Browsing by Author "Pulat H.F."
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Item Mechanism and modelling of shallow soil slope stability during high intensity and short duration rainfall(Sharif University of Technology, 2011) Egeli I.; Pulat H.F.Shallow landslides in nearly saturated uncohesive to slightly cohesive soils are triggered by high intensity, short duration rainfall which infiltrates into soil and changes intergranular friction and effective stresses. For this, the especially developed SoilWater Interaction Modelling System (SWIMS) was used with CL-ML type soils. For simplicity, rainfall intensity and duration were kept constant. Results showed that (1) All 35° slopes were failed by translational failure. For the other (15°,25°) slopes, no failures were observed; (2) For all slopes, FOS increased with increasing compaction degree and decreased with increasing slope angle; (3) Other parameters, such as soil density, porosity, saturation degree, water contents, and water permeability may also affect shear strength/slope stability, especially for low degrees of saturation (S<95%), compared to high degrees of saturation (S=,>95%). (4) A correlation of SWIMS tests observed that average wetting band depths ( hobser), with the calculated wetting band depths from the Lump Equation (hLE), were poor, as hobser values were much higher than hLE values. Differences increased for very low degrees of saturation (S), compared to S>95%. This meant that the Lump equation underestimated wetting band depths. Further, if the Lump equation is still considered valid, this would imply either water-permeability increases, porosity decreases or both occur towards full saturation; a process where the last possibility is the most probable occurrence. © 2012 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved.Item Compaction behavior of synthetic and natural MSW samples in different compositions(2013) Pulat H.F.; Yukselen-Aksoy Y.Compaction is the one of the most important stages of the storage process in landfills. Well-compacted municipal solid waste (MSW) occupies less volume than an uncompacted MSW sample of the same weight and provides a safer storage area. The composition of MSW changes in between countries and even cities. For that reason, for effective compaction, the composition effect should be investigated. In this study, effects of composition, degradation and energy on the compaction behavior of artificially-prepared and natural fresh and aged MSW samples were determined. Artificial samples were prepared in representative different compositions Europe (E-1), Turkey (T-1) and the USA (U-1) to examine the effect of the composition. In addition to the synthetic MSW samples, natural MSW samples were obtained from the municipal landfill area of Manisa, Turkey. The standard Proctor test results have shown that the highest maximum dry unit weight was observed with the U-1 composition, which has the lowest organic content and the highest metal content. The degradation effect was investigated on the natural samples. The degraded MSW sample (3-4 years) has significantly higher maximum dry unit weight than the fresh natural MSW sample because of its low organic content. According to the results of this study, with respect to the composition effect, the percentage of organic waste is the most important factor on the compaction behavior of MSWs. As paper, organic and plastic contents increase in the MSW composition the γdry-max value decreases and wopt increases. The ash content does it reversely, as such that any increase in γdry-max decreases the wopt value of the MSW. © 2013 The Author(s).Item Composition and degradation effects on the compaction characteristics of municipal solid wastes(Taylor and Francis - Balkema, 2013) Pulat H.F.; Yukselen-Aksoy Y.Inordertoprotect environment and human health, MSW mustbestored regularlyand confidently. For safe and economic MSW storage, significant processes are initialized (dumping, spread out, burying and compacting). Compaction is the one of the most important stages of the storage process. Well compacted MSW renders less volume than the same weighted uncompacted MSW. Furthermore, well compaction provides safer storage area. In this study, the effect of composition, degradation, and energy on the compaction behavior of artificially prepared and natural fresh and aged MSW samples were determined. The standard and modified proctor tests were performed on the fresh and aged samples. Artificial samples were prepared in different compositions to examine the effect of composition. In addition to the synthetic MSW samples, natural MSW samples were provided from municipal landfill area of Manisa city. © 2013 Taylor & Francis Group.Item Composition and degradation effects on the compaction characteristics of municipal solid wastes(CRC Press, 2013) Pulat H.F.; Yukselen-Aksoy Y.In order to protect environment and human health, MSW must be stored regularly and confidently. For safe and economic MSW storage, significant processes are initialized (dumping, spread out, burying and compacting). Compaction is the one of the most important stages of the storage process. Well compacted MSW renders less volume than the same weighted uncompacted MSW. Furthermore, well compaction provides safer storage area. In this study, the effect of composition, degradation, and energy on the compaction behavior of artificially prepared and natural fresh and aged MSW samples were determined. The standard and modified proctor tests were performed on the fresh and aged samples. Artificial samples were prepared in different compositions to examine the effect of composition. In addition to the synthetic MSW samples, natural MSW samples were provided from municipal landfill area of Manisa city. © 2013 Taylor & Francis Group, London.Item Developing cation exchange capacity and soil index properties relationships using a neuro-fuzzy approach(Springer Verlag, 2014) Pulat H.F.; Tayfur G.; Yukselen-Aksoy Y.Artificial intelligence methods are employed to predict cation exchange capacity (CEC) from five different soil index properties, namely specific surface area (SSA), liquid limit, plasticity index, activity (ACT), and clay fraction (CF). Artificial neural networks (ANNs) analyses were first employed to determine the most related index parameters with cation exchange capacity. For this purpose, 40 datasets were employed to train the network and 10 datasets were used to test it. The ANN analyses were conducted with 15 different input vector combinations using same datasets. As a result of this investigation, the ANN analyses revealed that SSA and ACT are the most effective parameters on the CEC. Next, based upon these most effective input parameters, the fuzzy logic (FL) model was developed for the CEC. In the developed FL model, triangular membership functions were employed for both the input (SSA and ACT) variables and the output variable (CEC). A total of nine Mamdani fuzzy rules were deduced from the datasets, used for the training of the ANN model. Minimization (min) inferencing, maximum (max) composition, and centroid defuzzification methods are employed for the constructed FL model. The developed FL model was then tested against the remaining datasets, which were also used for testing the ANN model. The prediction results are satisfactory with a determination coefficient, R2 = 0.94 and mean absolute error, (MAE) = 7.1. © 2014, Springer-Verlag Berlin Heidelberg.Item The effect of soil mineralogy and pore fluid chemistry on the suction and swelling behavior of soils(Springer Verlag, 2014) Pulat H.F.; Yukselen-Aksoy Y.; Egeli İ.Soil suction is one of the most important parameters for describing the moisture condition and engineering behavior of unsaturated soils. Therefore, changes in suction behavior of soils in the presence of saline waters are important for engineered barriers. The aim of this study was to determine the change in suction and swelling behavior of soils, which were exposed to salt solutions (NaCl, CaCl2, natural seawater) with respect to distilled water. The three soil samples were gathered with different mineralogy and plasticity characteristics and tested for determining matric and total suction values and for obtaining free swelling characteristics in the presence of salt solutions. The bentonitic soil sample had the highest total suction value in the presence of seawater. Kaolinitic and zeolitic soil samples had the highest total suction values in the presence of NaCl solution. The highest modified free swell index value of the samples was obtained in the presence of NaCl solution for all the soil samples. No relationship was found between the total suction, matric suction and the modified free swell index value of the tested soils. © 2013, Springer-Verlag Berlin Heidelberg.Item Suction characteristics of compacted zeolite-bentonite and sand-bentonite mixtures(2014) Durukan S.; Pulat H.F.; Yukselen-Aksoy Y.Soil suction is one of the most important parameters describing soil moisture conditions for unsaturated soils used in landfill liners. However, few studies have been conducted on the suction characteristics of compacted zeolite-bentonite mixtures (ZBMs) and sand-bentonite mixtures (SBMs), which are proposed for use as liner materials. Nevertheless, zeolite is known for its microporous skeleton containing cages and tunnels and it has a great physical affiliation to water uptake. Zeolite and bentonite, in a mixture, are thought to be in competition for water uptake and this may alter the distribution of water content for each soil in the mixture. The present study investigated the suction properties of compacted ZBMs and SBMs for varying mixing ratios and compaction water contents. The soil suction measurement technique chosen was the filter-paper method. The suction characteristics of powdered, granular, and block zeolites, as well as 0, 10, and 20% bentonite in ZBMs and SBMs were measured and compared with each other. Contaminated compacted ZBMs are compared with those of uncontaminated compacted ones at the optimum water content for the 10% and 20% mixtures. The results show that suction capacity of zeolite increases with grain size. As bentonite content increases, both matric and total suction increase for both mixtures. ZBMs have higher matric suction values than SBMs, but not total suction values. Contaminated total suction values are found to be higher than those of uncontaminated samples due to an increase in dissolved ion concentration. © The Author(s) 2014.Item Pore fluid chemistry and aging effects on swelling, shear strength, and pore size distribution behavior of soils(American Society of Civil Engineers (ASCE), 2014) Çakar E.; Pulat H.F.; Aksoy Y.Y.Investigation of aging effect is important due to examination of long-term influence of contaminants on the landfill liners. The effect of Na+ and Ca2+ ions on the engineering behavior of soils were examined and the aging effect on engineering properties of kaolin and bentonite samples in the presence of ions were observed. The pore size distribution, swelling and shear strength parameters were determined under the same conditions after approximately 60, 190 (shear strength), and 250 (swelling) days. There is no difference at the swell index values of kaolin in the presence of DI water and 0.5 M NaCl. However, Ca2+ ions decreased the swell index of the kaolin sample. In the presence of Na+ ions, there is no difference at the swell index values of the bentonite sample. However, in the presence of Ca2+ ions, swell index decreased from 0.035 to 0.029. During aging, the reverse effect occurs at bentonite sample when compared with kaolin sample. It is expected that, as aging progresses, bonds between particles increase; therefore, the swell index of the soils decrease. However, the results of this study have shown that this is not true for bentonitic samples. When the results of 0 day, 60 and 190 days samples were compared, the \xQ' values of kaolin and bentonite samples decreased by time. © 2014 American Society of Civil Engineers.Item Influence of Seawater on the Suction and Swelling Behavior of Clayey Soils(Taylor and Francis Ltd., 2015) Pulat H.F.; Yukselen-Aksoy Y.The present study examines the suction characteristics and swelling behavior of clayey soils when exposed to natural seawater with respect to distilled water. The effects of saline waters on the engineering behavior of soils need to be determined since the salinity of the pore fluid of soils near coastal areas increases continuously. Six clayey soil samples with different mineralogy and characteristics were gathered and tested to determine the suction and swelling characteristics in the presence of natural seawater and distilled water. The results show that the total suction values of the samples are higher in the presence of seawater than in distilled water. The samples with high swelling potential have lower matric suction values than nonswelling soils. Moreover, in contrast to swelling-type soils, the matric suction values of the nonswelling soils remain similar in the presence both distilled water and seawater. The modified free swell index (MFSI) of the samples is well correlated with the liquid limit (LL), plasticity index (PI), and cation exchange capacity (CEC) in distilled water. However, coefficients of determination decreased in the presence of seawater. Also, there is no significant correlation existing between total and matric suction values and the MFSI values of the samples. © 2015, Copyright © Taylor & Francis Group, LLC.