الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
The majority of high-rise buildings contain basements in their substructure. Basement walls, e.g., diaphragm walls ”skirts” or secant pile walls, are commonly used to support basement construction, which supplies lateral confinement. Moreover, the performance of shallow foundations will be highly affected by this lateral confinement.
Confining walls are successfully applied as a suitable alternate to pile, pier and surface the foundations for the offshore works, jacket structures, oil platforms and wind turbines. Confining walls guarantee overall foundation the required strengthening and efficiently increase the subgrade stiffness during the earthquake shaking occurrence. Furthermore, it is considered an efficient methodology to control the lateral spreading of the foundation soil that associated with liquefaction.
In addition, the behaviour of shallow foundations, that resting on laterally confined sand, was investigated under earthquake loads and also under static conditions using numerical modelling by PLAXIS 3D. These models were designed and validated to simulate the constructed square foundations resting on sand which is surrounded by confining walls. Varying relevant parameters were examined. Two full verifications were presented, one in purpose of the evaluation of the ultimate static bearing capacity and the other to evaluate the ultimate seismic bearing capacity.
In our obtained results, a series of charts are shown to estimate and prove the bearing capacity enhancements, which showed that the ultimate static bearing capacity can be enhanced by 2.64 ratio for 6m footing width while the improvement in the ultimate seismic bearing capacity is by 2.7 ratio. The confinement system is effective in both the seismic and static cases with the same efficiency. The confinement system is much worth construction for loose dry sand than the dense dry sand. while in the case of saturation of the dense case is much worth construction than the loose one.
With the increase of peak ground acceleration (PGA) in the dense case, The enhancement of the ultimate seismic bearing capacity ratio increases. while loose sand has less effect. The stress settlement curves showed that the confinement system reduces the impact of the earthquake on the soil subgrade including the settlement that occurs during the earthquake, by a ratio ranges from 56% to 76%.