اسامة مهدي عبد الحسين الحسيني

Climate change has led to more extreme weather during the last decades. Seasonally hot weather regions have experienced harsh winters. Similarly, the global warming has contributed to raising the mean summer temperature in the cold regions. Geomaterials in various engineering applications are expected to experience such changes in the weather patterns and may undergo freezing, thawing, wetting and drying processes. This thesis presents an experimental study of the one-dimensional volume change behaviour of some geomaterials under the combined influence of freeze-thaw and wet-dry cycles. Laboratory tests were carried out on three selected materials (Speswhite kaolin, Pegwell Bay soil and cement kiln dust). A custom-made test set up was used to carry out the laboratory tests that enabled performing the required tests involving freezing, thawing, drying and wetting processes. Initially saturated slurried materials and compacted materials were subjected to freezing and thawing processes to study frost heave and thaw settlement. Compacted materials were taken through several wet-dry cycles and then exposed to freezing and thawing processes to study the impact of intermittent freeze-thaw cycles on the volume change behaviour of the materials. Similarly, compacted materials were subjected to an increasing number of freeze-thawwet-dry cycles to study the combined influence of various processes on the volume change behaviour of the materials

Mishkhab city suffers from high groundwater level, which interferes with and hampers the process of any new construction of building .Another problem raised by groundwater is prevents declension water dismissal. Therefore dewatering is necessary for lowering the water table level, which was expected to be at a depth (7-10m) below ground surface. One of the most possible methods for dewatering without causing any effect to the remnants is by pumping deep well. The design considered in this study is a ringed well system surrounding the study area .A well field is containing (5) wells distributed in area about 3.8km2, according to its hydrogeologic and hydraulic characteristics. Each well is assumed to penetrate a depth of (100m), and discharged at a rate of (16l/s). The numerical model uses the finite difference technique based on the continuity hypothesis and Darcy's law. The analytical model is theoretically based on the Hantush analysis of interfering drainage wells in a leaky confined aquifer with the Superposition and Image principles. Numerical simulation is conducted with the aid of a computer program (package) called (Groundwater Modeling System, GMS) to simulate the steady and unsteady states of flow. Steady state simulation showed good agreement between the computed and observed head distribution during the calibration process. Unsteady state is observed during pumping when the well field system is operated. The outcome of such condition revealed the possibility of lowering the water table level in the Mishkhab city to the required depth after one year.

Climate change has led to more extreme weather events during the last decades. Seasonally hot weather regions have experienced harsh winters. Similarly, global warming has contributed to raising the mean summer temperature in cold regions. Geomaterials in various civil engineering applications are expected to experience changes in environmental loading conditions and may undergo freezing, thawing, wetting and drying processes accompanied by volume change which may cause severe distress to many civil engineering structures. In this paper the effects of wet-dry cycles accompanied by intermittent freeze-thaw cycles on the volume change behaviour of some materials (soils and industrial waste) were studied. Compacted samples of the materials were prepared, subjected to several wet-dry cycles and then exposed to one cycle of freeze-thaw. The patterns of wet-dry and freeze-thaw cycles were repeated. The intermittent freeze-thaw cycles destabilised the equilibrium strain that was achieved by the materials during the previous wet-dry cycles; however, a new equilibrium in terms of vertical strain was attained by the materials with an increasing number of wet-dry cycles, but with a reduced equilibrium strain. Wet-dry cycles caused an increase in the frost heave and thaw settlement for the materials studied indicating that the hydraulic conductivity increased due to exposure of the materials to increasing number of wet-dry cycles