Comparison between methods of soil saturation on determination of the soil water characteristic curve of cohesive soils

Abstract

In this study, the effect of saturation methods on the SWCC (soil-water characteristic curve) values of the soil (matric suction) was investigated. The objectives of this study are making a comparison between the soil saturation methods and the effect of soil saturation methods on the SWCC. The study also makes a comparison between determining of SWCC using (Whatman 42) filter paper method and Mp6 sensor device. The methods that were studied are the saturation by adding water to the top surface of the sample and sample saturation through the capillary by adding water to the bottom of the samples, and the third used method of saturation is by compacting the soil with a predetermined water content to give a certain degree of saturation. The laboratory specimens were used to evaluate the effect of different methods of soil saturation and methods of sample preparation, on the obtained SWCC, also to compare the results of SWCC that were obtained by using MP6 sensor with the filter paper method. The saturation methods adopted and investigated in this study are the top surface water adding, capillary water raise, and compaction of the soil with predefined water content. The wetting and drying of SWCC have been obtained to all the used saturation methods, by using both the MP6 sensor and the filter paper method. The results showed that the samples that were saturated by the capillary method had higher soil water characteristic SWCC values than those saturated by adding water at the top of the sample surface or those prepared by compacting the soil with a predetermined water content. The comparison between the three methods of saturation reveals that the capillary rise saturation gives a higher value than the top surface water top and the variable water content method for both wetting and drying SWCC cases. Also, the top surface water top gives higher magnitude of SWCC than variable water content method.