Structural properties and durability of a sprayed waterproofing membrane for tunnels

It is concluded that where sufficient bond is present, composite action arising from transfer of circumferential shear between the linings can be relied upon to improve performance in service for short-term and accidental situations. This allows for reduction of stiffness during the first few years. There is no evidence from tests lasting up to 2.2 years that significant further reduction would occur, but prediction of 100-year performance remains difficult.