Seismic Analysis of Saturated Sand Deposits with Silt Layers

Liquefaction of saturated sands during earthquakes is known to be the cause of significant earthquake related damages, including loss of bearing capacity, lateral flow and spreading, slope failures. In recent earthquakes including the1999 Marmara Earthquake in Turkey, field observations have indicated that silt inclusions or silt layers in the sandy deposits can have significant effects on development of liquefaction. The objective of this work is to analytically study the behavior of saturated sand deposits with silt layers. For this purpose, a hypothetical soil profile in which silt layers exist has been selected. The selected profile was then modeled and analyzed using the LASS-IV code that has nonlinear effective stress analysis capability. As base motion, rock site recordings of the mentioned earthquakes were utilized. Furthermore, as part of this study, a parametric study has been conducted to further understand the effects of silt layers within sand deposits on the onset of liquefaction. The results of the analyses of various parameters such as depth of silt layer, the relative density of sand layer and maximum base acceleration were tabulated to summarize the effect of silt layers on the onset of liquefaction