Investigation of Displacements in Tunnel-Constructed Liquefiable Soils with Numerical Analysis

Year 2024, Volume: 24 Issue: 2, 374 - 387, 29.04.2024

İsa Vural , Dua Kayatürk , Ayşe Saçar

https://doi.org/10.35414/akufemubid.1325317

Abstract

The rise in industrialization and population has led to an increase in the economic significance of existing urban areas, and thus the utilization of underground space has become quite remarkable It is an undeniable fact that in seismically active regions, the underground areas are also exposed to the risk of earthquakes. The devastating 1995 Kobe-Japan, 1999 Chi-Chi-Taiwan and 1999 Kocaeli-Turkey earthquakes are known to have caused major damage to existing underground structures. In this study, numerical models based on finite differences in FLAC 2D were established to evaluate the displacements of the ground around the tunnels located in liquefiable soils. In order to represent the liquefaction condition in the models, soils in the Adapazarı region, which have alluvial characteristics, were used. Soil deformations were examined in models with varying tunnel depths and diameters, for both liquefiable and non-liquefiable soils within the same layers. As a result of this study, it is stated that more stability losses are observed in analyzes where liquefaction can be defined - that is, changes in pore water pressures can be modeled - compared to analyzes without liquefaction. The layout of the ground layers is important for the positioning of the tunnel. The placement of the tunnel towards the solid layers caused the deformations to decrease.

Keywords

Liquefiable soils, FLAC 2D, Tunnel, Adapazarı soils

Tünel İnşa Edilmiş Sıvılaşabilir Zeminlerdeki Yer Değiştirmelerin Sayısal Analizlerle İncelenmesi

Abstract

Sanayileşme ve nüfustaki artış, mevcut kentsel alanların ekonomik öneminin artmasına yol açmış ve böylece yeraltı alanlarının kullanımı oldukça dikkat çekici hale gelmiştir. Sismik açıdan aktif bölgelerde yeraltı alanlarının da deprem riskine maruz kaldığı yadsınamaz bir gerçektir. Yıkıcı 1995 Kobe-Japonya, 1999 Chi-Chi-Tayvan ve 1999 Kocaeli-Türkiye depremlerinin mevcut yeraltı yapılarında büyük hasara neden olduğu bilinmektedir. Bu çalışmada, sıvılaşabilir zeminlerde bulunan tünellerin etrafındaki zeminin yer değiştirmelerini değerlendirmek için FLAC 2D'de sonlu farklara dayalı sayısal modeller kurulmuştur. Modellerde sıvılaşma durumunu temsil etmek için Adapazarı bölgesindeki alüvyon karakterli zeminler kullanılmıştır. Zemin deformasyonları, aynı katmanlardaki hem sıvılaşan hem de sıvılaşmayan zeminler için değişen tünel derinlikleri ve çaplarına sahip modellerde incelenmiştir. Bu çalışma sonucunda, sıvılaşmanın tanımlanabildiği, yani boşluk suyu basınçlarındaki değişimlerin modellenebildiği analizlerde, sıvılaşma olmayan analizlere göre daha fazla stabilite kaybı gözlendiği belirtilmektedir. Zemin katmanlarının yerleşimi, tünelin konumlandırılması için önemlidir. Tünelin sağlam katmanlara doğru yerleşmesi deformasyonların azalmasına neden olmuştur.

Keywords

Sıvılaşabilir zeminler, FLAC 2D, Tünel, Adapazarı zeminleri

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