2m 3/m and this consumed 67% of the total time. Total drivage amounted to 131m. In 1978 the corresponding values were 5.7m 3/m, 53% and the total tunnel drivage was 1490m." Channel Tunnel. On the United Kingdom side of the Channel Tunnel project, ground movements were largely restricted to the area that was being worked, with 90mm being measured in an inclinometer that was sited on the toeweight area situated immediately uphill of the toeprint (Kirland 1995). Engineers on the UK side of the project were satisfied of this localized ground movement, though, when these ground movements stopped or quickly stabilized after construction work stopped (Kirkland 1995). By contrast, engineers on the French side of the project were confronted with the presence of faults with comparatively large displacements, as well as a thinner chalk marl that dipped at a more acute angle compared to the United Kingdom side of the project (Kirkland 1995). According to Kirkland (1995, p. 48), "This dictated the choice of closed-face tunnel boring machines that could permit exploratory drilling ahead of the tunnel face as and when required." Generally, no major geological problems were encountered on either side of the Channel Tunnel project, although engineers on the French side of the project experienced inflows fully 20 times as severe as the United Kingdom side (Kirkland 1995). In sum, Kirkland (1995, p. 49) concludes that, "Despite [the constraints encountered], the ground conditions tunneled through were better than those anticipated at the start of the tunnel boring machine drives."

Comparisons

The vastly different ground conditions encountered at the Seikan Tunnel site compared to the conditions encountered by the United Kingdom and the French sides of the Channel Tunnel project dictated the types of tunneling methods that could be used. Although more efficient...

There were some different outcomes concerning the original expectations of engineers concerning what ground conditions they would encounter in the tunnel boring process, with Japanese engineers encountered worse conditions than they expected, and UK and French engineers encountered better conditions than they expected.
Discussion and Conclusion

The Channel Tunnel was the realization of a centuries' old idea but the Seikan Tunnel is the manifestation of a much more recent initiative. Nevertheless, the fundamental goals of the Channel Tunnel and the Seikan Tunnel are virtually identical, the engineers on these two projects encountered significantly different ground conditions during their exactions. The fact that these monumental tunneling projects could be accomplished at all is noteworthy, and the fact that both projects were completed with minimal casualties is testament to the professionalism of the enterprise. The research showed that Japanese engineers were frustrated in their efforts to use the more efficient tunnel boring machines employed by their UK and French counterparts, but these engineers also prevailed by using drill-and-blast methods that required more time and therefore more expense.