| 摘要 |
The device comprises a hollowing machine endowed with a shield 1 and tubular formwork composed of a front form 3 coupled to the said machine and an inner form 2 which together with the surrounding ground make an annular space 4 into which the supporting concrete is injected. The front form 3 is composed of a ring 5 provided with a sealing means 6 in contact with the shield 1 and the inner form 2. The said ring 5, articulated to the shield 1 by means of hydraulic jacks 7 which are uniformly distributed around the perimeter of the tunnel, is longitudinally guided by means of sliding supports 13 in the shield 1, coupled to the hollowing machine via advancing mechanisms 14 and bears on an adjustable elastic arrangement 18, 20. The hydraulic jacks 7 are used as an arrangement for stabilising the ring 5. For this purpose, on the one hand the forward chambers 11 of the cylinders of these jacks exhibit respectively, on account of the presence of a rod 16 extending the rod 9 of the piston forwards, the same cross-section as the rear chambers 12, and on the other hand the assembly of forward and rear chambers 11, 12 are disposed in a series circuit 17 which is closed on itself. <IMAGE>
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