Small-strain behavior and post-cyclic characteristics of low plasticity silts

Turkey is in an active earthquake zone. Recently, Izmir city was shaken by a major earthquake in October 2020. The earthquake caused extensive structural damage and more than 100 casualties. Therefore, the analysis of the dynamic response of local soils in this region is of great importance. In this study, the shear modulus and damping ratio of natural silts obtained from Izmir province are determined. A total of 29 cyclic triaxial tests and 12 tests with pre-loading were performed to establish a general framework for understanding the behavior of local silt soils before and after an earthquake. Besides the effect of an earthquake, the characteristic behavior of Izmir silts of different levels of plasticity was also investigated and significant changes were observed. In addition, the effect of void ratio, effective confining pressure, plasticity, and shear stress amplitude of the pre-loading stage on the dynamic characteristics of the low plasticity silts were investigated. It is understood that after seismic action, changes in the small strain behavior of silts are remarkable.