Liquefaction and settlement characteristics of silt soils

An experimental investigation was made to ascertain the liquefaction (cyclic strength) behavior of loessial (silty) soils of low plasticity. This study is important in view of the seismicity of several regions of loessial deposits in the world.;The test program consisted of cyclic triaxial tests on remolded samples. The soil used in this investigation was from the vicinity of East Saint Louis, Illinois. The influence of parameters such as cyclic stress ratio, overconsolidation, plasticity index, coefficient of lateral earth pressure and water content on liquefaction susceptibility of a loessial soil of low plasticity has been investigated.;The test results indicated that repetition of cyclic loads to saturated samples of loess results in a build up of pore water pressure equal to initial effective confining pressure. The samples also underwent failure in terms of 5, 10, or 20 percent double amplitude strain. It was observed that the effect of increased plasticity reduced the liquefaction resistance of loessial soils of low plasticity, that the effect of overconsolidation increased the liquefaction resistance of loessial soils and that the effect of anisotropic consolidation could be explained in terms of the mean effective principal stress. A comparison was also made of the behavior of saturated loessial soil with that of a saturated sand and the difference in behavior of the two has been examined.