1. Introduction and Background In civil engineering and geotechnical engineering, dry density of soil and water content of soil are two parameters used for construction control. They are usually measured using a radiation source with a known particle emission rate and a sensor placed to intercept particles traveling through the soil. Although 90% of the US market uses this technology, it is costly and hazardous. An alternate approach is to measure electrical properties (dielectric constant, conductivity, etc.) using time domain reflectometry (TDR). The soil parameters of interest are then calculated from the electrical parameters. Introduction and Background In civil engineering and geotechnical engineering, dry density of soil and water content of soil are two parameters used for construction control. They are usually measured using a radiation source with a known particle emission rate and a sensor placed to intercept particles traveling through the soil. Although 90% of the US market uses this technology, it is costly and hazardous. An alternate approach is to measure electrical properties (dielectric constant, conductivity, etc.) using time domain reflectometry (TDR). The soil parameters of interest are then calculated from the electrical parameters. Time Domain Reflectometry for Soil Properties Sub-team: Measurement of Average Soil Temperature Prof. V.P. Drnevich, Prof. J. V. Krogmeier ; Members: Aaron Fulton, Yuang Chen, Qiyue Zhao, Qingxuan Li, Ruohao Zou, Shakib Reza Current Topic: Perfect the technology for estimating soil temperature from measurements on spikes -Find a model to determine relationship between temperatures measured on protruding portion of spike to average temperature along the spike embedment. - Use model to determine average soil temperature from measurements before equilibrium occurs. - Develop software (Android App.) to make the calculations and report the temperature. Current Topic: Perfect the technology for estimating soil temperature from measurements on spikes -Find a model to determine relationship between temperatures measured on protruding portion of spike to average temperature along the spike embedment. - Use model to determine average soil temperature from measurements before equilibrium occurs. - Develop software (Android App.) to make the calculations and report the temperature. TDR Voltage Signal The TDR device will send a step voltage and the voltage will be reflected when a impedance mismatch occurs. A graph of voltage vs. travel length will be produced by the device to the user. Previous research has shown the soil parameters are highly correlated to the shape of the trace, and has developed an algorithm to fit the trace and estimate the soil parameters. TDR Voltage Signal The TDR device will send a step voltage and the voltage will be reflected when a impedance mismatch occurs. A graph of voltage vs. travel length will be produced by the device to the user. Previous research has shown the soil parameters are highly correlated to the shape of the trace, and has developed an algorithm to fit the trace and estimate the soil parameters. V1 VinVin VfVf Equipment For Measurement Pipe Clamp Thermocouple NI Thermocouple Measurement Data Logger USB Equipment For Measurement Pipe Clamp Thermocouple NI Thermocouple Measurement Data Logger USB