Shanghai is expanding its network of elevated highways with a new north ring road. The road leads through densely urbanized areas and calls for foundation installation methods that cause minimal impact on the environment: such as impact noise vibrations bentonite handling and construction speed. The client was looking for a new method that could address these issues and a web search lead to ICE’s resonance free hammer range.
 
After a number of technical discussions with the ICE sales team it was decided to do a joint test project to evaluate the possibility if using long steel casings for elevated highway foundations. The client designed the test to provide results for the vibration impact to the environment noise levels and to prove vibratory hammers can drive the piles to design depth. The test was interesting for ICE as we had an opportunity to test three hammer models from our rental fleet pushing the equipment to its limits and obtaining representative results that will establish our technology as leading. 
 
Engineers from the design institute prescribed 63m long casings. The 550mm diameter casing consisted of three sections: 15m + 15m + 33m. Thewall thickness was 14mm the top of the casing was strengthened with an extra ring of material to transfer the driving force into the casing without tearing of the casing. A total of 6 casings were to be driven to provide the foundation for a pedestrian lane ramp adjacent to an elevated highway.
 
The first hammer to be used was the 20RF fitted with a set of 81TC casing clamps. The 20RF is one of ICE’s lighter hammers that can work without vibration disturbances to the environment; it is typically used for driving and extracting sheet piles and SMW H-beams. The aim was to demonstrate the Resonance Free driving principle and make measurements with the Profound Vibra+ vibration monitor. The initial plan was to drive the first and perhaps second 15m section to depth with the 20RF but as the hammer still had working pressure we decided to see how deep the 20RF could drive the 63m casing. At an incredible 38m the 20RF had reached its limits and we moved the 815C in position. The 815C also uses the 81TC clamp set. Our calculations had shown that at -60m a hard clay layer would be reached and driving would be challenging and slow suggesting the need for additional ballast weight on the hammer.  As expected the 815C did well up to -60 meters and with 240 out of 350 bar working pressure remaining startedworking on the hard clay layer (N47). At this point the residents of neighboring farm houses that were scheduled for demolishing seized the opportunity to bring attention to their compensation dispute and came out to protest the 815C’s normal frequency vibrations. In order not to aggravate the residents the test was halted and it was decided to bring in the 1412C which at 13.5t has the additional weight to drive the pile down quickly. The 1412C is developed for larger casings and the 200TC double clamps could not fit the small diameter of the casing. We chose to weld a H-beam on top of the casing that would fit the 1412C’s 320TU clamp and drove the casing in this way. The 1412C drove the first pile down the remaining 3 meters within minutes but residents were adamant the test was stopped and 5 piles were left un-driven.
 
In consultation with the client we selected a second site further away from residential properties to generate sufficient data for the evaluation report. On the chosen site the 1412C drove the 63m long casing in a 30m and 33m section within 25 minutes each.
 
The test involved over twenty experts from many different sectors: the construction site manager a casing supplier welders design institute and the R&D department and the ICE rental team.
 
The test provided conclusive results:
• RF hammer proved its value – residents living close to the construction site did not notice any vibrations and did not object until normal frequency equipment was used and construction was halted under their pressure.
• The piles were driven to design depth by vibratory methods and analysis after 1 month showed that the bearing capacity of the piles was according to design specification
• Driving analysis of the 600mm diameter casings convinced the team that ICE hammers have the power to drive larger casings; in future designs larger casing diameters will be chosen to better fit existing equipment configurations. This will allow fewer casings to be driven for the same load capacity.
• The ICE Resonance Free is a low environmental impact method that is now green-lighted for inner city construction projects.