ISSN: 1945-7545
CODEN: GTJODJ
Published Online: 10 May 2006
Page Count: 8

Development of TDR Penetrometer Through Theoretical and Laboratory Investigations: 1. Measurement of Soil Dielectric Permittivity

Lin, CP
Associate Professor and Graduate Students, Civil Engineering, National Chiao Tung University, Hsinchu,

Tang, SH
Associate Professor and Graduate Students, Civil Engineering, National Chiao Tung University, Hsinchu,

Chung, CC
Associate Professor and Graduate Students, Civil Engineering, National Chiao Tung University, Hsinchu,

(Received 10 March 2005; accepted 30 March 2006)

Abstract

To better characterize a bulk soil electrically, both the electrical conductivity and dielectric permittivity should be measured. This study developed a time domain reflectometry (TDR) penetrometer to allow simultaneous measurements of dielectric permittivity and electrical conductivity during cone penetration. A TDR penetrometer is formed by placing a multiple-conductor waveguide around a nonconducting shaft. Probe design considerations and calibration methods for measuring dielectric constant were first theoretically discussed and then evaluated through laboratory investigations. A prototype TDR penetrometer was fabricated and used to perform simulated penetration tests in a calibration chamber. The effect of penetration disturbance on dielectric constant is quantitatively reported and explained. The implications of the data that can be measured by the TDR penetrometer are also discussed.

Keywords:
dielectric permittivity, electrical conductivity, time domain reflectometry (TDR), CPT

Paper ID: GTJ14093
DOI: 10.1520/GTJ14093
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