Herrenknecht News Release
Back up systems enabled two-ring construction sequence
- Breakthrough under the Pyrenees is achieved after the second of two 4.3m diameter Herrenknecht hard rock TBMs drove into the tunnel excavated under the mountains by its sister machine a month earlier.
- Completion of the concluding leg of the two-heading assault marks successful excavation of the 8.2km-long segmentally-lined tunnel that forms the centrepiece of a 64.5km-long high voltage electricity transmission link between France and Spain. The tunnel is part of the INELFE Pyrenees bi-national project (INterconexión ELéctrica Francia-España) that links Baixas, near Perpignan in France, to Santa Llogaia, near Figueras in Spain.
- Herrenknecht double shield TBMs Canigou and TBM Alberas launched from separate portals last year (2012); TBM Alberas from La Jonquera on the Spanish side on a longer 7km heading in March, and TBM Canigou for a 1.23km heading from Montesquieu-des-Albéres in France in October.
TBM Canigou, one of two 4.3m diameter machines on the INELFE project
- The machines were both ordered by the Franco-Spanish joint venture, consisting of tunnelling specialists Eiffage and Dragados. Two machines were necessary to meet the demanding timeframe set by Réseau de Transport d'Electricité (RTE) and Red Eléctrica de España (REE).
- TBM Canigou reached the end of its journey, underneath the Massif des Albères, in March (2013). The machine was immediately dismantled in a tunnel section in stable rock without any lining under the supervision Herrenknecht specialists. The specially-designed machines were manufactured in such a way as to enable them to be dismantled within the confines of the tunnel diameter without the need to break out an additional cavern. TBM Alberas drove into the tunnel excavated by its sister machine on April 22 (2013).
8.2km tunnel forms centrepiece of France-Spain cable link
- Best performance on the overall project was achieved by TBM Alberas on the Spanish side: a best of 53.5m in a single day with a best monthly performance of 1,040m completed tunnel per month. TBM Alberas was also dismantled inside tunnel, with components removed through the north portal.
- Cross-border electricity lines that connect Spain with France and the rest of Europe need to be extended urgently because the four existing connections do not have sufficient capacity to cope with peak demand or to compensate for fluctuations resulting from the use of renewable energy sources.
- For the INELFE project Herrenknecht prepared the back-up systems of the two machines for double storage: logistics and storage facilities were designed in such a way that segments and grout could always be stored on the machine for a two-ring building sequence. TBM operators were therefore able to exploit the potential of the double shield principle, without being limited by possible shortages in the material logistics.
- The INELFE tunnel runs broadly parallel to the 16.4km-long Le Perthus railway tunnel, built by Eiffage TP and Dragados between 2005 to 2007 using two 9.9m diameter double shield TBMs.
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