Evaluation of Different Laboratory Procedures for Determining Suction-Water Content Relationship of Cohesionless Geomaterials

摘要

The determination of suction-water content relationship (SWR) is of prime importance in unsaturated soil mechanics. When such a relationship is obtained from continuous drying or wetting process of the same soil sample, it is termed as water retention characteristic curve (WRCC). The relationship obtained from suction measurement of remolded soil samples with different water content is termed as spot SWR (SSWR). Most of the reported studies use drying WRCC (DWRCC) because of the relative ease of its measurement as compared to wetting WRCC (WWRCC). There are not many studies that critically compare measured DWRCC, WWRCC, and SSWR of soils. Such a comparison would help to understand the differences in WRCC attributable to hysteresis and limitations of spot measurements, if any. A simple procedure similar to the field wetting process is discussed in this paper for developing DWRCC and WWRCC on the same soil sample, one after the other. WRCCs and SSWRs of three cohesionless soils are not unique for the range of suction measured in this study. The implication of such nonuniqueness is further investigated by comparing unsaturated soil hydraulic conductivity function estimated based on WRCCs and SSWRs.