| 摘要 |
<p>Internally lined tunnel has (I) an external cover of reinforced concrete, (II) an intermediate insulating sealing layer consisting of thin plastic sheets, such as plasticised PVC, fixed to the inner surface of the external cover, and (III) an internal lining consisting of prefabricated elements, such as reinforced concrete sheets, plastic tubes, fibre-cement sheets or metal plates, while a single fixing element serves to fix layer II and bring III onto the inner surface of the cover I. Used for underground railways, underground roads, or underground distribution systems. The tunnel is well insulated and sealed against the penetration of water. The tunnel can be produced more cheaply than tunnels with internal linings of poured concrete.</p> |
