Figure 2.
The image shows a three dimensional cutaway of a curved tunnel lining segment with an integrated fluid control and absorber system. The lining and tunnel form the outer curved structure. A flow header and a return header run horizontally across the tunnel interior, connected to a control valve near the centre. A pressure regulator valve is mounted on the lining wall. Below, an absorber pipe system with 25 millimetre diameter pipes is arranged in a serpentine pattern inside a support cage embedded in the lining. A transparent walkway spans across the tunnel interior above the pipes. Arrows indicate fluid flow directions through the system. Several dimensions are labelled, including 2650 millimetre widths, 1667 millimetre lengths, and an arc length of 883 millimetres, showing the spatial layout of components within the tunnel lining image.Schematic diagram of tunnel energy system showing embedded pipework and flow/return pipes in the tunnel (Nicholson et al., 2014a)