DESIGN OF RIPRAP REVETMENTS 

 FOR PROTECTION AGAINST WAVE ATTACK 



by 



John P. Ahrens 



I. INTRODUCTION 



Quarrystone is the most commonly used material for protecting earth embank- 

 ments from wave attack because, where high-quality stone is available, it pro- 

 vides a stable and unusually durable revetment armor material at relatively low 

 cost. This report provides information and specific guidance on the design of 

 stone riprap revetments, including several examples to illustrate the concepts 

 presented. It supplements Sections 7.21 and 7.37 of the Shore Protection Manual 

 (SPM) (U.S. Army, Corps of Engineers, Coastal Engineering Research Center, 

 1977). 



II. RIPRAP DESIGN CONSIDERATIONS 



The discussion in this section draws heavily on laboratory studies of rip- 

 rap stability. Currently, there is little well-documented information avail- 

 able on the field performance of riprap. In the design of a riprap revetment, 

 a careful evaluation of the performance of riprap or other revetments near the 

 design site or at similar sites is an important adjunct to the guidance given 

 in this report. Information on the design of armor and filter layers, zero- 

 damage and reserve stabilities of the armor layer, selection of overlay armor 

 to upgrade existing revetments, and wave runup is given in this section. Two 

 design aspects which are particularly difficult to study in the laboratory in- 

 clude the toe design of a riprap revetment and tying the ends of the revetment 

 into a nonreveted embankment. Consequently, these aspects are not discussed 

 in this report since little information is available on them. 



A definition sketch for some terms used in this section is shown in Figure 



\_j^-Continuation of Structure Slope 



Filter Loyer, 



-Armor Loyer of Riprop 



r 



J 



Design Water Level- 



\^ZZZ?Zz&yJl!l shore Slope 



Angle Structure Face Makes 

 with Horizontol 



Figure 1. Definition sketch. 



'MVMW////, 



