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Introduction to Gabion Construction. 9.
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Introduction to Gabion Construction 9 This training was prepared by the U.S. Department of Agriculture (USDA) team of Otto Gonzalez-USDA Foreign Agricultural Service (Team Leader), Jon Fripp (Civil Engineer) and Chris Hoag (Wetland Plant Ecologist)-USDA Natural Resources Conservation Service (Civil Engineers). Fripp and Hoag were the primary authors of this material. The U.S. AID provided funding support for the USDA team.
Check Dams can be built with many different types of materials • Rock • Logs • Metal • Concrete • Gabions • others Gabions are also good to use if:1 - A required stone or riprap size is larger than what is available.2 - A vertical wall is needed
What is a gabion? Answer: A gabion is a big wire box full of small stone.
The Basket is construct so it can be folded into a box • Edges need thicker wire (hem) Hem
Woven wire should be 0.3 cm (0.115 inch) thick • Woven opening should be 8 to 12 cm • Hem should be 0.4 cm (0.153 inch) thick • Should not exceed 1 m without an inside wall Inside wall
Assembly of the baskets includes fastening the edges and inside wall before placing
Lace the hems on the sides with wire Double half-hitches at spacing between 8 to 15 cm. Lacing wire is 0.2 cm
LACING WIRE The hems must be tightly held together
DOUBLE HALF HITCH Double Half Hitch Clove Hitch
LACING BASKETS WITH WIRE NOT this!
Unless you have a big crane, it is best to place the basket then fill with stone
Stone Size The stone must be larger than the opening of the wire mesh
These stones are too small The basket may not hold them
Can use smaller stone in middle • But the stones on the outside must larger than the opening • Workers may mix this up so be careful. Need good supervision
Fill in layers • Place internal wires every 0.5 meter
Place Stones carefully on the outside so that the face is uniform.Basket should be full but not buldging
Assemble Gabions Like a Brick Wall Like this
Test time! Do you see anything wrong in this picture? Answer: lacing
Do you see anything wrong in this picture? Answer: Rock size too small on surface
What is the problem here? Answer: not filled completely, also some rocks are too big and some too small
Do you see anything wrong in this picture? Answer: Nothing, but joints are close, but overlapping joints are hard to achieve
Do you see anything wrong in this picture? Answer: Nothing, good joints, rock size, fill