The Austrian construction company Hilti & Jehle recently used the new LRB 355 piling and drilling rig on a jobsite in St. Gallen. The LRB 355 was equipped with the double rotary drive type DBA 300. In combination with a Liebherr concrete pump type THS 80 D-K, the piling and drilling rig was used to insert 316 piles for a secant pile wall.
Double rotary drilling combines continuous flight auger drilling with a continuous casing. Casing and auger (inside the casing) are simultaneously installed and extracted. After the final depth has been reached concrete is pumped through the auger’s hollow stem. During the extraction process the concrete exits at the lower end of casing and auger.
This foundation work is for a multi-storey office and apartment building. The piles have a diameter of 900mm and lengths of between 18 and 22m. The LRB 355 convinced on this jobsite thanks to its outstanding efficiency. Despite challenging soil conditions and remarkable drilling depths for this particular type of application, a mere 1.5 hours was required to complete one pile.
In addition to drilling with a double rotary drive, the LRB 355 can also be used for all other common drilling methods, for example, Kelly drilling, full displacement drilling or continuous flight auger drilling. Using the Kelly drilling method the LRB 355 achieves its maximum drilling depth of 60m. Other applications for which it can used include soil mixing and operation with vibrators and hydraulic hammers.