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CRANE È PE 2010" Lowe
Cross section of the pier, showing the design and positioning of the three types of piles in relation to the decking they support.
It was
better alignment and positioning of Piles in driving. therefore decided that Piles would be driven from a floating Universal Rig with adjustable leads to drive all three types of Piles over templates set up on false Piles. There was some difficulty in procuring a suitable barge locally for this rig but the Pontoon selected, and now in use, was adapted to fully cope with all eventualities by having "Camel back” out- riggers securely lashed at the bows over which the rig was mounted, to give the Pontoon added stability. The Pile rig, with adjustable leads 71'4" long with a 9'0" extension if necessary, was mounted on a Girder Platform. A total of 5 single drum and 1 Hammer Winch, all steam driven from a 40 H.P. Boiler, oil-fired and mounted in the hold, are in use on the Pile Driving Pontoon for the performance of the various functions, i.e., positioning of pontoon, pile lifting & leads adjustment to batter angle required. For driving, a single acting Vulcan No. 1 Hammer with a 5000 lbs. Ram and 27" stroke with a rated striking energy of 11250 ft. lbs. and a total weight of 11200 lbs. fully mounted, was selected and procured by the General Contractors. The stroke of this hammer if need arises is adjustable to 36" with a correspond- ing increase of the striking energy to 15000 Ft. lbs. which it was felt would leave ample margin for all eventualities encountered in the driving of the Piles. The Rig itself was locally designed and made up with the use of R.S. "H" Girders from the previous wharf in the frame and for the leads. For False Piles and Template beams these salvaged R.S. "H" Girders 12 X 15" were also put to use. False Piles and templates are carried ahead 3-4 Bents at a time with a total of 24 to 32 Piles driveable with one set-up. Piles are delivered to the driving Barge and Rig by a Lifting Pontoon equipped with compressed air operated winches over a 55′0′′ Shearleg of 25 tons lifting capacity. Piles up to 75'0" were suspended from 2 points and those of 80′0′′ and over, at 3 lifting points by means of compensation slings.
When Piles are positioned in the templates and the maximum penetration into the sea-bed under their own weight plus that of the hammer attained, driving to elevation of head & "set" prescribed is started over a short "Yacal" timber dully encased in M.S. Plates and inserted into the "standard" base of the "Vulcan" hammer and set onto the Pile head. Pile heads are further protected by cushions of coiled hemp inserted between the lower end of the "Dolly" and the Pile head.
Contrary to practice elsewhere it has not been deemed or found necessary in the local sea-bed to position Piles by "jetting" to within a few feet of final grade, but driving by hammer commences the moment the Pile has attained maximum penetration under its own weight. The various phases of this work are amply illustrated in the accompany- ing photos and all that may need further mention is that the Templates once spotted insure almost perfect alignment of Piles under normal sea-bed conditions.
Wharf Deck, The Pier deck is a 10′′ Concrete slab, with a 3′′ thick wearing surface to be poured when the rail system has been installed. Edge Girders, longitudinal centre and transverse Beams are poured in forms of 2′′ thick O.P., tongue and grooved and supported on 6 X 10′′ Girders parallel to the centre line of the Wharf. These rest on 8" X 12" transverse clamps which in turn are supported on short 8" X 12′′ toggles, Toggles and clamps are bolted around the Piles and in view of the batter angle of Piles, the provision of hangers from the Pile top to augment the friction support has not been found necessary.
Two views of the pier decking prior to final concreting. The upper view shows the formwork connecting the beams with the tops of the piles, and the lower picture, the decking steel being placed.
Concrete for Deck Beams, Edge Girders & Slab is a nominal 1: 6 Mix with graded and proportioned 1-1 2′′ Aggregate. All concrete is vibrated in the forms with high speed internal vibrators similar to those used for the Piles, the water content also being rigidly controlled. With the use of carefully graded and proportioned machine crushed Aggregates obtained from Morrison Hill Quarry and rigid water control, this "leaner" mix is producing practically the same 28 days strength as the "richer" Pile Concrete mix, with 3 days and 7 days at average 4000 lbs. and 5600 lbs. respectively as Crushing loads per sq. inch. Deck Beams, Girders and Slabs will require a total pour of approx. 64,000 cu.ft. of which approx. one-third has been done to-date.
A complete Rail-system, prefabricated in the UK, will be laid flush with the finished concrete wearing surface of the Deck to transfer cargo rapidly to transit sheds and godowns.
To keep mooring ropes clear of the Deck at the Praya end and in order not to impede traffic over the wharf, the inshore bollards are mounted on a bollard platform elevated 11′0′′ above finished Deck level of the wharf and designed to take the maximum pull of hawsers while leaving a clear space underneath for the passage of all traffic.
Special Wharf lighting will be installed to give 3 minimum of 1 foot candle at any part of the wharf, yet screened from the bridge of incoming vessels. This lighting system, using the latest fittings made for this purpose, will be provided with Mercury vapour lamps and the whole will be supplied and installed by the British General Electric Company.
The Wharf is expected to be completed and in operation in the autumn of this year provided no considerable delays in shipment of necessary materials such as springs, rails etc.
occur.
The Wharf Decking when completed will measure 700' X 50 and the total quantities of materials used in its construction will be as follows:
Cement Concrete
M. S. Reinforcing Steel Miscellaneous Steel Fittings Springs and Spring Casings
Yacal Hardwood for whalings and Rubbing pces. Rail materials
140,000 cuft.
730 tons
530 tons
354 Nos.
3500 cuft.
120 tons.
We gratefully acknowledge the preparation of the descrip- tive matter for this article by Mr G. R. Huber of MarsnIGA Hong Kong China Ltd.
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