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Research in Geotechnical Engineering deals with the development of methodologies for improved analysis, design and construction of major infrastructure projects ranging from foundations, to tunnels and offshore structures, and for the mitigation of the impact of natural hazards such landslides and earthquakes. Also subjects of research are geoenvironmental problems related to subsurface waste containment, groundwater contamination and site remediation are also a major focus of the research, as well as problems related to resource and energy extraction, including engineered geothermal systems. Research emphasizes balance between theory and practice to provide results and methodologies that have real-world applicability and context.
Research is being carried to understand fundamental micro to macro behavior of granular soils under monotonic loading by the use of particulate modeling capabilities provided by the Discrete Element Method. Aspects of granular soil stress-strain behavior such as anisotropy, principal stress rotation and non-coaxiality as well localization, shear banding and post-localization behavior are investigated to uncover their microscopic underpinnings.
Research is being carried out to model different phenomena involving flow and transport of sand particles carried by fluids including air by coupling Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). Work includes development of new contact models that account for lubrication effects due to thin layers of fluids that are formed on the surface of particles. Example applications are flow of particles (e.g., proppants) in narrow openings (e.g., fractures) and wind-induced sand dune formation.
Research involves the evaluation of the efficiency of ground improvement techniques such as vibro-flotation in reducing the seismic-induced liquefaction potential of massive reclaimed soils in the UAE. The evaluation is based on the use of in situ tests such as the Cone Penetration Test (CPT) and field geophysical surveys in determining liquefaction of sand deposits. Periodic in situ surveys are carried out to determine the effects of soils ageing in reducing liquefaction potential.
Many soils are typically marginal in that they lack the required engineering properties for use for pavement base courses, subbase courses, subgrades, and as a foundation supporting layer under buildings and various structures. Engineers continually look for soil stabilization methods which allow the increased use of locally available materials. A newly developed soil stabilization technique was investigated through a systematic experimental study. In this technique, two non-traditional stabilizer agents, geofibers and synthetic fluid, are used to improve the bearing capacity of the soil. The effectiveness of the technique was tested on a silty sand through CBR tests. Additionaly, the performance and strength of the soil before and after improvement were evaluated through undrained-unconsolidated (UU) triaxial compression tests. Based on this initial laboratory study, it was found that the addition of geofibers and synthetic fluid can significantly increase the strength and bearing capacity of silty sands.
The cyclic stress approach is commonly used for evaluating the liquefaction potential of granular soils and therefore the majority of previous laboratory liquefaction studies have focused on stress-controlled testing. In the cyclic stress approach liquefaction potential is examined primarily in terms of shear stresses required to cause liquefaction. However, the mechanism for the occurrence of liquefaction under seismic loading conditions is the generation of excess pore water pressure, and it is well established that generation of excess pore water pressure is controlled mainly by the level of induced shear strains. Thus, a more fundamental approach to evaluate the liquefaction potential would be to use the cyclic strain procedure where the excess pore water pressure generation is examined through strain-controlled tests. This study compares the stress and strain approaches for the evaluation of liquefaction potential.
Moderate to strong shaking of saturated fine-grained soil deposits in cold regions can lead to significant excess pore water pressure generation and ultimately to liquefaction. If the pore water is fully frozen, however, no pore pressure is generated. As the ground temperature nears the freezing point (i.e., 0oC), the state of the pore water becomes partially-frozen. The response of the ground to earthquake loading in this case is completely different from either the fully frozen or the unfrozen case. This research investigates the effect of temperature on the potential to develop excess pore pressure.