Investigation of equivalent linear and non-linear site response analyses of micaceous sand layers

The aim of this study is to analyze linear and nonlinear site response of horizontally layered micaceous sand deposits. Micaceous soil deposits are found in certain parts of the world including Izmir, a highly populated city and located in a seismically active region in western part of Turkey. For the sites where liquefaction is not likely to occur, practitioners often use SHAKE, which is software is based on "equivalent linear approach", to determine the response of soils underlying the critical structures. However, it is well known that soils tend to show nonlinear behaviour even at small strains that may require a nonlinear analysis to better estimate the response of sites. NONLI3 which takes the nonlinear soil response into account has been also employed to investigate the effect of mica mixtures on the dynamic response of sites. The both site response analyses have been employed and site amplifications in terms of surface accelerations have been obtained under a real recorded earthquake excitation with a magnitude of Mw= 5.7 in the region. The results have been compared for various cases for two different analyses methods. The results present significant difference in surface accelerations between two methods. The effect of mica content on site response analysis has been noticed in the results.