Influence of initial conditions on liquefaction resistance of silty sands

Abstract

The influence of initial conditions, i.e. stress state and void ratio, on the liquefaction resistance of silty sands under two-way cyclic loading is investigated in this paper. Using a cyclic triaxial test device, a series of undrained stress-controlled cyclic triaxial tests was performed on reconstituted specimens of sand and sand mixed with 15, 30 and 50% non-plastic fines content (finer than 75 μm). The sand samples were prepared at different void ratios of 0.915, 0.855 and 0.795. Sand–silt mixtures were formed at 40% relative density. Specimens were consolidated at different pressures of 50, 100 and 200 kPa and then subjected to two-way cyclic loading with CSR values varying in the range 0.075–0.275. Test results indicated that the compressibility and cyclic resistance of soil mainly depends on initial conditions and type of soil. A correction factor (K _σ) is considered to account for the influence of consolidation pressure on the liquefaction resistance of sand and sand–silt mixtures. The samples experience extensional strains in the case of low consolidation pressures and compression strains at high consolidation pressures. This behaviour is due to the increase in the contractive tendency of soil at high consolidation pressures.

Keywords:

• liquefaction
• non-plastic fines
• sand
• cyclic triaxial test