The 570 m long Tarifa Experimental Gallery has allowed the investigation of three of the five flysch units involved in the future tunnel of Gibraltar. This Tunnel will have a length of 38 km approximately and will cross the Strait. For this reason, the results obtained from in situ testing, instrumentation measurements and laboratory tests are presented.
The Tarifa Experimental Gallery is a major geotechnical experiment carried out within the ongoing process of studies by the Spanish SECEG (Sociedad Española para la Comunicación Fija del Estrecho de Gibraltar) and by the Moroccan SNED (Societe Nationale d'Etudes du Detroit) into the feasibility of a tunnel across the Strait of Gibraltar. In Figure 1 are shown the location of the future tunnel as well as the location of the gallery. Thus, it can be roughly summarised that the picture we have of the geological environment of the tunnel route is a massive, highly impervious clayish formation, sometimes armoured–sometimes not- with hard slabs, mostly of sandstone, unpredictably oriented. This particular situation led us to investigate the geotechnical behaviour of the terrains involved in the project by relatively large experimental works located on both shores of the strait at representative sites. To this end, the 300 m-deep Malabata Shaft (Jan. 94-Dec. 95) was sunk in the Moroccan shore and the 75m-deep Bolonia Shaft (Jul.93-Oct.93) as well as the 570mlong Tarifa Gallery (Feb.95-Aug.95) have been built in the Spanish shore of the strait. All of them are now completed in that sense that the civil work and auscultation during construction is finished and that different instrumentation programmes of significant duration have already been carried out: however, further different observations and complementary testing are under way or expected to start in the future.
