Construction Sequence of Subsea Tunnel.

Hi Xadlim

I recall the cross harbour tunnel that was built across the harbour in Hong Kong which was a cut and cover operation.

It was in relatively shallow water and was not too long which allowed the process.

A trench was dreged across the harbour and precast concrete boxes were lowered into the trench. The boxes were linked with tension cables. The joints between the boxes were gouted and the cables stressed to seal the entire tunnel. The trench was re filled to the original sea bed level and the water was pumped out.

You cannot do this in sections - it has to be the entire tunnel.

I hope that helps

Best regards

Mike Testro

Thanks for your valuable respond Mike.

Any great thoughts with the TBM method guys?

K/R

Hi Xadlim

The Tunnell Boring Method depends on two main factors:

1. Subsea conditions - it has to be impermeable.

2. Length of tunnel - it has to be long enough to be worth the deployment of a bespoke tunnel head.

Considering the English Channel tunnel it was bored through stiff clay and the 22 mile length allowed the economical deployment of two machines.

Best regards

Mike Testro

Thanks Mike, it gives me further ideas.