Underwater tunnel construction method suitable for ultra-shallow soil covering conditions

Abstract

The invention discloses an underwater tunnel construction method suitable for ultra-shallow earthing conditions. The underwater tunnel construction method includes: constructing a working shaft at a position outside a water area range and at each of two ends of axis of a to-be-built tunnel; jacking multiple steel pipes on the outer walls on two sides and at the bottom outside a to-be-built tunnel structure, laying a first freezing pipe in each steel pipe, and filling each steel pipe with concrete; paving multiple groove-shaped steel formworks underwater on a top plate of the to-be-built tunnel structure, underwater pouring concrete to the grooved-shaped steel formworks, and backfilling to reach an original riverbed level; constructing a second freezing pipe to the side wall of the groove-shaped steel formwork positioned on the outermost side; starting a freezing system to freeze surrounding soil; excavating the soil within a range of the to-be-built tunnel to complete construction of the to-be-built tunnel. The underwater tunnel construction method overcomes the defect that shield methods, mining methods and whole-section pipe roofing methods cannot be implemented under the ultra-shallow earthing conditions. Compared with immersed pipe methods and cofferdam open-cut methods, the underwater tunnel construction method has the advantages of low excavation depth of an underwater foundation pit, needlessness of floating transportation and immersion and small influence on navigation and flood control.

Description

technical field [0001] The invention belongs to the technical field of underground engineering, and relates to a construction method for constructing an underwater tunnel, which is applicable to the combination of underwater treatment and underground excavation under the condition of ultra-shallow soil covering. Background technique [0002] There are four commonly used construction methods for underwater tunnels: shield tunneling method, mining method, immersed tube method and cofferdam open cut method. In order to ensure the safety of construction and meet the needs of anti-floating, shield tunnels generally have a thickness of overlying soil not less than 1.0D (D is the outer diameter of the tunnel). There are also successful cases of crossing waters with a thickness of about 0.7D in various projects. . In mine method, for underwater tunnels, the thickness of overburden layer required varies according to different geological conditions, but generally not less than 1.5D. ...

AI Technical Summary

Problems solved by technology

The thickness of the covering layer required by the immersed tube method tunnel is small, and the covering layer may not even be required, but the underwater excavation and the floating and sinking of the pipe section during the construction period will have a certain impact on navigation

The cofferdam open cut method has no special requirements on the thickness of the covering soil, but it occupies a large area of ​​water during the construction period, and it cannot be implemented in rivers that require navigation or flood control.

In addition, the pipe curtain method can also realize the construction of underwater tunnels, but limited by the minimum covering soil thickness required for the construction of the top pipe curtain, the covering soil above the tunnel roof needs to be at least 4m

[0003] That is to say, in the prior art: the shield tunneling method and the mining method require a large covering soil thickness, and the immersed tube method and the cofferdam open cut method have little requirements on the covering soil thickness, but if there are navigation or flood control requirements, it may not be available. Implementation conditions; the thickness of the covering soil required by the pipe curtain method should not be less than 4m

When the construction environment has special restrictions, and it is necessary to excavate and construct underwater tunnels under the condition of ultra-shallow covering soil (such as when the minimum covering soil thickness is less than 4m), the existing technology cannot be implemented

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