Subsea Tunneling Design and Reinforcement MethodsCarlos Jimenez

1. Noteworthy Tunnels2. Pregrouting3. Analysis Methodology4. Tunnel Linings5. Alternative Subsea Tunnels6. TBM’s for Subsea Tunneling

Noteworthy Subsea Tunnels around the world

● Atlantic Ocean Tunnel - Norway

● BART Transbay Tube - San Francisco Bay Area

● Channel Tunnel - Interconnecting France and England

● Seikan Tunnel - Japan

● Xiamen Xiang'an Tunnel - China

Atlantic Tunnel - Norway

Channel and BART Tunnels

Xiamen-Xianan & Seikan Tunnels

Xiamen-Xiangan tunnel

Seikan Tunnel

Pregrouting

● Grout is injected into rock ahead of the tunnel face to seal fissures in rock

● Bores are at an angle heading away from the tunnel face.

● End up with a “grout zone”

● Decreases possibility of water intrusion from occurring

Pregrouting

Pregrouting

Pregrouting

● Inverse relationship between grouting radius and seepage volume.

● Direct relationship between seepage volume and tunnel radius

Analysis

Analysis

● Huge quantity of overlying water pressure on tunnel

● Rock pressure acting on tunnel as well

Analysis

Norwegian findings for optimal rock cover

Tunnel Linings

● Material must be impermeable

● Usually reinforced concrete, shotcrete or precast concrete panels.

● Anchor bolts and rods used to secure walls.

● Waterproof liner to prevent water damage to tunnel

Tunnel Linings

Channel Tunnel lining

Trans-Tokyo Bay Highway

Tunnel Linings

● Channel tunnel consists of precast panels● Trans-Tokyo tunnel is a shield tunnel

Atlantic Tunnel Project

Tunnel Linings

● Atlantic tunnel suffered a cave in and huge amounts of water intrusion

● Required thousands of grout to seal

● Combination of shotcrete and anchors and rebar line the tunnel’s walls

Alternative Subsea Tunnels

Alternative Subsea Tunnels

● “Tunnel” is a steel tube in an underwater trench along seabed

● BART is located in hot seismic zone

● Majority of seabed in bay area is composed of alluvium or bay mud.

TBM’s for Subsea Tunneling

● Difficult for modern day TBM’s to pass through variety of materials

● Cannot travel long distances

● Not built to withstand large pressures on them

● Ongoing design of TBM’s with sole purpose of excavating subsea tunnels

TBM’s for Subsea Tunneling

Thank you.

Sources

“The Channel Tunnel.” Dw, 24 Aug. 2015.

C.J. Kirkland, “The proposed design of the English Channel Tunnel”, Tunnelling and Underground Space Technology, Volume 1, Issues 3–4, 1986, Pages 271-282

Dunn, James, et al. "Raising the Bar on BART." Civil Engineering, vol. 71, no. 12, 2001, pp. 60-65.

Keinosuke Uchida, Yujirou Wasa, Makoto Kanai, “Design of the shield tunnel for the trans-Tokyo bay highway”, Tunnelling and Underground Space Technology, Volume 7, Issue 3, 1992, Pages 251-261

Kitamura, Akira, and Yuzo Takeuchi. "Seikan Tunnel." Journal of Construction Engineering and Management 109.1 (1983): 25-38.

Li, Pf., Zhou, Xj. “Mechanical behavior and shape optimization of lining structure for subsea tunnel excavated in weathered slot.” China Ocean Eng 29, 875–890 (2015).

Nilsen, Bjorn. "Main challenges for deep subsea tunnels based on norwegian experience." Journal of Korean Tunnelling and Underground Space Association 17.5 (2015): 563-573.

Swan, Rachel. “Transbay Tube.” SF Chronicle, 9 Feb. 2019

Wallis, Shani. “5.7km Long Route of Norway's 28th Undersea Road Tunnel since the First Was Completed in Vardø in 1981.” Tunnel Talk, Dec. 2009.