Vibratory probes without jets

2 Vibratory probes without jets Purpose and principle 

Cutouts used to reduce the effective area of the probe and therefore reduce its impedance 

Research by Massarsch has led to an improved energy transmission using resonance vibro-compaction. The key features of the resonant compaction technique are the use of a specially designed compaction probe (double Y with adapted impedance) and a heavy vibrator with variable operating frequency on top of the probe. After probe insertion, the frequeney of the vibrator is adjusted to the resonance frequency of the soil layer, thereby amplifying the ground response (Massarsch, 2002). 

The results of the eompaetion are generally measured by Cone Penetration Testing (or Standard Penetration Testing) carried out before and after the compaction activities. 

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In loose to medium dense saturated sands, the strong ground vibrations in the immediate vicinity of the probe will result in an increase of pore-water pressure in the soil coliunn surroimding the vibratory probe, which is considered to lead to a state of cyclic mobility of the soil mass. Compaction with vibratory probes is hmited to granular materials only. An increase of the fines content will reduce the permeabihty and, hence, the efficiency of the compaction method. The effidenQi of vibroflotation is generally higher than the efficiency of vibratory probes (without water or air jets). 

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