Width of the slope protection crest and toe berm was reduced Slope of the berm was also reduced
Armor Stones of 15-30 ton 100yr return period waves of Hs=12.50’
The CBBT Parallel Thimble Shoal Tunnel Project will construct a new twolane tunnel under Thimble Shoal Channel. When complete, the new tunnel will carry two lanes of traffic southbound and the existing tunnel will carry two lanes of traffic northbound.
As part of the CTJV Project and included within the temporary works needed on Portal Island 1, Chesapeake Tunnel Joint Venture (CTJV) asked AZIERTA for a peer review of the design for the Portal Island Berms.
The project consisted in the review of the MetOcean information, wave calculations, berms slope stability analyses, sheet pile design and buoyancy calculation of the tunnel.
Azierta came up with a revised berm profile more efficient and economic. Also, the impact of a 5-year storm event was studied in order to evaluate the risk of its occurrence in mid construction (without the protection of the armor stone). The trestles adjacent to the island were also studied and checked for the conditions aforementioned
