GB769861A - Improvements in or relating to the construction of groynes - Google Patents

Abstract

769,861. Groynes. HUNTER, E. T. June 15, 1955 [Oct. 18, 1954], No. 17265/55. Class '68 (2). A groyne for erection on beaches for the control of coastal erosion by tidal waters com- 'prises a plurality of plate-like units 'A each having, on one face, transverse spacer ribs 2, 3, 4 provided with shouldered projections 5, and a similar number of apertures 6 having greater cross-sectional area than the projections 5 so that when the units are arranged, e.g. by a crane, contiguously to each other and rearwardly inclined regarding the sea to form a groyne, as shown, the projections fit loosely within the apertures thus enabling each unit to move both laterally and vertically relative to the adjacent units. The groyne is built up from a suitable base such as a block B which is constructed, e.g. of concrete, in a stabilized area of the beach, the outer edge of the block being provded with ribs and projections similar to those on the units A. Steel rods 7 are embedded in the projections 5 on the block B and the units A, the rods being bent upwardly, or laterally, after the projections have been engaged in the corresponding recesses of adjacent units to prevent the units from moving seawards of the base block. After the required number of units have been assembled an end cap C is fitted which is flat on both faces and has apertures which fit the projections of the last preceding unit A. Enlarged units, shown in broken lines Fig. 3 are used where the offshore profile is irregular. In a modification, Fig. 7, notches 21, 21<SP>1</SP> are provided in the tops of the units 13 and B<SP>1</SP> respectively and a top cap 23 with, or without, reinforcing rods 24, is cast between wooden forms 22 fastened to the sides of the groyne, the inclined sides 19 of each upper spaced rib permitting the laying of the forms 22 flush against the sides of the groyne. Vertical ribs may be provided with this type of unit.