ABSTRACT
Composite SCL tunnels, comprising two layers of permanent concrete linings and a sandwiched layer of sprayed waterproofing membrane, have been constructed in several major underground construction projects in the UK. The research on composite SCL tunnels has so far been focused on the performance of the permanent concrete lining when the sprayed waterproofing membrane is still bonded to both layers of linings. Recently, research has shifted towards the robustness of the sprayed waterproofing membrane system under external groundwater pressure and the impact of debonded sprayed waterproofing membrane on the concrete lining performance. This paper assesses the second issue by undertaking numerical modelling with various partially and fully debonded sprayed waterproofing membrane scenarios. The lining performance is presented and discussed. Further research on this topic is recommended.
