THE VIBRATORY PILE INSTALLATION TECHNIQUE - Viking

TypeFrequencyrange[rpm]Eccentricmoment M e[lb-in.]Max F vforce[tons]Displacementamplitude S p[in.]1.) Standard20,835 517 1.26< 1,800frequency2.) High520 – 3,980 45 - 303 0.51 – 0.87> 1,800frequency3.) Variable866 – 4,670 67 - 371 0.55 – 0.671,800 - 2,400eccentricity4.) Excavator90 – 1,125 8 - 56 0.24 – 0.791,800 - 3,000mounted5.) Directional♣ ♣ ♣force ♣ 1,800 - 2,400♣ Still not commercially available, but considered as the next generation of vibratory drivers.2.3. type of vibratory drivers/extractors2.31. Standard frequencyStandard frequency are still the vast majority of vibro-units in use today since they combine afrequency range that interacts properly with most soils, and generates sufficient displacementamplitude to penetrate denser sub-surface strata’s. These units are primarily used for heavypiles and large toe resistance such as concrete and large steel pipe piles. They are at the sametime the simplest, but also the most powerful, since they are able to generate both the highestdriving force and displacement amplitude due to being equipped with the largest eccentricweights.2.3.2. High frequencyThese units are the second generation of vibrators. They were primarily developed to meet thehigher demands of reduced transmission of harmful ground vibrations to neighboring structures,which can cause undesirable settlements. This was accomplished by using higher drivingfrequencies (>30 Hz). However, these units are not as powerful as standard units, they are alsoless successful in overcoming large toe resistance compare to standard units since they do notgenerate as high displacement amplitudes.2.3.3. Variable eccentricityAlso known as resonant-free vibrators, are the third generation, and they distinguishesthemselves through their ability to start up and stop without resonant vibrations. This isaccomplished by adjusting the eccentric moment on the fly, (read adjusting the displacementamplitude on the fly). These units are considered as the “state of the art equipment” in theapplication of the vibratory installation technique to drive piles. Their applications areadvantageous in densely populated areas or city centers and for the use on vibration-sensitivejobs: i.e. near old buildings and/or hospitals with sensitive equipment (computers)…2.3.4. Excavator mountedRefers to vibro-units that are typically quick and easy to connect to the excavator boom of abackhoe with a swivel connection after that the bucket is removed. The small excavatormounted vibro-units uses normally both the existing electric circuit and hydraulic system of thebackhoe. The excavator-mounted unit is used for small or remote jobs where a cost effectivemethod is needed to vibrate a few piles. They are also ideal for low height applications andwhere a long reach is required to vibrate sheets, beams or casings.69