GENERAL INFORMATION :
1. P o t e n t i a l Benefits :
A. Low cost. Gabions can be more economical for shore protection than
riprap because they require smaller size stone. Small stone would negate the
need for heavy construction equipment.
I n areas where large stone is not
r e a d i l y available, t h e use of small stone could mean a substantial cost
savings.
B. E a s e of Installation. Gabions can be installed without specialized
skills or equipment. A crane or front-end loader, to fill the baskets with
stone and move them into place, may be the only major equipment required.
Bundles of gabion wire mesh are unfolded at the construction site and
assembled by lacing the diaphragms to the side panels and joining the edges
together.
T h e diaphragms restrict internal movement of the rock fill and
r e i n f o r c e the structure. T y i n g the gabion units together vertically and
h o r i z o n t a l l y , provides structural strength and integrity. Failure to tie the
gabions together may cause premature structure failure. Bedding and filter
m a t e r i a l , such as geotextile fabric or gravel , should be placed between the
s o i l foundation and the gabions to function as an underlayer and to provide
a d e q u a t e subsurface drainage without leaching. Toe protection is also
important. U s e of additional quarrystone to act as toe protection should help
prevent scour problems.
Once in place, t h e gabions are ready to be filled with stone. The
g r a d a t i o n should be uniform and sufficiently large to prevent individual
stones from being washed through the wire mesh. The stone should also be small
enough to facilitate even placement with minimal void space,
Major stone
movement or loss would cause gabion deformation and eventual rupture of the
wire due to abrasion. T h e ideal stone for gabion use is rounded, has a high
s p e c i f i c gravity, and ranges in size from 12 to 25 cm (approximately 5 to 10
in.), depending on mesh size. It is important to fill the gabions completely
w i t h stone, packing tightly to minimize flexing. Some manual shifting of the
stones may be necessary for optimal placement and performance. Once the
gabions are filled, the lids are tied closed. T i e r s or levels can be formed by
s t a c k i n g , filling, and tying the gabions together. The time saved in not
l a c i n g the units according to specifications will be offset by shortened
s t r u c t u r e lifespan.
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