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Anthropo-Footprints on Churni River
Published in Balai Chandra Das, Sandipan Ghosh, Aznarul Islam, Suvendu Roy, Anthropogeomorphology of Bhagirathi-Hooghly River System in India, 2020
Biplab Sarkar, Aznarul Islam, Balai Chandra Das
The contraction scouring appears when flow area of a river is reduced by the bridge and embankments (Figure 13.11a and b). The embankments force the overbank flow to run through the channel, and as a result, the average velocity and bed shear stress increase to remove more bed material from the constricted reach (Abid, 2017; Al-Shukur and Obeid, 2016; Gampathi, 2010; Ghorbani, 2008; Govindasamy, 2009; Kothyari, 2007; Khan et al, 2016; Laursen and Toch, 1956; Rahman and Haque, 2003; Saha et al., 2018). On the other side, Hoffmans and Verheji (1997) observed that the development of scouring around the bridge piers (local scouring) is one of the principal causes of bridge failure. When flow is interrupted by the intrusion of piers, velocity increases and vortices occur around the piers which, as a result, remove the bed material with the flow developing the local scouring. In the river Churni, the role of hydraulics and bridge in scouring development has been analysed thoroughly.
The experimental investigation of defects
Published in A. M. Sowden, The Maintenance of Brick and Stone Masonry Structures, 2020
The weather creates the most important aspects of a structure's environment, with water being the most unfriendly element. Much of the deterioration of the structural fabric has as its root cause the breakdown of the structure's waterproofing and drainage system, Once the water can permeate through the structure the way is open for damage caused by freeze-thaw, erosion, leaching out of the mortar and general reduction of the strength of the structural fabric. Rain can contain pollutants and ground water absorbs chemicals which can attack a structure by chemical action. An example of this is sulphate attack on cementitious materials like concrete and mortar. When a structure is exposed to flowing water, scouring can result. This is caused by the water alone to some extent, but mainly by the particles it carries with it.
Sediment Control in Rivers and Reservoirs
Published in Larry W. Mays, Optimal Control of Hydrosystems, 1997
Scouring (or degradation) on the other hand, threatens instream and bank structures like flood levees, bridge piers, as well as underground utility lines. Either way, if sedimentation processes are left unchecked or uncontrolled in the system, there could be serious economic consequences. Interestingly, under a given flood event or series of flood events, both aggradation and degradation phenomena occur side-by-side across the channel and simultaneously in the same river. Any bed change, however, as a result of sediment movements due to floods, is a sign of channel instability, and efforts must be pursued to minimize such instability in the channel. Because flood events are known to be the principal instigator of bed mobility, focus must be made on how such flood events could be altered or modified into a series of events that permits the least amount of bed changes in the river.
Local scour at abutment under vertical and side suction seepage
Published in Journal of Hydraulic Research, 2023
Panchali Chakraborty, Abdul K. Barbhuiya
Scouring is a physical event resulting from the erosive action of moving water that removes materials from the bed and banks of the river (Barbhuiya & Dey, 2004). Hydraulic structures (bridge abutments or piers) cause local disturbances in the flow by increasing mean velocity and/or turbulence intensity, thereby increasing local transport capacity, resulting in local scour around the structure. In various scenarios, the scour hole formation may increase to a magnitude that becomes a threat to the bridge foundations, resulting severe damage to the entire structure. A precise scour depth prediction is necessary for bridge safety as underestimation may causes structure failure, and overestimation will increase building costs (Melville & Coleman, 2000). Several investigators have made diverse attempts to analyse the scour development process and prediction of scour depth at abutments (Ahmed & Rajaratnam, 2000; Barbhuiya & Dey, 2004 Coleman et al., 2003; Kumcu et al., 2007;; Melville, 1997; Mohammadpour et al., 2013) and piers (Chiew, 2004; Das et al., 2014; Dey, 1997; Dey & Raikar, 2007; Diab et al., 2010; Kumcu et al., 2014; Vijayasree et al., 2019).
Three-dimensional numerical simulations of local scouring around bridge piers
Published in Journal of Hydraulic Research, 2018
Yafei Jia, Mustafa Altinakar, M. Sukru Guney
Local scouring is a common threat to in-stream structures, such as bridge piers and abutments that are constructed in alluvial rivers, as it often results in bridge damage or failures. The hydrodynamic force of the approach flow is counterbalanced by the pier standing in the way. A special flow pattern and additional turbulent fluctuations are generated, providing excess erosion power, and thus creating a deep scouring hole around the structure. A large number of laboratory experiments, field measurements, and numerical simulations have greatly improved the understanding of the physical mechanisms of scouring and have resulted in development of semi-empirical equations and numerical models for predicting the depth of local scouring under a variety of flow, sediment and pier conditions.
Estimation and interpretation of equilibrium scour depth around circular bridge piers by using optimized XGBoost and SHAP
Published in Engineering Applications of Computational Fluid Mechanics, 2023
Nasrin Eini, Sayed M. Bateni, Changhyun Jun, Essam Heggy, Shahab S. Band
Scouring around bridge piers is a notable driving factor of bridge collapses (Wardhana & Hadipriono, 2003; Wang et al., 2017). According to the US Department of Transportation, scouring led to the damage of 17 bridges in New York and New England during the flood in 1987 (Richardson & Davis, 2001). The Federal Highway Administration defines scouring as the process in which the streambed sediments are eroded and removed from bridges by the water flowing over the bed (Mueller & Wagner, 2005). Different bed materials undergo various levels of scouring, leading to different scour rates. For example, non-cohesive materials such as sand and gravel may erode over a few hours, but more time is required for cohesive bed materials to be eroded (Richardson & Davis, 2001).