Spatial variability in soils: High resolution assessment with electrical needle probe

Gye Chun Cho*, Jong Sub Lee, J. Carlos Santamarina

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


The global response of a soil is affected by spatial as well as temporal scales. An electrical needle-size probe is developed to effectively assess one-dimensional spatial variability. The probe is designed for laboratory specimens (needle diameter 1.2-2.2 mm), and it can be scaled for field applications. Design considerations include the tip shape, insertion disturbance, electrochemical effects, corrosion, operating frequency, and electrical resonance. Two calibration methods are presented to determine local soil permittivity and resistivity from the measured complex impedance; the simplified calibration procedure is based on resistance measurements only. The local electrical parameters permit one to infer the soil porosity and the electrolyte conductivity. The attainable spatial resolution depends on the needle diameter; submillimetric resolution is typically achieved in laboratory applications. Reconstituted sand specimens and undisturbed clayey specimens are tested to explore the resolution potential of this probe. The electrical needle probe clearly detects the spatial variability that results from different specimen preparation methods in sands and soil layering from natural formation histories such as those in varved clays.

Original languageEnglish (US)
Pages (from-to)843-850
Number of pages8
JournalJournal of Geotechnical and Geoenvironmental Engineering
Issue number8
StatePublished - Aug 2004
Externally publishedYes

ASJC Scopus subject areas

  • General Environmental Science
  • Geotechnical Engineering and Engineering Geology


Dive into the research topics of 'Spatial variability in soils: High resolution assessment with electrical needle probe'. Together they form a unique fingerprint.

Cite this