Covering-type silt prevention cover plate, silt prevention system and construction method of immersed tunnel gravel foundation bed

Abstract

The invention relates to a covering-type silt prevention cover plate of an immersed tunnel gravel foundation bed. The covering-type silt prevention cover plate of the immersed tunnel gravel foundation bed comprises a frame, wherein a plurality of ballast water tank bodies into which water can be filled and from which water can be drained are arranged in the frame, and lifting points are arranged on the frame. A plurality of canvas bags for containing silt are arranged above the ballast water tank bodies, a cover plate installation vessel comprises two floating bodies, the tops of the floating bodies are connected through a portal frame, lifting hooks are arranged on the portal frame, a lifting machine is arranged on the floating bodies, and desilting equipment is arranged on the cover plate installation vessel. By adopting the cover plate covering-type silt prevention scheme, the foundation bed can be fully covered, the complete isolation between the silt and the foundation bed is realized and the quality of the foundation bed is guaranteed; foreign objects falling onto the foundation bed during construction directly fall onto the cover plate and can be prevented from occurring on the foundation bed; since full-coverage silt prevention is adopted, the flattening operation of the foundation bed can be performed in advance and the construction progress is accelerated; no destruction is caused to the foundation bed and the integrity of the foundation bed is guaranteed.

Description

technical field [0001] The invention relates to a system and a method used in the construction of a subsea tunnel, in particular to a system and a method for anti-silting the foundation bed of an immersed tube tunnel. Background technique [0002] The underwater tunnel often adopts the immersed tube method. The entire tunnel immersed tube is composed of multiple pipe joints. The general standard pipe joint is 180m long and 37.95m wide. , the width of the ditch is 1.05m, the width of the gravel strip is 1.8m, the bed area of ​​each standard immersed tube reaches (42m×180 m) 7560㎡, and the exposure time of the gravel bed from the beginning of leveling to the installation of the immersed tube is about 12 days , due to the high average sediment content in seawater in some sea areas, and the fact that there is about 2m of silt on the original mud surface of the slope top of the foundation trench, the sediment concentration changes during the flood season, the dredging and sand mi...

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Problems solved by technology

[0003] The adverse effects of sedimentation on immersed tube tunnels mainly include: changing the mechanical characteristics of the crushed stone bed and affecting the force transmission effect of the bed structure; Changing the bulk density of seawater will affect the anti-floating safety of the immersed pipe joint; if there is a mud layer in the gravel cushion foundation, after the tunnel is in operation, the settlement of the immersed pipe will be too large and unsatisfactory due to the consolidation deformation of the mud. The uniform settlement exceeds the standard, and a large bending moment is generated in the pipe section, which may lead to cracking of the pipe section in severe cases

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