TBM SHIELD CRADLE AND THRUST FRAME

Hampton Roads Bridge-Tunnel Expansion (HRBT)

SUMMARY

Thrust Frame:

Thrust frame made of box sections of different dimensions but same thickness: 2” (except the vertical legs and the struts, where the thickness is 2 ½”).

Stiffeners will be used within the sections, which have different dimensions but same thickness: 1 ½”.

Shield Cradle:

Concrete elements to be precast blocks or in situ, Steel members for the rail supports: W 14x193

Steel members for the cradle structure: HP 12x89, Steel members for the lateral supports: W 8x35

Spreader Beam:

2’ 6” x 34’ 1-¼” x 2” top steel flange for the spreader beam. 3’ 8” x 34’ 1-¼” x 2” bottom steel flange for the spreader 2’ 2” x 28’ 10-¾” x 2” web for the spreader beam

The I-64 Roads Bridge-Tunnel in southeastern Virginia, between the cities of Hampton and Norfolk, has long been one of the most congested corridors of the region. The existing 3.5-mile facility consists of two, 2-lane immersed tube tunnels on artificial islands with trestle bridges to shore. These tunnels opened in 1957 (current westbound lanes) and 1976 (eastbound lanes) and are approximately 7,500 feet long.

The Hampton Roads Bridge-Tunnel (HRBT) Expansion Project will ease this congestion by widening the 4-lane segments of the I-64 corridor in the cities of Hampton and Norfolk.

As part of the HRBT Expansion Project and included within the temporary works needed on the South Island, Hampton Roads Connector Partners (HRPC) asked AZIERTA for a design of the TBM shield cradle and thrust frame. These structures are needed to support the TBM before and during the launching operation.

With respect to the actions, both the self-weight of the structure and the horizontal load due to the thrust of the EPB have been considered. Regarding the thrust of the EPB, the total load provided was 50.000 kN (22.240 kip).