Master Degree / Yüksek Lisans Tezleri

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

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Author: search.filters.author.Egeli, İsfendiyarSubject: search.filters.subject.Slopes (Soil mechanics)--Stability

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  • Master Thesis
    Laboratory Tests To Study Stability Mechanism of Rainfall Infiltrated Unsaturated Fine-Grained Soil Slopes Developing Into Shallow Landslides and Their Hydraulic Properties
    (Izmir Institute of Technology, 2013) Şahin, Yavuz; Egeli, İsfendiyar; Egeli, İsfendiyar; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    This study consists of two parts. In the first part, saturated soils wetting band infiltration theories and the most widely used in the world by Lumb, 1975 and Pradel and Raad, 1993 compares theoretical predictions were compared with observed results which gave poor correlations. Results showed that both theories grossly underestimated wetting-band thicknesses. Because above mentioned two theories result in constant values, instead of giving values changing as functions of time. These theories need corrections, which indicate need for further studies. In the second part, hydraulic properties were determined (water-retention, hydraulic-conductivity) of locally obtained 3 undisturbed soils near saturation with a new Hyprop testing technique using the evaporation method. As the Unified Soil Classification System (USCS) does not distinguish inorganic clay colloids by size (size <0,001 mm or 1000 nanometers), Lazer Diffraction Method was used. Results have shown that under zero overall stress; Matric suction does not stay constant, but increases with time up to a maximum point and then decreases, whereas time to reach maximum matric suction increases with decreasing plasticity index (PI) and colloid content (c). While maximum matric suction increases with PI and c, hydraulic conductivity and volumetric water content decreases with increasing matric suction. Also, hydraulic conductivity at maximum matric suction decreases with increasing PI and c.
  • Master Thesis
    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.