Cofferdam construction method for deepwater hard rock back-cover-free steel plate pile

Abstract

The invention discloses a cofferdam construction method for a deepwater hard rock back-cover-free steel plate pile. The cofferdam construction method comprises the following steps of: 1) during bearing platform drilling pile construction, synchronously constructing cofferdam construction stable piles which are positioned at the four corners of a cofferdam and on the middle part of the long side ofthe cofferdam; 2) performing lead hole slotting operation after construction for drilling the stable piles and a bearing platform pile foundation is completed; 3) dismounting a drilling platform, andmounting a Z-shaped bottom-support bracket of inner support; 4) utilizing a crane for stacking and dropping inner support to designed elevation in a layered mode; 5) welding a grouting tube at the inner side of a bottom slot hole of the steel plate pile, and infiltrating the bottom of the steel plate pile to a slotting area; 6) after the cofferdam is formed, pouring cement paste into a grouting tube for sealing a water permeable channel on the bottom of the cofferdam; 7) adopting large-power water pumping equipment to forcibly pump water and stop leakage; 8) converting inner support dead loadto the side wall of the cofferdam from the Z-shaped bottom-support bracket in a water pumping process, and connecting cofferdam edges to the stable piles; and 9) after water pumping is ended, dismounting the Z-shaped bottom-support bracket, starting excavation operation and the like. The cofferdam construction method can be applied to replace most of a double-wall steel cofferdam construction scheme, so that temporary cofferdam engineering amount is greatly saved, and application range of the steel plate pile cofferdam technology is greatly expanded.

Description

technical field [0001] The invention relates to the field of bridge construction, in particular to a construction method for deep-water hard rock unsealed steel sheet pile cofferdams. Background technique [0002] The construction of bridge caps requires the use of cofferdams to provide a dry environment for operations. In domestic deep water (above 15m above water) and similar hard rock geological conditions, the bedrock is generally blasted underwater, and then the double-walled casing is used to float and lower it into place for construction. It mainly has the following problems: [0003] 1. The lowering of the double-walled cofferdam requires underwater blasting of the bedrock. The processing of the cofferdam is difficult, and the construction requires a large amount of marine machinery and equipment, and it is difficult to recycle, with high cost and long construction period; [0004] 2. Double-wall steel cofferdams are used for construction, which requires a large thi...

AI Technical Summary

Problems solved by technology

[0003] 1. The lowering of the double-walled cofferdam requires underwater blasting of the bedrock. The processing of the cofferdam is difficult, and the construction requires a large amount of marine machinery and equipment, and it is difficult to recycle, with high cost and long construction period;

[0004] 2. Double-wall steel cofferdams are used for construction, which requires a large thickness of bottom-sealing concrete to meet the stability requirements of the base after pumping (generally, the water depth increases by 2-3m, and the bottom-sealing concrete needs to be increased by 1m), which greatly increases the excavation of the foundation pit. depth, so that the cofferdam needs to be anchored deeper into the soil, and at the same time, the safety risk during the excavation of the foundation pit is multiplied;

[0005] 3. If the steel sheet pile cofferdam is used for construction, the hard rock cannot be driven in, and the depth of the steel sheet pile is not deep enough for construction;

However, for cofferdams in deep water areas, this method cannot meet the stress requirements under the action of high water head;

[0007] 5. For the first construction of the internal support, the traditional method is to use large floating cranes or distributed jacks for integral lowering. This method has a large amount of on-site assembly work, a long construction period, and problems such as high-altitude operations, and the lowering method is complicated and has high safety risks. , and poor economy

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