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San Francisco HEP Headrace Tunnel – TBM Success under the Presence of Pressurized Water in Faulty Deep Rock
Author(s) -
de Oliveira Filho Afranio Alves,
Belitardo Gustavo Teixeira,
Büchi Ernst,
Vigl Alois
Publication year - 2008
Publication title -
geomechanik und tunnelbau
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.317
H-Index - 18
eISSN - 1865-7389
pISSN - 1865-7362
DOI - 10.1002/geot.200800063
Subject(s) - hydropower , excavation , hydroelectricity , shield , mining engineering , environmental science , geology , geotechnical engineering , engineering , petrology , electrical engineering
The San Francisco Hydroelectric Project in Ecuador is utilizing hydropower from the Rio Pastaza in a 230 MW plant. 8.4 km of the 11.2 km long HRT have been excavated by a double shield (DS) TBM. After 4,950 m TBM excavation in metamorphic rock series of the Cordillera Real, the TBM was trapped by a block failure of the rock under high water ingress and the TBM shield was demolished. A rescue programme was undertaken immediately on the TBM in order to stabilize the region of the event, to get control about the water ingress, to make free and to repair the TBM and to continue excavation under controlled conditions. Concurrently an alternative rescue programme was investigated and started in order not to waste time if the rescue of the TBM should fail or if further events should occur. The TBM stoppage lasted for about five month and the rescue programme enabled the repair of the TBM and a controlled restart of the TBM without any accident. After the restart the TBM again reached a sufficient daily progress of more than 20 m/d and the tunnel could be finalized with success.