Variations in groin design

By D. W. Bergl and G. M. Watts2

ABSTRACT

A brief review of groin types and their respective functional designs is presented. Illustrative examples of conventional groins and some of the variations in the basic groin types, which have been constructed in the United States, are shown for comparative purposes.

INTRODUCTION

Of the numerous types of structures developed for shore protection purposes, the groin is probably the most widely utilized although its func-tional behavior is perhaps the least understood. Examples may be found where a single groin or groin system achieved its intended purpose, while similar structures in different locations have provided little or no pro-tection. In addition, there are a seemingly endless number of variations in groin designs, some of which have been purported to be the ultimate an-swer to shore erosion.

The basic cause for the variety in groin designs and the diversity of opinions on the merits of each design, is the lack of established theoretical

IHydraulic Engineer, Engineering Development Division, U. S. Army Coastal Engineering Research Center, Washington, D. C.

2Asst• Chief, Engineering Development Division, U. S. Army Coastal Engineering Research Center, Washington, D. C.

comes an expensive experimental exercise.

BASIC GROIN TYPES

The primary purpose of groins is to provide, build, or \~iden a pro-tective beach by trapping the available littoral drift or to retard the erosion of an existing beach. The structural features of groins, by which these purposes are accomplished, divide groins into two general categories, permeable and impermeable.

Impermeable groins are constructed of various materials, and are de-signed to present a complete barrier to the passage of any available lit-toral drift. Thus, the littoral drift is forced around the seaward end of the groin or, if sufficient beach material has been trapped by the groin, to pass over its top. Permeable groins are designed so that an appreciable quantity of the available littoral drift will pass directly through its structural components.

Within these two general classifications of groins there are further defining functional characteristics. These characteristics are groin height, length, and when more than one groin is utilized in a system, groin spacing. Additional factors such as materials, design, construction techniques and procedures, and necessary periodic maintenance also affect the functional behavior of groins but are generally more closely related to engineering economics.

The height of a groin, especially an impermeable type, determines the extent to which the groin will impound littoral drift. Basically, a high groin acts as a complete littoral ba~rier, and a low groin will i~pound only a portion of the drift, thereafter allowing the passage of material over the top of the groin.

The length of a groin determines the extent to which foreshore and beach profile will adjust in the vicinity of the structure.

The spacing of groins in a system is a significant factor in the ex-pected alignment of a beach. Spacing is dependent on the groin length and volume of available littoral drift.

The preceding parameters apply equally as \~ell to permeable groins. However, since a portion of the drift is allowed to pass through the groin at all elevations and through its entire length, the resulting changes in the beach and nearshore topography are less than those for an impermeable

The main purpose of this paper is to show the variations in groin designs and to illustrate typical structures that have been built in the United States. Undoubtedly there are many varieties other than those which are shown.

It should be pointed out that no analysis is presented here, relative to the effectiveness of the groins.

3Technical Report No.4, "Shore Protection, Planning and Design." Beach Erosion Board, U. S. Army Corps of Engineers, 1957, Rev. 1961.

Figure 1. Impermeable, monolithic concrete groin; Point Mugu, California

Figure 2. Impermeable, precast concrete block groins; Presque Isle Peninsula, Pennsylvania

Figure 3. Impermeable, precast concrete block groin; Waikiki Beach, Hawaii

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Figure 4. Typical section of an impermeable, precast concrete block groin designed by Har-rison Weber

Figure 5. Impermeable, precast concrete block groin, Harrison Weber design; East Hampton, Long Island, New York

Figure 6. Impermeable, precast concrete groin, utilizing pre-stressed concrete panels; Maderia Beach, Fla.

Figure 7. Impermeable, precast concrete sand traps/groins; Presque Isle Peninsula, Pennsylvania

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Figure 8. Typical section of an impermeable, precast coP

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Figure 9. Impermeable, precast concrete block groin, C. T. Leeds

Barbara, California

Figure 10. Impermeable, precast, prestressed concrete pile groin; Seal Beach, California

Figure 11. Impermeable, concrete groin,

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Figure 12. Typical section of an im-permeable, steel sheet pile groin

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Figure 13. Impermeable, steel sheet pile groin; Rehoboth Beach, Delaware

Figure 14. Impermeable, steel sheet pile groin, using a cantilever wall design; Presque Isle Peninsula, Pennsylvania

Figure 15. Impermeable, steel sheet pile crib groin-

--connect to shore with a cantilever wall; Muskegon, Michigan

Figure 16. Impermeable, steel sheet pile groin, constructed in a zigzag

pattern; South Haven, Michigan

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Figure 18. Impermeable, cellular steel groin; Presque Isle Peninsula, Pennsylvania

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Figure 19. Typical section of an

Figure 20. Impermeable, timber groin; Cape May, New Jersey

Figure 21. Impermeable, timber block groin, similar to C. T. Leed's Design; Westport, Connecticut

Figure 22. Impermeable, asphalt groin; Harvey Cedars, New Jersey

Figure 24. Impermeable, stone-rubble mound groin; Presque Isle Pen-insula, Pennsylvania

Figure 26. Impermeable, concrete filled oil drums groin, Indian Creek, Ohio

Figure 27. Impermeable, stone filled, timber crib groins; Fort Niagara,

Figure 28. Impermeable, oyster shell cluster groins; Bay St. Louis, Hancock County, Mississippi

Figure 29. Impermeable, stone-rubble mound groins, constructed in a T shape; Elberon, New Jersey

Figure 30. Impermeable, stone-rubble mound groins, constructed with an outer hook; Ocean City, New Jersey

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Figure 31. Typical section of a permeable

con-crete groin of a Budd-Wall design

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Figure 32. Permeable, concrete groin,

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Figure 33. Typical section of a permeable, concrete groin

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Figure 34. Permeable, concrete groin of the design shown in Figure 33; Bradford Beach, Milwaukee, Wisconsin

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Figure 35. Typical section of a permeable, con-crete groin

Figure 36. Permeable, concrete groin of the design shown in Figure 35;

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CONCRETE PERMEABLE GROIN (SYONEY M. WOOD)

Figure 37. Typical section of a permeable,

con-crete groin of a S. M. Wood design

Figure 38. Permeable, concrete groin of a S. M. Wood's design, without deck sections; Milwaukee, Wisconsin

Figure 39. Permeable, concrete groin of a S. M. Wood design, with deck section; Perkins Beach, Cleveland, Ohio

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Figure 41. Permeable, concrete groin of the design shown in Figure 40; Palm

Beach, Florida

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Figure 42. Permeable, concrete pipe groin, with a

CLEARWATER BEACH PIER-GROIN

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Figure 43. Typical section of permeable, concrete fishing pier/groin

Figure 44. Permeable, concrete fishing pier/groin; Clearwater Beach, Florida

Figure 45. Permeable, steel sheet pile groin; Highland Park, illinois

Figure 46. Permeable, timber groin; Sand Hill Cove, Point Judith, Rho

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Figure 47. Permeable, timber groin; Ocean City, New Jersey

Figure 49. Detail photograph of the groin shown in Figure 4~.

Figure 50. Permeable, palmetto timber groin; Edisto Beach, South Carolina

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