Rapid urbanization has brought construction sites from the suburbs into the cities where they clash with existing structures, garner residents’ complaints, and threaten the foundations of critical infrastructure like metro and elevated highway. Under these circumstances specialized urban construction equipment such as the resonance free vibratory hammer are seeing rapid adoption.

In this article we look at two typical urban applications.

Nobody believed that houses adjacent to the construction site would not be impacted by the removal of the trestle bridge. The temporary structure was installed by electric vibro three years ago and the residents remembered the earth shattering experience that was. They were determined not to have to undergo a similar ordeal during the removal of the piles, some of which were only two meters away from their property. The residents called in experts from Zhejiang University to monitor the progress to ensure no damage was inflicted on their houses. Working under such intense scrutiny is no sinecure.

Zhejiang Electric, the company responsible for the construction work, decided they needed an ICE 28RF to extract the piles. This would enable the fastest project completion and rule out compensation payments to this hyper-vigilant neighborhood. The bridge casings had been in the river bed for 3 years and were pretty stuck, but the 2300RPM high frequency vibro extracted the piles efficiently without damage to the adjacent houses. Zhejiang University’s vibration monitoring team kept a close watch on their analysis equipment and could report that there was no vibration impact, vibrations values remained within 0.5-1cm/ minute.

A two story underground parking garage is being constructed next to Taizhou’s Guandi Temple. The design called for a retaining wall of 12-meter-long No. 4 Larssen piles, supported by 19-meter-long 700*700 H-beams.

The projects main challenges were soil conditions and zoning requirements that required special care not to damage the adjacent temple complex. The soil consisted of layers of silty clay with N-values that reached 45, which is the upper limit of a vibratory hammers working range.

The client considered using a pile press, but after analyzing the low daily production rate of this machine, decided he would not be able to complete the project in time and chose the ICE 28RF resonance free hammer for this job. The hammer’s 160t of driving force drove the beams smoothly into the hard clay. Half a month ahead of schedule and with not a single complaint from the temple the retaining wall had been completed.

Resonance free vibratory hammers use variable moment to avoid resonant vibrations during start-up and shut-down of the equipment. A second consideration is the operating frequency of the hammer; choose a machine that operates at 2000 RPM or higher for the true RF experience!