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Back stability analysis, in-lab testing, and field tests may all be used to assess the behavior of stability of slopes. Each of these approaches has benefits and drawbacks compared to one another. Amongst these approaches, laboratory modeling stands out with its ability to prepare identical samples, keep external conditions under control, and measure deformations precisely. In this study, laboratory-based slope models at 1(Horizontal)/1(Vertical), 2/3, and 1/3 angles including the effects of precipitation and external loading were created. The results of these models were compared with those of the Plaxis 2D software. First, models were built using highly permeable cohesionless coarse-grained soils, and mixtures containing high plasticity clay (bentonite) at different rates were then prepared to investigate the effect of fine-grained soils on stability. Laboratory tests such as sieve analysis, specific gravity, consistency limits, Standard Proctor, and direct shear were used to assess the geotechnical index properties of soils. Incremental surcharge loads were placed on the slope models and surface deformations, and local and general collapses under the effect of precipitation were observed. Laboratory model results highlighted that the fines content had a non-negligible effect on stability. When the slope behaviors were examined, it was observed that the models with a 1/3 slope had more severe local fractures and collapses. The stability of the slope is negatively affected when bentonite content in soil mixtures rises. The results of Plaxis 2D analysis are compatible with those of laboratory model tests and the safety factors obtained from Plaxis 2D range from 0.98 to 11.4.

Highly plastic expansive clays swell or shrink due to change in moisture content and they often have very low bearing capacity. Construction of engineering structures particularly pavements and lightweight buildings on problematic soils such as highly plastic expansive clays may create severe structural problems due to poor engineering properties of that kind of soil. This study focused on the influence of fly ash on strength properties of highly expansive clays which are problematic soils due to their undesirable engineering characteristics such as high plasticity index, liquid limit, swelling and shrinkage characteristics, and low bearing capacity. Atterberg’s limit tests and hydrometer tests were conducted to obtain consistency limits and grain-size distribution of the highly plastic expansive clay. Standard proctor tests for clay samples with different fly ash contents such as 10%, 15%, and 20% were performed to determine maximum dry densities and optimum water contents of the mixtures of clay and fly ash. The clay and fly ash mixtures were prepared at optimum water content and maximum dry density for unconfined compression strength (UCS) and California Bearing Ratio (CBR) tests. Effects of fly0ash content on the strength characteristics of a highly plastic expansive clay were investigated through unconfined compression and CBR tests. The experiment results showed that fly0ash is a promising additive to enhance strength characteristics of highly plastic expansive clays. An approximately 66% increase in UCS and CBR values was observed with the addition of 20% fly ash into the clay mixture in weight.

Belirli dane boyutlarina gore siniflandirilan zeminler dogada genellikle cesitli oranlarda karisim halinde bulunmaktadir. Bu calisma kapsaminda 3 farkli kompozisyonda hazirlanmis kil - cakil numunelerinin kayma mukavemeti ozellikleri buyuk olcekli direk kesme deneyleriyle incelenmistir. Cakil turunun, dane boyutunun, seklinin ve puruzlulugunun kayma mukavemeti uzerindeki etkisinin incelenmesi amaciyla cesitli dane dagilimina sahip kirmatas ve dere cakillari kaolin kiliyle belirli kompozisyonlarda karistirilarak numuneler hazirlanmis, doygun durumda deneyleri yapilmistir. Deneyler neticesinde kirmatas iceren ayni kompozisyondaki iki numuneden, iri dane dagilimli numunenin %10 oraninda daha buyuk icsel surtunme acisina sahip oldugu belirlenmistir. Ayni kompozisyon ve dane dagilimina sahip iki numuneden kirmatas iceren numunenin, dere cakili iceren numuneden %16 daha buyuk icsel surtunme acisina sahip oldugu belirlenmistir

Many methods are used to improve the engineering properties of the soils. While the some of the developed methods cannot produce an effective solution, some of them are not economical for practical solution. In this study, permeability and shear strength behaviors of natural kaolin, bentonite and sand mixtures have been investigated in the presence of three different biopolymers (xanthan gum, chitosan and chitin) and different concentrations (0.25-0.50-0.75 and 1%). The results have shown that, the xanthan gum and chitosan addition decreased the permeability coefficient almost 30 hold. While the biopolymer effect on shear strength behavior is investigated, 1% xanthan gum and chitosan concentration addition provided 15-10% increase in angle of internal friction. The obtained test results have shown that, biopolymers can be used in dams and landfills at impermeable clay liner applications.

Gelişen dünya nüfusunaparalel olarak kentsel katı atık miktarı her geçen gün artmaktadır. Mühendisliközellikleri iyi tanımlanmamış katı atıklar ile yapılan kontrolsüz depolamalarsonucu oluşan göçmeler can güvenliğini tehlikeye atmakta ve büyük ekonomik kayıplaraneden olmaktadır. Bu çalışmada laboratuvar koşullarında belirlikompozisyonlarda sentetik olarak üretilmiş ve doğal atık depolama sahasındanalınmış taze ve yıllanmış kentsel katı atık (KKA) numunelerinin doğal suiçeriği, organik madde miktarı, özgül ağırlık ve pH değerleri belirlenmiştir.Doğal ve sentetik KKA numunelerinin kayma mukavemeti parametreleri büyükölçekli direk kesme cihazıyla belirlenmiştir. Elde edilen mühendislikparametreleri kullanılarak mevcut ve tasarlanmış KKA şevlerinin duraylılıkanalizleri yapılarak statik ve dinamik koşullar altında güvenlik sayılarıbelirlenmiştir. Çalışmadan elde edilen Türkiye KKA kompozisyonuna aitmühendislik parametreleri ve duraylılık analizleri sonuçları kullanılarak,Türkiye’de daha güvenli ve ekonomik KKA depolama sahalarının tasarımıyapılabilir., In parallel withthe developing world population, the amount of urban solid waste increases dayby day. Uncontrolled storage of solid wastes with poorlydefined engineering properties can result in a risk of life safety and seriouseconomic loss. In this study, natural water content, organic matter content,specific gravity and pH values of the synthetic waste (with pre-determinedcompositions) and natural waste samples were investigated in laboratoryconditions. Shear strength parameters of the synthetic and natural municipalsolid waste (MSW) samples were determined by using a large scale direct sheartest system. The slope stability analyses were conducted for present slopes atstatic and dynamic conditions and the factor of safety values were obtained.The obtained Turkey MSW composition engineering parameters can be used in thedesign of safe and economical MSW storage areas in Turkey.

Investigation of aging effect is important due to examination of long-term influence of contaminants on the landfill liners. The effect of Na + and Ca 2+ 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, Ca 2+ 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 Ca 2+ 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 O' values of kaolin and bentonite samples decreased by time.