Abstract: Soil suction measurement is crucial for the stability assessment of geotechnical engineering, real-time and accurate measurement of suction changes in soil from saturated to dry state has always been a hot topic and challenge in the field of unsaturated soil mechanics. Dew point water potential technique is a novel measurement method of soil suction. This paper detailly introduces the working principle of the PSYPRO dew point water potential meter and the significance of the required debugging parameters, and combines the calibration test and the evaporation test to give the optimal time parameter setting recommendations for the PSYPRO dew point water potential meter to measure different soil suction intervals. In this paper, the PST-55 psychrometer was firstly calibrated with different concentrations of NaCl solutions and the correction coefficient was obtained, and then the laboratory soil evaporation test was carried out, the PST-55 psychrometer and ML3 soil moisture sensor were used to measure the drying process. The changes in soil suction and water content verified the feasibility and accuracy of dew point water potential technique for real-time continuous monitoring of soil suction. 

Key words: soil suction, measurement method, soil-water characteristic curve, dew point-water potential, correction factor;
optimal parameter