نتایج جستجو برای: scour reduction
تعداد نتایج: 493198 فیلتر نتایج به سال:
Observations of bridge abutment scour lead to a practical new approach for estimating realistic scour IIHR-Hydroscience and Engineering depths at bridge abutments. Prior design approaches usually led to unrealistically deep estimates of abutment scour depth. The observations presented stem from flume experiments conducted with abutments with approach embankments subject to a range of erodibilit...
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...
The paper describes the range of scour types that may occur at bridge abutments, and addresses the extensive attendant difficulties confronting accurate estimation of abutment-scour depth. The difficulties, which include similitude aspects of laboratory experiments on scour at bridge abutments, complicate the development of reliable scour-estimation relationships. In a practical sense, the diff...
The evolution of bridge pier scour is very important for bridge safety warning and assessment. During typhoon seasons in Taiwan, the torrential river flow often causes scour monitoring instruments to fail in their attempt to measure the temporal variations of pier scour depths. To better understand the scouring phenomenon during a large flood event, this study proposes a fast and reliable metho...
scoure is the removal of particle sediment which results variation of flow pattern. local scour is considered as one of the reasons of instability and ultimately failure of bridges.therefore, proposing some controlling methods to reduce this phenomenon is essential. in the study, effects of two types of squar and circular collar on a single cylindrical model have been investigated. in the next ...
A reliable prognostics framework is essential to prevent catastrophic failure of bridges due to scour. In the U.S., scour accounts for almost 60% of bridge failures. Currently available techniques in the literature for predicting scour are mostly based on empirical equations and deterministic regression models, like Neural Networks and Support Vector Machines, and do not predict the evolution o...
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...
Improved understanding of scour and sedimentation processes near and at highway bridges is dependant on collecting reliable field data. Field data collection programs, however, have been hindered by inadequacies in instrumentation and measurement technologies. Through a coordinated program of research, the Federal Highway Administration (FHWA), State Highway Agencies (SHAs), National Cooperativ...
Experimental studies to investigate the depth of the scour conducted at a side-weir intersection located at the 180 curved flume which located Hydraulic Laboratory of Yıldız Technical University, Istanbul, Turkey. Side weirs were located at the middle of the straight part of the main channel. Three different lengths (25, 40 and 50 cm) and three different weir crest height (7, 10 and 12 cm) of t...
The use of slot through a pier is a new method proposed to control local scour at bridge piers. In this study, control of local scour at bridge pier is studied using 20 pier models under clear water conditions. The models consist of one circular pier without slot, three round-nosed piers without slot, and 16 piers with slot. Two slot lengths were chosen (yl=b and yl=2b, where y1 is the length o...
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