Hydraulic tunnel driving process - uses narrow steel sheath plates which are pressed forward for spoil removal ahead of tunnel shell

摘要

The structural unit (2) to be pushed forward, is partially or completely sheathed by narrow, abutting, lengthways aligned steel sheet element (a) along its whole length. The sheets are successively driven forwards individually by special rams. The ground is removed under the protection of these. When they have all been forwarded, the structural unit is thrust forward under the protection of the sheath. The top and side surfaces may be covered by these steel elements. Lubricant may be provided in the gaps between sheath elements and structure.