(50)) and increase of the fines content for the fines content range tested (Fc = 0-40%).