Common use of Filling and Placement Clause in Contracts

Filling and Placement. The foundation for each gabion and mattress shall be prepared by the Contractor to the satisfaction of the Engineer. Irregularities in the foundation shall be excavated or tightly filled with gravel to produce a surface which has no protrusions or cavities in excess of 100 mm. The gabions and mattresses shall be flexible galvanised gabions of the size shown on the Drawings and shall be fabricated from wire mesh. Each gabion and mattress shall be divided by diaphragms into cells, whose length shall not be greater than the width of the gabions or mattresses plus 100 mm. The gabion and mattress boxes shall be fabricated 'Maccaferri' type or equivalent supplied by an approved manufacturer. The prefabricated gabions and mattresses shall be obtained complete with sufficient suitable galvanised wire for completing the wiring of the gabions and mattresses on Site. The wire in the gabions and mattresses shall be galvanised similar to or stronger than that used in 'Maccaferri' galvanised gabions. The wires in the gabions and mattresses shall be arranged so that the spacing between the wires is similar to or smaller than in 'Maccaferri' gabions and mattresses. The empty gabions shall be placed to line and level as shown on the Drawings or as directed by the Engineer and then stretched so that the gabions regain their shape on being filled. Diaphragms shall be provided at not more than one metre (1 m) intervals for baskets and not more than 1.2 metre intervals for mattresses. A gabion shall not be completely filled until the adjacent basket or mattress has been half filled, unless otherwise directed, in order not to cause displacements from bulging during filling. Because of small horizontal movements associated with the settlement or consolidation, gabion walls must not be constructed with a vertical front face as it subsequently tilts forward slightly. All gabion walls must be constructed with the front face at the slight angle to the vertical (10:1 – vertical: Horizontal). This should be achieved by sloping the foundation accordingly as shown in the diagram below: Before filling, adjacent baskets should be secured together using steel lacing wire provided for the purpose and conforming to the specification. The sides must be secured in straight lines with no gaps left between the sides of adjacent baskets. Where more than one layer of baskets is laid, they must be placed as shown on the Drawings or as directed by the Engineer with a minimum step of 0.15 m between the faces of the lower and upper gabion boxes. All gabions must be connected to each other along corners with the same lacing operation. For correct lacing operation, the wire should be passed through each mesh, making a double twist every other mesh. Careful attention must be given to the filling operation to ensure that the stones are placed evenly in the baskets with minimum voids in between. Smaller stones can be used to fill the central voids of the boxes, but all external stones must be at least 1.5 D where D is the diameter of the mesh. The stones selected for the top layer of gabion baskets must have a flat surface to ensure that the wire that does not rest on sharp corners. They must have a minimum dimension of 1.5 D in all directions and be placed to ensure a minimum number of voids. Bracing wires must be fixed at depths of 1/3H where “H” is the height of the gabion box. The horizontal distance between the bracing wires should also be 1/3H thus for a gabion basket of 2m x 1m x 1m dimension, eight bracing wires are provided. For the gabion boxes used on the project the bracing wires should be placed at the following depths and spacing. Gabion Dimensions Depth of Bracing Wire from bottom of gabion Horizontal Distance Between Bracing Length Width (m) (m) Depth (m) 1st Brace 2nd Brace (meters) 0.40 0.80 1.20 1.60 2.00 1.00 1.00 0.35 0.70 0.35 0.70 - 1.00 1.00 1.00 0.35 0.70 - 2.00 1.00 0.50 0.25 - 0.40 0.80 1.20 1.00 1.00 0.50 0.25 - 1.60 0.35 0.70 - - Stones should be filled to the depth of the first brace and then the bracing wires placed directly above the level of the stone making sure the wire passes around at least two mesh widths. The procedure should then be followed for the next layer. In aprons downstream of weirs and similar places where water falls directly on to the gabions, vertical bracing wires between the top and bottom mesh must be provided. Additional horizontal bracing must be used at the corners of structure.

Filling and Placement. The foundation for each gabion and mattress shall be prepared by the Contractor to the satisfaction of the Engineer. Irregularities in the foundation shall be excavated or tightly filled with gravel to produce a surface which has no protrusions or cavities in excess of 100 mm. The gabions and mattresses shall be flexible galvanised gabions of the size shown on the Drawings and shall be fabricated from wire mesh. Each gabion and mattress shall be divided by diaphragms into cells, whose length shall not be greater than the width of the gabions or mattresses plus 100 mm. The gabion and mattress boxes shall be fabricated 'Maccaferri' type or equivalent supplied by an approved manufacturer. The prefabricated gabions and mattresses shall be obtained complete with sufficient suitable galvanised wire for completing the wiring of the gabions and mattresses on Site. The wire in the gabions and mattresses shall be galvanised similar to or stronger than that used in 'Maccaferri' galvanised gabions. The wires in the gabions and mattresses shall be arranged so that the spacing between the wires is similar to or smaller than in 'Maccaferri' gabions and mattresses. The empty gabions shall be placed to line and level as shown on the Drawings or as directed by the Engineer and then stretched so that the gabions regain their shape on being filled. Diaphragms shall be provided at not more than one metre (1 m) intervals for baskets and not more than 1.2 metre intervals for mattresses. A gabion shall not be completely filled until the adjacent basket or mattress has been half filled, unless otherwise directed, in order not to cause displacements from bulging during filling. Because of small horizontal movements associated with the settlement or consolidation, gabion walls must not be constructed with a vertical front face as it subsequently tilts forward slightly. All gabion walls must be constructed with the front face at the slight angle to the vertical (10:1 – vertical: Horizontal). This should be achieved by sloping the foundation accordingly as shown in the diagram below: Before filling, adjacent baskets should be secured together using steel lacing wire provided for the purpose and conforming to the specification. The sides must be secured in straight lines with no gaps left between the sides of adjacent baskets. Where more than one layer of baskets is laid, they must be placed as shown on the Drawings or as directed by the Engineer with a minimum step of 0.15 m between the faces of the lower and upper gabion boxes. All gabions must be connected to each other along corners with the same lacing operation. For correct lacing operation, the wire should be passed through each mesh, making a double twist every other mesh. Careful attention must be given to the filling operation to ensure that the stones are placed evenly in the baskets with minimum voids in between. Smaller stones can be used to fill the central voids of the boxes, but all external stones must be at least 1.5 D where D is the diameter of the mesh. The stones selected for the top layer of gabion baskets must have a flat surface to ensure that the wire that does not rest on sharp corners. They must have a minimum dimension of 1.5 D in all directions and be placed to ensure a minimum number of voids. Bracing wires must be fixed at depths of 1/3H where “H” is the height of the gabion box. The horizontal distance between the bracing wires should also be 1/3H thus for a gabion basket of 2m x 1m x 1m dimension, eight bracing wires are provided. For the gabion boxes used on the project the bracing wires should be placed at the following depths and spacing. Gabion Dimensions Depth of Bracing Wire from bottom of gabion Horizontal Distance Between Bracing (meters) Length Width (m) Width (m) Depth (m) 1st Brace 2nd Brace (meters) 0xx Xxxxx 0xx Xxxxx 0.40 0.80 1.20 1.60 2.00 1.00 1.00 0.35 0.70 0.35 0.70 - 1.00 1.00 1.00 0.35 0.70 - 2.00 1.00 0.50 0.25 - 0.40 0.80 1.20 1.00 1.00 0.50 0.25 - 1.60 0.35 0.70 - - Stones should be filled to the depth of the first brace and then the bracing wires placed directly above the level of the stone making sure the wire passes around at least two mesh widths. The procedure should then be followed for the next layer. In aprons downstream of weirs and similar places where water falls directly on to the gabions, vertical bracing wires between the top and bottom mesh must be provided. Additional horizontal bracing must be used at the corners of structure.