Method for diversion construction of closure gap of steel cofferdam under open sea unshielded condition by down-penetrating method

Abstract

The invention discloses a method for the diversion construction of a closure gap of a steel cofferdam under an open sea unshielded condition by a down-penetrating method. The method comprises the following steps: A, driving parts of steel sheet piles on one side of the closure gap of the steel cofferdam in the low-tide period to be lower than a prescribed value to form a diversion overflow passage; B, penetrating and driving the steel sheet piles at the closure gap till completing the closing of the closure gap; C, pulling up the steel sheet piles forming the diversion overflow passage to the design elevation to reset the steel sheet piles; and D, penetrating and driving compartment piles between the reset steel sheet piles, riprapping rocks in formed compartments, and cutting off the diversion overflow passage, so as to complete the closing construction of the closure gap of the steel cofferdam. The method has the advantages that the diversion closing construction of the closure gap of the steel cofferdam is realized under the open sea unshielded condition; the construction is simple and fast, and the construction efficiency is high; the diversion effect is good, and the security coefficient of the steel cofferdam is high; and the steel sheet piles are constructed at the low-tide level when being welded by a platform construction method, so that the construction security coefficient is high.

Description

technical field [0001] The invention relates to the construction technology of a steel cofferdam, in particular to a construction method for channel diversion of a steel cofferdam without cover in the open sea by a downward insertion method. Background technique [0002] Caps in deep water foundations are generally constructed using the "cofferdam method", which uses cofferdams to create a working space for dry construction caps, and steel cofferdams are a commonly used cofferdam. When carrying out cofferdam construction, it is necessary to close the dragon mouth in the final stage of construction. When construction is carried out at sea, the tidal range is large due to the influence of monsoons, typhoons, foggy days, and tidal floods. During the flood season, the swell is larger and the tide time is faster. When the steel sheet pile mouth is closed, due to the impact of the tide, the low tide time is short, and the closing time of the sea mouth will be seriously insufficie...

AI Technical Summary

Problems solved by technology

When construction is carried out at sea, affected by monsoons, typhoons, foggy days, and tidal floods, the tidal range is large

During the flood season, the swell is larger and the tide time is faster. When the steel sheet pile mouth is closed, due to the impact of the tide, the low tide time is short, and the closing time of the sea mouth will be seriously insufficient, which will cause great damage to the closing construction of the steel cofferdam. difficulty

[0003] Especially, when carrying out offshore construction, due to the large inner area of ​​the cofferdam, the water level difference generated when seawater ebbs and flows will cause great pressure on the steel cofferdam, and the water flow caused by the water level difference must flow from the dragon mouth. Inflow or outflow, which will bring great difficulty to close the dragon's mouth

In addition, the construction in the open sea also has the following problems: (1) Due to the unprotected island operation in the open sea, the construction conditions are difficult and the construction is difficult; (2) There are many winds and waves, the construction time is limited, and the construction needs to be completed before the typhoon arrives, and the construction period is tight; ( 3) Affected by the tide level, the water level difference between the inside and outside of the steel cofferdam is about ±3.0m, and the water flow at the dragon mouth is turbulent, making it difficult to close the dragon mouth; (4) With the gradual closure of the diversion section, the water outlet decreases and the water flow velocity increases; The water flow is turbulent, and the sediment is washed away, affecting the stability of the platform and endangering the safety of construction personnel

Images