| 摘要 |
<p>The invention relates to a new form of tunnel crossing which requires shorter accessways and are cheaper to construct than existing tunnels. The invention utilizes immersed tunnel units but which are supported on headstocks (2) which are held above the see floor by appropriate piles (3), yet are maintained at sufficient depth so as not to interfere with the passage of shipping. The immersed tunnel elements (14) are floated into position and are secured by tiedowns or jacks (15) to the headstocks (2). These tunnel elements are then joined to the mined tunnel to form a water crossing.</p> |
