ABSTRACT
Frankfurt, one of the most densely populated capitals in Germany, needed an extension of its Metro Line U5 from the main railway station towards the newly created district ‘Europaviertel’ which is part of an urban rehabilitation plan affecting over 30.000 people.
For the first time in Frankfurt, TBMs were used for metro construction. Driving in full EPB mode at up to 3,2 bar in clay and sand/clay mixed face geology with sensitive surface construction as well as the connection to the existing tunnel system from the 1970s makes this project unique.
Apart from the 2k annulus grout – first time implemented in Germany for a city tunnel project, EPB startup with a prefilled working chamber has been used very successfully together with highly ecologic tail sealants and soil conditioning system with minimum impact on the excavated soil.
