SIST EN 14475:2006
(Main)Execution of special geotechnical works - Reinforced fill
Execution of special geotechnical works - Reinforced fill
1.1 This European Standard establishes general principles for the construction of reinforced fill.
1.2 This European Standard covers engineered fills that are reinforced by the inclusion of horizontal or sub-horizontal reinforcement placed between layers of fill during construction.
1.3 The scope of reinforced fill applications considered in this European Standard includes (Figure 1):
- earth retaining structures, (vertical, battered or inclined walls, bridge abutments, bulk storage facilities), with a facing to retain fill placed between the reinforcing layers;
- reinforced steep slopes with a facing, either built-in or added or wrap-around, reinforced shallow slopes without a facing, but covered by some form of erosion protection without a facing, reinstatement of failed slopes;
- embankments with basal reinforcement and embankments with reinforcement against frost heave in the upper part.
Principles for the execution of other special geotechnical works using soil nails, bored piles, displacement piles, micro piles, sheet pile walls, diaphragm walls, grouting or jet grouting are established in other European Standards.
Reinforcement of road pavements is not covered by this Standard.
Ausführung von besonderen technischen Arbeiten (Spezialtiefbau) - Bewehrte Schüttkörper
1.1 Diese Europäische Norm legt die allgemeinen Grundsätze zur Ausführung bewehrter Schüttkörper fest.
1.2 Diese Europäische Norm umfasst ingenieurmäßig hergestellte Schüttkörper, die durch Einlage von horizontalen oder nahezu horizontalen Bewehrungen zwischen die Schichten der Schüttung errichtet werden.
1.3 Der Anwendungsbereich von bewehrten Schüttkonstruktionen nach dieser Europäischen Norm umfasst (siehe Bild 1):
- Erdstützkonstruktionen (senkrechte, abgestufte oder geneigte Wände, Brückenwiderlager, Schüttgutlager) mit einer Frontausbildung zur Rückhaltung des Schüttmaterials, das zwischen den Bewehrungs-lagen eingebaut wird;
- bewehrte Steilböschungen mit Frontausbildung, entweder im Schüttkörper integriert oder ihm vorgesetzt oder als Polsterwände, flache bewehrte Böschungen ohne Frontausbildung, aber mit oberflächigem Erosionsschutz und die Wiederherstellung gerutschter Böschungen;
- Dämme mit Sohlbewehrung und Dämme mit Bewehrungen zur Verhinderung von Frosthebungen im oberen Bereich.
Grundsätze der Ausführung anderer spezieller geotechnischer Arbeiten unter Verwendung von Vernagelungen, Bohrpfählen, Verdrängungspfählen, Kleinbohrpfählen, Spundwänden, Schmaldichtwänden, Injektionen und Düsenstrahlverfahren werden in anderen Europäischen Normen geregelt.
Exécution de travaux géotechniques spéciaux - Remblais renforcés
1.1 La présente Norme européenne établit les principes généraux pour la construction des ouvrages en remblai renforcé.
1.2 La présente Norme européenne s’applique aux remblais techniques renforcés par l’inclusion de renforcements horizontaux ou sub-horizontaux placés entre les couches du remblai au cours de leur construction.
1.3 Le domaine d’application des remblais renforcés examinés dans la présente Norme européenne comprend (Figure 1) :
- les ouvrages de soutenement (murs verticaux, murs peu ou tres inclinés, culées de pont, structures de stockage en vrac), comportant un parement qui permet de retenir le remblai placé entre les lits de renforcement ;
- les talus renforcés tres inclinés avec un parement, soit intégré, soit rapporté, ou bien enveloppant les couches de remblai, les talus renforcés peu inclinés, sans parement, mais recouverts d’une simple protection contre l’érosion, et la réparation des glissements de talus ;
- les remblais renforcés a la base, et les remblais renforcés en partie supérieure contre les soulevements provoqués par le gel.
1.4 Les principes relatifs a l’exécution d’autres travaux géotechniques spéciaux tels que le clouage des sols, les pieux forés, les pieux avec refoulement du sol, les micropieux, les rideaux de palplanches, les parois moulées, les injections et les colonnes de sol-ciment réalisées par jet sont traités dans d’autres normes européennes.
Le renforcement des chaussées routieres n’est pas couvert par la présente norme.
Izvedba posebnih geotehničnih del – Armirano polnilo
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Execution of special geotechnical works - Reinforced fillExécution de travaux géotechniques spéciaux - Remblais renforcésAusführung von besonderen technischen Arbeiten (Spezialtiefbau) - Bewehrte Schüttkörper93.020Zemeljska dela. Izkopavanja. Gradnja temeljev. Dela pod zemljoEarthworks. Excavations. Foundation construction. Underground worksICS:SIST EN 14475:2006enTa slovenski standard je istoveten z:EN 14475:200601-junij-2006SIST EN 14475:2006SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14475January 2006ICS 93.020 English VersionExecution of special geotechnical works - Reinforced fillExécution de travaux géotechniques spéciaux - RemblaisrenforcésAusführung von besonderen technischen Arbeiten(Spezialtiefbau) - Bewehrte SchüttkörperThis European Standard was approved by CEN on 10 November 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14475:2006: E
EN 14475:2006 (E) 2 Contents
page Foreword.3 1 Scope.4 2 Normative references.6 3 Terms and definitions.8 4 Information needed for construction.10 5 Geotechnical investigations.10 6 Materials and products.11 7 Design considerations.17 8 Execution.20 9 Supervision, testing and monitoring.27 10 Records.27 11 Specific requirements.28 Annex A (informative)
Typical use of fill types depending on application, reinforcement and facing.29 Annex B (informative).30 Annex C (informative)
Facing units and systems.32 Annex D (informative)
Some typical reinforcement forms.49 Annex E (informative)
Steel reinforcement.52 Annex F (informative)
Recommendations for facing units.54 Bibliography.56
EN 14475:2006 (E) 3 Foreword This document (EN 14475:2006) has been prepared by Technical Committee CEN/TC 288 “Execution of special geotechnical works”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2006, and conflicting national standards shall be withdrawn at the latest by July 2006. The design of reinforced fill structures is currently carried out using national standards such as BS 8006 (1995) and NF P 94-220 (1998) and other standards. As a matter of fact EN 1997-1, Eurocode 7 (Geotechnical design) does not currently cover the detailed design of reinforced fill structures. The values of partial factors and load factors given in EN 1997-1 have not been calibrated for reinforced fill structures. Whilst many common features exist between the design methods that have been developed and established in the various member countries of CEN, there are also differences reflecting different working practices, as well as such matters as geological and climatic variations. In view of these differences, and of the time required to develop a common design method that would fully reflect the various considerations identified in particular national methods, a two stage approach has been adopted for the development of standards for reinforced fill. In accordance with this two stage approach Working Group 9 was mandated by TC 288 for first producing an EN giving guidance on the Execution of reinforced fill, before working towards a common method of design. This standard represents the implementation of the first part of that mandate. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EN 14475:2006 (E) 4 1 Scope 1.1 This European Standard establishes general principles for the construction of reinforced fill. 1.2 This European Standard covers engineered fills that are reinforced by the inclusion of horizontal or sub-horizontal reinforcement placed between layers of fill during construction. 1.3 The scope of reinforced fill applications considered in this European Standard includes (Figure 1): earth retaining structures, (vertical, battered or inclined walls, bridge abutments, bulk storage facilities), with a facing to retain fill placed between the reinforcing layers; reinforced steep slopes with a facing, either built-in or added or wrap-around, reinforced shallow slopes without a facing, but covered by some form of erosion protection without a facing, reinstatement of failed slopes; embankments with basal reinforcement and embankments with reinforcement against frost heave in the upper part. Principles for the execution of other special geotechnical works using soil nails, bored piles, displacement piles, micro piles, sheet pile walls, diaphragm walls, grouting or jet grouting are established in other European Standards. Reinforcement of road pavements is not covered by this Standard.
EN 14475:2006 (E) 5
a) Walls b) Abutments c) Mixed abutments
d) Reinforced slopes
e) Basal reinforcement f) Basal mattress Key Key 1 Reinforcement 2 Soft deposit 1 Thin soft layer 2 Firm layer
EN 14475:2006 (E) 6
g) Piled embankments with basal reinforcementh) Reinforcement over areas prone to subsidence Key Key 1 Reinforcement 2 Piles 1 Reinforcement 2 Potential weak zones or voids
i) Reinforcement in areas prone to frost heave j) Offshore Basal Reinforcement Key Key 1 Reinforcement 2 Ice lenses 1 Reinforcement 2 Lake or sea 3 Soft seabed Figure 1 — Some reinforced fill applications 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 206-1, Concrete – Part 1: Specification, performance, production and conformity. EN 1990, Eurocode – Basis of structural design. EN 1991, Eurocode 1 : Actions on structures. EN 1992-1-1, Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules for buildings
EN 14475:2006 (E) 7 EN 1997-1, Eurocode 7: Geotechnical design
- Part 1: General rules EN 10025-2, Hot rolled products of structural steels – Part 2: Technical delivery conditions for non-alloy structural steels. EN 10025-4, Hot rolled products of structural steels – Part 4: Technical delivery conditions for thermomechanical rolled weldable fine grain structural steels. EN 10079, Definition of steel products. EN 10080, Steel for the reinforcement of concrete - Weldable reinforcing steel - General EN 10218-1, Steel wire and wire products – General - Part 1 : Test methods. EN 10218-2, Steel wire and wire products - General - Part 2 : Wire dimensions and tolerances. EN 10223-3, Steel wire and wire products for fences - Part 3 : Hexagonal steel wire netting for engineering purposes. EN 10223-4, Steel wire and wire products for fences - Part 4 : Steel wire welded mesh facing.
EN 10244-1, Steel wire and wire products - Non-ferrous metallic coatings on steel wire - Part 1: General principles. EN 10244-2, Steel wire and wire products - Non-ferrous metallic coatings on steel wire - Part 2: Zinc or zinc alloy coatings.
EN 10245-1, Steel wire and wire products - Organic coatings on steel wire – Part 1: General rules.
EN 10245-2, Steel wire and wire products - Organic coatings on steel wire – Part 2: PVC finished wire.
EN 10245-3, Steel wire and wire products - Organic coatings on steel wire – Part 3: PE coated wire. EN 10326, Continuously hot-dip coated strip and sheet of structural steels – Technical delivery conditions.
EN 12224, Geotextiles and geotextile-related products – Determination of the resistance to weathering. EN 12225, Geotextiles and geotextile-related products – Method for determining the microbiological resistance by a soil burial test.
EN 13251, Geotextiles and geotextile-related products - Characteristics required for use in earthworks, foundations and retaining structures. EN ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel - Part 1: Bolts, screws and studs (ISO 898-1:1999) EN ISO 1461, Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and test methods (ISO 1461:1999) EN ISO 2063, Thermal spraying - Metallic and other inorganic coatings - Zinc, aluminium and their alloys (ISO 2063:2005) EN ISO 10320, Geotextiles and geotextile-related products – identification on site (ISO 10320:1999). ENV ISO 10722-1, Geotextiles and geotextile-related products - Procedure for simulating damage during installation - Part 1: Installation in granular materials (ISO 10722-1:1998)
EN 14475:2006 (E) 8 EN ISO 12957-1, Geosynthetics - Determination of friction characteristics - Part 1: Direct shear test (ISO 12957-1:2005) EN ISO 13431, Geotextiles and geotextile-related products - Determination of tensile creep and creep rupture behaviour (ISO 13431:1999)
3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 fill natural or man made material formed of solid particles, including certain rocks, used to construct engineered fill 3.2 reinforcement generic term for reinforcing inclusions placed within fill 3.3 engineered fill fill which is placed and compacted under controlled conditions 3.4 reinforced fill engineered fill incorporating discrete layers of soil reinforcement, generally placed horizontally, which are arranged between successive layers of fill during construction 3.5 fill reinforcement reinforcement which enhances stability of the reinforced fill mass by mobilising the axial tensile strength of the fill reinforcement by soil interaction over its total length NOTE It is typically in the form of a strip, sheet, rod, grid or mesh and is usually placed in discrete layers. 3.6 geosynthetics for the purpose of this European standard “geosynthetics” stands for “geotextiles and geotextile related products” 3.7 facing covering to the exposed face of a reinforced fill structure which retains the fill between layers of reinforcement and protects the fill against erosion 3.8 foundation foundation of a reinforced fill structure is the total area of the surface upon which the lowest layer of reinforcement is installed 3.9 discrete facing unit partial height facing unit used to construct incrementally a reinforced fill structure
EN 14475:2006 (E) 9 3.10 full height facing unit facing unit equal to the height of the face of the structure 3.11 hard facing unit panel or block usually of precast concrete with intrinsically low vertical compressibility and high bending stiffness. (See C.2.1 for guidance) 3.12 deformable facing unit preformed steel grid section, a preformed solid steel section or a rock filled gabion with intrinsically vertical compressibility and low bending stiffness. (See C.2.2 for guidance) 3.13 soft facing unit soil fill encapsulated in a geogrid or a geotextile facing with no bending stiffness. (See C.2.3 for guidance) 3.14
facing system assemblage of facing units used to produce a finished reinforced fill structure 3.15 rigid facing system facing system with no capacity to accommodate vertical differential settlement between fill and facing. (See Annex C for guidance) 3.16 semi-flexible facing system facing system with some capacity to accommodate differential settlement between fill and facing 3.17 flexible facing system pliant, articulated, facing system with capacity to accommodate differential settlement between fill and facing 3.18 green facing vegetative cover or infill used without facing units or as an adjunct to reinforced fill structures constructed using
facing units 3.19 cladding false facing added in front of the facing to improve the aesthetics of a finished reinforced fill structure 3.20 design life service life, in years, required by the design 3.21 temporary structures structures with a design life of 1 - 5 years (Class 1) 3.22 permanent structures structures with a design life of more than 5 years (Class 2 – 5)
EN 14475:2006 (E) 10 4 Information needed for construction 4.1 Prior to commencement of any construction work all information necessary for the construction of the works in compliance with the design and contract documents shall be provided. 4.2 Information shall include definition of the reporting procedure to deal with unforeseen circumstances, or with any conditions revealed or considered during construction which appear to be worse than those assumed in the design. 4.3 Information shall include definition of the reporting procedure if an observational method of design is adopted or monitoring is required. 4.4 Notice of any restrictions such as any construction phasing required by the design, any restrictions on site access, any environmental restrictions or any statutory restrictions on the site shall be provided. 4.5 For works to be constructed to specified levels, co-ordinates and tolerances these shall be shown on plans, or in the specification, together with the positions, levels of and co-ordinates of fixed reference points at or near the works construction site. 4.6 When relevant a schedule of any testing and acceptance procedures for materials incorporated in the works shall be provided. 4.7 When samples of reinforcements are to be installed for the assessment of their long term degradation, or pull-out capacity, detailed instructions with regard to their location, identification and installation shall be provided. 4.8 To avoid damage to existing or proposed services the accurate location of all services such as electricity, telephone, water, gas, drains and sewers shall be ascertained. 4.9 If the site is subject to tidal working or flooding, cold climate conditions or allied restrictions, details of such restrictions shall be ascertained. 5 Geotechnical investigations 5.1 The extent of any site investigation shall be sufficient to allow determination of ground conditions at the site in accordance with the requirements of EN 1997-1 and to enable construction of the works in compliance with the contract documents and design. 5.2 Geotechnical, hydrogeological and hydrological information should be provided to enable the constructor to design any temporary works or accesses needed for construction (e.g. earthworks, embankments, stabilization of excavations or cuttings near the structure, construction of cofferdams.) 5.3 Relevant geotechnical investigation shall be provided to determine the properties of the fill material related to:
workability, in accordance with 6.2.2; aggressiveness against the reinforcements or the facing, in accordance with 6.2.8; internal friction and cohesion, in accordance with 6.2.10. 5.4 A geotechnical investigation, in accordance with 6.2.8.1 to 6.2.8.3, shall be provided, when relevant, to determine the aggressiveness of:
foundation material which can be in contact with the reinforcement or facing;
EN 14475:2006 (E) 11 ground water which can soak the selected fill and affect its own aggressiveness. 6 Materials and products 6.1 General 6.1.1 Construction of reinforced fill involves the use of the following major components: fill material; fill reinforcement, and if required; facing system. All materials and products shall conform to the specifications of the design and with the technical requirements of the suppliers if proprietary systems are used. All materials used shall be mutually compatible. 6.1.2 The source of supply of all materials, fill, reinforcements, facing etc. shall be documented. The source of materials shall not be changed without prior notice. 6.2 Fill materials 6.2.1 General 6.2.1.1 The fill used within the reinforced zone shall be selected to meet the properties required by the design and the project specification. 6.2.1.2 The suitability of a reinforced fill material is dependent on a number of factors that shall be considered when selecting the material: fill workability; function and environment of the structure and long term behaviour; fill layer thickness and maximum particle size; facing technology; vegetation; drainage properties; aggressivity of the fill; fill – reinforcement interaction; fill – internal friction and cohesion; frost susceptibility. 6.2.2 Fill workability 6.2.2.1 The fill workability shall be such that it can be placed and compacted to produce the properties required by the design.
EN 14475:2006 (E) 12 6.2.2.2 The selection of the fill shall take into account the climatic conditions under which the fill will be placed, the compaction plant and local practice and experience. See Annex A for guidance. 6.2.2.3 Any relevant local experience in the construction of unreinforced embankments shall be considered in the fill selection for reinforced fill structures. 6.2.2.4 Any additives used to improve the workability of some fill materials, e.g. lime, cement, shall be considered with regard to construction limitations. i.e. presence of reinforcement layers within the fill, chemical durability. 6.2.2.5 The fill material shall be free from snow and ice. Frost susceptible materials shall not be placed in sub-zero conditions
6.2.3 Function and environment of the structure and long term behaviour 6.2.3.1 Some types of structure have a critical function where post construction settlement is very important. e.g. bridge abutments, walls supporting railway tracks and buildings, or high earth retaining structures etc. In these cases fill material which is easy to compact and which will have subsequent low compressibility shall be selected. (see Annex A for guidance). 6.2.3.2 Where a structure is exposed to flooding and subsequent rapid drawdown the drainage properties of the fill shall be checked for compatibility with the design assumptions. 6.2.3.3 The behaviour of some fine grained soils, shall be considered with regard to the design life, long term performance and function of the reinforced soil structure. Degradable fill materials and friable soils shall not be used unless specific studies are carried out to validate their use. In particular the properties of materials which are susceptible to break down shall be assessed from trial tests, or tests performed on the material after compaction. 6.2.4 Fill layer thickness and maximum particle size 6.2.4.1 The maximum particle size should allow an acceptably even surface to be formed and be compatible with the compacted layer thickness. The maximum particle size can also be a function of the spacing of the layers of reinforcement and, where relevant, of the size of the facing units. 6.2.4.2 The maximum particle size will also be determined by the choice of reinforcement in order to keep the construction damage within the specified design limits. See 6.2.8.4. 6.2.4.3 The compaction equipment used close to the facing of the structure is generally required to be lighter than within the body of the fill (unless specified otherwise by the soil reinforcement system). This may result in thinner compacted layers, to achieve the required fill density. 6.2.4.4 Unsuitable fills such as organic soils, soluble materials and strongly swelling materials shall not be used. 6.2.5 Facing technology 6.2.5.1 The compatibility of compaction induced settlement and post construction settlement with the facing system used shall be considered when the fill is selected. See Annex A and C for guidance. 6.2.6 Vegetation 6.2.6.1 When a vegetative cover on the facing (greened surface) is planned, the fill material placed near the front of the construction shall meet specified requirements for vegetative cover.
EN 14475:2006 (E) 13 6.2.7 Drainage properties 6.2.7.1 When using drainage geosynthetics the drainage and filtration properties of the geosynthetic shall be compatible with the selected fill. 6.2.8 Aggressivity of the fill 6.2.8.1 The electro-chemical, chemical and biological aggressivity of the fill materials shall be considered to ensure that these properties do not have a detrimental effect on the performance of the reinforcement or the facing. 6.2.8.2 The assessment of the electrochemical, chemical or biological suitability of the selected fill in regard to the reinforcements shall be based on previous relevant experience, e.g. established correlation between the soil characteristics and the long term strength losses of the reinforcements. 6.2.8.3 The mechanical aggressivity of the fill materials with regard to the reinforcement or facing shall be considered to assess compatibility with the design assumptions. 6.2.8.4 The assessment of mechanical damage of the reinforcements, or their coatings, caused by the selected backfill during construction shall be based on previous relevant experience where available, or on specific site testing where necessary. This is particularly important where crushed, angular, fill is used. 6.2.9 Fill reinforcement interaction 6.2.9.1 The interaction between the fill and the reinforcement shall be considered to assess compatibility with the design assumptions. 6.2.9.2 The assessment of the fill reinforcement interaction should be based on testing such as shear box or pull-out testing, and/or previous relevant experience where available. 6.2.10 Fill internal friction and cohesion 6.2.10.1 The compatibility of the internal friction and cohesion of the selected fill with the design assumptions shall be considered. 6.2.10.2 The assessment of the internal friction and cohesion of the fill shall be representative of the conditions in which it is used (e.g. density, moisture content, stress level). 6.2.10.3 The assessment of the frictional properties of free draining or granular fill materials (as defined in Annex A for guidance) may be based on previous relevant experience and related to the particle size distribution of the material. 6.2.11 Frost susceptibility 6.2.11.1 Where relevant, non frost susceptible material shall be used to a thickness of the frost depth from any surface exposed to sub-zero temperatures unless an insulating layer is used. 6.2.12 Guidance Some typical combinations of fill, reinforcement and facing units are considered in Annex A. The electrochemical properties of fills used with metallic reinforcement are considered in Annex B.
EN 14475:2006 (E) 14 6.3 Reinforcement products 6.3.1 General 6.3.1.1 Fill reinforcements can be made from metals, generally steel, or polymeric materials. See Annex D for some typical examples. NOTE Fibre glass and carbon fibre reinforcement has been used experimentally and natural fibres have been used in temporary structures. 6.3.1.2 Reinforcement shall only be used if its suitability, including durability, has been proven by trials, or experience, and by approved tests, carried out on the product or on a similar product of the same class of material and whose properties are known to be equivalent, to ascertain that the requisite properties of the reinforcement are likely to be available at the end of the specified design life in the design operating conditions. 6.3.1.3 All fill reinforcement products shall conform to the specification for the works as required by the design. 6.3.2 Steel fill reinforcement 6.3.2.1 Steel reinforcement (Figure D.1) may take the form of either strips, bars & rods to EN 10025-4, EN 10025-2 or EN 10080, ladders, welded wire meshes (also known as grids, or bar mats) to EN 10080 or woven wire meshes to EN 10218 and EN10223. They should generally have one end connected to a facing, at spacing prescribed by the design. Steel reinforcement may be provided with a protective coating to mitigate the effects of electro-chemical corrosion. Some typical examples of widely used steel reinforcements are considered in Annex E. 6.3.2.2 Steel strips, rods, bars, ladders or welded wire meshes may be provided with a galvanizing coating. The galvanizing shall conform to EN ISO 1461 with a local coating thickness of 70 µm. Thin strips to be galvanised in accordance with EN 10326, with a local coating thickness of 35 µm. A corrosion allowance shall be applied to the base metal appropriate to the design life. 6.3.2.3 Steel woven wire meshes may be provided with a zinc-aluminium alloy coating (Zn95Al5), minimum 30 µm thick further protected by a 0,5 mm thick PVC or PE coating. The zinc-aluminium coating shall conform to EN 10244-2. 6.3.2.4 Stainless steel or aluminium alloys should not be used for soil reinforcement in permanent structures unless for particular cases and based on specific studies. 6.3.3 Polymeric reinforcement 6.3.3.1 Polymeric reinforcement can take many forms, (Figure D.2), such as strips, grids or sheets which may not be connected to a facing. Like steel strips, polymeric strips shall be installed at predetermined vertical and horizontal spacing required by the design. In contrast, only vertical spacing shall be specified for grids or sheets installed as full width reinforcement. The most commonly used polymers are polyester and polyolefins, although other geosynthetic materials may be used. 6.3.3.2 All geosynthetic fill reinforcement shall conform to the requirements of EN 13251, as far as tests and testing procedures are relevant in regard to the particular form of the reinforcement. 6.3.3.3 As required by the design, polymeric fill reinforcement in the form of strips, grids or sheets shall be provided with certified values of design strengths pertaining to the specified design life and operating temperature of the reinforced fill structure and, based on tensile creep rupture and isochronous load-strain characteristics per EN ISO 13431. 6.3.3.4 Unless they are based on previous relevant experience and/or specific testing as per clauses 6.2.8.2, 6.2.8.4 or 6.2.9.2, the certified values of the design strengths of polymeric fill reinforcement shall be
EN 14475:2006 (E) 15 based on construction induced damage as ENV ISO 10722-1, fill reinforcement interaction as EN ISO 12957-1, and durability as EN 13251, Annex B, including a consideration of resistance to weathering per EN 12224 and possibly of microbiological attack per EN 12225 6.4 Facings 6.4.1 General 6.4.1.1 Facings can be produced in a variety of materials and configurations with a variety of facing-reinforcement connections and a variety of joint fillers and bearing devices.
6.4.1.2 All facings systems and facing units, including connections between facings and reinforcement and jointing materials, when these a
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