The scope of works is comprises the design of a steel deck within the bottom of the GRECT shaft to support tunnelling activities during the various stages of the GRECT tunnel drive.
The pit bottom deck is formed of two primary sections as shown in Figure 1;
1. Steel invert frame installed on top of TBM cradle which is left in-situ following TBM launch (red). This frame has three phases of functionality;
a. Support gantries during TBM launch
b. Support single train track servicing TBM during initial launch
c. Support double train track
2. Modular steel structures either side of the TBM cradle forming a working platform at tunnel invert level in addition to an upper storage platform.
3. Temporary monorail to support cables during tunnel launch and gantry installation 4. Thrust restraint brackets for slurry feed and return pipes