Permeability determination from on-the-fly Piezocone sounding

Derek Elsworth, Dae Sung Lee

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Solutions are developed for the steady, partially drained, fluid pressure field that develops around a moving penetrometer. These include rigorous solution for a point volumetric dislocation moving in a saturated elastic soil and an approximate solution for a pseudostatic, finite-volume, penetrometer moving in a nondilatant soil. These solutions provide a consistent framework for viewing the penetration process, and enable the nondimensional sounding indices of normalized tip resistance Qt, friction factor Fr, and pore pressure ratio Bq, to be straightforwardly linked to important material properties of the soil, most notably that of permeability, via a nondimensional permeability KD. This factor KD is inversely proportional to penetration rate, and is directly proportional to both permeability and vertical in situ effective stress. Simple relationships are developed to link these nondimensional sounding metrics, via KD. Most notably, the resulting simple relationship KD= 1/ BqQt enables soil permeability to be determined from peak fluid pressures recorded on-the-fly. Importantly, these parameterizations enable plots of Bq-Qt, Fr-Qt, and Bq-Fr to be contoured for KD, and hence for permeability. These plots define the relative superiority of using Bq-Qt data pairs over those for Fr-Qt and Bq-Fr, in defining permeability. Similarly, the feasible range of permeabilities that may be recovered from peak pressure data are defined; permeabilities must be sufficiently high that penetration is not undrained, and sufficiently low that the resulting pressure response is not null (fully drained). These limits are a natural product of the analysis and represent permeabilities in the range 10-4 10-7 m/s. The utility of these characterizations is confirmed with data from two locations where cone soundings are correlated with independently estimated permeabilities. Journal of Geotechnical and Geoenvironmental Engineering

Original languageEnglish (US)
Pages (from-to)643-653
Number of pages11
JournalJournal of Geotechnical and Geoenvironmental Engineering
Volume131
Issue number5
DOIs
StatePublished - May 1 2005

All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology
  • Environmental Science(all)

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