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Modelling Vertically Loaded Pile Groups by Considering Pile-Soil Interactions
(2023) İşbuğa, Volkan; İşbuğa, Volkan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The aim of the study presented in this thesis is to create a model that takes into account the interaction between piles for the analysis of pile groups embedded in a linear elastic medium. This research builds upon prior work by Vallabhan and Mustafa (1996) introduced a single pile model and the pile-soil-pile interaction model proposed by İşbuğa (2023). The model has undergone further development to encompass the entire spectrum of pile groups regardless of how many piles it has and what kind of layout it has. This comprehensive model addresses two distinct scenarios: one involving a free-head pile group and another featuring a pile group that has a rigid pile cap. In the context of a free-head pile group, single piles within the group show different displacements due to load and interactions. On the other hand, in the case of a rigid pile cap, the piles must have equal displacements because of the rigid nature of the pile cap. Two different algorithms have been developed for both of these scenarios, and these algorithms have been implemented using the Python programming language. The model has been used to analyze various pile groups, and the analysis results were compared with previous studies and finite element method solutions. In addition to comparing the results, the computation times of the models proposed by this study and those of the finite element method were also compared.
Seismic Liquefaction: 1-G Model Testing System and Shake Table Tests
(Izmir Institute of Technology, 2013) Kahraman, İrem; Ecemiş, Nurhan; Ecemiş, Nurhan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Soil liquefaction is a crucial, interesting and complex seismic problem. Previous earthquake records and computational modelings have given general information about liquefaction, but many questions, such as; effects of silt content on liquefaction phenomena have not been clearly answered yet. In this study, liquefaction phenomena in sands and silty sands were simulated by a large scale 1-g laminar box system. Three shake table tests were performed, where each test consisted of four shakes to analyze the initial-liquefaction and re-liquefaction phenomena. Instrumentations were used during shake table tests to measure laminate, soil response and settlement of ground. The soil deposit was prepared with different fines content using hydraulic filling method. Piezocone penetration tests (CPTu) were conducted, before and after each shake to determine the relative density of the soil model. Following results were found; Silty sands were found to possess more liquefaction resistance than uniform fine sands. Soils with rounded shapes were more susceptible to liquefaction, than angular grained soils. Required time to trigger liquefaction increased with fines content and depth of the soil sedimentation. Liquefaction resistance of each tested sand decreased from 1st to the 2nd shaking, despite increase in relative density. Relative density values increased with each shake. Despite the increase in relative density, liquefaction resistance decreased. Relative density values have decreased, when fines content increased, but despite decreased in relative density, liquefaction resistance increased. Ground settlement values after the shaking was more than during the shaking. Ground settlement values have increased with fines content of the soil model.
An Experimental and Analytical Study of Various Soil Slopes in Laboratory Conditions
(Izmir Institute of Technology, 2009) Pulat, Hasan Fırat; Egeli, İsfendiyar; Egeli, İsfendiyar; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Slope stability is a significant subject of geotechnical engineering. Slope failures triggered by rainfall are causing considerable damage and loss of life every year throughout the world. Especially at dry seasons when the rainfall is scarce, the ground can develop considerable amount of suction and this improves the shear strength of the soil. In rainy season, when rainfall infiltrates into ground, suction decreases, while the shear strength also reduces, which may lead to slope instability. One of the principle objectives of this study is to represent the development of soil-water interaction modeling system (SWIMS) at IYTE. Using this system; effects of 3 different parameters, such as: initial water content, soil density, slope angle on modelling unsaturated slope stability were studied. Moreover, effects of infiltration on slope stability in shallow landslides, where it is assumed that the ground water tables are located at significant depths, were examined.In this thesis study, 12 main slope model experiments were completed in laboratory conditions, using Soil-Water Interaction Modelling System (SWIMS) by varying 3 different parameters. Result of studies shows that slope angle is the most important parameter affecting slope stability. Furthermore, parameters such as; soil density, degree of relative compaction of soil and initial water content affects slope stability, while these parameters also affect slope surface erosion and infiltration depths. In addition to experimental studies conducted in laboratory conditions with the 12 main slope model experiments, slope stability analyses to find FOS were performed by using Plaxis V9 (2D) finite element program (FEM), which uses shear strength reduction (SSR) technique and infiltration analyses using the Plaxflow module to model the rainwater infiltration into slope soil were performed. The FEM analyses show conforming results with the actual observations made using the tested soil model in laboratory conditions.

Master Degree / Yüksek Lisans Tezleri

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