Soil-moisture retention curve changes under leachate contamination for tropical residual soils

摘要

Three samples of tropical residual soils with different degree of maturation process, were studied. Soil-moisture retention curves obtained in terms of pF (log of water column tension) were transformed from different void ratio, of each sample, in order to allow comparisons between moisture retention capacities. The results obtained showed that the contaminated soils presented a loss of moisture retention capacity, in terms of pF, up to 30%. The curve for matric suction shifted from three recognisable sections to a line with decreasing slope as the water content increases. This late shape of pF curve was reported for very fine material indicating the particle dispersion effect caused by contamination, which was also observed by the grain size tests performed with natural and contaminated soil. The osmotic suction was also observed to be effec-tive for smaller values of moisture content after contamination, when compared with natural soil.