Anchored Sheet Pile Wall Design in Expansive Soils

Expansive soils cause damage to civil engineering structures in various parts of the world, because they swell when absorb water and shrink when dry out. Due to swelling pressures, retaining walls can be subjected to additional lateral pressures causing increased wall deformations and bending moments. Anchor forces can also increase, if the walls are anchored. When expansive soils are present behind retaining walls, swell pressures should also be considered during design in addition to the traditional lateral earth pressures. This study proposes a method to predict potential swell pressures acting on retaining walls for use in design of these walls. A parametric study using the limit equilibrium approach was performed to investigate the effect of swell pressures on the design of anchored sheet pile walls in expansive soils. The results of the study show that the presence of expansive soils can significantly affect earth retaining structures and swell pressures should be considered in the design of retaining walls when the expansive soils are present at the site

Öğrencilerin Kimyasal Denge Konusundaki Kavram Yanılgıları

The purpose of this study was to determine students’ misconceptions regarding the concepts of chemical equilibrium. To diagnose students’ misconceptions in this area, a written test was administered to 216 11th grade high school students after their formal class schedule. The original test was developed by Hackling and Garnett, 1984 and translated and adopted into Turkish by the authors. The test included 47 multiple choice and true-false items and its reliability coefficient was found to be 0,87. An interview was also conducted with 20 students to establish their reasons for misconception with the open-ended questions. Analysis of responses revealed widespread misconceptions among students in the areas related to (1) approaches to chemical equilibrium, (2) characteristics of chemical equilibrium, (3) changing chemical equilibrium conditions, and (4) adding a catalyst.Bu çalışmanın temel amacı, öğrencilerin kimyasal denge ile ilgili kavram yanılgılarını belirlemektir. Öğrencilerin bu konudaki yanlış kavramlarını tespit etmek için, hazırlanan bir test, 216 lise üçüncü sınıf öğrencisine, konu sınıfta anlatıldıktan sonra uygulanmıştır. Testin orijinali Hackling and Garnett tarafından 1984 yılında geliştirilmiştir. Bu test Türkçe'ye çevrilmiş ve yeniden gözden geçirilerek Türkiye şartlarına uyarlanmıştır. Test doğru- yanlış ve çoktan seçmeli sorulardan oluşmuş ve güvenirlik katsayısı 0,87 olarak hesaplanmıştır. Ayrıca, öğrencilerin kavram yanılgılarının nedenlerini anlamak için 20 öğrenci ile mülakat yapılmıştır. Cevapların analizi, öğrencilerin şu konularda yaygın olarak yanlış kavramlara sahip olduğunu göstermiştir: (1) Tepkime dengeye gelirken, (2) kimyasal dengenin özellikleri, (3) kimyasal denge koşullarının değiştirilmesi ve (4) katalizör ilavesi

Spatial Variability of Subsurface Soil Conditions Causing Roadway Settlements

Settlement of problematic soils constituting the roadway subgrade may result in pavement distress and structural failure, requiring periodic pavement patching and resurfacing. Many of these problems occur as a result of the settlement of soft cohesive and organic soils. Due to the extent of roadway projects and the limited frequency of boring locations, spatial variability of subsurface soil conditions, and sometimes due to an inadequate extent of exploration, these problematic soils may not be identified suitably during subsurface explorations. An extensive subsurface exploration program was implemented for detailed characterization of subsurface conditions for a relatively short section of an existing roadway experiencing continuing settlements. This paper presents some of the exploration results, assesses the spatial variability of the subsurface soil conditions, and comments on the effect of spatial variability of subsurface conditions on the roadway\u27s performance

Comparative Evaluation of the Shaping Ability of Five Different Nickel-Titanium Rotary File Systems in Simulated Canals

Objectives: The aim of this study was to compare the simulated canal shaping efficiencies of five different NiTi rotary file systems. Materials and Methods: In the study, 100 transparent resin blocks with J-shaped canals were randomly divided into five groups (n=20). Simulated canals were shaped with VDW.Rotate (VR), TruNatomy (TRN), HyFlex CM (HF), EdgeFile X7 (EF), or ProTaper Next (PTN) files. Ten measuring points were detected on the pre- and post-preparation images taken from the blocks and superimposed. After preparation, the total canal width and the amount of transportation were calculated for the determined measuring levels. Zipping and ledge formation, instrument fracture and deformation, and change in working length were evaluated. The data were statistically analyzed with the Kolmogorov-Smirnov test, one-way ANOVA, Tukey test, Chi-Square test, and a Monte Carlo version of the Fisher Exact tests. The error level was taken as 0.05. Results: There were significant differences between the groups at all measuring levels in terms of total canal width after instrumentation (p = 0.001). Significant differences in the amount of transportation were found between the groups (p = 0.001) except at levels 4 (p = 0.169) and 10 (p = 0.054). Zip and instrument fractures did not occur in any group. 3 EF size 25/.04 files were deformed (p = 0.021). There was no significant difference between the groups in terms of ledge formation and working length change (p > 0.05). Conclusions: According to findings obtained in the study, transportation occurred at all 10 measuring levels with all file systems used. HF and EF systems were found to be more reliable in terms of transportation in the middle and coronal regions. Wider canal preparation was obtained with the PTN system in the middle and coronal regions

EFFECTS OF HIERARCHICAL PLATEUING AND PERCEIVED INSIDER STATUS ON PERFORMANCE GOAL ORIENTATION AND INNOVATIVE BEHAVIOR: THE MEDIATING ROLE OF ORGANIZATIONAL IDENTIFICATION

Rekabetin yoğunlastığı günümüz sartlarında örgütler yeniliklere ayakuydurmak zorundadır. Yenilikçi ortamın olusturulması için de bireylerin motiveedilerek bazı hedeflere yönelmesi sağlanmalıdır. Bu çalısmada hiyerarsikplato, kendini isletmeden hissetme ve özdeslesmenin yenilikçi davranıs veperformans hedefine yönelim değiskenleri üzerindeki etkiler sorgulanmıstır.Ankara'da güvenlik sektöründe çalısmakta olan 486 katılımcıdan elde edilenbulgular sonucunda kendini isletmeden hissetmenin ve hiyerarsik platonunözdeslesme üzerinde pozitif etkisinin olduğu saptanmıstır. Ayrıca kendiniisletmeden hissetmenin yenilikçi davranıs ve performans hedefine yönelimüzerinde pozitif etkisinin olduğu ve bu etkide özdeslesmenin tam aracılık ettiğigözlenmistir. As competition conditions become intense, organizations today have to keeppace with innovation. For the creation of innovative environment, individualsshould be motivated to orientate to some goals. In this study the effects ofhierarchical plateuing, perceived insider status and organizationalidentification are investigated on performance goal orientation and innovativebehavior. The sample is composed of 486 respondents who is working insecurity sector in Ankara. The results reveal that direct positive effects ofhierarchical plateuing and perceived insider status on organizationalidentification. The results also demonstrate that positive effects of perceived insider status on innovative behavior and performance goal orientation aremediated by organizational identification

Interface Friction Parameters for the Mathematical Modeling of Shell Structures with Infill

Thin metal or reinforced concrete shells with granular infill structures are considered in this article. These structures are massive and they are used as support for the construction of berthing quays, piers, artificial islands, shore protection, and other structures of coastal infrastructure. It is more convenient to use the thin shell structures during the development of the Arctic shelf, because it is possible to install them from the ice side. In addition, it is possible to enhance the technology and install thin shells with infill on deeper solid foundation layers. A mathematical model for the stresses on a compressible foundation soil in front of a thin cylindrical shell with infill due to the eccentric loading is developed. A modeling and experimental determination of the interface strength of the contact surface between the infill and the inner surface of the shell is proposed. The details of the construction stages and testing of the physical model used for the experiments are discussed. The effects of the interface friction on the shell behavior and on the foundation stresses in front of the wall are investigated. The influence of parameters affecting the interaction between the soil infill and the inner surface of the shell material is determined. It is based on a comparison of experimental results with calculations performed using the proposed mathematical model. The obtained parameters and proposed methods can be used in numerical simulations using the finite element method to analyze and design the thin shell structures with soil infill. The findings of the study and proposed methods can also be applied to the thin shell structures used in other facilities such as hydraulic, industrial, civil, and transportation

INITIAL EXPERENCE WITH UROLOGIC LAPARASCOPIC SURGERY IN OUR CLINIC AND THE LEARNING PROCESS

Amaç: Ağustos 2009-Mart 2010 tarihleri arasında kliniğimizde gerçekleştirilen laparoskopik ameliyatların sonuçları ve komplikasyonları geriye dönük olarak değerlendirildi. Gereç ve yöntem: Kliniğimizde Ağustos 2009-Mart 2010 tarihleri arasında 32 hastaya (17 erkek, 15 kadın) laparoskopik ameliyat uygulandı. Ortalama yaşları 51,7 ± 14,3 (19- 72) yıl olan hastaların 15'i renal kitle, 5'i nonfonksiyone böbrek, 4'ü üreter taşı, 3'ü sürrenal kitle, 3'ü üreteropelvik bileşke darlığı, 2'si böbrek kisti nedeniyle ameliyat edildi. Laparoskopik girişimlerin 19'u transabdominal, 13'ü ise retroperitoneal yöntemle gerçekleştirildi. Her iki yöntemde de ortalama trokar yerleştirme süresi 16,6 ± 3,0 (15-25) dakikaydı. Bulgular: Transabdominal ve retroperitoneal tüm girişimlerin ortalama ameliyat süresi 173,3 ± 51,8 (90-300) dakikaydı. Perop ve postop dönemde ortalama 0,8 ± 1,5 (0-7) ünite eritrosit süspansiyonu kullanıldı. Hastalar ortalama 1,1 ± 0,3 (1-2) günde mobilize edildiler. Ameliyat sonrası dönemde ağrı kesici olarak 2,3 ± 0,6 (1-4) gün nonsteroid antiinflamatuar ilaç kullanıldı. Hastaların sondası ortalama 2,8 ± 2,8 (1-13) günde, dreni ise 4,9 ± 3,0 (2-14) günde çekildi. Hastanede ortalama kalış süresi 6,0 ± 3,1 (2-14) gündü. Dört (%12,5) hastada (3 renal kitle, 1 sürrenal kitle) renal ven yaralanmasına bağlı kanama nedeniyle açık operasyona geçildi. Bu hastalara perop dönemde 2 ünite eritrosit süspansiyonu verildi. Sonuç: Laparoskopi öğrenme eğrisi uzun olan cerrahi bir tekniktir. Transabdominal ve retroperitoneal laparoskopik girişimler düşük morbidite ve komplikasyon oranları, yüksek hasta memnuniyeti ve kısa hastanede kalış süresi ile tercih sebebidir. Bu minimal invaziv yöntemin sunduğu avantajlardan, değişik patolojileri olan hastalar yararlanabilmektedir. SUMMARY Objective: The results of the laparoscopic surgeries performed in our clinic between August 2009 and March 2010 and the complications that occurred due to these surgeries were evaluated retrospectively. Material and method: Thirty-two patients (17 men, 15 women) underwent laparoscopic surgery in our clinic. The mean age of the patients was 51.7 ± 14.3 (19-72) years and the indications for surgery were renal mass in 15 patients, non-functional kidney in 5 patients, ureter stone in 4 patients, adrenal mass in 3 patients, ureteropelvic junction obstruction in 3 patients and renal cyst in 2 patients. Of the 32 laparoscopic interventions, 19 were performed transabdominally and 13 were performed retroperitoneally. For both methods, the mean throcar placement duration was 16.6 ± 3.0 (15-25) minutes. Results: Mean duration of surgery was 173.3 ± 51.8 (90-300) minutes for the transabdominal and retroperitoneal interventions. An average of 0.8 ± 1.5 (0-7) units of erythrocyte suspension were used peroperatively and postoperatively. The patients were mobilized at 1.1 ± 0.3 (1-2) days. Nonsteroid anti-inflammatory drugs were administered as analgesics for 2.3 ± 0.6 (1-4) days, on average. The urethral catheters were removed after 2.8 ± 2.8 ( 1-13) days and the drainage tubes were removed after 4.9 ± 3.0 (2-14) days. Mean hospital stay was 6.0 ± 3.1 (2-14) days. Four patients (12.5%, 3 with renal mass and 1 with surrenal mass) were converted to open surgery due to renal vein injury. Peroperatively, 2 units of erythrocyte suspension were given to these patients. Conclusion: Laparoscopy is a surgical technique that requires a long learning curve. Transabdominal and retroperitoneal laparoscopic interventions are preferable since they are associated with low morbidity, low complication rates, high patient satisfaction and short hospital stay. Patients with various pathologies may benefit from the advantages offered by this minimal invasive method

Mathematical Model of the Shell with the Infill for Retaining Structures

A description of finite element model and analysis of a shell with an infill is performed. A large diameter thin cylindrical shell structure with the edge leaning against compressible foundation soil is analyzed. Different materials are considered individually for the models of each structure shell and infill component (metal or reinforced concrete shell, and granular or elastic infill in a shell and foundation soil loaded by the structure). Contact conditions between 1) the infill and the shell’s inner surface and 2) between the foundation material and the shell edge are analyzed. An example of calculating strain conditions in the shell according to the proposed finite element model and tasks of its development process and specification are provided in this paper

Effect of Subsurface Soil Conditions on Floodwall Behavior

Cantilever sheet piles or sheet piles with concrete cap above the ground surface I-walls are commonly used as floodwalls. The current design practice of cantilever sheet pile walls are based on horizontal force and moment equilibrium using active and passive earth pressures. Conventional methods used in the design of walls do not provide information on soil and wall deformations. Furthermore, the traditional design approach, only considers soils above the bottom of pile, i.e. the soils in direct contact with the wall, and does not take into account the effect of soils below the bottom of pile. However, due to a large area loading during a flooding event soils below the piles are also affected and go through deformations. The soil deformations occurring below the piles consequently affect the wall behavior and deformations. The effect of varying soil conditions below the bottom of piles on the behavior of cantilever walls during flooding were analyzed in this study. The finite element method was used to perform numerical analyses. This paper presents the results and findings of the parametric study performed

Modeling Viscoelastic Behavior of Polyethylene Pipe Stresses

Polyethylene pipes are commonly used for new and existing pipeline systems. The stresses developed in the polyethylene pipes affect the behavior of other pipe materials in the system to which they are connected. The overall behavior of the pipeline depends on the soil-pipe interaction characteristics; however, understanding and modeling the polyethylene pipe stresses as a first step without the influence of other factors is necessary. Laboratory tests were performed to investigate the time-dependent stress relaxation behavior of polyethylene pipe under mechanical and thermal loading conditions. Analytical methods using convolution integrals and numerical modeling using finite elements were used to model stress relaxation behavior monitored during the tests performed. The results show that the pipe thermal stresses are significantly less than the design stresses typically used by utility companies. In addition, linearly viscoelastic material characterization can be used to predict polyethylene pipe behavior for the range of stresses expected to occur in buried polyethylene pipes exposed to thermal loading. This article presents the test results as well as analytical and numerical results for modeling and predicting stresses in polyethylene pipes