Determination of local site soil conditions by microtremor measurements for sustainable buildings

Abstract

As well known, local soil condition at a specific site affects the significant features of strong ground motion such as amplitude, frequency range and time duration. The effects of site condition depend on the properties of the motion characteristics, material properties, topography and geometry of the field. The bedrock slope at the basin sides also is one of the most important factors in the response analyzing of a specific site in geotechnical earthquake engineering applications. The reflection and refraction waves from the basin edges induce the wave transmission and two dimensional effects. In this case two dimensional site response analyses are required to estimate the behavior of the soil layers. So, local geotechnical site condition should be into account in the design of earthquake resistant building. The bedrock slope of the basin edges should be determined for suitable method in two dimensional dynamic response analyses. In this study, the result of a specific site response based on shear wave velocity profiles determined by microtremor array measurements are presented. The geotechnical properties of the soil layers were obtained from the previous subsurface explorations. Seismic bedrock depth and bedrock slope of the edge were defined by microtremor array measurements. Shear wave velocity value is from ten to hundred meters was obtained from passive surface wave method by employed Spatial Auto Correlation algorithm. Established variation of shear wave velocity with depth models were examined in terms of local site amplification. In order to verify consistency of obtained amplification numbers, empirical and measuremental results were compared for each site. As a conclusion, dynamic properties of local site conditions under earthquake excitation were described in terms of maximum amplification, resonance frequency and predominant period.