Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 8Citation - Scopus: 8Estimation Groundwater Total Recharge and Discharge Using Gis-Integrated Water Level Fluctuation Method: a Case Study From the Alasehir Alluvial Aquifer Western Anatolia, Turkey(Springer Verlag, 2020) Şimşek, Celalettin; Demirkesen, Ali Can; Baba, Alper; Kumanlıoğlu, Ahmet; Durukan, Seda; Aksoy, Niyazi; Tayfur, GökmenThe estimation of groundwater recharge is an essential process for hydrogeological study. Realistic determination approach is crucial for assessing groundwater potential in an aquifer system and estimating of groundwater levels and/or changes in dry periods. Based on these matters, we employ a GIS-integrated groundwater level fluctuation method to determine the groundwater recharge for a hydrological period in the Alasehir alluvial aquifer (W. Anatolia). The method basically takes into account both increasing and decreasing of the groundwater levels due to the recharge and discharge mechanisms in the aquifer. In this study, 16 pumping and monitoring wells were drilled with a total depth of 1300 m, and water level data loggers were installed into the monitoring wells to determine the groundwater level changes. The spatial distribution of the monthly groundwater level change map was multiplied by the aquifer storage distribution map and then the accurate water volume is calculated by using the 3-D spatial analysis. According to our evaluation in the aquifer, positive volume change of the groundwater is 187 hm(3) in a year, which is considered as a recharge value of groundwater. It is concluded that the GIS-integrated water table fluctuation method gave rise to estimate the total recharge amount of the groundwater in the Alasehir aquifer. The total groundwater recharge indicates that total inflow in the aquifer from precipitation, leakage from surface water and irrigation waters. It can be stated that the recharge estimation of groundwater in a surficial aquifer, like the Alasehir aquifer, is fairly easy using the GIS-integrated water table fluctuation method.Article Citation - WoS: 16Citation - Scopus: 20Groundwater Recharge Estimation Using Hydrus 1d Model in Alaşehir Sub-Basin of Gediz Basin in Turkey(Springer Verlag, 2019) Tonkul, Serhat; Baba, Alper; Şimşek, Celalettin; Durukan, Seda; Demirkesen, Ali Can; Tayfur, GökmenGediz Basin, located in the western part of Turkey constituting 2% land of the country, has an important groundwater potential in the area. Alasehir sub-basin, located in the southeast of the Gediz Basin and subject to the extensive withdrawal for the irrigation, constitutes the study area. Natural recharge to the sub-basin due to precipitation is numerically investigated in this study. For this purpose, 25 research wells, whose depths range from 20 to 50 m, were drilled to observe the recharge and collect the necessary field data for the numerical model. Meteorological data were collected from 3 weather stations installed in the study area. The numerical model HYDRUS was calibrated using the field water content data. Soil characterization was done on the core samples; the aquifer characterization was performed, and the alluvial aquifer recharge due to precipitation was calculated. As a result, the computed recharge value ranges from 21.78 to 68.52 mm, with an average value of 43.09 mm. According to the numerical model, this amount of recharge corresponds to 10% of the amount of annual rainfall.Article Citation - WoS: 22Citation - Scopus: 27Micromechanical Modeling of Intrinsic and Specimen Size Effects in Microforming(Springer Verlag, 2018) Yalçınkaya, Tuncay; Özdemir, İzzet; Simonovski, IgorSize effect is a crucial phenomenon in the microforming processes of metallic alloys involving only limited amount of grains. At this scale intrinsic size effect arises due to the size of the grains and the specimen/statistical size effect occurs due to the number of grains where the properties of individual grains become decisive on the mechanical behavior of the material. This paper deals with the micromechanical modeling of the size dependent plastic response of polycrystalline metallic materials at micron scale through a strain gradient crystal plasticity framework. The model is implemented into a Finite Element software as a coupled implicit user element subroutine where the plastic slip and displacement fields are taken as global variables. Uniaxial tensile tests are conducted for microstructures having different number of grains with random orientations in plane strain setting. The influence of the grain size and number on both local and macroscopic behavior of the material is investigated. The attention is focussed on the effect of the grain boundary conditions, deformation rate and the grain size on the mechanical behavior of micron sized specimens. The model is intrinsically capable of capturing both experimentally observed phenomena thanks to the incorporated internal length scale and the crystallographic orientation definition of each grain.Conference Object Citation - WoS: 1Development of a Proper Mix-Design for Impact Loading of Deflection Hardening Hybrid Fiber Reinforced Concrete(Springer Verlag, 2018) Alami, Muhammad Musa; Erdem, Tahir Kemal; Yardımcı, Mert Yücel; Aydın, SerdarThis study aims to develop a low-cost Hybrid Fiber Reinforced Concrete (HyFRC) that exhibits deflection hardening behavior under bending and has high energy absorption capacity under impact loading by determining proper combination of steel and polyvinyl alcohol (PVA) fibers. More than forty mixtures were prepared including two mixtures of conventional concrete, six mixtures of Engineered Cementitious Composites (ECC), and thirty-six mixtures of HyFRC. The design parameters were chosen as fly ash to cement ratio (1.2, 1.7 and 2.2), steel fiber type and amount (0.5%, 0.75%, and 1.25% by volume), PVA fiber amount (0.25% and 0.50% by volume), and maximum aggregate size (Dmax) of 8 mm and 16 mm. Several tests were carried out on fresh and hardened specimens such as bending, compression, and low-velocity flexural impact loading. Based on the results, it is found that the mixture with 0.75% steel fiber and 0.25% PVA showed the best performance for the aim of the study.Article Citation - WoS: 2Citation - Scopus: 4Removal of Metals and Metalloids From Acidic Mining Lake (aml) Using Olive Oil Solid Waste (osw)(Springer Verlag, 2019) İlay, Remzi; Baba, Alper; Kavdır, YaseminThe acidic mining lakes have low pH values and high metal and metalloid concentrations. In this study, the ability of low-cost olive oil solid waste (OSW) to remove Al, As, Cd, Fe, B and Ti ions from aqueous solutions in short term has been evaluated. Adsorption capacities (mg g−1) of OSW (1:5–1:10 w/v) were 764.06–411.75 for Al, 0.26 for As, 0.07–0.14 for Cd, 2181.5–2406.5 for Fe, 23.70–82.50 for B and 0.12–0.0.34 for Ti. OSW addition increased acidic mine water (AMW) pH from 2.41 to 3.2 with 1:5 and from 2.41 to 2.7 to 1:10 mixing ratio, respectively, after 10 min. The best gradual decrease has been observed with different ratio of OSW applications on B and Ti concentrations. OSW adsorbs 32.41% and 62.68% of B at the ratio of 1:5 and 1:10 and 55.29% and 83.04% of Ti at the ratio of 1:5 and 1:10 (OSW:AMW) mixtures, respectively. The results show that OSW has great potential for metal removal from acidic mine water.Book Part Citation - Scopus: 1Hybrid Control of a 3-D Structure by Using Semi-Active Dampers(Springer Verlag, 2014) Turan, GürsoyA base isolated three storey 3-D building is semi-actively controlled not to exceed the maximum allowable base displacement. Large displacements are likely to cause failure in the isolation system, and hence, failure in the superstructure is expected. If a base isolated structure is positioned next to a very long fault line, such as the North Anatolian Fault, the structure will mostly undergo far field type excitations. Near field effects will be seen less occasionally, but design considerations should be made to account for both types of excitations. In case of nearby seismic action, the isolated building should be smart enough to modify its isolation impedance to resist against large ground displacement and velocities. For this study, an isolated three storey building model together with four dampers, which are all placed at the base level, is considered. The dampers have controllable orifices (damping coefficients) and the magnitudes of these damping coefficients are assigned by using a linear quadratic regulator (LQR). During an earthquake excitation, the storey displacements and velocities are used as feedback in the calculation of the optimal control force that is producible by viscous dampers, at each time step. This force, however, is applied only at times when critical displacements and/or velocities occur. The performance of the set of controllers is presented via time simulations of the system for three recorded earthquakes. In addition, these records are time shifted five folds to see the effect of near field action. The results indicate that the control effectively reduces the maximum displacements of the isolation system, while maintaining a reasonable isolation to the superstructure.Article Citation - WoS: 14Citation - Scopus: 2Climate Change Mitigation With Renewable Energy: Geothermal(Springer Verlag, 2011) Baba, AlperOn a global scale, there is increasing evidence that climate is changing and of a discernible human influence. Many of scientists are confident that if current emissions of greenhouse gases continue, the world will be warmer, sea levels will rise and regional climate patterns will change. According to some scientist, global temperatures are expected to rise faster over the next century than over any time during the last 10,000 years. From this token, geothermal energy is now considered to be one of the most important alternative energy sources to minimize climate change. Geothermal technologies for power generation or direct use operate with little or no greenhouse gas emissions. Geothermal energy is generally accepted as being an environmentally-friendly energy source, particularly when compared to fossil fuel energy sources. Geothermal resources have long been used for direct heat extraction for district urban heating, industrial processing, domestic water and space heating, leisure and balneotherapy applications. Geothermal energy is used in more than 80 countries for direct heat application and 24 countries for power generation. Re-injection of fluids maintains a constant pressure in the reservoir, thus increasing the field's life and reducing concerns about environmental impacts. Geothermal energy has several significant characteristics that make it suitable for climate change mitigation.Article Modeling Water Stress Effect on Soil Salinity(Springer Verlag, 2011) Tayfur, GökmenAs it is widely known the earth is experiencing a climate change. The primary effect of this change is the increase trend in global temperature. This, in turn, results in increased number of events in flooding, and drought in different parts of the world. A secondary effect is the change in water and soil salinity. A considerable portion of the cultivated land in the world is affected by salinity, limiting productivity potential. About 20 million ha of total 230 million ha of irrigated land in the world are salt affected. The climate change is expected to worsen this situation. This study explores the water stress effect on soil salinity. For this purpose, a model is developed to simulate salt transport in a layered soil column. The soil salinity transport model development involves two parts: (1) modeling salt movement through sail layers due to runoff, percolation, and lateral subsurface flow, and (2) modeling dissolution and precipitation of gypsum which acts as sink or source for salts in soil. The model is calibrated and validated with measured data. The soil is irrigated under optimal and water stress irrigation conditions. The major model parameters affecting the soil salinity are found to be wilting point, field capacity, hydraulic conductivity, initial soil salinity, and soil gypsum concentration. The results have revealed that water stress results in high concentration of salt accumulation in soil columns.Article Citation - WoS: 18Citation - Scopus: 22The Health Risk Associated With Chronic Diseases in Villages With High Arsenic Levels in Drinking Water Supplies(Springer Verlag, 2017) Gündüz, Orhan; Bakar, Coşkun; Şimşek, Celalettin; Baba, Alper; Elçi, Alper; Gürleyük, Hakan; Mutlu, Merdiye; Çakır, AyşeThis study is intended to compare and assess the distribution and possible causes of current chronic diseases in villages with high arsenic levels in drinking water supplies. It is a cross-sectional epidemiological research that analyzes the frequency and underlying risk factors of chronic diseases in villages with varying levels of arsenic exposure through drinking water. Sample space of study included 1003 individuals, 614 of whom were from villages with high arsenic levels in drinking water and remaining 389 were from two control villages with below-limit arsenic levels in drinking water. While nutritional habits and living environments of two groups were similar, cigarette smoking and alcohol use were higher in villages with low arsenic levels. Mini mental state examination test results in 60+ age group were lower in villages with high arsenic levels. Although no statistically significant differences were detected in chronic disease occurrence between the groups, the number of cases was higher in villages with higher percentage of cigarette smoking and alcohol use. Moreover, cases of lung, colon, and stomach cancers were higher in villages with high arsenic levels in drinking water supplies.Article Citation - WoS: 17Citation - Scopus: 21The Use of Neural Networks for the Prediction of Cone Penetration Resistance of Silty Sands(Springer Verlag, 2017) Erzin, Yusuf; Ecemiş, NurhanIn this study, an artificial neural network (ANN) model was developed to predict the cone penetration resistance of silty sands. To achieve this, the data sets reported by Ecemis and Karaman, including the results of three high-quality field tests, namely piezocone penetration test, pore pressure dissipation tests, and direct push permeability tests performed at 20 different locations on the northern coast of the Izmir Gulf in Turkey, have been used in the development of the ANN model. The ANN model consisted of three input parameters (relative density, fines content, and horizontal coefficient of consolidation) and a single output parameter (normalized cone penetration resistance). The results obtained from the ANN model were compared with those obtained from the field tests. It is found that the ANN model is efficient in determining the cone penetration resistance of silty sands and yields cone penetration resistance values that are very close to those obtained from the field tests. Additionally, several performance indices such as the determination coefficient, variance account for, mean absolute error, root mean square error, and scaled percent error were computed to examine the performance of the ANN model developed. The performance level attained in the ANN model shows that the ANN model developed in this study can be employed for predicting cone penetration of silty sands quite efficiently.