Design method of negative buoyancy immersed tube

Abstract

The invention relates to the technical field of immersed tube tunnel construction, in particular to a design method of a negative buoyancy immersed tube. The method does not need to consider the design of a freeboard adjustment layer or consider the design contradiction between a freeboard value and floating resistance in an operation period, through the design thickness of ballast concrete determined by meeting the structural arrangement requirement, whether the preset first anti-floating coefficient is exceeded or not is inversely calculated, so that negative buoyancy larger than the corresponding preset requirement is obtained, then the design thickness of the first ballast concrete and the design thickness of the second ballast concrete are distributed according to the thickness calculated when the negative buoyancy is equal to the first anti-floating coefficient, it is effectively guaranteed that the immersed tube can meet the negative buoyancy requirement in the sinking and buttjoint stage specified by the existing specification, the negative buoyancy requirement after replacement of a ballast water tank is completed through butt joint specified by the existing specificationcan be met, meanwhile, the bearing capacity requirement of a transport ship is lowered, the lifting force needed in the immersed tube installation process can be reduced, the installation risk is reduced, and the transportation and installation cost is reduced.

Description

technical field [0001] The invention relates to the technical field of immersed tube tunnel construction, in particular to a design method for a negative buoyancy immersed tube. Background technique [0002] The buoyancy design must be considered in the structural design of the immersed tube, including the selection of the freeboard and the checking calculation of the anti-floating safety factor. In the prior art, the pipe joints with positive freeboard are used, that is, when the pipe joints are floating, the pipe joints can float in water, and the top surface of the pipe joints must be exposed to the water surface. In order to ensure the safety and stability of the pipe joint during floating, the pipe joint must be adjusted to the design freeboard value through the ballast water tank system installed inside the pipe joint before floating. The design freeboard value (exposed height) is usually 10- 30cm, and then using the self-floating characteristics of the immersed tube ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome that the design of immersed tubes in the prior art adopts the design of positive freeboard, which leads to a large section height of pipe joints, which in turn increases the amount of engineering work such as main structure and foundation groove backfill, and increases the cost of prefabrication and construction. Large and difficult construction problems, a design method for negative buoyancy immersed tubes is provided

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