Australian Jurnal f Basic and Applied Sciences, 3(4): 3190-3205, 2009 ISSN 1991-8178 Implementatin f Spur Dikes t Reduce Bank Ersin f Temprary Diversin Channels During Barrages Cnstructin 1 2 3 4 Ali Talaat, Karima Attia, Gamal Elsaeed, Mhammad Ibraheem 1 Department f Hydraulics and Irrigatin, Ain Shams University Department f Hydraulics and Irrigatin, Nile Research Institute, Natinal Water Research Center. 3 Department f Civil Engineering, Faculty f Engineering, Shbra, Banha University. 4 Department f Civil Engineering, Faculty f Engineering, Shbra, Banha University. 2 Abstract: This study was initiated t intrduce nn-submerged spur dikes as training structures t reduce ersin at the ppsite bank t diversin channel at Naga Hammadi barrage thrugh minimizing the velcity values near the banks. The length f the bank t be prtected is 450m. The width f diversin channel is 172m; hwever the average channel width at the regin under study is 450m. A tw dimensinal mathematical mdel were used t simulate many cases. T assure mdel validity, experimental results were used fr verificatin. The mdel simulated lngitudinal and transverse velcities as well as the spur wrking length. A financial ecnmic evaluatin as a functin f grin length is intrduced t help in selecting the ptimum grup with minimum cst. Eighteen runs (18) were executed where three (3) effective parameters were tested. These parameters were the cntractin rati, which is defined as the spur length t the channel width (L/B), the spur rientatin angle; and the spur spacing. The cntractin rati was varied between 0.1 and 0.2 while the used O O O rientatin angle are 60, 90 and 120 and the spacing was 2, 4, and 7 times as much as the spur length. The measurements cvered 60 grid pints alng fur lngitudinal lines (A, B, C, and D) crssed by 15 lateral crss sectins. The study cncluded that the maximum spur wrking length is ccurred with repelling spurs f 120 with a 0.2 cntractin rati at 2L r 4L spacing. On the ther hand, 7L spacing prduced the minimum wrking length in additin t its discntinuity. It was als fund that the wrking length is inversely prprtinal t the spur spacing but it is directly prprtinal t the spur length fr a fixed rientatin angle and spacing. The maximum and minimum values f lngitudinal velcity ccurred in the case f using a spur with an rientatin angle f 90 0 with a cntractin rati f 0.2. It was als nticed that changing the spur length, spacing, and rientatin angles did nt affect the maximum transverse velcities. Fr the tested cases, the maximum and minimum transverse velcities are lcated at the middle third f the channel. There is a clear similarity between the lngitudinal velcity in case f implementing repelling and straight spurs. Fr fixed spur length and spacing, using a grup f spurs at any rientatin angle, bth lngitudinal and transverse velcities decrease at the different crss sectins in the vicinity f the bank by 50% and 20%, respectively. Using a grup f 10% cntractin rati length presents mre ecnmic slutin frm the view f cst evaluatin when cmpared t 20% cntractin rati length. The study recmmended that 4 spur riented at 60 with 10% cntractin rati length and spacing f 4 times spur length can be used t prtect the attacked 450m at the bank facing the temprary diversin channel, while the repelling and straight types spur with 0.2 cntractin rati culd be implemented t prduce a deep channel. The scur assciated t spurs existence is discussed in a separate paper. Key wrds: Oriented Spur dike, mathematical mdel, velcity cmpnents, and wrking length. INTRODUCTION In rder t cnstruct a regulating structure like a barrage, a temprary artificial channel f smaller width is established after which cffer dams r diaphragm walls are cnstructed t dewater the cnstructin site t allw the wrkers and equipments t perate at the ftings and the main skeletn f the barrage. After the clsure f the cnstructin site, the full surge f water way is diverted t the artificial channel. On the ther hand, after pening the diversin channel the flw decelerates at the inlet due t the gradual cntractin. Hwever this phenmenn is reversed at the utlet due t the gradual enlargement. Cnsequently, the flw Crrespnding Authr: Gamal Elsaeed, Departmentf Civil Engineering, Faculty f Engineering, Shbra,Banha University 3190
exits the diversin channel with high velcity t strike the ppsite bank f the diversin channel thus causing its ersin. The implementatin f spur dikes t minimize the impacts n the ppsite bank f the diversin channel is investigated in this study. The spurs may be defined as a structure extending utward frm the bank f a stream fr the purpses f bank prtectin by deflecting the main current away frm critical znes (Klingeman, P.C., S.M. Kehe, 1984). This research was thus initiated in rder t define the ptimum grup f spurs that minimizing the bank ersin prblem. Many parameters are invlved t define the ptimum grup, the spur length, spacing, and rientatin angles. The spur implementatins cver bank length f 450 m, the number f spurs depends n the invlved parameters especially spur length and spacing. The effect f these parameters n the flw pattern and velcities in the diversin channels is studied. A tw dimensinal finite element mathematical mdel was develped by Mlinas and Hafez (2000) is used in this study. Fig. 1: General Layut Study Cases: A number f runs were simulated using the mathematical mdel; ne f which represented the flw pattern withut any spurs. This run was used as a reference t allcate the hydraulic perfrmance f spur dike implementatin at the ppsite bank f the diversin channel. The runs names are frmulated as spacing, functin f spur type, and cntractin rati. Fr example, 2A 10 means that the spur spacing is equal t 2L at O a 60 (attracting spur) with 10% cntractin rati, and 4S 20 means that the spur spacing is equal t 4L at a O O 90 (straight spur) with 20% cntractin rati, while 7R 10 means that the spur spacing is equal t 7L at a 120 (repelling spur) with 10% cntractin rati. Mrever, the spur lengths crrespnding t 10% and 20% cntractin rati are 45m and 90m respectively, as the average channel width is 450. It shuld be mentined that in all the tested cases the grup f grins cvered a channel length f 450m. This was achieved by changing the number f grins t fit the assigned 450m accrding t spur length and spacing. Table 1 shws the number f grins used fr each run and all ther details related t spur length, spacing, cntractin ratis and rientatin angles. 3191
Table 1: The Study Simulated Cases Run Name L/B Number f Grins Angle f Orientatin Spur Name 0 2A10 0.10 6 60 Attracting 4A10 0.10 4 7A10 0.10 3 2A20 0.20 4 4A20 0.20 3 7A20 0.20 2 0 2S10 0.10 6 90 Straight 4S10 0.10 4 7S10 0.10 3 2S20 0.20 4 4S20 0.20 3 7S20 0.20 2 0 2R10 0.10 6 120 Repelling 4R10 0.10 4 7R10 0.10 3 2R20 0.20 4 4R20 0.20 3 7R 0.20 2 20 MATERIALS AND METHODS Mathematical Mdel: The develped mdel gverning differential equatins are in the Cartesian X-Y crdinates, alng and acrss the main flw directin, respectively. On the ther hand, the Navier Stkes equatins are used t describe mtin. The fluid is assumed t be incmpressible and fllws a Newtnian shear stress law, whereby, viscus frce is linearly related t the rate f strain. In the mdel, the hydrdynamics gverning equatins are the equatins f cnservatin f mass and mmentum. Cnservatin f mass equatin takes the frm f the cntinuity equatin while Newtn s equatins f mtin in tw dimensins express the cnservatin f mmentum. The cntinuity equatin is given as: (1) The mmentum equatin in the lngitudinal (X) directin is (2) The mmentum equatin in the lateral (Y) directin is (3) Where U = Lngitudinal surface velcity, V = Transverse surface velcity, P = Mean pressure, n e = Kinematics eddy viscsity, F x = Bdy frce in X directin, F y = Bdy frce in Y directin, g = Gravity acceleratin, q = Average water surface slpe, r = Fluid density, ô fx = Turbulent frictinal stresses in X- directin, ô = Turbulent frictinal stresses in Y-directin. fy The assumptins used in the hydrdynamic mdel are: The density is assumed t be cnstant (incmpressible fluid). 3 Flw cnditins are cnstant (discharge=2900m /s). The turbulent viscsity varies with the velcity gradient. Tw-dimensinal surface analysis. Free surface as a rigid lid. Pressure is cnsidered t be hydrstatic. Wind stresses are neglected. 3192
It shuld be mentined that cmplete details abut numerical slutin f the mdel gverning equatins, the bundary cnditins and the wrking flw chart is presented in Ebraheem (2005). List f Symbls: The fllwing symbls are used in this paper: L = Spur length [m] U = Lngitudinal surface velcity [m/s] V = Transverse surface velcity [m/s] 2 P = Mean pressure [kg/m ] 2 n e = Kinematics eddy viscsity [m /s] F x = Bdy frce in X directin = g sin è [kg.m/s 2 ] F y = Bdy frce in Y directin = 0.0 [kg.m/s 2 ] g = acceleratin due t gravity [m/s 2 ] S= spacing between spurs [m] q = Average water surface slpe [degrees] 3 r = Fluid density [kg/m ] 2 ô fx = Turbulent frictinal stresses in X-directin [kg/m ] 2 ô = Turbulent frictinal stresses in Y-directin [kg/m ] fy Mdel Testing, Validity and Verificatin: T verify the effectiveness f the numerical mdel fr flw simulatin, a previus experimental study, carried ut in the Hydraulics Research Institute (HRI) Ministry f Water Resurces and Irrigatin, Egypt fr Naga Hammadi Barrage, is used. A cmparisn between the numerical and physical results was achieved at tw crss sectins ut f ten (crss sectin 6 and 7, at 50 m and 51.6 m respectively), frm the experiment inlet, Figure 2. These 2 sectins represent sectins at 1500m and 1550m, respectively, in the field (prttype). 3 The results are presented fr a discharge f 1500m /s. The figure indicates gd agreement between the mdel results and the experiment data. This insures the capability f the current mdel t reprduce cnfident results. Fig. 2: Testing the Validity f the Used 2-D Numerical Mdel 3193
RESULTS AND DISCUSSION The fllwing sectins shw the results f the several executed simulatins. The Wrking Length: The spur wrking length is defined as the spur influence length which is extended upstream and dwnstream the spur lcatin. T investigate the wrking length by the aid f velcity vectrs, a finite element mesh was created. It cnsisted f mre than 7200 measuring ndal which requires a lng time in running the mdel. Figure 3 shws a part f the created mesh. Fig. 3: Part f the Created Finite Element Mesh The wrking length fr a grup f spurs is the summatin f bth separatin pint and reattachment lengths. Using a grup f spurs may perfrm a cntinuus r separated wrking length. The cntinuus is the mst favrable as it prvides a week regin f flw in frnt f the bank that shuld be prtected. This is shwn in Figures 4 (a, b, and c) where the arrws define the velcity vectrs in the channel. Fig. 4(a): Flw Pattern arund Attracting Type Spur 3194
Fig. 4(b): Flw Pattern arund Straight Type Spur Fig. 4(c): Flw Pattern arund Repelling Type Spur Table 2 summarizes the ttal wrking length fr the different simulated cases. Frm the table it culd be nticed that the maximum wrking length was btained in case f implementing repelling spurs f 120 with 0.2 cntractin rati and 2L r 4L spacing. It culd als be nticed that such spurs create a separatin pint length at the upstream in additin t the reattachment length at the dwnstream (which are the tw cmpnents f wrking length). This agreed with what was cncluded by Ebraheem (2005) and Attia (2006). It was als nticed that the wrking length is inversely prprtinal t the spacing between spurs. Fr fixed rientatin angle and spacing, the wrking length is directly prprtinal t the spur length. The abve table illustrates that the wrking length was discntinuus, fr all the simulated cases f spurs with spacing f 7L at any rientatin angle and cntractin rati. Frm Table 2 it is nticed that the ptimum grups fr bank prtectin are 2A and 2S as they present the lngest wrking length. 10 10 Velcities: The imprtance f velcity in defining the ptimum grup f spurs fr bank prtectin can nt be neglected. The velcity is cnsidered t be a fcal parameter fr flw characteristics which helps t indicate the psitins f scur and depsitin due t spurs existence. The velcity was measured at 60 lcatins distributed alng fur lines in the lngitudinal directin and at 15 crss sectins, 40m apart. It shuld be mentined that the lngitudinal lines (A and B) are distributed t cver the channel width in rder t define the flw pattern in the vicinity f spurs. As fr line C and D, they are used t define the behavir f the velcity at the middle f the channel and at the ppsite bank, respectively, Table 3 and Figure 4. It shuld be mentined that line (A) is lcated prir t grin tip by 5m and 50m fr grup with 10% and 20% cntractin rati respectively. Hwever line (B) is lcated prir t grin tip by 10m nly fr the grup f 20% cntractin rati. 3195
Table 2: The Wrking Length and Its Cntinuity Run Name Wrking Length (m) Wrking Length Functin Cntinuity f Wrking Length in Length (L) Basic ----- ----- ----- 2A10 537.25 11.939 4A10 332.58 7.391 7A10 220.02 4.889 X 2A20 537.25 5.969 4A20 496.32 5.515 X 7A20 250.72 2.786 X 2S10 537.25 11.939 4S10 383.75 8.528 7S10 235.37 5.230 X 2S20 527.02 5.856 4S20 527.02 5.856 X 7S20 220.02 2.445 X 2R10 511.67 11.37 4R10 378.64 8.414 7R10 204.67 4.548 X 2R20 614.01 6.822 4R20 614.01 6.822 X 7R 163.73 1.819 X 20 Table 3: The Distance between Right Bank and Measuring Lines after Diversin Channel Line A B C D Distance Frm Right Bank (m) 40 80 200 420 Fig. 5: Lcatin f Velcity Measurements A summary f the btained velcity values resulted frm the different simulatins is presented in tables 4 and 5, where the maximum and minimum lngitudinal and transverse velcities are given fr each run tgether with their lcatins with respect t the crss sectin number and line symbl. Lngitudinal Velcity: Table 4 shws that the maximum and minimum lngitudinal velcity (U max, and U min) that ccurred when 0 using a 90 (straight spur) with 20% cntractin rati. These results are in agreement with the results btained by Attia (2006). That assures the fact that using straight spurs with lng lengths, with spacing 4L r less, makes the grup f spurs acting as a firewall against flw which, by its turn, decrease the width f channel and increase the velcity at the middle f the channel and the ppsite bank, t the erected spurs, as well. This 3196
Table 4: Lcatins f the Maximum and Minimum Lngitudinal Velcities Run Name Max. U (m/s) Lcatin Min. U (m/s) Lcatin ------------------------------------- --------------------------------- Line X-Sec Line X-Sec Basic 2.433 C 1-0.122 D 5 2A10 2.394 C 1-0.105 D 5 4A10 1.929 C 1-0.073 D 4 7A10 2.417 C 1-0.112 D 5 2A20 2.446 C 1-0.141 A 6 4A20 2.443 C 1-0.162 A 6 7A20 2.423 C 1-0.168 A 6 2S10 2.391 C 2-0.100 D 4 4S10 2.394 C 2-0.107 A 8 7S10 2.412 C 1-0.109 D 5 2S20 2.479 C 1-0.154 A 9 4S20 2.482 C 1-0.163 A 14 7S20 2.461 C 1-0.175 A 5 2R10 2.398 C 2-0.104 D 6 4R10 2.407 C 1-0.107 D 4,5 7R10 2.421 C 1-0.112 D 5 2R20 2.464 C 1-0.131 A 8 4R20 2.434 C 1-0.152 A 13 7R20 2.433 C 2-0.101 D 5 7S 2.412 C 1-0.109 D 5 10 Table 5: Lcatins f the Maximum and Minimum Transverse Velcities Run Name Max. V (m/s) Lcatin Min. V (m/s) Lcatin ----------------------------------- --------------------------------- Line X-Sec Line X-Sec Basic 0.375 C 1-0.638 C 14 2A10 0.302 C 1-0.605 C 12 4A10 0.237 C 1-0.497 C 13 7A10 0.340 C 1-0.652 C 12 2A20 0.126 C 1-0.631 C 10 4A20 0.145 C 1-0.632 C 12 7A20 0.160 C 1-0.657 C 15 2S10 0.280 C 1-0.598 C 11 4S10 0.299 C 1-0.626 C 12 7S10 0.325 C 1-0.670 C 12 2S20 0.112 C 1-0.632 C 10 4S20 0.087 C 1-0.672 C 11 7S20 0.111 C 1-0.729 C 15 2R10 0.299 C 1-0.592 C 12 4R10 0.317 C 1-0.625 C 13 7R10 0.342 C 1-0.648 C 12 2R20 0.133 C 1-0.625 C 10 4R20 0.183 C 1-0.768 C 11 7R 0.226 C 1-0.811 C 15 20 is used t maintain deep channels that are used in navigatin prcesses. In fact this is ne f the main purpses f using spurs. This agrees with the results cncluded by Ebraheem (2005), as well. The table als illustrates that fr all simulated cases, the maximum lngitudinal velcities are directly prprtinal t the spur length and is lcated at the middle third f the channel alng line C (200m frm right bank),especially, at crss sectins 1 and 2 at the mst cntracted regin (after the flw exits the diversin channel). Frm Table 4 it is nticed that the grup f 4A10 presents the ptimum cnditin fr bank prtectin as it presents the minimum values fr bth maximum and minimum lngitudinal velcities when cmpared t the ther cases. Als, it shuld be mentined that the lngitudinal velcity dminates the scur hles assciated t existence f grins, in ther wrds it can be said that the grup f 4A10 presents minimum bed mrphlgical changes. The investigated spacing agrees with what btained by Msselman (2000). Transverse Velcity: The maximum transverse velcities are slightly affected by changing the spur length, spacing, and rientatin angles, as shwn in Table 5. Hwever fr all simulated cases, the maximum and minimum transverse velcities are lcated at the middle third f the channel. This culd be attributed t the fact that as the flw exits the diversin channel, it impacts the right bank. This causes the flw, in behind, t be diverted away frm that regin. This als explains the negative value f the minimum transverse velcity. It was als 3197
nticed that, fr all the simulated cases, the repelling grup f spurs has higher values f the maximum transverse velcities than that in cases f using straight and attracting grups. This means that larger and deeper scur hles will ccur in frnt f spurs. Mrever, large amunts f dwnstream sediment ccur due t the dead zne f weak flw presented in terms f velcity. In ther wrds, it can be said that scur hles are inversely prprtinal t the rientatin angle measured frm the dwnstream. This agrees with the results btained by Melville (1992). The table als shws that fr all simulated cases, the maximum values f transverse velcity are inversely prprtinal t the spur length and are directly prprtinal t the spacing between spurs. Frm Table 5 it is nticed that the grup f 4A 10 presents the average values fr bth maximum and minimum transverse velcities which is valuable in preventing depsitin f the facing bank f grins erectin. Effects f the Orientatin Angles n Velcities: T test the effect f the rientatin angles n the flw pattern, the relatinships between the velcity and the rientatin angles are pltted fr the basic case and the simulated cases alng the different lines. The cntractin rati was kept cnstant during this investigatin. The rati 0.10 with spacing f 4L was selected. This rati was chsen based n different simulated cases. This ratin is the mst effective influencing parameter. Figure 6 illustrates that at line (A) there is a clear similarity in the trend f bth the lngitudinal and transverse velcities. Hwever, using a grup f spurs at any rientatin angle decreases the lngitudinal and transverse velcities by 50% and 20% respectively, at the different crss sectins when cmpared t basic case. As fr the peak values f the lngitudinal velcities, fr the repelling grup (120 rientatin angle), they were slightly higher at mst f the crss sectins. On the ther hand, the peak values f the transverse velcity, fr the attracting spurs (60 rientatin angle) are lcated just dwnstream the tip f spur. Fig. 6: Lngitudinal and Transverse Velcities at Line (A) fr 0.1 Cntractin Rati and 4L Spacing Fr Different Orientatin Angles 3198
Frm Figure 7, it can be seen that the lngitudinal and transverse velcities, fr line B (80m frm right bank), with attracting spurs shwed lwer values than in case f repelling and straight spurs while bth the repelling and straight spurs have almst equal values. Hwever, using spurs at an angle t the bank imprves the situatin, relative t the basic case, as it decreases the ersive velcity in the vicinity f the right bank. Frm the figure, it can als be cncluded that the lngitudinal velcity is directly prprtinal t the rientatin angle. Hwever, the transverse velcity, using spurs, des nt nticeably change relative t the basic case. Fig. 7: Lngitudinal and Transverse Velcities at Line (B) fr 0.1 Cntractin Rati and 4L Spacing Fr Different Orientatin Angles At the middle f the crss sectin f the channel, alng line (C), the lngitudinal and transverse velcities shw the same trend relative t the basic case using different rientatin angles. Hwever, fr the case f the attracting spurs, lwer values f lngitudinal velcities, relative t the basic case, were bserved. On the cntrary, the repelling and straight spurs gave the greater values relative t the basic case. This means that repelling and straight spurs maintain deep channel fr navigatinal purpses mre than the attracting spurs. Mrever it was nticed that the tested rientatin angles had the same trend and value f the transverse velcity, relative t the basic case. Als, it is nticed that the grup f 4A 10 presents the best slutin t disperse the velcity away frm the attacked bank. At line (D), alng the ppsite bank, the lngitudinal and transverse velcities fr the tested cases shw the same trend relative t the basic case. It shuld als be mentined that the tested cases have higher values relative t the basic case and are directly prprtinal t the crss sectin frm the pint f view f the lngitudinal velcity. On the cntrary, the transverse velcities, fr all the tested cases, are lwer relative t the basic case. They are als inversely prprtinal t the crss sectin. In additin t that, the lngitudinal velcity, in case f the attracting spurs, has a higher value than in case f the tested repelling r straight spurs. The attracting grup presented in 4A 10 prves effective perfrmance in preventing the depsitin at the ppsite bank. 3199
Fig. 8: Lngitudinal and Transverse Velcities at Line (C) fr 0.1 Cntractin Rati and 4L Spacing Fr Different Orientatin Angles Fig. 9: Lngitudinal and Transverse Velcities at Line (D) fr 0.1 Cntractin Rati and 4L Spacing Fr Different Orientatin Angles 3200
Tables 6 and 7 summarize the average lngitudinal and transverse velcities, respectively, fr a grup f spurs with 10% cntractin rati and 4L spacing at different rientatin angles and velcity lines. Als, the percentage f reductin r increase relative t the basic case is given in the same table. It shuld be nted that the negative sign refers t the reductin in value. Table 6: Average Lngitudinal Velcities at Different Orientatin Angles Angle Line Average Lngitudinal Velcities (m/s) % Basic Case --------------------------------------------------------------------------- ------------------------------------------------------------ Basic 60 90 120 60 90 120 A 0.956 0.297 0.253 0.391-68.933-73.536-59.100 B 1.492 1.005 1.21 1.261-32.641-18.901-15.483 C 1.459 1.321 1.712 1.669-9.459 17.341 14.393 D -0.053 0.03 0.014-0.006 156.604 126.415 88.679 Table 7: Average Transverse Velcities at Different Orientatin Angles Angle Line Average Lngitudinal Velcities (m/s) % Basic Case --------------------------------------------------------------------------- ------------------------------------------------------------ Basic 60 90 120 60 90 120 A -0.19-0.062-0.051-0.082-67.368-73.158-56.842 B -0.26-0.204-0.249-0.251-21.538-4.231-3.462 C -0.306-0.311-0.391-0.373 1.634 27.778 21.895 D -0.002-0.032-0.031-0.025 1500 1450 1150 Frm the abve tables, it can be cncluded that, at mst f the velcity lines, bth repelling and straight spurs have apprximately similar values f transverse velcity. Line (C) represents the impact f spur implementatin n the velcity at the middle f the channel. The attracting spurs (60 ) reduced the average lngitudinal velcity, while the straight and repelling spurs prduced greater values relative t the basic case. Therefre, implementing repelling spurs will be useless as it culdn't create a slack flw upstream, while the attracting grup f 4A10 acts efficiently at the attacked bank. It maintains the depth at the middle f the channel and prevents the depsitin at the left bank. Als, it shuld be mentined that using the grup f 4A 10 decreases the velcity in the vicinity f the 450m erded bank by apprximately mre than 65% as an average value. As fr straight spurs, they can be used fr the purpses f bank prtectin and t increase the depth at the middle f channel fr navigatinal aims. Cst Evaluatin Test: The ttal number f grins in each simulatin case plays an imprtant rle in chsing the ptimum slutin fr minimizing bank ersin prblem in the diversin channel. The number shuld prvide enhancement in bank prtectin, at the same time the cnstructin cst shuld be reasnable taking int accunt a fewer numbers f grins never refers t lwer cst. The ttal number f grins is a functin f grin length and spacing such t cver the 450m frm the bank under study. In ther wrds, the ttal number f grins is inversely prprtinal t grin length and spacing. As the angle f rientatin desn't impact n the number f grins; in Figure 10, the symbls A, S, and R are replaced by symbl (G). The present cst evaluatin test fr the simulated cases is a rugh estimatin fr cst as it's presented as a functin f ttal length fr different runs. The ttal length is presented by multiply the grin length by number f grins fr each case. Fig. 10: Ttal Length f Grins fr Different Simulatin Cases 3201
Cmbining Table 1 and Figure 10 clearly indicates that, the maximum length was fund fr the grup f 20% cntractin rati and 2L spacing; hwever the number f grins fr that grup is 3 which isn't the maximum ne that indicates the higher cst. Mrever, using a grup f 10% cntractin rati length presents mre ecnmic slutin when cmpared t 20% cntractin rati length. After discussing the technical parameters f wrking length and cntinuity clearly was that, fr different rientatin angles, nly the grups f 10% length with 2 and 4L spacing was technically succeeded in bank prtectin. Hwever, the grup f 4L spacing had the mst ecnmical cst. Cnclusin and Recmmendatins: This research investigated the effect f spur installatin n different parameters. Fr the wrking length it was fund that using repelling spurs (120 with 0.20 cntractin rati with spacing less than 4L) prduced the lngest wrking length. Hwever t keep the wrking length cntinuus it is preferred t use spurs with length less than 10% f the channel width with spacing less than 4L. It was fund that the maximum velcity fr the tested cases is similar t the basic case velcity. On the ther hand, using attracting spurs (0.10 cntractin rati and 60 rientatin angle with spacing f 4L) prved t be the best case fr bank prtectin and sedimentatin prcesses. All maximum lngitudinal velcities are lcated at the middle third f the channel and all minimum lngitudinal velcities are lcated near the channel sides. The maximum and minimum transverse velcities are lcated at the middle third f the channel; als the maximum values f transverse velcities are inversely prprtinal t spur length and are directly prprtinal t the spacing between the spurs. Fr fixed spur length and spacing, it was fund that using a grup f spurs at any rientatin angle decreases the velcity at the different crss sectins in the vicinity f the bank by 50% and 20%, fr the lngitudinal and transverse velcities respectively. At the middle f channel it was fund that nly the attracting spurs shw lwer values than the basic case fr lngitudinal velcities, while at the ppsite bank f erectin it was fund that the tested cases have higher values than the basic case. This means that using attracting spurs is prtecting the bank ptimally due t the impact f diversin channel. Hwever bth repelling and straight spurs maintain deep channel. Hwever, testing the ecnmic cst prved that this case is nt the least cst frm the ecnmical pint f view. The study recmmended that similar study shuld be cnducted using submerged spurs rather than emerged spurs. A checklist shuld be created after simulating mre cases t define the suitability f each type accrding t the tackled prblems. A cmplete ecnmical study shuld be cnducted and evaluated relating t the ptimum technical evaluatins. REFERENCES Attia, K.M. and G. Elsaid, 2006. The Hydraulic Perfrmance f Oriented Spur Dike Implementatin in Open Channel Paper presented t Tenth Internatinal Water Technlgy Cnference, Egypt. Ebraheem, M.M.M., 2005. Hydrdynamic Behavir f Bank Prtectin Structures (Grins) Thesis Submitted t Faculty f Engineering, Banha University fr partial Fulfillment f the Requirements fr Master Degree f Science in Civil Engineering (Irrigatin & Hydraulics), Egypt, Nvember. Klingeman, P.C., S.M. Kehe and Y.A. Owusu, 1984. Stream Bank Ersin Prtectin and Channel Scur Manipulatin Using Rck Fill Dikes and Gabins, (N. WRRI-98), Oregn state University, Water Resurces Research Institute, Crvallis, Oregn, USA. Mlinas, A. and Y.I. Hafez, 2000. Finite Element Surface Mdel fr Flw arund Vertical Wall Abutments, Jurnal f Fluid and Structures, 14: 711-733. Msselman, E., 2000. Technical Memrandum n Gryne Length and Spacing, Delft Hydraulics Lab. Cmmunicatin, Delft, The Netherlands. Melville, B.W., 1992. Lcal Scur at Bridge Abutment, Jurnal f Hydraulic Engineering, 118(4): 615-631. 3202