Download As 2159 Supp1-1996 Piling-Design and Installation-Guidelines PDF

TitleAs 2159 Supp1-1996 Piling-Design and Installation-Guidelines
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Table of Contents
                            AS 2159 SUPP1-1996  PILING - DESIGN AND INSTALLATION - GUIDELINES (SUPPLEMENT TO AS 2159-1995)
	PREFACE
	CONTENTS
	SECTION 1 SCOPE AND GENERAL
		1.1 SCOPE
		1.2 REFERENCED DOCUMENTS
	SECTION 2 SITE INVESTIGATIONS
		2.1 INTRODUCTORY NOTE
		2.2 PRELIMINARY INVESTIGATIONS
		2.3 INVESTIGATION TECHNIQUES
		2.4 BORE FREQUENCY/SPACING
		2.5 TESTS OF SOIL/ GROUND WATER AGGRESSIVENESS
		2.6 COMMENTS RELATING TO SPECIFIC PILE TYPES
			2.6.1 Driven piles
			2.6.2 Bored piles
			2.6.3 Continuous flight auger piles in soil
			2.6.4 Continuous flight auger piles on rock
	SECTION 3 REFERENCES FOR DESIGN CALCULATIONS
		3.1 GENERAL
		3.2 GENERAL REFERENCES
		3.3 AXIAL CAPACITY OF SINGLE PILES AND PILE GROUPS
		3.4 DYNAMIC ANALYSIS OF PILES (DRIVING AND DYNAMIC TESTING)
		3.5 SETTLEMENT OF SINGLE PILES, PILE GROUPS AND PILED RAFTS
		3.6 LATERAL RESPONSE OF PILES
		3.7 DYNAMIC RESPONSE OF SINGLE PILES AND PILE GROUPS
		3.8 MISCELLANEOUS TOPICS INCLUDING EFFECTS OF EXTERNAL SOIL MOVEMENT, TORSIONAL LOADING, BUCKLING AND STABILITY
	SECTION 4 DURABILITY
		4.1 CONCRETE PILES
			4.1.1 General
			4.1.2 Sulfate attack
			4. 1.3 Acid attack
			4.1.4 Chloride content
			4.1.5 Corrosion of reinforcement
			4.1.6 Industrial waste tips
			4.1.7 Unsuitable aggregates
			4.1.8 Frost attack
		4.2 STEEL PILES
			4.2.1 Introduction
			4.2.2 General
			4.2.3 Corrosion mechanisms
			4.2.4 Protective measures
		4.3 TIMBER PILES
			4.3.1 Timber preservation
		4.4 REFERENCES
	SECTION 5 TESTING
		5.1 INTRODUCTION
			5.1.1 Preamble
			5.1.2 Types of test program
			5.1.3 Selection of pile load
			5.1.4 Pile acceptability
		5.2 STATIC COMPRESSION LOAD TESTING OF PILES
			5.2.1 Introduction
			5.2.2 Delay between installation and testing
			5.2.3 Acceptance criteria
			5.2.4 Constant rate of penetration test (CRP)
		5.3 TENSION (UPLIFT) LOAD TESTING OF PILES
		5.4 LATERAL LOAD TESTING OF PILES
		5.5 DYNAMIC PILE TESTING
			5.5.1 Introduction
			5.5.2 The test method
		5.6 ALTERNATIVE TESTING METHODS
		5.7 INTEGRITY TESTING
			5.7.1 Introduction
			5.7.2 Low-strain integrity testing
                        
Document Text Contents
Page 1

AS 2159 Supp1—1996

AS 2159 Supplement 1—1996

Piling—Design and installation—
Guidelines

(Supplement to AS 2159—1995)

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Page 2

This Australian Standard was prepared by Committee CE/18, Piling. It was
approved on behalf of the Council of Standards Australia on 14 December 1995
and published on 5 March 1996.

The following interests are represented on Committee CE/18:

Association of Consulting Engineers, Australia

Australian Federation of Construction Contractors

Australian Geomechanics Society

Australian Uniform Building Regulations Coordinating Council

Austroads

Confederation of Australian Industry

CSIRO, Division of Applied Geomechanics

Department of Administrative Services — Australian Construction Services

Institution of Engineers, Australia

Monash University

Railways of Australia Committee

Timber Preservers Association of Australia

University of Sydney

Waterways Authority

Review of Australian Standards.To keep abreast of progress in industry, Australian Standards are
subject to periodic review and are kept up to date by the issue of amendments or new edit ions as
necessary. It is important therefore that Standards users ensure that they are in possession of the latest
editi on, and any amendments thereto.
Full details of all Australian Standards and related publications will be found in the Standards Australia
Catalogue of Publications; this information is supplemented each month by the magazine ‘The
Australian Standard’, which subscribing members receive, and which gives details of new publications,
new edit ions and amendments, and of withdrawn Standards.
Suggestions for improvements to Australian Standards, addressed to the head office of Standards
Australia, are welcomed. Notification of any inaccuracy or ambiguity found in an Australian Standard
should be made without delay in order that the matter may be investigated and appropriate action taken.

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Page 18

AS 2159 Supp1— 1996 16

S E C T I O N 4 D U R A B I L I T Y

4.1 CONCRETE PILES

4.1.1 General Good quality concrete has satisfactory durability for many purposes, but
for some applications consideration should be given to the effect of certain aggressive
agents on concrete below ground or in sea or fresh water. The extent to which precautions
are required, depends considerably on the particular site conditions, so that detailed
recommendations cannot be given. Much will depend on first hand knowledge of the
ground conditions surrounding the concrete; where there is any doubt, a ground
investigation should be undertaken together with a chemical analysis of the soil and
ground water. Particular care is needed with old industrial sites, landfill and mine sites.

4.1.2 Sulfate attack Sulfate salts may occur in solid form in the natural soil,
contaminated ground, fill or in dissolved form in ground waters or sea water. The rate of
attack for a particular type of cement depends on the concentration of the solution, the
ground water conditions and the permeability of the soil. The type of sulfate and the
chemistry of the ground can significantly affect the rate of attack. For example, the
chemistry of sea water leads to a lower risk of sulfate attack damage due to an absence of
expansion damage in the presence of both sulfates and chlorides in high concentrations.
The method of construction also has a significant effect on the rate of attack, as it
determines the age at which the surface is exposed to a sulfate environment.

To resist sulfate attack it is essential that concrete is dense and well compacted. Low
concrete permeability and choice of cement type is more important than high
characteristic strength. Soil permeability is an important factor and the ease with which
the contaminated ground water can move around and be replaced is all important. Where
piles are installed in an impermeable clay soil, acid or sulfate attack only penetrates the
concrete to such a small extent that the incorporation of a few centimetres of dense
‘sacrificial concrete’ will obviate the need for special cements.

Improved sulfate resistance can be achieved by using sulfate resisting cement.

4.1.3 Acid attack Well compacted, impermeable concrete, particularly if made with
limestone aggregates, is resistant to low concentrations of acid, but strong solutions will
attack concrete made with all types of cement. Pile jacketing or use of an alternative pile
material may be required in such cases. Creek and swamp water usually contains organic
acids from plant decay and free carbon dioxide which may slowly dissolve cement from
any concrete surface against which it flows. Porous concrete may be significantly affected
and therefore benefit from a protective membrane, but dense uncracked concrete will have
less need for protection.

Acidic soil can occur either naturally (e.g. humic and carbonic acids), or due to industrial,
mining or domestic contamination.

Resistance to water permeability and choice of cement type improve acid resistance. The
use of slag and flyash additives or the use of silica fume are highly beneficial in resisting
acidic attack.

The chemistry of the soil and ground water and the tendency for the Ph to change over
the service life of the pile should be carefully assessed. Organic activity and bacterial
activity can influence the dynamics of Ph over a period of time.

4.1.4 Chloride content Whenever there are chlorides in concrete above a threshold
concentration, there is a risk of corrosion to embedded steel.

It is recommended that the total chloride content of the concrete mix arising from the
aggregate together with that from any admixtures and any other external sources should
not exceed the limits given in AS 3600.

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Page 19

17 AS 2159 Supp1— 1996

4.1.5 Corrosion of reinforcement Steel in concrete is normally stable due to the
formation of an iron oxide film on the steel surface which occurs under alkaline
conditions. Corrosion initiation can occur either due to depletion of the concrete alkalinity
(e.g. acidic conditions or leaching of lime from the concrete), or by the presence of
chlorides (which break down the passive iron oxide film), or by other means (e.g. stray
current corrosion). The mechanisms leading to reinforcement corrosion damage are
commonly modelled qualitatively as a two-step process known as corrosion initiation and
corrosion propagation, described as follows:

(a) Corrosion initiation By assessing the severity of the service environment, the
design process should account for the provision of adequate concrete quality and
cover to reinforcement to ensure that corrosion initiation does not occur during the
service life of the piles.

For example, in the case of a pile located in a marine environment, chlorides can
diffuse through the cover zone of concrete, to initiate corrosion. The mechanisms of
chloride transport through the cover zone of concrete are different for each exposure
zone as follows:

(i) Submerged zone—waterborne chlorides are transported due to a hydrostatic
pressure gradient.

(ii) Splash zone—the wetting and drying effects of wave splash cause surface
transport of chlorides, via capillary suction of chlorides, followed by ionic
diffusion due to a concentration gradient.

(iii) Atmospheric zone—chlorides are deposited on the concrete surface either as
sea water droplets or as aerosol. Chloride penetration then occurs as a result
of ionic diffusion.

The threshold chloride content for predicting the risk of corrosion is commonly
expressed in terms of either total chloride content, free chloride content, or the free
chloride/hydroxide ion ratio. Due to laboratory requirements, total chloride content
is usually measured to assess corrosion risk a conservative threshold limit of 0.06%
(total weight of concrete) is given, although a range can be expected due to, e.g.
cement type.

(b) Corrosion propagation Once the reinforcement has been depassivated, corrosion
can be expected to propagate at a rate which depends on the availability of oxygen
to complete the cathodic reaction and also the resistivity of the electrolyte (cover
concrete). The resistivity of the cover concrete is chiefly a function of moisture
content. A corrosion cell is set up with an adjacent area of passive reinforcement
acting as a cathode where oxygen is reduced with the anodic dissolution of iron
taking place at a small central anode area.

Since the volume of the product of corrosion exceeds the volume of the parent reinforcing
steel, bursting pressures result in the subsequent cracking and spalling of the cover
concrete.

By utilizing environmental severity data, chloride resistant concrete can be designed and
specified to achieve a corrosion resistant service life. Where doubt exists, trial concrete
mixes can be manufactured and tested for chloride resistance. Chloride resistance can be
determined by imitating the service environment and, in the case of chloride ingress, a
penetration coefficient can be ascertained, which can be realistically specified to achieve a
corrosion-free life.

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Page 35

33 AS 2159 Supp1— 1996

(c) The tests should not be used as a final arbiter of good or defective piles, but as an
initial tool to detect possible major defects. Generally, consistency of signal
characteristics are often the first guide to determination of any significant
anomalies. A poor integrity test result warrants additional investigative work.

(d) Natural rules of physics determine the limitations of the test.

(e) Pile depth determination is not always possible.

(f) Small or gradual changes of soil conditions or pile section cannot be detected.

(g) In some ground conditions the test cannot distinguish between a reduced diameter of
pile (neck) and an increased diameter changing to the normal diameter.

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Page 36

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