Capillary rise determination using simplified image analysis method

Abstract

Capillary rise underestimation can reduce the long-term performance of civil engineering projects, especially those concerned with ground moisture, such as basements, roads, dams, and soil barrier liners. According to Peck et al. [1], the grain shape constant in empirical capillary rise estimation relationships varies between 10 and 50 mm2 and can be difficult to assume. Furthermore, the measurement of capillary rise in laboratory settings is also quite challenging because it occurs in the transition zone between saturated and unsaturated soils. This study focused on the application of the simplified image analysis method (SIAM) to capillary rise determination for the assessment of the grain shape constant as proposed by Peck et al. [1]. SIAM is a non-intrusive, non-destructive laboratory technique used to measure the temporal and spatial distribution of water saturation in whole domains. In this study, six one-dimensional tests were conducted using a 35 mm × 35 mm × 550 mm column to simulate capillary rise at fixed groundwater levels. The results show that values smaller than 25 mm2 should be used for coarser sand, whereas values greater than 25 mm2 should be used for finer sand. This study demonstrates that SIAM can be further utilized in studies of unsaturated soil, especially to assess soil saturation changes.