Procedure

Procedure

Construction Sequence for Bagwork-Faced walls with a Wrap-around face

1.Prepare a level foundation (Well compacted Ground) as required in preparation for the laying of the first Geogrid Layer.

2.Cut and position the base layer of grid leaving the wrap-around grid length proud of wall face. Grids should be installed to the level, lengths and orientation as shown in the Construction drawings.

3.Place two or three courses of bags which have been filled with garden soil.

4.Place a quantity of fill on the grid close to the rear of the bags, pull the grid or stretch it tightly at the free end and secure with fill.

5.Place and compact fill in layers behind bagwork (95% compaction) to the level of the next layer.

Compact to DoT Specification for Highway Works (2001). Use a vibrating plate compactor or a vibrating roller with a mass per meter width = 1000kg.

6.Fold the wrap-around grid length around the bagwork (at specified distance of each layer of the grid) and lay it over the surface of the fill.

7.Cut and position the next layer of grid. Form a joint between this and the ower grid length (see figure) using a suitable bodkin (see bodkin for specification detail).

8.Apply a load to the free end of the upper grid, using a wooden pegs inserted through the apertures of the geogrids, until the slack is removed from the joint and the lower grid is pulled tight around the bag.

9.While maintaining tension, place a layer of fill on the grid which will be sufficient to restrain it when the load is removed.

10.Repeat the sequence up to the design height of the structure.

11.The top layer of grid is provided with a longer wrap-around length which is secured by burying beneath the top surface with sufficient surcharge to restrain it permanently ( see main figure).

12.The contractor must carefully assess the safety risk associated with working at height and where appropriate install any necessary temporary edge protection.

Construction Sequence for Block facing walls

1.Prepare the leveling pad and lay the base course of the blocks, ensure that the units are level front to back, side to side and to the correct alignment. Align the blocks with a string line placed on top of the blocks. Allow the mortar bed to cure before laying additional courses.

2.Place a quantity of drainage layer at the back of the blocks and place a geotextile to ensure separation fill and drainage layer. Place fill up to the layer of reinforcement and compact (95% compaction).

3.Stretch the embedded “tail” of the Geogrid and fastened it to the reinforcement layer using a Bodkin (as shown in the drawings).


(Bodkin connection to the reinforcement layer)

4.Stretch the “tail” of the reinforcement to the design anchorage length and place wooden peg to ensure tension. Place a quantity of fill up to the next layer of reinforcement and compact (95% compaction).

5 .Repeat steps 2, 3 and 4 up to the design height of the wall.




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