Full face excavation in difficult ground

This paper describes the evolution of full face excavation from the mid 1980s to the present. During this time, more than 1,000 km of tunnels have been designed, excavated and completed using full face excavation, with cross sections ranging in size from 120 to 220 m2, in different geological and geotechnical conditions, near the ground surface or at depth.
Starting from the basic concepts of the approach (ADECO-RS) applied at the tunnel design stage and during construction, the experience gained and the lessons learned are summarised. It is shown how full face excavation has been developed and improved through the experience gained from the construction of both road and railway tunnels in the past thirty years.
In order to highlight the current stage of development, with new materials, technologies, modelling methods and increased capacity in observation and real-time monitoring of tunnel behaviour becoming available, the case of the Sochi Tunnel in Russia is presented and a comparison with the New Austrian Tunnelling Method (NATM) is illustrated.