Development of a laboratory technique for obtaining soil water retention curves under external loading in conjunction with high capacity tensiometers

This paper reports the development of a testing chamber and an improved and reliable laboratory procedure capable of establishing soil water retention curves under triaxial stress conditions. The system provides the ability to take soil samples through multiple wetting–drying cycles in conjunction with measurements of suction and volumetric variables. Four drying and wetting tests were carried out on samples of glacial till and kaolin to validate the testing chamber and the associated procedures. Significant desaturation of soil samples was limited by the measurement capacity of the tensiometers. The system sustained high values of suction for a prolonged period of testing involving a sequence of drying and wetting. Suction was generated by circulating less humid air through the middle of the soil sample, which in effect generated suction gradients along the radial directions. Consequently, this had some impact on the interpretation of the volumetric variables