Schmertmann has found the flat dilatometer very practical to use in conjunction with the Dutch static cone penetration test (CPT). The same 10-ton thrust hydraulic equipment and rods used to insert the static cone easily adapt to the dilatometer. A dilatometer sounding can be made at a rate of about 10 min/m, when taking the A and B dilatometer reading at 0.2-m. (8-in.) depth intervals. With the 10-ton CPT equipment the dilatometer can be pushed from the surface through soils with standard penetration (SPT) resistance blowcount of about N=30 or less to reach a layer of interest. Stronger surface soils would probably require preboring to permit dilatometer access. The dilatometer test also offers the unique potential of permitting a rapid determination of a soil's consolidation behavior, essentially within minutes rather than the days or weeks required for undisturbed sampling and laboratory consolidation testing. In his closure, Marchetti emphasizes that the dilatometer test belongs to the class of penetration tests and not to that of pressuremeter tests. The dilatometer, with its flat-plate shape, and with its sharp cutting edge, should modify the original stress-strain state of the in situ soil to a lesser degree than penetration tests such as the CPT and SPT. This reduces the amount of extrapolation required to estimate the undisturbed in situ behavior and thereby should improve the quality of the correlations with engineering design parameters. He notes, however, that the test does overpredict both K and 0 and OCR in days exhibiting marked aging or cementation effects. The c sub u values predicted are generally lower than field vane values by a ratio in the range of 0.7-1.0 but are comparable after reduction using the Bjerrum correction.

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Filing Info

  • Accession Number: 00335545
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 16287 Proceeding
  • Files: TRIS
  • Created Date: Oct 28 1981 12:00AM