June_1970 — Page 32

CROSS-HARBOUR TUNNEL CO. LTD.

SCOTT WILSON KIRKPATRICK & PARTNERS

FREEMAN FOX & PARTNERS

Assisted by the following consultants

ROBERT MATTHEW, JOHNSON-MARSHALL

& PARTNERS

J. ROGER PRESTON & PARTNERS

LANGDON EVERY AND SEAH

TRANS HARBOUR CONSTRUCTORS LTD.

(consortium of COSTAIN INTERNATIONAL RAYMOND INTERNATIONAL and PAUL Y. CONSTRUCTION CO. LTD.)

REDPATH DORMAN LONG NV PHILIPS GLOEILAMPENFABRIEKEN.

cofferdam formed within Cause- way Bay typhoon shelter, Hong Kong Island.

Electrical and mechanical plant and equipment, finishes and administration building.

North ramp

The North ramp is in three sec- tions: Toll plaza at existing ground level; open ramp down to the north portal; and cut-and-cover construction between the portal and the north ven- ulation building.

The open ramp and cut-and-cover

Existing sea bed

.

client

consulting

building services (administration building)

quantity surveyors (administration building)

main contractors

principal sub-contractors

construction are both formed within contiguous bored-pile walls which pro- vide both cut off to ground water flow and structural elements to retain the adjacent ground. In the deeper sec- tions heavy bracing is required be- tween the piled walls; in the cut-and- cover section this is provided in the roof, while in the open section cross members are introduced which also members are introduced which also support louvres.

In Fig. 2 a typical cross section through the open ramp shows the bored piling, faced with precast units. Any seepage through the bored pile

wall is collected behind the facing units and led away into a ground-water drainage system.

A comprehensive under-drainage system beneath the road construction in the open ramp provides complete relief of water pressure. The bored-pile cut-off will reduce ground-water flow to minor proportions which can be handled by the system.

Fig. 3 shows a typical cross section of the ramp in cut-and-cover. Here the barrel-vault arches support the over- burden while the bottom slab is de- signed to resist full hydrostatic uplift.

Ventilation buildings

The original intention was to con- struct the North ventilation building inside a conventional sheetpiled and strutted excavation put down in fill placed off the Hung Hom seawall. However it was realised that, with the bottom of excavation about 70ft. be- low high-water mark, the design of this temporary work would be more com- plex than that of the permanent work within it and that its construction might be fraught with difficulties.

The contractor elected to construct the building as a steel and reinforced concrete caisson to be floated-in and

Tsim Sha Tsui

1

5'-0 Rock blanket

4′-0′′ filter bed

Granular fill

ventilation

TOO

TYPICAL CROSS SECTION

Granular filt

KELLET ISLAND

South ventilation building

Causeway Bay

Causeway bay typhoon shelter

Kowloon Cant.

North ventilation building

VICTORIA HARBOUR

Victoria park

Mile X

Feet 1000

1000 scale

2000

Far East BUILDER, June 1970