ESTIMATES OF SHAFT AND END LOADS IN PILES IN CHALK USING STRAIN GAUGE INSTRUMENTATION

Since the end of 1973, eight test piles in chalk have been instrumented in order to determine detailed information on their behaviour under test. Of these eight, four were bored and four were driven, and the distributions of load with depth have been determined for the first time in chalk in A similar manner to that previously used in sands and clays. The driven piles were instrumented with strain gauges only, while the bored piles were instrumented with strain gauges and rod extensometers. All were tested under maintained loads to at least twice the working load, and some were subjected to cyclic loadings. From the detailed strain profiles now available, together with information on the cross-sectional area and on the modulus from strain results over a control length, it has been possible to determine load variations with depth. By considering depth increments and integrating strain profiles it has been possible to determine relationships between the loads mobilized both in shaft load transfer and in end-bearing, and the differential movements between pile and soil which produced them. Graphs are produced giving quantitative relationships calculated from the above mentioned tests for three sites in the upper and middle chalk at various depths, and some of the implications on design procedure are discussed. Comparison between bored and driven piles shows much higher creep strains in the higher stressed conditions of the latter, and the effects of this and other aspects of the load profiles are discussed. (a). This paper forms part of the second geotechnique symposium in print: "piles in weak rock". For the covering abstract of the symposium see IRRD abstract no.220250. /TRRL/

Media Info

  • Features: Figures; References;
  • Pagination: p. 133-147
  • Serial:
    • GEOTECHNIQUE
    • Volume: 26
    • Issue Number: 1
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00138924
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Oct 26 1976 12:00AM