Construction method of steel sheet pile collapse t

Construction method for steel sheet pile collapse treatment of bridge engineering

with the commencement of the construction of passenger dedicated lines and high-speed railways, pile foundation caps are mainly used for the bridge foundation, and the bridge foundation has also begun large-scale construction. Many problems have been encountered in the construction process of the foundation. These railway lines mostly pass through rivers, irrigation canals, low-lying ponds and other environments. During the construction, these sections are mostly deep-water foundation pits, which are often protected by steel sheet pile cofferdams, Due to the lack of construction and technical experience, steel sheet piles often collapse. This paper introduces the treatment method after the collapse of steel sheet pile in deep-water foundation pit of a bridge, for the reference of technicians

1 project overview

most of the structural dimensions of the bearing platform of a passenger dedicated line are 10.6 × fourteen point six × 3.0m、8.1 × 12.218 steel skylight upper suspended steel skylight 5 × 2.5m、8 × eleven × There are 12 structural types such as 2m, and the excavation depth is more than 5m, which belongs to deep foundation pit excavation construction. The excavation of the foundation of the river crossing bearing platform is relatively deep, and the construction of this part of the bearing platform is planned to adopt the construction of steel sheet pile cofferdam; According to the hydrological and geological conditions of the bridge, it is considered that the construction of steel sheet pile cofferdam has many advantages, such as short construction period, technology, which is of great significance for the study of computer control, simple, less space, safety, easy control of construction risks and so on. After the completion of bored piles, the construction platform of steel sheet piles shall be used as the construction platform of bored piles

biodegradable materials play a leading role. 2 construction process flow and treatment scheme

2.1 process flow

measurement and setting out → inserting and driving positioning steel sheet piles → setting up guide pile frame → cleaning steel sheet piles → inserting and driving steel sheet piles → setting up internal supports → pumping and plugging → construction of bearing platform and pier shaft → removing internal supports → pulling out steel sheet piles

2.2 construction treatment scheme

this foundation pit is the main pier of the river crossing continuous beam. Due to the tight construction period, after the steel sheet pile is closed, the first internal support is reinforced and then excavated. During the construction period, it is the local flood season, the river surges, and the steel sheet pile accidentally collapses under the impact of the river. When the steel sheet pile collapsed, I tried to pull out the steel sheet pile on site, but it could not be pulled out because the steel sheet pile was bent. Then it was decided to backfill the foundation pit after cutting off part of the steel sheet piles to prevent the intensification of the deformation of the steel sheet piles. After backfilling, a secondary piling platform was created, and a secondary steel sheet pile cofferdam was used to completely remove the collapsed steel sheet piles

2.2.1 inserting and driving of steel sheet piles

after the collapse of steel sheet piles, the foundation pit is backfilled after cutting off part of steel sheet piles. 2. After the successful installation of TestStar, a secondary piling platform is created, and then the measurement and setting out are carried out to insert and drive steel sheet piles

the steel sheet pile is lifted and inserted by a 50t crawler crane, and then the vibrating hammer is turned on to vibrate while inserting and driving. Before inserting and driving steel sheet piles, in order to ensure the smooth closure of steel sheet piles, the guide frame shall be driven first. When inserting and driving steel sheet piles, the first steel sheet pile must be inserted and driven correctly to avoid affecting the steel sheet piles behind. In the whole process of driving steel sheet pile cofferdam, one steel sheet pile can be inserted and driven at the beginning, that is, each steel sheet pile can be driven to the design position. When the last 20 steel sheet piles are left, they should be inserted first and then driven. If they are closed incorrectly, use chain fall or pulley group to pull them together, and then drive them to the design depth one by one

in the construction of steel sheet piles, the quality of driving and positioning should meet the following requirements: the width difference between the upper and lower openings of wedge-shaped piles should not be greater than 2% of the pile length when closing; The inclination after reaching the design elevation shall not be greater than 1%; In the process of driving steel sheet piles, when the guiding equipment fails and the top of steel sheet piles reaches the design elevation, the allowable deviation of plane position is 20cm for piling in water and 10cm for piling on land. Monitor whether it is within the allowable error range, and correct it in time if it is exceeded

precautions in the process of inserting and driving: ① before inserting and driving, the lock mouth should generally be coated with butter, sawdust and other mixtures, and putty and cotton should be used to caulk when assembling piles to prevent water leakage; ② The inserting and punching sequence shall be carried out according to the construction organization design, generally from the upstream to the downstream closure; ③ To insert and drive steel sheet piles, generally, all steel sheet piles should be inserted and driven to a stable depth one by one or group by group, and then driven to the design depth in turn. Under the condition of ensuring the vertical sinking of steel sheet piles, each steel sheet pile or group of steel sheet piles can also be driven to the design depth at one time; ④ When inserting and driving steel sheet piles, if the lifting equipment is not high enough, it is allowed to change the position of the lifting point, but the position of the point shall not be less than 1/3 of the length of the pile below the top of the pile; ⑤ Reliable guiding equipment must be provided for inserting and driving steel sheet piles to ensure the correct position of steel sheet piles