Post-liquefaction settlement behavior of non-plastic silts

Soil dynamics was defined as a new research topic within the scope of geotechnical engineering along with raising awareness on liquefaction problem after 1906 San Francisco earthquake. Investigations after subsequent earthquakes (Alaska and Niigata, 1964; San Fernando, 1971;Kocaeli, 1999) revaled that soil liquefaction caused significant damages in superstructure and underground structures. For this reason, estimation of possible harmful effects and determination of the factors causing liquefaction is of great importance in geotechnical earthquake engineering. Recent studies on sandy and clayey soils which may be susceptible to liquefaction made prediction of behavior of these soils and subsequent probable settlements possible. Since relatively fewer studies were carried out on silt soils, a commonly accepted criterion concerning the liquefaction susceptibility and post-liquefaction settlements in these type of soils is not available, it is evident that more effort should be exerted on investigation of silt soil under seismic action. Understanding of above-mentioned behavior and creation of a database for use in engineering applications need further detailed studies. In this regard, this study aims to investigate the post-liquefaction settlements and liquefaction susceptibility of non-plastic silts. Therefore, a series of cyclic triaxial tests were performed on a saturated silt to make detailed investigations serving for previously mentioned purposes. The diameter and length of specimens were 50 and 100 mm, respectively. The specimens were prepared at increasing relative densities from 30% to 80% by increments of 10%. Before application of undrained cyclic loading, specimens were consolidated under an effective confining pressure of 100 kPa. Volume changes were recorded at the reconsolidation stage after loading. Results of experiments were used to evaluate the effects of excess pore water pressure, cyclic stress, cyclic stress ratio and shear strain parameters. Additionally, correlations were obtained between factor of safety against the liquefaction, post-liquefaction settlements and relative density, for prediction of post-liquefaction behavior. Results were presented in detail for evaluation of pre and post-liquefaction behavior of non-plastic silts.