1D nonlinear site response analysis of the Isparta Basin (Southwestern Turkey) with surface wave (ReMi) and borehole data

Abstract

This study presents a soil-response analysis of Isparta basin, is situated in the one of most important tectonic areas, using surface wave (ReMi (TM)) and borehole data at 24 points. In the analysis, the nonlinear site response analysis approach was carried out using the DeepSoil software. The study area was characterized by C and D soil class according to NEHRP (National Earthquake Hazards Reduction Program) and TBEC-2018 (Turkish Building Earthquake Code-2018) soil classification criteria. For the modelling, the strong ground motion recordings of 6.9 Mw Irpinia and 6.4 Mw Dinar were used and the largest peak ground acceleration (PGA) and spectral acceleration (SA) maps of the study area were created. The Bdr-1914 model was made using Irpinia record, PGA values in the study area were determined in the range of 0.28-0.41 g and SA in the range of 0.77-1.82 g. In the Dnr-1995 model, the PGA values in the basin were found to be between 0.05-0.1 g and SA was within the range of 0.21-0.48 g. It was observed that the spectral accelerations on the surface, which significantly increased the effects of strong ground motion, particularly for Mw 6.9, near the city center and the Cunur area where new settlement areas were dense. The results indicate that ground specific design is required for construction in these areas, which are above the risk threshold in acceleration design spectra. At the same time, these results show the site response studies have critical importance and may make a significant contribution to the design of safe structures in the alluvial basins.