Presentation1 different methods of tunnel.pptx

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1. 4. Immersed Tunnels Immersed tunnels are prefabricated tunnel sections placed underwater, typically used to cross shallow bodies of water ( Kuesel et al., 2012). They provide a transportation link in areas where bored tunnels or bridges may be impractical. Figure: Image of an immersed tunnel.

2. Types of immersed tunnel 1. S inge-shell steel tunnel 2. Double-shell steel tunnel 3. Sandwich construction tunnel 4. Concrete-Immersed tunnels S ource: Sciencedirect.com

3. Construction Method Trench Excavation : The first step involves excavating a trench along the path where the tunnel will be placed. This trench is typically dug in the seabed, using specialized dredging equipment (Clamshell dredgers). Foundation Preparation : The trench needs a stable base to support the heavy tunnel elements and prevent settlement after installation. Using sand injection or grout injections to stabilize the base (Zhou et al., 2021). Fabrication of Tunnel Elements : The tunnel sections are typically prefabricated at a dry dock or shipyard, far from the installation site. Clamshell Dredgers Installation of a continuous rubber gasket Sand injection

4. Construction Method Transportation & Lowering : Once the tunnel sections are constructed, they are floated to the installation site using pontoons or tugboats. Alignment & Connection : Once a tunnel section is in place, it must be aligned with the previous section with a high degree of precision. Misalignment can lead to leaks or structural problems later on. Backfilling : Backfilling is done to secure the tunnel sections in place and provide additional support and protection from external forces such as water currents or earthquakes. Tunnel elements in transportation.

5. Advantages Immersed tunnels can be designed to accommodate a wide range of cross-sections, allowing for versatility in their use. Immersed tunnels can support larger cross-sections than bored tunnels, which is crucial for busy transportation corridors. As long as the seabed is reasonably stable, these tunnels can be constructed with minimal disruption, making them suitable for coastal and river crossings in a variety of geological settings. Limitations During the transportation and placement of tunnel sections, marine traffic is often disrupted. It is sensitive to Ground Conditions. The trench must be stable enough to support the tunnel sections without shifting or collapsing. Location Challenges

6. Real life Examples Oresund Tunnel (Denmark-Sweden) Part of the Øresund bridge and tunnel connection, crossing shallow water (Hedberg, 2002). which connects Denmark and Sweden via both a bridge and a tunnel. Hong Kong-Zhuhai-Macau Bridge Tunnel One of the longest undersea tunnels in the world ( Quanke et al., 2022). This tunnel is part of the Hong Kong-Zhuhai-Macau Bridge, a massive infrastructure project that connects Hong Kong, Macau, and Zhuhai. Busan- Geoje Fixed Link (South Korea) Connects Busan to Geoje Island with an immersed tunnel section. connects Busan, South Korea’s second-largest city, to the island of  Geoje . Oresund Tunnel Hong Kong-Zhuhai-Macau Bridge Tunnel Source: Sciencedirect Source: Sciencedirect Busan- Geoje Fixed Link S ource: Engineering new records

7. Hedberg, T. (2002). Øresund Fixed Link, Denmark and Sweden.  Structural Engineering International ,  12 (4), 239–241. https:// doi.org /10.2749/101686602777965171 Kuesel , T. R., King, E. H., & Bickel, J. O. (2012).  Tunnel Engineering Handbook . Springer Science & Business Media. Quanke , S., Yongling , Z., Yue, C., Lei, F., Yu, Y., Zongxian , S., de Wit, H., & Ying, L. (2022). Hong Kong Zhuhai Macao Bridge-Tunnel project immersed tunnel and artificial islands – From an Owners’ perspective.  Tunnelling and Underground Space Technology ,  121 , 104308. https:// doi.org /10.1016/j.tust.2021.104308 Zhou, M., Su , X., Chen, Y., & An, L. (2021). New Technologies and Challenges in the Construction of the Immersed Tube Tunnel of the Hong Kong-Zhuhai-Macao Link.  Structural Engineering International , 1–10. https:// doi.org /10.1080/10168664.2021.1904487