Site investigation beyond the face of a gallery using frequential seismic survey

摘要

The Papillon Gallery is a ventilation gallery linking the two tubes of the EOLE project under Paris. Disturbed material was encountered during the excavation, and it has been decided to perform investigations to determine the extent of the altered zone. The frequential seismic survey analyses the spectral content of a wave travelling inside the studied medium. The high frequency waves do not travel in an altered medium. This method uses the cross-hole technique. In the case of the Papillon Gallery, this technique has given a very good prediction.