THE REFLECTING PCMSR OF MARITIME WORKS EXPOSED 



rO ACTION OF THE WAVES 



hj 



M. 1-fi.che 



Tlnis paper in the jf^-snch language vias published in the I-ky- 

 Jaue 1951 Annals of the Highway DepartirBnt^ National Press (France), 

 Ari English translation is on file at the Beach Erosion Board 

 Library. An abstract of this paper xd.th the major findings of the 

 author is presented herewith, A translation from the Spaiiish of 

 a paper by Ramon Irribarren Cavanilles and Casto Nogales Y Olano 

 entitled "LiMting Batter (Slope ''! Bet'ween the BreaMng and Re- 

 flection of Waves" appeared in Tolume 5^ issue n"amber 1 of the 

 3u.lletin dated 1 April l?!;^!. In that paper a forraula for the 

 linating slope of a structuj"e e^oosed to wave action was evolved 

 in terras of the wave chaj-acteristics, wtere slopes flatter than 

 the limiting slope tend to give total breaking and steeper, .slopes 

 tend to give total reflection of the incident wave. This paper 

 Dj i-fr. ffi-che is an e:cfcension to the work by Ir^'ibarren and Nogales 

 in tha.t 1%", 1'S.che evolves relationships, useful in design^ for 

 determining the 3j1plitu.de of the reflected wave for partictilar 

 incident waves and t;'/pes and slopes of the intercepting structures. 



In the paper the author discusses the general considerations involved 

 in deterrimiing the ability of a raaritiriie structure to reflect sea waves. 

 His findings aX'e based on the conditions that the wave does not break before 

 reaching the structure or overtop the structure after reaching itj the waves 

 attack the structui'-e frontal-ly or are unaffected by refraction or diffraction, 

 the structure is not convex or concave seaward, and that the structure has 

 a continuous slope, or a forFi capable of being e^ipressed as an equivalent 

 slopes 



The maXLiTiuTii value of the steepness ratio j rua^c in deep water of a 

 wave capable of being, theoretically, tota3.1y reelected by a -structure in- 

 clined at angle a mjth the horizontal is given by the formula; 



Y/~2a sin^a /^ \ 



or If G < 1$'' (tan a about 0.27 ;, the formula approicimates; 



'Y Ms-X ~ ~y-~^ (where i ^ tan a ) (1 ' ) 



Figure 1 shoxfs this relations Mp graphically. 



The author coripcres results froni the above formula 1 'tslth test data 

 obtained by Irribarren and Nogales to verifj'- their oxm forimila (i = l^/T v^h'^g ) 

 and tMs conparison is shoi-m in Table 1, Conparison of coliutms h sxid 7 shows 

 reriiar'kably good agreement. 



