Further studies of incipient motion and shear stress on local scour around bridge abutment under ice cover

2014 ◽  
Vol 41 (10) ◽  
pp. 892-899 ◽  
Author(s):  
Peng Wu ◽  
Faye Hirshfield ◽  
Jueyi Sui
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Shear Stress ◽  
Open Channel ◽  
Ice Cover ◽  
Scour Depth ◽  
Incipient Motion ◽  
Clear Water ◽  
Bridge Abutments ◽  
Bridge Abutment

An experimental study was conducted to investigate the scour development around bridge abutments under ice cover with non-uniform natural sands. Two abutments and three non-uniform sediments were used in the research. The mechanism of incipient motion for non-uniform sediments under ice cover was analyzed. By introducing scour angles around two abutments, a relationship between maximum scour depth and velocity was established for clear-water scour under ice cover. Dimensionless shear stress was also calculated and compared with shear Reynolds number for non-uniform sediments. The maximum scour depth and dimensionless shear stress were investigated under both open channel, smooth cover and rough covered conditions. Results show that around the square abutment, the scour angle is smaller than that of the semi-circular abutment. For clear water scour, the maximum scour depth increases due to the presence of ice cover.

Temporal scour development at bridge abutments with a collar

2007 ◽  
Vol 34 (4) ◽  
pp. 549-556 ◽  
Author(s):  
Şerife Yurdagül Kumcu ◽  
Mustafa Gögüş ◽  
Mehmet Ali Kökpinar
Keyword(s):  
Temporal Variation ◽  
Vertical Wall ◽  
Scour Depth ◽  
Clear Water ◽  
Flow Conditions ◽  
Bridge Abutments ◽  
Time Period ◽  
Bridge Abutment ◽  
Laboratory Flume ◽  
Sediment Particles

This study investigated the reduction of scour around a vertical-wall bridge abutment using rectangular collars for clear-water flow conditions over uniform sediment particles in a laboratory flume. Collars of different sizes and at different elevations were tested to determine the temporal variation of scour depth around the bridge abutment. The development of scour around the abutments with and without a collar for a time period of 6 h was studied, and observed scour depths were compared. Experimental results showed that, in addition to protecting the abutments against erosion, the addition of a collar is effective in reducing the rate of temporal scour development. A comparison of the present results with those from previous studies revealed that the effectiveness of a collar increases with a decrease in the elevation of the collar and an increase in the width of the collar.Key words: bridge abutment, collar, experimentation, hydraulics, scour, temporal variation.

Clear-Water Scour around Bridge Abutments under Backwater Conditions

1996 ◽  
Vol 1523 (1) ◽  
pp. 196-202 ◽  
Author(s):  
Terry W. Sturm ◽  
Aftab Sadiq
Keyword(s):  
Flow Distribution ◽  
Scour Depth ◽  
Clear Water ◽  
Bridge Abutments ◽  
Bridge Abutment ◽  
Rectangular Channels ◽  
Contraction Ratio ◽  
Bridge Approach ◽  
Contraction Scour ◽  
Abutment Scour

An experimental study was conducted of the depth of clear-water scour around the end of a square-edged bridge abutment terminating in the floodplain of a compound channel. The study's purpose was to improve current techniques of abutment scour prediction, which are based primarily on laboratory studies in rectangular channels. It is indicated that a discharge contraction ratio arising from a theoretical contraction scour analysis for equilibrium conditions can be used for explaining the effect of flow distribution on the local abutment scour depth in the case where significant backwater occurs from bridge contraction. The use of reference values of approach flow depth and velocity in the floodplain for undisturbed conditions without the bridge is shown to collapse experimental results for scour depth in both the case of a contraction with negligible backwater, and the case of a contraction with significant backwater in the bridge approach section.

Experimental study of clear-water contraction scour

2020 ◽  
Vol 20 (3) ◽  
pp. 943-952 ◽  
Author(s):  
Ravindra Kumar Singh ◽  
Manish Pandey ◽  
Jaan H. Pu ◽  
Srinivas Pasupuleti ◽  
Vasanta G. Kumar Villuri
Keyword(s):  
Experimental Study ◽  
Reasonable Agreement ◽  
Time Dependent ◽  
Scour Depth ◽  
Clear Water ◽  
Equilibrium Conditions ◽  
Bridge Abutment ◽  
Water Conditions ◽  
Contraction Scour ◽  
Equilibrium Scour Depth

Abstract In this paper, experimental results of clear-water scour on a sand bed under short contractions were studied. Sequences of test runs were performed under clear-water conditions for three different contraction ratios. The outcomes of the experiments were employed to define the effects of various parameters on equilibrium scour depth under clear-water scour conditions. In this work, the precision of three maximum scour depth equations was tested from previous studies for contraction scour cases. Two new analytical equations were proposed to calculate time-dependent scour depth and maximum scour at equilibrium conditions, respectively, from the study. The proposed equations were validated using measurements from the present study as well as from previous literature, and the equations show a reasonable agreement between measured and computed values of scour depth under clear-water conditions in short contraction. The presented equations can be used for studying protection of the submerged portion at a bridge abutment or any similar structure.

Effect of Reynolds Number on Local Scour Around a Monopile in Steady Current

2019 ◽  
Author(s):  
Xiaofan Lou ◽  
Kaibing Zhang ◽  
Zhenhong Chen
Keyword(s):  
Reynolds Number ◽  
Time Scale ◽  
Time History ◽  
Local Scour ◽  
Circular Cylinders ◽  
Scour Depth ◽  
Clear Water ◽  
Number Range ◽  
Steady Current ◽  
Equilibrium Scour Depth

Abstract The effect of Reynolds number (Re) on the local scour around a monopile encountering steady current was investigated experimentally in a water flume. The experiment was performed using circular cylinders with different diameters under two different freestream velocities, covering both clear-water and live-bed scours and a Reynolds number range of approximately 9,000–60,000. The time-series of the scour depth was recorded during the whole scour process and the scour pit was scanned after the scour process reached equilibrium. Results are presented in terms of the equilibrium scour depth, the time-scale of the scour process and the three-dimensional scour profile at different Reynolds numbers. For both clear-water and live-bed scours, the time history of the scour process indicate that the time-scale becomes larger as Re increases. It is also found that the normalized equilibrium scour depth, as well as the normalized scour radius, decrease with the increasing Re. An empirical equation of the equilibrium scour depth is derived as a function of Reynolds number based on the experimental results so as to better account for Re effect in the scour design.

scholarly journals ANFIS approach to the scour depth prediction at a bridge abutment

2010 ◽  
Vol 12 (4) ◽  
pp. 474-485 ◽  
Author(s):  
Mohammad Muzzammil
Keyword(s):  
Fuzzy Inference ◽  
Accurate Estimation ◽  
Scour Depth ◽  
Bridge Abutments ◽  
Anfis Model ◽  
Inference System ◽  
Model Studies ◽  
Depth Prediction ◽  
Bridge Abutment ◽  
Conventional Regression

An accurate estimation of the maximum possible scour depth at bridge abutments is of paramount importance in decision-making for the safe abutment foundation depth and also for the degree of scour counter-measure to be implemented against excessive scouring. Despite analysis of innumerable prototype and hydraulic model studies in the past, the scour depth prediction at the bridge abutments has remained inconclusive. This paper presents an alternative to the conventional regression model (RM) in the form of an adaptive network-based fuzzy inference system (ANFIS) modelling. The performance of ANFIS over RM and artificial neural networks (ANNs) is assessed here. It was found that the ANFIS model performed best among of these methods. The causative variables in raw form result in a more accurate prediction of the scour depth than that of their grouped form.

scholarly journals Condition for the Incipient Motion of Non-Cohesive Particles Due to Laminar Flows of Power-Law Fluids in Closed Conduits

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1295
Author(s):  
Aldo Tamburrino ◽  
Cristóbal Traslaviña
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Power Law ◽  
Open Channel ◽  
Laminar Flows ◽  
Threshold Condition ◽  
Incipient Motion ◽  
Power Law Fluid ◽  
Power Law Fluids ◽  
Cohesive Particles

The results of an experimental study on the condition of incipient transport of non-cohesive particles due to the flow of a power-law fluid in a rectangular pipe are presented in this article. The pipe can change its inclination, and experiments were carried out with positive and negative slopes. From a dimensional analysis, the parameters that define the condition of incipient motion were found and validated with experimental data. Thus, the threshold condition is well defined by a particle Reynolds number and a Galileo number, properly modified to take into account the power-law rheology of the fluid. The experimental data are also presented in a standard Shields diagram, including the data obtained in other studies carried out in open-channel laminar flows of Newtonian and power-law fluids.

scholarly journals Experimental Study of Inclined Bridge Pier Scouring

2020 ◽  
Vol 39 (4) ◽  
pp. 859-870
Author(s):  
Fakhar Muhammad Abbas ◽  
Usman Ali Naeem ◽  
Usman Ghani ◽  
Amina Khan ◽  
Talat Farid Ahmad
Keyword(s):  
Experimental Study ◽  
Inverse Relationship ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Scour Depth ◽  
Clear Water ◽  
Lower Strength ◽  
Flow Rates ◽  
Laboratory Flume ◽  
Horseshoe Vortices

The bridges are one of important structures in any country. The failure of bridges occurs due to many factors including design flaws and manufacturing construction errors. Among all imperfections scouring around the pier is the most detrimental. So, the estimation of local scouring around a bridge pier is of fundamental importance for the safe design of bridges. Although numerous researches have been done on local scouring around a single bridge pier. The present study investigates the effect of angle of inclination of dual bridge pier configuration on local scouring around bridge piers. Principally rectangular shaped dual bridge piers were installed in sand bed of laboratory flume at angle of inclination of 0°,7°,12°,15° and 19° with vertical respectively. Three different flow rates 9, 14 and 18L/sec were considered during each trial. The duration of each trial was kept around 2 hours. The scour depth was measured separately around both piers with the help of point gauge under clear water condition. The value of scour depth around upstream pier was larger as compared to downstream pier because of the lower strength of horseshoe vortices around downstream pier. From the experimental results, it can be concluded that there is an inverse relationship between the angle of inclination and scour depth, an increase in the angle of inclination leads to decrease in scour depth around both piers. The value of scour depth was maximum when piers were at 0° and minimum at 19°. It was also found that scour depth increases with the increase in flow rate.

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