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

References

• Allen C.R. 1982. Comparison between the North Anatolian fault of Turkey and the San Andreas fault of California. In: Isikara A.M. and Vogel A. (eds), Multidisciplinary Approach to Earthquake prediction. Proceedings of the International Symposium on Earthquake Prediction in the North Anatolian Fault Zone held in Istanbul, March 31–April 5, 1980. Vol. II. Vieweg, Braunschweig, 67–75.
• ASTM International, 2006. Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System). ASTM D2487-06. ASTM International, WestConshohocken, PA.
• Azadi M., Hosseini S. M. M. M., 2010. Analyses of the Effect of Seismic Behavior of Shallow Tunnels in Liquefiable Grounds, Tunnelling and Underground Space Technology, 25, 543-552.
• Beaty M. H. and Perlea V. G., 2011. Several Observations on Advanced Analyses with Liquefiable Materials. 31th Annual USSD Conference, U. S. Society on Dams, San Diego, California. 1369-1397.
• Byrne, P. M. 1991. A Cyclic Shear-Volume Coupling and Pore-Pressure Model for Sand, Second International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, Missouri, March. Paper No. 1.24, 47-55.
• Cetin, K. O., Armen Der Kiureghian, and Raymond B. Seed. 2002. Probabilistic Models for the Initiation of Seismic Soil Liquefaction. Structural Safety 24 (1): 67–82. https://doi.org/10.1016/S0167-4730(02)00036-X.
• FLAC 2D, User’s Manual-Fast Lagrangian Analysis of Continua, Itasca Consulting Group, Minnesota.
• Hashash Y.M.A., Hook J.J., Schmidt B., Yao J.I., 2001. Seismic Design and Analysis of Underground Structures, Tunnelling and Underground Space Technology, 16, 247-293.
• Huang, Y., Yu, M. 2013. Review of soil liquefaction characteristics during major earthquakes of the twenty-first century. Nat Hazards 65, 2375–2384 (2013). https://doi.org/10.1007/s11069-012-0433-9
• Iida H., Hiroto T., Yoshida N., Iwafuji, 1996. Damage to Daikai subway Soils and Foundations, Special Issue on Geotechnical Aspects of Hyogoken-Naambu Earthquake, Japanese Geotechnical Society, 36, 280-300..
• Kutanis M., Arman H., Fırat S., Gündüz Z., 2002. 17 Ağustos 1999 Marmara Depremi ve Adapazarı Bölgesinde Gözlemlenen Deprem Hasarları, IV. Mühendislik ve Mimarlık Sempozyumu, Balıkesir, 459-460..
• Mahmoud, A. O., Hussien, M. N., Karray, M., Chekired, M., Bessette, C., & Jinga, L., 2020. Mitigation of liquefaction-induced uplift of underground structures. Computers and Geotechnics, 125, 103663.
• Ueng T.S., Lin M.L., Chen M.H., 2001. Some geotechnical aspects of 1999 Chi-Chi, Taiwan earthquake, Proceeding of the Fourth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, SPL-10, 1-5.
• Unutmaz B., 2014. 3D Liquefaction Assessment of Soils Surrounding Circular Tunnels, Tunnelling and Underground Space Technology, 40, 85-94.
• Vural İ., 2012., Alüvyal ve Sıvılaşabilen Zeminlerde Altyapıların Deprem Risk Analizi: Adapazarı Örneği, (Doktora tezi), Sakarya Üniversitesi, Fen Bilimleri Enstitüsü, 160.
• Wang, T. T., Kwok, O. L. A., & Jeng, F. S., 2021. Seismic response of tunnels revealed in two decades following the 1999 Chi-Chi earthquake (Mw 7.6) in Taiwan: A review. Engineering Geology, 287, 106090.
• Wang, Z. Z., and Z. Zhang. 2013. Seismic Damage Classification and Risk Assessment of Mountain Tunnels with a Validation for the 2008 Wenchuan Earthquake. Soil Dynamics and Earthquake Engineering 45: 45–55. https://doi.org/10.1016/J.SOILDYN.2012.11.002.
• Zhuang, H., Hu, Z., Wang, X., & Chen, G., 2015. Seismic responses of a large underground structure in liquefied soils by FEM numerical modelling. Bulletin of Earthquake Engineering, 13, 3645-3668.