Construction of a new bridge across the Batang Rajang river in Sarawak, North-West Borneo is the most recent civil engineering project to use BSP International Foundations’ latest generation of hydraulic piling hammers to drive the 167 tubular steel piles required for the foundations.

The Shin Yang Group of companies, through its subsidiary Woodville Development Sdn Bhd, was awarded the approximate £30million (Ringgit-RM180 million) contract by the Sarawak Government to construct the bridge and associated approach and slip roads. Main contractor Perkerjaan Piasau Konkerit Sdn Bhd, the construction subsidiary of the Miri, Sarawak-based Shin Yang Group, began preliminary works in October last year. Initial piling for the foundations followed when two BSP CG300 hammers, together with power packs, were delivered to the site one of which was mounted on the contractor’s purpose-built ram lift piling barge.

As the first phase of the drive involved very soft soil conditions, detachable trips were supplied to allow the hammer to follow the pile without the need for the operator on the barge to continually pay out the hammer rope. During the final part of the drive, the pile was driven using the auto function of the controls set at 700mm stroke until the pile reached rock. A top drill was then set on the pile to drill the socket in the rock.

To suit the piling barge and allow quicker installation onto the leader, the hammers were fitted with backguides by BSP. In addition, one of the hammers was supplied with accessories to enable piles to be driven in a freely suspended mode whilst Perkerjaan Piasau Konkerit supplied its own pile helmets. These are suitable for the 56m long steel tubular piles which have a diameter of 1.5m, a wall thickness of 19mm and weigh 40t. Most of the 167 piles are vertical with a number to be driven at rakes of 1:6 and 1:8.

The 580m long main bridge span across the river will have foundations supported by piles infilled with reinforced concrete and driven 10m to 15m into rock. The pilecap of the main pier, located at the centre of the river, has been designed to withstand an impact of a 6,000t barge travelling downstream at six knots. It will be supported by 43 piles driven into a hard layer of rock in the riverbed. The soft material inside the pile is removed using the airlift method before the reverse circulation drill, with a top seated mounting, is installed.

Located six kilometers upstream from Sibu town centre, the bridge and approach road construction will have a total length of approximately 3.35 kilometers with an additional 3.24 kilometers of slip road. When completed in April 2006, the bridge will be 1,220 metres long and comprise four balanced cantilever spans and eight equal spans of 40 metres in length at each side. Specifications include a two-lane dual carriageway complete with barriers, footways, guard rails and street lighting etc. The bridge and associated roads within the project will link the local road system serving the town of Sibu and also the movement of local traffic in and out of the town.

BSP has been supplying civil engineering contractors in the Far East with piling equipment for many years and, as a result, has built up an enviable reputation in the region for hammer reliability, efficiency and product support. Civil engineers with Perkerjaan Piasau Konkerit have had previous experience of working with BSP hammers and this, coupled with the company’s reputation, were deciding factors in the contractor’s selection of the CG300s for this project.

The CG300 hammer is the largest model in BSP’s new CG range having a 20-tonne dropweight and developing a maximum impact energy of 300kNm at a maximum stroke of 1.5mts at 30 blows per minute. Each hammer working on the Sarawak project is powered by a BSP power pack fitted with a Caterpillar 3306 DITA diesel engine producing 325hp.

All BSP hydraulic hammers offer excellent versatility as they can be operated either from pile rig leaders or crane suspended. When working in the crane suspended mode, a tubular pile guide is used and connected directly to the bottom of the hammer cage. Piling helmets are also available which efficiently transfer hammer impact to the pile. A careful balance between the ram mass and the cage design result in a minimal weight for each hammer in the range.

At the heart of the CG range is the hammer’s hydraulic actuator, a design providing efficient performance which, for a given blow rate and energy transference, requires less fuel and reduced exhaust emissions. With a BSP control manifold valve, the Ipswich-based company’s range of hammers can be connected into an existing power supply from a hydraulic pile rig or crawler crane base. The company also offers a range of diesel powered ‘open circuit’ Hydropacks specifically designed to maximise hammer performance.

Controllability is a major feature of all BSP hammers as the well proven control panel is set up to deliver an infinitely variable stroke and blow rate. This allows precise delivery of energy to the pile, enabling the contractor to mazimise production rates, avoid pile damage and problems associated with pile run-away. Complementing the range of controls, BSP offers a stroke watch LCD readout developed as an economic means of displaying the energy and stroke of any of the hammers in the range. This hand held unit plugs into the same port on the side of the hammer control panel as the full monitoring kit.

There is no doubt BSP’s new CG hammer range’s simplicity of design together with a technically superior hydraulic system provide high operating efficiency and greater earnings potential for the contractor whatever the ground conditions.

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