EN 12699:2000 Execution of special geotechnical work – Displacement piles
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of an identical text or by endorsement, at the latest by June 2001, and conflicting national standards shall be withdrawn at the latest by June 2001.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
This Standard has been prepared by the Working Group (WG 5) of the Technical committee of the Execution of Special Geotechnical Works (TC 288) of the European Committee for Standardisation (CEN). The general 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 5 has been working with the subject area of displacement piles.
The document has been prepared to stand alongside ENV 1997 Eurocode 7 Part 1: Geotechnical Design, General Rules. Clause 7 of this Standard covers design aspects of piles.
This document has been drafted by a working group comprised of experts from 14 countries and is based on review of 12 national and international codes of practice.
The annexes A und B are informative.
1.1 This standard establishes general principles for the execution of displacement piles, that means piles which are installed in the ground without excavation or removal of material from the ground except for limiting heave, vibration, removal of obstructions or to assist penetration.
Piles are driven into the ground using impact, vibration, pressing, screwing or a combination of these methods.
1.2 The material of displacement piles covered by this standard can be:
- cast iron;
- concrete, mortar;
- combination of above.
1.3 This standard covers prefabricated, cast in place, or a combination of these methods to form displacement piles of regular shape.
Examples are given in Figures A.2 and A.3 in annex A.
1.4 This standard is limited to piles with a diameter or maximum cross sectional dimension greater than 150 mm.
1.5 Other than practical considerations there are for the purpose of this Standard no limitations regarding shaft or base enlargements, length or rake.
1.6 The provisions of the standard apply to:
- single piles;
- pile groups;
- walls formed by concrete sheet piles.
1.7 Columns constructed by ground improvement techniques (such as mixed in place columns, jet grouting, compaction grouting, vibro flotation, stone columns are not covered by this standard. Bored piles are covered in EN 1536. Steel and timber sheet pile
s walls are covered in EN 12063. Micropiles are covered in (WI 00288010)1).
1) A standard on micropiles is under preparation.
2 Normative references
This European Standard incorporates by dated or 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 (including amendments).
EN 288-2, Specifications and approval of welding procedures for metalic materials – Part 2: Welding procedures specifications for arc welding.
EN 499, Welding consumables – Covered electrodes for manual metal arc welding of non alloy and fine grain steels – Classification.
EN 791, Drill rigs – Safety.
EN 996, Piling Equipment – Safety Requirements.
EN 1536, Execution of special geotechnical works – Bored piles.
EN 10248, Hot rolled sheet piling of non alloy steels.
EN 25817, Arc welded joints in steel – guidance on quality levels for imperfections (ISO 5817:1992).
EN 29692, Metal-arc welding with covered electrode, gas-shielded metal-arc welding and gas welding – Joint preparations for steel.
ENV 206, Concrete – Performance, production, placing and compliance criteria.
ENV 1991-1, Eurocode 1- Basis of design and actions on structures – Part 1: Basis of design.
ENV 1992-3, Eurocode 2: Design of concrete structures – Part 3: Concrete foundations.
ENV 1993-5, Eurocode 3: Design of steel structures – Part 5: Piling.
ENV 1994-1-1, Eurocode 4: Design of composite steel and concrete structures – Part 1-1: General rules and rules for buildings.
ENV 1995-1-1, Eurocode 5 – Design of timber structures – Part 1.1: General rules and rules for buildings.
ENV 1997-1: 1994, Eurocode 7: Geotechnical design – Part 1: General rules.
EN ISO 4063, Welding and allied processes – Nomenclature of processes and reference numbers (ISO 4063:1998).
prEN 12063, Execution of special geotechnical work – Sheet pile walls. prEN 12794:1997, Precast concrete foundation piles.
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply:
pile which is installed in the ground without excavation or removal of material from the ground except for limiting heave, vibration, removal of obstructions or to assist penetration
prefabricated (displacement) pile
pile or pile element which is manufactured in a single unit or in pile segments before installation
cast in place (displacement) pile
pile installed by driving a closed ended concrete shell or permanent or temporary casing, and filling the hole so formed with plain or reinforced concrete
pile made up of two or more types or sizes of piles joined together. The connection between the components is designed to transmit load and to prevent separation during and after construction. (= composite pile) See Figure A.8 of annex A
pile in which the pile or pile tube comprises a limited number of helices at its base and which is installed under the combined action of a torque and a vertical thrust. By the screwing-in and/or by the screwing-out, the ground is essentially laterally displaced and virtually no soil is removed. See Figure A.10 of annex A
pile pressed into soil by means of static force
prefabricated pile fitted with an enlarged shoe to create along a part or the full perimeter of the pile a space which is filled during driving with grout, mortar or microconcrete. See Figure A.11 of annex A
post grouted pile
pile where shaft and/or base grouting is performed after installation through pipes fixed along or incorporated in the pile. See Figure A.12 of annex A
steel tube used temporarily or permanently to support shaft walls during the construction of a pile. In permanent situation the casing can act as a protective or load bearing unit
steel tube used to displace the ground during the formation of a driven cast in place pile. Drive tube is withdrawn during concreting
a tube, generally of thin steel plate, forming part of the shaft of a pile, e.g. used for the protection of pile shafts in soft or aggressive grounds or to reduce negative skin friction
means of joining lengths of pile elements either by welding or by mechanical joints (examples see Figures A.7, A.8 and A.9 of annex A)
shoe or point fitted to the base of a pile or drive tube to form the toe (examples see Figures A.4a to A.4h and A.13 of annex A)
shaft enlargements to steel piles formed by welding steel sections to the pile. (see example in Figure A.2j of annex A)
steel sections used for guiding driving equipment and/or pile during driving. See Figure A.6 of annex A
tool of construction equipment for driving piles by impact (striking or falling mass)
vibrator (vibrating hammer)
tool of construction equipment for driving or extracting piles, drive tubes or casing by the application of vibratory forces
device, usually steel, placed between the base of the impact hammer and the pile or drive tube so as to uniformly distribute the hammer impact to the top of the pile. See Figure A.6 of annex A
device or material placed between the impact hammer and the helmet to protect the hammer and the pile head from destructive direct impact. The hammer cushion material shall have enough stiffness to transmit hammer energy efficiently into the pile. See Figure A.6 of annex A
material, usually softwood, placed between the helmet and the top of a precast concrete pile. See Figure A.6 of annex A
a temporary extension, used during driving, that permits the driving of the pile top below ground surface, water surface, or below the lowest point to which the driving equipment can reach without disengagement from the leaders
a steel core for driving that is inserted into a closed-end tubular pile. After installation the mandrel is withdrawn
method to bring the piles into the ground to the required depth, such as hammering, vibrating, pressing, screwing or by a combination of these or other methods
pile which is forced into the soil by driving, the soil being displaced by the pile or drive tube
method used to assist a pile to penetrate the ground e.g. jetting, preboring, preblasting, predriving
removal of soil by core sampler (e.g. to mitigate the effects of heave by pile driving)
use of pressurised water to facilitate the driving of a pile by means of hydraulic displacement of parts of the soil
preboring (preaugering, predrilling)
boring through obstructions or materials too dense to penetrate with the planned pile type and driving equipment
injection of a fluid cementitious mixture (e.g. cement grout, mortar, micro concrete)
a single hammer blow to a prefabricated pile that is monitored for energy input and measurement of pile strain/acceleration and/or pile set are made, to allow assessment of pile bearing resistance
an additional series of hammer blows used to drive the prefabricated pile to re-establish the required driving resistance
method used to form an enlarged shaft on a temporarily cased driven cast in place pile
first working pile on construction site
pile to which a load is applied to determine the resistance deformation characteristics of the pile and surrounding ground
pile installed to assess the practicability and suitability of the construction method for a particular application
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, driving equipment and/or for confirming the design, dimensions and bearing capacity
driving parameters used to be fullfilled when driving a pile
mean permanent penetration of a pile in the ground per blow measured by a series of blows
the passive role of checking the technical quality of the piling process
the active role of overseeing or directing the piling operations
to make a permanent record of the facts relating to the piling operations and aspects monitored
maintained load pile test
static loading test in which a testpile 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)
constant rate of penetration pile load test
static loading test in which a test pile is forced into the ground at a constant rate and the force is measured (CRP – test)
dynamic pile load test
loading test where a pile is subjected at the pile head to a dynamic force for analysis of its load bearing capacity
sonic test, low strain integrity test
integrity test where a series of 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
sonic integrity test of pile concrete carried out from core drillings in a pile shaft or from a pre-placed tube system
level of the piling platform on which the piling rig works. See Figure A.13 of annex A
final level to which the concrete is cast. It is above the cut off level by a margin depending on the execution procedure. See Figure A.13 of annex A
cut off level
prescribed level to which a pile is cut or trimmed back to before connecting it to the superstructure. See Figure A.13 of annex A
lowest level of pile. See Figure A.13 of annex A
upper area of pile. See Figure A.13 of annex A
upper part of pile. See Figure A.13 of annex A
the body of the pile between the head and the base. See Figure A.13 of annex A
lower part of a pile. See Figure A.13 of annex A
bottom area of pile. See Figure A.13 of annex A
a means of protecting steel piles from corrosion by providing a consumable anode or by applying an external electrical potential
direct current that is induced in the soil which can cause corrosion of a pile
stage after mixing concrete when it turns from liquid to solid
prefabricated section originally manufactured for other purposes but accepted as suitable for use as a pile e.g. steel pipe for oil
upward movement of ground or pile
separation of fibres at the toe or head of a timber pile
NOTE In EN 1536 annex A there is an explanation of common piling terms.
4 Information needed
4.1 Any information relevant to the execution of the works on site shall be provided with the specification for the works.
4.2 The following minimum information should be considered and made available before commencement on site:
a) ground investigation report(s) at the construction site, as well as additional information of the subsoil at the building site, such as the presence of:
- structure and foundation remnants;
- artificial elements (utility lines and services);
- underground contamination or hazards;
- presence of fill material;
b) specifications on design and execution of the piling works and additional requirements for the supervision, monitoring or testing of the works;
c) present topographic data, such as:
- slope, actual ground level;
- location of main grid lines and site datum level;
- piling platform level(s) related to site datum;
d) site conditions and limitations which can affect the piling work, such as:
- size of working area, topography, slope, access roads, access limitations for equipment and materials, head-room restrictions;
- concurrent activities, e.g. dewatering, tunnelling, deep excavations;
- presence of trees, overhead cables / power lines;
- proximity of potential unstable slopes;
e) environmental conditions and limitations which can affect the piling work, in relation with:
- presence and condition of sensitive buildings or installations in the vicinity of the piling works;
- environmental restrictions e.g. on noise, vibration or pollution;
- any legal or statutory restrictions e.g. time restrictions;
f) other aspects such as:
- possible corrosion and abrasion problems;
- previous experience with displacement piles or other foundation methods on or adjacent to the site;
- foundations of adjacent buildings.
4.3 Any additional or deviating requirements falling within the permission clauses given in this standard shall be established and agreed before the commencement of the works and the quality control system shall be suitably amended, e.g. for:
- reduced or increased geometrical construction deviations;
- application of different alternative construction materials;
- special reinforcement, e.g. the use of steel tube or steel sections or fibres (steel or manmade);
- grouting of pile shafts or bases;
- use of rock shoes;
- use of driving assistance (preboring, waterjetting,...);
- use of friction reducing coatings.
5 Site investigation
5.1 The general requirements for the ground investigation are contained in ENV 1997-1:1994.
5.2 The ground investigation shall be sufficiently extended to recognise the presence of all ground formations and layers affecting the construction and performance of the piles, and to determine their characteristic strength and deformation properties required for the design.
5.3 The following information, when relevant for the execution of displacement piles should be given in the ground investigation report(s):
- a) ground level at any point of investigation or testing relative to the recognised national datum or an agreed reference point;
- b) presence and characteristics of loose or soft soils or ground that is likely to soften, loosen or become unstable during the execution of displacement piles;
- c) presence of cobbles and boulders or other natural or artificial underground obstructions that can cause difficulties for the installation or could require special methods or tools for their penetration or removal;
- d) the thickness, level and characteristics of soft strata below the bearing stratum that could affect the pile foundation performance;
- e) presence, extent and thickness of any strata that can be sensitive to water infiltration or to stresses caused by piling tools (e.g. impact or vibration);
- f) piezometric levels of groundwater and its variation, including any artesian groundwater tables and water wells;
- g) any strata where high ground water velocities exist;
- h) aggressiveness of groundwater or ground that could affect the durability and setting of the pile material;
- i) level and inclination of any relevant underlying rock / surface;
- j) thickness and extent of any existing weathered rock;
- k) presence, extent and thickness of contaminated soil or waste, that can influence the pile quality and the handling and disposal of any excavated material or lead to contamination of underlying strata.
6 Materials and products
6.1.1 All material and products for incorporation into the displacement pile shall be in accordance with the relevant European Standard(s), technical requirements and/or with the specification for the works.
6.1.2 The sources of supply of materials:
- shall be documented; and
- shall not be changed without prior notification.
6.1.3 The dimensional tolerances shall comply with relevant European Standards.
6.1.4 Where a pile shoe is used it shall comply with the relevant material standard or specification.
6.2 Prefabricated displacement piles
6.2.1 Concrete piles
184.108.40.206 The materials and fabrication of prefabricated concrete piles, including joints, shall comply prEN 12794:1997.
6.2.2 Steel Piles
220.127.116.11 The materials, and fabrication of steel piles shall as a minimum comply with ENV 1993-5.
18.104.22.168 Re-used and second choice steel piles shall as a minimum comply with the requirements concerning type, size, tolerances, quality and steel grade specified in the design and be free from damage and corrosion that would affect strength and durability.
22.214.171.124 Concrete which is subsequently cast in a steel pile shall comply with ENV 206.
6.2.3 Timber piles
126.96.36.199 The materials, fabrication and handling of timber piles shall comply with ENV 1995-1-1 unless specified otherwise in the following paragraphs.
188.8.131.52 Hewn piles shall be evenly tapered. The section dimensions should not change more than 0,015 m/m. The straightness of the pile shall not deviate from the straight line more than 1 % of the length.
184.108.40.206 Piles shall be provided in one piece unless otherwise approved.
220.127.116.11 Preservation methods shall comply with the specification.
6.2.4 Cast Iron piles
18.104.22.168 Cast iron piles shall comply with the specification of the manufacturer and the design.
6.3 Cast in place displacement piles
6.3.1 All material and products incorporated into the pile shall be in accordance with EN 1536 unless specified otherwise.
6.3.2 Semi dry concrete may be used if tamped during installation. The cement content for semi dry concrete shall be of at least 350 kg/m3. The strength class shall be at least C25/30 and workability as specified.
6.4.1 Grout shall comply with EN 1536.
6.5 Paints, coatings and other shaft protections
6.5.1 Coatings used to reduce shaft friction shall comply with the specification.
6.5.2 Paints, coatings and other means of corrosion protection, or preservation products for piles, shall comply with the specifications in the design and be applied in accordance with the manufacturers instruction.
7 Design related considerations
7.1.1 The basic standards for the design of displacement piles are:
- basis of design and actions on structures: ENV 1991-1;
- structural design of concrete piles: ENV 1992-3;
- structural design of steel piles: ENV 1993-5;
- structural design of composite piles: ENV 1994-1-1;
- structural design of timber piles: ENV 1995-1-1;
- bearing resistance: ENV 1997-1.
7.1.2 This present Standard gives design rules related to execution which are not covered by the above standards and which can influence the design or the detailing of displacement piles.
7.2.1 The design of displacement piles shall establish the type and size of pile and that its installation is appropriate for the particular ground conditions and environmental constrains.
NOTE This can often be established on the basis of previous comparable experience.
7.2.2 If no comparable experience exists regarding the driveability, one or more driving tests should be carried out at chosen locations before the main work commences.
NOTE A driving test offers the possibility of investigating driving procedures, equipment, techniques to assist driving and to assess the effect of pile construction on soil behaviour and the environment. In addition driving tests can be used to establish installation criteria and give an indication of the pile length and bearing capacity.
Driveability analysis can help to define suitable driving procedures, driving equipment and driving stresses.
7.2.3 When the driveability of the piles is investigated, account shall be taken of any requirements in the design or specification regarding techniques to assist driving (e.g. jetting, pre-boring, chiselling, blasting).
7.3 Geometrical construction deviations
7.3.1 Unless specified otherwise, piles shall be installed within the following geometrical deviations:
- plan location of vertical and raking piles (measured at the working levels):
- on land: e ≤ 0,1m
- over water: in accordance with the specifications,
- inclination of vertical piles:
- i ≤ imax = 0,04 (0,04 m/m)
- inclination of raking piles:
- i ≤ imax = 0,04 (0,04 m/m)
i is the tangent to the angle between the designed and as built centre line of the pile.
7.3.2 Geometrical construction deviations shall be taken into account in the design. If the specified deviations are exceeded, the extent of a possible overloading of any structural part shall be investigated and suitable remedial measures taken if necessary.
7.3.3 Where geometrical deviations other than those stated above are required or allowed they shall be agreed before the commencement of the work.
NOTE This might be the case in regard to constructional demands (small diameter piles, walls), ground conditions, available piling equipment or low cut-off level.
7.3.4 For the recording of construction deviations the centre of a cast in place pile is considered as the centre of gravity of the longitudinal reinforcement or, for unreinforced piles the centre of the largest circle which can be drawn within the section of the pile head.
7.3.5 An acceptable limit of vertical and lateral pile displacement should be established.
7.4 Sequence of installation
7.4.1 The sequence of driving piles shall be planned.
7.4.2 This sequence should take account of:
- the detrimental effects of any lateral or vertical movement of a pile or a group of piles is minimised;
- the bearing resistance of previously installed piles is not detrimentally reduced related to the design load;
- the soil surrounding the pile is not compacted to the extent that other piles cannot be installed properly;
- the vibrations caused by driving cast in place piles do not affect adjacent fresh concreted piles or concrete which has taken initial set.
7.4.3 For piles which have displaced detrimentally, the overall pile performance shall be reassessed.
7.4.4 Local or comparable experience can influence the proposed sequence of installation.
7.5 Protection of piles
7.5.1 Piles shall be protected against attack by organisms, aggressive substances, corrosion and stray current where such risks exist.
The measure to be taken shall be considered and specified in the design.
7.5.2 Possible measures include:
- the use of an adequate chemical steel composition;
- the use of an adequate concrete or mortar composition;
- cathodic protection;
- organic or inorganic coatings or treatment;
- concrete coating;
- use extra material thickness;
- use of permanent casings or liners.
7.5.3 Piles shall not be surface treated in such a way that the shaft resistance is reduced unless allowed or required by the design.
NOTE Negative friction can be reduced by the application of a suitable coating.
7.5.4 Timber piles for permanent structures shall only be used below the lowest anticipated ground water table or free water level during the life time of the structure unless adequate protection is provided.
7.5.5 For cast in place piles where the soil has a characteristic undrained shear strength less than 15 kPa a permanent casing or liner or other approved stabilising measures should be installed unless relevant experience has proven that it is not necessary.
7.5.6 The method of installing the liner shall be agreed.
7.6 Needs for driving assistance
7.6.1 The influence of driving assistance methods on the performance of the piles and safety of existing structures or potentially unstable slopes shall be considered in the design.
7.6.2 Any driving assistance such as predriving, preboring, water jetting, chiselling or preblasting shall be planned and be approved prior to start of work.
7.6.3 Driving aids should be carried out in such a manner that the bearing capacity of piles already in place or the safety of existing structures is not detrimentally affected.
7.7 Design for impact driving of prefabricated elements
22.214.171.124 Installation procedures, pile driving hammers, pile and hammer cushioning, pile size and length, and other factors affecting the driving stresses imparted to the pile shaft should be evaluated and taken into account when determining the driving criteria.
126.96.36.199 If there is the risk of overstressing the pile shaft a wave equation analysis should be carried out.
188.8.131.52 This analysis can be supplemented by stress wave measurements on site.
184.108.40.206 Driving stresses calculated, deduced or determined as outlined above in 7.7.1 should not exceed, at any point along the pile shaft, the values shown below in 7.7.2, 7.7. 3 and 7.7.4.
7.7.2 Prefabricated concrete piles
220.127.116.11 The transferred energy of the driving system should be chosen so that:
- in compression:
- the maximum calculated stress (including the prestress) during driving does not exceed 0,8 x characteristic concrete strength in compression at the time of driving;
- in tension:
- the calculated force should not exceed 0,9 × f × A minus prestress force, where:
- f: the characteristic yield stress of the reinforcement;
- A: area of the reinforcement.
18.104.22.168 Where stresses are actually monitored during impact driving, these may be 10 % higher than the values stated in 22.214.171.124.
126.96.36.199 When assessing the driving stresses, attention should be paid when driving from a hard layer into a soft layer as high tensile stresses may occur in the pile.
7.7.3 Steel piles
188.8.131.52 The transferred energy of the driving system should be chosen so that the maximum calculated stress in steel piles during driving should not exceed 0,9 x the characteristic yield strength of the steel.
184.108.40.206 Where stresses are actually monitored during impact driving, these may be 20 % higher than the values stated in 220.127.116.11.
7.7.4 Timber piles
18.104.22.168 The transferred energy of the driving system should be chosen so that the maximum compressive stress generated during driving should not exceed 0,8 times the characteristic compressive strength measured parallel to grain of the timber.
22.214.171.124 Where stresses are actually monitored during impact driving, these may be 10 % higher than the values stated in 126.96.36.199
188.8.131.52 Allowance should be made for reduction in section caused by drilling and notching details.
7.8 Specific design related considerations
184.108.40.206 Where the following matters are of importance to the quality or performance of the displacement piles they should be specified in an early stage of the design, prior to or during the execution stage. Items include:
- method of joining;
- quality of the weld for splices;
- method, minimum length and tolerances of cutting back pile elements;
- shape and structure of shoe or other precautions if necessary to protect and secure the toe of the pile in the bedrock;
- effects of time on pile capacity;
- restrike testing of prefabricated piles;
- adjustment of the driving criteria when a follower is used.
7.8.2 Reinforcement of cast in place piles
220.127.116.11 The reinforcement cage for cast in place piles shall be designed not only to have adequate strength in the final pile, but also adequate strength and stiffness during handling of the cage and construction of the pile. It shall also allow the fresh concrete to flow easily around each of its components.
18.104.22.168 Starter bars or dowel bars installed into fresh or hardened concrete for connection to a superstructure shall be in accordance to ENV 1992-3.
22.214.171.124 Where steel tubes or sections are used for the reinforcement of piles their design shall be in accordance with ENV 1994-1-1.
126.96.36.199 Unless otherwise agreed in the design, cast in place concrete piles shall be reinforced over their full length.
188.8.131.52 A cast in place displacement pile may be designed as an unreinforced concrete element if:
- actions caused by the construction; and/or
- actions resulting from the ground;
- actions resulting from the ground produce only compressive stresses in the pile; and
- the pile is not located in a seismic area.
184.108.40.206 In order to cater for accidental loads (e.g. resulting from construction works on the site, pile eccentricity, ...) the minimum reinforcement as given in 220.127.116.11 shall however be used over the top upper 4 m for bearing piles.
18.104.22.168 Piles should also be reinforced over any length through soft or loose soil unless otherwise specified.
22.214.171.124 Tension piles shall in any case be reinforced over their whole length.
126.96.36.199 Where reinforcement is required and unless otherwise proven by design the minimum amount of longitudinal reinforcement shall be:
- 0,5 % of the pile nominal cross section;
- minimum four bars of 12 mm nominal diameter.
188.8.131.52 The clear distance between the longitudinal reinforcement cage bars shall be at minimum:
- 100 mm;
- 80 mm when using d ≤ 20 mm aggregate.
The spacing may be reduced along the lap length of the bars.
184.108.40.206 The transversal reinforcement shall fulfil the following values:
- minimum diameter of the bars: 5 mm;
- minimum distance between the bars: as for the longitudinal bars.
220.127.116.11 The cover to all reinforcement in cast in place piles shall be not less than:
- 50 mm for piles with temporary casing;
- 75 mm in case of exposure class 5 following ENV 206 or when reinforcement is installed subsequent to concrete placement;
- 40 mm to the internal face of a permanent casing or lining.
7.8.3 Pile shoe
18.104.22.168 Pile shoe of displacement piles shall be manufactured from durable material capable of withstanding the stresses caused by the installation method and ground conditions without damage.
22.214.171.124 The pile shoe for cast in place piles shall be designed to prevent water from entering into the drive tube during construction.
126.96.36.199 The pile toe of prefabricated concrete and steel displacement piles should be designed when driving into hard rock, onto a sloping rock surface, suspected hard rock or when driving in soil with hard boulders.
NOTE In weak rock or soils the pile toe can be protected with other methods e.g. bands, extra reinforcement, plates.
Typical examples of pile and rock shoes are shown in Figure A.4 of annex A.
188.8.131.52 When driving timber piles:
- In soft soils no toe protection is normally required.
- In other soils the toe should have protection unless comparable experience shows otherwise.
7.8.4 Pile joint
The joints of prefabricated displacement piles and combined displacement piles shall be capable of maintaining the alignment and position of the pile elements during installation. They shall also safely resist the stresses from handling, driving and actions from the structure and surrounding soil.
Typical examples of pile joints are shown in Figures A.7, A.8 and A.9 of annex A.
7.8.5 Pile enlargement
184.108.40.206 Where pile enlargements are considered, the method of forming the enlargement and the bearing area and shaft parameters to be used in the design shall be agreed.
Examples of enlargements are shown in Figure A.2 of annex A.
220.127.116.11 When redrives are used to form enlarged bases or enlarged shafts on cast in place piles the method used to form the pile and the nominal value of base and shaft perimeter to be used in the design shall be agreed before commencement of the work.
7.8.6 Spacing of piles
18.104.22.168 The spacing of piles shall be considered in relation to pile type, length of pile and the ground conditions and their behaviour in groups.
22.214.171.124 The possible interference of one pile with another during installation should be considered when determining pile type, pile spacing, orientation and installation sequence.
7.8.7 Combined piles
Careful consideration shall be given to the joining of elements and to the method of construction of combined piles to ensure adequate bearing capacity, structural strength and durability.
Examples of joints can be seen in Figure A.8 of annex A.
8.1.1 All reasonable precautions should be taken during piling operations (which shall include pile, equipment and material handling ) so as to ensure safety on and around the site and to minimise risk of damage and influence of vibrations and noise on people and adjacent properties.
8.1.2 The execution of displacement piles shall be carried out with a sequence which is in accordance with subclause 7.4.
8.1.3 Before starting piling works a plan of execution describing piling equipment, the installation method, the location of the first pile and a global sequence of installation of the piles should be available and approved.
8.1.4 Where possible trial drives or the initial piles should be installed close to positions of soil investigation.
8.2 Site preparation
8.2.1 The working platform shall be prepared and maintained in such a way that operations can be carried out safely and effectively.
8.3 Equipment and Methods
The piling equipment should comply with EN 996.
8.3.2 Impact hammer
126.96.36.199 Piles, casings or drive tubes shall be driven with a suitable hammer, which allows penetration to the prescribed depth or attains the required resistance without damage and limiting environmental disturbance.
188.8.131.52 For top driven piles the driving system shall be coaxial and sit squarely on the pile or drive tube.
184.108.40.206 The impact velocity and the weight of the ram shall be chosen to suit the pile and soil conditions (see subclause 7.7).
8.3.3 Vibrating hammer
220.127.116.11 Piles, casings or drive tubes shall be driven with a suitable vibrating hammer which allows penetration to the prescribed depth or attains the required resistance without damage and limiting environmental disturbance.
18.104.22.168 The vibrating hammer should be placed centrally on the pile head or drive tube.
22.214.171.124 The centrifugal force, the vibration frequency and the displacement amplitude of the vibrating hammer shall be chosen to fit the pile and soil conditions.
126.96.36.199 A combination of vibratory and impact driving can also be considered where a vibrating hammer is usually used for pitching and initial installation and an impact hammer is used for driving piles to required resistance or depth.
188.8.131.52 If damage to structures or services in the vicinity is likely to occur, piles or tubes should be driven with vibrating hammers regulated independently in eccentric moment and frequency.
8.3.4 Equipment for screw piles
The torque and pressure shall be selected so that piles or drive tube can penetrate to prescribed depth or attain the required resistance without damage and avoiding unacceptable soil disturbance.
8.3.5 Equipment for jacked piles
184.108.40.206 The pressure and reaction system shall be selected so that the pile can penetrate to the prescribed depth or attain the required resistance without damage to the pile or the reaction structure.
220.127.116.11 A calibrated load measuring device shall be incorporated in the jacking system.
8.3.6 Auxiliary equipment
18.104.22.168 When pile cut off level is below ground or water level a follower can be placed coaxial between helmet and pile top.
22.214.171.124 To minimise energy loss the follower should have approximately the same dynamic stiffness as the pile (see 7.8.1).
8.3.7 Drive tube
The drive tube shall be free from significant external or internal variation of the diameter which might prevent the proper formation of the pile.
8.4 Prefabricated piles
126.96.36.199 The specific directives given for handling, pitching and storing the piles shall be followed. Where no specific directives are given the pile elements shall be handled and stored so that they are not overstressed.
188.8.131.52 Where specified, one or more piles shall be restruck after a specified period to determine the effects of time on pile bearing resistance (see subclause 7.8.1).
184.108.40.206 If the driving criteria is not fulfilled on restriking, the bearing resistance of the pile shall be reassessed (see ENV 1997-1, 220.127.116.11).
8.4.2 Prefabricated concrete piles
18.104.22.168 The head of a prefabricated concrete pile which is being impact driven should be protected with a pile cushion to ensure that the impact stresses are reduced and spread evenly on the pile top.
22.214.171.124 The specific instructions given for joining the pile elements shall be followed.
8.4.3 Steel piles
126.96.36.199 The head of a top impact driven steel pile should be covered with a close fitting steel helmet to prevent damage to the pile top.
188.8.131.52 The base of a bottom driven pile shall be strong enough to resist the impact forces of the hammer and to contain the force of the plug material (see 184.108.40.206)
220.127.116.11 Welding and cutting of steel elements
18.104.22.168.1 The pile top shall be cut square to the pile axis before top driving.
22.214.171.124.2 If edge preparation or cutting of the steel elements is necessary this shall be done in accordance with EN 29692.
126.96.36.199.3 Unless otherwise specified in the design, for structural steels in accordance with ENV 1993-5 and EN 10248, joint preparation, welding processes, and the description of the welding procedure, shall be in accordance with the Table 1. For other steel grades, requirements shall be specified.
188.8.131.52.4 When lengths of pile are to be butt-jointed on site, adequate facilities shall be provided for supporting and aligning them prior to welding. The lengths shall be secured in such a manner that eccentricity or angle between the axes of the two segments shall be in accordance with the design and the relevant standards.
Welding operations shall not be performed where affected detrimentally by vibration.
184.108.40.206.5 The metal deposited by welding shall, as a minimum, have the mechanical characteristics equivalent to the minimum specified for the base material.
220.127.116.11.6 Special care shall be taken in order to make sure that the stresses and distortion due to the welding are minimised.
18.104.22.168.7 Welding shall be carried out by appropriately experienced operators.
22.214.171.124.8 Testing and inspection of welds shall be in accordance with Table 1 unless otherwise specified.
Table 1 — Welding testing and inspection criteria for piles and pile details in structural steels
|Welding||Testing and inspection of welds||Type of joint||Type of weld||Joint preparation||Type of electrode||Welding process according to
EN ISO 4063
|Description of welding procedure||Acceptance class for defects EN 25817||Type of testing||Extend of testing|
|butt joint / lap joint a||EN 29692||EN 29692||EN 499||111
|EN 288-2||D||Visual||100 %|
|butt joint / lap joint b||EN 29692||EN 29692||–||D||Visual||100 %|
|a for structural welds
b for non – structural welds
8.4.4 Timber piles
126.96.36.199 Before driving, precautions to prevent brooming shall be taken.
NOTE This may be done by trimming the head of the pile square to the axis and fitting it with a steel or iron ring or by an alternative method shown to be effective.
188.8.131.52 When it is necessary to employ piles formed by two or more lengths the butting surfaces should be cut square to ensure contact over the whole cross sectional area of the pile.
184.108.40.206 The joint should be secured by means of a proven method. See Figures A.8 and A.9 of annex A.
220.127.116.11 After driving, the heads of piles should be cut off square to sound wood and treated with preservative before capping.
8.4.5 Combined piles
When driving, care should be taken not to overstress the joint between the pile elements of different materials.
8.5 Cast in place piles
18.104.22.168 All plant, materials and operations employed in the formation of a pile shall be such as to ensure that the completed pile satisfies the minimum required cross section.
22.214.171.124 The driving of the drive tube shall be in accordance with relevant subclauses in 8.3 and 8.4.
126.96.36.199 The sequence for driving of temporary cased piles shall be such as to prevent damage to any recently completed piles before the concrete in these piles has reached sufficient resistance.
188.8.131.52 Unless otherwise specified or determined from site experience, no piles without permanent casing should be installed within 6 diameters centre to centre of adjacent piles until the concrete in these piles has reached sufficient resistance.
184.108.40.206 If the soil has a characteristic undrained shear strength of less than 50 kPa the distance centre to centre between temporary cased fresh cast in place piles should be increased in accordance with Figure 3 if the concrete has not reached sufficient strength.
- 1 Minimum distance centre to centre / Diameter
Figure 1 — Minimum distance between fresh piles without permanent casing in soft soil
220.127.116.11 When semi-dry compacted concrete is used for pile shafts, the recommended distances may be reduced to half the distances given in Figure 3.
18.104.22.168 Piles that have been lifted should not be redriven except piles in which concrete is placed in a permanent steel or precast concrete tube and in accordance with the specification. Piles without permanent casing should not be redriven unless it can be shown that the pile section can safely withstand the driving force.
8.5.2 Temporary cased piles
22.214.171.124 For a top driven drive tube, the base shall be covered with a shoe or other closure devise to prevent water and soil entering the tube.
126.96.36.199 If the pile shoe be displaced or damaged so that soil or water enters the drive tube the pile shall not be concreted before one or more of the following operations has been completed:
- the tube shall be filled with free flowing material if necessary, withdrawn and redriven; or
- the pile shall be repositioned; or
- if an obstruction is present and can be practically and safely removed the pile shall subsequently be formed in its original location.
188.8.131.52 When the drive tube is impact driven from the bottom concrete, gravel or sand may be used as a plug at the bottom of the drive tube provided it is not damaged during driving.
184.108.40.206 Handling and installation of reinforcement
220.127.116.11.1 The reinforcement cage shall be constructed to enable it to be handled and lowered into the drive tube without damage or distortion.
18.104.22.168.2 Where reinforcement cages are formed or extended on site by welding, the area and quality of the welds shall be adequate for the forces applied during handling and under working conditions after the pile has been concreted, and shall be carried out in accordance with ENV 1992-3.
22.214.171.124.3 Reinforcement cages shall be suspended or supported so as to maintain their correct position during concreting.
126.96.36.199.4 The reinforcement should be placed in the tube prior to concreting.
188.8.131.52.5 Reinforcement installation subsequent to concrete placement may be done for vertical piles, if prior experience in comparable conditions or on trial piles has demonstrated the feasibility of the method of installation.
184.108.40.206.6 Such installation shall take place as soon as possible after the completion of the concreting operation.
220.127.116.11.7 Where reinforcement cages are inserted after concreting, it can be necessary to maintain their position by suitable support.
18.104.22.168.8 The installation process may be assisted by light vibration or the reinforcement may be pulled-in e.g. with a mandrel.
22.214.171.124.9 If reinforcement protruding from the concrete at the pile head is to be bent the internal radius of the bend shall be not less than that stipulated by ENV 1992-3.
126.96.36.199.1 The concreting of cast in place displacement piles shall be done in dry conditions by one of the following three methods:
- 1) using high workability concrete that is discharged in sufficient quantity into the drive tube before and during extraction of the tube;
- 2) by pumping concrete of high workability into the drive tube;
- 3) by using semi-dry concrete that is added in small charges in the drive tube, each charge being expulsed and compacted by internal tamping during the stepwards withdrawal of the tube.
The first and third methods may be combined e.g. fabrication of the pile base (eventual enlarged) with semi-dry concrete, and of the pile shaft with high workability concrete.
188.8.131.52.2 The procedure for placing concrete in dry conditions shall not be followed if there is standing water or soil at the base of the tube. A check shall be carried out immediately before concreting.
NOTE Where there is no soil in the tube, concreting under submerged conditions may be authorized, using a tremie pipe.
184.108.40.206.3 Fresh concrete shall always be poured into concrete which retains its full workability.
220.127.116.11.4 When determining the workability time of the concrete allowance should be made for potential interruptions in the supply and the time required for the placement process.
18.104.22.168.5 The concrete shall be placed in sufficient quantity and with sufficient workability and coherence in order:
- to ensure that no significant quantities of air are entrapped;
- to avoid lifting of the concrete during withdrawal of the tube;
- to prevent separation of the concrete;
- to prevent inflow of soil or water.
22.214.171.124.6 External vibrating or light tamping of the drive tube may be used during tube extraction to improve the concrete outflow and the concrete compaction.
126.96.36.199.7 An adequate head of concrete shall be maintained above the toe of the drive tube during extraction.
188.8.131.52.8 The level of concrete within the drive tube should be maintained at or above working level during the tube extraction operation.
184.108.40.206.9 The pile should be cast to working level unless relevant experience has proven that this is not necessary to ensure integrity and geometry.
220.127.116.11.10 If a semi-dry concrete mix is used, the method of casing extraction shall ensure that the semi-dry concrete does not lift and is adequately compacted and tamped.
18.104.22.168.11 During concreting the volume placed and the level of concrete inside the tube should be checked and recorded.
22.214.171.124.12 The method and the sequence of checking the concrete level should suit dimensions, type of pile and soil conditions and should be agreed prior to the beginning of the work.
126.96.36.199.13 In cold weather with ambient air temperature less than 3 °C and falling, the heads of newly cast piles shall be protected against frost.
8.5.3 Permanently cased piles
NOTE Permanent casing or linings can be used for cast in place piles e.g. to avoid pile necking, excessive pile enlargements or as protection in aggressive soils or groundwater.
188.8.131.52 Handling and installation of reinforcement and concreting shall comply with 8.5.2 and EN 1536.
8.6 Grouted displacement piles
8.6.1 Grouting during driving
184.108.40.206 An enlarged shoe can be used to create along a part or the full perimeter of the pile a space which is filled with grout during driving.
220.127.116.11 The grouting can be carried out at the shoe level through a pipe fixed temporarily or permanently along the pile or through the drive tube.
18.104.22.168 The rate of flow from the pump shall take into account the speed of driving and the size of space around the pile.
8.6.2 Grouting after driving
22.214.171.124 For concrete piles, shaft grouting shall be carried out through permanent grouting pipes fixed to or incorporated in the pile.
126.96.36.199 For steel piles, shaft and base grouting shall be carried out through grouting pipes attached permanently or temporarily to the pile.
188.8.131.52 Grouting shall proceed at appropriate pressures and grouting rates:
- to allow the spread of grout at the interface of the pile with the ground;
- to avoid fracturing of the surrounding ground.
184.108.40.206 After the initial grout has set, second stage post grouting may be carried out.
220.127.116.11 Shaft and/or base grouting shall be carried out to cast in place piles only after the concrete has set and/or cured as speciefied.
8.7 Trimming of concrete piles
8.7.1 Cutting off and stripping of the pile head shall be done carefully to avoid damage to the rest of the pile.
8.7.2 Particular attention shall be paid to the quality of the concrete in the top of the pile. Any defective concrete in the head of the completed pile shall be cut down to sound concrete and made good with new concrete well bonded onto the old.
8.8 Additional methods for special cases
8.8.1 Driving assistance methods
18.104.22.168 Auxiliary methods may be needed to facilitate the driving of piles. Methods include:
- water jetting during driving;
- enlargements on the drive tube or pile base.
22.214.171.124 These methods shall not impair:
- the performance of previously installed piles;
- the stability of surrounding soil (sliding, liquefaction, heave, lateral movements );
- the stability of adjacent structures.
126.96.36.199 The water jetting shall be stopped immediately if the pile or drive tube tends to deviate from its position or inclination.
8.8.2 Ground movement limiting methods
When driving piles in a group and when the piles will cause unacceptable soil movement preboring or coring in accordance with the design, should be used to mitigate the effects.
8.8.3 Working from floating platform
Particular attention shall be paid to the guiding auxiliary structure to ensure the alignment of the piles during driving.
8.8.4 Cast in place base enlargements
188.8.131.52 Methods of base enlargement shall be agreed before commencement of the work. See 7.8.5.
184.108.40.206 Cast in place base enlargements may be formed by ramming compacted quantities of concrete into the ground below the bottom of the drive tube.
220.127.116.11 The concrete consumption as well as the driving energy for the base fabrication shall be measured and recorded as required.
18.104.22.168 For piles which are subject to tensile forces (e.g. by tensile actions from the superstructure or when heave is likely to occur), particular care shall be taken to provide sufficient anchoring of the reinforcement cage in the enlarged base.
9 Supervision, monitoring and testing
9.1.1 A suitably qualified and experienced person shall be in charge of the work.
9.1.2 The person in charge shall be responsible for:
- the conformity of the work with this standard and with any additional specification and agreed working procedure;
- the monitoring of pile construction and keeping of all necessary records; and to
- keep the clients representative and/or designer informed of any variations or deviations from the expected situation or condition of the site or any cases of non conformity.
9.2 Monitoring of pile construction
9.2.1 The monitoring of all works connected with the execution of the various stages of construction of a displacement pile shall be in accordance with the method statement and piling plan made up in accordance with the design and ENV 1997-1.
9.2.2 The pile construction process shall be monitored including previously installed piles and all relevant data indicated in 10.3 and when required those indicated in 10.4 shall be recorded.
9.2.3 The effects of piling close to sensitive buildings or potentially unstable slopes should be monitored. Methods include vibration, pore pressure, deformation and inclination measurement. The measurement should be compared to criteria for acceptable performance.
9.2.4 Frequency of monitoring shall be specified and agreed before commencement of piling work.
9.2.5 Records of monitoring shall be provided within an agreed period and kept on site until the completion of the piling works.
9.2.6 All instruments that are used for monitoring the pile installation and/or the effects of installation shall be suitable for the purpose and calibrated.
9.2.7 All non conformance shall be notified.
9.2.8 The full driving record of a proportion of the piles should be recorded in order to establish whether the soil conditions correlate with those used in the design.
This should also include:
- for impact hammers the hammer drop height and weight or hammer energy together with number of blows per unit of penetration;
- for screw piles the torque and pressure applied;
- for vibrated piles the power rating, amplitude and frequency and rate of penetration;
- for jacked piles force applied to the pile.
9.2.9 Where driven bearing piles are driven to a final set, energy and set shall be measured.
9.2.10 Where heave or lateral displacements are likely to be detrimental to pile integrity and performance, pile top level and plan location readings with respect to a stable reference level mark should be taken before and after driving of neighbouring piles and/or after possible excavations.
9.2.11 Prefabricated piles, which have risen more than the acceptable limits, shall be driven back to their original design criteria.
NOTE For piles, when it is not possible to redrive the pile, a load test to determine its load and settlement characteristics would allow the overall performance of the pile group to be established.
9.3.1 The testing of piles shall be in accordance with relevant ENV 1997-1 or with the specifications in the design.
9.3.2 Pile tests can be used for:
- assessment of design parameters;
- verification of pile design;
- proof of resistance – deformation characteristics in the general range of specified actions;
- compliance with the specification;
- proof of the integrity of a pile.
9.3.3 Pile tests may consist of:
- static pile load tests:
- maintained load pile test;
- constant rate of penetration pile test;
- dynamic pile load tests (high strain);
- integrity tests:
- sonic test, dynamic integrity test (low strain);
- sonic coring;
- dynamic integrity test (high strain);
- control tests:
- concrete core drilling for obtaining material samples;
- inclinometer test to check the verticality, inclination, bending of a pile from a pre-placed tube system.
9.3.4 Where static load tests are used the design and installation of the various reaction items shall be in accordance with relevant codes and method statements.
9.3.5 Static and dynamic load testing of piles should be carried out after sufficient time, taking account of any gain in strength of the pile material, and with regard to changes in soil resistance due to pore pressure effects.
9.3.6 Dynamic and integrity tests shall be carried out using equipment built and approved for the purpose. These tests are required to be interpreted by persons competent in this area, who shall also have a knowledge of the techniques of piling and experience of the specific ground conditions.
9.3.7 The records of any testing shall provide:
- the testing method and procedure;
- the test result;
- the conclusions on the pile test.
10.1 The records shall be in accordance with ENV 1997-1.
10.2 The site records shall consist of two parts.
Part 1: References and general information regarding:
- the type of pile;
- the execution method; and
- the reinforcement and concrete specification, steel quality, timber quality. Part 2: Particular information related to the execution procedure.
10.3 The general information part shall be similar for the different types of piles and construction methods and shall contain the details listed below.
|foundation (piling) contractor||X|
|pile type/size / quality||X|
|concrete placement details||(X)|
|prefabricated pile manufacturer||(X)|
X necessary information
(X) information as applicable
10.4 The particular information part shall be specific to the type of pile and the construction method and should contain the details listed in Table 2 below.
|Data||Prefabricated displacement piles||Cast in place displacement piles|
|Pile reference number (location)||X||X|
|Length of prefabricated pile||X||(X)|
|Date and time of driving, redriving||X||X|
|Date of concreting (manufacturing)||(X)||X|
|Depth from ground level at pile position to pile toe||X||X|
|Pile head level as constructed||X||X|
|Pile cut-off level||X||X|
|Type, weight, drop and mechanical condition of hammer and equivalent information for other equipment||X||X|
|Number and type of cushion used and type and condition of follower used during driving of the pile||X||X|
|Length and details of reinforcement||(X)||X|
|Final set of pile or pile tube in millimetres per 10 blows or number of blows per metre or part of metre penetration||X||(X)|
|Concrete mix or grade||X||X|
|Volume of concrete supplied to pile.||–||X|
|All information regarding obstructions delays and other interruptions to the sequence of work||X||X|
|Number and location of joints||(X)||(X)|
|Length of permanent casing or liner||–||(X)|
|X necessary information
(X) information as applicable
10.5 The additional particular information details listed in Table 3 below should be recorded.
|Data||Prefabricated displacement piles||Cast in place displacement piles|
|Standing groundwater level from direct observation or given site investigation data||(X)||(X)|
|Ground level at pile position at commencement of installation of pile (commencing surface)||(X)||(X)|
|Working platform level||(X)||(X)|
|The sets taken at intervals during the last 3 m of driving||(X)||(X)|
|Temporary compression (elastic deformation) of ground and pile from time of a marked increase in driving resistance until pile reached its final level||(X)||(X)|
|Diameter and length of prebore/precore||(X)||(X)|
|Depth and type of driving assistance||(X)||(X)|
|Details of any surface coatings||(X)||(X)|
|Pore pressure readings||(X)||(X)|
|X necessary information
(X) information as applicable
10.6 As appropriate, the information can be provided in the form of:
- individual records compiled for each pile; or
- summary records for groups of piles of the same type, executed with the same method.
10.7 Details of recording and the format of the site records shall be agreed before the commencement of the piling.
10.8 All records shall be signed by the contractor's representative and by the client's representative unless otherwise agreed.
11 Specific requirements
11.1 During the execution of displacement piles, the national standards, specifications or statutory requirements shall be complied with.
Safety aspects including:
- security of the site;
- operational safety of driving and auxiliary equipment and tools;
- safety of the working practices;
shall be complied with. Equipment should be in accordance with EN 996 and EN 791.
Particular attention shall be given to all processes requiring personnel operating alongside heavy equipment and heavy tools.
11.3 Noise and vibration hindrance
Where people in the neighbouring might be exposed to noise and/or vibration, the expected levels of noise and/or vibration should be shown either by test driving or by comparable experience, and the acceptability of the process evaluated. Where necessary, monitoring during execution of the works should be undertaken to confirm that the levels are kept within agreed limits.
11.4 Environmental damage (pollution)
11.4.1 Environmental damage that can be caused by the piling work shall be kept to levels given.
11.4.2 Such environmental damage can be caused by e.g.:
- ground pollution,
- surface water pollution,
- groundwater pollution,
- air pollution.
NOTE The kind and extent of possible nuisance or environmental impact depends on e.g.:
- the location;
- the soil conditions;
- the choice of pile installation process and sequence.
11.5 Impact on the surrounding structures and slopes
Where sensitive structures, installations or unstable slopes are present in the vicinity of the site or possible sphere of influence of the piling works, their condition should be carefully observed and documented prior and during to the execution of the piling works.
Classification and examples
NOTE 1 Prefabricated piles can be solid or hollow and can be extended by welding, splicing or jointing.
NOTE 2 Methods of driving piles apply to several types and requirements are noted in 8.3.
NOTE 3 Additional methods to improve pile capacity and assist installation are noted in 8.8.
NOTE 4 Both prefabricated and cast in place piles can be grouted. Requirements and possibilities are noted in 8.6.
Figure A.1 — Family tree chart for displacement piles
a) Example of driven cast in place pile
b) Example of screwed cast in place pile
c) Example of prefabricated concrete pile (round or square)
d) Example of steel pile (round or H)
e) Example of prefabricated concrete conical pile (round or square)
f) Example of cast in place pile with enlarged base
g) Example of cast in place pile with enlarged base
h) Example of cast in place cased pile with enlarged base
i) Example of pile with base of expanded body
j) Example of enlarged base on steel H-pile
Figure A.2 — Exemples of shafts and bases of displacement piles
a) Examples of cross sections of precast concrete piles
b) Example of cross section for cast in situ pile with permanent casing
c) Example of cross section for grouted pile
d) Examples of cross sections for steel piles
e) Exemples of cross sections of steel piles formed from steel sheet piles
f) Exemple of concrete sheet piles forming a wall
Figure A.3 — Examples of cross sections for displacement piles
a) Example for H-pile
b) Example for H-pile
- 1 Special hardened rock point
c) Example of rockshoe for tubular steel and concrete piles
d) Example of rockshoe for sloping rock
Figure A.4 — Examples for toe protection for prefabricated displacement piles
1. Drivinging in of drive tube
2. Placing of reinforcement cage
4. Extraction of drive tube
a) Construction of screw cast in place displacement pile
1. Driving in of drive tube
2. Placing of reinforcement cage
3. Concreting and extraction of drive tube
4. Constructed pile
b) Construction of driven cast in place displacement piles
Figure A.5 — Examples of construction of cast in place displacement piles
- 1 Leaders
- 2 Impact hammer
- 3 Hammer cushion
- 4 Helmet
- 5 Pile
- 6 Base machine
- 7 Working platform
Figure A.6 — Example of piling rig with impact hammer
- 1 Locating pin
- 2 Locking plug
- 3 Push and Twist
Figure A.7 — Examples of mechanical joints for prefabricated concrete displacement piles
- 1 Steel tube cast into concrete top pile and impact driven into the timber pile
- 2 Concrete pile element
- 3 Reinforcement
- 4 Steel tube
- 5 Timber pile element
Figure A.8 — Example of combined pile
- 1 Plate tarred on inside face
- 2 Dowel
- 3 Screw position
Figure A.9 — Examples of joint in squared timber pile
Figure A.10 — Example of tool for screw pile
- 1 Prefabricated displacement pile
- 2 Grout material
- 3 Enlarged shoe
- 1) Grout material is injected through a pipe at shoe level during driving
Figure A.11 — Example of grouted pile
- 1 Displacement pile
- 2 Grout supply line
- 3 Grout
- 4 Non return valve
- 1) Displacement pile is driven to final depth
- 2) High pressure grouting is done after driving
Figure A.12 — Example of post grouted pile
a) Cast in place displacement pile
b) Prefabricated displacement pile
- 1 Working level
- 2 Pile top
- 3 Casting level
- 4 Cut off level (trim level)
- 5 Pile head
- 6 Pile shaft
- 7 Pile bottom
- 8 Pile base
- 9 Toe level
- 10 Pile shoe
Figure A.13 — Displacement piles, termes and levels