8.5.4 Placement and compaction of fill
8.5.4.1 Placement and compaction of fill shall be executed with great care as the performance of a reinforced fill structure is mainly influenced by the nature of the backfill and the consistent manner in which it is placed and compacted.
8.5.4.2 Prior to the commencement of construction a method for compaction of the fill shall be established which, if specified, may include field trials.
8.5.4.3 Equipment compatible with the proposed method shall be provided to achieve the compaction requirements set up by the design
8.5.4.4 The grading and the moisture content of the fill material shall be checked periodically during construction to assure compliance with the design specifications, especially whenever the appearance or behaviour of the material changes noticeably.
8.5.4.5 The deposition, spreading, levelling and compaction of the fill should be carried out generally in a direction parallel to the facing or the sloped face.
8.5.4.6 Care shall be taken to ensure that the reinforcing elements and the facing, if any, are not damaged during deposition, spreading, levelling and compaction of the fill. No machines or vehicles shall run directly on the reinforcements.
8.5.4.7 All vehicles, and all construction equipment weighing more than 1500 kg shall be kept at least 1m away from the facing or the face of slopes without facing.
8.5.4.8 The thickness of the layers of backfill shall be within the limits specified by the design and such that it allows compaction to the required density. It should be a sub-multiple of or equal to the vertical reinforcement spacing.
8.5.4.9 Specific care shall be taken for the compaction of the fill near the facing, if any, to avoid any damages of the facing elements and the connected reinforcements and to minimize deformations. Special attention shall be paid to confined spaces, such as the corners of a structure.
8.5.4.10 The fill within 1 m of the face may be compacted using adequate light compaction equipment. Where small compaction equipment is used, the thickness of the layers shall be adjusted as needed to obtain the compaction requirements
8.5.4.11 At the end of each day's work the surface of the compacted fill should be left at a slight inclination (2 % – 4 %) away from the facing or the sloped face and sealed with a smooth compactor to ensure that any surface water is guided away to a suitable outlet.
8.5.4.12 The rear of the structure should be backfilled by phasing the work in order to ensure the contemporaneous deposition of the retained fill material.
8.5.4.13 The sequence of fill placement over soft or ultra soft ground may be specified within the design. If not, care should be taken to ensure that the sequence of filling, including any trafficking by construction plant, at no time exceeds the bearing capacity of the underlying ground.
8.5.5 Vegetative cover to the face (greened surface)
8.5.5.1 For permanent reinforced fill structures meant to have a permanent vegetative cover on the facing, the relevant specifications of the design shall be thoroughly met. Moreover, careful attention should be paid to any special construction guidelines of the supplier of the system.
8.5.5.2 If the characteristics of the backfill material are not adequate to support vegetation, suitable topsoil material may be placed at the front face separated from the fill, if necessary, by an appropriate geotextile.
8.5.5.3 The climatic and local conditions (such as site location, cardinal points, aspect, altitude, amount and frequency of precipitation) shall be taken into account, together with the slope angle, since they may influence the choice of a suitable:
- soil type in the face area
- seed or plant assortment
- greening method (hydroseeding, seeded geosynthetics, plants, etc.) or the necessity of artificial irrigation.
