Volume 15, Issue 3 (September 1992)
The Application of Time Domain Reflectometry in Geotechnical Instrumentation
The performance of road pavements and earth structures is dependent on the moisture regime experienced during their service life. One of the practical challenges in understanding moisture regimes in earth structures has been to continuously monitor moisture fluctuations in a nondestructive and reasonably accurate way. The time domain reflectometry (TDR) device shows considerable promise in overcoming many of the drawbacks of traditional techniques. The TDR measures the volumetric moisture content of the soil via a buried sensor (probe). Probes can be buried and monitored remotely, and an immediate result can be obtained.
This paper outlines the principles of the TDR device and its mode of operation. Brief details are presented on the experience gained using the TDR on embankment installations, which are currently being monitored. Scope exists for its wider application in the general field of geotechnical instrumentation.