ABSTRACT
Soil conditioning is a key factor for an effective, economical and safe construction of tunnels using EPB shield machines in closed mode. Depending on the geotechnical conditions there are different requirements regarding the soil conditioning process to be considered. Main goals among others are enhancements of face pressure control and soil flow/transport. The most frequently applied conditioning agent in EPB tunnelling is foam. Foam consists of time- and pressure dependent properties, which makes the design of the conditioning process challenging. In this publication, the authors will provide fundamental knowledge on the relevant foam properties for EPB tunnelling and methods of characterisation. Besides investigations on the time- and pressure dependent behaviour of foam, significant influences from the production process on the foam and approaches on the rheology of foam will be presented. Therefrom, indications will be given for soil conditioning in practice.
