Capillary rise in eluvium-deluvial gravelly soil

The height of capillary water rise and the associated moisture distribution influence the permeability and strength of capillary zone soils. Accurate determination of the capillary rise height and moisture profile is therefore essential for evaluating the stability of slopes composed of eluvium-deluvial gravelly soil. To investigate the capillary rise behavior in such gravelly soils, considering their particle size characteristics, an existing capillary water rise testing apparatus was improved based on its particle size characteristics. The improved testing apparatus was then utilized to conduct capillary water rise height measurements and moisture content tests at different height sections of 14 gravelly soil columns under two dry densities and seven fine/coarse particle content ratios. Based on the experimental results, the influence of density and fine/coarse particle content ratio on capillary water rise was analyzed, and a function for predicting capillary water rise height using fine particle content in gravelly soil was proposed. The results reveal that the capillary rise height in eluvium-deluvial gravelly soil increases with the fine particle content and dry density. The test findings further indicate that eluvium-deluvial gravelly soil with higher fine particle content and greater dry density presents significantly elevated stable volumetric moisture content in the soil columns. The stable height of capillary water rise in all tested gravelly soil columns did not exceed 1.0 m, indicating that the influence of the stable groundwater level on the moisture content of the overlying eluvium-deluvial gravelly soil is limited in the study area. This study can provide a valuable insight for slope stability assessment, geological risk evaluation, and early warning systems in mountainous areas with eluvium-deluvial gravelly soil.