توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱A survey of soft approach coastal defence methods
اطلاعات انتشار: همایش ملی یافته های نوین در مهندسی عمران، سال
تعداد صفحات: ۸
The coast is not a permanent line to be drawn on a map, but a dynamic environment in which land and sea are constantly interacting (eroding and accreting) in response to external factors, both natural and anthropogenic in origin, and acting on a whole range of time scales. By using output from research programs, we now have a more complete understanding of how coastal processes operate, and how processes operating on one part of the coast may be closely linked to the behavior of adjacent beaches is respect of sediment supply and sediment movement. The coastline is generally a highly populated area, both in respect of high resident numbers, and a large transient population who visit during the summer as tourists. Estimates from Goldberg(1994) state that 50 percent of the world’s population lives within 1km of the coastal zone, a figure expected to increase by 1.5 percent by 2010. Given this population it is not surprising that many coastal areas are highly developed and, thus have an associated high land value. In such situation, it is imperative that the development is protected from the sea; soft form of defense structure is an obvious solution to the protection of seas.<\div>

۲A Comparison between Finite Element and Smoothed Particle Hydrodynamics’ Simulations of Dam Break
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۸
Modeling of free surface flows is one of the main challenges in computational fluid dynamics (CFD). Dam break, as a free surface flow producer, is very important in industrial and environmental works and is usually applied to evaluate the performance of numerical modeling methods. In a dam break, because of a sudden break of a holding barrier, a large amount of water is accidentally released downstream. In this study, two numerical models for solving the dam break problem are developed and the efficiency of them is compared together. In the first model, Navier–Stokes equations for incompressible fluid are solved using a Characteristic–Based Split (CBS) finite element method on an unstructured triangular grid. The second numerical model solves the aforementioned equations with a meshless method entitled as Smoothed Particle Hydrodynamics (SPH) method. The results show that the developed SPH model provides better efficiency and accuracy than the CBS finite element method<\div>

۳Investigation in to the behavior of buckling and post buckling of the braces in jack case due to punch through of a jack up
اطلاعات انتشار: نهمین همایش بین المللی سواحل، بنادر و سازه های دریایی، سال
تعداد صفحات: ۸
As a very useful and movable tool for drilling operations of oil and gas industry in shallow water, jack–up units have been used widely for several decades. While originally designed foruse in shallow waters, there is growing demand for their use in deeper waters and harsher environments. In general, a jack–up structure consists of a hull and three K–lattice legs resting on spudcan footings. Each leg has three chords. When the structure is towed to site and preloaded tothe desirable penetration, the hull is then jacked up. During the preloading of a three leg unit, ballast water is gradually added to the preload tanks until the weight of the unit simultaneously loads the soil under the spudcans to a level equal to or exceeding anticipated spudcan loads forthe design storm condition. During the preload process, increasing soil loading usually causes the legs to penetrate deeper until the bearing capacity of the soil becomes equal to or greater than the spudcan loads. The preload process is complete when the spudcans have penetrated to a soilstratum with a bearing capacity sufficient to support the fully preloaded weight of the unit without further penetration. One of the main potential problems during preloading is a sudden uncontrolled leg penetration which can apply forces to the unit exceeding those imposed by the design storm.<\div>

۴Maximum wave force and run up on the curtain wall–pile breakwaters
اطلاعات انتشار: نهمین همایش بین المللی سواحل، بنادر و سازه های دریایی، سال
تعداد صفحات: ۱۱
A perforated wall breakwater consisting of a perforated front wall, a solid back wall and a waveabsorbing chamber between them was initially proposed by Jarlan (1961). As is well known, theperforated wall breakwater has two main advantages. One is to dissipate the incident wave energy and reduce the wave reflection from the breakwater, and the other is to reduce the wave force acting on the structure. The interaction of the water waves with perforated wall breakwaters have been studied for a longtime by different researchers. Most of the studies have focused on the reflection coefficient ofthe perforated wall breakwater. The horizontal force on the perforated wall structures has also been investigated by some researchers.In some instances, a permeable barrier, such as slotted vertical barrier made from timber planks, may be used. For example, this may be selected in an effort to reduce unwanted wave reflectionson the upwave face of the barrier. Thus the prediction of wave interaction with a permeable orslotted thin vertical barrier is also of interest. Classical inviscid solutions are available for a thin slotted vertical barrier extending from the free surface to the seabed {e.g., Lamb [4] and morerecently Martin and Dalrymple [5]}. However, these solutions do not account for the energy loss within the barrier due to viscous effects and therefore they overestimate wave transmission in comparison with the experimental results. An approximate solution was given by Wiegel (1961) in an attempt to include the energy loss within the barrier, but this was found to underestimate the wave transmission because the effectsof wave reflection were neglected. More generalized formulations that explicitly account for thewave energy absorption have been developed for wave interaction with permeable structures extending from the free surface to the seabed {e.g., Bennet et al. [6]; Kakuno and Liu [7]; Yu[8]}. Most such formulations assume that the velocity through the porous medium is proportionalto the pressure gradient, with a complex proportionality constant that accounts for possible phasedifferences between the velocity and pressure gradient. This description can be related to thephysics of the flow within the structure on the basis of frictional and inertial effects. Comparisonwith the experimental measurements of transmission and reflection coefficients has been carriedout for rows of vertical cylinders {e.g., Kakuno and Liu [7]} and slotted barriers {e.g., Bennet etal. [6}}, and these generally exhibit satisfactory agreement. However these works has not beenextended to partially submerged barriers.This paper outlines the numerical calculation of wave runup and wave forces on the upwave face of the curtain–wall breakwater (CBP) using circular piles. Numerical results compare well with available experimental measurements of the wave transmission, reflection coefficients andindicate that the numerical model is able to account adequately for the maximum wave force and wave run up. The effects of the porosity, relative draft of curtain–wall are discussed.<\div>

۵STUDY OF THE EFFECTS OF SEABED SOIL REMOLDING ON THEVERTICAL PENETRATION RESISTANCE OF OFFSHORE PIPELINESUNDER STATIC LOADS
اطلاعات انتشار: یازدهمین همایش بین المللی سواحل، بنادر و سازه های دریایی، سال
تعداد صفحات: ۴
Nowadays, due to the development of offshore oil and gas reservoirs, pipelines are widely usedas a simple and safe method for transferring hydrocarbon products from one place to another<\div>
نمایش نتایج ۱ تا ۵ از میان ۵ نتیجه