Evaluation of measurement sensitivity and design improvement for time domain reflectometry penetrometers. Issue 4 (26th April 2015)

• Record Type: Journal Article
• Authors: Zhan, Tony Liang‐tong; Mu, Qing‐yi; Chen, Yun‐min; Ke, Han
• Is Part Of: Water resources research. Volume 51:Issue 4(2015:Apr.)
• Page Start: 2994
• Page End: 3006
• Publication Date: 2015-04-26
• Subjects: TDR penetrometer -- measurement sensitivity -- design improvement; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2014WR016341
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: The time domain reflectometry (TDR) penetrometer, which can measure both the apparent dielectric permittivity and the bulk electrical conductivity of soils, is an important tool for the site investigation of contaminated land. This paper presents a theoretical method for evaluating the measurement sensitivity and an improved design of the TDR penetrometer. The sensitivity evaluation method is based on a spatial weighting analysis of the electromagnetic field using a seepage analysis software. This method is used to quantify the measurement sensitivity for the three types of TDR penetrometers reported in literature as well as guide the design improvement of the TDR penetrometer. The improved design includes the use of semicircle‐shaped conductors and the optimization of the conductor diameter. The measurement sensitivity to the targeted medium for the improved TDR penetrometer is evaluated to be greater than those of the three types of TDR penetrometers reported in literature. The performance of the improved TDR penetrometer was demonstrated by conducting an experimental calibration of the probe and penetration tests in a chamber containing a silty soil column. The experimental results demonstrate that the measurements from the improved TDR penetrometer are able to capture the variation in the water content profiles as well as the leachate contaminated soil. Key Points: Measurement sensitivity of TDR penetrometers