A Comprehensive Approach to Modeling Stress-strain Behavior of Unsaturated Soils for Geohazard Mitigation

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Abstract0301457, K. K. Muraleetharan, University of Oklahoma-Norman"A comprehensive approach to modeling stress-strain behavior of unsaturated soils for geohazard mitigation"This research project addresses geohazards and the economic design of geotechnical engineering structures associated with unsaturated soils. Swelling and shrinking unsaturated soils can result in damage to the civil engineering infrastructure, such as slope failures in residual soils caused by rainfall. Unsaturated soils are three-phase porous media consisting of the solid soil skeleton, pore gas, and pore liquid. The soil suction (pore gas pressure minus pore liquid pressure) plays a major role in the behavior of unsaturated soils.A key aspect of the proposed constitutive model is the choice of stress measures derived based on mixture theory. Another key aspect is the description of the soil-water characteristic curve (SWCC) within the framework of elastoplasticity and full coupling of it with the deformation of the soil skeleton. The coupling between the SWCC and soil deformation allows the model to describe phenomena such as shrinkage induced by reduction in water content, wetting induced collapse, and the influence of soil deformation on SWCC. Once developed, the constitutive model will be first validated in the general stress space using a series of laboratory tests performed on a compacted silty soil (Minco Silt) using triaxial and Hollow Cylinder Apparatuses (HCA) for unsaturated soil testing. Once validated at the single element level, the constitutive model will be incorporated into fully coupled 2- and 3-dimensional computer codes. These computer codes will then be used to simulate static and dynamic centrifuge model test results such as embankment settlement induced by wetting and base shaking of compacted soil embankments.The aim is to provide engineers with a capability to analyze complex 2-D and 3-D geotechnical engineering structures subjected to static and dynamic loading under a variety of soil moisture conditions. The research will be integrated into education through the participation of graduate and undergraduate students in the proposed research, as well as through course work and innovative curriculum reform projects, such as the Sooner City Project, currently underway at the University of Oklahoma.