Foreword

This European Standard 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of an identical text or by endorsement, at the latest by August 1999, and conflicting national standards shall be withdrawn at the latest by August 1999.

The remit of TC 288 is the standardisation of the execution procedures for geotechnical works (including testing and control methods) and of the required material properties. WG 3 has been charged with the subject area of bored piles, including barrettes but not "mini piles" of diameter less than 0,3 m.

For bored piles not included in this European Standard, the construction should follow, as far as applicable, the general principles of this EN 1536.

The document has been prepared to stand along side with ENV 1997-1: Eurocode 7: Geotechnical design - Part 1: General rules. Clause 7 "Design related considerations" of this European Standard expands on design only where necessary (e.g. the detailing of reinforcement) but provides full coverage of the construction and supervision requirements.

It has been drafted by a working group comprising delegates from 11 countries and against a background of more than 30 pre-existing piling standards and codes of practice both national and international. In view of different construction methods used internationally and the respective experience it can be necessary to supplement this European Standard or parts of it by a National Foreword to cater for specific or local situations.

In accordance with the CEN/CENELEC Internal Regulations, the following countries are to bound to implement this European Standard: Austria, Belgium, Czechovakia, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

1 Scope

1.1 This European Standard establishes general principles for the construction of piles

• which are formed in the ground by excavation and
• which contain a structural member to transfer loads and or limit deformations.

1.2 This European Standard covers

• piles with circular shape (see figure 1) and
• piles with barrette shape, provided the section is concreted in a single operation.

D: Pile diameter

L: Barrette length

W: Barrette thickness

A: Cross-sectional area of the shaft

1.3 The barrette shapes covered are rectangular, T- or L shaped in plan or any other similar configuration (see figure 2).

1.4 This European Standard covers piles with:

• uniform cross-section (straight shaft);
• telescopically changing shaft dimensions;
• excavated base enlargements; or
• excavated shaft enlargements

(see figure 3).

NOTE: The shape of the pile base and of an enlargement can depend on the tool used for the excavation.

1.5 The provisions of this European Standard apply to piles with the following dimensions:

• — shaft diameter: 0,3 ≤ D ≤ 3,0 m (see figure 1 and figure 3);
• — dimension for cast-in-place barrette piles:
  • W_i ≥ 0,4 mg (see fiure 2);
• — ratio between the dimensions: L_i/W_i ≤ 6
  • where:
  • L_i is the largest dimension of a cast-in-place barrette pile and
  • W_i is the least dimension of a cast-in-place barrette pile (see figure 2);
• — least dimension ≥ 0,3 m for precast elements used in barrette piles or piles:
  • D_P ≥ 0,3 m and
  • W_P ≥ 0,3 m respectively
  • where:
  • D_P is the diameter of a circular precast element;
  • W_P is the thickness of a rectangular precast element;
• — rake generally: n ≥ 4 (Θ ≥ 76°) (see figure 4);
• — rake for permanently cased piles: n ≥ 3 (Θ ≥ 72°);
• — base enlargements or cross-sectional area of barrette piles: A ≤ 10 m²;

1.6 Shaft or base enlargements covered by this European Standard are:

• — base enlargements in non-cohesive ground:
  • D_B/D ≤ 2 and
  • in cohesive ground: D_B/D ≤ 3;
• — shaft enlargements in any ground: D_E/D ≤ 2;
• — slope of the enlargement in non-cohesive ground:
  • m ≥ 3 and
  • in cohesive ground: m ≥ 1,5
  • (see figure 3)

1.7 The provisions of this European Standard apply to:

• single piles;
• pile groups (see figure 5);
• walls formed by piles (see figure 6).

D: Shaft diameter

a: Distance of the piles according to design

	Secant bored pile wall: a < D p: primary piles s: secondary piles
	Contiguous bored pile wall: a ≈ D
	Widely spaced bored pile wall: a > D a: Distance of the piles 1: Lagging

Use of plain concrete	Use of concrete with bar reinforcement	Use of special reinforcement (steel section or tube)

Use of precast concrete element as main or supplementary structural member	Use of steel tube as main or supplementary structural member

• 1: Precast concrete element
• 2: Grout
• 3: Temporary casing (extracted)
• 4: Uncased excavation
• 5: Unreinforced or reinforced concrete or cement grout
• D: Shaft diameter

1.8 The piles which are the subject of this European Standard can be excavated by continuous or discontinuous methods using support methods for stabilizing the excavation walls where required.

1.9 This European Standard applies only to construction methods that allow the designed cross-sections to be produce.

1.10 The provisions apply to piles where the bearing member is constructed

• of unreinforced (plain) concrete,
• of reinforced concrete,
• of concrete reinforced by means of special reinforcement such as steel tubes, steel sections or steel fibres,
• of precast concrete (including prestressed concrete) elements or steel tubes where the annular gap between the element or tube and the ground is filled by concrete, cement or cement-bentonite grout

(see figure 7).

1.11 Micropiles, mixed-in-place columns, columns constructed by jet grouting, ground improvement for piling, mixed-in-place pile bases and diaphragm walls are not covered by this European Standard.

2 Normative references

NOTE 1: This European Standard incorporates by undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies.

NOTE 2: Exceptionally, the list of normative references contains also European Standards and Prestandards which are at the draft stage. If one of those documents has become a European Standard, the references shall be checked.

2.1 Users of this European Standard shall satisfy themselves that the standards and other references used are current issues and that there is compatibility between the reference documents employed.

2.2 List of documents to which normative reference is made in the text:

ENV 197-1	1992	Cement - Composition, specifications and conformity criteria - Part 1: Common cements
ENV 206	1990	Concrete - Performance, production, placing and compliance criteria
EN 791	1996	Drill rigs - safety
prEN 1008	1997	Mixing water for concrete - Specification for sampling, testing and assessing the suitability of water, including wash water from receycling installations in the concrete industry as mixing water for concrete
EN 1538	1998	Execution of special geotechnical works - Diaphragm walls
ENV 1991-1	1994	Eurocode 1: Basis of design and actions on structures - Part 1: Basis of design
ENV 1992-1-1	1991	Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules for buildings
ENV 1994-1-1	1992	Eurocode 4: Design of composite steel and concrete structures - Part 1-1: General rules for buildings
ENV 1997-1	1994	Eurocode 7 Geotechnical design - Part 1: General rules
EN 10025	1990	Hot rolled products of non-alloy structural steels - Technical delivery conditions
ENV 10080	1995	Steel for reinforcement of concrete, weldable ribbed reinforcing steel В 500 - Technical delivery conditions for bars, coils and welded fabric
EN 10210-1	1994	Hot finished structural hollow sections of non-alloy and fine grain structural steels - Part 1: Technical delivery requirements
prEN 12620	1996	Aggregates for concrete including those for use in roads and pavements

3 Definitions

NOTE: The following definitions are used for the construction of bored piles covered by this European Standard. Additional explanations of piling terms are listed in Annex A. For the purposes of this European Standard, the following definitions apply.

3.1 pile

fr: pieu

de: Pfahl

Slender structural member in the ground for the transfer of actions. For the purpose of this European Standard the slenderness ratio is not limited.

3.2 bored pile

fr: pieu fore

de: Bohrpfahl

Pile formed with or without a pile casing by excavating or boring a hole in the ground and filling with plain or reinforced concrete.

3.3 barrette

fr: barrette

de: Schlitzwandelement

Discrete length of diaphragm wall, usually short, or a number of interconnecting lengths cast simultaneously (e.g. L-, T- or cruciform shapes), used to support vertical and/or lateral loads.

3.4 compression pile

fr: pieu EN compression

de: Druckpfahl

Pile to resist compressive forces.

3.5 continuous flight auger pile (CFA-pile)

fr: pieu à la tarière continuecreuse (CFA)

de: Schneckenbohrpfahl

Bored pile formed by means of a hollow stemmed continuous flight auger through the stem of which concrete or grout is pumped as the auger is extracted (see figure A.9).

3.6 end bearing pile

fr: pieu travaillant EN pointe

de: Spitzendruckpfahl

Pile transmitting forces to the ground mainly by compression on ist base.

3.7 enlarged base

fr: base élargie

de: Fuβaufweitung

Base of a pile formed to have an area greater than that of ist shaft. For bored piles, normally constructed by the use of special underreaming or belling-out tools (see figure 3).

3.8 friction pile

fr: pieu flottant

de: Reibungspfahl

Pile transmitting actions to the ground mainly by friction and adhesion between the lateral surface of the pile and the adjacent ground.

3.9 prepacked pile

fr: pieu ballasté injecté

de: Prepacked-Pfahl

Pile where the completed excavation is filled with coarse aggregate which is subsequently injected with cement mortar from the bottom up.

3.10 shaft diameter

fr: diamètre du fût

de: Pfahldurchmesser

Diameter of the part of the pile between the pile head and the pile base:

• a) for bored piles constructed with casings: equal to external diameter of the casing;
• b) for bored piles constructed without a casing: equal to the maximum diameter of the boring tool.

3.11 tension pile

fr: pieu EN traction

de: Zugpfahl

Pile designed to resist tensile forces.

3.12 preliminary pile

fr: pieu préliminaire

de: Probepfahl (1)

Pile installed before the commencement of the main piling works or section of the works for the purpose of establishing the suitability of the chosen type of pile and/or for confirming the design, dimensions and bearing capacity.

3.13 trial pile

fr: pieu de faisabilité

de: Probepfahl (2)

Pile installed to assess the practicability and suitability of the construction method for a particular application.

3.14 test pile

fr: pieu d'essai

de: Probepfahl (3)

Pile to which loads are applied to determine the resistance deformation characteristics of the pile and the surrounding ground.

3.15 working pile

fr: pieu de fondation

de: Bauwerkspfahl

Pile for the foundation of a structure.

3.16 static pile test

fr: essai de chargement statiquede pieu

de: statische Probebelastung

Loading test where a pile is subjected to chosen axial and/or lateral forces at the pile head for the analysis of its capacity.

3.17 maintained load pile test

fr: essai de chargement par palier

de: lastgesteuerte Probebelastung

Static loading test in which a test pile has loads applied in incremental stages, each of which is held constant for a certain period or until pile motion has virtually ceased or has reached a prescribed limit (ML-test).

3.18 constant rate of penetration test

fr: essai de chargement à vitessed'enfoncement constante

de: weggesteuerte Probebelastung

Static loading test in which a test pile is forced into the ground at a constant rate and the force is measured (CRP-test).

3.19 dynamic pile test

fr: essai de chargementdynamique de pieu

de: dynamischer Pfahlversuch

Loading test where a dynamic force is applied at the pile head for assessment of pile capacity.

3.20 integrity test

fr: essai d'intégrité

de: Integritätsprüfung

Test carried out on an installed pile for the verification of soundness of materials and of the pile geometry.

3.21 sonic test

fr: essai d'auscultation soniquepar réflexion

de: Ultraschallversuch

Integrity test of a pile where a series of sonic waves is passed between a transmitter and a receiver through the concrete of a pile and where the characteristics of the received waves are measured and used to infer continuity and section variations of the pile shaft.

3.22 sonic coring

fr: essai d'auscultation soniquepar transparence

de: Ultraschallversuch im Pfahl

Sonic integrity test of pile concrete carried out from core drillings in a pile shaft or from a pre-placed tube system.