9 Supervision and monitoring

9.1 Supervision

9.1.1 A suitably qualified and experienced person shall be in charge of the execution of the work.

9.1.2 The person in charge shall be responsible for:

  • the conformity of the work with this European 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 client's representative and/or the 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 specific procedures for verification, control and acceptance shall be established before the commencement of the works.

9.2.2 The pile construction process shall be monitored and all relevant data shall be recorded, including:

  • setting out, pile type, dimensions and depths;
  • excavation procedure, tools and equipment;
  • installation of casings;
  • stratification of ground and groundwater levels;
  • obstructions;
  • use of a stabilizing fluid;
  • levels of water or of stabilizing fluid in the pile bore;
  • construction of pile sockets;
  • construction and control of enlargements;
  • cleaning of pile bore;
  • checks of stabilizing fluid;
  • reinforcements type, dimensions, assembly and length;
  • reinforcement installation depth and position;
  • installation of precast concrete elements or reinforcement tubes or sections;
  • concreting in submerged or dry conditions;
  • concreting of continuous flight auger piles;
  • site mixed or ready-mixed concrete;
  • concrete grade, composition and consistency;
  • concrete placement, quantity, duration, rise and final elevation;
  • recovery of temporary casings;
  • recovery of the tremie pipe;
  • shaft and/or base grouting: mix composition and properties, zone of application, time, supply rate, pressure and quantity.

9.2.3 The duration's of the respective operations should also be recorded.

9.2.4 All non conformance's shall be notified.

9.2.5 During excavation, the ground behaviour shall be observed and any unforeseen change or feature that might be important for the design shall be communicated to the supervisor and the designer.

NOTE: Examples of the details and frequencies for the monitoring are given in tables 6 to 15.

9.2.6 The records shall be submitted to the client's representative and/or to the designer and shall be signed as agreed.

NOTE: Records are dealt with in clause 10, Sample records are provided in annex B.

9.2.7 After preparation of the piles for their structural use, an "as built" record plan shall be drawn up showing positions and dimensions of piles together with pile head and founding levels.

9.2.8 The record plan, the pile monitoring records and any other piling documentation shall be kept as required by the contract and/or the statutory requirements.

Table 6: Monitoring of setting out
  Subject Control Purpose Frequency Remarks
1 main axes survey setting out of piles at commencement of works establishment of main axes for time of execution
2 working platform survey, visual check elevation, level ness, size, stability each construction area  
3 - pile position,
- pile rake
- plumb-line
- tape
- spirit level
check of deviations against geometrical construction tolerances every pile
- before start of excavation
- after excavation
- after completition
Table 7: Monitoring of excavation
  Subject Control Purpose Frequency Remarks
1 lead-in tube (guide wall) - diameter
- width
- depth
- stability of top of uncased excavations
- conformity with the design
each pile can be omitted for circular piles with D < 0,6 m
2 condition and dimensions of tools, casings - visual check
- measurement
adequacy before and during use (as applicable)  
3 use of tools, (general) - progress of excavation
- efficiency
- over excavation
- supervision
- recognition of (changing) ground conditions
- depth
- times
- tool changes
4 use of tools, (submerged) as above, plus
- operation speed
avoid piston effect continuously  
5 casing installation measurement advance of casing during excavation continuously particularly important when casing advance ahead of excavation is necessary
6 water level measurement stability of pile bore continuously  
7 excavated material visual check recognition of
- strata and
- soil variations
continuously samples to be kept as necessary
8 pile depth (completion of excavation) measurement:
- depth
- slope (measurement of inclined bearinq strata)
achievement of specified depth each pile verification can also be effected with calibrated tool
9 enlargement measurement (by operational control of equipment) (visual inspection) - size
- slope of walls
- alignment
each enlargement measurement preferred through calibrated equipment
10 cleaning of base - grab
- sounding
- (visual inspection)
- clean interface to bearing stratum
- pile performance
each pile  
11 standing water on base - tape
- visual inspection
avoid segregation and contamination of concrete each pile  
Table 8: Monitoring of stabilizing fluid
  Subject Control Purpose Frequency Remarks
1 supply, storage check supply in line with consumption continuously supply/storage should cater for sudden loss
2 level in pile bore check stability of hole continuously  
3 properties of suspension - density
- consistency (Marsh value)
- fluid loss
- alkalinity
- sand content
- with 6.5.2 and 6.5.3 or
- national standards
each pile fresh fluid
- before concreting
- after desanding, before reuse
Table 9: Monitoring of reinforcement
  Subject Control Purpose Frequency Remarks
1 delivery of materials - delivery documents - dimensions conformity each delivery  
2 dimensions measurement conformity spot check  
3 fabrication of cages - dimensions - spacing of longitudinal bars - spacing of transverse bars - fixing - rigidity conformity each cage where welding is carried out: check in accordance with the specification for the reinforcing steel
4 spacers - material - size - quantity - distribution - conformity - deviation of installation each cage inner dimension of the casing (if any) to be taken into account
5 installation of cages - survey - measurement deviation of installation each cage  
6 reinforcement tube/ steel section - survey - measurement deviation of installation each tube or section  
7 special reinforcement accordance to special procedure conformity accordance to special procedure  
8 embedment - pipes for sonic coring - monitoring devices - box-outs - position - depth - connections with cage - protection during installation - protection during concrete placement - conformity - reliability each cage  
Table 10: Monitoring of fresh concrete
  Subject Control Purpose Frequency Remarks
1 continuity of supply check continuity of placement before placement  
2 concrete
- grade
- composition
delivery document conformity each truck  
3 consistence - slump or
- flow table
- conformity
- workability
- each truck (truck delivery) or
- every 10 m3
4 ambient temperature thermometer protection of newly cast piles when required  
5 concrete temperature thermometer - conformity
- workability
when required frequency to be increased when in doubt
6 workability time workability check on fresh concrete check of duration of workability - when required or
- in doubt
test is carried out in parallel to concrete placement
Table 11: Monitoring of concrete placement in dry or submerged conditions
  Subject Control Purpose Frequency Remarks
1 concreting pipe, tremie pipe
- conditions
visual check - cleanliness
- watertightness
- internal smoothness
each pipe before or during installation  
2 - internal diameter
- external dimensions
check/ measurement - compatibility with aggregate sizes
- free movement inside reinforcement
- each set of pipes
- each size of pile
3 - composition (sectional lengths) check/ measurement preparation for recovery each set of pipes  
4 - installation depth measurement avoid segregation at commencement of concrete placement each pile tremie pipe should rest on the bottom
5 - separation of concrete from water inside tremie pipe check avoid segregation each pile use e.g. of
- bottom lid
- ball or
- plastic chips
6 - immersion of tremie pipe during concreting and recovery check depth of concrete against length of tremie pipe - maintenance of sufficient immersion
- avoid segregation
- avoid contamination of the concrete
continuously - sufficient immersion also during recovery of tremie pipes
- observe any accumulating water inside the tremie pipe
7 immersion of casing during recovery check depth of concrete against tip of casing - maintenance of sufficient of immersion
- avoid necking
- avoid segregation and contamination of concrete
continuously observe any sudden drop or rise of concrete
8 casting level depth measurement sufficient height above cut-off level each pile  
9 backfilling empty bore check site safety each pile  
10 concrete volume compare consumption with theoretical excavation volume detect excessive overbreak or necking each pile (where possible) detailed monitoring, including records of concrete slump during casing recovery, can be necessary
11 pile head after casting visual check detect excessive water flow each pile (where possible) some bleeding will always result from self compaction of the concrete; excessive bleeding might be an indication of possible shaft inclusions
Table 12: Monitoring of CFA piles
  Subject Control Purpose Frequency Remarks
1 conditions and dimensions of
- auger
- cutting head
- closure device
- visual check
- measurements
adequacy before commencement of boring  
2 excavation process check
- speed of rotation and of
- penetration
limit over excavation continuously  
3 excavation depth / founding layer check
- speed of rotation
- penetration
- torque (optional)
- material
- depth
conformity each pile some information may be relative and not conclusive
4 commencement of concreting check concrete flow check for blockage each pile  
5 concreting check
- concrete pressure
- concrete flow and
- consumption corresponding auger withdrawal
complete filling of bore with concrete each pile, continuously  
Table 13: Monitoring of pre-packed piles
  Subject Control Purpose Frequency Remarks
1 cleanliness of excavation check, measurement (tape with plumb bob) interface of pile to bearing stratum each pile  
2 grouting pipes - diameter
- number
- installation depth
provision for the grouting process each pile site trials recommended for the verification of the spread of grout and the distribution of grouting pipes
3 aggregate - size
- quantity
filling complete volume each pile  
4 grout properties - composition
- consistence
- workability time (setting time)
- bleeding
- admixtures
- workability
- strength
each batch  
5 grouting process - pumping rate
- pressure
- consumption
- withdrawal of grouting pipes
- proper grout distribution
- provision of continuous shaft
each pile, continuously  
6 grout strength compressive strength conformity with specification each pile  
Table 14: Monitoring of external grouting and of shaft/base grouting
  Subject Control Purpose Frequency Remarks
1 grouting pipes - diameter
- number
- distribution
- installation depth
- fixing to reinforcement cage
- arrangement of valves
conformity with special method statement each pile  
2 (flexible) box structure - area
- contact to base of excavation
- sealing to concrete column above
- fixing to cage
- function and fixing of grouting and vent pipes
- maintenance of void after concrete placement
- check apparatus before installation
each pile  
3 grouting process - pumping rate
- pressure
- consumption
- distribution of grout
proper distribution of grout each pile, continuously  
Table 15: Monitoring of cutting-off
  Subject Control Purpose Frequency Remarks
1 concrete at cut-off level visual check
- concrete quality
- pile section
- evenness
- existence of cracks
- condition of reinforcement
- concrete cover
provide satisfactory conditions for connection of pile to superstructure each pile If concrete quality is found to be inadequate at the design cut-off level, the pile is to be cut further down and to be reconcreted after the formation of a construction joint.

9.3 Pile testing

9.3.1 General

NOTE 1: The principal requirements for pile testing are contained in ENV 1997-1. The following notes contain general remarks, which may be supplemented by national application documents, as applicable (as long as respective European Standards are not available).

NOTE 2: Pile tests may be used for research or investigation purposes for proof of:

  • resistance/deformation characteristics in the general range of specified actions;
  • the soundness and proper construction of a pile.

NOTE 3: Pile tests can consist of (see clause 3):

  • maintained load tests;
  • constant rate of penetration tests;
  • dynamic pile tests for the determination of the pile capacity; and
  • integrity tests which measure the acoustic or vibrator properties of the pile in order to determine the presence of possible anomalies within the pile body.

NOTE 4: The application of various procedures is as indicated in table 16 below. Definitions of the different tests are provided in clause 3.

Table 16: Application of some test procedures
Type of test Application
Proof of ultimate pile resistance Proof of working deformation range Structural soundness (integrity)
Maintained load pile test yes yes sometimes possible 1)
Continuous rate of penetration test yes 1) indicative for non-cohesive ground if slow enough no
dynamic pile test yes 1) possible 1) yes 1)
Integrity test no 1) no yes 1)
1) Subject to interpretation

NOTE 5: The only test which can derive the ultimate resistance directly is the maintained load test if loads are sufficient and held constant for a long enough period. Other tests require subsequent interpretation. Similarly, dynamic testing methods cannot measure consolidation or creep under load. Any approximations made to the results for the purpose of establishing load/settlement relationships should therefore be made clear in test reports.

9.3.2 Axial loading tests The strength of the pile shall be such that at the time of testing, its structure will not be damaged. Additional material strength testing can be necessary for this purpose. In maintained load tests and constant rate of penetration tests, the pile head displacements in the direction of the load shall be determined by at least two measuring devices, the accuracy of which shall be at least 0,1 mm. The transverse displacements of the pile head should also be measured. In maintained load tests, loads should be maintained constant at each of at least 6 stages for a specified duration. Unless otherwise agreed the displacement rate should be less than 0,1 mm/20 min at the end of each stage. In continuous rate of penetration tests the rate of displacement shall be kept constant at approximately 1 mm / min throughout the period of the test. Other rates of displacement may be agreed prior to testing. During each test there should be at least two independent measuring devices for load and they should check against each other to exclude gross errors. All force measuring devices shall be calibrated at least once annually. As long as European Standards are not available different national requirements or specifications shall be observed. For dynamic load tests the pile shall be allowed to gain sufficient strength after installation and before testing. Dynamic and integrity tests shall be carried out using equipment built and approved for the purpose and 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. The apparatus shall be used in accordance with the manufacturer's instructions and the pile shall be prepared for the purpose of testing in an appropriate manner. In tests where the load is directly applied to the pile, either using kentledge, ground anchors or anchorage piles, the loading arrangements shall be such that the equipment remains stable and does not bring about soil displacements liable to change considerably the behaviour of the pile. The supports or anchorages of a reaction system should observe the following minimum clear distances to the test pile:

  • a) supports of kentledge: a ≥ 3 × D
  • b) bond lengths of vertical anchorages: a ≥ 3 × D and a ≥ 3,0 m;
  • c) bond lengths of inclined anchorages: a ≥ 5 × D and a ≥ 5,0 m. On completion of tests the results, together with full details of the pile tested, its location and a summary of ground conditions, shall be presented without undue delay in a report to the employer, using graphical and numerical form where appropriate. Where rapid loading has been applied, full correlation data with maintained load tests in similar ground shall be provided.

10 Records

10.1 The site records shall consist of two parts; the first making reference to the site and the general information including:

  • the pile (type, dimensions...);
  • the construction method; and
  • the reinforcement and concrete specification.

The second part shall contain particular information related to the construction procedure.

10.2 The general information part shall be similar for the different types of piles and methods and shall contain the details listed in table 17 and table 18.

10.3 The particular information part shall be specific to thes type of pile and the construction method and shall contain the details listed in table 19.

10.4 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, constructed with the same method.

10.5 Details of recording and the format of the site records shall be agreed before the commencement of the piling.

NOTE: Sample construction records are provided in Annex B.

Table 17: General information of the site
  Subject necessity
1 site location X
2 contract identification X
3 structure X
4 main contractor (X)
5 foundation (piling) contractor X
6 client/employer (X)
7 engineer / designer (X)
X      necessary information
(X)   information as applicable
Table 18: General information of the procedure
  Subject necessity
1 pile diameter/size/enlargements X
2 excavation method X
3 details of stabilizing fluid X
4 cleaning method X
5 reinforcement details X
6 concrete specification X
7 concrete placement details X
X   necessary information

10.6 Records of any integrity testing shall provide

  • the reason for the testing,
  • the testing method and procedure,
  • the test results, and
  • the conclusions on the pile integrity.

NOTE: Recording requirements for static or dynamic load testing and the format of the load test report are provided in ENV 1997-1.

10.7 All records shall be signed by the contractor's representative and by the client's representative unless otherwise agreed.

Table 19: Schedule of as-built information to be provided
Nr Subject cased/uncased excavation excavation supported by fluids continuous flight auger piles
1 pile reference number X X X
2 excavation times X X X
3 interruptions of excavation X X X
4 removal of obstructions X X
5 temporary/permanent casing X
6 depth of casing X
7 lead in tube/guide wall X (X)
8 depth of lead in tube X (X)
9 depth of pile X X X
10 stratification log X X (X)
11 ground water table X X (X)
12 cleaning X X
13 stabilizing fluid
- properties
14 - recovery X
15 reinforcement
- length
16 - suspension X X X
17 - installation time X X X
18 concrete placement
- dry/submerged conditions
19 - duration X X X
20 - interruptions X X X
21 - volume X X X
22 - pressure X
23 - site tests X X X
24 recovery of casing X
25 recovery of lead in tube X (X)
26 backfilling empty bore X X X
27 precast concrete elements
- type and details
28 - installation X X
29 - external grouting process X X
30 - properties of self hardening slurry X X
31 - suspension X X
32 - cover X X
33 external grouting
- details of grouting pipes/box structure
X X (X)
34 - grout properties X X (X)
35 - grouting process X X (X)
36 prepacked piles
- details of aggregate
37 - details of grouting system  
38 - grout properties X
39 - grouting process of bore X
40 shaft and base grouting
- grouted area
41 - details of grouting system X X X
42 - grout properties X X X
43 - grouting process X X X
44 construction deviations
- position
45 - rake X X X
X necessary information
(X) information as applicable
— not applicable

11 Specific Requirements

11.1 Regarding:

  • safety on the site;
  • safety of the working practices;
  • legality of manual works and inspections inside excavations; and
  • operational safety of piling and auxiliary equipment and tools;

the respective national standards, specifications or statutory requirements regarding execution of bored piling works shall be observed, as long as respective European Standards are not available.

11.2 Equipment shall be in accordance with EN 791.

11.3 Particular attention shall be drawn to

  • all processes requiring men operating alongside heavy equipment and heavy tools,
  • the danger of open holes,
  • manual working procedures and inspections carried out inside excavations.

11.4 Excavation by hand should be kept to a minimum.

11.5 Excavation by hand shall be restricted to dry conditions where the ground is naturally stable or where support of the excavation walls is continuously be maintained.

11.6 Employment of personnel inside a bore is permitted only if the available space for the work is at least 0,75 m in diameter.

11.7 Nuisance and/or environmental damage that can be caused by the piling work shall be kept to a minimum.

11.8 Such nuisance and/or environmental damage can be caused by:

  • noise;
  • ground vibration;
  • ground pollution;
  • surface water pollution;
  • groundwater pollution; and
  • air pollution.

NOTE: The kind and extent of possible nuisance or environmental impact depends on:

  • the location;
  • the working method;
  • the actual processes.

11.9 Regarding nuisance and environmental protection, for each particular situation

  • the national requirements (as long as respective European Standards are not available), and
  • the local requirements shall be observed.

EN 1536:1999 Execution of special geotechnical work – Bored piles