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Öğe BEARING CAPACITY and BULGING BEHAVIOR of GEOGRID ENCASED STONE COLUMNS(2016) Demir, Ahmet; Sarıcı, TalhaAbstract: Son yıllarda yumuşak zeminlerin iyileştirilmesi için kullanılan taş kolonun kullanımını artırmak için geogrid kaplama kullanılmaktadır. Bu çalışmada, geogrid kaplamanın, yumuşak zemin yatağı içerisindeki taş kolonun performansına olan etkisi araştırılmıştır. Geogrid kaplı ve geogridsiz taş kolonun davranışını belirlemek için deneysel ve numerik çalışmalar gerçekleştirilmiştir. Deneysel çalışma için küçük ölçekli laboratuvar testleri gerçekleştirilmiştir. Ayrıca, geoteknik mühendisliğinde iki boyutlu deformasyon ve stabilite analizleri için tasarlanmış sonlu elemanlar programı olan PLAXIS numerik çalışmalar için kullanılmıştır. Numerik çalışmalar gerçekleştirilmeden önce deneysel çalışmaların ve numerik analizlerin uyumluluğu kontrol edilmiştir. Uyum elde edildikten sonra taş kolonda geogridin rijitliğinin, geogrid kaplama boyunun ve yanal genişleme gibi farklı parametrelerin etkisi numerik çalışmalar ile araştırılmıştır. Ek olarak grup kolonlar da incelenmiştir. Bu çalışmanın sonuncu olarak, geogridin kaplama boyu ve rijitliği geogrid kaplı taş kolonun yük taşıma kapasitesini ve genişleme davranışını önemli ölçüde etkilemektedir.Öğe Bearing capacity of footing supported by geogrid encased stone columns on soft soil(Techno-Press, 2017) Demir, Ahmet; Sarici, TalhaThe stone columns are increasingly being used as a soil improvement method for supporting a wide variety of structures (such as road embankment, buildings, storage tanks etc.) especially built on soft soil. Soil improvement by the stone column method overcomes the settlement problem and low stability. Nevertheless, stone column in very soft soils may not be functional due to insufficient lateral confinement. The required lateral confinement can be overcome by encasing the stone column with a suitable geosynthetic. Encasement of stone columns with geogrid is one of the ideal forms of improving the performance of stone columns. This paper presents the results of a series of experimental tests and numerical analysis to investigate the behavior of stone columns with and without geogrid encasement in soft clay deposits. A total of six small scale laboratory tests were carried out using circular footing with diameters of 0.05 m and 0.1 m. In addition, a well-known available software program called PLAXIS was used to numerical analysis, which was validated by the experimental tests. After good validation, detailed of parametric studies were performed. Different parameters such as bearing capacity of stone columns with and without geogrid encasement, stiffness of geogrid encasement, depth of encasement from ground level, diameter of stone columns, internal friction angle of crushed stone and lateral bulging of stone columns were analyzed. As a result of this study, stone column method can be used in the improvement of soft ground and clear development in the bearing capacity of the stone column occurs due to geogrid encasement. Moreover, the bearing capacity is effected from the diameter of the stone column, the angle of internal friction, rigidity of the encasement, and depth of encasement. Lateral bulging is minimized by geogrid encasement and effected from geogrid rigidity, depth of encasement and diameter of the stone column.Öğe Comparison of bipolarity features between art students and other university students(2019) Kocamer Sahin, Sengul; Demir, Ahmet; Elboga, Gulcin; Altindag, Abdurrahman; Dogan, IlkayAim: There is a common belief that creativity and artistic talent/creativity are related to psychopathology. Mood disorders are more prominent in studies about relations between creativity and psychopathology. Also patients may be more productive during mania and hypomania periods of bipolar mood disorder. Considering these data, the purpose of this study was to investigate whether there is a predisposition to bipolar disorder in people with artistic creativity. Materials and Methods: A total of 157 students were selected randomly from the Art department and 157 from different departments including Faculties of Law, Science and Literature and Education. Art students had proven their artistic competence by two stage examination. Groups were compared based on mood disorder questionnaire (MDQ) and bipolarity predisposition factors. SPSS 22.0 was used for statistical analyses. Chi-square analysis was used to compare case-control groups according to demographic characteristics.Results: There were no significant differences between the groups in terms of age, sex, education, smoking, marital status, family history of psychiatric disorder. The number of psychiatric admissions were higher in the students of art (p=0.026). Alcohol-substance use was higher among students of Art (p=0.001). The MDQ scale result was 50.3% positive for Art students and 26.8% positive for students from different departments. MDQ scale, the predisposition of bipolar disorder was found to be significantly higher in Art students.Conclusion: The high prevalence of bipolarity features with MDQ scale in art students supports the relationship between artistic talent / creativity and bipolar disorder.Öğe Evaluating of geosynthetics reinforced road base with plate loading tests(Pamukkale Univ, 2021) Ok, Bahadir; Demir, Ahmet; Sarici, Talha; Ovali, MesutThe use of geosynthetics as reinforcement for the base layer of flexible pavement systems has grown steadily over the past thirty years. Although geosynthetic reinforcements can lead to improved pavement performance, the specific conditions or mechanisms that govern the reinforcement are unclear, largely remaining unidentified and unmeasured. In this study, the assessment of the effect of geogrids on the roads that is reinforced granular fill layer over soft clay soil, section's ability to support before and after traffic loads were investigated using plate loading tests in situ. The results of the field tests show that geosynthetic reinforcement as is an effective method in reducing deformation and repairing granular fill layer overlying soft foundations.Öğe Evaluation of Granular Fill Layer Underlain by Soft Clay Soil Using Large Scale Cyclic Plate Loading Tests(Springer Int Publ Ag, 2023) Demir, Ahmet; Ok, Bahadir; Sarici, TalhaIn general, granular fill materials are widely used to construct new pavement and rehabilitate old pavement. For pavement design, it is essential to know the basic characteristics, such as the permanent deformation behavior of these materials. Considering this phenomenon, this study aims to explain the performance of granular fill layers in pavement systems using cyclic plate load tests. For this purpose, a large-scale cyclic plate load test facility, also known as pavement model testing (PMT), was developed to investigate the permanent deformation characteristics of the pavement structure. To conduct experiments, a standard pavement structure was built with granular fill layers on top of a soft clay subgrade and a geotextile between the subgrade and the base layer. The PMT was used to apply a 40 kN cyclic load through a steel plate with a 305 mm diameter for up to 10,000 cycles after the pavement structure was built. A total of four tests were carried out to evaluate the effects of the granular fill layer's thickness on the pavement's permanent deformation. Furthermore, an analytical solution was developed for the fill layer thickness using the test results. Additionally, the outcomes of some previous studies in the literature were compared to the ones that were obtained. The results of this study indicate that the permanent deformations of the pavement structure and the subgrade increased with the number of load cycles. The permanent deformations began to limit at 3000 cycles when the fill layer thickness was 20 cm, but it was observed that deformations did not limit at 3000 cycles when the fill layer thickness increased to 45 cm. Also, the permanent deformations decreased by two times when the granular fill layer thickness doubled appropriately.Öğe Evaluation of Rockfill Stabilized-Geosynthetics Reinforced Road Base with Repeated Plate Loading Tests(Mdpi, 2024) Demir, Ahmet; Ok, Bahadir; Sarici, TalhaIn this study, the performance of unpaved road sections over soft clay soil geosynthetic-reinforced and stabilized with rock fill layer was evaluated using repeated plate loading tests. A total of 10 field tests were carried out using a circular model rigid plate with a diameter of 0.30 m. The parameters investigated included the location and type of geosynthetics and loading conditions (number of loading cycle and traffic loading condition). Based on the test results, the least deformation was observed in the rockfill section. The geocell placed at a depth of one-third thickness of the granular fill layer from the top showed improved performance and was more effective as compared with other geosynthetic reinforcements. However, for granular fill geosynthetic-reinforced or stabilized with rock fill layer, the results demonstrate an improvement in the rutting performance of the pavement and the definite trend of increasing reloading elastic modulus, depending on the traffic loading situation. It has been also observed that the use of geocell or geogrid reinforcement in granular fill layer or more rigid rockfill layer provides an important increase in the modulus improvement ratio (MIR) by at least 36%, 45% and 60% compared to the granular fill section, respectively.Öğe Investigation of the construction and demolition materials reinforced by geosynthetics(Emerald Group Publishing Ltd, 2023) Ok, Bahadir; Sarici, Talha; Demir, Ahmet; Talaslioglu, Tugrul; Yildiz, AbdulazimMany researchers suggest using construction and demolition materials in engineering applications (C & D) rather than virgin aggregates (VA). However, the engineering properties of the C & D tend to be poorer than those of the VA. This study presents the results of plate loading tests performed on unpaved roads with the C & D, reinforced by different types of geosynthetics on the soft subgrade. As part of these tests, the effects of some geosynthetics' parameters such as (1) the embedment depth, (2) height and pocket opening of geocell, (3) the embedment depths and number of geogrids, (4) the distance between geogrids, and (5) the stiffness of geotextile on the bearing capacity of the unpaved road were investigated. Besides, the same plate loading test was also conducted on an unpaved road built by the VA. As a result of this study, although the performance of the C & D was determined to be less than that of the VA, it was concluded that the C & D performed well enough to be used as an alternative to the VA on unpaved roads. Besides, with a very small number of geosynthetics, it was determined that the C & D could have a better performance than that of the VA.Öğe Okulda diyabet programı kapsamında öğrencilere verilen diyabet eğitiminin etkinliğinin ölçülmesi(İnönü Üniversitesi, 2019) Demir, AhmetAmaç: Bu çalışma, "Okullarda Diyabet Programı" kapsamında öğrencilere yapılan diyabet eğitimlerinin, beslenme ve diyabet bilgi düzeylerine etkisini değerlendirmek amacıyla planlanan bir çalışmadır. Materyal ve Metot: Araştırmamız Adıyaman il merkezinde bulunan ortaokul 7. Sınıf ve lise 10. Sınıf öğrencilerinin diyabet eğitimi öncesi ve sonrası diyabet bilgi düzeylerinin ölçülmesi amacıyla yapılan descriptive (tanımlayıcı) özellikleri olan kesitsel (cross-sectional) bir çalışmadır. Çalışmamız toplam 344 ortaokul 7. Sınıf ve lise 10. Sınıf öğrencisine yapılmıştır. "Okullarda Diyabet Programı", Türkiye çapında yürütülen bir eğitim programıdır. Diyabet bilgi puanı; öğrencilerin diyabet ile ilgili sorulara verdikleri cevaplar puanlanarak elde edilmiştir. Bu formdan minimum sıfır (0), maksimum 100 puan alınabilmektedir. Verilerin normal dağılıma uygun olup olmadığı Shapiro Wilk normallik testi ile değerlendirilmiş ve yaş, diyabet bilgi puanının normal dağılıma uymadığı (p<0,05) görülmüştür. Bu nedenle bağımlı (paired) örneklerde niteliksel verilerde (biliyor-bilmiyor, evet-hayır vb.) Mc Nemar testi, ölçülebilir verilerde (puan toplamı vb.) Wilcoxon eşleştirilmiş iki örnek testi kullanılmıştır. Tüm değerlendirmelerde p<0,05 anlamlı olarak kabul edilmiştir. Bulgular: Katılımcıların bilgi puanlarında eğitim sonrasında anlamlı bir artış olmuştur. Kız öğrencilerin bilgi puanları erkek öğrencilerle eğitim öncesinde anlamlı fark içermemekteyken, eğitim sonunda kız öğrencilerin bilgi puanları erkek öğrencilere oranla daha fazla artmıştır. Çalışmaya katılan öğrencilerin %48.7'sinin akrabaları arasında en az bir diyabetli bulunmaktadır. Öğrencilerin diyabeti nereden öğrendikleri sorgulandığında; birinci sırayı aile cevabı almaktadır. Sonuç: Araştırmamız sürekli artan diyabetin olumsuz etkilerinden korunmak için yapılan eğitimlerin etkili olduğunu ve öğrencilerin bilgi düzeylerinin artmasına katkı sunduğunu göstermektedir. Okullarda Diyabet Programı kapsamında yapılan eğitim faaliyetleri devam etmelidir. Anahtar Kelimeler: Diyabet, Okullarda Diyabet Programı, Sağlık.Öğe Rosuvastatin's effects on ischemic skin flaps: Facts about statins' effects on skin flap viability(2021) Demir, Ahmet; Yasar, Emrah Kagan; Trabzonlu, Levent; Alagoz, Murat SahinAim: Statins are considered to be protective against ischemic injury because of their pleiotropic effects. In this animal study, the effects of high dose (40 mg/kg) rosuvastatin on ischemic skin flaps were investigated. Materials and Methods: Eighteen Wistar Albino male rats randomly divided into the treatment and the sham groups in equal numbers (n=9 in each group). Orogastric tubes were used both in the treatment and the sham group. Differently, in our study orogastric feeding started one day before the surgery and ended on the postoperative day seven. By this way we aimed to have enough circulating levels of agent in acute ischemia. Only the treatment group received rosuvastatin-supplemented water. Twenty-four hours after the first gavage application, caudally based, modified McFarlane flaps were elevated in 3x10 cm in size. After flap elevation procedure, the flaps were returned to their original location immediately. Results: The day after the last gavage application on postoperative day seven animals were sacrificed. Thereafter the digital images were obtained. The skin biopsies were taken by pathologist from three zones on each flap for histopathological assessment. Skin flap viability rate (p=0.508) and necrosis rate (p=0.453) did not show any difference between the groups Interestingly, the final weights of the animals were lower than their initial weights, but this was only significant for the study group (p=0.008), not for the sham group (p=0.400). There were no any expectations related with weight change of the animals before the statistical analysis. Conclusion: On the other hand, there are literature studies claiming that the statins are effective to increase ischemic skin flaps viability, this study contradicts earlier studies. Statins were not observed to have favorable effects on critically ischemic skin flap viability through their pleiotropic activity.
