Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020)

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The Contractor shall provide a complete set of recorded test data, as described in this section, with
interpretation of test results, within seven days of completion testing. Interpretation of test results
shall comply with directions from the Engineer.

The Contractor shall provide the following details about tested piles, where applicable:

a. General details

Site location
The Contract identification
Proposed structure
The main Contractor
The piling Contractor
The Engineer
The Owner
Date of test

b. Pile details

Identification (number and location)
Position relative to adjacent piles
Brief description of location (for example, whether the tested pile is on a pier, abutment,

cofferdam, or over water)

Ground level at the tested pile

’s location

Head level at which the test load was applied
Type of pile (whether vertical, raking, compression, or tension)
Shape and size of

the tested pile’s cross-section and the cross-section’s change in

position

Head details
Length in ground
Level of toe
Any permanent casing or core
Pile reference
Concrete mix grading and water-to-concrete (w/c) ratio
Aggregate type and source
Cement type
Slump
Cube test results for the tested pile and cap
Reinforcement

c. Installation details

Dates and times of boring and concreting of test pile and adjacent pile
Date and time when concrete was cast for the tested pile

’s cap

Start and finish of each operation during installation of a pile and subsequent testing
Any difficulties in boring, handling, pitching, and driving a pile
Any delays in testing caused by sea, water and weather conditions
Pile diameter
All instrument readings
Concrete strength (when tested)
Date cast
Date of test
Length of reinforcement cage
Water table below ground level
Length of casing
Description of soil for the length of pile (for bored piles and pre-drilling only)
Unusual events or data and movements of the test pile
Any other relevant information requested by the Engineer

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d. Test procedure details

Weight of kentledge
Tension pile, ground anchor, or compression pile details
Plan of test arrangement, showing position and distances of kentledge support, rafts,

tension, or compression piles and relationship of the reference frame to the tested
pile

Jack capacity
Calibration certificates of pressure gauges and dial gauges
Method of load measurement
Proof test by maintained loading
Relevant dates and times

e. Test results

Result data (in a table)
Result data, including load plotted against settlement, load, and settlement (in graphic

form, plotting resultant values over time)

Ground heave

f. Site investigation details

Site investigation report number
Borehole reference

17.16.10 Failure of Working Load Test

Load testing for a pile or pile group shall indicate failure if any one of the following observations is
recorded:

a. A pil

e’s settlement under one working load exceeds 10 mm or the allowable settlement

defined in the Contract standard specifications

b. Residual settlement after removal of the test load of one working load exceeds 4 mm or the

allowable settlement defined in the Contract standard specifications

c.  Instability of the kentledge prevented completion of the test
d.  Failure of the pile cap, through whatever cause, prevented completion of the test
e.  An involved measuring instrument was tampered with in any way
f.  A  pile  tested  cracked,  crumbled,  distorted  from  its  original  shape,  was  deflected  from  its

original position, or was otherwise dislocated, marred, damaged, or destroyed

The Contractor shall not be paid for any pile or pile group that fails testing. The Contractor shall bear
the cost for redesign and enlargement of pile caps or, if necessary, for replacement piles. The Owner
shall pay for piles that successfully pass testing, as specified in the Contract documents for the
Project.

17.16.11 Compensating Piles

The Contractor shall replace any pile or pile group that fails under the working load test with one or
more piles in accordance with directions from the Engineer and at no extra cost to the Owner.

If, in the opinion of the Engineer, it is impractical or unadvisable to install substitute piles in place of
a failed pile, the Contractor shall propose a solution to the Engineer for consideration and approval.
The Contractor shall be fully responsible for all costs incurred and any losses incurred by the Owner
for changes in the design of the structure or delay to the Contract that arising from the Contract

or’s

proposal.

For each working load test that fails, the Contractor shall carry out, at no extra cost to the Owner, an
additional working load test on a pile selected by the Engineer.

If the additional working load test on the selected pile also shows that this pile is unable to satisfy
the acceptance requirements, then all the piled installed in a similar condition will be considered as

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failed. The capacity of piles installed shall be suitably downgraded based on the working load test
results. Any additional piles required as a result of such reduction in pile capacity, including the cost
for amending pile caps and ground beams, shall be entirely at the Contract

or’s expense. The

Engineer

’s decision on this matter shall be final.

17.16.12 Reinstatement of Piles After Testing

After completing a test, the Contractor shall check all equipment and measuring devices, dismantle
them, and either store them on the Project site for future tests or remove them from the site.

The Contractor shall remove kentledge systems and their supporting structures from the piles they
tested and either store these systems on the Project site for future tests or remove them from the
site.

After completing a Non-working load test, the Contractor shall cut off temporary piles and ground
anchors at least one metre below ground level or as directed by the Engineer, removed them from
the Project site, and use approved material to restore the ground.

On completing a working load test, the Contractor shall either remove temporary piles and ground
anchors by cutting them off below ground level and using approved materials to restore the ground
or, with the

Ownerr’s authorization, incorporate the temporary piles and ground anchors into the

permanents works.

A tested pile

’s cap, if concrete, shall be broken up and removed from the Project site. If a tested

pile

’s cap is steel, shall be cut off and either stored for use in future tests or removed from the site.

The Contractor shall leave the tested pile in a condition that it is ready for incorporation into the
permanent works.

17.17

Osterberg Cell Load Testing

17.17.1

General

The test shall be carried out in accordance with ASTM D1143/D1143M-07e1. This work shall consist
of furnishing all materials and labour necessary for conducting an Osterberg Cell (O-cell) Load Test
and reporting the results. The Contractor will be required to supply material and labour as hereinafter
specified and including prior to, during and after the load test. The piles used for the load test program
will be instrumented by specialized firm (the Osterberg Cell supplier) or others, as approved by the
Engineer. The Osterberg cell load test will be conducted by (the Osterberg Cell supplier), or others,
as approved by the Engineer, with the Contractor providing auxiliary equipment and services as
deemed required. The O-cell load test is a non-destructive test and is suitable for both dedicated test
piles and working test piles. If the test pile is constructed on working pile (intended to carry structural
service loads) it shall be left in a condition suitable for use in the finished structure.

17.17.2

Materials

The Contractor shall supply all materials required to install the Osterberg cell, conduct the load test,
and remove the load test apparatus as required.

The Contractor shall furnish one (1) or more Osterberg Cells as required for each load test, to be
supplied by approved firm. The Osterberg cell(s) to be provided shall have the required capacity and
shall be equipped with all necessary hydraulic lines, fittings, pressure source, pressure gage and
telltale devices. Required materials include, but not limited to the followings:

a. Fresh, clean, potable water from an approved source to be used as hydraulic fluid to

pressurize the Osterberg Cell.

b. Materials sufficient to construct a stable reference beam system for monitoring movements

of the pile during testing. The system shall be supported at a minimum distance of 3 pile
diameters from the centre of the test pile to minimize disturbance of the reference system. A
good quality, self-levelling

surveyor’s level shall be provided to monitor the reference system.

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c. Materials sufficient to construct a protected work area (including provisions such as a tent or

shed for protection from inclement weather for the load test equipment and personnel) of size
and type required by the Engineer and Osterberg Cell supplier. The protected works area
shall be maintained at adequate temperature as recommended by testing equipment supplier
in order to insure proper operation of the load testing equipment.

d. Stable electric power source, as required for lights, welding, instruments, etc.
e. Materials for carrier frame, steel bearing plates and/or other devices needed to attach O-cell

to rebar cage, as required.

Materials supplied, which do not become a part of the finished structure become the responsibility
of the Contractor at the conclusion of the load test and shall be removed from the job site.

17.17.3

Equipment

The Contractor shall supply equipment required to install the Osterberg cell, conduct the load test,
and remove the load test apparatus as required. Required equipment includes but is not limited to:

a. Welding equipment certified welding personnel and labour as required, to assemble the test

equipment under the supervision of Osterberg Cell supplier personnel, attach instrumentation
to the Osterberg cell(s), and prepare the work area.

b. Equipment and labour to construct the steel reinforcing cage and/or placement frame

including any steel bearing plates required for the test pile.

c. Equipment and operators for handling the Osterberg cell, instrumentation and placement

frame or steel reinforcing cage during the installation of the Osterberg cell and during the
conduct of the test, including but not limited to a crane or other lifting device, manual labour,
and hand tools as required by Osterberg Cell supplier. and the Engineer.

d. Equipment and labour sufficient to erect the protected work area and reference beam system,

to be constructed to the requirements of the Engineer and “Osterberg Cell supplier”.

e. Air compressor for pump operation during the load test.

17.17.4

Procedure

For the pile(s) selected for testing by the Engineer, the Contractor shall construct the piles using the
approved pile installation techniques until the piles excavation has been completed.

The  Osterberg  Cell,  hydraulic  supply  lines  and  other  instruments  shall  be  assembled  and  made
ready for installation under the direction of “Osterberg Cell supplier” and the Engineer, in a suitable
area, adjacent to the test pile, to be provided by the Contractor. The Osterberg Cell assembly shall
be welded to the bottom of the cage in conjunction with the construction of the cage. The plane of
the  bottom  plate(s)  of the O-cell(s) shall  be set  at  a right  angle to  the  long  axis  of the cage. The
Contractor  shall  use  the  utmost  care  in  handling  the  test  assembly  so  as  not  to  damage  the
instrumentation  during  installation.  The  contractor  shall  limit  the  deflection  of  the  cage  to  0.6m
between  pick  points  while  lifting  the  cage  from  the  horizontal  position  to  vertical.  The  maximum
spacing  between  pick  points  shall  be  7.5m.  The  contractor  shall  provide  support  bracing,  strong
backs, etc. to maintain the deflection within the specified tolerance. The O-cell assembly must remain
perpendicular to the long axis of the reinforcing cage throughout the lifting and installation process.

When the test pile drilling has been completed, inspected and accepted by the Engineer, the O-cell
assembly and the reinforcing steel may be installed. A seating layer of concrete or grout shall be
placed by an approved method, in the base of the pile to provide a level base and reaction for the
O-cell. The preferred method is to install the O-cell assembly and deliver the seating layer using a
pump line or tremie pipe extending through the O-cell assembly to the base of the pile. Depending
on the configuration of the test assembly, it may be necessary to deliver the seating layer of concrete
prior to installing the O-cell. In this case, the O-cell assembly shall be installed while the concrete or
grout at the base is still fluid, under the direction of “Osterberg Cell supplier” and the Engineer. The
Osterberg Cell should end up at least partially submerged and firmly seated into the base grout or
concrete.

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After seating the Osterberg cell, the remainder of the piles shall be concreted in a manner similar to
that specified for production piles. At least four (4) concrete test cubes sets, in addition to those
specified elsewhere, shall be made from the concrete used in the test pile, to be tested at the
direction of “Osterberg Cell supplier”, at least one of these test sets shall be tested prior to the load
test and at least two sets shall be tested on the day of the load test.

During the load test, no casings may be vibrated into place in the foundation area near the load test.
Drilling may not continue within a 30-m radius of the test pile. If test apparatus shows any interference
due to construction activities outside of this perimeter, such activities shall cease immediately.

After the completion of the load test, and at the direction of the Engineer, the Contractor shall remove
any equipment, material, waste, etc. which are not to be a part of the finished structure. If the load
test pile is constructed at a production location and intended to carry service loads, the Contractor
shall grout the interior of the Osterberg cell and annular space around the outside of the Osterberg
cell using grouting techniques ap

proved by the Engineer and “Osterberg Cell supplier”

17.17.5

Testing and Reporting

The load testing shall be performed by a qualified geotechnical engineer approved in advance by
the Engineer. The geotechnical engineer must have a demonstrated knowledge of load testing
procedures, and have performed at least 10 Osterberg cell load tests within the past two years.

The load testing shall be performed in general compliance with ASTM D 1143/D1143M-07e1
Standard Test Method for Piles Under Static Axial Load. The magnitude of the load increments may
be increased or decreased depending on the Project requirements but should not be changed during
the test.

Direct movement indicator measurements shall be made of the following:

a.  O-cell expansion either directly or with telltales (minimum of 3 indicators required),
b.  Upward top-of-pile displacement (minimum of 2 indicators required), and
c.  Pile compression above O-cell (minimum of 2 indicators required).

Loads shall be applied at the prescribed intervals until the ultimate capacity of the pile is reached in
either end bearing or side friction, until the maximum capacity or maximum stroke of the O-cell is
reached, or unless otherwise directed by the Engineer.

At each load increment, or decrement, movement indicators shall be read at 1, 2, 4 and 8 minute
intervals while the load is held constant.

During unloading cycles the load decrement shall be such that at least 4 data points are acquired for
the load versus movement curve. Additional cycles of loading and unloading using similar
procedures may be required by the Engineer following the completion of the initial test cycle.

Digital dial gages, used to measure O-cell expansion and top-of-pile displacement should have a
minimum travel of 100mm and be capable of being read to the nearest 0.025mm division. When O-
cell expansion is measured directly, dial gages capable of measuring the full stroke of the Osterberg
Cell will be used (typically 150mm). Digital dial gages, used to measure pile compression should
have a minimum travel of 25mm and be capable of being read to the nearest 0.025mm division.

Unless otherwise specified by the Engineer, the Contractor will supply four (4) copies of a report of
each load test, as prepared by “Osterberg Cell supplier” or others approved by the Engineer. An
initial data report containing the load-movement curves and data tables will be provided to the
Engineer within three (3) days of the completion of load testing, to allow evaluation of the test results.
A final report on the load testing shall be submitted to the Engineer within ten (10) working days after
completion of the load testing.

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17.18

Tension and Lateral Load Testing

When specified, the Contractor shall conduct tension static load tests and lateral load tests, which
shall comply

with the ASTM’s

Standard Test Methods for Deep Foundations Under Static Axial

Tensile Load

(ASTM D3689-07)

and ASTM’s

Standard Test Methods for Piles Under Lateral Loads

(ASTM D3966-07)

17.19

Integrity Testing for Piles

Integrity testing for drilled foundation piles shall comply with the requirements outlined in this section.

17.19.1

Low Strain Integrity Testing for Piles

Integrity testing for piles provides information about physical dimensions, continuity, and the
consistency of materials used. Such tests do not obtain direct information about the performance of
piles under actual loads.

Low strain integrity tests do not replace static load tests; rather, they are a source of supplementary
information.

If the Engineer identifies any anomalies in the results of low strain integrity tests, the Engineer may
call for further testing to determine the cause, nature, and extent of such anomalies and to ascertain
whether the pile is satisfactory for its intended use.

The  firm  that  has  been  approved  by  the  Engineer  shall  conduct  all  low  strain  integrity  testing  in
accordance  with  ASTM  D5882-07  and  only  personnel  with  the  appropriate  competence  and
knowledge shall interpret such tests. The Contractor shall submit full tests results and findings to the
Engineer no later than ten days after the completion of each phase of testing. The Contractor shall
provide  full  details  of  the  ground  conditions,  pile  dimensions,  and  construction  methods  to  the
specialist firm when doing so is necessary to facilitate interpretation.

Integrity tests shall not occur until seven or more days have elapsed after pile casting, unless the
Engineer specifies otherwise.

A test pile

’s head shall be clean, free from water, laitance, and loose concrete, and readily accessible

for the testing.

The Contractor shall carry out low strain integrity testing on all in-situ concrete bored piles unless
otherwise directed by the Engineer.

17.19.2

Cross-hole Sonic Logging

As specified in the Contract documents, the Contractor shall perform cross-hole sonic logging (CSL)
tests in accordance with ASTM D6760-08. To accommodate CSL testing, the Contractor shall furnish
and install access tubes in accordance with the following requirements:

a. Access tubes for cross-hole sonic log testing shall be steel pipe with walls at least 3.5 mm

thick and inside diameters of at least 38 mm.

b. Access tubes shall have round, regular inside diameters that lack defects and obstructions.

Access tubes shall have pipe joints that permit the free, unobstructed passage of source and
receiver probes that have diameters up to 33 mm.

c. Access tubes shall be watertight and free from corrosion. They shall have clean internal and

external faces to ensure that they bond well with concrete.

d. Each access tube shall have watertight threaded caps on its bottom and its top.

The  Contractor  shall  install  access  tubes  for  CSL  testing  in  all  drilled  piles,  except  as  otherwise
noted, to permit access for the CSL test probes. If, in the opinion of the Engineer, the condition of
the pile excavation permits pile construction in the dry, the  Engineer may specify  the omission of
such CSL testing.

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The Contractor shall securely attach access tubes to the interior of

a test pile’s reinforcement cage.

One access tube shall be furnished and installed for each 300 mm of pile diameter, rounded to the
nearest  whole  number,  as  shown  in  the  Contract  plans.  Such  testing  shall  involve  at  least  three
tubes.  Access  tubes  shall  be  placed  around  the  pile  to  be  tested,  inside  the  spiral  or  hoop
reinforcement, and at least 75 mm away from the vertical reinforcement. Spacing of access tubes
shall be uniform, as measured along the circle passing through the centres of the access tubes. If
space  prevents  compliance  with  these  minimum  requirements,  the  Contractor  shall  bundle  the
access tubes with the vertical reinforcement. If reinforcing steel does not extend to the bottom of the
test pile, the CSL tubes shall extend to the pile

’s bottom.

If a cage requires trimming and access tubes for CSL testing are attached to the cage, the Contractor
shall either shift the access tubes up the cage or cut the access tubes. When cutting tubes, the
Contractor shall ensure that its ends are adapted to receive a watertight cap, as specified.

Access tubes shall be in straight alignment and as parallel to the vertical axis of a reinforcement
cage as possible. Access tubes shall extend from the bottom of a test pile to at least 600 mm above
the top of that pile. Splice joints in the access tubes, if required to achieve full length access tubes,
shall be watertight.

The Contractor shall clear access tubes of all debris and extraneous materials before installing them.
When installing a reinforcement cage and placing concrete, the Contractor shall be careful not to
damage access tubes.

Before placing concrete, the Contractor shall fill the access tubes with potable water and reinstall
the watertight threaded caps

on the tube’s top ends.

Before performing any CSL testing operations, as specified in these specifications, the Contractor
shall remove the concrete at the top of the pile to be tested down to sound concrete.

The Contractor shall perform CSL testing and analysis on all completed piles that the Engineer
designates for testing. The Contractor shall notify the Engineer at least 48 hours before the concrete
in each pile will be sufficiently cured for CSL testing.

CSL testing shall occur after the pile concrete has cured for at least 96 hours. Additional curing time
may be necessary if concrete for a test pile contains admixtures, such as a set-retarding admixture
or water-reducing admixture. Additional curing time under these circumstances shall not be grounds
for the Owner to give the Contractor additional compensation or extension of time. Until the Engineer
inspects and approves a CSL-tested pile, the Contractor shall not conduct any subsequent
construction. CSL tested shall be complete no later than seven days after placement of a pile.

After placing concrete for a test pile but before starting CSL testing for that pile, the Contractor shall
inspect the access tubes. Each access tube that the test probe cannot pass through shall be
replaced, at the Contractor's expense, with a 50 mm diameter hole cored through the concrete for
the entire length of the pile. If a single tube is blocked, the Engineer may perform CSL testing on the
remaining tubes. If no anomalies are noted, the Engineer may waive the requirement to provide the
cored alternative hole. The Contractor shall provide computer log information and interpretation in
their original formats.

The Engineer shall review the CSL test results, analyses for tested piles, and the visual inspection
reports for a subject pile to determine whether it has passed such testing.

The Engineer may approve the continuation of pile construction before approval and acceptance of
the first pile, if the Engineer's observes the following conditions:

a. Construction of the first pile is satisfactory
b.

A test pile’s installation conforms to the pile installation plan

c. Daily reports provided by the Contractor are satisfactory
d.

An inspector’s daily logs concerning excavation, steel reinforcing bar placement, and
concrete placement are satisfactory

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If the Engineer determines that the concrete placed under support fluid for a given pile is structurally
inadequate, that pile shall be rejected. In such cases, placement of concrete under slurry shall be
suspended until the Contractor submits to the Engineer written changes to the methods of pile
construction that will prevent structurally inadequate piles in the future and the Engineer approves
the submittal in writing.

The Engineer may direct the Contractor to drill a core hole in any pile of questionable quality pile (as
determined from CSL testing and analysis or by the Engineer

’s direct observation) to further explore

the condition of the pile.

Before beginning coring, the Contractor shall submit the method and equipment to be used to drill
and remove cores from pile concrete to the Engineer. The Contractor shall not begin coring until
receiving the Engineer

’s written approval to do so. Coring methods and equipment shall ensure

complete core recovery while minimising abrasion and core erosion.

If subsequent testing at a pile indicates the presence of defects, the Contractor shall bear the testing
costs and any delay costs that result from required additional testing.

For all piles that are determined to be unacceptable, the Contractor shall submit a plan for further
investigation and remedial action to the Engineer for approval. All modifications to the dimensions of
the piles, as shown in the Contract plans, that are required by the investigation and the remedial
action plan shall be supported by calculations and working drawings. The Contractor shall not begin
repair operations until receiving the Engineer's approval of the investigation and remedial action
plan.

All access tubes and cored holes shall be dewatered and filled with grout after tests are completed
and a pile is accepted. Access tubes and cored holes shall be filled using grout hoses that extend to
the bottom of the tube or hole or into the grout already placed.

Grout for filling the access tubes at the completion of the cross-hole sonic log tests shall be a grout
with a maximum water-to-cement (w/c) ratio of 0.45 or as directed by the Engineer.

17.20

High Strain Dynamic Test

17.20.1

General

High strain dynamic tests shall be carried out in accordance with ASTM D4945-12. Dynamic pile
testing involves monitoring the response of a pile to a heavy impact applied at the pile head. The
impact is often provided by a hammer and response is normally measured in terms of force and
acceleration or displacement close to the pile head.

The results directly obtained refer to dynamic loading conditions. Interpretation in terms of static
loading requires soil and pile dependent adjustments, and corroboration from experience may be
required to correlate dynamic testing with normal static load tests

Details of the equipment to be used and of the method of analysis of test results shall be provided
to the Engineer before the commencement of testing.

17.20.2

Measuring Instruments

All  instruments  affixed  to  the  pile  for  the  purpose  of  measuring  stress  and  movement,  and  all
equipment  for  receiving  and  processing  data  shall  be  suitable  for  the  purpose.  The  equipment
required  to  be  attached to the  pile  shall  be  approximately  positioned  and fixed to  the  approval  of
Engineer.

17.20.3

Hammer

The hammer and all other equipment used shall be capable of delivering an impact force sufficient
to mobilize the equivalent specified test load without damaging the pile.

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17.20.4

Preparation of the Pile Head

The preparation of the pile head for the application of the dynamic test load shall involve, where
appropriate, trimming the head, cleaning and building up the pile using materials which will at the
time of testing safely withstand the impact stresses. The impact surface shall be flat and normal to
the axis of the pile.

17.20.5

Time of Testing

Dynamic load tests shall be carried out at appropriate and approved times after pile installation. The
time between the completion of installation and testing for a cast-in-place concrete piles shall be
after the concrete has reached 75% of its specified 28 day strength so that the pile is not damaged
under the impact stresses.

17.20.6

Results

Initial results shall be provided to the Engineer within 24 hours of the completion of a test.
These shall include:

1.  The maximum force applied to the pile head.
2.  The maximum pile head velocity.
3.  The maximum energy imparted to the pile.

Normally within 10 days of the completion of testing final report shall be given to the Engineer
which includes:

1.  Date of pile installation
2.  Date of test
3.  Pile identification number and location
4.  Length of pile below ground surface
5.  Total pile length, including projection above commencing surface at time of test.
6.  Length of pile from instrumentation position to tip.
7.  Hammer type, drop and other relevant details.
8.  Blow selected for analysis.
9.  Test load achieved (i.e. total mobilized deduced static load).
10. Pile head movement at equivalent design verification load.
11. Pile  head  movement  at  equivalent  design  verification  load  plus  50%  of  specified  working

load.

12. Pile head movement at maximum applied test load.
13. Permanent residual movement of pile head after each blow.
14. Temporary compression.

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Index

adjacent structures, 17-3
allowable settlement, 17-16, 17-24
augers, 17-2
bailing buckets, 17-2
bell footing, 17-6
Bentonite, 17-9, 17-10
boring piles, 17-3
casings, 17-2, 17-7, 17-11, 17-12, 17-14, 17-

15, 17-27

cleaning equipment, 17-2
Concrete, 17-12, 17-13, 17-14, 17-23
concrete pumps, 17-2
cranes, 17-2
cross-hole sonic logging, 17-28
Department of Transport, 17-4
desanding equipment, 17-2, 17-9
disturbances, 17-3
drilling fluid, 17-8, 17-9, 17-10, 17-12, 17-13,

17-14, 17-15

drilling operations, 17-3
drills, 17-2, 17-3
dry bores, 17-14, 17-15
dry excavation, 17-7
dynamic testing, 17-16, 17-30
effective life-saving, 17-3
embankment placement, 17-6
excessive caving, 17-5
existing structures, 17-5
ground formations, 17-2
groundwater table, 17-7
halting, 17-22
hammer, 17-7, 17-12, 17-30
High strain dynamic tests, 17-30
hydraulic rams, 17-19
Initial results, 17-31
installation plan, 17-2, 17-29
jacks, 17-17, 17-19, 17-20
kentledge, 17-16, 17-17, 17-18, 17-19, 17-20,

17-22, 17-24, 17-25

lateral load tests, 17-28
load measuring device, 17-16, 17-17
loading, 17-16, 17-17, 17-18, 17-19, 17-21,

17-22, 17-24, 17-27, 17-30

loading test, 17-16
mineral grain, 17-9
mineral slurry, 17-7, 17-9
noises, 17-3
obstructions, 17-4, 17-28
Osterberg Cell, 17-25, 17-26, 17-27
permanent casing, 17-4, 17-6, 17-7, 17-23
permanent lining tubes, 17-15
pile construction, 17-2, 17-5, 17-6, 17-10, 17-

28, 17-29, 17-30

Pile construction records, 17-4
pile head, 17-30, 17-31
pile test, 17-19
pile tests, 17-16, 17-18, 17-19, 17-20
piling, 17-3, 17-4, 17-6, 17-15, 17-16, 17-23
Polymer slurries, 17-10
precautions, 17-5, 17-10, 17-14
reinforcing cage, 17-7, 17-13, 17-14, 17-26
sampling equipment, 17-2
settlement, 17-16, 17-17, 17-19, 17-20, 17-22,

17-24

slurry pumps, 17-2
Static load tests, 17-20
temporary casing, 17-4, 17-6, 17-7, 17-11, 17-

12, 17-14, 17-15

tension static load tests, 17-28
tolerances, 17-5, 17-15
tremies, 17-2
unloading, 17-21, 17-27
utilities, 17-5
vibrations, 17-3, 17-5
Welding, 17-26
wet excavation method, 17-7
working pile, 17-16, 17-19, 17-25

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DRIVEN PILES

This chapter outlines standards and requirements for driven piles for the Project. Such work consists
of furnishing and driving foundation piles of the type and dimensions designated in the Contract
documents and, when required, cutting off or building up foundation piles. The Contractor shall
comply with the specifications in this chapter whenever providing such work for the Project.

This chapter also requires the Contractor to provide test piles and perform loading tests. In
accordance with the specifications in this chapter, the Contractor shall install piling at the locations
shown in the Contract documents, or as directed by the Engineer, to the required elevations,
penetrations, and nominal resistances.

Except  when  test  piles  are  required,  the  Contractor  shall  furnish  piles  in  accordance  with  the
dimensions  shown  in  the  Contract  documents.  When  Non-working  test  pile  are  required,  the
Contractor shall use the production pile lengths shown in the Contract documents as estimates; the
Engineer shall determine  actual lengths for production piles after test piles have been driven and
tested. The Engineer shall give the Contractor an order list that includes pile lengths for use in the
completed structure.

As necessary to suit the method of operation, the Contractor shall increase the lengths shown in the
Engineer

’s ordered list to provide for fresh heading, without additional compensation.

18.1

Pile Driving Terminology

This section defines core terminology for pile driving the related work covered in this chapter.

Blow Count: A total of the hammer blows that are required to cause 300 mm or 25 mm of
penetration.

Driving Record:

Record of blow count per unit penetration for the entire driving of a pile.

Dynamic Testing:

Also called high strain dynamic pile testing, dynamic testing requires

impacting a pile with a pile driving hammer or a large drop weight and measuring the force and
velocity in the pile with pile analyzer instruments.

Jetting: A technique in which pile installers use water and air to facilitate pile penetration by displacing
soil.

Nominal Resistance: A value that represent

s a pile’s ultimate capacity.

Pile Shoes:

Steel plates that protect all types of piles for which hard driving is expected.

Pre-Drilling:

A process in which the Contractor drills a hole with a continuous flight auger or a wet

rotary bit to remove some soil or loosen the strata.

Probe Pile:

A pile that is driven to determine the required pile length at various locations on a site.

It may be also called an indicator pile or test pile.

18.2

Reference Standards and Codes

Standards and codes for Driven Piles shall be as specified in these specifications, in the Contract
documents, if any, and the following, in their latest edition:

•

AASHTO LRFD

American Association of State Highway and Transportation Officials -

Load and Resistance Factor Design, Bridge Construction Specifications;

•

AASHTO LRFD

American Association of State Highway and Transportation Officials -

Load and Resistance Factor Design, Bridge Design Specifications;

•

AASHTO

Standard Specifications for Transportation Materials and Methods of

Sampling and Testing;

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•

ADQCC (TR-516)

Road Structures Design Manual;

•

ASTM American Society for Testing and Materials.

Table 18-1 presents AASHTO and American Society for Testing and Materials (ASTM) standards
that are related to materials for driven piles. It includes designations and titles.

Table 18-1: Designations and titles for AASHTO and ASTM standards that apply to driven

piles works

AASHTO

DESIGNATION

ASTM

DESIGNATION

TITLE

ASTM A36/A36M-
08

Standard Specification for Carbon Structural Steel

ASTM
A572/A572M-12

Standard Specification for High-Strength Low-Alloy
Columbium-Vanadium Structural Steel

ASTM
A992/A992M-11

Standard Specification for Structural Steel Shapes

ASTM
A148/A148M-08

Standard Specification for Steel Castings, High Strength, for
Structural Purposes

18.3

Materials for Pile Driving

Materials for pile driving shall comply with the standards and requirements outlined in this section.

18.3.1

Steel Piles

18.3.1.1

Rolled Structural Steel Piles

Properties of Rolled Structural Steel Piles

Steel used in rolled structural steel piles shall conform to the following standard specifications of the
American Society for Testing and Materials (ASTM):

•

Standard Specification for Carbon Structural Steel (ASTM A36/A36M)

•

Standard Specification for High-Strength Low-Alloy Columbium-Vanadium Structural Steel

(ASTM A572/A572M)

•

Standard Specification for Structural Steel Shapes (ASTM A992/A992M)

In addition to the standards listed above, the Contractor may use steel that is ordered or produced
in compliance with other standards or other published ASTM specifications that establish properties
and suitability for such steel.

Cast steel shoes, if used, shall be grade 90-60 steel that conforms to the ASTM

Standard

Specification for Steel Castings, High Strength, for Structural Purposes

(ASTM A148/A148M). The

Contractor shall consider using pile shoes when structural steel shapes are driven through
obstructions or into sloping hard rock. Refer to Article 18.4.2.2 for more information on pile shoes.

Minimum Dimensions for Rolled Structural Steel Piles

Sections of such piles shall be

of “H” or “W” shape and shall comply with the following requirements:

A pile’s flange the projection shall not exceed 14 times the minimum thickness of metal in
either the flange or the web, and flange widths shall not be less than 80% of the depth of the
section.

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A pile’s nominal depth in the direction of the web shall not be less than 200 mm.

Flanges and webs shall have minimum nominal thicknesses of at least 9.5 mm.

18.3.1.2

Steel Pipe Piles

Steel pipe piles shall consist of steel pipe that conform to the Contract plans. Steel pipes for such
piles shall have an outside diameter and a minimum nominal wall thickness as shown in the Contract
documents.

Ends of closed-end pipe piles shall be closed with a flat plate, a forged or cast steel conical point, or
another end closure design that has been approved by the Engineer. End plates shall be at least 20
mm thick. The Contractor shall cut each end plate flush with its outer pile wall. They shall bevel the
end of each pipe before welding it to the end plate using a partial penetration groove weld. Larger
diameter pipes may require thicker end plates, thicker reinforcement, or both.

Before the Contractor places concrete into a pile, they shall use an acceptable inspection method to
confirm that the pile’s length and pile’s bottom is dry. If accumulations of water in pipes are present,
the Contractor shall remove all water before placing concrete.

Concrete for concrete-filled pipe piles shall be of class C20/20 and have a compressive strength of
at least 20.0 MPa and a slump from 150 mm to 250 mm.

For each pile, the Contractor shall place concrete in a single continuous operation.

The Contractor shall not place concrete in a pile until completing all pile driving within 4.5 metres of
that pile. Alternatively, after pouring concrete for a pile, the Contractor shall discontinue all pile driving
within 4.5 metres of that pile for at least two days and until concrete in such pile has completely set.

18.3.1.3

Painting

Unless otherwise provided, when steel piles or steel pile shells extend above the ground surface or
ground water level, they shall be protected by the paint system specified for painting steel piles as
described in Section 24.5 of Chapter 24, Painting, of the

Standard Specifications

This protection shall extend from an elevation 600 mm below the low water or ground level to the
top of the exposed steel

18.3.2

Pre-stressed Concrete Piles

Production of piles shall comply with Pre-stressed Concrete Institute (PCI) standards as outlined in
their

Manual for Quality Control for Plants and Production of Structural Precast Concrete Products

(MNL-116).

18.3.2.1

Forms for Pre-stressed Concrete Piles

Forms for pre-stressed concrete piles shall conform to the applicable requirements of Section 1.20.8
of Chapter 1, General Requirements, and Article 21.13.3.1of Chapter 21, Concrete Structures, of
the

Standard Specifications

and as provided in the PCI

’s

Manual for Quality Control for Plants and

Production of Structural Precast Concrete Products

(MNL-116).

18.3.2.2

Casting for Pre-stressed Concrete Piles

Concrete shall be cast continuously within three days after pretensioning steel; concrete shall not,
however, be cast in forms until

a quality control representative from a pile’s manufacturer has

inspected and approved the placement of reinforcement and anchorages. Each pile shall have dense
concrete surfaces that are straight and smooth. During fabrication, each pile shall have
reinforcement retained in its proper position. Unless the Contractor uses self-consolidating concrete,
they shall compact the concrete by vibrating it with a vibrator head that is smaller than the minimum

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distance between the pretensioning steel. A pile

’s end surfaces shall be perpendicular to its

longitudinal axis.

18.3.2.3

Finish for Pre-stressed Concrete Piles

Each pile’s finish shall comply with the PCI’s Manual for Quality Control for Plants and Production of
Structural Precast Concrete Products (MNL-116).

With standard finishing, a pile’s formed sides shall be reasonably smooth from casting against
approved forms. Standard finish for a pile’s top shall be a float finish with tooled edges.

18.3.2.4

Curing and Protection for Pre-stressed Concrete Piles

Curing of piles shall comply with PCI MNL-116, Manual for Quality Control for Plants and Production
of Structural Precast Concrete Products.

Piles shall be cured using moist curing or accelerated steam curing.

No pile shall be driven until it is sufficiently cured to resist handling and driving stresses without
damage.

18.3.2.5

Pre-stressing for Concrete Piles

Pre-stressing of piles shall comply with PCI

’s Manual for Quality Control for Plants and Production

of Structural Precast Concrete Products (MNL-116).

18.3.2.6

Shop Drawings for Pre-stressed Concrete Piles

The Contractor shall submit the required number of shop drawings for pre-stressed concrete piles to
the Engineer. Shop drawing shall indicate pile dimensions, materials, tendon arrangements, and pre-
stressing forces proposed for use, as well as any changes to reinforcing steel from that shown in the
Contract documents. Construction of the piles shall not begin until the Engineer has approved the
shop drawings.

18.3.2.7

Storage and Handling for Pre-stressed Concrete Piles

When handling, storing, and transporting pre-stressed concrete piles, the Contractor shall avoid
excessive bending stresses, cracking, spalling, or other injurious result.

18.3.2.8

Protective Coating for Pre-stressed Concrete Piles

If Contracts Documents indicate that protection is required, the Contractor shall apply protective
coating as specified in these specifications. The Contractor shall be responsible for restoring and
repair any damage to the coating.

18.4

Piles Driving

The Contractor shall comply with the specifications in this section when driving piles.

18.4.1

Pile Driving Equipment

The Engineer shall approve all pile driving equipment, including the pile driving hammer, hammer
cushion, helmet, pile cushion, and other appurtenances, before the Contractor conducts any pile
driving. Pursuant to obtaining this approval, the Contractor shall submit descriptions of all pile driving
equipment to the Engineer at least two weeks before pile driving is to begin. Such descriptions shall
contain sufficient detail to enable the using wave equation analysis to evaluate the proposed driving
system.

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If the nominal resistance is to be determined by static load test, dynamic test, quick static load test,
or wave equation analysis, the Contractor shall submit the results of a wave equation analysis to the
Engineer. Such analysis shall verify that the piles are drivable.

If the nominal resistance is to be determined by dynamic formula, a wave equation analysis is not
required. A required blow count, as determined by the dynamic formula, shall not exceed 120 blows
per 300 mm.

The Contractor shall use the hammer efficiencies shown in Table 18-2 in a wave equation analysis
of vertical piles, unless better information is available.

Table 18-2: Hammer efficiencies

Hammer type

Efficiency

Single-acting air/steam

67%

Double-acting air/steam

50%

Diesel

80%

Hydraulic or diesel with built-in energy measurement

95%

Hammer efficiencies shall be adjusted for batter driving.

In addition to the other requirements and specifications outlined in this chapter, the Contractor and
the Engineer shall use the following criteria to evaluate the driving equipment shall consist of both
the required number of hammer blows per 300 mm at the required nominal resistance and the pile
driving stresses over the entire driving process.

A driving system, as indicated by a wave equation analysis at the required nominal resistance, shall
require from 24 to 120 hammer blows per 300 mm. The Engineer shall not accept a system that
requires fewer or more hammer blows per 300 mm.

In addition, pile stresses, as determined by a wave equation analysis for the entire driving operation,
shall not exceed the following values:

1. For steel piles, compressive driving stress shall not exceed 90 percent of the yield point of

the pile material.

2. For concrete piles, tensile stresses shall not exceed 0.25 multiplied by the square root of the

concrete cube compressive strength (

f′c), in MPa, plus the effective pre-stress value, as

shown in Equation 18-1. Compressive stresses, also in MPa, shall not exceed 85% of the
cube compressive strength minus the effective pre-stress value, as shown in Equation 18-2.

•

Tensile stress = 0.25 √f

′

c + Prestress

Equation 18-1: Tensile stress

•

Compressive stress = 0.85 (f

′

c) − Prestress

Equation 18-2: Compressive stress

During pile driving operations, the Contractor shall use the approved system. The Engineer shall
consider changes to the driving system only after the Contractor has submitted revised pile driving
equipment data and wave equation analysis. The Engineer shall notify the Contractor of their
acceptance or rejection of proposed changes to a driving system within seven calendar days after
receiving a requested change. Time required for the submission, review, and approval of a revised
driving system shall not constitute grounds for a time extension for the Contract

or’s work.

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The Engineer

’s approval of pile driving equipment shall not relieve the Contractor of responsibility to

drive piles, free of damage, to the required nominal resistances and to any specified minimum
penetrations, as shown in the Contract documents.

18.4.1.1

Hammers for Pile Driving

Piles shall be driven with an impact or vibratory hammer that conforms to the specifications outlined
in this section. Pile driving hammers shall be of the size needed to develop the energy required to
drive the piles at a blow count that does not exceed 120 blows per 300 mm at the required nominal
resistance.

Drop Hammers for Pile Driving

The Contractor shall not use drop (gravity) hammers for concrete piles or for piles whose required
nominal resistance exceeds 60.0 tons.

Where the Project permits the use of drop hammers

, a drop hammer’s ram shall have a weight of at

least 10.0 kN

and drop heights shall not exceed 3.6 metres. A drop hammer’s ram weight shall never

be less than the combined weight of a helmet and a pile. All drop hammers shall have hammer
guides and a helmet to ensure concentric impact.

Air Hammers for Pile Driving

If the Contractor uses a dynamic formula to establish the required blow count, the weight of the
striking parts of air hammers used shall not be less than one-third the weight of a pile and its drive
cap, and an

air hammer’s striking part shall weigh at least 14.0 kN. If the Contractor uses a wave

equation analysis to establish the required blow count and driving stresses, this limitation on ram
weight shall not apply.

Plant and equipment for air hammers shall have sufficient capacity to maintain, under working
conditions, the pressure specified for the hammer by its manufacturer. A hose that connects a
compressor to an air hammer shall be at least the minimum size recommended by the

air hammer’s

manufacturer.

Upon using an air hammer to drive a pile, the Contractor shall evaluate the hammer

’s performance

by measuring blows per minute and comparing these blows to the m

anufacturer’s recommendations.

Diesel Hammers for Pile Driving

If open-end (single-acting) diesel hammers are not equipped with a device to measure impact
velocity at all times during pile driving operations, the Contractor shall obtain the stroke by measuring
the speed of operation either manually or with a device that takes the measurement automatically.

Closed-end (double-acting) diesel hammers shall have a bounce chamber pressure gauge in good
working order, mounted near ground level to enable the Engineer to read it easily. The Contractor
shall provide a correlation chart of bounce chamber pressure and potential energy.

Hydraulic Hammers for Pile Driving

Hydraulic hammers shall have a system for measuring ram energy. Such systems shall be in good
working order and make their results easily and immediately available to the Engineer.

Vibratory Hammers for Pile Driving

Vibratory or other pile driving methods may be used only when specified in the Contract documents
or when approved in writing by the Engineer. Except when pile lengths have been evaluated from
static load test piles, the Contractor shall verify that vibratory hammers are driving piles to their
nominal resistances. Upon driving a group of ten piles with a vibratory hammer, the Contractor shall
use an impact hammer that can measure nominal resistance to further drive the first pile in that
group. If piles reside in different soils, the Contractor shall apply the impact hammer to additional

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piles, as directed by the Engineer. The Contractor shall use an impact hammer to complete driving
for any pile that relies primarily on point bearing capacity.

The Contractor shall not use vibratory hammers to drive concrete piles.

Additional Equipment or Hammering Methods for Pile Driving

If none of the hammers outlined in previous sections obtains the required penetration, the Engineer
may require that the Contractor provide a hammer of greater energy or to use supplemental
methods, such as jetting or predrilling, as described in Article 18.4.1.2.

18.4.1.2

Pile Driving Appurtenances

Pile driving appurtenances shall comply with the specifications outlined in this section.

Hammer Cushions for Pile Driving

All impact pile driving equipment shall include a hammer cushion that is sufficiently thick to prevent
damage to the hammer or pile. Drop hammers and any hammers whose design specifically avoids
the need for a hammer cushion shall be exempt from this requirement.

Where  applicable,  hammer  cushions  shall  durable,  manufactured  material  that  retains  uniform
properties during driving. Such cushions shall not be wood, wire rope, or asbestos. A striker plate
on each hammer cushion shall ensure that the cushion material compresses uniformly. Before using
a  hammer  for  driving,  the  Contractor  shall  replace  any  hammer  cushion  that  wear  has  reduced
original thickness by 25% or more. For air hammers, the Contractor shall comply with the hammer
manufacturer’s recommendations for replacing worn cushions before use.

Helmets for Pile Driving

Piles driven with impact hammers shall include a helmet that distributes

the hammer’s blows

uniformly and concentrically to the pile

’s head. A helmet’s surface that contacts a pile shall be plane

and smooth and shall be parallel with the hammer base and the pile

’s top. Such helmet’s shall be

guided by leads, rather than free-swinging. Such helmets shall fit pile heads in a manner that
maintains concentric alignment between the hammer and a pile.

For special types of piles, appropriate driving heads, mandrels, or other devices shall be provided
so that the piles may be driven without damage.

Pile Cushions for Concrete Piles

A pile cushion shall protect the head of each concrete pile. To determine how thick such cushions
should be to prevent excessive driving stresses, the Contractor shall apply wave equation analysis.
If the Contractor uses a dynamic formula to determine the required driving blow count, such cushions
shall be at least 100 mm thick.

While using a hammer for concrete piles, If a pile cushion begins to smoke or excessive compression
occurs, the Contractor shall replace the cushion. A pile cushion

’s dimensions shall distribute hammer

blows uniformly over

a pile’s entire cross-section.

Hard driving conditions may require frequent cushion replacement, perhaps before finishing even a
single pile. In easy driving conditions, however, each pile cushion may last through several piles.

Pile cushions shall be protected from the weather and kept dry before use. Pile cushion shall not be
soaked in any liquid unless the Engineer approves such action. The Contractor may ask the Engineer
to approve the use of manufactured pile cushion materials rather than wood pile cushions on a case-
by-case basis.

For restrike tests, the Contractor shall use a used pile cushion that is still in good condition.

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Leads for Pile Driving

Throughout a pile driving operations, the Contractor shall use leads that properly align each pile with
a  hammer  to  ensure  that  each  blow  strikes  with  concentric  impact.  Such  leads  shall  not  impede
hammer  movement.  As  applicable,  they  shall  permit  proper  alignment  of  battered  piles.  The
Contractor may use either fixed or swinging leads. Swinging leads shall include a pile gate at their
bottom  ends.  To  maintain  alignment  between  leads  and  piles,  the  Contractor  shall  either  embed
each lead adequately in the ground or use a structural frame, such as a template, to constrain each
pile.

Followers for Pile Driving

The Contractor shall use followers only when the Engineer approves such use in writing or when the
Contract documents specify such use.

When using followers for a concrete pile, the Contractor shall attach a pile cushion to the top of a
concrete pile. To ensure that followers are suitable for a concrete pile, the Contractor shall conduct
a wave equation analysis to verify blow count, driving stresses, and nominal resistance.

If the Contractor does not use a wave equation analysis to determine impedance for a steel pile,
they shall use a follower with an impedance between 50% and 200% of the steel pile

’s impedance.

The Contractor shall apply a wave equation to check piles that are driven with a follower. They shall
test piles with either a static test or dynamic test on the pile, on the follower, or both. Such testing
eliminates the need to drive a longer full length test pile in each footing.

A follower and pile shall be maintained in proper alignment during driving. A follower shall be of such
material and dimensions to permit piles to be driven to the necessary blow count.

After driving a pile with a follower, the Contract

or shall verify a pile’s final position by checking the

position and inclination of the follower.

Jetting for Pile Driving

The Contractor shall use jetting only when the Engineer approves such use in writing or when the
Contract documents specify such use.

The Contractor shall determine the number of jets and the volume and pressure of water at the jet
nozzles that is necessary to freely erode material that is adjacent to a pile.

The Contractor shall control and dispose of all jet water in a manner that is satisfactory to the
Engineer or as specified in the Contract documents. The Contractor shall be responsible for all
damages to the site caused by their jetting operations.

Unless otherwise indicated by the Engineer or the Contract documents, the Contractor shall remove
jet pipes before or when a pile

’s tip is 1.5 metres above the minimum or final tip elevation. The

Contractor shall then drive the pile without jetting to the final tip elevation or to the required nominal
resistance with an impact hammer. If the required nominal resistance is not reached at the final tip
elevation, the Contractor may allow a pile to set up then determine the required nominal resistance
by restriking the pile.

18.4.2

Preparation for Pile Driving

When preparing for pile driving, the Contractor shall comply with the specifications outlined in this
section.

18.4.2.1

Preparation for Site Work

When conducting pile driving work on the Project site, the Contractor shall comply with the
requirements outlined in this section.

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Excavation for Pile Driving

If practical, piles shall not be driven until after the excavation is complete. Before placing concrete
for a foundation, the Contractor shall remove any material that has been forced up between piles
until surrounding ground is the correct elevation.

Unless otherwise approved by the Engineer, piles at bridge ends shall not be driven until roadway
embankments are placed.

Predrilling to Facilitate Pile Driving

When  the  Contract  documents  require  predrilling,  the  Contractor  shall  predrill  holes  of  a  size
specified,  at  pile  locations,  and to the  depths  shown  in  the  Contract  documents  or  as  directed  in
writing by the Engineer.

Predrilling is usually used in the case where driving a pile will displace the upper soil enough to push
adjoining piles out of the proper position or to limit vibration in the upper layers.

Normally, predrilled holes are smaller than the diameter or diagonal of a pile

’s cross-section and

sufficient to allow penetration of a pile to its specified elevation. If the Contractor encounters
subsurface obstructions, they may increase a hole

’s diameter to the least dimension necessary to

avoid obstructions and install piles.

If, after pile driving, void spaces remain around a pile, the Contractor shall fill them with sand or other
approved material. The Contractor cannot use spuds rather than predrilling, unless the Contract
documents or the Engineer, in writing, approves such use. Material resulting from drilling holes shall
be disposed of as approved by the Engineer.

Additional Requirements for Pre-drilled Holes in Embankments

If required by the Contract documents, piles to be driven through compacted fill or embankment of a
depth greater than 1.5 m shall be driven in holes predrilled to natural ground. A predrilled hole should
have a diameter not more than the greatest dimension of the pile cross-section plus 150 mm. After
the Contractor drives a pile, they shall fill the space around the pile to the ground surface with sand
or other approved material. Material resulting from predrilling holes shall be disposed of as approved
by the Engineer.

18.4.2.2

Preparation for Piling

Pile Heads

For steel piling, pile heads shall be cut and maintained square to the longitudinal axis of the pile.
Precast concrete pile heads shall be flat, smooth, and perpendicular to the longitudinal axis of a pile
to prevent eccentric impacts from a helmet. Pre-stressing strands shall be cut off below the surface
of the end of the pile. For concrete piles, a pile

’s head shall be chamfered on all sides. Pre-stressed

concrete piles may also be chamfered along their length.

A pile’s prepared head shall provide uniform contact and thereby reduce the potential of damage to
the pile

’s top. Before assessing blow count acceptance, based on driving criterion, the Contractor

shall

remove any distortions from a pile’s top.

Pile Shoes and End Plates

Pile shoes shall be used when specified by the Engineer or in the Contract documents to protect all
types of piles when hard driving or obstructions are expected.

Steel pile shoes shall be grade 90-60 cast steel that conforms to

ASTM’s

Standard Specification for

Steel Castings, High Strength, for Structural Purposes

(ASTM A148/A148M).

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End plates used on closed-end pipe piles shall be made of steel that complies with or exceeds
ASTM’s

Standard Specification for Carbon Structural Steel

(ASTM A36/A36M).

A steel plate’s

diameter and thickness shall be specified by the Engineer.

A pile driving acceptance criterion should be developed that will prevent damage to the pile toe. Steel
piles driven into soft rock may not require toe protection.

When hard rock, sloping rock, or obstructions are expected, a pile toe should be protected with cast
steel shoes.

Pile shoes used at the option of the Contractor shall be of a type approved by the Engineer.

18.4.3

Performing Pile Driving

Unless the Engineer approves alternatives, the Contractor shall drive piles to their required nominal
resistances and to either their minimum tip elevation or a specified alternative tip elevation.

The Contractor shall always count the hammer blows required to drive a pile, either during initial
driving or when driving a pile again with a warm hammer after a wait period, as determined by the
Engineer.

For diesel hammers, the Contractor shall record strokes. For hydraulic hammers, the Contractor
shall record either energy or impact velocity.

If the Contractor uses water jets are in conjunction with pile driving, they shall determine the nominal
resistance from the results of driving after withdrawing the jets.

A pile driving procedure shall not subject piles to excessive and undue abuse and shall not result in
crushing and spalling of the concrete, injurious splitting, splintering, or excessive deformation of
steel.

18.4.3.1

Driving Heaved Piles

If piles heave, the Engineer shall take level readings referenced to a fixed datum on all piles
immediately after their installation and periodically thereafter as adjacent piles are driven to
determine the range of pile heaving.

The Contractor shall drive a pile again if the driving process for adjacent piles results in either of the
following conditions:

a. Piles heave more than 12.0 mm and end bearing is dominant
b. Piles heave more than 40.0 mm and shaft friction is dominant

If pipe or shell piles that have been filled with concrete heave, the Contractor shall drive such piles
again to their original positions after the concrete has obtained sufficient strength, using a proper
hammer-pile cushion system that the Engineer deems satisfactory.

18.4.3.2

Pile Installation Sequence

The Contractor shall install piles within a pile group sequentially, either starting from the centre of a
group and proceeding outward in both directions or starting at the outside row and proceeding
progressively across the group.

18.4.3.3

Practical Refusal for Pile Driving

A pile reaches a level of practical refusal when resistance to penetration makes driving a pile deeper
impractical. A practical refusal blow count for a pile depends on the site

’s soil profile and the pile’s

type, and may possible be limited by the hammers used, in accordance with the hammer
manufacturer

’s published limitations to prevent hammer damage. In no case shall driving continue

for more than 75 mm after a pile reaches practical refusal conditions.

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18.4.3.4

Limiting Pile Driving Stresses

Unless the Contract documents or the Engineer specify otherwise, stresses induced during driving
shall not exceed the limits set forth in Section 18.4.1.

18.4.3.5

Driving Probe Piles

Where required in the Contract documents, probe piles shall be furnished to the lengths specified
and driven at the locations and to the elevations, nominal resistances, or blow counts directed by
the Engineer before other piles are ordered. All piles shall be driven with approved impact hammers
unless the Contract documents specifically state otherwise. The Contractor shall use hammers of
the same type and size on production piles.

Unless the Engineer approves an alternate approach, the Contractor shall excavate the ground at
each probe pile to the elevation of the bottom of the footing before driving a pile. Additional probe
piles shall be driven at locations selected by the Engineer to explore possible subsurface variations.

When the Engineer so orders, the Contractor shall drive probe piles to plan grade. If any probe pile
fails to attain required nominal resistance, the Contractor shall splice that probe pile and drive it
further until it attains the required bearing.

Any  probe  piles  that  do  not  attain  the  required  hammer  blow  count  or  that  fail  to  attain  nominal
resistance at the specified depth may be allowed to  set for 12 to 24 hours, as determined by the
Engineer,  before  the  Contractor  drives  them  again. If  a  probe  pile still fails  to  attain  the  specified
nominal resistance after it is driven again, the Engineer may direct the Contractor to drive a portion
or all of the remaining probe pile and repeating the process of setting up and driving the pile.

18.4.3.6

Accuracy of Pile Driving

Piles shall be driven with a variation of not more than 1:50 from the vertical or not more than 1:25
from the batter shown in the Contract documents. Piles for trestle bents, however, shall be driven so
that the cap may be placed in its proper location without adversely affecting the resistance of the
piles.

After driving, a pile

’s head shall be within 150 mm of plan locations for all piles capped below final

grade, and shall be within 75 mm of plan locations for bent caps supported by piles,

No pile shall be nearer than 100 mm from any edge of the cap. Any increase in pile cap dimensions
or reinforcing caused by out-of-position piles shall be at the Contract

or’s expense.

The Contractor shall make every effort to install piles at the planned location and at the planned
batter, unless deviations occur due to existing obstructions.

18.4.4

Determination of the Nominal Resistances for Piles

To determine  the nominal resistances for  piles, the  Engineer will  use the method specified in the
Contract documents. Any method used to determine resistance of piles during or after installation
shall  be  consistent  with  the  pile  resistance  verification  methodology  assumed  during  the  Project
design  phase,  in  accordance  with  Article  10.5.5.2.3  of  the

AASHTO LRFD Bridge Design

Specifications

Consideration should be given to the potential for change in nominal resistance after the end of
driving. Effects of soil relaxation and setup should be considered in the determination of nominal
resistance for soils that are likely to be subject to these phenomena. Such cases may require a wait
period to allow for gain due to setup, with confirmation of the nominal resistance by a retest (static
or dynamic).

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18.4.4.1

Static Load Tests

If a static load test is used to determine a pile

’s axial resistance, such test shall not be performed

less than five days after a test pile was driven unless the Engineer or the Contract documents direct
otherwise.

Each static load test shall follow the procedures specified in

ASTM’s

Standard Test Methods for

Deep Foundations Under Static Axial Compressive Load

(ASTM D1143/D1143M), Section 17.16 of

Chapter 17, Drilled Piles, of the

Standard Specifications

and the loading procedure shall follow the

Quick Load Test Method, unless detailed longer-term load-settlement data are needed, in which
case the standard loading procedure should be used. Testing equipment and measuring systems
shall also conform to ASTM D1143/D1143M.

The Contractor shall submit detailed documents of the proposed loading apparatus to the Engineer
for approval. Such submittals shall include calibrations for the hydraulic jack, load cell, and pressure
gauge conducted within 30 days before mobilization to the job site. When the approved method
requires the use of tension (anchor) piles that will later be used as permanent piles in the work, such
tension piles shall be of the same type and size as the production piles and shall be driven in the
location of permanent piles where feasible.

While  performing  a  static  load  test,  the  Contractor  shall  provide  safety  equipment  and  employ
adequate  safety  procedures.  Adequate  support  for  the  static  load  test  plates,  jack,  and  ancillary
devices  shall  be  provided  to  prevent  them  from  falling  in  the  event  of  a  release  of  load  due  to
hydraulic failure, test pile failure, or other cause.

pile’s nominal resistance may increase (as soil sets up) or decrease (as soil relaxes) after driving

ends. Therefore, the Contractor shall perform a static load after equilibrium conditions in the soil are
re-established; such testing is essential.

Based on the type of soil and ground that piles shall penetrate, the Contractor shall allow a sufficient
delay between pile driving and load testing, as follows:

a. Piles driven into clays: Delay two weeks

b. Weathered shale: Delay seven days

c. Sandy silts or sands: Delay five to seven days

The Contractor shall use the method for defining failure of the static load test that is defined in the
Contract documents or by the Engineer. Based on the static load test results, the Engineer shall
provide the driving criteria for production pile acceptance.

Tension static load tests shall be ducted in accordance with

ASTM’s

Standard Test Methods for

Deep Foundations Under Static Axial Tensile Load

(ASTM D3689). Lateral load tests shall be

conducted in accordance with

ASTM’s

Standard Test Methods for Deep Foundations Under Lateral

Load

(ASTM D3966).

18.4.4.2

Dynamic Testing

Dynamic testing shall be conducted in accordance with

ASTM’s

Standard Test Method for High-

Strain Dynamic Testing of Piles

(ASTM D4945). The Contractor shall prepare for the required

instrument attachment as directed by the Engineer.

The Contractor shall drive piles for dynamic testing as directed by the Engineer. If the Engineer so
directs, the Contractor shall reduce the driving energy transmitted to the pile by using additional
cushioning or reducing the energy output of the hammer to maintain acceptable stresses in the piles.

If dynamic measurements indicate non-axial driving, the Contractor shall immediately realign the
driving system.

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If the required nominal resistance is not achieved at the end of driving, the Contractor shall restrike
the dynamic test pile following a waiting period specified in the Contract documents or as directed
by the Engineer.

After the waiting period, the Contractor shall reattach the dynamic testing instruments, drive the test
pile again, and repeat the dynamic test. Before striking a test pile again, the Contractor shall allow a
hammer to warm up. The Contractor shall stop driving a test pile either upon reaching a depth of
75mm or after delivering 20 blows, whichever occurs first.

18.4.4.3

Wave Equation Analysis

When specified in the Contract documents, the Engineer shall use a wave equation analysis to
determine the driving criterion necessary to reach

a pile’s required nominal resistance. Soil and pile

properties to be used in this analysis shall be as shown in the Contract documents or as determined
by the Engineer. The Contractor shall provide the information on proposed driving equipment that
the Engineer needs to perform the wave equation analysis.

18.4.4.4

Dynamic Formula

The Contract documents shall specify the particular dynamic formula to be used, if any. The
Contractor shall not use a dynamic formula if the required nominal resistance is more than 2,700 kN.

Formulas shall be considered applicable only where the head of the pile is not crushed, or otherwise
damaged, and a follower is not used.

If a dynamic formula is used to establish the driving criterion, the FHWA Gates Formula specified in
this chapter should be used. During driving, the Contractor shall use Equation 18-3 to measure
nominal pile resistance.

ndr

= 1.75

√Ed

log

(10N

) − 100

Equation 18-3: Dynamic Formula

Where:

ndr

Nominal pile resistance measured during pile driving (kips)

Ed = Developed hammer energy. This is the kinetic energy in the ram at impact for a given blow.
If ram velocity is not measured, it may be assumed equal to the potential energy of the ram at the
height of the stroke, taken as the ram weight times the stroke (ft-lbs)

Number of hammer blows for 1.0 in. of pile permanent set (blows/in.)

If the Contractor uses a dynamic formula other than those provided in this chapter, the Contractor
shall calibrate the formula based on measured static load test results to obtain an appropriate
resistance factor, in accordance with article C10.5.5.2 of the

AASHTO LRFD Bridge Design

Specifications

18.4.5

Splicing Piles

Where splices are unavoidable for steel or concrete piles, their number, locations, and details shall
be subject to the Engineer

’s approval.

18.4.5.1

Splicing Steel Piles

Full-length piles shall be used where practicable. If splicing is permitted, the method of splicing shall
be approved by the Engineer. Either shielded arc or submerged arc welding should be used when

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splicing steel piles. Only certified welders shall perform welding. Mechanical splices that are not
welded shall be used for compression piles only.

18.4.5.2

Splicing Concrete Piles

Full-length piles shall be used where practical. Where splicing is permitted, concrete pile splice
details shall conform to the Contract documents, or as approved by the Engineer. Mechanical
splices, including drive-fit splices, may also be used.

18.4.6

Defective Piles

A pile-driving procedure shall not subject them to excessive and undue abuse or produce crushing
and spalling of the concrete, injurious splitting, splintering, or excessive deformation of steel.
Manipulation of piles to force them into proper position, considered by the Engineer to be excessive,
shall not be permitted. At his own expense, the Contractor shall take action to correct any pile that
has damage resulting from internal defects or improper driving. At his own expense, the Contractor
shall also correct any piles that have been driven out of its proper location or below the butt elevation
(as determined in the Contract documents or by the Engineer). The Contractor shall use one of the
following methods, as approved by the Engineer, to make such corrections:

•

If practicable, the Contractor shall withdraw a defective pile and replace it with a new one,

which may need to be longer than the defective pile being replaced.

•

The Contractor shall drive one or more replacement piles that are adjacent to the defective

pile.

To correct a pile that has been driven below the specified butt elevation, the Contractor shall use
one of the following methods, as approved by the Engineer:

•

The Contractor shall splice and build up the pile in accordance with the specifications outlined

in this chapter.

•

The Contractor shall extend a sufficient portion of the footing downward to properly embed

the pile.

To correct a pile that has been driven out of its proper location, the Contractor shall use one of the
following methods, as approved by the Engineer:

•

The Contractor shall drive one or more replacement piles next to the pile that is out of

position.

•

The Contractor shall extend the footing laterally to incorporate the pile that is out of position.

•

The Contractor shall add additional reinforcement.

The Contractor shall provide all such remedial materials and work at his own expense.

18.4.6.1

Pile Cut-Off

The Contractor shall cut all piles to a true plane at the required elevations and anchor them to the
structure as shown in the Contract documents. All cut-off lengths of piling shall remain the property
of the Contractor, who shall dispose of them properly.

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NDEX

blow count, 18-1, 18-5, 18-6, 18-8, 18-10, 18-

Concrete, 18-3, 18-4, 18-8, 18-1
cracking, 18-4
cut-off lengths, 18-2
diesel hammers, 18-6, 18-10
drop hammers, 18-6
Dynamic testing, 18-13
followers, 18-8
hammer blows, 18-1, 18-5, 18-8, 18-10, 18-1
hammer cushion, 18-5, 18-7
hammer efficiencies, 18-5
helmet, 18-5, 18-6, 18-7, 18-10
Hydraulic hammers, 18-7
impedance, 18-8
jetting, 18-7, 18-8, 18-9

nominal resistances, 18-1, 18-6, 18-7, 18-
10, 18-11, 18-12

paint system, 18-3
pile heads, 18-7, 18-10
practical refusal, 18-11
predrilling, 18-7, 18-9
pre-stressed, 18-3, 18-4
pretensioning steel, 18-3
protection, 18-3, 18-4, 18-10
spalling, 18-4, 18-10, 18-1
splices, 18-1
static load test, 18-5, 18-7, 18-12, 18-13, 18-1
steel piles, 18-2, 18-3, 18-5, 18-1
ultimate capacity, 18-1
vibratory hammer, 18-6, 18-7
wave equation analysis, 18-5, 18-6, 18-8, 18-

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Chapter 19: Ground Anchors

ABLE OF

ONTENTS

Table of Contents

........................................................................................................................... i

List of Tables .................................................................................................................................. ii

Ground Anchors .............................................................................................................. 19-1

19.1

Ground Anchor Terminology ........................................................................................ 19-1

19.2

Reference Standards and Codes ................................................................................. 19-2

19.3

Working Drawings for Ground Anchor .......................................................................... 19-3

19.4

Materials for Ground Anchor ........................................................................................ 19-4

19.4.1

Prestressing Steel for Ground Anchor ................................................................... 19-4

19.4.2

Grout for Ground Anchor ...................................................................................... 19-4

19.4.3

Steel Elements for Ground Anchor........................................................................ 19-4

19.4.4

Corrosion Protection Elements for Ground Anchor ............................................... 19-5

19.4.5

Miscellaneous Elements for Ground Anchor ......................................................... 19-5

19.5

Fabrication of Ground Anchor ...................................................................................... 19-6

19.5.1

Tendon Bond Length for a Ground Anchor ........................................................... 19-6

19.5.2

Spacers and Centralisers for a Ground Anchor ..................................................... 19-6

19.5.3

Tendon Unbonded Length for a Fround Anchor .................................................... 19-6

19.5.4

Anchorage and Trumpet for a Ground Anchor ...................................................... 19-7

19.5.5

Tendon Storage and Handling .............................................................................. 19-7

19.6

Installation of a Ground Anchor .................................................................................... 19-7

19.6.1

Drilling for Anchor Installation ............................................................................... 19-7

19.6.2

Tendon Insertion for Anchor Installation ................................................................ 19-7

19.6.3

Grouting for Anchor Installation ............................................................................. 19-8

19.6.4

Trumpet and Anchorage for Anchor Installation .................................................... 19-8

19.7

Testing and Stressing for a Ground Anchor ................................................................. 19-8

19.7.1

Equipment for Ground Anchor Testing .................................................................. 19-9

19.7.2

Performance Testing for Ground Anchors ............................................................. 19-9

19.7.3

Proof Testing for Ground Anchors ...................................................................... 19-11

19.7.4

Creep testing for Ground Anchors ...................................................................... 19-12

19.7.5

Acceptance Criteria for Ground Anchor Testing .................................................. 19-13

19.7.6

Lock-Off .............................................................................................................. 19-14

Index

....................................................................................................................................... 19-15

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GROUND ANCHORS

This chapter outlines standards and requires with which the Contractor shall comply with when
designing, furnishing, installing, testing, and stressing permanent cement-grouted ground anchors.
Such work shall also comply with the Contract documents.

Structural systems ground anchors have the following typical applications:

•

Retaining structure tie backs

•

Resisting uplift forces

•

Serving as tension foundations

•

Stabilising slopes

•

Underground structures

•

Soil nailing (bar type anchors)

•

Securing base slabs

•

Securing basins

19.1

Ground Anchor Terminology

The listed terminologies are specific to works related to ground anchors chapter only.

Alignment Load (AL): A nominal minimum load applied to an anchor during testing to keep testing
equipment positioned correctly.

Anchor Devices:

Wedges or nuts that grip prestressing steel.

Anchor Head: A device by which prestressing force is permanently transmitted from the prestressing
steel to the bearing plate.

Anchorage:

A system that combines an anchor head, bearing plate, trumpet, and anchorage

corrosion protection to transmit the prestressing force from the prestressing steel to the surface of
the ground or the supported structure.

Bearing Plate: A steel plate that evenly distributes ground anchor force to the main structure.

Bond Tendon Length: Length of the ground anchor that is bonded to the ground and that transmits
tensile force to the soil or rock.

Centraliser:

A device that supports and positions the tendon in the drilled hole to maintain grout

cover.

Coupler:

A means to transmit prestressing force from one partial-length of prestressing tendon

to another.

Design Load (DL):

An anchor’s anticipated maximum effective load after allowing for time-

dependent losses or gains.

An anchor’s design load incorporates appropriate factors to ensure that

the overall structure has adequate capacity for its intended use.

Unbounded Length: Design length for a tendon that is not bonded to the surrounding ground or
grout during stressing.

Ground Anchor:

A system, as also called a tieback, that transfers tensile loads to soil or rock.

A ground anchor includes all prestressing steel, anchorage devices, grout, coatings, sheathings, and
any couplers that are used.

Lift-Off Load: A tendon

’s load, as checked by lifting its anchor head off a bearing plate with a

hydraulic jack.

Lock-Off Load:

Prestressing force in an anchor immediately after transferring load from a jack

to stressing anchorage.

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