6 Şubat 2023 Kahramanmaraş-Pazarcık (Mw=7.7) ve Elbistan (Mw=7.6) Depremleri 11 ilimizi etkilemiş olup depremler, Türkiye'nin doğusunda ve güney doğusunda yer alan Hatay, Adıyaman, Kahramanmaraş, Malatya, Gaziantep, Osmaniye, Adana, Kilis, Diyarbakır, Şanlıurfa ve Elazığ illerinde binlerce insanımızın hayatlarını kaybetmesine, on binlerce insanın yaralanmasına, alt yapı ve ulaşım sistemlerinde, yapılarda ve yollarda ciddi hasarlara neden olmuştur. Bu çalışma kapsamında 6 Şubat depremleri sonrasında sahaya özel analizlerle, hasarın ve yıkımın ne kadar büyük olduğunu tahmin edebilme kapasitesi araştırılmıştır. Her türlü statik-sismik tasarım için yönetmelik genel bir standart sunmaktadır. Depremlerin yıkıcılığının azaltılmasına bir katkı sağlamak amacıyla bölgede depremden en çok etkilenen 3 farklı bölgeden alınan sondaj-sismik ölçüm bilgilerine dayanarak sahaya özel analizler yapılmıştır. Arazi ve laboratuvar deney sonuçlarından yararlanılarak DeepSoil v6 programında zemin büyütme ve sıvılaşma analizleri yapılmıştır.

Shear wave velocity (V_s) is an important characteristic in geotechnical earthquake engineering practices for estimating site response. Seismic refraction and well seismicity are the common ways to determine the shear wave velocity. However, these methods require on-site land studies. For this reason, there are empirical approaches that have been proposed to calculate V_s depending on the number of SPT-N obtained from the Standard Penetration experiment data. Studies in the literature have different aspects and correspond to varied empirical approaches. The study aims to establish empirical correlations between the Shear Wave Velocity (V_s), Standard Penetration Test results (SPT-N), and stress conditions of soils considering the soil types of the local sites in Eskişehir, Turkey. The V_s values of the soil from the data set we used in this study were obtained from seismic refraction-reflection studies in 22 different locations in Eskişehir. SPT-N values obtained from 42 boreholes representing the Eskişehir ground were used. The Vs values calculated from the empirical approaches given depending on the SPT-N values and the V_s values measured on the site were compared. In addition, regression analyses were performed between SPT- N and V_s. As a result of the regression analyses performed, new empirical correlations were developed according to soil types. Finally, new empirical correlations are established that can predict V_s at different soil depths and conditions taking the soil type and overburden pressure into account and contributing valuable insights for geotechnical earthquake engineering purpose. The regressions show that there is a good correlation between the V_s-SPT-N along with the total stress with high R²s and soil types are effective on predicting the shear wave velocity.

Recent studies about liquefaction initiation are widely encountered in the literature in terms of utilizing the dynamic triaxial tests under harmonic loading and site response of liquefied zones. Sandy-like or clayey-like behavior is important for estimating the liquefaction susceptibility but there are other factors related to cyclic loading characteristics such as frequency content and stress level. Besides, 1-D ground response analyses are employed to understand the behavioral transmission through the soil column in liquefiable areas. The study here focuses on two main aspects of the liquefaction. The first part consists of the estimating of the pore pressure generation under irregular excitations, whereas the second part aims to assess the efficiency of the building codes predicting the nonlinear site response in liquefied prone areas. The laboratory results show that the frequency content has big influence on the liquefaction at varying stress levels. Moreover, literature models have discrepancies to estimate the pore pressure generation under different types of loading. Regarding the site response, it was indicated that equivalent linear approach is incapable of predicting the seismic behavior of soil column; therefore, nonlinear ground response must be run instead, and the IBC is the most effective one to match the nonlinear analysis results.

The behavior of the soils under dynamic loads is of great importance for the structures to be built in earthquake zones. As a result of the determination of the site-specific dynamic parameters of the soils and the analyzes to be made with these parameters, the ground response that will occur on the surface during the earthquake will be determined. Turkey is located in one of the important earthquake belts of Europe. Studies are carried out on the North Anatolian Fault Zone (NAFZ), which is one of the important and active fault lines here. In this study, as a result of 4 drilling studies on NAFZ, firstly, dynamic triaxial (TRX) and resonant column (RC) test systems were used to obtain site-specific shear modulus and damping curves depending on depth. 11 earthquake acceleration records reflecting the seismic characteristics of the region were selected and scaled in both time-history and frequency-time domains. Two different scaling methods were compared with the nonlinear soil amplification analysis. In addition, surface response spectra were examined according to the Turkish Building Earthquake Code (TEC 2018). Although there is not a big difference in amplification values in two different scaling methods, it has been determined that the design spectrum values are very different.

In the earthquakes that occurred in the Pazarcık (Mw = 7.7) and Elbistan (Mw = 7.6) districts of Kahramanmaraş Province on 6 February 2023, many buildings collapsed in the Hayrullah neighborhood of the Onikişubat district. In this study, we investigated whether there was a soil amplification effect on the damage occurring in the Hayrullah neighborhood of the Onikişubat district of Kahramanmaraş Province. Firstly, borehole, SPT, MASW (multi-channel surface wave analysis), microtremor, electrical resistivity tomography (ERT), and vertical electrical sounding (VES) tests were carried out in the field to determine the engineering properties and behavior of soil. Laboratory tests were also conducted using samples obtained from bore holes and field tests. Then, an idealized soil profile was created using the laboratory and field test results, and site dynamic soil behavior analyses were performed on the extracted profile. According to The Turkish Building Code (TBC 2018), the earthquake level DD-2 design spectra of the project site were determined and the average design spectrum was created. Considering the seismicity of the project site and TBC (2018) criteria (according to site-specific faulting, distance, and average shear wave velocity), 11 earthquake ground motion sets were selected and harmonized with DD-2 spectra in short, medium, and long periods. Using scaled motions, the soil profile was excited with 22 different earthquake scenarios and the results were obtained for the equivalent and non-linear models. The analysis showed that the soft soil conditions in the area amplified ground shaking by up to 2.8 times, especially for longer periods (1.0–2.5 s). This level of amplification was consistent with the damage observed in mid- to high-rise buildings, highlighting the important role of local site effects in the structural losses seen during the Kahramanmaraş earthquakes.