00-Slides-IEM Course-Site Supervision-Displ Piles-18 Jun 22 - Copy.pdf

by
Ir. Neoh Cheng Aik
caneoh@gmail.com
18 Jun 22
IEM Site Construction & Supervision Course, 18 Jun 22
Site Construction & Supervision of
Displacement Pile Foundations
(driven/jacked RC piles/Spun piles)
1

Scope of Presentation
1. Introduction
2. Role & Responsibility of Site Supervision
3. Overview of Displacement Pile Installation Practice
4. Common problems for Displacement Pile Installation
5. Case histories
6. Q & A - Commonly Asked Questions
7. Conclusions
*This presentation is to discuss the role & responsibility of site
supervision aimed to equip the site supervisors with information
& knowledge related to proper installation of common
displacement piles (driven/jacked RC/spun piles) so as to enhance
their expertise to ensure compliance with CP/design drgs/Spec.
To stimulate awareness and understanding about the common
defective constructions & typical malpractice will also be
elaborated with case histories.
2

1. INTRODUCTION-1
1.Displacement piles are piles installed into the ground by driving/
jacking/vibration/screwing without excavation or removal of
materials from the ground except for limiting heave, vibration,
removal of obstructions or to assist penetration (BS EN 12699).
2.Primary responsibility of displacement pile designers is to provide
Drgs & Spec substantiated by scope of design verification/analysis to
show in compliance with CP with particular reference to ensure the
piles have adequate structural strength & safe geotechnical
resistance to undertake not only the expected superstructural loads,
but also the loads/forces/stress arise from ground movement,
handling & installation stresses, etc. Pile selection criteria?
3.In order to ensure pile construction is properly carried out at site in
compliance with CP/design drgs & Spec, piling work shall be
supervised by competent & suitably qualified person with
comparable experience (BS EN 12699).
4.“Lack of quality assurance and quality control by contractors and
lack of proper site supervision by suitably qualified engineers” is
commonly cited as one of the major causes for project
problems/failures (delay, cost overrun, distress, etc.)
3

The Gist of issues to be discussed*
1. What are the role & responsibility of displacement pile supervisors (CRE/RE)?
2. In order to discharge the responsibility well, what are the basic info & knowledge
that a displacement pile supervisor should learn & acquire? Plus principles?
3. What are the indispensable CP/standards for displacement pile supervisors to
refer regularly until at fingers’ tip?
4. What are the common displacement pile installation methods & the basic piling
rig/tool requirements, procedures & proper construction controls?
5. What are the critical information sought from SI report for displacement pile
construction planning & controls? Uncontrolled fills/ex-mining sites/obstructions
6. For precast RC & prestressed concrete piles, what the important scope of
inspection & QC that can affect performance after installation? What are the
important info that should be sought from the pile manufacturers? (Designer is
responsible for adequacy for capacity, for driving stresses, Mc at 0.2mm/0.1mm
crack width, etc. Site supervisors are responsible for the piles supplied to site are
really in compliance with the Drgs & Spec for the project). Physically how to
execute these obligations/responsibilities?

The Gist of Issues to be discussed-2
7. For driven concrete piles, what are the criteria to choose hammer type/wt &
drop height? Pile termination criteria? Driven to appropriate set & driven to
refusal? Redriving tests & false set phenomenon? Ground heave & pile heave?
Pile set up & relaxation? Driving assistance? Drivability analysis? How???
8. For jacked concrete piles, how to set pile termination criteria? Basis? Common
problems that may be encountered: disputes, increase cost & delay?
9. For displacement concrete piles, adequacy in structural stiffness (grade of
concrete, reinforcement, workmanship, pile dimensions, etc.) is very important
for transportation, handling and during installation & in service. Pre-installation
conditions can be assessed by visual inspection & testing. How to assess the
installation stresses & adequacy of pile shoe design & pile joints before & after
installation?
10. Scope, frequency & methods of design validation for driven/jacked concrete
piles? Post-installation tests to verify & validate the structural integrity &
performance (pile capacity & settlement)? Acceptance criteria & basis? 5

*The most important responsibility of supervisors is to inspect (look closely & critically) to ensure
conformity to Specs & drawings. To discharge this responsibility, the supervisors have to be well-
versed with Specs, drawings & construction requirements of piling processes as stipulated by BS EN
12699:2015, MS 1314 & BS 8004: 1986.
Displacement
Pile
Installation
(driven/jacked
concrete piles,
etc.)
Role &
Responsibility
of Supervisors
To represent the Project Owners & take care of their interests to
ensure only sound piles are constructed.
To inspect with due care, diligence & skill so as
to ensure conformity to Specs & drawings
To record the as-built conditions with due care, diligence & skill
To report any non-conformity & abnormalities
with care, diligence & skill
Piling
Processes,
Construction
Requirements
& scope of
inspection &
monitoring
Pre-installation checklist: method statement, concrete pile factory
visit, product QA system, test certs, product inspection & sample
testing, format of recording, installation checklist, etc.
Preliminary test piles, sample checks for ground heave, pile heave
for big pile group, sample redriving tests, check pile set-up &
relaxation, driving test monitoring, full continuous PDA tests,
establish pile termination criteria for working piles.
Production/working piles-scope of inspection & monitoring.
Evaluation of records, selection of working piles for tests (integrity
& capacity) & acceptance criteria
Preparation of as-built drawings & check pile deviations. Any
remediation?
Pile cap construction checklist
6

Studies by Mandolini, et al (2010)
7
Pile Type Qu/W COV (Qu/W)
Bored 12.1 0.26
CFA 37.5 0.25
Driven 73.1 0.08

Survey of use of foundations in construction
8
Pile support cost=
U$ 8.5 to 21/ton.
For similar structure
& ground conditions,
Q/W=73 for driven piles.
Q/W=21 for bored piles.
Van Impe (2003) has
cited: Bored & CFA
account for 50% of
the world pile market
& the remaining
mainly by driven
piles.
JKR survey in 1990:
85% driven/jacked
concrete piles, 10%
RC footings & 5%
micropiles/bored
piles.

Ground-related Risks (Risk = Probability*Impact)
• 80-85% of (European) building failures are related to ground problems -
Brandl, 2004. Residual risks are unavoidable, because ground is the
greatest uncertainty in civil engineering -Brandl, 2000
• 50% of project delays caused by adverse ground conditions –
Chapman & Marcetteau, 2004
• ―…Despite the absence of definitive statistics, most experts would
agree that the incidence of geotechnical disasters has increased over
the last 20 years‖ -David E Sherwood, 2011.
• 90% of dam failures occurred because of oversights that could and
should have been avoided – Peck, 1981
• 80% of civil engineering failures were due to human, organizational
and knowledge uncertainties, as opposed to engineering issues. – Bea,
2006
• 88% of excavation pit failures in Netherlands could have been avoided
with proper risk management prior to work. – Van Tol et al 2009
• 60% deep excavations failures in the Netherlands caused by not
applying existing knowledge – Van Tol 2007
• In brief, most of the ground-related problems/risks are due to human
factors (designer & supervisor) as the result of ignorance,
oversights/carelessness & inadequate SI.
9

Be cautious of over-confidence!
1958 Board of Consultants (USA): “The Board recognizes that leakage risks
resulting from unknown and indeterminate ground conditions are involved. It
believes however, that the known conditions are sufficiently favourable to
justify taking these risks”
80 years and >$3.6M over budget, the dam still does not meet its intended
purpose, due to complex geologic conditions encountered.
10

Comparison of disp piles & non-disp piles*
Displacement Piles (driven/jacked
concrete piles)
Non-displacement Piles
(bored piles)
Pile formation Displacement piles are usually
prefabricated or formed off-site under
factory conditions & they can be
visually inspected/tested before
installation by driving/jacking.
Non-displacement piles are cast insitu in
bored holes in differing conditions
(dry/wet/slurry as required by the subsoil
conditions) & these will result in significant
differing integrity & capacity problems.
Qu/W for a
specific site
Qu/W=High (about 73 for concrete
piles). Has ground vibration &
noise problems
Qu/W=Low (about 12 for concrete piles)
COV for Qu/W 0.08 (small COV means Qu/W is less
influenced by constriction practice)
0.26 (large COV means construction
practice can affect Qu/W more)
Rate of
construction
Generally faster & cheaper, but limited
pile capacity may result in large pile caps
causing pile group efficiency & pile
heave problems.
Generally slower & expensive, but can
be sized to have large pile capacity to
achieve small pile group of less than 5.
Post-
construction
testing
Proper driveability analysis & detail
records can give indicative integrity &
capacity conditions that should be
validated by PIT (3-5%) & MLT/PDA (2-
5%)
Comprehensive records (BS EN 1536) are
useful to check pile integrity & capacity which
should be validated by PIT (5%), proof coring
& MLT/BiDLT/RLT /PDA (2-5%)
11

ADVANTAGES of Displacement Piles DISADVANTAGES of Displacement Piles
Displacement pile can improve soil
density & capacity especially in
loose/medium dense sand
Potential for noise & ground vibration
concerns, but can be solved by changing
from driving to jacking. Vibration alone
can be controlled/reduced by some
simple measures.
Installation process provides
useful feedback on subsoil
conditions & resistance or
capacity
Problem of transporting & handling of
long & large piles; prone to damages
unless adequately reinforced (>1.5%).
Can have good control over
structural integrity by larger
hammer & low drop height based
on wave theory
Inability to penetrate hard/dense strata
without driving assistance such as pre-
boring/jetting.
Reliable to have high end bearing
in strong layer based on set value
Measured capacity at or shortly after
end of driving may over or
underestimate capacity (false set).
Pile group efficiency almost always
>100% in sandy subsoils
Prone to damages during driving especially
when very hard driving is required or in
treacherous subsoil conditions.

13
Behaviour of
driven piles.
• Behaviour of driven pile can
best be understood by
continuous monitoring of
driving stresses by PDA tests.
• Why capacity of EOID >BOR?
• Excess pore water pressure
caused by initial driving is high
• Set-up capacity depending on
pile type & size, rate of blow
counts (30-120 blows/ft); soil
properties (grading, plasticity,
permeability, OCR), etc.
• False set phenonium in silty
sand or sandy silt?
• Relaxation of driven piles in
dense to very dense sand (20
to 45%)

False Set Problems & Redriving Tests (Cl.7.2.3.2 of BS 8004)
Set-up is recognized as occurring in saturated clay, and loose to medium
dense silt, sandy silt, silty sand, and fine sand [Hannigan et al., 1997].
Holloway and Beddard [1995] observed little or no set-up in very silty low-
plasticity cohesive materials. Walton and Borg [1998] indicated that set-up in
sand and gravel may not be a significant factor in long-term pile capacity.
Problems of ground heave, pile heave, false set & redriving tests must
assessed during installation of Preliminary Piles.
14
Mechanism for
False Set?
Purpose of
redriving tests?
More obvious
in saturated clay
& sandy silt or
silty sand with
fast driving?
EC 7-1 Cl. 7.6.2.7
Why MLT should
be carried out after
28 days from driving

2. Role & Responsibility of Supervisor
• Basic & main job of supervisor is to inspect, to record & to report.
• To inspect (look or view closely & critically) is aimed to ensure conformity to
specs & drgs or no defective construction. To record is aimed to establish as-
built conditions accurately for record purpose & to serve as a basis for selection
of piles for testing. To report to designer/Client if there is non-conformity or
abnormality.
• Purpose of supervision: Only sound piles complied with the design drgs &
specs are installed or to achieve zero defect construction.
• How to inspect with due care, diligence & skill? Required what basic skill &
knowledge? The main scope of this presentation is to share with you “how to
inspect & how to identify defective construction with whys”. To achieve these,
you have to learn the common driven concrete pile construction methods,
construction process & their respective construction/QC requirements plus
principles involved.
• Driven pile supervisor (especially the novice) is difficult or unable
to see/feel what is happening underground though the hammer
blows can give some degree of indications/feels or comforts about
the pile capacity. 15

Very important
• As a supervisor for piling work, your main duty is to inspect to ensure piling work is
properly carried out with particular reference to material/product quality,
workmanship & performance (integrity & capacity) of the piles as stated in
specification & shown in drawings. You have the authority to accept or reject or stop
work, but your decision must be solely based on specification and/or design drawings
or CP. Examples?
• In order to make the sound decision to accept or reject or stop work, you have to be
well-versed with the specifications, CP & design/construction drawings so as to
identify any defective material/workmanship or work procedures. In this respect, you
have to familiarize with the common terms & definitions plus construction process/
requirements related to displacement piles, good practice in piling works, common
defective works, etc.
• This presentation is aimed to tell you what are the critical construction process,
material/product quality & construction requirements related to the common
displacement piles as stipulated in MS 1314 and BS EN 12699: 2015.
• Pile designer is responsible for adequacy for pile capacity, for driving stresses, Mc
at 0.2mm/0.1mm/0.05mm crack width, pile shoe, etc. Supervisor is responsible
to ensure that the piles are cast to MS 1314 & to designer’s requirements as
shown in GDR, drgs & specifications.

Site Supervision of Displacement Piles
• Before carry out site supervision of displacement piles, the
supervisors (CRE/RE/IOWS) should understand their role &
responsibility. Peruse the duty list & seek clarifications from the
designer/Client/project manager/SRE, if necessary.
• The following info & documents are indispensable for supervisors:
Works program, Method statement, Specifications & Pile design/construction
drawings, BQ, SI report, GDR, etc. Peruse these documents thoroughly until you
understand the nature & scope of piling works to be carried out. In case of any doubt,
consult your designer/project manager or any other knowledgeable person or ask the
Contractor’s project manager for a briefing on the piling works will be carried out with
particular reference to pile termination criteria, works approval procedure, scope of
inspection & records, daily/weekly/monthly report, etc.
• Site inspection to understand the surface & subsurface conditions &
environment issues that may be affected by the piling works, etc.
• Site supervisors should be equipped with the following facilities: safety helmet
& safety boots, measuring tap, camera, blank piling record forms, site diary,
etc.

Role & Responsibility of Supervision*
a) Parties involved in conventional construction contract:
• Project Owner/client: specifies the needs of the project & provides the project fund. Project
owner also appoints project manager, Consultants & Contractors.
• Project Manager appointed by the Client: plans, manages & administers the project on
behalf of the project owner; coordinates all the parties involved in the project to ensure
successful implementation (planning, design & construction, budget/finance controls, etc. )
• Project Consultants appointed by the Client: prepare design drawings, specifications, BQ &
Contract documents. Foundation works/piling are usually supervised by C & S Consultant
who prepares the design of the foundation/piling works.
• Contractors appointed by the Client: carry out the construction works as per contract
requirements & in accordance to drawings, specifications & BQ, etc. Usually piling works are
carries out by a specialist sub-contractor.
• The Supervisors (IOWS/RE/CRE) are appointed/entrusted by the Client/Project
manager to supervise the works. Has the authority to inspect (to look closely &
critically), accept/reject or suspend the works, based on the conditions of
appointment/contract.
b) Role & Responsibility
• Basic role of pile construction supervisors is to take care of Project
owner’s interest & to perform supervision aimed to ensure piling
works are carried out by the Contractor according to
design/construction drawings & specifications.
18

Site Supervision of Displacement Driven Piles
Common displacement driven piles are:
• RC piles: common size=200mm to 400mm SQ of Qstruct=40T to 180T capacity (Qstruct
=0.25fcuAc); usual grade of concrete fcu=40-45 MPa; steel bars 1% to 2% (fy=460 MPa);
commonly driven by hydraulic hammer of Wh=2T to 16T (Wh should be around 50% to 200%
Wp), Hammer drop height should be about 300mm initially & gradually be increased to
about 1m subject driveability analysis. Pile cushion (about 75mm to 125mm)
plywood/timber should be regularly inspected & replaced after it is heavily compressed by
about 25% (loses its resilience) or when smoke comes out or chipping drops off or after
2000 hard blows. Product spec: MS 1314. Prone to damage during driving. Learn how to
estimate driving stress & permissible stress ate site.
• Prestressed Spun Piles: common size=250mm to 1m diam of Qstruct=60T to 700T. Usual grade
of concrete fcu=60 t0 80 MPa & effective stress fpe=5 to 7 MPa. Hammer requirements as RC
piles.
• Steel H Piles: common size=about 200mmx200mm to 356mmx400mm; grade 43A or 50B (BS 4360).
Qstruct=50T to 300T capacity depending on steel grade & thickness. Qstruct=0.33fy As
• Steel Pipe Piles: common size=275mm to 915mm diam of varying thickness=6mm to 25mm; 50T to
700T capacity depending on steel grade & thickness. Qstruct=0.33fy As
• Treated Timber Piles: JKR KPKR Circular 3/1975. 125mm SQ (10T) & 150mm SQ (15T). Typically 12m
long with one joint. Use as friction pile in soft to medium stiff subsoil.
• Bakau Piles: size=50mm to 100mm of about 1T capacity; typically 6m to 12m with 1 joint by steel pile
sleeve . Use as friction pile in saturated soft to medium stiff subsoil.

• Important duties for piling supervisors or IOWs are as follows;
• To check that all the piling works processes at site are carried out according to the specifications and
drawings by identifying any faulty materials, defective workmanship, non-conformity work process,
etc. (important processes for driven concrete pile installation: setting up, driving operation, hammer
drop height, any abnormalities, pile heave, penetration depth & blow counts, taking set or design
depth.
• To check that the Piling Contractor provides adequate safety precautionary measures during the course
of all the piling processes;
• To check that the Contractor follows the approved works program and method statements;
• To keep vigilance on any visual signs of pile distress on Site and in the surrounding buildings/structures
and any apparent signs of abnormal or unforeseen ground conditions.
• To report to superior/designer on faulty materials, defective workmanship, non-conformity works
process, site problems, site safety, visual signs of distress, possible abnormal or unforeseen ground
conditions, progress, quality of workmanship and adequacy of Contractor’s resources for the Works;
• To make site measurements, sampling and testing of materials for the piling works;
• To monitor the piling works of all his subordinates, if any;
• To record and ensure that all site measurements, site diaries on site field works, record drawings, in-situ
QC testing and other records are properly maintained and kept up-to-date;
• To ensure consistent supervision, site safety and measurement standard across sites under his
supervision.
• To prepare and submit weekly/monthly progress reports and any other returns as required by his
superior;
• To check and verify bills submitted by the Contractor;
• To check that the Quality Procedures are followed by all concerned subordinates;
• To check the as-built drawings/records prepared by the Contractor; and
• To check the overtime duties of all his subordinates, if any. 21

Site Supervision Planning
• Statement such as “All driven pile construction SHALL comply with all the
requirements stipulated by BS EN 12699:2015” shall be included in driven
concrete pile design/construction drawing & Specs. Why?
• Important info for planning site supervision of driven concrete pile
installation: GI/SI report (Subsoil & WT conditions, Soil types
especially localized hard/dense or abrupt localized soft/weak,
potential obstruction, etc.). GDR (pile details/geometry, numbers,
size & depth of piles, criteria of pile termination, construction
controls, etc.), Site conditions & dilapidation survey of nearby
buildings/structures/utilities/services, Contract documents (drgs,
BQ, Spec, etc.). Work program, Method statement, etc.
• Construction controls/checklist: SI adequate? Potential problems of
obstruction, need driving assistance, localized soft strata. QC
system (types & frequency of tests, measurement, inspection, etc.)
for materials (concrete pile defects, pile shoe, etc.) & workmanship
plus format of recording of works (daily activity, driving records,
testing, etc.)
• Refer BS EN 12699 for details for supervision & monitoring of
setting out, driving operation & post construction testing plus the
recording.
22

Site Supervision Planning
• Purpose of site supervision for construction of displacement piles is
basically to ensure the piling works are carried out in accordance to
CP, approved construction drgs & Specification or aimed to achieve
zero defective construction.
• As site supervisors (CRE/RE), they should be aware of their role &
responsibility.
• In order to discharge their responsibility, the site supervisors
(CRE/RE) they should carry out the supervision with due care,
diligence & due skill. To supervise with due skill means the
supervisors should possess the necessary knowledge, infor and
experience.
• What are the necessary knowledge & infor that the supervisors
should have are the focus of this presentation.
• Important Standards/references are: MS 1314: 2004 (product spec
for precast concrete piles), BS EN 12794: 2005 (precast concrete
products-Foundation piles), BS EN 12699: 2015 (Execution of special
geotechnical works-Displacement piles) 23

Quality Assurance & Construction Controls *
(cited in “Geotechnical Engineering Handbook”, Vol 3 edited by Ulrich Smoltczyk, 2003)
• Studies of foundation projects indicate that only 15% of damage or quality problems could not be
anticipated & the remainder were avoidable. The same ratio is approximately valid for pile
foundations. The main reasons for faulty quality are as follows:
a). 40% errors in design & planning (designer’s responsibility)-mainly due to inadequate &/or
unreliable SI/GI.
b). 40% poor workmanship (responsibility of Contractor & supervisor)
c). 10% material deficiencies (responsibility of Contractor & supervisor)
d). 10% other deficiencies (responsibility of Contractor & supervisor)
• How to reduce deficiencies & damage during pile installation? QMS/ISO 9000 ??
• For better control & supervision, construction procedures should be planned & construction
sequences/processes and responsibilities be clearly defined.
• Driving/jacking records, as required by CP, are part of the quality assurance.
• An essential element of quality assurance of piles is integrity testing of properly selected piles.
Frequency & criteria of selection of piles for integrity testing for driven concrete RC/spun piles &
bored piles? 1% to 2% (SS CP 4:2003)
• Principles of testing: Testing is not everything until and unless the result can be representative for the
untested ones on the safe side. Selection criteria: How to meet this requirement when select pile for
integrity and capacity tests? Why proper detail recording is an important part of QA system?
• One test is worth of a thousand of expert opinions ? 24

Site supervisor’s “tools/resources” checklist*
All supervisors for driven/jacked concrete piles shall be
equipped readily with the following tools/resources:
1.Reference materials: Full Contract documents (placed in site
office for regular reference), method statement, piling works
specifications & construction drawings with latest amendments,
if any. GI/SI Report, GDR, BS EN 12699: 2015, MS 1314-Part 3,
BS EN 12794.
2.Daily Essentials: Helmet, boots, pencil & ballpens, 5-m tape,
10m (or longer) tape, life/reflective safety jacket, HP, camera,
bubble level device, etc.
3.Blank Forms: approved driven pile log, ‘set’ records,, integrity
test, PDA & load test record forms, etc.
4.Critical & important info? Refer GI/SI report & GDR 25

Some Comments & Advice to RE/CRE*
• CRE & RE have to remember that their main job is to supervise & inspect to ensure that the piling works are
properly executed according to the drgs & specs. This means the RE & CRE have to know the specific
requirements of the particular piling work process & be able to identify defective pile construction &
unacceptable materials that are not in compliance with the specs & Drgs . Refer MS 1314 & BS EN 12699:2015.
• Nowadays, in order to achieve more cost & time saving, the pile designers and/or pile Contractors are more
inclined to adopt marginal pile design & fast/cheap construction process (low quality 3M & poor
workmanship). This means the piles constructed may not have the usual contingencies for unforeseen
eventualities & unexpected treacherous subsoil conditions. This will put the responsibility of CRE & RE to be
more stringent, demanding and challenging.
• Inspection is as good as the knowledge, experience & qualification of the CRE & RE.
• For driven piles, the CRE & RE must learn & understand the driven pile installation process (including the
purpose/principles involved) with particular reference to:
1. Pre-installation inspection,
2. Scope of inspection & monitoring during driving (hammer & drop control, pile cushion,
blow counts, jointing, pile set, etc.)
3. Recognition & identification of defective material & defective construction that will
affect pile structural integrity & capacity.
4. Abnormalities identification & mitigations. Examples?
• The CRE/RE must be more than just “look see look see at site” or just a “driven pile recorder”. The CRE/RE
should be the “eyes & ears” of Client/designer/project owner. Timely observations, suggestions & correction
advice can ultimately assure the success of the piling works. The earlier a problem or abnormality is detected
& reported, the earlier a solution or correction in procedures can be made & hence, a potentially negative
situation can be limited to manageable one. If the same problem is left unattended, the nos of piles affected
will increase, as do the cost & time of remediation & the potential for claims/disputes or project delays. Thus,
prompt detection & reporting of any problem by CRE/RE is very critical to keep the project on schedule &
within budget. 26

Some more advice for RE & CRE*
• CRE/RE should learn & should have the knowledge to identify the various
types/designs of piling rigs, hammers & pile cushion materials being used by the
Contractor.
• CRE/RE should always REMEMBER that it is NOT CRE/RE’s responsibility to direct
the Contractor’s works or techniques.
• However, CRE/RE must make reliable & accurate/unbiased records & notes as to
the piling rig & hammer on site and being used.
• If the Contractor has no proper driving assistance tools (CFA, pre-auger, casing,
jetting tools), it is important to have this info noted, as the Contractor may say the
material cannot be penetrated and was misrepresented or harder than indicated.
May not really be so if they had the proper CFA or normal auger with casing in
hard/dense water bearing strata that need driving assistance.
• The accurate, unbiased observations and documentation can serve to alleviate
problems or disputes or claims that might arise.
• The driven pile designer knows the project by heart as he/she have lived it for
probably a few years or at least several months. The Contractor knows each detail
of construction as he/she has gone through the Specs & Drgs with finger tip details
during the tender process & site visit. The CRE & RE is most probably just sent to
site at the last moment, so it is imperative that CRE/RE should be familiar with the
project (site conditions, Drgs & Specs) soonest possible so that the Method
Statement can be checked & approved fast.
• CRE/RE’s whole purpose of being sent to site is to verify that the driven piles are
properly constructed in accordance with the Specs & drags. Hence, the Specs, in
reality, outline the responsibility of CRE/RE.
27

DISPLACEMENT PILE INSTALLATION CHECKLIST
Role of R.E.
• To represent the Client & to take care of his/her interest.
• To ensure piling works in compliance with CP, Spec & Drgs.
• To record the as-built conditions accurately as specified (BS EN 12699)
• To report work progress & any non-conformity works.
• To check QA/QC plan plus site safety measures
Pre-construction controls
• Check & approve method statement
• Check installation stresses & installation acceptance criteria
• Inspect piles supplied to site are in compliance with Spec & Drgs
• List of record items & what can go wrong list plus mitigations
Check construction quality/workmanship
• Check pile position tolerance. Piling records as specified.
• Pile installation, termination & acceptance criteria. Basis?
• Basically no defective materials are used. Construction method,
procedure & workmanship/quality comply with spec, etc.
Check performance criteria/quality
• Pile tests to check capacity, settlement & structural integrity
• Test standard/spec/process, method & acceptance criteria
• Interpret test results & make decisions
28

Responsibility of supervisor for important construction processes of driven pile*
installation. What are expected from the supervisor? What are the responsibility for each construction process?
29
CONTRACTOR SET UP
PILING OPERATION
Hammer, drop height, blow
counts & pile set, etc.
PILE JOINT
PILE POSITION TOLERANCES
POST-INSTALLATION
TESTING
1. Approve method statement
2. Inspect precast con. pile to
MS 1314 & driveability anal
3. Format of piling records
4. Prelim piles
5. Termination criteria
1. Pile seting up
2. Hammer type, drop &
pile cushion
3. Blow count records
4. Pile heave, set-up
5. Redriving tests & false set
6. Abnormality?
1. Pile joint tolerance
2. Full fillet weld
3. Joint robustness &
regidity
1. Pile test procedures
2. Pile test layout
3. Pile test acceptance criteria
1. Pile position within
tolerance
2. Abnormalities

Pile Driving Flow
Chart.
Take note of the key components of
pile inspection scope & process.
RE & IOW have to study & check drgs,
spec, BQ, GDR, GI report & detail site
inspection, etc., to understand the
scope & nature of piling works before
physical supervision & inspection as
shown.
P Eng endorsement to certify the
piles supplied to site are in
compliance with the Spec & Drg
with necessary test certs, full
structural details, Mc, axial
load/BM diagram, etc,

Proper pile inspection & monitoring include for each
pile?
Remember to look closely & critically on these issues.
• Driving assistance depth (pre-auger/CFA or jetting) & hole collapse problems
• Blow count vs depth &/accumulated blow count vs. depth.
• All start & stop/disruption times & dates
• Piling sequence for big pile group; ground heave & pile heave checking
• Hammer performance observations
• Stroke/drop height changes/ fuel setting
• Hammer cushion material type & thickness (initial & final thickness)
• Pile cushion replacement criteria
• Redriving tests for pile set-up, relaxation & false set
• Pile joint & QC inspection/tests
• Installed/as-built location vs. designed location
• Pile alignment vs. alignment tolérance (no problem for round piles)
• Pile orientation vs. plan orientation
• Final pile tip elevation & cut-off elevation
• Abnormalities- unforeseen obstruction & depth, abrupt increase/decrease in blow counts,
pile deviation/rotation/tilting
• Recording as per BS EN 12699 (Cl.10: General info, particular info & additional particular
info)
32

3. Overview of Displacement Pile Installation Practice
• Piles are broadly classified as displacement piles (driven/jacked piles, driven cast
insitu piles, screwed pile) & replacement piles.
• Pile design methods: ASD (BS 8004), LRFD, Limit state design based on
characteristic values & partial factors Partial factors (EC 7-1). H. Poulos’s pile
design methods
3.1 Critical comparison between RC piles & spun piles
3.2 Principles for displacement piles
3.3 Brief history of D & C practice of pile foundation
3.4 BS EN 12699: Important terms & definitions
3.5 MS 1314 Part 1: 1993/2004 & BS EN 12794
3.6 Jacked RC/spun piles
3.7 Driveability analysis-Installation stresses
3.8 Piling specifications
33

3.1 Critical comparison between Spun piles & RC piles*
• For about same grade of concrete (1% main reinf / fep=5 MPa) & same size, Spun
piles have more even stiffness & higher crack moment resistance (Mc) vs.
bending stress, but slightly less axial capacity; lighter; spun piles have higher
resistance vs driving tensile stress.
• Spun piles have better durability. Preferred choice in marine conditions. Why?
Mc & crack width at 0.1mm/0.05mm?
• Spun piles can have supply lengths up to 15m or longer from factory.
• Spun piles have easier QC visual inspection through the hole (any cracks & joint
conditions) after installation.
• ACI-543R-12: Cl. 4.5.3.1 Reinforcement for precast concrete piles*
• Pile beam-column behaviour is determined, to a great extent, by the
reinforcement ratio. A lightly reinforced section, with approximately 0.5%, will
have approximately the same cracking and yielding moment, implying an
extremely large reduction in stiffness after cracking leading to imminent
collapse. At 1% (Ast/Ac), the yielding moment would be more than twice the
cracking moment, but the decrease in stiffness after cracking is still important.
Continue next slide.
34

3.1 Critical comparison between Spun piles & RC piles-2*
• At 1.5% longitudinal steel content, the yield moment will be 3.5 to 4
times the cracking moment and the loss of stiffness at cracking is
less important or insignificant.
• The loss of stiffness at cracking can be extremely important
especially for high-rise buildings or important structures.
• Because of this behaviour, ACI committee recommends RC piles
should have a longitudinal steel cross-sectional area not less than
1.5% nor more than 8% of the gross cross-sectional area of the piles.
If after a thorough analysis of the handling, driving, and service-
load conditions, the designers elects to use less than 1.5%
longitudinal steel, such use should be limited to only non-seismic
areas approved by structural engineers. Lateral link T5 or T6 should
be spaced not more than 150mm and should be closer at each end
of the pile. 35

*3.2 Principle &
mechanism of driving
piles.
Force transferred from hammering
> ground resistance, but < 0.85fcuAc.
F=f(Wh /Wp, H, hammer features, etc.)
R=f(soil types & strength, density, etc.)
How to control the limits of driving
stresses?
1. Wave mechanics/principles for
driving piles?
2. Purpose of hammer cushion &
pile cushion?
3. Controls of ram weight & drop
height to prevent pile damages
(T, B & C)?
4. Good pile driving practice?
5. Common malpractice in pile
driving that may cause pile
damage?
6. “Driven piles in clay—the effects of installation
and subsequent consolidation‖ by MF
Randolph, Carter & CO Wroth (1979)
36

Principles & Behaviour of Displacement Pile
37
For driven displacement piles,rapid driving by hydraulic or
diesel hammers (30-60 blows/min) can produce very high
excess pore pressure around the driven RC/spun pile in
saturated clay. In sand,silty sand or sandy silt? Consequence of
this high excess pore pressure clay?

Installation effects: stress around (a) bored pile, (b)
driven pile in clay & (c) driven pile in sand.
38

Degree of Consolidation/rate of
adhesion increase in clay

How the subsoil will react or ground movement will happen when a large
displacement is driven into cohesive soil in saturated conditions? In
soft subsoil? In stiff subsoil? In unsaturated soil? In loose & dense
subsoil? For end bearing piles, max permissible uplift<3mm. How to
measure pile heave?
40
Hagerty & Peck found good agreement between
observed pile heave & the formula below. Big pile
groups of closely spaced displacement piles in
saturated & compacted soils have serious pile heave
problems.
Hagerty & Peck, 1971

Driving piles will cause soil displacement vertically and radially. As a result, the previously
driven piles will move upward and laterally to induce tension and bending stress. Pile heave
value directly proportional to soil displacement. Therefore, as the number of driven piles
increased pile heave will increase, especially closely spaced large piles in dense soils or
saturated clay. Hagert & Peck (1971), SPM (Baligh, 1985) & SSPM Sagaseta (1988)
41

Pile Design Methods & Concepts
Effects of pile installation methods. Driving, jacking/screwing, drilling, etc., on
pile capacity & deformation characteristics cannot be calculated by the strict application of
SM principles, but with some empirical factors based on field testing. Importance to
understand the geotechnical design models/formula & parameters. Concepts of ASD & LRFD? COV of
design parameters?
STRENGTH
- GEOTECHNICAL CAPACITY
- STRUCTURAL CAPACITY &
STRENGTH AGAINST VARIOUS
LOADS & STRESSES
ANTICIPATED
MEAN
MEAN
LOADS:
- HANDLING STRESS
- INSTALLATION STRESS
- IN SERVICE STRESS
(FROM SUPERSTRUCTURE
& GROUND MOVEMENT)
ESTIMATED / TARGETTED
MARGIN (FOS)
DISTRIBUTION
FREQUENCY
FAILURE
PARAMETERS
MODEL
MEAN
MEAN
“It is generally accepted
that current methods
cannot predict failure
loads to a greater
accuracy than ± 60% of
the value determined
from a full-scale loading
test taken to failure” (M.
Tomlinson & J.
Woodward, 2008)
“We may never be able
to estimate axial pile
capacity in many soil
types more accurately
than about ± 30% “
(Randolph, 2004).

43
Probability of failure is
Still high even the calculated
FS is high If the uncertainty is
High such as limited SI.

Displacement Pile Behaviour
• False set (mainly in sandy silt or silty sand) & redriving tests. Check first few piles.
• Ground heave & pile heave. Check first few piles.
• Stress & load on pile due to ground movement from driving & surcharging?
• Driving stresses assessment by driveability analysis (slide #75)
• Design & construction for geotechnical works are inseparable. Designers &
supervisors need also to understand the underlying principles involved
1. Driven/jacked RC/spun/steel piles are the common displacement piles. Driven
cast insitu displacement piles such as Franky piles are not common nowadays in
Malaysia.
2. Working principles & mechanics of displacement piles in clay, sand & rock? D &
C principles for execution of displacement piles?
3. Design & construction for displacement pile shall include geotechnical design,
structural design & driveability analysis to show compliance with the
requirements about safety, serviceability & durability stipulated by CP (BS 8004
or EC7). Of course pile design should also include scope of design validation
(quality of materials, workmanship & performance) to ensure the requirements
of CP are actually met at site or proven through QC tests & performance
testing.
44

Common Piling Systems:
Driven/jacked RC pile/spun pile/H-
pile/timber pile, bored pile, micropile,
barrette pile, hand-dug caisson, etc.
• Each piling system has its own characteristics, pros &
cons; applications & limitations.
• Generally, driven/jacked RC piles can be quite cost-
effective for the following situations:
• Axial load generally <15,000 kN. Why?
• Ground vibration & noise are acceptable.
• No rampant pre-boring/jetting is required
• No localized obstruction
• Ground is non-aggressive or mild aggressive.

:
Remoulding, reduction of Cu & alteration of stress state
(restored slowly, about 75% after 28days)
Building up of pore water pressure (local consolidation after
dissipation of excess pore pressure may increase Cu)
Remoulding & excess pore water pressure in soft to hard clay may
cause hydraulic fracturing & negative consolidation (loss of Cu)
Very high excess pore water pressure is developed around
the pile during fast driving up to Du/sv’ = 2.0 (at pile tip Du/so’ = 3 to 4)
Pile driving in clay can cause ground heave resulting adjacent
piles to upheave. Maximum pile heave can be 0.2 – 0.3 times of
measured ground heave. Redriving or tapping is necessary for end
bearing piles especially when pile heave >3mm.
When piles are driven into loose sand, densifying effect will
cause great increase in friction (may be reverse case for dense sand)
Driving effect & redriving test in sandy silt & false set?
DISPLACEMENT PILES – Behaviour & effects-1

Ground vibration especially by impact percussion methods can
cause damages & settlement to the nearby structures. Dilapidation
survey. Case histories. Mitigations?
Soil/ground movements such as ground heave in cohesive soil
or ground subsidence of loose sandy soil, lateral soil movement, etc.
Precise levelling < 3mm permissible. Why?
Noise & air pollution for piles installed by driving may not be
acceptable in built-up areas.
What can go wrong? Excess pore pressure & soil movement may
damage the pile & adjacent piles (induce extra tensile force causing
tensile crack, joint separation, lift off base of adjacent piles, etc.).
Nearby buildings or structures or buried utilities may also be
damaged. For soft ground, piles can be damaged by excessive
driving tensile stress especially at instant when the pile is driven
through dense layer into weak underlying soil. Excessive driving
compressive stress also can be encountered when pile head MS
plate is defective or hammer is not squarely striking the pile or pile
tilts (common when stiffness of subsoil is very erratic or inconsistent
(boulders or localised lenses of dense sands), or presence of inclined
bedrock or pinnacles, etc.). Mitigations?
DISPLACEMENT PILES – Behaviour & effects-2

3.3 Brief History of D & C Practice of Piles
• Displacement piles: scope of design verification according to
CP2004: 1972 & BS 8004: 1986?
• JKR standard RC piles (cast at site) were commonly used before
1986. After 1986, JKR piles are slowly replaced by precast concrete
piles by factory cast piles based on BS 8004: 1986.
• Bakau piles (JKR practice & spec),
• Timber piles (JKR Spec & MS ).
• Common hammer types & calculations of set value
• JKR Standard RC pile (Drg HQS/STD/101/1A dated 050480)
• JKR Circular about accreditation of precast concrete piles (1991)
• JKR D & C practice for foundations of low-rise buildings
• JKR D & C practice for foundations in limestone formation
• JKR D & C practice for foundations in soft ground
• JKR D & C practice for foundations in fill ground 48

3.3. Brief History-Past & Present Piling Practice-1*
Past (before 80’) Present (after 00’)
Code of
Practice
CP 2004:1972 by BSI. BS 8004:1986 by BSI.
Major changes?
Major changes
from CP 2004
to BS 8006
Total 10 Clauses. Pile
Foundation design is
elaborated in Clause 7, which
has 6 sub-clauses. Cl 7.6 is about
Safety Precautions including site
supervision (changed to Cl 11 in BS
8006)
Same format & 11 Clauses. Pile
Foundation design is elaborated in
Clause 7, which has 6 sub-clauses
as CP2004, but sub-clause 7.6 is
replaced by new item on integrity
testing of cast in-place piles.
Structural
design
Shall have adequate structural
strength to undertake various
stresses due to handling,
installation & in service.
CP114:1967. Lateral Reinf of min
6mm diam & >0.6% gross vol. for
3B from pile ends. Recommend
grade 25 & 20 concrete for hard to
v hard & normal/easy driving
respectively, with min cement
content = 400 to 300 kg/m3
Shall have adequate structural strength
to undertake various stresses due to
handling, installation & in service. BS
8110:1985/CP116. Lateral Reinf >0.6%
gross vol. for 3B from pile ends.
Recommend grade 40 & 25 concrete for
hard to V hard & normal/easy driving
respectively, with min cement
content=400 to 300kg/m3.
Concrete cover Cl 7.4.2.3.2: not less than 40mm or
50mm if sea water or other
corrosive influences
Cl 7.4.2.3.2: not less than 25mm (mild) to
50mm (very severe/aggressive ground)-
Table 3.3 of BS 8110
Pile Testing
methods
MLT or CRP MLT & CRP, but PDA, Statnamic &
Bidirectional load tests are also used.

3.3 Brief History-Past & Present Piling Practice-2
Past (before 80’) Present (after 00’)
Code of
Practice
CP4/CP 2004:1972. BS 8004:1986/EC 7.
Major changes?
Common Pile
Types
JKR Practice & Spec. High
social status for Engineers.
Driven bakau/timber for low-
rise buildings. RC/Spun/Steel
Rail/H & pipe/ Franky piles.
Bored piles & micropiles not so
common. Small jacked-in piles.
Case histories?
Driven or jacked RC & Spun piles
up to 300T are common. Bored
piles up to 3m diameter & grade 60
concrete & micropiles up to 300mm
diameter with design load=150T.
Case histories?
Hammers Diesel/drop/steam hammers.
Weights & efficiency? Costs?
Hydraulic hammers & ram wt=1T to
9T are common. Efficiency>65%
RC Piles JKR std design: 8”, 12” & 15”. Cast
at site grade 25.5 concrete with
2.1% to 3.7% main reinf. Design
capacity=25T, 45T & 65T. AS2159:
1978 required 1.25 to 2%.
Factory cast to MS 1314 using grade 45
to 80 concrete with about 0.8 to1.2%
steel. Sizes: 200mm to 450mm with
design capacity 45T to 220T.
Pile types for
limestone
areas
Driven H piles by drop hammer.
Driven/jacked RC piles occasionally used,
but with15 to 25% damages even drop
hammer was used. Discount pile capacity
15 t0 25%. JKR Guidelines.
Micropiles & bored piles. Driven or jacked
RC/Spun piles by hydraulic hammers are also
commonly used. JKR Guidelines are used.
Discount pile capacity by 15 to 25%. Case
histories?

D & C Requirements stipulated by BS 8004: 1986
 Refer to Clause 7 (Pile Foundations) with 6 sub-clauses as follows:
 Cl 7.1-General
 Cl 7.2-Preliminary investigation
 Cl 7.3-Design considerations (General, Choice of type, Strength of piles,
Piles in groups, Ground conditions, Negative friction, Pile caps &
Factor of safety).
 Cl.7.4-Types of piles (Timber piles, Precast RC piles (General, Materials,
Design, Manufacture/curing transport & storage, Driving
procedure, Stripping pile head & Lengthening piles), Prestressed
concrete piles, Driven cast-in-place piles, Bored cast-in-place piles
& Steel bearing piles)
 Cl 7.5-Bearing capacity & test loading
 Cl 7.6-Integrity testing of cast-in-place piles
About 45 pile design & construction issues/requirements/considerations
are mentioned in the sub-clauses. Pile designers should be aware &
understand the implications (underlying requirements/principles) &
significance of each sub-clause. The requirements related to pile capacity
& settlement plus structural design should require detail analysis &
calculations to show compliance with? Subjects commonly overlooked?

Displacement piles - Golden Rules
• Select pile type & installation method based on environmental factors, subsoil
conditions & loading., etc. Proper selection requires experience or refer reported
case histories. Refer Prof J Burland’s advice.
• Prefer small group of large & long piles than big group of small & short piles (Cl. 7.1
of BS 8004). Groups of 2-5 piles are cost-effective. Be aware of limitations &
problems of small piles (<200mm). Why?
• Driven concrete piles are usually more cost-effective & fast especially for low to
medium loaded structures (<1000T) if driveability & environmental factors (ground
vibration & noise) are acceptable. Prone to damages by installation especially when
hard driving is required or slenderness ratio >100 , in/near unstable slope/ground,
localized boulders/obstructions? Must check installation stresses (Refer Table 3).
WCGW for displacement piles? For displacement piles, always assess ground
movement effects to the nearby buildings/structures & buried utilities.
• Spun piles are preferred in aggressive ground. Why? Compare Adv & disadv of RC piles & spun
piles.
• When bored piles are preferred? When driven steel piles are preferred?
• Very important to understand the fundamental engineering principles involved in D &
C of piles and various pile behaviours installed by different methods in different
subsoil conditions (clay, sand, IGM & rock) when subject to different loading and
ground movement. Increase pile stiffness by using rake piles or ground treatment.
52

What are the factors for Cost-efficient Driven Pile Design.
Pile design can only be optimized when more adequate & certain/reliable info are
made available
• Pile type/section/material: Optimizing the pile type, section or material based on desired
allowable loads & subsurface conditions.
• Testing: Either using pre-construction testing to better model subsurface conditions or
construction testing (PDA, SLT) to reduce uncertainties.
• Set-up: Incorporating set-up into the design can reduce the pile length, section and/or pile
driving equipment. Use of grade 80 to 90 concrete!
• Higher allowable loads and/or allowable design stresses: Reduce the pile count and pile cap
size by fully utilizing the available geotechnical & structural allowable load for each pile
• Driving Criteria: Incorporate test results and develop installation criteria using more reliable
methods such as WEAP vs simple dynamic formula.
• To enable to carry out practical/cost-effective design or cost-efficient design, the designers
should be well-versed about various issues about pile design & site/subsoil specific info. What
are the important issues about pile design that the designers should learn & be well-versed?
Applications, advantages & limitations of various pile types. Principles & SM theories about
how pile behaves in various types of subsoils installed by various methods. Methods &
models used to estimate fsu & fbu plus the principles involved. Risks & uncertainties for
various types of piling & the usual mitigations. Design requirements stipulated by CP (BS
8004/EC7) for safety, serviceability & durability? Scope of design
verifications/analysis/calculations to show compliance with the design requirements. Scope of
design validation to ensure quality, workmanship & performance for the pile design. Scope of
SI to get the necessary infor for pile design, etc. 53

3.4 BS EN 12699: 2015
• Normative references: BS EN 12699; BS 8004: 1986; MS
1314/BS EN12794
• Important terms & definitions:
displacement piles; prefabricated (displacement) piles;
cast-in place (displacement) piles; jacked piles; casing;
liner/lining; pile joint; pile shoe; impact hammer; helmet;
pile cushion; follower; driving; driven pile; driving
assistance; restrike; initial piles; test piles; trial piles;
preliminary piles; driving criteria; monitoring; supervision;
recording; MLT; CRP pile test; dynamic pile load test; low
strain integrity test; heave & redriving test (EC 7-1, Cl.
7.6.2.7)
54

Summary of important contents of BS EN 12699
1. Scope: Establishes the principles & construction requirements for displacement piles.
2. Normative references: Relevant Standards/CP referred.
3. Terms & definitions: Define important terms for displacement piles.
4. Information needed: Spell out the crucial info required to be known to assess the impacts
involved before commencement of piling works.
5. Site Investigation: Stipulates important info sought from SI report.
6. Materials & products: Specifies basic quality requirements for materials & products for
various types of displacement piles. For precast concrete piles, refer BS EN 12794 or MS 1314
for precast concrete pile specification.
7. Design related considerations: Stipulates the D & C of geotechnical & structural
requirements for various types of displacement piles that site supervisors shall know &
understand.
8. Execution: Stipulates construction requirements for procedures, equipment, QC, etc.
9. Supervision, monitoring & testing: Stipulates the active & passive role & scope of checking
technical quality of piling works
10. Records: Specify “what to record” to establish as-built conditions.
11. Specific requirements: Works Spec & statutory requirements related to site
security, operation safety of piling works; environment issues (noise, vibration & air
pollution) & impacts/safety of the surrounding structures, buildings & services.
55

What are the important Terms & Definitions for Displacement Piles
commonly misunderstood? Principles involved?
• Prefabricated (displacement) pile, big/small displacement piles
• Cast in place (displacement) pile
• Screw pile, jacked pile, driven pile, grouted pile
• Initial pile, preliminary pile, trial pile, test pile, instrumented test pile
• Helmet, hammer cushion, pile cushion, packing
• Driving assistance
• Driving criteria
• Hard driving, driving to refusal, set, redriving test & false set
• Static load test (MLT & CRP), dynamic pile load test, sonic test, low strain integrity
test, rapid pile load test (statnamic pile load test)
• Pile heave, ground heave
• Monitoring & supervision
• Records
56

What info needed before commencement of piling works
1. Any info relevant to the execution of the piling works SHALL be provided/
acquired, especially the info that have impacts on the piling works.
2. The following minimum info should be considered & made available before
commencement of piling works for necessary assessment & evaluation:
• SI report
• Construction Drgs & GDR
• Spec & contract document
• Project site: Boundaries, previous land use, contour plan, platform level, TBM
• Site inspection: project site conditions, site access, slopes & nearby buildings/
structures/utilities (buried & overhead). Affected by the piling works?
• Environment restriction on noise level, ground vibration degree, local authority
restriction (piling time restriction), etc.
• Any concurrent construction activity/project nearby?
3. Need dilapidation survey?
4. Need any trial pile or continuous PDA monitoring driving stress to check
suitability of construction method? For erratic subsoil conditions especially with
presence of localized obstruction or soft strata, trial piles should be carried out.
5. Any previous comparable reported case histories?
57

What info sought from SI report
SI report and SI results with particular reference to critical information as listed below:
• Subsoil profile & levels of hard layer/bedrock; extent, inclination & properties of
bedrock (type, TCR, RQD, open or filled rock joints/discontinuities & UCS)
• Piezometric levels of groundwater and its variations. Aggressiveness of subsoil
and/or groundwater? Any contaminated soil/waste?
• Any localized hard obstruction that may need driving assistance (preboring)?
• Displacement piles will densify loose/medium dense sand to dense/very dense sand
especially big pile groups.
• For limestone formation, any very loose or very soft materials above bedrock that
are likely to flow significantly away to connected channels causing ground
subsidence or sinkholes to happen?. Other treacherous features such as pinnacles,
inclined bedrock, floaters, overhung rock, etc., that may cause displacement piles to
deflect or rotate?
• The above issues & problems should be adequately evaluated/interpreted/
assessed and understood by the site supervisors to make sure necessary
mitigations have been duly provided by the Specifications or the designer or the
contractor. Consult designer & specialists, if necessary.
58

Materials & Products for Displacement Piles
1. All materials & products for displacement piles SHALL comply with relevant
Standards & product Spec as specified. The source of supply & factory test certs
shall be verified & documented
2. Prefabricated/precast concrete piles shall be manufactured by ISO certified
factory & comply with MS 1314 & design Drgs with respect to concrete quality,
requirements for dimensional tolerances, minimum reinforcement, pile joint &
pile shoe. Factory visit & quality checklist as per MS 1314 shall be carried out &
documented. Visual inspection for any pile defects plus necessary rebound
hammer tests shall be carried out for all piles sent to site & before driving. Other
requirements for storage, handling & installation as per spec shall be complied
with at site.
3. Prefabricated steel pipe or H piles if used shall also be verified to ensure
compliance with Standards & Spec.
4. For precast concrete piles, coring & subsequent compression tests shall be
carried out if the results of rebound hammer tests and/or results of visual
inspection are not satisfactory. Bending test may also be ordered to verify
workmanship and crack moment.
5. Any materials that do not comply with the specified requirements shall be
removed from the Site immediately or as soon as possible.
59

Design related considerations
1. Site supervisors shall know & understand the pile design related considerations
especially pile material & structural requirements, geometrical dimensional
tolerances & pile behaviour during installation & in working condition. Pile
driving in clay/sand/rock, hard driving, driving to refusal or to length, pile heave
& movement, directional stability, driveability analysis, pile capacity (geo &
structural), etc.
2. Adequacy of scope of SI? Adequate & reliable? BEM Circular 5/2004.
3. Needs for driving resistance? The influence of driving assistance methods on the
performance of the piles & safety of existing structures & slope if any.
Details/measures to ensure performance?
4. Design for impact driving: driveability analysis to ensure no overdriving.
Methods: WEAP? Broms method?
5. Design related to pile joint & pile shoe. Design criteria? Defects?
6. Design of big pile groups (>5 piles): Spacing & permissible pile heave. How to
check pile heave/displacement? Driving sequence?
7. Purpose & principle of redriving test & false set.
8. Ground vibration & noise level issues & how to check to ensure compliance with
local authority requirements?
. 60

EXECUTION for Displacement Piles at Site
1. Check method statement (MS) prepared by piling Contractor to ensure
adequacy & in compliance with the design & Spec. Piling rigs, adequate &
appropriate? Hammer type & capacity adequate & appropriate? Type of pile
cushion & frequency of replacement appropriate? Quality assurance plan?
2. Site preparation: Check to ensure the ground is stable for the piling rig & piling
works and materials are orderly & neatly stored & arranged.
3. Before piling work is commenced, make sure reasonable precautions and
measures are taken after inspection of the site & the surrounding. If need be,
noise level & ground vibration and other precautions (pile/ground heave &
redriving tests, etc.) should be checked in the early stage of piling works.
4. During the driving or jacking, make sure all the relevant details are recorded,
especially any abnormality, which is very important for quality assurance
requirements.
5. Items & details to be checked (checklist) should be prepared & implemented at
site. Visual inspection on piles for defect, pile verticality, welding, blow counts
changes drastically, pile deflection/rotation/titling, taking set, driving
assistance method, ground movement/creeping, etc., are of particular
importance.
61

Supervision, Monitoring & Testing
1. The site supervisors shall be aware of his/her role & responsibility and shall be
well-versed with the approved method statement (MS), SI report, construction
Drgs & Spec to ensure the piling works are properly carried out.
2. The site supervisor shall exercise with due care, due diligence & due skill when
performing his/her duty to supervise the piling works.
3. The site supervisor shall be well-versed in the specific material quality
requirements, construction requirements for the piling procedures to ensure
only sound piles are installed for the necessary structural integrity and pile
capacity.
4. The site supervisor shall inspect with due care/diligence/skill to identify any
defective construction/piling, that are not in compliance with the Spec & Drgs.
All non-conformance shall be reported to designer/Client.
5. Visual inspection & adequate/relevant QC tests & performance tests shall be
carried out to validate the required quality/performance. Refer MS 1314 & BS
EN 12699: 2015 or established guidelines. Consult the designer/specialist, if
doubt is encountered.
62

Records
1. Piling records with relevant details as stipulated by Cl. 10 of BS EN12699 shall
be established for QC evaluation, basis for subsequent selection of piles for
tests, for quantity preparation for payment, etc.
2. For precast concrete piles supplied by ISO factory, specific certified details such
as batch reference, date cast, grade of concrete & reinforcement in drg, QC test
results/certificated & other details as specified by MS 1314 shall be furnished
by the ISO factory. The details & date of delivery to site with delivery note/cert
shall be checked & documented for future reference.
3. Piling records including pile point reference (as shown on construction Drg),
date & time of driving, redriving & interruption, jointing, hammer type/Ram
weight/drop, blow counts, type of pile cushion & time of replacement, set
value, checking of pile position & verticality, pile heave checking (for big pile
group), results of redriving tests, observed abnormality, etc., shall be recorded
according to the approved format before commencement of piling works.
4. Photos showing pile conditions before driving pile shaft/end plate/shoe, etc.),
pile jointing/welding, checking verticality, taking set, ground heave/settlement,
etc., shall also be captured for records.
5. All piling records shall be checked & verified for adequacy and endorsed by
IOW & contractor.
63

Specific Requirements
1. Client & local authority’s statutory requirements shall be checked
to ensure compliance with at site with particular reference to:
• Security of the site
• All workers are trained/experienced; no illegal workers.
• Operation safety of driving & auxiliary equipment & tools,
• Safety of the working practices
• Noise level & ground vibration problems & permissible limits?
• No impact hammers; only jacked piles & replacement piles are
allowed in DBKL or other sensitive areas?
• Impacts on surrounding structures, utility & slopes, etc., due to
piling works.
2. Special requirements such as “only jacked piles & replacement
piles are allowed” (DBKL); No bakau piles (JKR); Only specific piles
are allowed, etc.
3. Environment damages, etc.
64

CP requirements for D & C of displacement piles (BS8004/EC7)
• Durability requirements: design life >75 yrs (EC7: 50-120 yrs). Refer Clause 10 of BS
8004 for design requirements for concrete/steel/timber piles.
• Environment requirements: Level of ground vibration & noise tolerable by nearby
existing structures/utilities & people? How to measure? Refer Slides 82-87
• No global equilibrium problem or no global instability/failure of pile foundation as
the result of expected/known/existed site conditions. Unstable slope/ground?
• Structural requirements: adequate structural strength to withstand various types
of stress/loads during handling, installation & in service. Loads due to ground
movement if any can be disastrous.
• Geotechnical requirements: adequate & reliable SI. FOS against pile geotechnical
bearing failure due to various types of loads > 2 to 3. Pile settlement/deformation
is tolerable by the structure.
• Misc requirements: Be aware the potential risks & uncertainties. Design adequate
mitigations vs WCGW at site during construction & in service. Examples?
• Prerequisites to be well-versed in pile design?
• BS EN 12699:2001 “Execution of special geotechnical works-Displacement piles”
65

Piling in Marine or off-shore Conditions
• Generally piling in off-shore is comparatively more difficult, more
complex & more risky when compared with that in onshore. How
& why?
• Piling for off-shore structures (jetties/bridges/ports/offshore
platform, etc.) has to design for high lateral load capacity &
aggressive/severe environments. Usually large diameter spun piles
or treated steel pipe piles are used & preferred. Why? Piles are
usually not fully embedded in seabed conditions & usually have
weak or difficult subsoil conditions.
• Common required mitigations vs difficult conditions are pile
position & alignment are difficult to control, directional stability
issues, aggressive & durability problems, high lateral loads, high
driving tensile & bending stresses, etc. How & why?
• Pile testing: extent, methods, purposes, etc.
• Design guides: API design standard is preferred. Why?
• Case histories of design & construction?
66

3.5 MS 1314 & BS EN 12794
• MS 1314-Part 1: General requirements; Part 2: Bending strength test;
Part 3: Precast RC piles (class M/J/S)-1.2/1/0.8% Gr45 (min): Part 4: Precast
pretensioned spun piles (class A/B/C); Part 5: Precast prestressed
concrete square piles; Part 6: Small RC square piles (RCS-1 & RCS-2) &
Part 7: Guidelines to the installation & load testing
1.Significance of dimensional tolerances: Length±25mm;
cross section dimension; Straightness; Squareness of pile
head ±5mm. (Why advanced countries seldom use concrete piles > 1 joint?)
2. Materials: Cement, Aggregates (fine & coarse), admixtures
3. Manufacture: Supervision; Manufacture detail; Concrete; Mould; Rebar; Joint; Shoe; Curing;
Handling (lifting from mould/storage/transportation/pitching & driving). Common malpractice?
4. Bending Strength Test: Purpose & significant?
5. Marking: Manufacturer’s trade name/logo; Pile designation;
Date of casting & Pile reference. Significance? Serious problems of grade 80
RC concrete piles?
67

BS EN 12794: 2005- Precast concrete products-Foundation piles
1. Scope: Product spec for precast concrete pile
2. Normative references: EC 2; EC 7-1 & EN 13369
3. Terms & definitions; segmental piles; pile top; pile head; pile shaft; pile
toe; pile bottom; pile joint; pile shoe, etc.
4. Requirements: Materials; Production; Finished product (Geometrical
tolerances for joints, shoes, mechanical resistance; durability, etc.)
5. Test methods (Concrete; Measuring dimensions; Weight; Verification
tests for robustness & rigidity of pile joint)
6. Evaluation of conformity (Finished products)
7. Marking
8. Technical documentation & retrieval system
Main differences between MS 1314 & BS EN 12794?
Bending tests of MS 1314 are to check crack moment & pile joint
workmanship before driving while bending tests of BS EN 12794 are to
check robustness & rigidity of pile joint (welded or mechanical joint) after
driving.
68

Product spec: MS1314-Part 3- RC Piles (2004)
• Minimum structural requirements (Reinforcements, cover, Mc,
concrete grade, shoes, dimension tolerances, etc.).
• QC requirements (materials, product, workmanship, dimension
tolerances, bending tests, etc.)
• Spec verification by factory visit, catalogue & records.
Problems of precast concrete piles (RC, Prestressed spun-Part 4)
• Adequate structural capacity for handling, driving & soil movements,
etc. Very critical & uncertain for problematic sites. Shall have more
contingencies! No bold design! Why?.
• Dimension (chamfered corners, joints). Important?
Marking & certification
Why marking is important? Piles without marking to MS 1314 should be
rejected. Why?
Small Precast RC Pile (<200mm) problems?
BS8004, ASTM recommendations. Limited applications. Why?
Mc, cover & reinforcement- Big problems by little errors!
Dr. Ting WH’s evaluation (IEM Bulletin May 87 issue)
Case histories 69
PRECAST CONCRETE PILE

3.6 Jacked RC/spun piles-1
• Jacked piles are also displacement piles without ground
vibration problems, but ground displacement is the same as driven piles.
• Installation stresses depends on method of jacking. For hard
jacking fb should be checked by Broms method. Termination
criteria: F=2 to 2.5WL; d=3 to 10mm; t=10 sec to 10 minutes; F= minimum 2 cycles
with time lapse T=1 to 10 minutes.
• AS 2159: 2009-Max jack force F=2WL/K, where K is determined
from SLT, but not <0.97. In the absence of SLT, K=0.90 for pile
length >15m, K=0.77 for pile length=8m to 15m & K=0.61 if pile
length <8m. Basis? F >5 cycles. F maintained not < 15 sec. T not <
2 minutes.
• Singapore (GeoSS, 2015)- Max jack force F=2 to 2.5WL until set
displacement d < 10mm with holding time t=30 sec.
• Hong Kong (Li & Lam, 2011) -Max jack force F=2.1 to 2.5WL until
set displacement d < 5mm with holding time t=15 minutes.
70

Jacked Piles-2
1. Jacked piles are environmentally-friendly & have been used in Malaysia since early
70’.
2. Max. jack force up to about 700T has been used with machine width of about 14m &
clearance for jacking up to about 7m (centre jacking).
3. Pros: Low noise & negligible ground vibration (vs. driven piles). High Qu/W & low
COV (vs. bored piles). Faster construction (vs. bored piling) & cleaner site (vs. bored
piling).
4. Cons: Required larger, strong & flat piling platform. Slow construction (vs. driven
piles). Limited jack force (about 700T). Can’t jacked through intermittent hard strata
(vs. bored piles). Soft ground problems.
5. Comparison between jacked piles & driven piles
71
Jacked Piles Driven Piles
Cyclic load during
installation
Less cyclic load cycles.
2 times higher base stiffness.
More dynamic cyclic load
cycles
Termination criteria By set/penetration value
using jack/static force; not
reliable if creep problems
exist. Factors affects criteria?
By set for end bearing piles. By
depth for friction piles.
Complex dynamic loading
wave theories.
Problems & uncertainty in
load transfer during
installation
Hydraulic systems & jacks
require regular calibration.
Clip system.
Hammer efficiency. Need
WEAP to control weight &
drop. Improper cushions &
eccentric hammering may
cause pile damage.
Pile damage during
installation
Low High, but can be controlled by
proper driveability analysis to
control fc & ft & Broms method to
control fb.

Jacked Piles-3
1. Rankine Lecture by Prof. Mark Randolph (2003):
• Bored piles-Zero residual pressures at base & end bearing can only be mobilized at large
displacement, especially when the risk of soft toe is high.
• Driven/jacked piles have high residual pressures locked at the base of the piles during
installation (vs. bored piles). Hence, higher end bearing can be mobilized at smaller
displacement (vs. bored piles).
2. Also, Mandolini, et al (2010) reports that driven/jacked piles give high Qu/W (=73) & less
influenced by construction method (COV of Qu/W=0.08) when compared with bored piles with
Qu/W=12 & COV (Qu/W)=0.28.
3. Termination criteria:
• Max. jack force (F)? Usually F=2 to 2.5 WL. Make sure < Ultimate structural capacity.
• Set displacement (d) <3 to 10 mm with minimum holding time (t)=10 sec to 10min.
• Minimum numbers of cycles (f)=2 to 5.
• Time lapse between cycles not less than (T)=1 to 10 minutes.
• Criteria for F, d, t, f & T for end bearing piles & frictional piles or in sand/clay?
• Example 1: All piles shall be jacked to F=2.3WL with minimum f=2 cycles until set d <
10mm or max L=24m with holding time t=5 seconds. Time lapse between cycles T=5
minutes.
• Example 2: All piles shall be jacked to F=2.3WL with minimum f=2 cycles until set d
< 5 mm or max L=24m with holding time t=5 seconds. Time lapse between cycles T=2
minutes.
• Example 3: All pile shall be jacked to F=2.5WL with minimum f=3 cycles until set d=1mm
with holding time t=15 seconds. Time lapse between cycles T=1 minutes. End bearing
piles?
4. Factors affecting the above 4 criteria? Principles involved?
72

Comparison of Driven & Jacked RC/Spun Piles
Driven Piles Jacked Piles
Ground vibration High Negligible
Noise High Low
Rate of Installation Fast Slow, especially in soft ground
Penetration-ability High Low
Prediction of capacity Quite reliable for end bearing piles
by set value
Quite reliable by jacking force
Pile damage during
installation
Prone to be damaged by driving
stress due to tension if presence of
underlying localized soft/weak
strata & bending as the result of
hard driving & too slender, etc.
Prone to be damaged by bending
due to uneven localized hard
material at pile toe and/or too
slender, etc.
Mitigations Vs. Problems
(Wh=Weight of hammer
Wp=Weight of pile)
Wh should be high or >Wp. Drop
height should be around 300mm
initially & gradually increased to
<1m. Pile cushion should be
replaced when burnt.
Jacking force should be
maintained as long as possible &
repeat few times to improve
penetration/end bearing

3.7 Driveability analysis
• Purpose: Based on SI results (clay, silt, sand, IGM) & the
proposed hammer type, ram weight & drop, assess whether
the pile can be driven to the required design depth to achieve
the required capacity without pile damages (Cl 7.3.3.2 “ It is
part of the design process to consider the stresses which may arise
during the installation ….”).
• Need driving assistance? Driven to set/refusal?
• Driveability analysis is aimed to ensure the displacement piles can be
installed to the design depth without overstressing (the installation
stresses exceeding the permissible limits).
• Methods: Pile Driving Formula, WEAP & Broms method
• Installation/driving stresses: fc, ft & fb shall be checked to prevent
overdriving for driven concrete piles by WEAP or Broms method.
• Broms method : fc = 3h½, ft = 10% - 30% fc, fb = 20% - 50%fc or Qd <
Mc/0.15d, where Mc is based on crack width = 0.2mm to 0.05mm (BS
8004). Estimated installation stress shall be checked with permissible
stress.
• Miscellaneous : Handling stresses (1/8 WL x 150%) & structural capacity
discount for slenderness ratio (l/d – 100)% & joints 5n%. How to check the
handling stresses are not exceeding the permissible limits? 74

Driveability Analysis *
(Permissible Dynamic Pile Driving Stresses (AASHTO/AS 2159/PDI)
Pile Type Permissible compressive
stress, fca
Permissible tensile stress
Precast RC 0.85fcu
(EC 7-1, fca=0.8fcu)
0.7fyAs/Ac or 0.1fcu or
0.8fcu0.5 , whichever is
lowest.
Precast
Prestressed
0.85fcu-fep fep+0.25fcu0.5
Steel 0.9fy 0.9fy
Timber 3Sa 3Sa
75
Driving compressive stress, fc=3h
0.5
, driving tensile stress, ft=0.1 to 0.3fc,
driving bending stress=0.2 to 0.5fc ( BB Broms) h=drop of hammer in cm.
For very hard driving, design working pile load Qw shall be limited
to Qw< Mc/0.15B, where MC is crack moment & B is pile size.
For aggressive ground, Mc shall be based on crack
width<0.1mm. Why RC piles are not suitable in aggressive
ground??

L
M = 1.5WL/8
M = WL/12
One
point
lifting
h
Hammer
Compressive
Bending stress
Compressive
Tensile
stress
Drop
Handling stress
Check adequate rebars & concrete
strength for bending moment due to
lifting from casting moulds
(1.5WL/32) & one point lifting at
site (1.5WL/8).
Make sure the stresses are within
the permissible limits. Refer Fig 7.
Installation Stress
(WEAP/Broms method)
Compressive stress,
fc = 3h1/2
Tensile stress,
ft = 10 – 30 % fc
Bending stress, fb=0.2-0.5fc ?
Refer Note 3
Working Stress
Permissible axial stress for R.C. piles & steel piles
is 1/4fcu and 1/3fy respectively.
Check lateral load capacity & moment resistance
(use Broms Method & PIGLET for load
distribution). For newly filled ground, long term
ground movement & collapse settlement due to
wetting by infiltration or capillary action from
inundated toe may cause creeping & negative
friction & extra bending stress.
Notes:
1. Estimation of axial load capacity based on static formula and SI results is only part of the geotechnical design scope, after a specific pile
type & size is selected.
2. The structural capacity (Qstr) for the suitable pile type & size shall be checked for adequacy for handling, installation & working
stresses.
3. Extra stresses caused by workmanship imperfection or allowable dimension tolerances shall be assessed. Max. Qstr shall be discounted
for joints (5n %) & slenderness ratio (l/d – 120) %, where n = number of joints, l = pile length & d = pile size. To control cracking, Qstr
shall be less than Mc/0.15d, where Mc is the crack moment based on crack width  0.2mm in normal condition or  0.1mm in aggressive
ground. For permissible installation stress, refer Table 7.
Figure 8: Scope of Structural Design for Driven Piles (Loads in piles)
Bending
stress
Active
force
Lateral
load
Negative
friction
Ground
deformation
76

3.8 Piling Specifications
• Site supervisors should be well-versed with Spec & addendum
or supplementary Spec for piling works.
• Spec only tells supervisors to do this to do that. Site
supervisors especially CRE/RE should learn the
procedures on how to do this to do that as specified,
including understanding of the basis and the
underlying principles involved. In case of doubt,
supervisors should immediately consult the
designers or any other experienced engineers.
• Scope of Piling Spec for Displacement Piles (4 parts)
• 1. General: Scope of works; site visit; SI report; Piling resources; supervision;
Progress report; Program; Records & as-built Drgs; Adjacent structures/services;
method statement; Reference station; Setting up; Tidy site; Tolerances; Rejection
of piles; Nuisance & damage; Alternative piling system by contractor, etc.
• 2. Materials requirements (RC piles & spun piles to MS 1314,
steel H , Steep pipe piles & timber piles)
• 3. Construction requirements. BS EN 12699 & BS EN 12794
• 4. Post-construction testing/Design validation/pile tests 77

Piling Specifications-2
• For concrete piles using grade >50 , PEng endorsement that
the piles are grade 50/60/80 pile is important. Bending
test to MS 1314 should be carried out at site on welded
joint to verify workmanship & to show that the bending
capacity at the pile joint is greater than the bending
capacity of the pile body. Permissible crack width shall be
0.1mm unless otherwise specified in the drawing and the
subsoil is tested and approved by the Engineer/SO to be
non-aggressive, in which case the crack width can be up to
0.2mm.
• Supervisors should be aware of the scope of inspection
&to make sure the concrete piles are cast in compliance
with MS 1314 & Spec before allowing to be installed.
Common piling abnormalities?
78

4. Common Problems for Displacement Pile Installation
• Main advantages for driven & jacked concrete piles are the
structural requirements for handling & installation can be
assessed & pre-installation defects can be inspected/ tested.
• However, the major problems of driven/jacked concrete piles
are the structural damages during the installation as the results
of mainly inadequate/unreliable SI, misinterpretation of SI
results or ignorance/inadequate assessment of structural
requirements of soil-structure interaction.
• Site supervisors should learn to recognize the significance of
pre-installation inspection & be aware of the common
construction piling problems in soft ground, limestone
formation, filled ground & typical problems in residual soils of
granite & meta-sedimentary rocks.
• Problems of grade 80 or 90 RC piles & small piles (<200mm)?
79

Variable subsoil conditions in strength & WT. Ground is full of surprises & risks to
the unwary. Aim of SI is only to reduce the risks ALARP. SI is not everything in geo
design, but without SI geo design has no basis. Why SI is important for pile design?
SI is an important part of geotechnical design. Why?
SI including sampling, field & lab testing provides basis for optimal geotechnical
design. Geo design must be based on CP/design guides, SI results & reported
case histories.
SI  soil/material properties  ground characterisation  prediction/modeling
(design)  QC/QA tests to verify important design assumptions & performance
criteria.
SI Practice:- EC7 Part 2 & 3, BS 5930:2015, REAM GL 6/2004 & BEM
Circular 4/2005
Generally BH/tests spacing shall be about 15m to 50m depending on site
terrains, geological formation, etc. For erratic subsoil such as limestone formation
areas or fill ground, more BH shall be carried out. BH shall only be terminated
after 5 consecutive SPT>50 or until strikes rock (min 4.5m rock coring). For high-
rise building or heavy structures, BH should only be terminated after at least
10 SPT>50 below the basement (if any) or minimum 4.5m into at least
slightly weathered rocks/ RQD>50%.
Important to ensure SI is ADEQUATE & RELIABLE. Adequate means
compliance with some established guidelines. Reliable means SI by
qualified SI Contractor (CIDB or ISO accredited) using proper equipment,
proper procedures & method and supervised by qualified personnel.
SI & GROUND CHARACTERISATION

Ground /subsurface characterization is more than SI. Misinterpretation from SI
without proper engineering judgment/experience/reported case histories can give
wrong profile/info. (Tomlinson, 1996)
81

Pile structural design requirements-pile shoe & joint
• Pile shoe design: functions & purposes, BS 8004 requirements &
standards? Pile shoe can be cast iron or Oslo point, but the area of
the top of the shoe should be such that the stress in the concrete
in this part of the pile is within the safe limits. Typical designs &
applications? When pile shoe is not needed? How to check
compliance?
• Pile joint design: functions & purposes, BS 8004 requirements
& standards? Typical designs, applications & technical basis?
Methods of testing? What to inspect & tests? Bending tests for
pile joint at site?
• Pile body structural design to take handling, installation (fc, fb
& ft) & working stress? BS 8004 requirements? Very complex soil-
structure interactions. CP requirements? Practice in other
countries? JKR standards & basis? QC tests? Abnormal loads due
to ground movement or treacherous subsoil conditions?
82

Pile Joint Quality & Testing
Importance of QC of welded pile joint when subject to hard driving,
tensile stress and bending stress. Welding temperature can up to about
1500o C with fire reddish colour, which can be disappeared after about 1
minute to 500/600o C. Needs about 2-5 minutes at normal air
temperature to cool down to about 100 to 200o C. Abrupt cool down by
water or paint will create micro-cracks to weaken welded joint.
1. Visual inspection & bending tests should be generally adequate. Why?
2. Ultrasonic Test
3. Radiographic Test
4. Performance (BS EN 12794)
83

84
PURPOSES &
FUNCTIONS OF PILE
SHOES. Important to
understand the principles
involved.
-To improve directional
stability & reduce
deviation of pile
alignment
-To protect the pile body.
How?
-To enhance socketing
effect
-To enhance toe
resistance
*Oslo point shall have
Brinell hardness >300 &
fy>700 MPa.

85
DESIGN CRITERIA
• Types: Welded, Bolted,
Mechanical Locking,
Connector Ring, Wedge
Sleeve & Dowel Splices, etc.
• Pile joint shall have same
strength of pile body to resist
bending, compressive, tensile,
torsional stress for installation
& service. Shall be checked
by bending tests (MS1314,
Part 1, 1993) or pile joint
robustness & rigidity test (BS
EN 12749)
• Shall have good workmanship
to maintain pile alignment
within permissible limits.
• PILE JOINT strength may
deteriorate by poor welding or
overdriving or corrosion, etc.

86
Welded spun pile
joint
Pile Joint Practice
• Check joint dimensional accuracy.
• Make sure the joint to be welded is
correctly cleaned by stiff wire brush or
grinder or sand paper to remove slag,
moisture, grease, rust, etc.
• Visual inspection to check weld
deficiencies & NDT such as magnetic
particle testing, Radiographic testing or
Ultrasonic testing, where necessary for
Preliminary piles.
• Common types of weld discontinuities:
Cracks (hot & cold cracks) & Craters
(caused by Ultrasonic pulling the electrode
way too soon). To avoid microcracks, at
least 2 to 5 minutes is required after
welding before re-piling.

87
Welding temperature can be up to
about 1500-2000o C but it will cool
down to about 800 to 500o C within
a minute. In about 2-5 minutes
time, the temperature can be
dropped about 100o -150oC.
If paint or water/coolant is applied
immediate after welding, rapid
cooling with subsequent
microcracking will be formed in
the weld.
For hard driving or driving with
likely high tensile stress, waiting
time for the welding to cool down is
at least 5 minutes.

88
BEARING CAPACITY of
ROCK POINTS (After
Rehnman, 1971)
Proper Oslo point shoe shall
have Brinell hardness >300,
fy.>700 MPa and no welding
to the hard steel. Design
principle & basis? How it
protects the pile body?

Oslo pile shoe. Design principles? Aimed to protect pile from damage when
encountered hard driving into rock, to improve directional stability, etc. To crush
the rock & the pile!
89

What to check before, during & after installation
of RC piles?
90
Visual inspection:
Welded joint shall be
visually free from
spatters, cracks,
undercuts, pitting,
degradable craters, slag
inclusion, blockholes or
other weld defects.
Tests?

Common malpractice /defects of Concrete Piles
91
1. MS 1314-Part 1: 1993 requires all corners of square concrete piles
should be chamfered or rounded as per BS 8006 & ACI 543R
requirements. ACI 543R has clearly stated that chambers at pile head
and pile tip are recommended to prevent concrete spalling during pile
driving.
2. High grade of concrete up to grade 80 has been claimed/used
without endorsement and certification by qualified concrete
technology expert/P Eng. RC pile head and tip may not achieve such
high strength, especially when the aggregate quality is not adequately
tested.
3. Welding of pile joints are commonly carried out by unqualified worker
without proper/adequate surface cleaning before welding. Anti-corrosion paint
is sometimes applied immediately after welding. This will result in more harm
than good. Worse is no bending test to verify workmanship at site to check
specification requirements for the welded joint is complied with especially for
hard/severe driving/jacking.
4. Lightly reinforced concrete piles with permissible Mc<5 MPa are
prone to crack during driving.

92
PILE JOINT DESIGN for high driving tensile stress. Design
principles & basis? Allowable weld strength?

Piling Issues for Displacement Piles
1. Important to be aware of the potential problems/risks, causes of the
problems/risks, principles involved, techniques to control or to
mitigate or to minimize the problems/risks.
2. Common piling problems in soft ground, hard or over driving & pile
damages, risks of displacement piles in limestone formation &
uncontrolled fill ground, false set, pile heave, etc.
3. Pile installation problems for displacement piles: WCGW at site for
various types of piles & installation methods in typical geological
formations (soft ground, limestone areas, filled ground & collapse
settlement & obstructions, boulders, erratic & inclined bedrock,
etc.)
4. Pile testing objectives & purpose? Common problems &
interpretation? Basis?
5. Driven pile termination criteria? Hammer selection basis?
6. SI problems: adequacy & reliability/accuracy (BEM Circular 5/2004)?
Critical info sought from SI?
7. ICE Spec for Piling & Embedded Retaining Walls (ICE, 2007 version).
JKR piling spec for road works (2018). Piling terminology & standard
BQ/preambles, Method statement, etc.
94

1. Typical piling problems in common geological formations
(refer Fig 4, 5, 6 & 6A). Mitigations?
2. Effective Mitigations Vs WCGW: site experience &
published case histories & guidelines, e.g. JKR Design
Guidelines for pile foundation in limestone formation, etc.
3. Common Piling Problems for Driven concrete piles.
4. Problems of Small Precast Concrete Piles.
5. Common misleading SI: case histories? consequences?
6. Piling spec: lacking & not comprehensive.
7. Piles in big group: excessive deviation, tilting, rotation, etc.
8. Overdriving & excessive driving stresses: fc, ft & fb
9. Piling equipment: suitability & adequacy
10.Method statement: very important as a QC tool, but
commonly overlooked or ignored by RE. Contents of MoS?
95
4.1PILING ISSUES-WHAT CAN GO WRONG?

How to mitigate against excessive
compressive, tensile & bending stresses for
displacement pile installation?
1. Overdriving means driving stress (fc, ft, fb) exceeds the
tolerable/permissible limits.
2. How to estimate the tolerable stress limits?
3. How to estimate the driving stresses? WEAP & Broms
method. Site monitoring (PDA)?
4. Soil response to piling: pore pressure, ground
vibration/movement/heave, noise, etc. How to assess
these problems? Acceptable limits?
5. Pile driving formula & theories. Wave equation, hammer,
packing, etc.
96

1. Common risks for driven concrete piles are structural damages
due to overdriving, excessive ground heave/vibration/movement or
scouring/aggressive ground or obstructions to installation (uncontrolled fill
ground or boulders abundant sites) or inclined bedrock (pinnacles, inclined
beddings); inadequate reinforcement or structural strength to take the
handling stress, driving stress, stress due to soil movements (down drag or
lateral deflection) or verticality (joints & slenderness). How these can
happen & necessary mitigations?
2. Common problems for driven concrete piles in soft
ground/coastal alluvium: excessive driving stress (compr & tensile)
when penetrating through lenses of sand into soft underlying clay,
difficulties in pile cap construction. Pile directional stability & excessive loss
of fs, etc. Mitigations?
3. What can go wrong will go wrong unless effective mitigations are in
place. Awareness, understanding & working knowledge. Reported case
histories?
4. How to assess the problems? Acceptable limits?
5. A test is better than hundreds of expert opinions.
97
4.2 DISPLACEMENT PILES - WHAT CAN GO WRONG?

1. Purpose of packing or cushion for pile & hammer during
driving? Why cushion shall be regularly replaced? Guides?
2. STD Spec (MS 1314) requirements of concrete piles
(thk, workmanship, tolerance) for MS plate welded joint? Effect of
1mm gap & heat sink problems?
3. Pile shoe design principle? Why important? Rock shoe (Oslo
point) design requirements?
4. Very important to understand the driving stress for
concrete piles! Permissible driving stress for RC & prestressed
piles (AS 2159, AASHTO, CGM)? How to estimate driving stress (fc,
ft, fb) based on packing conditions, hammer wt & drop, eccentric
hammering by WEAP or Prof Broms method and HSDT (ASTM
D4945-12)? Refer Table 7.
5. Swedish Building Code: For difficult site or hard driving, Class A
RC pile shall be used (fcu>50, rebar>1.2%, inspection tube shall
be included to check straightness & inspection by cctv, etc.).
Discount Qdesign for joints & slenderness. Qdesign<MC/0.15xpile size
(Broms). Mc shall be based on crack width of 0.2mm (non-
aggressive ground) to 0.1mm? 98
4.3 DISPLACEMENT PILES – WCGW-2?

1
2
3
4
5
6
7
8
9
10
11
12
13
14
PILE DRIVEN TO SET BUT
DAMAGED BY DEFLECTION DUE
TO BIG BOULDER. DAMAGE CAN
BE DETERIORATED AFTER
DRAGDOWN FORCE BY
SETTLEMENT OF FILL DUE TO
SATURATION AS THE RESULT OF
INFILTRATION OF SURFACE
RUNOFF OR CAPALLARY ACTION
FROM WATER TABLE.
PILE DRIVEN TO SET
WITH SOME SMALL
BOULDERS NEAR PILE
TIP. BEARING
CAPACITY IS REDUCED
AFTER THE BOULDERS
SOFTENED DUE TO
SUBSEQUENT WETTING
& SATURATION.
PILE DRIVEN TO PROPER
SET IN ORIGINAL HARD
LAYER. SOME SMALL
SETTLEMENT (<10mm) DUE
TO DRAG DOWN FORCE
CAUSED BY COLLAPSE
SETTLEMENT AS THE
RESULT OF WETTING BY
INFILTRATION & CAPALLARY
ACTION FROM WATER
TABLE.
DRAGDOWN FORCE
LARGE SETTLEMENT SOME SETTLEMENT SMALL SETTLEMENT
BIG BOULDER
FINAL WATER TABLE
O.G.L
ORIGINAL WATER
TABLE
FILL
PILECAP
F.L
POSSIBLE PILE CONDITIONS AFTER DRIVEN TO SET IN NEWLY FILL GROUND
DEPTH
(m)
PONDING
SMALL SETTLEMENT
PILE DRIVEN TO SET
ON BIG BOULDER IN
THE FILL
GROUND
SETTLEMENT
GROUND
SETTLEMENT
GROUND
SETTLEMENT
GROUND
SETTLEMENT
Piling Problems in Newly Filled Ground: Normal settlement of well compacted
fill<2%, collapse settlement. Causes? Mitigations?
99

PILING PROBLEMS due to overdriving
101

PILING PROBLEMS in soft coastal alluviums
102

PILING PROBLEMS in Metasedimentary rock formation –
undetected problems?
104

FIG. 6A:
PROBLEMS OF LONG SLENDER
PILE IN THICK soft ground SOFT
GROUND
105

How pile head can be damaged by overdriving?
Mainly eccentric hammering due to packing/pile
cushion deterioration or pile head MS plate not
perpendicular pile axial or pile head structural
reinforcement inadequacy or combination factors.
106

107
PILING PROBLEMS – DEFECTIVE PILES. Causes?
Seriously damaged pile due
to severe driving stress in
soft ground (excessive
dynamic tensile or bending
stress or both?)
Defect due to poor
workmanship of pile
casting

PILING PROBLEM – DEFECTIVE PILES
Defective pile shoe
-Poor workmanship
Problems of
defective pile head
& overdriving!
108

109
Cracks&
fractured
Non-
chamfered
corners

When pile head can be crushed
like this?
111

112
Problems of driven Piles
2. Pile Head Damages
Pile Head Damages for various type of piles.
Causes: overdriving; eccentric hammering; ???
Causes of Problems: excessive compression driving stresses

Pile head defect due to hard driving
or poor workmanship
113

PILING PROBLEMS – SOFT GROUND
114

PILING PROBLEMS – SOFT GROUND
Ground heave due to
pressure relief at base
& surcharge near
excavation
Pile tilts & moves/walks

PILING PROBLEMS IN SOFT GROUND.
Mitigations?
116

Observed Spun Pile Joint damages in soft ground by cctv (high
driving tensile stress)

Pile Joint Damages
118
Pile Joint Damages for reinforced concrete piles.
Cause of Problems: welded joint failure due to poor
welding
Pile Joint Damages for steel
pipe piles. (extracted from
ground)
Cause of Problems:
excessive buckling or
poor welding
Inspection & bending test
(MS 1314) is the solution.
Source: Geo-Photo
Source: Gue And Partners

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