Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Ecemiş Zeren, NurhanPublisher: search.filters.publisher.Izmir Institute of Technology

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Now showing 1 - 4 of 4
  • Master Thesis
    Effect of Fines and Ground Acceleration on Liquefaction Resistance of Silty Sand: Numerical Study
    (Izmir Institute of Technology, 2022) Tozburun, Batuhan; Ecemiş Zeren, Nurhan; 01. Izmir Institute of Technology
    Liquefaction is a phenomenon that damages structures that have not been adequately studied during the design process. While improving the performance of the buildings under dynamic loading conditions, it is essential to evaluate the liquefaction behavior of soils under the dynamic load. In this thesis, the constitutive soil model (UBCSand Model), which can simulate liquefaction, is used within the finite difference methods (FDM). First, results are compared with the laboratory test results to verify numerical liquefaction simulations. The physical and mechanical tests performed at Izmir Institute of Technology (IZTECH) are used as an input for the soil model. Then, a series of constant volume cyclic direct simple shear results (CDSS) tests performed for the same silty sands were used to verify the numerical study (Tutuncu, 2021 and Monkul, 2021). CDSS tests were performed on mixtures of clean sands and three non-plastic silts at different contents of 0%, 5%, 15%, and 35% allowing for observing the liquefaction response of silty sands of different grades (Monkul, 2021). The laboratory tests performed at Yeditepe University and Izmir Institute of Technology were combined to study the effect of fines content and relative density on cyclic liquefaction resistance of silty sands. The aim of this thesis is to perform a numerical model to evaluate the effect of fines content (FC), ground acceleration (amax) and relative density (Dr) on liquefaction resistance. The FDM model gives similar results to laboratory test results. Hence, the model can be used to assess the liquefaction with different soil models and conditions.
  • Master Thesis
    Performance of Sand Granulated Rubber Mixture for Soil Stabilization Using Discrete Element Method (dem)
    (Izmir Institute of Technology, 2022) Kadekeshova, Kuralay; Ecemiş Zeren, Nurhan; 01. Izmir Institute of Technology
    The results of a detailed analysis of the capability of numerical approach Discrete Element Method (DEM) to replicate a physical model of a sheet pile foundation in dry soil under static loads are presented in this study. Accordingly, the DEM software Particle Flow Code 2-Dimensional (ITASCA, 2019) is used to model experimental tests. Numerical model of direct shear test on clean sand and sand mixed with 10% granulated rubber has been done to calibrate the micromechanical parameters of the granular materials, such as sand and rubber particles. The particle sizes, density, interparticle friction coefficient, and contact stiffness of the discrete elements were determined and used in DEM simulations of sheet pile foundation. A total of four DEM models of the sheet pile foundation with different sand-rubber mixture backfill area were tested and analyzed in PFC2D. The loading process speed, contact stiffnesses, and porosity of the system had a significant impact on the deformation parameters of the sheet pile and lateral pressure distribution of the sand-rubber mix backfill. In this study two measurement methods were investigated. First, the measuring particles of the sheet pile particles were used, whereas the second, the measuring circles were placed behind the sheet pile foundation. The measurement circles proposed by (ITASCA, 2019) were suitable for the DEM model. Numerical outcomes showed a relative good match with the physical model. Finally, the ability of the PFC2D code as a discrete element approach in modelling of cohesionless granular material and sheet pile foundation is confirmed in this work.
  • Master Thesis
    Influence of Soil on Cone Penetration Resistance-Shear Wave Velocity Correlation
    (Izmir Institute of Technology, 2022) Örücü, Murat; Ecemiş Zeren, Nurhan; 01. Izmir Institute of Technology
    Many researchers proposed correlations between cone penetration resistance (qc) and shear wave velocity (Vs). The researchers used the datasets they obtained by performing laboratory or field tests while developing their correlations. The qc measurements were made with CPT test and Vs measurements were made with in-situ tests (SCPT, DHT, CHT). The proposed correlations were very different from each other. The existing correlations between qc and Vs are given in two ways: The soil type-dependent correlations and different correlations for different soil types. The soil type-dependent correlations were limited and also there is no change depending on fines content . Therefore, it would be useful to determine a correlation based on soil type with soils with different fines content. In this study, CPT and SCPT tests were performed in the getechnical laboratory of IZTECH to investigate the influence of soil type on qc-Vs correlation. Tests were performed on clean sand and sand - non-plastic silt mixtures having 5%, 15%, and 35% fines content at different relative densities inside the soil box. CPT profiles and Vs values were obtained to develop a relationship between Vs, and qc based on soil type index (Ic). The Ic values were found using CPT-based approaches found in the literature. A new soil type-dependent correlation to predict the Vs of soils from qc is presented in this study. The new equation was compared with existing correlations. The equation is useful to estimate Vs from CPT measurements for all soil types with different fines content.
  • Master Thesis
    Numerical Modeling of Jet Grouting Cells To Reduce Liquefaction
    (Izmir Institute of Technology, 2019) Gürbüz, Çağdaş; Ecemiş Zeren, Nurhan; 01. Izmir Institute of Technology
    The 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.