| 摘要 |
<p>The hydraulic thrust system allows a lower roadway to be inserted below one in use without interruption of traffic on the latter. The roadway comprises a prefabricated structure assembled during the thrusting operation in a penetrating structure, and a provisional supporting platform for the roadway in use rests on supports in the ground clear of the penetration zone. The platform is strong enough to sustain the existing roadway structure, excluding the momentary overloads due to traffic. Removable wedges fit between the platform and the penetrating structure. There may be girders on the underside of the platform, running in the direction of penetration, and against which rollers on the penetrating structure bear.</p> |
