Site Response Predictions at Atakoy Downhole Array

Year 2023, , 739 - 750, 27.09.2023

Yusuf Guzel , Fidan Güzel

https://doi.org/10.21205/deufmd.2023257517

Abstract

Site response analyses are seen to be the reliable way of reproducing and predicting earthquake input motions. The analyses are generally performed by adopting equivalent linear or nonlinear approaches solving the problem in time or frequency domains. Instrumented geotechnical downhole arrays, in this regard, are very important as to obtaining earthquake data through the soil deposits. This data can eventually be used to verify the approaches developed for site response analyses. In this study, the input motions of the 24.05.2014 (Aegean) earthquake event recorded at relatively recently installed Atakoy geotechnical downhole array are assessed. Moreover, the recorded input motions at the bottom bedrock level of the downhole array are simulated in the East-West and North-South directions. The site response analyses are conducted based on frequency domain equivalent linear approach. The peak ground acceleration and the spectral accelerations of the predicted input motions are compared with the recorded ones at 70 m, 50 m, 25 m and at the ground surface. The results indicate that the spectral acceleration predictions can be simulated well until the depth of 50 m. At 25 m and at ground surface, the predictions are always greater than the recorded one. However, the predictions still exhibits good indication of actual values in the North-South direction. In terms of peak ground acceleration and shear strain profiles, the predictions display the soil layers featured with different soil properties. The equivalent linear approach appears to be suited reasonably well in site response analysis.

Keywords

Site Response Analysis, Downhole Arrays, Earthquake Input Motions, Spectral Response Predictions

Ataköy Gözlem Kuyusunda Saha Tepki Tahminleri

Abstract

Saha davranış analizleri deprem ivme hareketlerini yeniden üretmede ve tahmin etmede kullanılabilecek bir yöntem olduğu benimsenmiştir. Saha analizleri, genellikle, problemi zaman veya frekans bazda çözen eşdeğer doğrusal veya doğrusal olmayan yaklaşımlar benimsenerek gerçekleştirilir. Enstrümanlı geoteknik gözlem kuyuları bu açıdan zemin tabakaları boyunca hareket eden deprem ivme değerlerinin elde edilmesi açısından oldukça önemlidir. Bu veriler nihayetinde saha davranış analizleri için geliştirilen yaklaşımları doğrulamak için kullanılabilir. Bu çalışmada, nispeten yakın zamanda kurulmuş Ataköy geoteknik kuyusunda kaydedilen 24.05.2014 (Ege) depreminin ivme hareketleri değerlendirilmiştir. Ayrıca, kuyuanakaya seviyesinde kaydedilen ivme hareketleri Doğu-Batı ve Kuzey-Güney yönünde simüle edilmiştir. Saha davranış analizleri, frekans bazlı eşdeğer doğrusal yaklaşıma dayalı olarak yürütülmüştür. Tahmin edilen ivme hareketlerinin maksimum yer ivmesi ve spektral ivmeleri, 70 m, 50 m, 25 m ve zemin yüzeyinde kaydedilen değerler ile karşılaştırılmıştır. Sonuçlar, spektral ivme tahminlerinin 50 m derinliğe kadar iyi bir şekilde simüle edildiğini göstermektedir. 25 m'de ve zemin yüzeyinde, tahmin edilen değerler kaydedilen değerlerden her zaman daha büyük olarak elde edilmektedir. Bununla birlikte, tahminler hala Kuzey-Güney yönündeki gerçek değerlere yakın olduğunu göstermektedir. Maksimum yer ivmesi ve birim şekil değiştirme profilleri açısından, tahminler farklı zemin özelliklerine sahip zemin tabakalarını yansıtmaktadır. Eşdeğer doğrusal yaklaşımın, saha davranış analizi için uygun bir yöntem olduğu görünmektedir.

Keywords

Saha Davranış Analizi, Geoteknik Gözlem Kuyuları, Deprem Zemin İvme Kayıtları, Spektral İvme Tahminleri

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