XN000022-1972-07-03 — Page 12

4

Monday, July 3, 1972

In advance of the Island connections to the tunnel it was necessary to construct an extension to the Bowrington Canal comprising a culvert 1,000

Problems in dealing with large inflows of ground

especially since filling for the reclaimed area had

feet long and 40 feet wide.

water had to be overcome;

little chance to settle and large voids were encountered. The problems of incoming ground water were particularly difficult immediately at the back of

the seawall and special precast sections were used at this location to overcome the difficulties.

The remainder of the canal roof is supported on precast concrete piles some of which are 90 feet in length. Side walls were precast and hung from edge beams at roof level. The canal invert slab is cast directly onto the ground below, with an intervening rock-filter layer, and is thus able to move independently of the roof structure under the action of water pressure. Work on this extension began in August 1967 and was completed in March 1969

at a cost of HK$2.7 million.

Construction of the elevated roadway within Canal Road, ultimately to provide a direct route between Happy Valley area and the Waterfront Road or Harbour Tunnel, was commenced at an early date (in March 1965) to provide

sufficient time for overcoming anticipated foundation difficulties.

expected because of two major reasons:-

(1) Foundations were to be constructed below invert level

of the existing Bowrington Canal, which occupied a substantial part of the area of Canal Road. The canal had to remain in use, and during the rainy season could not be obstructed by temporary works.

(2) A number of old adjacent buildings were structurally

unsound, and the effect of ground vibration during piling could not be accurately predicted.

These were

/Particular