Client: Electrical and Mechanical Services Department
Contract No.: 1020EM12A
Project Title: District Cooling System at Kai Tak Development Phase III (Package A) – Chilled Water Laying Works
Main Contractor: Wo Hing Construction Co., Ltd.
Sub-contract Works: Installation of ID1200mm, 1500mm and 2800mm Jacking Pipes by TBM 1200DHL,1500DHL and 2800DH
Total Length: 1200m
Duration of works：2013 – 2015
Significant Works of TBM Pipe Jacking
The project was located in Kai Tak Development Phase III (Package A). The major section of the pipe jacking works was laying ID2800mm twin pipes by Tunnel Boring Machine (TBM2800DH) trenchless method across Kai Tak Nullah underneath the seabed, where the distance between Launching pit and Receiving Pit was 330m.
Ground Water：
The Launching and Receiving Pits were constructed 25m deep nearby the sea shore, under high pressure of groundwater. Even a small hole or a chink in the sheet pile or concrete bedding would cause a fast spurt of underground salt water into the pits. Before cutting sheet pile for TBM, a huge amount of grouting bore holes with grouting pipes were made around the Launching and Receiving Pits and suitable grouting materials were injected to prevent groundwater penetration during pushing in and out of TBM.
Silt in seabed :
The Tunneling Boring Machine was operated underneath seabed of the Nullah. The TBM and Jacking Pipes were tightly held up by silt, leading to great resistance. The situation could not be improved even all Hydraulic Jacks were in full power. Technical Staff and TBM Operators were collaborated to look for feasible solutions. With an in-depth analysis and execution of solution, the project was able to be proceeded and was completed as scheduled.
