Design Of Sprayed Concrete Lining In Soft Ground - A Uk Perspective

Sprayed concrete lined (SCL) tunnelling has seen rapid development over the last twenty years in the UK. The purpose of this paper is to give an update on the latest design philosophies and methodologies, and to discuss the future development trends for SCL tunnelling in soft ground. The paper will start with brief overview of past soft ground SCL tunnel design; especially the temporary sprayed concrete lining. After that, the paper will introduce the recent and most significant shift in design philosophy; the transition from temporary sprayed concrete lining to permanent sprayed concrete lining, with its implications for construction safety, cost and environmental impact. Some recent developments in the numerical modelling techniques to facilitate the design of the permanent sprayed concrete lining will be introduced. In conclusion, the paper will discuss the possible future trends of SCL tunnel design, in particular the "composite shell" lining, with its potential benefits for construction programme, cost and environmental impact, followed by additional thoughts on possible improvements in the numerical modelling of soft ground SCL tunnels.