Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effect of Stone Column Soil Improvement on Liquefaction Resistance: Field and Numerical Study(01. Izmir Institute of Technology, 2023) Budak, Merve; Ecemiş Zeren, NurhanThis study aims to understand how effective the group of stone columns is in the liquefaction mitigation of loose silty sands. Stone columns have drainage properties that help dissipate pore water pressure under cyclic loading, so the technique is used to improve the behavior of the soil under cyclic loadings, such as earthquake loading. Several analytical, experimental, and numerical studies on the liquefaction mitigation of soils by stone columns are available in the literature. Analytical methods are usually directly or indirectly based on the results of field tests that reveal the effects of stone columns. More research is needed to identify the reduction of liquefaction by stone columns, as several variables control the percentage of soil liquefaction improvement in the field. In this study, the behavior of the group of stone columns is modeled by the finite difference method (FDM), where the field test data is used as an input. The pre and post-improvement soil data used in the analyses were obtained from cone penetration tests (CPT) performed in the field before and after the construction of the stone columns using the vibroflotation (wet bottom-feed) method. Then, the earthquake loading has been applied to the unimproved and improved soil models by the stone columns. Finally, under the earthquake loading, the percentage of the liquefaction resistance increase and the settlement of the loose silty sand under structural load after stone column construction is investigated.Master Thesis Numerical Modeling of Jet Grouting Cells To Reduce Liquefaction(Izmir Institute of Technology, 2019) Gürbüz, Çağdaş; Ecemiş Zeren, NurhanThe importance of the preservation of historical and culturally important buildings is essential nowadays. While improving the performance of the buildings under dynamic loadings, it is essential to evaluate and improve the subsoil conditions. It is evident, that strengthening of the building will not provide the desired performance, if serious ground problems such as liquefaction are not eliminated during earthquake loading. In this study, liquefaction evaluation of the foundation soil of a historical building (Vali Konagi), which is in the Konak district of İzmir province, has been carried out. The simplified liquefaction assessment results based on the standard penetration tests showed that under 0.45g loading, the liquefaction problem could be observed. Therefore, soil improvement is necessary for the upper profile beneath this historical building. The jet grout cells, which is a new method were suggested as a soil improvement technique against the liquefaction of the soil below the building. The parameters related to the jet grout cells were determined, and the improved soil status was analyzed. The numerical analyses of the liquefaction investigation at unimproved and improved soil were compared by finite difference program FLAC-2D. The constitutive model (UBCSand), which can simulate liquefaction was used in the program. As a result, it is observed that; by using jet grout cells liquefaction was not triggered and deformations were kept under control.