This note describes a laboratory-scale experimental investigation undertaken to study how the separate ultimate bearing capacities of pile groups and footings (caps) are related to the resulting bearing capacities of the piled footings formed as a combination of group and cap. From the results of work described in this paper, it was concluded that three inferences are valid. In the interaction between cap, group, and soil in a piled footing, the ultimate bearing capacity of the piled footing is generally not simply an algebraic sum of the separate capacities of the cap and pile group in the freestanding state; and in sand, the piled footing has a greater capacity than this sum. Due to the interaction, sending moments are induced in the piles; and there is an increase in the friction along the shaft of each pile. The effect of this has been defined in terms of a sharing factor, and the percentage capacity change caused by the interaction is not significant. Also, the changes in both pile and cap capacities have been shown to be influenced by pile length and cap site. It is the writer's considered opinion that an instrumentation in the pile system similar to that employed in this note would adequately allow the contribution of the cap of a piled footing towards the load carrying capacity of a group to be defined as a percentage of the ultimate load, which was not previously believed possible.

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  • Accession Number: 00324517
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 15829
  • Files: TRIS
  • Created Date: May 21 1981 12:00AM