CONTENTS
1. INTRODUCTION
2. C4-10 BORED PILING
3. C4-20 DRIVEN PILING
4. C4-30 PILE TESTING
1 INTRODUCTION
This document presents the specifications for piling works to be used in the project. The specifications found
herewith shall supplement SCI’s
specification listed below and the Invitation to Bid (ITB) Appendix A: Facilities
Description / Scope of Work document. Unless noted otherwise,
the more onerous criteria or requirements specified between
SCI’s specification
and the ITB
Appendix-A document shall
take precedence over the conflicting clauses
found in this document.
SCI Specification & Standard
Document No.
|
Rev.
|
Document
Title
|
SUTO-ALL-C08-4-001
|
1
|
Specification
and Standard: Demolition
and Site Clearance
|
SUTO-ALL-C08-4-002
|
2
|
Specification
and Standard: Earthworks
and Excavation
|
SUTO-ALL-C08-4-003
|
1
|
Specification
and Standard: Piling
– Driven Piles
|
SUTO-ALL-C08-4-004
|
1
|
Specification
and Standard: Structural
Steelworks
|
SUTO-ALL-C08-4-005
|
1
|
Specification
and Standard: Soil
Investigation & Testing
|
SUTO-ALL-C08-4-006
|
1
|
Specification
and Standard: Concrete
|
SUTO-ALL-C08-4-008
|
1
|
Specification
and Standard: Pipe
Rack Design Criteria
|
In the event that the specifications are not available
in either the SCI’s or those found herewith,
refer to the latest edition of the National Productivity and Quality Specifications published by
SPRING Singapore. The specification list
is non-exhaustive and will be expanded if the need arise.
2 C4-10 BORED
PILING
CONTENTS
Page
|
1.
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GENERAL
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3
|
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1.1
|
Scope
|
3
|
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1.2
|
Related Sections
|
3
|
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1.3
|
Standards and Regulations
|
3
|
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1.4
|
Trade Preambles
|
4
|
|
1.5
|
Definitions
|
7
|
|
2.
|
PERFORMANCE REQUIREMENTS
|
8
|
|
2.1
|
Requirements
for Design Verification
|
8
|
|
2.2
|
Performance Criteria for Piles Under
Test
|
8
|
|
2.3
|
Permissible Damage Criteria for Existing Critical Structures or Services
|
8
|
|
3.
|
MATERIALS
|
9
|
|
3.1
|
Source of Materials
|
9
|
|
3.2
|
Drilling Fluid
|
9
|
|
3.3
|
Water
|
9
|
|
3.4
|
Concrete
|
9
|
|
3.5
|
Grout
|
9
|
|
3.6
|
Reinforcement
|
9
|
|
3.7
|
Temporary Casings
|
9
|
|
3.8
|
Permanent
Steel Casings
|
10
|
|
4.
|
WORKMANSHIP
|
11
|
|
4.1
|
General Workmanship Requirements
|
11
|
|
4.2
|
Trial Bores
|
11
|
|
4.3
|
Boring Excavation
|
11
|
|
4.4
|
Use of Drilling Fluid
|
13
|
|
4.5
|
Cleanliness of Pile Bases
|
13
|
|
4.6
|
Reinforcement
|
14
|
|
4.7
|
Pile Casting
|
14
|
|
4.8
|
Backfilling Empty Boring
|
17
|
|
4.9
|
Grouting of
Piles
|
17
|
|
4.10
|
Tolerances
|
18
|
|
4.11
|
Protection to
Piles
|
19
|
|
4.12
|
Replacement of Piles
|
19
|
|
4.13
|
Cleaning Up
|
19
|
|
4.14
|
Non-Performance of Working Piles
|
19
|
|
4.15
|
Cutting Off Pile Heads
|
19
|
|
4.16
|
Noise and Disturbance
|
20
|
|
4.17
|
Final Survey and As-Built Drawing
|
20
|
|
5.
|
VERIFICATION AND SUBMISSIONS
|
21
|
|
5.1
|
Submissions
|
21
|
|
5.2
|
Inspection and Test Certificates
|
22
|
|
5.3
|
Tests
|
23
|
|
5.4
|
Compliance Testing of
Drilling Fluid
|
23
|
|
5.5
|
Pile Testing
|
24
|
|
5.6
|
Records
|
25
|
. GENERAL
Read with the General Requirements section,
and
all other contract documents.
1.1 Scope
This section covers the requirements for the construction of bored cast-in-place piles including:
a. In-situ concrete piles b. Micro piles
The piles may be used as foundations to support principally vertical loads, or may be used
to form embedded
retaining walls resisting principally horizontal loads.
1.2 Related Sections
Read this work section in conjunction with the relevant requirements of the other work sections as follows:
C1-20 Condition Survey and Monitoring
C2-10 Site Investigations
C2-50 Instrumentation and Monitoring
C4-30 Pile Testing
C3-10 Concrete Construction Generally
C3-20 Reinforcement
1.3 Standards and Regulations
1.3.1 Standards
Unless otherwise agreed by the Superintending Officer (SO), ensure all of the
Works comply with the relevant requirements of the Standards and Codes listed below
or referenced in the body of the Specification. Alternative Standards and Codes may
be proposed for approval by the SO, provided it can be demonstrated
that
the alternative
Standards and Codes comply with the requirements of the standards specified. All
Standards and
Codes quoted
are the
current version, unless specific year references are
noted.
Singapore Standards
SS 31 Aggregates from
natural sources for concrete
SS 78: Part A16 Testing Concrete.
Method
of determination of
compressive strength of
concrete cubes
SS CP 4 Foundations
SS CP 65: Part 1 Structural use of concrete. Design and Construction
SS CP 79 Safety management system
for construction worksites
Other Standards
API SpecificationDrilling Fluid13A 5th Edition
API-RP-13B-1 2nd Standard procedure for field-testing water-based drilling fluid Edition BS 1305 Batch type concrete mixers
BS EN 1008 Mixing water for concrete, specification for sampling, testing
and assessing the suitability of water
BS 5228 Noise and vibration control on construction and open sites
Part 1(1997)
Code of
practice for
basic information
and
procedures for noise and vibration control
Part 4 (1992) Code of practice for noise and vibration control applicable to piling operation
BS 5930 Code of practice for site investigations
BS 7123 Metal arc welding of steel for
concrete reinforcement
BS 8004 Code of practice for foundations
BS 8008 Guide to safety precautions and
procedures for the
construction and descent of machine-bored shaft piling and
other purposes.
BS EN 1538 Execution of special geotechnical work – Diaphragm Walls
In the event that the standards or Codes are revised or superseded, refer to the latest edition or the appropriate substitution for
the
relevant subjects.
1.3.2 Technical Reference
Refer to the following technical reference for guidance in carrying out
the
works:
a. BRE Digest 251
(1995) Assessment of damage in low-rise building.
b. Construction Industry Research and Information Association, England (CIRIA) Report 104 (1984) Design of retaining wall embedded in stiff
clay.
1.4 Trade Preambles
1.4.1 Design Verification
Engage technically competent personnel with relevant geotechnical experience to SO’s acceptance, to carry out:
a. Verification
of
material
excavated at the intended pile founding level as consistent with the design requirements.
b. Design verification checks based on actual
ground conditions to determine the
required length of each pile and ensure that the specified working load and
settlement
criteria of
the
piles are achieved.
c. Proposals to amend the design including compensating piles as necessary in the
event that for any reasons the installed piles do not perform as intended.
d. Proposals to amend the pilecap design of the building in the event that the piles are installed out of
the
permitted tolerance.
e. Proposals as a response plan in the event that measures taken to control ground
movement and
vibration do not
perform satisfactorily.
Take into account
of the design requirements as set out in Clause
2.1 below.
Submit the design to the SO for acceptance. Design proposals in (c) to (d) are to be designed and endorsed by a PE (Civil).
Submit the CV of the personnel to be engaged for the above including the PE’s, for SO’s acceptance.
1.4.2 Building Damage Assessment
Carry out a Building Damage Assessment, if required by the project specification, on the
effects of ground movement to
the
neighboring properties due to
the works, for the purpose of
establishing suitable values for ‘Alert’ and “Work Suspension’ levels for
monitoring. Submit to SO with endorsement from a PE.
1.4.3 Coordination with Other Works
Co-ordinate with other
contractors who may carry out
other works at the same time at the
site. Take
into account of site access, space occupation, safety and safeguarding of
adjoining properties and each other’s works.
1.4.4 Condition Survey
Where applicable, prior to and upon completion of the site works, carry out a condition
survey to
adjacent buildings in
accordance
with
the requirements of
section C1-20 “Condition Survey and Monitoring”. Submit all records to the SO and adjacent property owners where directed.
Keep a copy of the survey report on site ready for inspection.
1.4.5 Instrumentation and Monitoring
Provide instrumentation to monitor the
ground
movement, vibration and condition of
adjacent properties. Refer to Section C2-50, Clause 3.1, and the drawings
for
the schedule of instrumentation required. If necessary or as
required by
the
authorities,
propose and provide additional instrumentation and monitoring for records.
Take cognisance of and co-ordinate with other contractors on site who may
be carrying out instrumentation and monitoring works to avoid duplication
of
installation and readings.
For general requirements of the instrumentation and monitoring works refer to Section
C2-50.
1.4.6 Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths
etc., where applicable, together with the mains and services from the time of taking
possession of the site through the duration of the works.
Adequately maintain roads and footpaths within and adjacent to the site and keep clear
of
mud and debris.
1.4.7 Verification of Site Information
1.4.7.1 Site Surveys
Verify
and be satisfied
that the information given in
the existing
site survey plans provided are accurate. If necessary, engage a registered Surveyor to carry out additional site survey before commencing any work.
1.4.7.2 Additional site investigations
Carry out additional ground investigation where additional information is needed for the
works or when directed by the SO. Carry out the works in compliance with Section C2-10 “Site Investigation”.
Carry out the boreholes progressively prior to
commencement of the works in areas
according to
the contractor’s construction programme. On completion of drilling, backfill
the
boreholes with a suitable bentonite / cement mix.
Submit the location and schedule for the boreholes to
SO’s acceptance prior to carrying out the works. On completion, prepare the site investigation report and submit to the SO
for acceptance.
1.4.7.3 Groundwater level
Verify the data on groundwater level from
available ground investigation reports.
1.4.7.4 Contamination
Verify information on contamination identified or believed to be present on site.
In the event that contamination is either positively identified or suspected, draw to the
attention of
all
personnel working
on site together
with the
need to take
any precautionary measures in handling contaminated materials,
groundwater
and obnoxious vapours from
the
ground.
1.4.8 Existing Services Affected by the Works
Refer to Preliminaries and Conditions of Contract for the requirements to deal with
existing services affected by the works.
1.4.9 Site Protection
Protect all equipment and working area using fencing or other methods as accepted.
1.4.10 Obstructions
If any obstructions such
as
existing
fences,
structures, footings, boulders, concrete blocks, pipes, drains, driveways or ramp are encountered
during excavation, submit
proposals for their removal for the SO's acceptance.
1.4.11 Supervision of the Works
Engage a competent and suitably experienced site engineer to the SO’s acceptance, to
supervise the field works.
1.4.12 Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to the General
Requirements section, clause 1.4.10 for guidance.
1.4.13 Safety
Provide safety precautions to comply with all current legislation and regulations, notably:
a. Building Control Regulations
b. Code of Practice for Traffic Control at Work Zone
c. Factories(Building Operations and Works of EngineeringConstruction)Regulations
d. Workplace Safety & Health Act
e. SS CP 79 Safety management
system for construction worksites
f. For works within LTA Railway Protection Zone,
ensure the works comply fully with Code of Practice for Railway Protection.
Additionally, comply also with the following:
a. BRE Digest
251 (1995) Assessment of damage in low rise building
b. BS 8008: Guide to safety precautions and procedures for
the
construction and descent of machine-bored shaft
for piling and other purposes
1.4.14 As-Build Pile Surveys
Employ a Licensed Surveyor who is to be responsible for surveying pile locations and eccentricities and submit the as–build survey to the SO in format as directed within 14
days
after the piles have been trimmed to the cut-off level.
1.5 Definitions|
a.
|
Pile Dimensions
|
Piles dimension specified in pile layout drawing(s) / piling
schedule are the minimum acceptable dimensions
|
|
b.
|
Rock
|
Material classified as grade I to III in table 10 “Scale of
weathering grades of
rock mass” in BS 5930: 1981.
|
2. PERFORMANCE REQUIREMENTS
2.1
Requirements for Design Verification
The required working load and sizes of the piles are indicated in the drawings, together
with an indication of the required
pile penetration depth.
Based on actual ground conditions encountered as revealed by boring logs or ground
investigations, carry out design check to confirm the required pile length as to achieve
the specified working
load
within
the
specified limits for load settlement behaviour
as indicated in Clause
2.2. Account for effects of negative
skin friction where applicable.
Verify the design
based on SS CP 4 unless otherwise agreed.
2.2 Performance Criteria for Bored Piles
Any of the piles,
when under static or dynamic
load test, is to satisfy
the performance criteria as set out below:
Axial Compression Tests (Ultimate and Working Load)
|
Pile Type
and Size
|
Specified
Working Load (Axial Compression)
|
Permitted Settlements (mm)
|
|||
|
(SWL)
(kN)
|
1.0*SWL
(2nd cycle)
|
1.5*SWL
(2nd cycle)
|
2.0*SWL
(2nd cycle)
|
Residual
Settlement
(End of 2nd
cycle)
|
|
|
900mm
diameter
Bored Pile
1200mm
diameter Bored Pile
|
4550
8500
|
7
7
|
15
15
|
25
25
|
7
7
|
In addition, the overall
pile capacity in ultimate
load tests is to have
factors of safety of at
least 2.5 against design ultimate compression
load, 2.0 against design ultimate lateral
load and 3.0 against design
ultimate tension load.
2.3 Permissible Damage
Criteria for Existing
Critical Structure or Services
Based on the results of the damage assessment as set out in Clause 1.4.2, propose
the allowable ground settlement and vibration limits due to the works taking into account the vulnerability and sensitivity
of
the
adjacent
properties
e.g.
VLCC
(48”
Crude Oil Pipelines).
State the values for alert and work suspension
levels in the submission in accordance
with the requirements of Building
Control Act [Section
7(2)] Annex (BE/CP/5).
Notwithstanding the above, ensure
that the ground movements and vibrations
generated by the works comply
with the following if more stringent:
a. Generally comply with the requirements of BS 5228 Part 1.
b. The vibration generated by the works in MRT structures not to exceed a peak
particle velocity of 15mm/s.
c. Unless otherwise directed, refer to Section C2-50, Clause 4.2.2
for general
restrictions
on ground movements
and vibration
limits
for adjacent structures where relevant.
d. Refer
to
piling drawings for vibration limits.
3. MATERIALS
3.1
Source of Materials
Do not change sources of supply until it has been demonstrated that the materials
from the new source can meet all the specified requirements.
Remove from site any material
that fails to comply with the specification.
3.2
Drilling Fluid
3.2.1 General Requirement
Where drilling fluid is used it
is to be such as to:
a. Provide continuous support of the excavation b. Be easily displaced
during concreting
c. Not pollute
the ground at any stage
d. Not coat the reinforcement such as to impair
the steel/concrete bond
Drilling fluid including Bentonite supplied to the site and prior to mixing is to be in accordance with API Specification 13A 5th Edition (1993) Drilling
Fluid.
3.3
Water
Water used for the construction
is to be clean and free from harmful matter in solution or
suspension.
If taken from a source other than the Public Utilities Board,
water is to be tested in
accordance with BS EN 1008.
3.4
Concrete
Refer to section C3-10, clause
3.0 for general
requirement of concrete.
3.5
Grout
Grout containing fine aggregate may be
used in place of concrete. Constituents are to be water,
ordinary Portland cement, fine aggregate where permitted and admixtures subject to agreement.
3.5.1 Minimum Cement Content
Minimum cement content
is to be 390kg/m3 for concrete to be placed under water or drilling fluid by tremie method.
3.5.2 Fine
Aggregate
Fine aggregate is to be in accordance with grading C or M of
SS 31 (1998) Table 6.
3.6
Reinforcement
Refer to section C3-20, clause
3.0 for general requirements of reinforcement.
3.7
Temporary Casings
Unless otherwise agreed with the SO, temporary casings of accepted quality or an
accepted alternative method is to be used to maintain the stability
of pile excavation.
Propose to SO’s acceptance, the depth, size and thickness of casing to be provided.
Temporary casings are to be free from significant
distortion. They are to be of uniform cross-section throughout each continuous length. During concreting they are to be free from
internal projections and encrusted concrete, which might prevent proper formation
of the piles.
3.8 Permanent Steel Casings
4. WORKMANSHIP
4.1 General Workmanship Requirements
Ensure the equipment set up and installation procedures are in conformance with SS CP
4: 2003.
4.1.1 Depth of
Penetration
Install each pile to
the designated penetration
as indicated
in the
drawings or as adjusted
as a
result of the design verification check.
4.1.2 Socketing of End Bearing Piles
For all piles indicated as end bearing in the drawings or schedules, form a socket of depth at least 1m or 1 times diameter, whichever is larger, into the material that meets
the founding conditions, unless indicated in the drawings or modified as a result of the verification check in clause 1.4.1,
as approved by the SO.
4.1.3 Pile Toe
Adopt a construction method, which ensures that the soil below the pile is not softened.
Ensure that no drilling fluid or slurry remains at
the base of the pile.
4.1.4 Continuity of Construction
4.1.4.1 Time for Excavation and Concreting
Each pile is to be excavated and concreted within twenty-four hours from the start of excavation below any temporary casing.
Where this time restraint cannot reasonably be met, set out an alternative in the method
statement together with an estimate of the likely effect on the performance and capacity of the pile.
4.1.4.2 Construction without temporary casing
A pile constructed
in
a stable cohesive soil without the use of temporary casing or other
form of support is to be bored and concreted without prolonged delay and in any case soon enough to ensure that the performance of the pile is not impaired.
4.2 Trial Bores
Conduct trial bores to confirm the ground conditions and the feasibility of the proposed
method of installation.
Agree with the SO on the location,
depth and size of the trial bores.
4.3 Boring
Excavation
4.3.1 General
Submit a detailed method statement clarifying the procedure for installing the bored piles including the method of overcoming any obstructions encountered and drilling through
hard
rock for SO’s acceptance. The method of excavation is to ensure no soil collapse in the bored holes. Do not
commence working pile excavation before method of excavation
is
accepted.
Carry out boring excavation generally using boring or reversed circulation drilling
equipment operating at the existing ground level.
Provide temporary steel
casing and drilling fluid if necessary to support the excavation.
Ensure the extreme dimensions (teeth
to
teeth) of the boring bucket or auger is not smaller than the specified pile diameter.
Do not dewater
within the excavated bored holes.
4.3.2 Boring Proximity
Do not bore so close to
piles that have been recently cast which contain workable or partially set concrete that a flow of concrete or instability could be induced or damage
sustained by any previously formed piles.
Boring is to be kept clear from a minimum distance of 5 times pile diameter from a newly cast
pile within 24 hours after casting.
4.3.3 Ground Conditions
Report to the SO immediately any apparent variance in the ground conditions from those
reported or might have been inferred from
reports.
4.3.4 Rock Socketing and Obstructions
When socketing through rock had been
called for or in the event of encountering obstructions below ground level during boring, use reverse circulation drilling method,
chiseling or propose other means for SO’s acceptance to bore through the obstruction or
rock.
Should the
reverse circulation
drilling
method fail to
clear the
obstruction or rock, propose and employ
other methods including predrilling with coring to assist in the clearing of the obstructions.
4.3.5 Temporary Casing
Unless otherwise agreed, provide a temporary casing of appropriate
size and length to
support the excavation. Use low vibration equipment to install and extract casing for
bores in built-up areas. Refer
to
design drawings for vibration limits.
4.3.6 Pumping from Pile Excavation
Do not pump from a pile excavation unless a casing has been placed into a stable stratum, which prevents the flow of water from other strata in significant quantities into
the
boring, or unless it can be shown that pumping will not have detrimental
effect on the
surrounding soil or property.
4.3.7 Determining Penetration Depth
Verify soil extracted as consistent with design assumptions in accordance with clause
1.4.1 above. Terminate
boring at the level indicated in the drawings, subject to
modifications as a result of verification check in clause 1.4.1. and to SO’s approval.
Keep soil samples drilled at strata change
and at 2m intervals for
records,
unless otherwise indicated in PSD. The
samples shall be stored in
a safe place which
is
sheltered from
sunlight and rain.
4.4 Use of Drilling Fluid
4.4.1 Proposal for
Use
Propose to the SO’s acceptance on
the
need to use drilling fluid. If acceptable, propose suitable type and method of drilling fluid to be used.
4.4.2 Storage
Store solid additives in
separate waterproof stores or containers, which
will prevent the
materials from
becoming contaminated.
4.4.3 Use
Use in accordance with the manufacturer’s instructions unless there is a demonstrable
reason to do otherwise.
4.4.4 Mixing
Mix drilling fluid thoroughly
with clean
fresh water to make a suspension, which will
maintain the stability of the pile excavation for the period necessary to place concrete and complete construction.
Where saline or chemically contaminated groundwater occurs, take special precautions to modify the drilling fluid suspension or prehydrate the drilling fluid in fresh water so as to render
it
suitable in all respects for the construction of piles.
4.4.5 Stability of Pile Excavation Using Drilling Fluid
Where the use of drilling fluid is accepted for maintaining the stability of
a boring, maintain the level of the
fluid in the excavation so that the fluid pressure
always exceeds
the
pressures exerted by the soils and groundwater. Use an adequate temporary casing
in
conjunction with the method to ensure
stability of the strata
near ground level until concrete has been placed.
Maintain the fluid level at a level not less than 2m above the level of the groundwater unless otherwise agreed.
In the event of a rapid loss of drilling fluid from the pile excavation, backfill the excavation
without delay
and inform the SO immediately. Obtain directions
from
the SO before excavation at that
location is resumed.
4.4.6 Spillage and Disposal
Take all reasonable steps to prevent the spillage
of
drilling fluid suspension on the site in areas outside the immediate vicinity of boring. Remove discarded drilling fluid from the
site without delay. Disposal of drilling
fluid is to comply with the regulations of the appropriate authority.
4.5 Cleanliness of Pile Bases
On completion of boring
and immediately prior to casting, remove all loose, disturbed or
remoulded soil or rock from the base of the pile while avoiding disturbance to the
ground
below
the
base. Maintain the stability of the
bore at all times, using appropriate levels of support fluid as required.
4.6 Reinforcement
4.6.1 General
Refer to section C3-20, clause 4.0.
4.6.2 Fixing
Nice post.
ReplyDeleteStructural piling repair