TESTS OF BORED AND DRIVEN PILES IN CRETACEOUS MUDSTONE AT PORT ELIZABETH, SOUTH AFRICA

Three specially constructed test piles were loaded to failure to determine design values for shaft adhesion and end bearing in pile sockets in mudstone. The loading test results were related to strength tests on the rock. Cross-jacking tests in the pile sockets and crushing tests on mudstone cubes correlated well with the pile test results, indicating an ultimate end bearing capacity of nine times the undrained shear strength and an average shaft adhesion factor z=0.2. Unconfined compression tests on cylindrical core specimens appeared to underestimate, and point-load strength tests to overestimate, the mudstone strength. Subsequently some piles were driven into the same mudstone. A loading test on a test pile indicated adequate bearing capacity with much smaller depth of penetration into the mudstone than required for the bored piles. The test showed that the grouted anchor cables developed an adhesion factor z of at least 0.4. (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; Tables;
  • Pagination: p. 5-12
  • Serial:
    • GEOTECHNIQUE
    • Volume: 26
    • Issue Number: 1
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00138921
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Oct 26 1976 12:00AM