+7 (967) 282-70-79
e-mail: info@bkdelta.ru

Cased Kelly Piles


According to this technology, casing is advanced by rotary head thorough the casing clamps and simultaneously jacked. Casing consists of a series of rigidly connected sections. As the casing is advanced, the soil inside it is removed by an auger and then a new section is added.  Auger is fixed to the end of the Kelly-bar that expands as the borehole is deepened. 

Process starts with the advancing drilling of the borehole with casing  with a reinforced tip (core bit). The core bit serves for drilling of soil  and concrete of primary piles for construction of secant bored piles. The casing in inserted into the soil with a rotary head or the casing oscillator to a  depth of 1,5-2,0 m. Further by using a telescopic  Kelly bar  with a short auger the casing is cleared from soil. 

Operations on borehole drilling and soil extraction are repeated every 1.5-2.0 m of casing penetration. When the  project depth drilling tool  is extracted from the casing, drilling cuttings are removed  from the hole, reinforcement cage is installed and fixed and the borehole is filled with  tremie method. 

Construction sequence

  1. Advancement of inventory pipe   through rotary head and casing oscillator.Forming the borehole with casing by advanced drilling . 
  2. Insertion of reinforcement cage. Installation of  tremic pipe. Filling the borehole with concrete.
  3. Extraction of casing.
  4. Completed bored pile (formation of pile cap )



To construct piles with this technique  Delta Drilling Company uses  Soilmec SR-60, SR-65 and  SR-80C  drilling rigs, which can be optionally  equipped with the casing oscillator.


Efficiency of Use

 Although this techinique has low productivity it  is used due to following:

  • possibility of pile construction  in different types of soil;
  • absence of dynamic and vibrational impacts on soil during the installation of protective  constructions near existing buildings;
  • modern equipment of the drilling rig allowing to control drilling process, drilling and extract boulders;  
  • in the course of drilling direct control of compliance of the characteristics of a soil put in the project is exercised;
  • besides, it allows to avoid  their vypor in a well at the expense of a soil plug and an excessive pressure in a well by means of water;
  • reliable protection of borehole walls against a collapse;
  • filling of a well through a tremic pipe that excludes formation of pins and defects of pile shafts;  
  • high quality of filling a well with concrete;
  • possibility of pile base formation which allows to use the bearing ability of a pile.