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Borehole Geophysics for the Shatin to Central Link

Service provided:
Geophysical borehole surveys along the TBM alignment
Location:
Wan Chai, Hong Kong SAR
Period of the service:
2015-2018
Sixense expertise used:

A challenging tunnel construction

In 2014, Dragages Hong Kong and Bouygues Joint Venture (DBJV) were selected to construct one of Hong Kong’s most technically challenging tunnels – part of the 6Km extension of the ongoing Shatin to Central Line – a strategic railway connecting Kowloon with the transit hub on Hong Kong Island.

The main challenge of the project is to construct the eastern and western tunnels by Tunnel Boring Machine (TBM) on Hong Kong Island, as both tunnels pass underneath the city’s busiest districts. Therefore, meticulous project planning and surface works are essential to aid the TBMs in progressing through an underground environment characterized by a large volume of pile obstructions and utilities.

Images of the project

60

Piles investigated (approx.)

20+

Surveys

36

Months

Geophysical surveys along the TBM alignment

In 2015, Sixense were appointed by the Dragages Hong Kong – Bouygues Joint Venture (DBJV) to undertake borehole geophysical surveys along the TBM alignment, to ensure that underground construction risks could be anticipated and managed. Consequently, a broad variety of geophysical survey methods were used by Sixense, enabling the detection and characterization of unknown existing foundations and unexpected obstructions along the TBM alignment.

Significant volumes of foundation removal work has been avoided as a result of the accurate detection and estimation of the individual obstruction characteristics and locations. Additionally numerous foundations, that were not expected, were identified as being located on the TBM alignment, and thus had to be removed.
On the Shatin to Central Link, the deployment of borehole geophysics has proven to be a cost-effective, productive, and accurate survey technique. As a result, it has helped mitigate the risks associated with tunneling works in densely developed urban areas.

Tags

Borehole electromagnetism Parallel Seismic Method Electric Cylinder™ & Cyljet™ Cross-Hole Electrical Imaging Ground Penetrating Radar Borehole magnetometry