Technical Report CHL-99-17 July 1999 US Army Corps of Engineers Waterways Experiment Station Damage Progression on Rubble-Mound Breakwaters by Jeffrey A. Melby Approved For Public Release; Distribution Is Unlimited TA om wart CULL AA- (1% Prepared for Headquarters, U.S. Army Corps of Engineers The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. The findings of this report are not to be construed as an official Department of the Army position, unless so desig- nated by other authorized documents. & PRINTED ON RECYCLED PAPER Technical Report CHL-99-17 July 1999 Damage Progession on Rubble-Mound Breakwaters by Jeffrey A. Melby U.S. Army Corps of Engineers Waterways Experiment Station 3909 Halls Ferry Road Vicksburg, MS 39180-6199 Final report Approved for public release; distribution is unlimited Hmmm TO Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 Under Civil Works Research Work Unit 32792 rats US Army Corps of Engineers Waterways Experiment Station FOR INFORMATION CONTACT: PUBLIC AFFAIRS OFFICE U.S. ARMY ENGINEER WATERWAYS EXPERIMENT STATION 3909 HALLS FERRY ROAD VICKSBURG, MISSISSIPPI 39180-6199 PHONE: (601) 634-2502 AREA OF RESERVATION = 2.7 sq km Waterways Experiment Station Cataloging-in-Publication Data Melby, Jeffrey A. Damage progression on rubble-mound breakwaters / by Jeffrey A. Melby ; prepared for U.S. Army Corps of Engineers. 216 p. : ill. ; 28 cm. -- (Technical report ; CHL-99-17) Includes bibliographic references. 1. Rubble-mound breakwaters -- Stability -- Testing. 2. Breakwaters -- Stability -- Testing. 3. Coastal engineering. 4. Flumes -- Testing. 5. Hydrodynamics. |. United States. Army. Corps of Engineers. II. U.S. Army Engineer Waterways Experiment Station. Ill. Coastal and Hydraulics Laboratory (U.S. Army Engineer Waterways Experiment Station) IV. Title. V. Series: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CHL-99-17. TA7 W34 no.CHL-99-17 TABLE OF CONTENTS IPTC LAC Se te eran een eee ene ier ourciesTanciy cy crate menay Ste hulls ae laytevts cea ispamene a UeeaeA a XV Chapter TS SINTRODUGCRION aks ac cts hee ee ane eC ec eae 1 2 INCIPIENT STABILITY OF BREAKWATER ARMOR UNITS ....... 6 Do) SArmorstapllaty EQuations eye ciysisrss ce aie ee eae eee eee naneer ae 6 De Armornincipieny Motion Studies aes oe se eee ee eee eee 10 DSREXMerimentalt SCLUD = «sects ) 8a) sre site se Gare ceases Sete aoe 12 ZA sincipientiMoton| Observations) s55 24. eee ee 17 2 OMexpernmentaluMeasurementSmn a6 ee ee eee eee ieee 18 2 oeincipientyMotion bredictionees se ono eel oe ee 22: 2.7 Conclusions from Incipient Motion Study .......................- a2 3 HISTORICAL DAMAGE MEASUREMENT AND DESCRIPTION .. 33 3.1 Damage Modeling Standards ........... Ben cadt Oe Re a cece 33 32 sDamage Measurement MiethoOdSmen yeti eer eee rrr 34 Sal mErodedivolime methodue saree aan ee ee eee 34 3922" Stone count method yen cs ase ee ain secretions ol mat nreney ae 40 3.2.3 Recent damage measurement methods ....................- 40 358 Damage Measurement ExXpeniments eee area ee rae 41 34a Damage brocressioneredic ony sna ae enee eee oe cee 44 BES) WVartabilityintStabilityaResnlisie ne see eee ee oer 50 DETERIORATION EXPERIMENT .................-.---222-0055 53 ASIMOV CLV Wire ehicid Si ators eis 28 She he BIS Career pee MON ATOM CREE NES chet een aac ea 53 49 JExperimentall Setups. ac oc o seats ecto elo ee tay vate my nies) ee eg emt 54 4.2.1 Flume and structure ..................... desi 54 42-2 Experimentalitesticonditions» sae eee ee eee 56 4.2.3 Armor layer andiunderlayemna. . seen ee se eee 56 42-4) Model-Prototype similitude = --e 545 oee eo 60 4.3 Wave Generation and Measurement in Initial Experiment ............. 62 4.3.) Wave generation 2)... 2.245... 3. eee els s. 5s oe ee eee 62 4.3.2 Wave measurement). 22.2 coals, - Oe Eee 64 4:4 Effect of Overtopping on Stability ----..25..---5.5.-59- 5 see 74 4.5 Armor Profiler and Profile Measuring Technique ................... 74 DAMAGE MEASUREMENTS .............-..----- 02-22 esse eee 81 $18 OVErviewW 52. AB Re ees ee in gy AE ete cis bs Slain cnet ee 81 5-2) Damage and Eroded Profile Parameters ..- 2.2 33-7) eee 83 5.3 Probability Density Functions of Damage, Eroded Depth, and Cover Depths: ssi ke fs Seley. ete BA te islslotsiel 9) Se Seen 85 5/4hemporal Damace Developments. 5-60) 0 ee eee 90 5:5) Characteristics of Profile Erosion (442) 2.14.5 - soo eee 100 DAMAGE AND ERODED PROFILE PREDICTION .............. 110 6:1 Damage Variability... 22 sc3 552). 230s oe Meee oe eee 110 6:2, Eroded' Profile Prediction) 3.05 ....5 oleic ieveueysiae ble re 111 6:3) Temporal Damage Development = -).5.5-)5-2 eee 117 EFFECT OF WAVE PERIOD AND ARMOR GRADATION ON DAMAGE PROGRESSION | 2 o:.06:5 5 :sje sie ee eietecins © 2 oe 127 7.1 Experimental Setup and Test Conditions .....................---- 127 7.2 Probability Density Functions of Damage, Eroded Depth, and Cover Depth ac scitratee sao etn Gaciaoues oe a or eee 131 7.3\ Damage) Variability 3 ee) ee oo Sone ote eee 133 7-4. Eroded Profile Predictionvan = -5- ee eee ee ee eee 134 eS hemporal/ Damage Developments e ee ee eee eee eee 139 SUMMARY AND CONCLUSIONS .................--------+--- 144 Appendix A B SF 298 SUMMARY OF WAVE MEASUREMENTS SUMMARY OF DAMAGE AND PROFILE MEASUREMENTS REFERENCES vi Hell 2.1 DDD) De 2.4 25 2.6 Oeil 2.8 DS) 2.10 Salk LIST OF FIGURES Breakwater failure modes |. 2.0.0 ec ch cgeisiend occ de ws ik os See 2 Flume plan (top) and profile (bottom) views for incipient motion EXPETIMENE ooo. oe nese eta ee och ane ic ioe a gees dis, sol ose 13 Definition sketch for typical structure profile ......................-...- 14 Velocity time series for one wave period with H, = 12 cm, T= 1 s, d,=24 cm and d, = 8.8 cm measured 1 cm outside the armor layer .................. 19 Velocity vector for one wave period for armor lifting measured 1 cm outside the armor layer with H, = 8.4 cm, T=2s,d,=24cm, andd,=17cm. ....... 20 Vertical velocity time series outside (top) and inside (bottom) armor layer with H, = 12 cm, T= 1s, d,=24 cm, and d, = 8.8 cm for the outer measurement and d, = 13 cm for the inner measurement .................. 20 Measurement locations for vertical velocities shown in Figure 2.5 .......... 21 Maximum vertical velocity versus the square root of wave steepness for wave periods T= 1 and 2 s and relative depths rd = 0.36, 0.5, and 0.7. ........... DD) Vertical variation of vertical velocity under a steep wave front across the armor layer as a function of wave steepness ..............-.--.-.------- Di Photographs of sphere motion during a typical incipient motion experiment HITE? go gRoadopcesscoosccomn sco RsoasoeocEasacasoonES CCC EoSS 30 Incipient motion criterion (Equation 2.14 with v. = 61.8 cm/s) versus wave OK ioj 0] 8 eri er Se RCRA RIS GMMR VARH AIAN ele orSicro'> 6b 0 oo oc Sill Sketch of breakwater profile with definition of eroded area and depth of (10)( 3 ee eee Aer ay nee eae ee MRR A an ee cee ne nS 6.0.0 0 6 34 Damage, characterized as eroded volume, as a function of monochromatic 4.4 4.5 4.6 4.7 4.8 4.9 5.1 3 38) 5.4 3-5 5.6 Sei 5.8 wave height for angular stone (SPM 1984) ............................. 46 Hudson stability coefficient versus relative depth for angular armor stone exposed to irregular waves (Carver and Wright 1991) .................... 52 lume pronletomdamasciexpenimentsiy- eerer a eeere aa ee ee 54 Model structure cross section for damage experiments ................... 54 Photograph of model structures before testing .......................... SS) Armor and underlayer stone mass distributions for initial experiment ........ 58 Flume profile near structure with nearshore wave gage layout ........... 65 Wave height variation throughout Waves 1, 2, and 3 at 11.9 cm toe depth .... 71 Wave height variation throughout Waves 4, 5, and 6 at 15.8 cm toe depth .... 71 Plan (top) and profile (bottom) views of breakwater profiler ............. 75 Photosraphiofbreakwaterproiilenseee eee Oe eee ee 76 Sketch of breakwater profile with definition of damage parameters ....... 84 Probably density function for normalized damage S* for SeriesvA AB Bandi Sart 28) Se es UA Ege Re RE ce bea 88 Probability density function for normalized eroded depth £* for SerlessARCB rami Gees n Mc eh es aera Sa RO a TR po ae 89 Probability density function for normalized cover depth C* for SERIES AL VB etanndls Coe Ate eo Bont (ey METOE II A PRIE RUE ee W AR ON Ie oa ce a ee at 89 Photographs of undamaged structures prior to Series A’.............-..-- 91 Profiles at beginning of Series A’, damage level of S= 0 ................ 92 Profiles midway through Series A’, damage level of S=6.5 ............. 93 Profiles following completion of Series 4’, damage level of S= 12.8 ...... 94 Vil Vili Ss) 5.10 Spllt 5212 Sal3 5.14 SpLlS) 5.16 Soll 5.18 Sell 5.20 Alt Sf S23) 5.24 Photographs of structures following completion of Series 4’, damage level Of S128 on, PERG I ea re 95 Number of waves versus mean damage + one standard deviation for Series Ae: 5 LSS FS i Pa Toe, oven A Nena ie ote sae 96 Number of waves versus mean damage + one standard deviation for SEGlES Bites 25 Me ale Soke eles See eR ER 99 Number of waves versus mean damage + one standard deviation for Series es acc hhh SEN A RI ae SONS 2G Ee a 99 Number of waves versus mean maximum eroded depth + one standard deviation for:Series 40.5. o ks 8 oe le au ieee ye eee 101 Number of waves versus mean minimum cover depth + one standard deviation:for Semes‘A” 62. isos ae ee SE, ee 102 Number of waves versus mean maximum eroded length for Series A’....... 102 Mean damage versus mean maximum eroded depth and mean minimum cover depth for Series A”. 55 5 oe ao Ss te see oes eee 103 Mean damage versus mean maximum eroded length for Series A’.......... 104 Number of waves versus mean maximum eroded depth + one standard deviation for'Senes BY. .8.s So ee eee ee OE, 6 ee 105 Number of waves versus mean maximum eroded depth + one standard deviation for Series! Ce a eee ES A oe 105 Number of waves versus mean minimum cover depth + one standard déviation for Series Bnet Me Ne en Pe er 106 Number of waves versus mean minimum cover depth + one standard deviation'for'Seres’C? Tyas ie Se eee ee. ee er 106 Number of waves versus mean maximum eroded length for Series B’....... 107 Number of waves versus mean maximum eroded length for Series C’ ...... 107 Mean damage versus mean maximum eroded depth and mean minimum cover depth for’ Series By acs ee as ae eiluek avery nea 108 325 5.26 Sai 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 Well UZ ES 7.4 V2 Mean damage versus mean maximum eroded depth and mean minimum COVERdEepthtOR SCENES C oo) Ope. Narpac Se cook Meee the elec ele esas adress 108 Mean damage versus mean maximum eroded length for Series B’.......... 109 Mean damage versus mean maximum eroded length for Series C’ ......... 109 Prediction of damage variability, characterized by the standard deviation, as a function of mean damage for Series A’, B’, andC’................-.. 111 Prediction of mean maximum eroded depth as a function of mean damage LOR SCTLCS VA Dp AN Gig eco eee) rc At ee meer SN ae Celia ven al et tes ane 112 Prediction of standard deviation of maximum eroded depth as a function of meandamage tole Series Avy and) Guess ea eee een 112 Prediction of mean of eroded length as a function of mean damage for SeriesrAV SB andi Gee ficensywy pevyahg hay day Sasa hears clas Ro ag 114 Prediction of mean minimum cover depth as a function of mean damage for SeriesPAreB Mam dy ais oe Werete ks acanah ne tee meas eects ST en eo eae 115 Prediction of standard deviation of minimum cover depth as a function of mean damage tomSeries Avy by1and Gai sears Sa a eer eal 116 Damage prediction relations compared to data for Series A’ .............. 125 Damage prediction relations compared to data for Series B’ .............. 126 Damage prediction relations compared to data for Series C’ .............. 126 Stone mass distributions for nprap and underlayer...................... 130 Probability density function for normalized damage S* for Series Dandi G Wa Sere Sapp tears opal 1 cute wees eee ean 132 Probability density function for normalized eroded depth E* for Senes: DE FS andG ©. sayreqe Ae AI Bee Cte oe ane nese 132 Probability density function for normalized cover depth C* for Series DESH wands G owt eget, Sion cg SR AY Aah, eon ere Satis eee 133 Prediction of damage variability, characterized by the standard deviation, as a function of mean damage for Series B’, D’, E’", F’,andG’............. 134 7.6 Wel! 7.8 US TAY 7.16 Volt Tf 7.18 A.l A.2 Prediction of mean maximum eroded depth as a function of mean damage for Series BY. DEF) andiG 4.55 tee Oe ee 135 Prediction of standard deviation of maximum eroded depth as a function ofmeantdamace for Seres/s 49 Ee) hin and Gene ee 136 Prediction of mean maximum eroded length as a function of mean damage for:Series BD! Sik Cand Giga Fe Ae tae a ots tots 136 Prediction of mean minimum cover depth as a function of mean damage for Series BYDiE Ei Fang Gn s Ves ORR A ee nets cas ah 138 Prediction of standard deviation of minimum cover depth as a function of mean\damace for Series!h aD Er @andiGae es -eee ee e 138 Damage prediction relations compared to data for Series D’ .............. 140 Damage prediction relations compared to data for Series E’ .............. 140 Damage prediction relations compared to data for Series F’ .............. 141 Damage prediction relations compared to data for Series G’ ...........-.. 141 Damage prediction relations compared to data for Series D’ including damaveinitiationadjustment) ean eee ee eee eee Eee 142 Damage prediction relations compared to data for Series E’ including damavelinitiation\adjustment a.) s+ ee ee oe oe oe oe oe 142 Damage prediction relations compared to data for Series F’ including damage initration’adjustment) pee aaa eee eee eee 143 Damage prediction relations compared to data for Series G’ including damage initiationtagjustmenthe year me nae eo eee ee eee 143 Wave generator command signals for six wave cases. The original signal was 900 sec but 10 sec was clipped from either end for analysis and this figure Shows the)shorteneditime seriesue nse ae ee een oes 158 Spectra of wave generator command signals for Waves 1, 2, and 3 for PL9:cm toeideptht net rcy vee eees cee eee eet anna bk niece ep Vetere 154 A.3 A.4 A.5 A.6 A.7 A.8 A.9 A.10 A.l1 A.12 TAS A.14 A.15 A.16 A.17 A.18 A.19 A.20 Spectra of wave generator command signals for Waves 4, 5, and 6 for HSw/temaitOerdep thst me sine acs notes iN ai Syren ian AE us ey Va ens a eT a 154 Wave | time series from wave gages. The original signal was 900 sec but 10 s was clipped from either end for analysis and this figure shows the ShOrtenedstene Serres ee y..5 ae see ecteek oe ae a. cree yee ope Bees eo 155 Wave 2 time series from wave gages. This figure shows the shortened {Me SEKeSas Ini hiOUTerAUA ae Sse Ate ARN Mirae tea yma os 156 Wave 3 time series from wave gages. This figure shows the shortened HIME! SETIes tas IM UN TOUTS AVA are eet trey ection ee eras OR a MeL al Mesenay es meters 157 Wave 4 time series from wave gages. This figure shows the shortened time Senies! aspiMemIS ure AlAs a 2 A aerweh waren reves (etna nin ease LAP 158 Wave 5 time series from wave gages. This figure shows the shortened TUMe)SEIES ASIN RIO UNE ALA. 2 ecg ee i oe een rel eau nie Men mre meng an 159 Wave 6 time series from wave gages. This figure shows the shortened time! seniesiasiiniFrguine; Acd say. Peat yest aie Se pnd, aR aeS ooo orale ae cee 160 Wave | incident and reflected spectra from wave gages ................. 161 Wave 2 incident and reflected spectra from wave gages ................. 162 Wave 3 incident and reflected spectra from wave gages ................. 163 Wave 4 incident and reflected spectra from wave gages ................. 164 Wave 5 incident and reflected spectra from wave gages ................. 165 Wave 6 incident and reflected spectra from wave gages ... PON Nas get erew 166 Wave 7 incident and reflected spectra from wave gages ................. 167 Wave 8 incident and reflected spectra from wave gages ................. 168 Wave 9 incident and reflected spectra from wave gages ................. 169 Wave 10 incident and reflected spectra from wave gages ................ 170 Wave 11 incident and reflected spectra from wave gages ................ 171 xi xii A.21 A.22 A.23 A.24 A.25 A.26 A.27 A.28 A.29 A.30 A.31 A.32 A.33 A.34 A.35 Wave 12 incident and reflected spectra from wave gages ................ 2 Wave 13 incident and reflected spectra from wave gages ................ 173 Wave 14 incident and reflected spectra from wave gages ................ 174 Wave 15 incident and reflected spectra from wave gages ................ VAS Wave 16 incident and reflected spectra from wave gages ................ 176 Wave 17 incident and reflected spectra from wave gages ................- 177 Wave 18 incident and reflected spectra frOMMWAVe Sages eee 178 Wave 19 incident and reflected spectra from wave gages ................ 179 Wave 20 incident and reflected spectra from wave gages ...............- 180 Wave 21 incident and reflected spectra from wave gages ................ 181 Wave 22 incident and reflected spectra from wave gages ...............- 182 Wave 23 incident and reflected spectra from wave gages ................ 183 Wave 24 incident and reflected spectra from wave gages ................ 184 Wave 25 incident and reflected spectra from wave gages ...............- 185 Wave 26 incident and reflected spectra from wave gages ................ 186 Dell DD 23) 2.4 3.1 4.1 4.2 4.3 4.4 Soll 6.1 del V2 B.1 B.2 B.3 LIST OF TABLES Experimental Plans for Incipient Motion Experiments ................... 14 Ranges of Measured Physical Quantities and Common Dimensionless RatametersfOrmlelans Ss and Asie gs styrene Sy atone ei i eee 15 Summary of Convection Measurement Experiment Results with cot 6=2, Dea 4 6icmimand' a) = 24 vemiwye Wastes disci Ae eae hr 26 Summary of Incipient Motion Experimental Results .................... 31 Jackson (1968) Breakwater Damage from Table 7.9 of SPM (1984) ........ 45 Experimental Conditions for Initial Damage Experiment ................. Sy) Wave Generation in Initial Damage Experiment ........................ 63 Nearshore Wave Statistics for Incident Spectra and Related Parameters with Structure. inyPlaces 4. Strat. Maer oes