Affected by complex strata, large-diameter bored piles offshore often deform during the installation of casings, which affects subsequent pile foundation construction.

The "Adaptive Pushing-Type Casing Repair Device" independently developed by Zhejiang Zhongrui Heavy Industry Technology Co., Ltd. has recently been successfully applied in the Ningbo-Xiangshan suburban railway Xiangshan Port Sea-Crossing Bridge project!

▲The adaptive pushing-type casing repair device at the site in Xiangshan

During the construction of the bored piles for the main pier of this project, drilling was found to be difficult at some pile positions, and block stones, boulders, and foreign objects were successively found in some pile holes. At different elevations within the casings, the drill bit became stuck and could not continue drilling. After underwater probing, the deformation conditions were found to be very complex:

In response to the complex working conditions of this project, the "Adaptive Pushing-Type Casing Repair Device" developed and manufactured by Zhejiang Zhongrui was put into the project for casing correction work. As of January 11, the repair of casings for a total of 5 pile holes had been completed, among which the casing repair device worked for 15 days; the most complex deformation, hole No. 69#-26, took 6.5 days; the others were hole No. 69#-3, 3 days; hole No. 69#-18, 4.5 days; hole No. 69#-2, 0.5 days; and hole No. 71#-8, 0.5 days. The corrected casings all met the standards for continued construction, and the use effect won the client's approval!

The adaptive casing repair device consists of two parts: the correction system (main unit) and the pushing device. During operation, the main support and the two wing auxiliary supports serve as the base surface, and the deformed surface is pushed synchronously by the upper and lower oil cylinders until repaired.

This equipment is suitable for the repair of large-diameter casings within a construction depth of 60 m and Φ2.9 to Φ4.0 m, with a pushing force of up to 800 t. The equipment mainly has the followingfour major advantages:

Intelligent:It has adaptive functions such as automatic underwater hole depth monitoring, azimuth monitoring, underwater leveling, and oil cylinder displacement monitoring;

Efficient:The entire process is mechanized, with accurate positioning and high operating efficiency;

Economical:The single-hole repair efficiency is high, effectively solving schedule impacts caused by working face reasons, with good overall economy;

Safe:It replaces manual underwater cutting and is safer.