توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱USING MICRO PILES FOR LIQUEFACTION MITIGATION IN LOW COMPACTED SANDY SOILS FOR ONSHORE STRUCTURES , CASESTUDY: KOOHESTAK FISHERY HARBOR
نویسنده(ها): ، ،
اطلاعات انتشار: دهمین همایش بین المللی سواحل، بنادر و سازه های دریایی، سال
تعداد صفحات: ۱۴
Micro–piles are principally used as elements for foundation support to resist static and dynamic loading conditions, less frequently as in–situ reinforcements for slope and excavation stability andconstruction of onshore coastal structures in low consolidated sandy beds. The study was performedon Koohestak fishery harbour (Fisheries Organization, IFO), Hormozgan Province, IRAN. In this paper, using perforated micro–piles instead of steel piles were studied. Case study is located at 200km east Bandar Abbas and 45 km south coast Minab on the northern shore of Persian Gulf withgeographical coordinates equal to 260 8` N –570 1`E. According to the geotechnical tests and analysis, the basement has a significant liquefaction potential which could cause serious settlements in thefoundation of the wharf. The design of the micro piles has been done in three steps. First, structural design, the bearing capacity of the elements was determined. For the next step, geotechnical design, the bond strength of the micro pile was calculated. Finally, the punching shear control was performed. Furthermore, based on the field and laboratory tests, especially SPT test, the rectangular andtriangular shapes were considered for the micro piles arrangement under the basement. As a result ofthe design procedure, 180 micro–piles with 12 meter initial length were designed to be installed in the basement of this project instead of using steel piles. Using this method has several advantages. As construction advantages, the installation procedure causes minimal vibration and noise. Also, the construction time will decrease. From geotechnical point of view, using micro–piles in this project will lead to about 30% decrease in liquefaction in comparison with steel bars that have no effect on the soil properties. In addition, from economical point of view, about 15% will be saved by using micro piles instead of steel bars in this project.<\div>

۲Application of Geosynthetics in Construction of Static Rubble Mound Breakwaters; Case Study Sadra Omid Chabahar Shipyard complex
اطلاعات انتشار: نهمین همایش بین المللی سواحل، بنادر و سازه های دریایی، سال
تعداد صفحات: ۱۴
Construction of embankment and impoundments over soft soils is one of the most important problems in coastal engineering. Geosynthetic materials are installed beneath or between soillayers to improve the mechanical properties of soil layers by absorbing the tensile forces andminimizing deformation. Chabahar is located in south area of Iran and beside Oman Sea on the northern shore of the Persian gulf with geographical coordinates equal to 600 37` E –250 17`N. In this place, a new breakwater should be constructed. According to the investigations about the soiltype and strength parameters, the soil location is very soft. The calculations show the typical section of dike over this type of soil is not stable. In this research, effect of Geosynthetic materials as reinforcement in foundation of dike on strength and settlement of foundation soil isanalyzed. The other purposes of the research are to consider practicability of construction steeperslope and application of Geosynthetic materials as filter layer. The design method for thisapplication is fully covered by BS8006:1995. This British Standard contains guidelines and recommendations for the application of reinforcement technique to soils, as fill or in situ, and to other fills. For analyzing stability of the slope, RESSA® and Plaxis programs are implemented.The results of calculations show application a layer of Sequgrid® 400\40 as reinforcement offoundation will result in: 1) Increasing strength parameters of soft soil and sustainable breakwater; 2) Decreasing foundation settlement; 3) Practicability of steeper slope. Also for separation of embankment from the soft soil, a layer of Terrafix® R 813 should be installed under the Sequgrid®, and a layer of Terrafix® R 609 can also be used instead soil filter layer in the embankment body to reduce the material usage.<\div>

۳Comparison Of Dam Break Hydraulic Analyses Using Numerical Model
نویسنده(ها): ، ،
اطلاعات انتشار: هشتمین کنگره ملی مهندسی عمران، سال
تعداد صفحات: ۹
Dams are an important part of this nation’s infrastructure. When populations at risk are located close to a dam, it is important to accurately predict the breach outflow hydrograph and its timing relative to events in the failure process that could trigger the start of evacuation efforts. Surge waves resulting from dam breaks have beenresponsible for numerous losses of life. Sudden reservoir drawdown caused by partial breach of a dam can createa surge within the reservoir. Positive and negative surges are generally observed in open channels. Positive surges that occur due to tidal origins are referred to as tidal bores. A positive surge occurs when a sudden change in flow leads to an increase of the water depth, while a negative surge occurs due to a sudden decrease in water depth. Anegative surge is an unsteady flow characterised by a decrease in water depth. Negative surges can occurdownstream of a control structure when the discharge is reduced. They also occur upstream of a control structure that is opened rapidly or The failure time is very low. For a stationary observer the negative surge appears to be a gentle lowering of the free surface. The Hec–ras model based on the linearized implicit finite–difference modelwhich based on the De St. Venant equations. When the surge occurs, the De St. Venant differential equationsare not valid in the neighborhood of the surge. In general, a numerical analysis of unsteady flow in a reservoir has to be able to deal either with zones of supercritical and subcritical flow separated by a discontinuity or with flows that are entirely subcritical. In most cases the partial differential equations cannot be solved by analytical methods, but they may be solved to obtain approximate solutions by numerical methods. So a mathematicalmodel with special surge equations is incorporated in the method of characteristics models. Thus, the models candescribe closely the wave formations in the reservoir. They can establish the time and place of surge generation, and they can track the surge whether it is propagating under subcritical, supercritical, or mixed flow conditions. it is very important to understand wave propagation in a reservoir caused by a dam–break. when the failure time isvery low, So a steep negative wave may be formed. In this case was used software Fortran 90 to solveapproximate solutions .According to This paper provides the mathematical and analytical methods and numerical model using Hec–Ras to simulate dam break furthermore it used to predict breach outflow hydrographs .Unsteady flow modeling is often used in dam breach analysis due to the need to obtain more detailed or accurate results. Breach characteristics can be estimated in several ways which is describe the physical characteristics of a dambreach, use of those parameters within the unsteady flow routing model Hec–Ras , and the computation breachout flow hydrograph. The breach parameters will directly and substantially affect the estimate of the flows. Due to this illustrate the failure time is very low, So the negative surge occurs, However De St. Venant differential equations are not valid in the neighborhood of the surge. In order to evaluate the effective of negative wave on the outflow hydrograph. according to this, the outflow computed by the simplified model with approximate solutions based on Explicit Numerical method . The results of the Hec–Ras simulation, present that it was relatively closely to estimate peak breach discharges with approximate solutions.<\div>

۴Computational Fluid Dynamics Modeling Of Wave Run Up Over The Slope Of Breakwater Using Numerical Model
اطلاعات انتشار: دهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۱۰
Construction of embankment and impoundments over soft soils is one of the most important problems in coastal engineering. Chabahar is located in south area of Iran and beside Oman Sea on the northern shore of the Persian gulf with geographical coordinates equal to 600 37` E –250 17`N. In this place, a new breakwater should be constructed. According to the investigations on the breakwater constructions, the design parameters of the layers of breakwater should be calculated based on current breaking ,over topping and run up high .The design method for this application is fully covered by The Coastal Engineering Manual (CEM) assembles in a single source the current state–of–the–art in coastal engineering to provide appropriate guidance for application of techniques and methods to the solution of most coastal engineering problems. The CEM provides a standard for the formulation, design, and expected performance of a broad variety of coastal projects .The results of calculations show the top level of the armors was determined due to the wave run–up and overtopping conditions .An analysis of the different wave–structure interaction processes is performed, by simulation wave run–up over the breakwater using Ansys CFX .The Ansys results are compared with ACES software results which predicts run–up based on analytical solutions. Results of the two soft waves are in a good agreement and approach the same run up high results<\div>

۵Computational Fluid Dynamics Modeling Dam Break Using Numerical Model
اطلاعات انتشار: دهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۹
Dams are an important part of this nation’s infrastructure. When populations at risk are located close to a dam, it is important to accurately predict the breach outflow hydrograph and its timing relative to events in the failure process that could trigger the start of evacuation efforts. Surge waves resulting from dam breaks have been responsible for numerous losses of life. Sudden reservoir drawdown caused by partial breach of a dam can create a surge within the reservoir. Positive and negative surges are generally observed in open channels. Positive surges that occur due to tidal origins are referred to as tidal bores. A positive surge occurs when a sudden change in flow leads to an increase of the water depth, while a negative surge occurs due to a sudden decrease in water depth. A negative surge is an unsteady flow characterised by a decrease in water depth. Negative surges can occur downstream of a control structure when the discharge is reduced. They also occur upstream of a control structurethat is opened rapidly or The failure time is very low. For a stationary observer the negative surge appears to be a gentle lowering of the free surface. The Hec–ras model based on the linearized implicit finite–difference model which based on the De St. Venant equations. The various implicit methods of finite differences that have been developed, the Preissmann–type schemes. When the surge occurs, the De St. Venant differential equations are not valid in the neighborhood of the surge. In general, a numerical analysis of unsteady flow in a reservoir has to be able to deal either with zones of supercritical and subcritical flow separated by a discontinuity or with flows that are entirely subcritical. So In most cases the partial differential equations may be solved to obtain The Explicit MacCormack (MOC) model by Method of Characteristics in the neighborhood of the surge. Thus, the models can describe closely the wave formations in the reservoir. They can establish the time and place of surge generation, and they can track the surge whether it is propagating under subcritical, supercritical, or mixed flow conditions. it is very important to understand wave propagation in a reservoir caused by a dam–break. when the failure time is very low, a steep negative wave may be formed. In this case was used software Fortran 90 and write code to solve The Explicit McCormack model. According to This paper provides the Parametric Models methods and numerical model such as MacCormack Explicit scheme and Preissmann Implicit scheme using Hec–Ras tosimulate dam break furthermore it used to predict breach outflow hydrographs .Unsteady flow modeling is often used in dam breach analysis due to the need to obtain more detailed or accurate results. Breach characteristics can be estimated in several ways which is describe the physical characteristics of a dam breach, use of those parameters within the unsteady flow routing model Hec–Ras , and the computation breach out flow hydrograph. The breach parameters will directly and substantially affect the estimate of the flows. Due to this illustrate the failure time is very low, as a result the negative surge occurs, However De St. Venant differential equations are not valid in the neighborhood of the surge. In order to evaluate the effective of negative wave on the outflow hydrograph. according to this, the outflow computed by the simplified model with The explicit method of characteristics (MOC). The results of the Hec–Ras simulation, present that it was relatively closely to estimate peak breach discharges with The Explicit McCormack model.<\div>
نمایش نتایج ۱ تا ۵ از میان ۵ نتیجه