| Abstract: |
The basic premise of this work is the dynamic soil-structure interaction (DSSI)between an underground structure and the supporting soil, which has a significant effecton the response of the structure and the resulting localization of stresses and settlementsduring seismic events. This thesis focuses on simulating the static and dynamic analysisof diaphragm walls embedded through soil media. The Automatic Dynamic IncrementalNonlinear Analysis (ADINA) software is used to model the structure and the surroundingsoil.The soil surrounding the structure is modeled as Mohr-coulomb material whereasthe diaphragms walls, raft foundation, and the multi-storey building component aremodeled as an elastic material simulating the reinforced concrete. Many parameters areconsidered including different types of soil, such as; medium stiff clay and dense sandsoil. Other structural parameters like the diaphragm width, embedment depth, and raftfoundation thickness. The presence of ground anchors system support is also consideredin the study. The loading pattern is divided into four phases; first stage is concerned withstatic or consolidation phase in which the soil is allowed to consolidate under its ownweight. The second stage is includes modeling the diaphragm wall construction, groundanchor construction, excavation, then constructing the raft foundation, followed by themulti-storey building. The third stage is the main stage, in which the dynamic analysis isperformed by applying the seismic event. The final stage is another static phase in whichthe pore water pressures generated during the dynamic analysis are allowed to dissipate,and the settlements and stresses within the soil domain are also computed. The Northridgeearthquake record which occurred in San Fernando Valley with a Richter Magnitude of6.7 is used in the dynamic analysis.It was found that under static loading pattern, changes in diaphragm walls widths orincreasing the embedment depth of the diaphragm walls through the soil media in case ofclay soil could not achieve stability for the diaphragm walls, necessitating the use ofground anchors system to achieve stability. On the other hand, when the diaphragm wallsconstructed in sand soil media theoretical analysis showed stability of the diaphragmunder normal loading conditions, but practically ground anchors should be used toaccount for any unexpected loads that may act during construction. Under the earthquakeevent, the pore water pressure is increased suddenly while the effective vertical stressdecreases. This phenomenon is more pronounced in sand soil than the clay soil media.High stresses took place in the soil under the diaphragm walls, behind the groundanchors, and under the raft foundation.
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