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Abstract Soil water content and dry density are important parameters in geotechnical engineering. Conventional measuring methods are time consuming，destructive，and automatic multipoint real-time monitoring is not achieved. On the basis of electromagnetic theory and time domain reflectometry(TDR) method，the effects of TDR sensor type，material and size on the accuracy of the measurement are systematically analyzed. A new TDR sensor with advantages of good integrity，reliable performance and low cost is designed for the disadvantages of existing commercial sensors. Then，the practicability of TDR sensor is tested and verified by specially designed large-scale model test. The results show that the new sensor can be used to measure in-situ soil gravimetric water content and dry density accurately and quickly. Furthermore，the long-term real-time monitoring of soil water content and dry density at different depths can also be implemented by it. The new sensor is an efficient tool in quality control during construction and safety monitoring in the service period of geotechnical engineering projects.
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Received: 30 July 2010
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2011, Vol. 30 
