Publication Abstract

Proceedings - Fifth International Conference & Exhibition on Piling and Deep Foundations, 1994, Bruges, Belgium, (DFI)

Slender small diameter piles with very high bearing capacity
A.L. Garassino & M. Nesti

In an existing very crowded foundation area of a thermal Power Station many new additional foundations had to be built on piles. Due to the lack of operative space, a small diameter drilled pile type with the injected bottom section was selected as suitable solution in spite of the reduced dimensions of the machines. High bearing capacity was needed with design working load of 1000 kN in compression and 50 kN as horizontal load. A very stiff steel pipe reinforcement was adopted and the micropiles construction was carried out under controlled conditions in order to achieve the best results that technology can supply. The design was carried out starting from experimental data of an instrumented drilled shaft. The design assumptions and the goodness of the selected construction procedure was tested on a trial test pile up to 2500 kN load in compression and a second trial pile was tested to 1200 kN in tension. Other tests were then carried out on other piles of the foundations to 2000 kN load. The test piles and 2 furtherly tested piles were instrumented and allowed us to collect useful information of the pile0-soil interaction: the results are described in the paper. Micropiles cast in place in cased holes and in holes supported by bentonite mud did not show appreciable differences as general behavior but some influence has been detected on the mechanism of developing shaft resistance.

 article #841; publication #36 (IC-1994)