Job Site Reports Related to Deep FDP, Big Diameter CSP and Ring Vibrator Executed at the Limits by the Same LWN Drill Rig-Paper

Paper

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The paper describes the use of a Liebherr LRB 355 multipurpose piling rig to perform three foundation techniques near their practical operating limits: Full Displacement Piles (FDP), Cased Secant Piles (CSP), and Ring Vibrator piles.<br /><br />FDP displaces and compacts surrounding soil rather than removing it, potentially improving pile capacity while reducing spoil and vibration. The paper outlines standard and lost-bit tools, automated drilling and concrete placement, and real-time monitoring. At Dobrin, Austria, the rig installed 420 mm diameter piles to 32 m depth in soft clay with sand layers. Typical completion times were 20–30 minutes per pile, with reported production reaching 672 linear metres in a nine-hour shift.<br /><br />CSP uses cased, overlapping piles to create retaining or cutoff walls. The paper highlights the rig’s dual rotary system, which independently drives the auger and casing and is presented as an advantage in difficult ground compared with a torque converter. At St. Gallen, Switzerland, 920 mm diameter piles, up to 22 m deep, were installed in sand, gravel, moraine and areas containing large boulders. Average output was eight completed piles, or about 160 linear metres, per shift.<br /><br />The Ring Vibrator method vibrates a casing into the ground, then places reinforcement and concrete before withdrawing the casing under vibration. At Domdidier, Switzerland, three rigs installed 355.6 mm piles averaging 35 m deep, with typical cycle times of about 50 minutes.<br /><br />The authors conclude that the LRB 355’s power, automation and versatility supported high productivity and accuracy across varied ground conditions. They emphasize that equipment selection should ultimately be judged by the cost per linear metre of completed pile.

Keywords

Liebherr LRB 355

piling rig

foundation techniques

Full Displacement Piles

Cased Secant Piles

Ring Vibrator piles

dual rotary system

pile installation

ground conditions

cost per linear metre