Tunnel wall insulation - using foam plastics-filled sheaths which are later emptied to provide drainage channels

摘要

Tunnel walls are insulated by applying to the bare rock over the whole or parts of the tunnel wall one or more sheaths of polyethylene or PVC, which are nailed to the rock, filling the sheaths with expanded polystyrene granules to form one or more beads, covering the wall with insulation such as a plastics film, and finally applying concrete, The granules are later dissolved and removed to leave drainage channels.