Gabions River Training Works

In this page, we introduce steps of fabrication of gabion boxes ( including placement of gabion box, filling requirements, measurement of gabions works), bank protection layout on sites, construction of levees, platforms and channels realignments. All these works are basic for the bridge construction project along riverside.

Box Shaped Gabions Cells

FABRICATION OF GABIONS:

Step 1. Stretching: The gabions shall be unfolded on the ground and stretched to the
maximum extent possible while ensuring that all creases are in the correct positions for forming the box.

Step 2. Cutting: Any cutting required shall be carried out so that the cut ends of wire are a minimum of 50 millimetres from the twisted joins. After stretching and cutting as required the side and end panels shall be lifted so that the tops of all sides are level. Any loose ends of wire protruding above a level plane at the top or from the corners shall be bent down into the gabion box.

Step 3. Fastening and Lacing: Corners shall be fastened securely and the box shaped prior to commencing any binding. The binding wire shall be securely fastened to the top of a corner by lacing between two meshes at the corner and twisting the binding wire through three half turns. The wire shall then be laced around the two vertical selvedges, when applicable, and through each mesh in turn in a continuous lacing action and shall be pulled tight before securing to the bottom corner by the three half turns to an adjacent wire.

Step 4. Positioning of gabion boxes before filling: The diaphragm panels shall then be placed in position and secured to the gabion sides in the same manner as the corners. The empty box shall then be firmly seated on a prepared area in its final position and laced to the adjoining corners or sides of gabions previously placed along all adjoining corners and tops. If additional binding of the gabions is required this shall be shown on the Drawings or specified.

Placement of the Gabion Boxes:
The placement of the gabion boxes shall be carried out in an orderly manner so that a face of uncompleted work is maintained. At least two rows of empty boxes shall be wired together at the face of uncompleted work prior to filling the box closest to the completed work.

Prior to filling any box one end or side of the box shall be secured to completed works or to stakes driven into the ground at the corners or in any other approved manner and the opposite end, side or corner shall be stretched with crowbars and secured top and bottom in an approved manner.

Filling Boxes
When boxes used are one (1) metre high or more they shall be cross tensioned in each compartment at third points in the height by wires of the same diameter as the binding wire securely tied by two turns around the mesh or selvedge wire and three half turns around itself.

The gabions wire boxes shall be filled to between 25 and 50 millimetres above their
tops. The lids shall be stretched tight over the filling with a crow-bar or similar and wired down in a continuous lacing process in the same manner as that specified for corners. Each edge may be laced with a separate length of binding.

Measurement of Gabion Works

The Gabions shall include for all work specified including excavation, filling, compaction and trimming necessary to construct the gabions to the lines and levels specified. Measurement of the quantity in cubic metres will be made shall be based on the nominal external dimensions of the gabion baskets which have been constructed in accordance with the Contract. The unit of measurement for Reno mattresses shall be the cubic metre (m3).

BANK PROTECTION WORKS
Bank protection works are carried out with gabions and mattresses. The gabions and mattresses shall not be placed until the bank has been trimmed and compacted to the satisfaction of the Engineer.

The front line of gabion works is intended to break the force of the river and cause deposition. Unless otherwise directed by the Engineer they shall be placed at a level with their tops approximately 600 mm above the river's normal flow level.

We also supply chain link mesh fences placed generally to the lines or as directed by the Engineer. They are intended to act as a debris trap. Adequate numbers of cuttings shall be planted to provide long term protection, these shall be placed to the direction of the Engineer. The cuttings shall be of a type known to grow strongly, with heavy root growth, in moist ground conditions, in the area in which the works are being carried out.

We also supply piles as part of the protection requirements.

CONSTRUCTION OF LEVEES, PLATFORMS FOR RIVER TRAINING WORKS AND THE REALIGNMENT OF CHANNELS

Levees and platforms for river training works shall be constructed with above fabrication of gabions cells. Before work commences, a survey shall be carried out to permit measurement. Realignment of channels and reshaping of river channels adjacent to bridges shall be carried out as directed by the Engineer.

RIVER CHANNELS MEASUREMENT:
Realignment of channels and re-shaping of river channels adjacent to bridges shall be measured in a manner approved by the Engineer to enable the quantity to be calculated in cubic metres (m3).

The unit of measurement for the construction of levees and platforms
for river training works shall be the cubic metre (m3).

The unit of measurement for fences shall be linear metre and shall
include for the star pickets and wire ropes.

The unit of measurement for wire aprons shall be the square metre
(m2).
The unit of measurement for piles shall be number of given length and
shall include the supply of piles, the provision of plant and pitching
and driving the piles.

The unit of measurement for tripods of cuttings shall be number.