Study of Reflection of New Low-reflectivity Quay Wall

8/19/2019 Study of Reflection of New Low-reflectivity Quay Wall

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STUDY OF REFLECTION OF NEWLOW-REFLECTIVITY QUAY WALL

CAISSON

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Figure 1.- Construction o !"#e-$issi%"ting c&"'(ers) *"+ circu,"rce,,s "n$ *(+ $i"'on$ !ire cut.

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Ne! ,o!-reecti#it$esign

Figure /.- Ne! ,o!-reecti#itc"isson t%e.3/28/16


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The basic idea of the ulti&cell circuit schee *+i$! 2, is to connectcaisson cells in two di)erent directions to for cell circuits with theadequate len$th to attenuate the incident waves at the construction site!

The cell circuits ay be lon$ enou$h to e-ciently attenuate lon$ wavesand to optii.e caisson perforance under low&frequency incident

waves! Instead of caisson perforance bein$ conditioned by the width of the

anti&re#ective .one' which is "ed in ost cases' a caisson can bedesi$ned to be especially e-cient in reducin$ wave re#ection of a $ivenspectral bandwidth' includin$ very low&frequency waves

The ulticell circuits concept can be adapted to obtain the a"iu

e-ciency in wave re#ection reduction for specic caissons in a $ivenharbour .one!

It is necessary to take into consideration that incident waves on thecaissons' the re#ection of which ust be attenuated' have di)erentfrequencies in di)erent harbour areas!


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0YSICAL 2ODEL TESTS

Sall&scale physical e"perients were conducted in thewave #ue of the 0 to investi$ate the re#ectionbehavior of several perforated&wall breakwater caissonodels!

The 0 wave #ue is 3! eters lon$' 1!2 eters wideand 1!2 eters deep4 it is equipped with a piston wave$enerator with 5(5%S active wave absorption syste!

+i$! 3 and +i$! show the cross section and front view ofthe anti&re#ective caisson odel

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Figure 3.- Cross section o "nti-reecti#e c"issons teste$in !"#e u'e

*$i'ensionsin c'.+3/28/16


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Figure 4.- Front #ie! o ne! ,o!-reecti#it c"isson 'o$e, *sc",e 1536+

Figure

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Figure 6.- Lo!-reecti#it 'u,ti-ce,, circuit c"isson 'o$e,23

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ANALYSIS OF RESULTS

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This ethodolo$y has been used to select si$nicantvariables and to analy.e and copare results!

7i$hty percent of the data were randoly selected fortrainin$ and 2 for testin$!

It has been found that both 9/:1 and 9/:1c describedthe observed results satisfactorily' where 9 is the widthof anti&re#ective .one' :1 is the wave len$th in thebasin and :1c is the wave len$th inside the caisson cell!

+i$! 6 copares the re#ected ener$y percenta$e *7;,

observed and estiated by the 2 and >3

low&re#ectivity caissons


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Figure 7.- 8ER*9:L+ or c"issons 21) 2/ "n$ 23


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CONSTRUCTIONFEASI9ILITY

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The construction feasibility of window&type openin$s incaisson cells was tested at prototype scale withsatisfactory results usin$ the %?7S caisson productionfacility!

%aissons were anufactured' #oated&out' towed' sunkand placed in the


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Figure ;.- Se",e$ %ieces "n$ co#er %rotection orto!ing in '"nu"cturing c"isson %rocess.


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Figure 1


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CONCLUSIONS

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5 new concept of ulti&cell circuit schee isconsidered to be especially e)ective in reducin$low&frequency wave re#ection!

The basic idea of the ulti&cell circuit schee is to

connect caisson cells in two directions to createcircuits of su-cient len$th and also to optii.e the$iven response to low&frequency incident waves!

Instead of havin$ a caissonBs perforance

conditioned by the anti&re#ective .one width' "edin ost cases' caissons can be desi$ned to beespecially e-cient for a $iven spectral bandwidthincludin$ very&low&frequency waves!


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Study of Reflection of New Low-reflectivity Quay Wall

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