Canopy/umbrella tubes (with diameters of typically 76-168mm but occasionally larger) are a support system used in conventional and mechanical tunnel construction in poor soil conditions.
The drill rig and drill mast are positioned and drilling executed (often using the symetrix method) with lost casing. Grouting with packer and cement grout is then used if specified.
The steel tubes are sourced from reputable providers and material certificates are tracked within our inspection and testing plans. Previously we have performed pre-construction testing to demonstrate lateral capacities are achieved across the tube joints.
Grout mixes are based on our long experience and are typically tested based on our standard procedures.