A Numerical Investigation of Induced and Embedded Trench Installations for Large-Diameter Thermoplastic Pipes under High Fill Stresses

The induced trench installation method is applied by placing material with high compressibility on rigid pipes to reduce the earth pressures acting on them. Although the performance of this method for rigid pipes has been investigated, research on thermoplastic pipes is very limited. In this study, induced trench installation (ITI) and embedded trench installation (ETI) of large-diameter thermoplastic pipes subjected to high fill stresses were investigated by numerical analysis. The numerical model has been verified by considering the field experiments, and a series of analyses were carried out by placing Expanded Polystyrene Foam (EPS Geofoam) in ITI and ETI models. Pipe stresses and deflections were evaluated by considering the pipe diameter, stiffness, and backfill properties. The ITI and ETI models in thermoplastic pipes reduced the stresses acting on the pipes and increased the positive arching regardless of the deflection of the pipe. For pipes with an inner diameter of 0.762 to 1.524 m under 30 m of fill stress, approximately 1.5 to 3.0% deflection occurred. In the ETI model, the horizontal earth pressure in the spring line of the pipe decreased from 65 to 40% depending on the backfill type, and an approximately uniform stress distribution was formed around the pipe

A Numerical Investigation of Induced and Embedded Trench Installations for Large-Diameter Thermoplastic Pipes under High Fill Stresses

The induced trench installation method is applied by placing material with high compressibility on rigid pipes to reduce the earth pressures acting on them. Although the performance of this method for rigid pipes has been investigated, research on thermoplastic pipes is very limited. In this study, induced trench installation (ITI) and embedded trench installation (ETI) of large-diameter thermoplastic pipes subjected to high fill stresses were investigated by numerical analysis. The numerical model has been verified by considering the field experiments, and a series of analyses were carried out by placing Expanded Polystyrene Foam (EPS Geofoam) in ITI and ETI models. Pipe stresses and deflections were evaluated by considering the pipe diameter, stiffness, and backfill properties. The ITI and ETI models in thermoplastic pipes reduced the stresses acting on the pipes and increased the positive arching regardless of the deflection of the pipe. For pipes with an inner diameter of 0.762 to 1.524 m under 30 m of fill stress, approximately 1.5 to 3.0% deflection occurred. In the ETI model, the horizontal earth pressure in the spring line of the pipe decreased from 65 to 40% depending on the backfill type, and an approximately uniform stress distribution was formed around the pipe

Depolanmış Tarama Çamurlarının Sıkışabilirlik ve Mukavemet Davranışının Laboratuvar ve Arazi Deneyleri ile İncelenmesi

Bu çalışmada, Haliç tarama çamurunun karada depolanması durumunda, kendi ağırlığı altında ve sürşarj yükleri etkisindeki sıkışabilirlik ve mukavemet davranışı incelenmiştir. Bu amaçla, taranan çamurun karada depolanması durumunda kendi ağırlığı altında konsolidasyon davranışını incelemek için laboratuvarda dört adet büyük boyutlu model deney ve bir adet küçük boyutlu sedimantasyon deneyi gerçekleştirilmiştir. Bu deneylerde kendi ağırlığı altında konsolidasyondan sonra alınan örselenmemiş numuneler üzerinde yapılan ödometre deneyleri ile sürşarj yükleri etkisindeki sıkışabilirlik ve model deneylerde yapılan veyn deneyi ile derinlik boyunca drenajsız kayma mukavemeti ölçülmüştür. Zeminin kendi ağırlığı altındaki konsolidasyon davranışını incelemek için gerçekleştirilen model deneyler ve sedimentasyon deneyinden ölçülen oturma değerlerinden konsolidasyon katsayısı cv’nin 0.91-10.72 m2/yıl aralığında ve drenajsız kayma mukavemetinin de 4-20 kPa arasında değiştiği belirlenmiştir. Tarama çamurunun karada depolanmasından 13 yıl sonra yapılan arazi deneylerinden belirlenen drenajsız kayma mukavemeti (SPT N darbe sayısına bağlı olarak ve UU deneylerinden) benzer şekilde cu=4-20 kPa arasında değişim göstermiştir. Haliç’ten taranan ve eski taş ocağında depolanan yaklaşık 25 m kalınlıktaki tarama çamurunun düşük taşıma gücüne ve yüksek sıkışabilirliğe sahip olduğu tespit edilmiştir

Investigation of Compresibility and Strength Behaviour of Deposited Dredged Slurries by Laboratory and Field Tests

Bu çalışmada, Haliç tarama çamurunun karada depolanması durumunda, kendi ağırlığı altında ve sürşarj yükleri etkisindeki sıkışabilirlik ve mukavemet davranışı incelenmiştir. Bu amaçla, taranan çamurun karada depolanması durumunda kendi ağırlığı altında konsolidasyon davranışını incelemek için laboratuvarda dört adet büyük boyutlu model deney ve bir adet küçük boyutlu sedimantasyon deneyi gerçekleştirilmiştir. Bu deneylerde kendi ağırlığı altında konsolidasyondan sonra alınan örselenmemiş numuneler üzerinde yapılan ödometre deneyleri ile sürşarj yükleri etkisindeki sıkışabilirlik ve model deneylerde yapılan veyn deneyi ile derinlik boyunca drenajsız kayma mukavemeti ölçülmüştür. Zeminin kendi ağırlığı altındaki konsolidasyon davranışını incelemek için gerçekleştirilen model deneyler ve sedimentasyon deneyinden ölçülen oturma değerlerinden konsolidasyon katsayısı cv’nin 0.91-10.72 m2/yıl aralığında ve drenajsız kayma mukavemetinin de 4-20 kPa arasında değiştiği belirlenmiştir. Tarama çamurunun karada depolanmasından 13 yıl sonra yapılan arazi deneylerinden belirlenen drenajsız kayma mukavemeti (SPT N darbe sayısına bağlı olarak ve UU deneylerinden) benzer şekilde cu=4-20 kPa arasında değişim göstermiştir. Haliç’ten taranan ve eski taş ocağında depolanan yaklaşık 25 m kalınlıktaki tarama çamurunun düşük taşıma gücüne ve yüksek sıkışabilirliğe sahip olduğu tespit edilmiştir

Investigation of a laterally loaded model pile behaviour in sand by means of experimental and numerical methods

Niyazi Uğur TERZİ (Aksaray Üniversitesi yazarı)Bu çalışmada, farklı kum ortamlarında yerleştirilmiş olan bir kazık modelinin yanal yüklemeler altındaki gerilme-şekil değiştime ve yerdeğiştirme davranışı incelenmiştir. Labaratuvar ortamında yürütülen çalışmada, dairesel bir alüminyum kazık, deney kutusu, yükleme düzeneği, yer değişimi ve şekil değişimi ölçerler kullanılmıştır. Yağmurlama sistemi kullanılarak eşdeğer sıkılık ve homojen bir dolgu ortamı oluşturulmuştur. Deneysel çalışmalarda model kazığın kademeli yüklemeler altındaki gösterdiği davranışı deneysel olarak saptanmıştır ve daha sonra kazık davranışı, tasarımcılar tarafından yaygın olarak kullanılan p-y ve yatak katsayısı yöntemleri kullanılarak analiz edilmiştir. Nümerik çalışmalar LPILE ve SAP 2000 programlarında gerçekleştirilmiştir. Yapılan çalışmalar sonucunda, p-y yönteminin yatak katsayısı yönteminden daha güvenilir sonuçlar ortaya koyduğu saptanmıştır. Kumun sıkılık derecesinin zemin reaksiyonu üzerindeki etkisi görülmüştür. Son olarak ölçüm aygıtlarının kalibrasyonunda kullanılan Daley yönteminin güvenilir olduğu anlaşılmıştır.In this study, stress-strain relation and deformation behavior of laterally loaded pile which is located in different sand embedment is investigated. A circular aluminum pile, test box, loading system, strain gauge rosettes and linear position transducers were used in the laboratory test. Uniform relative density and homogeneous embedment medium in the test box were achieved by using sand pluviation system. The behavior of aluminum pile loaded incrementally at its head is obtained experimentally and then p-y method and subgrade reaction method which is commonly used by designers are employed to model the numerical behavior of the pile. Numerical studies were performed by using LPILE and SAP 2000 computer programs. Based on the findings, the p-y method estimates the pile head deflection more accurately than subgrade reaction method particularly high lateral deflections of pile head. The experimental test studies show that relative density of sand embedment is very effective on occurrence of soil reaction. Finally the reliability of Daley calibration method which is used in instrumentation was evaluated

Experimental investigations of backfill conditions on the performance of high-density polyethelene pipes

WOS: 000301574000007In this study, a series of laboratory tests on 100-mm-diameter high-density polyethylene (HDPE) 100 PE flexible pipe buried in poorly graded Sile quartz sand with different relative densities are described. The laboratory tests were performed in a 40-mm-thick plexiglass fronted test tank that replicated a classical trench section in field conditions. The HDPE flexible pipe was positioned against the glass with its longitudinal axis perpendicular to the glass. This allowed direct observation of the backfillpipe interactions. Three high-definition photogrammetric cameras were used to capture the photogrammetric images through the glass allowing the discrete measurement and image processing of the deformation patterns of the pipe conduit during the pipe installation and incremental surcharge loading. Vertical loads were applied in increments of 10150 kPa using air pressure membranes. Electric resistant strain gauges measured the bending moments of the pipe walls under vertical surcharge loadings. For each loading step, the vertical deformation of the pipe crown was also measured using linear position transducers. According to the test results, it is understood that the installation technique and backfill relative density have an important effect on circumferential strains, performance, and deformation characteristics of HDPE pipes. It was also observed that close-range image processing is a very simple and appropriate method for measuring three-dimensional pipe deformations under various conditions.TUBITAK [104I107]This study is supported by the TUBITAK 104I107 project

Laboratory and Field Observations for Golden Horn Marine Clay

Istanbul, the largest city in Turkey and one of the major metropolitan areas in the world, cleaned one of its environmentally polluted areasGolden Hornby dredging 5 million m3 of the bottom sediments and pumping the resulting sludge to a storage area behind a dam built at an abandoned rock quarry site in Alibey district. The reclamation of the land that formed over the storage area of Golden Horn dredged material is socially and economically very desirable. In this paper, results from experimental studies that are focused on determining the shear strength behavior of the dredge material and undisturbed soil are presented. Slurry consolidometer test, large model tests and small model tests are used to consolidate the dredged soil samples from Halic to simulate the natural consolidation behavior of these soils. Shear strength parameters are determined by laboratory vane tests; unconfined compression tests; undrained-unconsolidated (UU) and consolidated-undrained (CU) triaxial tests on samples that are obtained through in situ undisturbed samples and laboratory model tank and slurry consolidation. Moreover, the effects of fly ash and lime additives on the undrained shear strength were determined by mixing the materials with the dredged clay from Golden Horn during the model experiments conducted in the laboratory. Based on these findings, equations are proposed that govern the relationships between undrained shear strength and water content value

The effect of probiotic and omega-3 supplements on total oxidant and total antioxidant levels in experimental colitis

Objective: Treatment of inflammatory bowel disease (IBD) usually involves medical therapy. For this reason, it is recommended to seek alternative treatment methods such as nutritional therapy. The aim of the study is to evaluate the effects of probiotics and omega-3 fatty acids on total oxidant and total antioxidant levels in an experimental colitis model. Methods: Mice were randomly divided into five groups (n= 10/group) as healthy group, colitis group, group treated with probiotics (VSL#3), group treated with omega-3 (w-3), and group treated with both probiotics and omega-3. To induce experimental colitis, 200 mg/kg dinitrobenzene sulfonic acid (DNBS) + 30% ethanol combination was rectally administered to anesthetized mice. Total oxidant (TOS) and total antioxidant (TAS) levels were measured at the tissue level. Results: Lower concentrations of TOS were observed in the probiotics groups (2.11 +/- 0.23 mmol H2O2 Eq/L), probiotics+omega-3 (2.56 +/- 1.18 mmol H2O2 Eq/L), and omega-3 (3.02 +/- 1.88 mmol H2O2 Eq/L) groups compared to the colitis group (3.11 +/- 0.91 mmol H2O2 Eq/L) (p>0.05). Higher TOS and TAS level were observed in the control colitis group compared to other groups; however, the differences were not statistically significant. Conclusion: Our findings showed that TAS and TOS levels were positively affected by the use of probiotic supplements in IBD. It was determined that using w-3 alone was ineffective in decreasing TOS levels. Studies with higher dosages and longer treatment periods are needed to better observe the effects of nutritional supplements on TOS and TAS parameters in inflammatory bowel diseases

Combined therapy with probiotic VSL#3 and Omega-3 fatty acids attenuates colonic injury and inflammation in chronic DNBS-induced colitis in mice

Inflammatory bowel disease (IBD) is a progressive chronic inflammatory disease affecting the gastrointestinal tract with a chronic relapsing and remitting disease course. While there are a number of therapeutic strategies available to treat IBD, a definitive treatment still hasn't been defined, leading to alternative treatment options including nutritional support. Herein, we planned to investigate the combined impact of probiotics and omega-3 (omega-3) fatty acids on inflammatory response and intestinal epithelium in chronic colitis induced by 2,4-Dinitrobenzenesulfonic acid (DNBS). Fifty BALB/c mice were randomly divided into five groups: non-colitis control, colitis with no treatment applied (control colitis), colitis treated with probiotics (VSL#3), colitis treated with omega-3, and colitis treated with both VSL#3 and omega-3. Colitis was induced by intrarectal administration of 2,4-Dinitrobenzenesulfonic acid (DNBS) in all groups but the non-colitis control group. Ten days after the DNBS period, phosphate-buffered saline (for both the non-colitis control and colitis control groups), VSL#3, omega-3, or VSL#3 + omega-3 treatments were administered intragastrically to their respective groups for 10 days. By analyzing the colonic expression of interleukin IL-6, IL-10, and IL-17A, and interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) levels, results revealed that levels of IFN-gamma IL-17, and TNF-alpha were significantly higher in the control colitis group when compared with the other groups. The control colitis, colitis +VSL#3, and colitis + omega-3 groups exhibited higher scores of microscopic damage compared to the non-colitis control and colitis + VSL#3 + omega-3 groups. The closest histological image to the non-colitis control group was presented in the colitis + VSL#3 + omega-3 group. The findings indicate that the combined effect of probiotics and omega-3 fatty acids might have a protective effect against colon injury and inflammation by creating synergistic effects. However, more research is needed to understand the exact mechanism of this synergistic effect and to examine how this therapeutic approach can be used in inflammatory bowel diseases