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of an identical text or by endorsement, at the latest by August 1999, and conflicting national standards shall be withdrawn at the latest by August 1999.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:
- Wi ≥ 0,4 mg (see fiure 2);
- — ratio between the dimensions: Li/Wi ≤ 6
- where:
- Li is the largest dimension of a cast-in-place barrette pile and
- Wi 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:
- DP ≥ 0,3 m and
- WP ≥ 0,3 m respectively
- where:
- DP is the diameter of a circular precast element;
- WP 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:
- DB/D ≤ 2 and
- in cohesive ground: DB/D ≤ 3;
- — shaft enlargements in any ground: DE/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.
