Saturation Effect on Behaviour of Sandy Soil Under Monotonic and Cyclic Loading: A Laboratory Investigation

This paper presents a laboratory study of the influence of saturation degree on the liquefaction potential of sand. The study is based on drained, undrained monotonic and cyclic triaxial tests. Tests were conducted on a medium dense Hostun RF sand (France) with an initial relative density Dr = 4, 50, 64 and 78 % and the coefficient of Skempton ranging between 0.95 (saturated) and 0.25. For all Skempton’s coefficient B values, the tests were carried out for different loading levels. The monotonic tests show that an increase in the Skempton’s coefficient B leads to a reduction of liquefaction resistance. The decrement of the coefficient of saturation B does not affect the instability and steady state lines. The test results indicate that the liquefaction resistance increases with the decrease of Skempton’s coefficient B. For the high level of loading (RCC = 0.5), the number required to cause liquefaction varied little with the Skempton’s coefficient B (Nc = 9, 10 and 11 for B = 0.67, 0.36 and 0.25 respectively). For the low level (RCC < 0.40), the number of cycles needed for liquefaction increases susceptibly with the reduction of the coefficient of Skempton (B). A simple mathematical relation has been suggested to correlate the liquefaction resistance with the coefficient of Skempton B.