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Erosion Sediment Control
Published in M. Sengupta, Environmental Impacts of Mining, 2018
Two types of bank protection structures are used: revetments and deflectors. Revetments comprise a wide variety of both rigid and flexible structures which are used as erosion-resistant facing on streambanks and lakeshores. The flexible type of structure is preferred and is generally more economical for streambank protection. Flexible revetments such as riprap, fabriform mats, gabions, etc., have advantage over rigid revetments such as asphalt paving or monolithic concrete, because they are capable of adjusting to minor changes in foundation conditions without losing their integrity. The most common type of flexible revetment used for streambank protection is randomly placed stone riprap, composed of loose stone placed on sand/gravel filter and/or filter cloth. Other types of flexible revetments, although not nearly as flexible as stone riprap, are gabions, fabriform mats, interlocking concrete blocks, and steel or concrete tetrahedrons. Selection of the revetment type for particular bank condition will depend upon the strength requirements, length of required service, and aesthetic factors. In areas in which the extreme durability of randomly placed stone riprap is unnecessary or in areas in which rock is not readily available, other types of revetments may be necessary, considering also fish and wildlife habitat or aesthetic reasons.
Marine action and control
Published in F.G. Bell, Geological Hazards, 1999
A revetment affords an embankment protection against wave erosion (Thorn and Simmons, 1971). Stone is used most commonly for revetment work, although concrete is also employed. The chief factor involved in the design of a stone revetment is the selection of stone size, it being important to guard against erosion between stones (Figure 7.15). Consequently, coarse rip-rap must be isolated from the earth embankment by one or more courses of filter stone. Stone pitching is an ancient form of embankment protection, consisting of stone properly placed on the clay face of the wall and keyed firmly into place. Revetments of this type are flexible and have proved very satisfactory in the past. Flexibility is an important requirement of revetment since slow settlement is likely to occur in a clay embankment. As an alternative to keying, stones may be grouted or asphalt-jointed.
Ash Disposal versus Reuse
Published in Frank R. Spellman, Incinerating Biosolids, 2020
The cost of each revetment was about $150 per linear foot of shoreline including materials and labor. The cost of a comparable stone revetment at each location would be about $125 per linear foot of shore (Hardaway et al., 1994). It should be pointed out that this was a demonstration project and additional costs were involved for the manufacturing process required to produce the Seabee block. The costs would be more competitive with stone as longer stretches of shoreline are treated (i.e., production in large volume equals reduced costs).
Accuracy of visual inspection of flood defences
Published in Structure and Infrastructure Engineering, 2023
W. J. Klerk, W. Kanning, M. Kok, J. Bronsveld, A. R. M. Wolfert
Currently most risk-based assessments of flood defence safety assume that the flood defence is in good condition, and do not include the possibility of undetected defects and their potential effect on flood defence safety. While for instance the International Levee Handbook does note that inspections are not perfect, this is not translated to consequences for flood risk assessments (CIRIA, 2013). Assuming that existing (visual) inspection policies give a complete overview of defects will thus lead to an underestimation of actual flood risk. For instance, if the erosion resistance of a grass revetment is overestimated due to undetected damage, the actual flood risk might be higher than is estimated in typical flood risk assessments. As, based on the literature, it is likely that at least a part of the damaged areas remains undetected for some time, including such factors in risk assessments will improve risk estimates. Insight in the accuracy of visual flood defence inspection, and identifying factors that cause damages to remain undetected, can aid in defining targeted actions to improve inspection quality. Examples are improving task definitions, targeted training of inspectors, and improvement of inspection guidelines (See, Drury, Speed, Williams, & Khalandi, 2017). Such insights can help improve both assessment of existing and prediction of future performance (e.g. Quirk, Matos, Murphy, & Pakrashi, 2017; Ter Berg, Leontaris, van den Boomen, Spaan, & Wolfert, 2019). Obtaining estimates of flood defence inspection accuracy can therefore provide a basis for further improvement of such inspections, improve flood risk estimates, and improve flood protection performance.
A numerical model for river ice dynamics based on discrete element method
Published in Journal of Hydraulic Research, 2022
Biyao Zhai, Lu Liu, Hung Tao Shen, Shunying Ji
Bank protection of the Yellow River is of significant concern due to its soft soil and sparse vegetation. As shown in Fig. 19, the riprap revetment is commonly used to prevent bank failure and erosion due to the scouring by ice runs. The model simulated the force exerted by the ice run on the riverbank during ice transport. Figure 20 shows the calculated force distribution along the riverbanks. This showed the concave side of the bank experiences the highest force. The results obtained can provide a reference to determine the key locations that require protection and the amount of reinforcement required.
German guidelines for designing alternative bank protection measures
Published in Journal of Applied Water Engineering and Research, 2018
B. Söhngen, P. Fleischer, H. Liebenstein
In this context, the necessity and the extent of a bank protection have to be examined in the first instance based on technical aspects only by using the GBB (BAW 2010). It delivers design-relevant hydraulic loads, which can be compared to corresponding thresholds of the erosion resistance of the ten recommended technical-biological constructions, see Chapter 4 for details and the required thickness of a hypothetical riprap revetment to counteract the excess pore water pressures as explained before.