Abstract: Ever more attention has been paid to geotechnical problems induced by wetting and drying of soils recently. Suction up to 80 kPa, measured by tensometers, has been used for analyzing geotechnical problems such as slope instability during wetting and drying. However, existing tensometer generally has a long response time and is easy to cavitate since it has a large volume of water reservoir and complicated internal structure. These drawbacks affect the sensitivity and reliability of a conventional tensometer seriously. In order to overcome these shortcomings, a newly developed fabricated tensometer is introduced. This type of new tensometer with fabricated structure has a simple internal structure and a small volume of water reservoir. At the same time, a drainage hole is introduced to prevent large excess pore water pressure during the process of reassembling. More importantly, its saturation procedure is simple and efficient since the high air-entry ceramic disc and pore pressure transducer of this new tensometer can be disassembled for saturation separately and effectively. After the saturation of the high air-entry ceramic disc and pore pressure transducer, these key components are reassembled together as a tensometer ready for use. As compared with a conventional tensometer, the sensitivity and reliability of this new tensometer are justified. The results of calibration test show that the sensitivity of the new tensometer increases by 90% by comparing with the conventional tensometer. In the case of measuring the pore water pressure of -80 kPa, the equilibrium time required for this new tensometer is only 1.5 minite, about 10% of that for the conventional tensiometer. Moreover, the reliability of the new tensometer is better than that of the conventional tensometer. The measurement error of the conventional tensiometer is about 30%, when measuring the pore water pressure of -80 kPa. Subjected to the same conditions, the new tensometer shows a measurement error of only 0.7%.

Key words: suction measurement, tensometer, sensitivity, reliability