نتایج جستجو برای: local scour

تعداد نتایج: 533069  

2012
Sabita Madhvi Singh P. R. Maiti

Local scour around a cylindrical pier in a channel with an erodible bed or natural bed is a common problems in bridge or pile supported structure. The highly unsteady complex flow field around a circular pier produces scour hole mainly for the presence of vortices. The main mechanism that drives the formation and evolution of the scour hole around bridge pier is horse shoe vortex motion. In the...

2015
Arun Goel

Prediction of maximum local scour is necessary for the safety and economical design of the bridges. A number of equations have been developed over the years to predict local scour depth using laboratory data and a few pier equations have also been proposed using field data. Most of these equations are empirical in nature as indicated by the past publications. In this paper attempts have been ma...

Journal: :JSEA 2010
Seyed Rahman Homayoon Alireza Keshavarzi Reza Gazni

This paper outlines the application of the multi-layer perceptron artificial neural network (ANN), ordinary kriging (OK), and inverse distance weighting (IDW) models in the estimation of local scour depth around bridge piers. As part of this study, bridge piers were installed with bed sills at the bed of an experimental flume. Experimental tests were conducted under different flow conditions an...

2009
Abdelazim M. Negm Gamal M. Abdel-Aal Magid M. Elfiky Yasser A. Mohamed Govinda Rao

Many of the huge structures like New Esna, and New Nega Hammadi Barrages face a great harmful caused by local scour downstream (DS) their stilling basins. It is planned to redesign many of these structures to minimize these harmful impacts of the DS local scour. This research paper presents the results of an extensive experimental investigation on using an optimized submerged curved deflector t...

Journal: :آب و توسعه پایدار 0
حسین شریعتی سعید رضا خداشناس

scouring is the removal of sediment particles resulted from variations of flow pattern. local scour is considered among the reasons of instability and ultimately failure of bridges. during the past decades, different methods were proposed against local scour at bridge piers. these methods can be broadly classified into two categories: flow-altering and bed-armoring methods. each method can be c...

2006
Yung Bin Lin Kuo Chun Chang

Taiwan is located in the rim of the Pacific Ocean. The activities of the earthquake happen frequently, which threaten the safety of the bridge in the Taiwan Island. Besides, the severe floods resulted from the typhoon or storm events can cause great damages due to the bridge scouring. The steep-sloped rivers and sand mining problems in Taiwan accelerate the degradation of the riverbed. Scouring...

2007
Pierre Y. Julien

A theoretical investigation of local scour downstream of grade-control structures based on two-dimensional jet diffusion and particle stability is experimentally verified. Turbulent jet diffusion reduces fluid velocity near the bed particles and equilibrium scour is obtained when noncohesive bed particles cannot be removed from the scour hole. Equilibrium scour depth is written as a function of...

2017
Shi Liu Yi Yang Xiaobo Wu

Received: February 02, 2017 Revised: March 13, 2017 Accepted: May 19, 2017 Abstract: Introduction: Bridge scour is one of the major causes of bridge failure. Prediction of the maximum depth and shape of local scour plays an important role in bridge design and maintenance. In this paper, k-ε turbulent model combined with wall function was employed and complex flow fields are exhibited. The bed l...

Journal: :تحقیقات مهندسی کشاورزی 0
حسین حمیدی فر دانشجوی کارشناسی ارشد دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران محمدحسین امید دانشیار گروه مهندسی آبیاری و آبادانی دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران

the effect of grain size, tailwater depth and grain froude number on local scour caused by submerged horizontal jets issuing below a sluice gate was investigated. noncohesive sediments with two gradations downstream of a horizontal apron were used in the experiments. the experiments were carried out at different inflow froude numbers and a range of tailwater depth from low to high submergence. ...

Journal: :مهندسی عمران فردوسی 0
عبدا... اردشیر روح ا... چراغچی حجت کرمی

local scour around the abutment is of utmost importance in bridge failures. numerous methods such as riprap have been proposed to reduce the destructive effects of scouring; one of the ways to harness and reduce the local scour depth is installed protective collars around the abutment. in this paper effect of collar elevation (upper level, bed level and lower level), collar geometry and its siz...

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