Understanding the Flexible Tunnel Shed
The flexible tunnel shed is a shed-shaped rockfall protection system composed of supporting structures, metal flexible nets, energy dissipation devices, support ropes and other components. All components can be factory-processed and produced, and assembled on site. It is simple and fast to construct, has a long service life and low construction cost. At the same time, the structure is relatively light, which can be effectively combined with bridges, reducing the requirements for foundation and site conditions, and solving the problem of rockfall protection at the connection of bridges and tunnels where there is no roadbed condition.
The protective capacity of the Flexible Tunnel Shed ranges from 500 kJ to 2000 kJ. When the ultimate protective energy level exceeds 2000 kJ, a special design should be carried out.
Category Introduction
Flexible overpasses are classified mainly according to the form of the supporting structure, and can be divided into (a) arched flexible overpasses, (b) frame-type flexible overpasses, (c) cantilever-type flexible overpasses, etc. They can also be combined using any of these three forms. The supporting structure materials can be steel, reinforced concrete or other materials.
Based on the force characteristics and protective effect of the flexible shelter tunnel buffer system, it can be classified into (e) the throw-type tunnel shelter and (f) the interception-type shelter tunnel.
- The main protective feature of the throw-type shelter tunnel is the area for protecting against rockfalls.
- The protective feature of the interception-type shelter tunnel is that even when rockfalls fall into the buffer system, they remain within the system.
Main construction requirements
- The steel structure part of the arch frame at the outlet of the plate gate should be installed by segmental hoisting. First, install the column base and upright part of the arch frame, then assemble the three sections of the arc-shaped beam on the ground and hoist them up, fitting them together with the uprights. After installing two arch frames, immediately complete the installation of the tie rods and supports between the arch frames.
- The steel structure part of the middle section of the frame should be installed by means of overall hoisting. On the ground, the arch frame should be assembled as a whole in three sections and then lifted for installation. After each two arch frames are installed, the connection rods and supports between the arch frames should be installed immediately.
- When steel wire rope components are equipped with buffer units, they should be installed simultaneously with the steel wire rope components.
- For the base fixed by ground drilling anchor rods, it is advisable to level the installation area’s ground with mortar.
- When using a grating net, lay the grating net sheets on the uphill side of the support net and make the edges of each net sheet interlock with those of the support net through the binding between the grating net and the support net.
- The stitching connections between each flexible mesh and between the meshes and the supporting ropes should ensure that every edge mesh hole is connected.
