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Öğe Centrifuge model tests and numerical analysis of uplift capacity of strip anchors in geogrid-reinforced sand(MDPI, 2023) Bildik, Selçuk; Dickin, Edward Alan; Keskin, Mehmet Salih; Ilamparuthi, Kanniappan; Laman, MustafaAnchor-type foundations are one of the foundation types used in structures subject to tensile forces. These anchors are generally designed according to the weight of the soil on them depending on the depth they are buried at and the frictional resistance obtained from the failure surfaces during failure. One method of increasing the uplift capacity of the foundation without increasing the burial depth is the use of geogrid material. In this study, the uplift capacities of strip anchor plates at different embedment depths were investigated by considering the geogrid effect placed in different combinations. The aim of the study is to investigate whether a more economical solution can be obtained by using geogrid without increasing the embedment depth of the anchor plate. Experiments were carried out using centrifugal experimental setup, which gives values closer to the real results. The tests were performed on sand of two different densities for anchor burial depths H/B = 2 and H/B = 5. According to the results, the uplift capacity is significantly improved when geogrid is used. As the reinforcement configuration, the use of a single geogrid layer placed just above the anchor plate with an inclination angle of 45 degrees gave more effective results than using the geogrid horizontally and vertically. In the study, up to 98% increases in uplift capacity were obtained with reinforcement. In addition, the prototype model was analyzed with a numerical program based on the finite element method, and the results were compared with the experimental results. As a result of the comparison, it was observed that the experimental and numerical results were compatible with each other. Suggestions for practice are presented using the results obtained.Öğe Experimental and Numerical Studies of Strip Footings on Geogrid-Reinforced Sand Slope(Springer Heidelberg, 2014) Keskin, M. Salih; Laman, MustafaAn experimental investigation into the ultimate bearing capacity of the strip footings resting on a sand slope with and without geogrid reinforcement is reported. The parameters investigated are the effect of the depth of the single layer of geogrid, vertical spacing of geogrid layers, number of geogrid layers, length of geogrid layers, the effects of the angle of the slope inclination, the relative density of sand, and type of reinforcement. A group of finite-element analyses was also carried out on a model slope. The results proved that the reinforcement had a considerable effect on the ultimate bearing capacity of the strip footings on a sand slope. The improvement in the bearing capacity of the strip footing on a reinforced slope was found to be strongly dependent on the slope angle, the relative density of sand, and the tensile strength of geogrid reinforcement. A satisfactory agreement between the experimental and numerical test results on a general trend of behaviour and optimum geometry of reinforcement placement is observed. Based on the model test results and the finite-element analyses, optimum values of the geogrid parameters for maximum reinforcing effect are discussed and suggested.Öğe Experimental and numerical studies of vertical stresses beneath the circular footings on sand(MDPI, 2023) Keskin, Mehmet Salih; Bildik, Selçuk; Laman, MustafaThis paper presents experimental and numerical studies of the vertical stress distribution beneath the centerline of circular footings resting on sand. Vertical stress values due to circular load in medium-dense sand were measured using soil stress transducers. Reduced-scale laboratory model tests were carried out in a square-shaped test box, and vertical stresses were measured at the centerline of the circular footing at different depths of the sand. In order to determine the effect of footing width on vertical stress distribution, laboratory experiments were performed on circular footings of different diameters. In addition, a series of finite element analyses was carried out on the test model to validate the findings of the experimental study. In the numerical analysis, the sand was modeled as a non-linear elastoplastic material. The analyses were performed using the finite element method with two-dimensional axisymmetric and three-dimensional conditions. The results obtained from laboratory model tests and numerical analysis were compared with the vertical stress values obtained from the theoretical solution in the literature. Vertical stress distribution in horizontal planes at any depth from the footing base shows the same characteristic form in all methods. However, some differences were observed between experimental, numerical, and theoretical results and were discussed.Öğe Experimental study of bearing capacity of strip footing on sand slope reinforced with tire chips(Techno-Press, 2014) Keskin, Mehmet Salih; Laman, MustafaTire chips and tire chips-soil mixtures can be used as alternative fill material in many civil engineering applications. In this study, the potential benefits of using tire chips as lightweight material to improve the bearing capacity and the settlement behavior of sand slope was investigated experimentally. For this aim, a series of direct shear and model loading tests were conducted. In direct shear tests, the effect of contents of the tire chips on the shear strength parameters of sand was investigated. Different mixing ratios of 0, 5, 10, 15 and 20% by volume were used and the optimum mixing ratio was obtained. Then, laboratory model tests were performed on a model strip footing on sand slope reinforced with randomly distributed tire chips. The loading tests were carried out on sand slope with relative density of 65% and the slope angle of 30 degrees. In the loading tests the percentage of tire chips to sand was taken as same as in direct shear tests. The results indicated that at the same loading level the settlement of strip footing on sand-tire chips mixture was about 30% less than in the case of pure sand. Addition of tire chips to sand increases BCR (bearing capacity ratio) from 1.17 to 1.88 with respect to tire chips content. The maximum BCR is attained at tire chips content of 10%.Öğe Kuma Oturan Yüzeysel Temellerde Temel Boyutunun Taşıma Kapasitesine Etkisi(Çukurova Üniversitesi, 2012) Keskin, M. Salih; Laman, Mustafa; Uğur, Samet; Bildik, SelçukBu çalışmada, kumlu zeminler üzerine oturan şerit temellerin taşıma kapasitesi sayısal ve teorik olarak analiz edilmiştir. Bu amaçla, kum zemine oturan bir şerit temel modeli oluşturularak üç boyutlu Plaxis3D bilgisayar programı ve literatürdeki mevcut teorik yöntem (Terzaghi Yöntemi) kullanılarak analizler gerçekleştirilmiştir. Sayısal analizlerde, farklı temel genişlikleri kullanılarak, temel genişliğinin, taşıma kapasitesi, qu ve taşıma gücü katsayısına, N? etkisi incelenmiş ve teorik yöntemle karşılaştırmalar yapılmıştır. Sayısal analiz sonuçları, temel genişliğinin artmasıyla şerit temelin taşıma kapasitesinin arttığını, taşıma kapasitesi katsayısının ise azaldığını göstermiştirÖğe Model studies of bearing capacity of strip footing on sand slope(Korean Society Of Civil Engineers-Ksce, 2013) Keskin, M. Salih; Laman, MustafaAn experimental investigation into the ultimate bearing capacity of strip footing on sand slope is reported. The parameters investigated are the effect of setback distance of the footing to the slope crest, slope angle, relative density of sand and footing width on the ultimate bearing capacity of strip footings. A series of finite element analyses was additionally performed on a prototype slope to ascertain the validity of the findings from the laboratory model tests and to supplement the results of the model tests. The agreement between observed and computed results is found to be reasonably well in terms of load-settlement and general trend of behavior. The results show that the ultimate bearing capacity increases with increase in setback distance, relative density of sand, footing width and decrease in slope angle. At a setback distance of five times of the width of the footing, bearing capacity remains constant like that of a footing on level ground.
