Foundation construction: Latest techniques and equipment
By Helen Wright03 June 2011
Ambitious new projects are shaping the latest equipment launches in the foundations sector and pushing the limits of existing current machinery and construction techniques.
Rising energy costs, for example, are driving architects to improve environmental designs for buildings, and contractors are increasingly specialising in challenging projects including installing geothermal piles and wind turbine foundations.
Meanwhile, foundation equipment manufacturers report that an increasing number of large infrastructure projects around the world are fuelling demand from contractors for heavy, multipurpose piling machines with large capacities.
In April, for example, IHC Fundex Equipment unveiled the largest mobile piling machine it has ever manufactured in response to a customer request. Weighing over 300 tonnes, the FPD5000 has been designed for diverse methods of piling but can also be used as a crane. IHC Fundex said the machine was built for a customer in Brazil and will be put to work on the construction of a new airport.
The FPD5000 can be used as a 275 tonne capacity crane and can be modified with additional winches and cylinders to become a dedicated pile driving machine, capable of working with a maximum load of about 65 tonnes for the hammer and pile.
The machine has a 29 m boom in pile driving configuration and a standard 60 m length for lifting purposes. It can be disassembled relatively easily into separate pieces - the body of the machine weighs about 50 tonnes and is transported seperately from the carrier and tracks.
Meanwhile, Soilmec has teamed up with Caterpillar to produce its latest heavy duty model - the SC-65 lattice boom crawler crane. Soilmec showcased a prototype at last year's Bauma Germany show, and the SC-65 has now been brought to the market.
The machine has undergone extensive testing and improvements have been made to its design. Managing director of Soilmec, Simone Trevisani, said that through the co-operation with Caterpillar, the company aimed to build a leading range of products for the foundation crane sector, backed by a global support network.
"These machines are not an adaption of standard Caterpillar excavators. The turrets are designed by Soilmec, integrating the best Caterpillar technological solutions, specifically developed for this project," Mr Trevisani said.
"At Bauma 2010, the SC-65 was just a preliminary prototype. Now it has been validated on the field, and some improvements have been implemented thanks to feedback coming from the jobsite," he added.
The capacity of the SC-65 is 65.7 tonnes at a working radius of 3.5 m and maximum boom length is 51 m. Power is from a 403 kW diesel engine and maximum line pull is 24 tonnes.
The hydraulic crawler is the first from the Italian manufacturer with electro-hydraulic proportional controls, and the machine can be set up in crane, hydraulic grab, cable grab and hydraulic rotary configurations.
Such versatility from heavy duty machines is increasingly in demand as mega projects gets underway in developing markets, where investment in infrastructure is growing.
In Kuwait, for example, seven Liebherr SH 855 HD hydraulic crawler cranes - four HS 855 HDs and three HS 885 HDs - have been compacting a huge ground area of
Contractor Ahmadiah Group is preparing the desert ground for new Jaber Al-Ahmad City, which will be situated 22 km west of Kuwait City and feature around 7000 housing estates, including schools and hospitals.
The Liebherr units have been working in two 9-hour shifts per day, 25 days a month on a project that is set to last a total of 18 months. Each unit carries out around 600 automatic work cycles per shift using Liebherr's Litronic control system.
The 90 tonne HS 855 HD is fitted with two 25 tonne winches and the 125 tonne HS 885 HD with two 30 tonne winches. The ground was compacted using a drop weight of 25 tonnes at a dropping height of 29 m.
In addition to adapting to the scale of new infrastructure projects, foundation contractors are increasingly tasked with integrating environmentally friendly technologies to new builds.
On a € 165 million (US$ 236 million) project to construct a new hospital in Monselice, Italy, for example, the displacement piles double up as geothermal wells.
A Soilmec SR-80 piling machine was selected by contractor Trevi for the work inserting 40 km of 600 mm diameter displacement piles at depths ranging from 17 m to 24 m. Soilmec said it took on average 30 minutes to install each geothermal pile - drilling the hole took just 8 minutes, but concreting and inserting the reinforcement cage holding the geothermal loop required more time.
The thermal exchange between the surrounding soil and the concrete piles is aided by the fact that the water table is located immediately under ground level. For easy connection with the future slab, concrete rings were placed on top of the piles to compensate for the difference between ground and slab level.
The SR-80, which weighs 90 tonnes and can deliver 292 kNm in torque, ensured good productivity - Trevi was able to install an average of 16 piles, including the rig tracking phase between piles, per day.
As governments worldwide invest in low-carbon, renewable energy, the installation of wind turbines is another application for which foundation equipment is increasingly in demand. In May this year, for example, Bachy Soletanche won a UK£ 0.5 million (US$ 0.8 million) contract in the UK to install the piling for four large wind turbines on a new wind farm. Located near the Solway Firth in Cumbria, the Hellrigg Wind Farm is set to contribute to meeting the UK's target of 15% renewable energy by 2015.
Contractor Hanson used Bachy Soletanche's Heavy Duty Large Diameter Auger (LDA) rigs and the piles are being constructed with segmental casing and under a bentonite suspension due to the properties of the soil and the unstable ground. Each base will contain 16 900 mm diameter piles which vary in depth from
25 m to 38 m.
Bachy Soletanche contracts manager Steve Mallinson said the project was one of the company's more unusual jobs, "The site is in a remote location and we are using large piling rigs and cranes and making sure that there's as little disruption as possible to the surrounding area".
New equipment to improve the efficiency of foundation works is also under constant development. To ease the handling of sheet piles, for example, PTC (part of the Fayat Group) has produced a new concept of clamp, the Tiltex 60t. Mounted on a PH Vibrodriver, the clamp can tilt, grab and lift sheet piles lying on the ground helping to reduceon-site manula labour.
With a clamping force of 60 tons (60.9 tonnes), the new Tiltex provides a steady grip for heavy duty jobs. It can be used with a wide range of PTC excavator mounted models including the 6PHFV, 8PHFV, 7PHF, 10PHF and 13PH.
Piling technology is also under constant review from equipment manufacturers, and several new systems for complex applications have been launched.
Liebherr has developed new software to help make deep foundation work more efficient. The company's deep foundation machinery is equipped with Liebherr's new PDE process data recording system, which relays data such as depth, geometry and the amount of suspension in real time to the operator's cab.
The PDE process data recording system also enables recording of process-related values on a memory card in the operator's cab for a large number of deep foundation methods. This can be evaluated on a computer after the work has been done, enabling the generation of individual site protocols for proof of quality and to facilitate the settlement of the site.
Meanwhile, Pile Dynamics has developed a new viewer for its pile installation recorder (PIR). The PIR is an automated monitoring equipment designed to aid in the installation and quality control procedures of augered cast-in-place and continuous flight auger piles.
The PIR viewer is a hand-held wireless device that allows an inspector or piling foreman to view what the main unit of the PIR in the crane cabin is displaying - the progress of the drilling and grouting operation is seen in real time on both the main unit and on the PIR Viewer.
The development of technology to check and record the quality of foundations has clear benefits for contractors, and demonstrates that equipment manufacturers not only have increased productivity at the forefront of their latest designs, but are also adapting to the increasingly complex demands of the industry.iC