Alüvyon Zeminlerin Sıvılaşma Potansiyelinin Sayısal Analiz ile Belirlenmesi ve Zemin İyileştirmesinin Analize Etkileri

Yıl 2024, Cilt: 27 Sayı: 3, 1029 - 1041, 25.07.2024

Selen Davran , Aşkın Özocak , Sedat Sert , Ertan Bol

https://doi.org/10.2339/politeknik.1105277

Öz

Depremler sırasında yumuşak alüvyon zeminlerin bulunduğu bölgelerde sıvılaşma kaynaklı hasarlar meydana gelebilmektedir. Bu nedenle bu çalışma, alüvyon kökenli Adapazarı zeminlerini temsil eden tipik bir kesitin sıvılaşma potansiyelinin sayısal analiz yardımıyla değerlendirilmesini konu almaktadır. Analizler, Plaxis 2D yazılımı ile yürütülmüş, zemin kesiti ise UBCSAND malzeme modeli ile modellenmiştir. Ek olarak, sıvılaşma potansiyeli yüksek olan Adapazarı zemin kesitinde, zemin iyileştirmesinin sıvılaşmaya karşı etkisinin belirlenebilmesi adına, yapı yükü uygulanması halinde ve yapı altında jet-grout kolonlarının modellenmesi durumlarında analizler tekrar edilmiştir. Deprem verisi olarak 1999 Marmara Depremi kullanılmıştır. Yapılan analizler sonucunda belirli analiz noktaları seçilerek, bu noktalardaki ivme-zaman, deplasman-zaman ve boşluk suyu basıncı değişimleri incelenmiştir. Söz konusu analiz noktalarında maksimum ivme değerleri incelendiğinde, bazı noktalarda sıvılaşmanın sönümlenememesi ile zemin büyütmelerinin yaşandığı gözlemlenmiştir. Deplasman-zaman değişimlerinde ise iyileştirmenin yatay deplasmanları %59 değerine kadar azalttığı belirlenmiştir. Ek olarak, iyileştirmenin olmadığı durumda boşluk suyu basınçlarının toplam gerilmeye ulaştığı ve sıvılaşmanın gerçekleştiği; iyileştirme durumunda ise boşluk suyu basınçları toplam gerilmeye ulaşmadığından sıvılaşmanın önüne geçildiği gözlemlenmiştir. Sonuçlara dayanarak, modelin sıvılaşma davranışını temsil edip etmediğinin daha detaylı tartışılması gerektiği belirlenmiştir.

Anahtar Kelimeler

Jet-grout, sıvılaşma potansiyeli, UBCSAND modeli, zemin iyileştirme

Evaluation of Liquefaction Potential on Alluvial Soils by Numerical Analysis and Effect of Soil Improvement on the Analysis

Öz

During earthquakes, liquefaction-induced damages may occur in areas with soft alluvial soils. Therefore, this study deals with the evaluation of the liquefaction potential of a typical section representing the alluvial origin Adapazarı soils with the help of numerical analysis. The analyzes were carried out with Plaxis 2D software, and the soil section was modeled with the UBCSAND material model. In addition, in Adapazarı soil section with high liquefaction potential, the analyzes were repeated in order to determine the effect of soil improvement against liquefaction, in case of application of structural load and modeling of jet-grout columns under the structure. 1999 Marmara Earthquake was used as earthquake data. As a result of the analysis, certain analysis points were selected and the acceleration-time, displacement-time and pore water pressure changes at these points were examined. When the maximum acceleration values were examined at the mentioned analysis points, it was observed that there are soil amplifications due to the undamped liquefaction. In case of the displacement-time changes were examined, it was determined that the improvement reduced the horizontal displacements up to 59%. In addition, in the absence of improvement, pore water pressures reach total stress and liquefaction occurs; in the case of improvement, it was observed that liquefaction was prevented since the pore water pressures did not reach the total stress. Based on the results, it was determined that whether the model represents liquefaction behavior should be discussed in more detail.

Anahtar Kelimeler

Jet-grout, liquefaction potential, UBCSAND model, soil improvement

Kaynakça

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