Design and construction of two parallel pipe jacked tunnels, one 120m long and the other 54m, passing under two drains and a river. Abergeldie’s EPBM machine was used to bore the tunnels and jack into place segments of hydrostatic lining sleeve.
Boring under sensitive waterways permitted zero subsidence of overlying soils, which varied greatly in consistency over quite short distances. Very tight alignment tolerances were specified, allowing only 50mm vertical variation and 100 mm horizontal. Actual alignment accuracy achieved was within <50mm.
Thiess Degremont Nacap Pipeline JV