Publication Abstract

Proceedings - Fourth International Conference - Piling and Deep Foundations, 1991, Stresa, Italy, (DFI)

Behavior of large diameter bored piles in overconsolidated cohesive soils
V. Cotecchia & L. Monterisi Institute of Engineering Geology and Geotechnics, Bari University, Italy

The results of loading tests on bored piles with 1.20 m and 1.50 m diameters and 24 m and 32 m in length are analyzed respectively. The piles were bored into a medium plasticity overconsolidated marly-clayey formation. One of the piles was instrumented with strain gauge deformation wires. The load was applied by hydraulic jack against a steel frame held down by four anchor piles having the same diameter. The applied load was measured by load cells; the settlement of the pile top was observed by optical device and by three dial gauges fixed to an independent steel frame. The load-settlement diagram suggests an elastic behavior of the pile soil complex within the range of stress values reached. The maximum test loading value turns out to be remarkable lower than the ultimate load calculated by means of present methods. Deformation values made it possible to plot the distribution curve of the axial load. The distribution of shear stresses was then calculated along the shaft by means of classical methods and the applied load displacement curve along the same shaft was plotted. Diagram values indicate that the applied load was mainly transferred through lateral skin friction. Eventually, the experimentally induced maximum lateral adherence values were compared with the ones obtained by means of the present design criteria.

 article #516; publication #37 (IC-1991-IT)