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...
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