The importance of applying unsaturated soil mechanics concepts to geotechnical engineering design has been widely recognized. Soil water characteristic curve (SWCC) and hydraulic conductivity function (HCF) are vital soil properties that govern engineering behavior of unsaturated soils. In this study, a transient water release and imbibitions method (TRIM) is used to measure the SWCC and HCF under drying and wetting states, which accommodates integrated experimental and modeling techniques. The results of saturated hydraulic conductivity tests through flexible wall method are then used as input parameters for simulating experimental data. In general, the model provides a satisfactory fit to experimental data.
Soil water characteristic curves (SWCCs) and hydraulic conductivity functions (HCFs) are presented for a variety of soils that were prepared at different molding water contents and compactive efforts. The influences of dry density, molding water content, and hysteresis have been investigated. Dry density affects soil-water characteristic in terms of its air-entry value (AEV), rate of drying, and size of the hysteresis loop. The test results indicate that the SWCC and HCF obtained in terms of volumetric water content is more sensitive to the changes in dry density than molding water content. Based on cohesive soil results, some statistical relations are proposed to estimate wetting-path SWCC and HCF parameters from more easily measured drying curves. Changes in the van Genuchten's fitting parameters and residual volumetric water content are investigated for both drying and wetting conditions, with changes in the kaolin clay content. / Master of Science / Traditional soil mechanics practice has experienced considerable changes during the past few decades. Within that period, the necessity of unsaturated soil mechanics has gradually emerged and become a part of geotechnical engineering practice. Soil water characteristic curve (SWCC) and hydraulic conductivity function (HCF) are very important properties in the assessment of unsaturated soil behaviors. A transient water release and imbibitions method (TRIM) is used to investigate unsaturated soil properties of a variety of test soils under laboratory conditions. TRIM integrates a testing program and a modeling technique to measure SWCC and HCF concurrently for both drying (water release upon matric suction increase) and wetting (water imbibition upon matric suction decrease) conditions.
Compaction, which is a classical application involving unsaturated soil, has the preferred practice for improving the mechanical and hydraulic properties of a soil. The structure and fabric of compacted material is very dependent on the compacted conditions, including compactive effort and molding water content. This paper evaluates the influence of such mentioned factors on the SWCC and HCF. The test results indicate that the SWCC and HCF obtained in terms of volumetric water content is more sensitive to the changes in compactive effort than molding water content. Hysteresis phenomena, the difference in the relationship between the water content of the soil and the corresponding water potential under drying and wetting path, is investigated. Based on cohesive soil results, some statistical relations are proposed to estimate wetting-path SWCC and HCF parameters from more easily measured drying curves.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/73673 |
| Date | 23 September 2016 |
| Creators | Cuceoglu, Faik |
| Contributors | Civil and Environmental Engineering, Olgun, Celal Guney, Thompson, Theresa M., Rodriguez-Marek, Adrian |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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