This paper investigates the long-term measurement of negative (tensile) pore-water pressures in soils by using high capacity tensiometers (HCTs). Seven different HCT prototypes were designed and manufactured by using different porous filters, pressure transducers, water reservoirs and protective casings. The ability of these prototypes to record negative pore-water pressures over long times was initially assessed by a series of measurements on small clay samples equalised at different suction levels. These tests were followed by two larger scale experiments in which four HCT prototypes were simultaneously installed inside a lysimeter filled with a sandy soil alongside two standard dielectric permittivity sensors measuring suction and water content, respectively. In one experiment, the soil was left to dry until all four HCTs cavitated while, in another test, the soil was allowed to dry up to an intermediate level of suction before triggering a rainfall, after which the soil was left to dry again until all four HCTs cavitated. In each lysimeter experiment, the readings of the HCTs were reasonably consistent, which suggests that sensor design has little effect on the accuracy of measurements. These experiments also indicated that HCTs are more accurate and exhibit a faster response than standard dielectric permittivity sensors. Moreover, the HCTs incorporating a small water reservoir showed a greater ability to sustain suction over long period of time without cavitating.

本文研究了使用高容量张力计（HCT）长期测量土壤中负（张性）孔隙水压力的方法。通过使用不同的多孔过滤器，压力传感器，水箱和保护性外壳，设计和制造了七个不同的HCT原型。这些原型长期记录负孔隙水压力的能力最初是通过对在不同吸力水平下均等的小粘土样品进行一系列测量来评估的。在这些测试之后，进行了两个较大规模的实验，其中，将四个HCT原型同时安装在装有沙土的测渗仪内，并同时安装两个分别测量吸力和水含量的标准介电常数传感器。在一项实验中，将土壤干燥直至所有四个HCT空化，在另一项测试中，在引发降雨之前让土壤干燥至中等水平的吸力，然后再使土壤干燥直至所有四个HCT空化。在每个测渗仪实验中，HCT的读数都相当一致，这表明传感器设计对测量精度几乎没有影响。这些实验还表明，与标准介电常数传感器相比，HCT更精确且响应速度更快。此外，装有小水箱的HCT表现出更大的能力，可以长时间保持吸力而不会出现气蚀现象。HCT的读数是合理一致的，这表明传感器设计对测量的准确性影响很小。这些实验还表明，与标准介电常数传感器相比，HCT更精确且响应速度更快。此外，装有小水箱的HCT表现出更大的能力，可以长时间保持吸力而不会发生气蚀。HCT的读数是合理一致的，这表明传感器设计对测量的准确性影响很小。这些实验还表明，与标准介电常数传感器相比，HCT更精确且响应速度更快。此外，装有小水箱的HCT表现出更大的能力，可以长时间保持吸力而不会发生气蚀。