A method for detecting the surface moisture content of expansive soil based on time-domain reflection technology

The surface moisture content of expansive soil does not decrease linearly, making it difficult to confirm the range of changes in the surface moisture content of expansive soil based solely on waveform signals, which affects the stability and accuracy of moisture content detection. A method for detecting the surface moisture content of expansive soil based on time-domain reflection technology has been designed. Analyze the factors affecting the moisture content of expansive soil, fix the main physical indicators of expansive soil, use the TRIME-T3 TDR instrument from Germany as the main equipment, obtain the time-domain reflected microwave signal for measuring the surface moisture content of expansive soil, and introduce the bipolar pulse intermittent voltage source measurement method to measure the dielectric constant of soil, excite the time-domain reflected waveform signal, weaken the polarization effect at the position of impedance discontinuity, and calculate the surface moisture content of expansive soil. The experimental results show that after introducing the bipolar pulse intermittent voltage source measurement method, the time-domain reflection results are more stable, with a smaller fluctuation range, and can effectively analyze the soil conductivity values. The resistance change rate gradually increases with the increase of moisture content. Satisfied the demand for detecting the surface moisture content of expansive soil, and guided the construction process of foundation reinforcement engineering with more stable and accurate moisture content detection results.