Micro Tunnelling Equipment
Our investment in the Herrenknecht AVN Slurry based Microtunnelling equipment in 2008 has resulted in the completion of 25 individual tunnels. This in-house ability to drive 1200mm, 900mm and 600mm tunnels up to 250m in all soil types from 250MPa rock to 0.0 N value silt with our own home-grown crew has given great flexibility when working in urban areas especially where underground services are present. The associated slurry separation system consisting of vibrating screens and hydro-cyclones allows the removal of suspended solids down to 50 microns with Centrifuge equipment working below this level down to 0.0 microns. All of these tunnels are driven from shafts which can be precast in our yard. 600dia can be launched from a 3.2m id shaft and the 900 and 1200 from a 5m id. Drive lengths are typically 100m for the 600 with 500m possible for the 1200 using inter-jacks. The management of this system relies on a good working knowledge of ground conditions.
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