THE MISUSE OF SPT N VALUE CORRELATIONS WITH UPPER CHALK GRADES

The authors discuss the increasing use of the standard penetration test (SPT) to identify grades of chalk for foundation design, and refer to papers on middle chalk by TRM Wakeling, and on upper chalk by JP Dennehy. Dennehy is quoted as suggesting that a correlation between n value and visual determination of chalk grade in test pits should be made for each site, to facilitate chalk grade interpretation from n values at other locations and at depths not penetrated by test pits. The authors consider that there is no substitute for chalk grading by visual inspection of test pits and large diameter shafts, dewatered where necessary, and that the sole use of the SPT for foundation design in chalk should not be encouraged, bearing in mind that Dennehy had found that the SPT under-estimates the quality of the chalk. It is suggested that the increased cost of test pits and shafts for investigations would be offset by considerable savings in foundation costs. /TRRL/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 217-220
  • Serial:
    • GEOTECHNIQUE
    • Volume: 26
    • Issue Number: 1
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00138984
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Nov 3 1976 12:00AM