would be raised to 29 and 23, respectively, for the artificial 

 blocks and natural stones. 



More, really, than the weight of these blocks or stones, this 

 increase would affect the batters of the projects, flattening them 

 a little, and it should be remembered that th e sa id reduced safety 

 factor of 1.5 mould only suppose a margin of 3/1 .5 = 1.15 in the 

 wave height or in the size of stones. 



In any event, and with respect for strict economy, one can 

 neglect said reduced safety factor, continuing to use the primitive 

 coefficients of 15 and 19 on large dikes where the stones are 

 carefully placed to a considerable depth, provided that the in- 

 crease of wave height produced by the work itself is always 

 calculated following the indicated procedure . 



On the other hand, and to simplify the calculations on the 

 smaller dikes, said factor of 1.5 can be adopted, that is, 

 coefficients N equal to 23 and 29, en the dikes whose stones are 

 carefully" placed to a lesser depth, and by virtue of this pre- 

 caution being able to take the incident wave height rather than 

 the height of wave that breaks over the dike, as already indicated 

 textually in 1938 . 



The theoretical relative breaking depths, deduced from the 

 cited table and the curve VK-/a 0/ & f Figure 22 of the report, 

 being H cz. 0*03, to which a wave height amplification 



L o 

 factor of 1.3 applies, it will be possible to calculate a rock 



fill dike on the basis of the incident wave height and adopting 



the cited coefficients 29 or 23 that include the safety factor 



1.5. whenever the relative depth of its toe is less than H = 0.06, 



Lo 



corresponding to the amplification factor of the cited curve 

 -^ = 1.13, or whenever the depth of careful placing of the stone 



^5 



of the dike is less than H x L = 0.06 x 250 - 15 meters on our 



L~o ~ 

 Gantabrian coasts, or H x L = 0.06 x 150 = 9 meters on the 



Mediterranean coa sts . 



As was made a matter of record in the XVII International 

 Congress of Navigation convened in Lisbon, it is also highly 

 satisfactory that the formula deduced in the American report of 

 Epstein and Tyrrel for reflecting rock fill dikes, starting 

 from our expression for pressures of reflection P = OT *, Is 



-* See the cited report Calculation of Vertical Dikes (Calculo de 

 diques verticales) „ 



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