www.cpaa.asn.auConcrete Pipe Associationof Australasia

This Australian Standard was prepared by Committee WS/6, Concrete Pipes. It wasapproved on behalf of the Council of Standards Australia on II September 1989 andpublished on 15 December 1989.

The following interests are represented on Committee WS/6:

Australian Construction Services

Board of Works, Melbourne

Confederation of Australian Industry

Engineering and Water Supply Department, S.A.

Hobart City Council

Municipal Association of Victoria

National Association of Australian State Road Authorities

Public Works Department, N.S.W.

Railways of Australia Committee

Rural Water Commission, Vic.

State Electricity Commission, Vic.

Water Board, Sydney

Water Resources Commission, Qld

Review of Australian Standards. To keep abreast ofprogress in industry, Australian Standards are subjectto periodic review and Ofe kept up-lo-dote by the issue of amendments or new editions as necessary. Itis important therefore that Standards users ensure thaI they are in possession of the latest edition, andany amendments thereto.Fu" details 0/all AUSTralian Standards and relaled publications will be found in Ihe Standards AustraliaCatalogue 0/Publications; this injormation is supplemented each month by the magazine 'The AuslralianStandard', which subsaibing members receive, and which gives derails of new publicotions, new editionsand amendments, and of withdrawn Standards.Suggestions for improvements to Australian Standards, addressed to the head office ofStandards Australia,are welcomed. Notification of any inaccuracy or ambiguity found in an Australian Standard should bemade without delay in order that the matter may be investigated and appropriate action taken.

This Standard was issued in draft form for comment as DR 86013.

AS 3725-1989

Australian Standard®,

Loads on buried concrete pipes

First published as AS A35-1937.AS A35-1937 revised and redesignated in parI as

AS CA33-1962.AS CA33-1962 revised and redesignated

AS 3725-1989.

PUBLISHED BY STANDARDS AUSTRALIA(STANDARDS ASSOCIATION OF AUSTRALIA)STANDARDS HOUSE, 80 ARTHUR ST, NORTH SYDNEY NSW

ISBN 0 7262 5945 4

AS 3725-1989 2

PREFACE

This Standard was prepared by the Standards Australia Committee on Concrete Pipes,to supersede AS CA33-1962, Code ofrecommended practice for concrete pipe layingdesign.The Standard provides rules for calculating the working loads on concrete pipes dueto fill and superimposed loads and relates these to the test loads applied to samplepipes in accordance with the methods of test set out in AS 1342, Precast concretedrainage pipes.The main purpose of the Standard is to enable an appropriate class of non-pressureconcrete pipe, manufactured in accordance with AS 1342, to be selected for use inparticular below-ground installations.The procedures in the Standard also apply to the calculation of external working loadson concrete pressure pipes. In this case, however, the loads due to internal pressuresneed to be considered in conjunction with the external loads. The method of assessingthe required strength of a pipe under this combination of loads, previously given inAppendix F of AS 1392 Precast concrete pressue pipe, is now included in this Standard.This Standard differs from AS CA33-1962 in the following principal respects:(a) Change of title. The Standard is concerned principally with the calculation of

working loads on buried pipes and the corresponding test loads. Importantinstallation criteria are also covered.

(b) Railway and road loads. Railway loading is now included. Rail and road bridgedesign rules, published by ANZRC (1974) and NAASRA (1976) respectively, haveallowed a simplified treatment of both these types of load to be presented withappropriate limits of application.

(c) Deletion ofappendices. Material previously in Appendix A and Appendix B hasbeen incorporated into the body of the Standard and Appendix C has beenincorporated in a Supplement.

Supplement No. I, which is the commentary on this Standard, contains supplementaryinformation and explanations of particular technical aspects of the Standard. Itincludes, as an appendix, examples of calculations in accordance with this Standard,particularly with reference to the selection of a pipe class from AS 1342.

© Copyright - STANDARDS AUSTRALIA

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Care should be taken to enSure that material used is from the current edition of the Standard and that it is updated whenever theStandard is amended or revised. The number and date of the Standard should therefore be clearly identified.The use ~r material in print form or in computer software programs to be used commercially, with or withoUl payment, or incommerCial contracts is subject to the payment of a royalty. This policy may be varied by Standards Australia at any time.

3

CONTENTS

I SCOPE .... . .2 APPLICATION . .3 REFERENCED DOCUMENTS .4 DEFINITIONS.... . . .5 NOTATION .6 VERTICAL LOADS ON PIPES .7 INTERNAL WATER LOADS .8 COMPACTION .... .... .... . .9 PIPE SUPPORT AND BEDDING FACTORS

10 TEST LOADS .... .... .... .... .... . ...

I

Page

444457

15151618

AS 3725-1989

AS 3725-1989 4

STANDARDS AUSTRALIA

Australian Standard

Loads on buried concrete pipes

3 REFERENCED DOCUMENTS. The followingdocuments are referred to in this Standard:

2 APPLICATION. This Standard applies toconcrete pipes complying with AS 1342 or AS 1392,where they are laid or intended to be laid in one orother of the specified installation conditions. It mayalso be applied to other types of buried pipe of similarrigidity and installed under equivalent conditions, ifthe prescribed bedding factors are suitably modified.

This Standard does not apply to flexible buried pipes.

1 SCOPE. This Standard sets out methods andprovides data for-

(a) calculating the vertical working loads on buriedconcrete pipes due to-

(i) the materials covering the pipes; and

(ii) superimposed loads; and

(b) relating the minimum test cracking load to beapplied to sample concrete pipes, in accordancewith AS 1342 and AS 1392. to the calculatedvertical working loads on concrete pipes installedunder particular conditions, including that ofcombined vertical load plus internal pressure.

In addition, the Standard classifies types of pipeinstallation and types of bedding and sets minimumrequirements for the soil materials around the pipesand compaction of these materials.

AS1289

1289.C6.1

1289.EI.I

1289.E3.2

1289.E3.5

1289.E4.11289.E5.l

1289.E6.1

1289.F2.1

1342

1392

Methods of testing soils for engineeringpurposesDetermination of the particle sizedistribution of a soil-Standard method ofanalysis by sievingDetermination of the dry density/moisturecontent relation of a soil using standardcompaction-Standard methodDetermination of field dry density of asoil-Sand replacement method using asand pouring apparatusDetermination of field dry density of asoil-Water replacement methodDry density ratio-Normal methodDetermination of maximum and minimumdry density of a cohesionless materialCompaction control test-Density indexmethod for a cohesion!ess materialDetermination of the shear strength of asoil-Field test using a vanePrecast concrete drainage pipes

Precast concrete pressure pipes

Bridge design specification. National Association ofAustralian State Road Authorities (NAASRA) (1976)Railway bridge design manual. Australian and NewZealand Railway Conferences (ANZRC) (1974)

4 DEFINITIONS. For the purpose of thisStandard, the definitions below apply.Bed zone-the area between the foundation and thelevel of the bottom of the pipe, whose depth isdetermined in accordance with Clause 9.2 (seeFigure I).Bedding-the specified type and extent of materialssupporting the lower portion of the pipe usually takento be the materials occupying the bed zone and thehaunch zone.Beddingfactor (F)-the ratio of the calculated workingload on a pipe to the-appropriate test load specifiedin AS 1342 and AS 1392.Fill-one or more of the following:(a) Backfill or embankment fill-material placed over

the overlay zone for the purpose of refilling atrench or creating an embankment (see Figure I).

(b) Ordinary flll-material obtained from excavationof the pipe trench or elsewhere and containing notmore than 20 percent by mass of stones with a sizebetween 75 mm and 150 mm and none larger than150 mm.

(c) Select fill-material obtained from excavation ofthe pipe trench or elsewhere with a particle sizenot greater than 75 mm, and which conforms withthe following soil classes as defined in Appendix Dof AS 1726.SC clayey sands with fines of low plasticitySP poorly graded sandsSW well graded sandsOC clayey gravels with fines of low plasticityOW well graded sand and gravel mixtures with

little or no plastic finesOP poorly graded sand and gravel mixtures with

little or no plastic finesFoundation*-naturally occurring or replaced materialbeneath the pipe bed.Haunch zones-the areas bounded by the trench wallsand the outside of the pipe, the top of the bed zoneand a level surface whose height above the bottom ofthe pipe is determined in accordance with Clause 9.3(see Figure I).Installation condition*-the configuration of the cross­section of a pipe installation being one of thefollowing:(a) Trench condition-the installation condition

illustrated by Figure 2.

1726 Site investigations

3600 Concrete structures • See Commentary

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TRENCH

Natural groundsurface

Trench wall

Overlay zone

5

~ EMBANKMENTI Finished surface,

x

FoundationI

AS 3725-1989

FIGURE 1 FILL AND PIPE SUPPORT TERMS

(b) Induced trench condition-the installationcondition illustrated by Figure 4(b).

(c) Embankment condition (positive projection)-theinstallation condition illustrated by Figure 3.

(d) Embankment condition (negative projection)-theinstallation condition illustrated by Figure 4(a).

(e) Jacked or bored condition-the installationcondition illustrated by Figure 6.

Overlay zone-the area extending around the outsideof the pipe to the tops of the last placed side zone,haunch zone, or bed zone as appropriate, and whichhas a breadth of not less than 300 mm at any pointmeasured radially from the outside of the pipe (seeFigure I).Pipe-a length of pipe cast as a single unit.Settlement ratio(r,)*-a dimensionless numberindicative of the relative settlements of the pipe andadjacent fill in an embankment condition.

Side zones-the areas bounded by the trench walls andthe outside of the pipe, the top of the haunch zonesand a level surface whose height above the bottom ofthe pipe is not less than O.7D (see Figure I).Superimposed load-the vertical components of a loadapplied to the surface of the fill above a pipe.Test load-the load, calculated in accordance withClause 10, which sample pipes are required to sustainin accordance with AS 1342.Working load~venical component of the maximumexternal dead load or live load acting at the level ofthe top of an installed pipe, calculated in accordancewith Clause 6.

5 NOTATION. The quantity symbols used in thisStandard are listed and defined below.

• See Commentary.

QuantityDefinition Unit of

Text referencesymhol measurement

A area of the base of a load prism m' 6.5.1a length defined in Figure 10 m 6.5.1.1B = width of the trench measured at

the top of the pipe(s) mb length defined in Figure 10 m 6.5.1.1

C', coefficient obtained fromFigure 8* 6.3.3

C'" = coefficient obtained fromFigure 9* 6.3.4

C, = coefficient obtained fromFigure 7 6.3.2, 6.3.6

c = a soil parameter kPa 6.3.7, Table 2D = external diameter of a pipe mF = bedding factor 9G distance defined in Figure 9 m 6.5.1.1

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AS 3725-1989 6

QuantityDefinition Unit of

Text referencesymbol measurement

H ; vertical distance from the top ofa pipe to the finished ground orroad surface, or to the top of therails m

H, equivalent height of fill m 6.4h vertical distance from the top of

the pipe down to the level of theadjacent undisturbed foundationor trench bottom, whichever isthe lesser m Figures 3, 5

h' depth of loose fiJI or straw-bales m Figure 410 density index percent 8

L, length of the base of the load 6.5.2.2, 6.5.2.4prisms measured parallel to thepipe axis m

L, length of the base of the loadprisms measured perpendicular tothe pipe axis ll) 6.5.2.2

L, effective length of pipesupporting the load m 6.5.2.4

P wheel load; or a railway axleload kN 6.5.2.2, Figure 12

P, hydrostatic test pressuredetermined in accordance withAS 1392 kPa 10.4

Pw ; internal working pressure kPa 10.4p positive projection ratio, hiD Figure 8p' negative projection ratio, h' /D Figure 9q ; average intensity of the working

live load at the level of the topkN/m'of the pipe 6.5

Ro dry density ratio percent 8r, settlement ratio 6.3.5S L" or D, whichever is the lesser m 6.5.2.4T, test cracking load for pipes not

subject to internal pressure kN/m 10.2T,p ; test cracking load for pipes

subject to internal pressure kN/m 10.4

T. test ultimate load kN/m 10.3

u superimposed uniformly-distributed dead load kN/m' 6.4

W, calculated working load on apipe due to external dead loads kN/m 6.3

Wq ; calculated working load on apipe due to external live loads kN/m 6.5

w assessed unit weight of fillmaterial* kN/m' 6.3, 6.4

X ; depth of bed zone m 9.2.1.1, 9.2.1.2y ; depth of haunch zones m 9.2.1.1, 9.2.1.2Z height -of top of side zone above

bottom of pipe m Figure I

ex live load impact factor 6.5.2.2

• See Commentary.

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6 VERTICAL LOADS ON PIPES.

6.1 Types of loading. In the design or selection ofa concrete pipe an assessment shall be made of thefollowing types of vertical loads:(a) Working load due to the fill material.(b) Working load due to superimposed dead loads.(c) Working load due to superimposed live loads.

6.2 Data required. To assess the working loads onpipes in accordance with this Standard, the followingknown or assumed data is required:(a) Height of the fill material above the top of the

pipes.(b) Assessed unit weight of the fill material.(c) Magnitude and nature of any superimposed loads.(d) Type of support and foundation materials.(e) Pipe installation conditions (see Clause 6.3).

7 AS 3725-1989

(f) Projection ratio where the pipes are installed withpositive or negative projection in embankmentconditions.

(g) Width of trench if the pipes are installed undertrench or induced trench conditions.

(h) External diameter of the pipes.

6.3 Working dead loads due to fill or in-situmaterials.

6.3.1 General. Working loads, due to the dead loadof fill or in-situ materials. shall be calculated in accor­dance with Clauses 6.3.2 to 6.3.7, as appropriate.

6.3.2 Trench condition. Where pipes are laid in atrench (see Figure 2), the working load due to fill (Wg),

is the lesser of the values calculated from Equation Ibelow and Equation 2 in Clause 6.3.3.

Wg ~ C,wB2 (I)

where C, is obtained from Figure 7.I

-'-

_.-

TH

/

' ...

B'

Natural groundsurface

Fill

_._.~

. -.-.-'. ""

o

FIGURE 2 TRENCH CONDITION

FIGURE 3 EMBANKMENT CONDITION (POSITIVE PROJECTION)

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AS 3725-1989 8

• See Commentary.

uH, = - (5)w

TABLE 2SOIL PARAMETER (c)

6.4 Working loads due to superimposed deadloads. A superimposed uniformly-distributed deadload (u) may be treated as an equivalent height of fill(H,) calculated from Equation 5:

5

o5

15

21550

Parameter (C)Type of soil

ClaySoftFirmStiff

SandVery looseLooseDense

LoamSaturated

6.3.7 Jacked or bored pipes. Where pipes areinstalled by jacking or boring (see Figure 6), theworking load due to the material over the pipe (W,)is calculated from Equation 4-

W, = c,wE'- - 2cC,B (4)

where C, is obtained from Figure 7; andc = the soil parameter given in Table 2.

The working load due to the superimposed dead loadmay then be calculated in accordance withClauses 6.3.2 to 6.3.6 inclusive, by substituting(H + H,) for H in the relevant equations or figures,as appropriate.Superimposed concentrated dead loads should beavoided.'

Projection type Foundation Settlementtype ratio (r5 )

Positive (Figure 3) Any + 1.0

Negative and Earth -0.5induced trench Rock - 1.0(Figure 4)

TABLE 1SETTLEMENT RATIOS

6.3.3 Embankment condition (positive projection).Where pipes are laid in an embankment with their topsprojecting above the adjacent natural or equivalentsurface' (see Figure 3), the working load due to fill(W,) is calculated from Equation 2.

W, = C',wDH (2)

where C', is obtained from Figure 8 using a value ofr, obtained from Clause 6.3.5.

6.3.4 Embankment condition (negative projection orinduced trench) condition. Where pipes are laid in anembankment with their tops either above or below theadjacent natural or equivalent surface*, and coveredwith a layer of compressible material (see Figure 4),working load due to fill (W,) is calculated fromEquation 3

W, = C'"wBH (3)where C'" is obtained from Figure 9 using a value ofr, obtained from Clause 6.3.5.

6.3.5 Settlement ratio. The settlement ratio (r,) tobe used in Figure 8 and Figure 9 shall be as given inTable I for the corresponding type of projection andfoundation in the installation.

6.3.6 Multiple pipes. Where two or more pipes arelaid side-by-side in a single trench or embankment (seeFigure 5), the working load per pipe due to fill (W,)shall be calculated from Equation 2 in Clause 6.3.3.

o

Top of embankment

Naturalgroundsurface

Top of embankment

H

" . .' B .. ' .'

hr----~·~~'.'~-~-~ Comp~essible.l_-=~===::;.~.~.:::: ... . ma t er ral

....~

'-

rNaturalgroundsurface

Compressiblematerial

........:-.

-'-

-'-

H __T

la) Negative projectionNOTE: B Is usually equal to,

but not less than D.

Ibl Induced trench

FIGURE 4 EMBANKMENT CONDITION (NEGATIVE PROJECTION ORINDUCED TRENCH)

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9 AS 3725-1989

Natural

Finished surfacegroundsurface

T-"- -"- -"--"-

H -"- -"- -- --

-"- -"- Fill-"- --

h

FIGURE 5 MULTIPLE PIPES

Naturallound surface

D

FIGURE 6 JACKED OR BORED PIPES

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AS 3725-1989 10

VALUES OF HB

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 185 5

Curve A4 4

Curve B

Curve

3 3

2

LLo(J)W:J...J<:>

1.3

0.2

0.6

1.5 \.l

1.4 f-

lai52LLlLWoo

1.2

0.4

1 .1

0.7

1.0

0.9

0.5

0.8

0.3

---• V / /'

/ ~/// ./~~

",.",

LEGEND, / ~~/'Curve A = wet clayCurve B = clayey sand / ~:/Curve C = sand and gravel

"~

.","--- Curve A/ A

// ~~ ""~

~

"'""--- Curve B

"'" "-- Curve C

~1/

/Y

0.3

0.2

0.6

0.7

0.5

0.4

0.1 0.10.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8

VALUES OF ~

LLo(J)W:J...J<:>

f- 1zw52LLLLWoo

FIGURE 7 VALUES OF COEFFICIENT (G,l FOR TRENCH CONDITION

CDPYRIGHT

1.6

-~()

LL 1.4

I 0UJ

Jw:::>--'..:>

1.2

1.0

II

Irsp 1.0

fI

rs p=0.8

Ifrsp = (l.5

Ir7 rsp 0.3

/r! rsp = 0.1

77 rsp = 0.0

AS 3725-1989

o 2 4

VALUES OF 1io

6 8 10

IJ

NOTES;I. The curves are drawn tor granular soils and are slightly conservative for other materials.2. For values of " see Clause 6.3.5, Table 1.3. p = hid

FIGURE 8 VALUES OF COEFFICIENT (C'.) FOR EMBANKMENT CONDITION(POSITIVE PROJECTION) (Equation (2))

COPYRIGHT

0.2

> 'J>

W ~ ~ ~ I ~)~

{s

1 0. 0

"' ~{

sI0

.5

"'" '"{

s1.

0

-r--...

_c o ~

0.6

(J)

~0.

4-' « >

0.2

0.8

1.0

I"\..

I

"'{

s0

.0

II

"-{

S'

0.5

I

........

.. ..........

.{

s1.

0

....... r--

+-.

1.0

0.8

,c o ~0

.6

(J)

~0.

4-' « >

oo

24

68

1012

VA

LUE

SO

F~

lal

p'

=0

.5

1416

oo

24

68

1012

VA

LUE

SO

F~

lbl

p'=

1.0

1416

() 0

1.0

." -< ::0 Gi0

.8:I

:-;

,c 0 ~

0.6

(J)

~0.

4-' « >

0.2

~

"{

s0

.0

--{

s0

.5

..........

::'"~

1.0

0.8

,c o ~

0.6

(J)

~0.

4-' « >

0.2

~1

'- ........

{s

0.0

..........

. ~{

sI

0.5

-I--

{s

1.0

~

;:;

oo

24

68

1012

VA

LUE

SO

F~

Ie)

p'

=1.

5

1416

oo

24

~AL

U:S

OF10

~12

(dl

p'

=2

.0

1416

FIG

UR

E9

VA

LUE

SO

FC

OE

FF

ICIE

NT

(C',)

FO

RE

MB

AN

KM

EN

TC

ON

DIT

ION

(NE

GA

TIV

EP

RO

JEC

TIO

NO

RIN

DU

CE

DT

RE

NC

H)

(Equ

atio

n(3

))

c

6.5 Working loads due to superimposed live loads.

6.5.1 General. The working load due tosuperimposed live-loads shall be calculated in accor­dance with Clauses 6.5.2 to 6.5.5, as appropriate.Impact effects shall be taken into account for all live­loads by multiplying the superimposed load by anappropriate impact factor (ex-).

6.5.2 Road vehicle loads.

6.5.2.1 Calculation. Unless otherwise specified bythe relevant Regulatory Authority, working loads dueto road vehicles shall be not less than those calculatedin accordance with Clauses 6.5.2.2. to 6.5.2.4, asappropriate.

6.5.2.2 Distribution of wheel loads. Where theheight of fill (H) above a pipe is greater than 0.6 m,single wheel loads may be assumed to be distributeduniformly through a prism of fill or natural groundof height (H) the base of which is horizontal and isconcentric with and has dimensions 1.45H greater thanthe surface contact area of the wheel.

Where multiple wheels, or vehicles in adjacent lanesare being considered and the bases of the load-prismsso formed overlap (see Figure 10), it may be furtherassumed that the sum of the individual wheel loadsis uniformly distributed over the area within the netperiphery of the prism bases (for Figure 10, this areawould be (a + 1.45H)(G + b + 1.45H).

On the basis of these assumptions, the averageintensity of live load (q) at the top of a pipe due tomultiple wheel loads, including impact effects, iscalculated from Equation 6:

13 AS 3725-1989

q = ar.p ........•.•..........•......... (6)A

wherer.p the sum of the individual wheel loads, in

kilonewtons

A = the area within the net periphery of theload-prism bases, in square metresL, x L,

Ol the appropriate impact factor.-

Where the height of fill above a pipe is less than 0.6 m,the above assumptions may not apply.-

6.5.2.3 NAASRA vehicle loads. Unless otherwisespecified by the relevant Regulatory Authority, vehicleloads shall be taken as the Standard AI4 and T44highway-vehicle loads specified in NAASRA BridgeDesign Specification-1976.The average live load intensity (q) )Iue to these vehiclesand their impact effects may be calculated in accor­dance with Clause 6.5.2.2 or obtained from Figure II.

NOTES,I. Figure 11 was· prepared on the basis of Clause 6.5.2.2 using

the data for a single NAASRA AI4 and T44 vehicle.

2. NAASRA recommends that for depths of cover less than0.6 ro, the wheel loads should be considered to act dire<:tlyon the pipe. However, the length of pipe supponing the loadmay be taken as L t (see Clause 6.5.2.4).

3. For single pipes, the effect of NAASRA wheel loads may beneglected when the depth of cover (If) is greater than 2.4 mand exceeds the pipe diameter (D).

... See Commentary.

p

,

p

~~~~~~~L1~=~I:G:+:lb + 1.45HI If load prisms overlapor Ib + 1.45H} If no overlap

FIGURE 10 DISTRIBUTION OF WHEEL LOADS

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AS 3725-1989 14

2.5 3.0 3.5 4.0 4.5 5.0

FROM TOP OF PIPE (H), m

~

-

,f--II

I-II

:;-II

:f- -- Single laneI -- Dual laneI

III

I

~II

I

~I

f-iI

~III

~~ ~~I

Li"]it 0\ ap~licat,ion~I , " " , , I ~

5

o0.05 1.0 1.5 2.0

HEIGHT OF COVER

u.. 15o

o 45«~ 40

~ 35...Ja.D 30«o 25...J

0- 50

~ 20

>- 10f-(j)ZWf-Z

N 60E"-~ 55

FIGURE 11 LOAD INTENSITY (q) DUE TO SINGLE NAASRAA14 AND T44 VEHICLES

Natural ground surface

H

0.750

0.750

H

N tural ground surface

p

! r ah~

I

vOIIA~7··· .. : .. : ..,'l, .... \>~HAW '.IIAV//

P /1 L, [,L ___ - ---- ---- ..!.~ ~

L.= L,+ (to x 0.7501

o1

FIGURE 12 EFFECTIVE PIPE LENGTH (L,) JCOPYRiGHT

15 AS 3725-1989

6.5.2.4 Working loads due to other roadvehicles. Where the vertical depth from a roadsurface to the top of a pipe is equal to or greater than0.6 m, the working live load due to road vehicles iscalculated from Equation 7:

Wq _ qL,S (7)L,

where

q is determined from Clause 6.5.2.2 orClause 6.5.2.3, as appropriate

S is defined in Clause 5L, and L, are derived as shown in Figure 12.

6.5.3 Railway loading. Unless otherwise specifiedby the relevant Regulatory Authority, railway loadsfor each track shall be the standard 'Metric CooperM250' axle loads specified in ANZRC Railway BridgeDesign Manual-1974.

For depths of cover (H) of 1.0 m or greater, theaverage live load intensity (q) on buried pipes due tothe standard M250 railway loads and impact effectsmay be obtained from Figure 13 for a single 1435 mmgauge track (see Note).

For depths of cover of 1.0 m or greater, the workinglive load (Wq ) due to railway loads shall be calculatedfrom Equation 7 in Clause 6.5.2.4, using a value ofq obtained from Figure 13 and using S = D.~

Depths of cover (H) less than 1.0 m shall not be usedunless specifically approved by the relevant RailwayAuthority.

6.5.4 Aircraft loads. Required loads and loaddistributions for the assessment of working loads dueto aircraft shall be obtained from the relevantRegulatory Authority.

6.5.5 Construction and other equipmentloads. Where heavy equipment is required to travelover pipes during construCtion of the pipeline, thepipes shall be checked for these loading conditions.

Wheel loads, together with impact effects due to theequipment and surface conditions, shall be assessed,and Clauses 6.5.2.2 and 6.5.2.4 may be used as a guidefor determining the appropriate working loads.

7 INTERNAL WATER LOADS. The verticalworking load on pipes due to the mass of water carriedby the pipe may be disregarded for pipes less than1800 mm diameter but should be considered for largerdiameter pipes. Pipes subject to internal liquidpressures in addition to external loads, shall be treatedin accordance with Clause 10.4.,,

8 COMPACTION. Special attention shall begiven, during installation of pipes, to compaction ofthe material under and around pipes to ensure that thedegree of support and soil/pipe interaction assumedfor the various bedding factors given in Clause 9 isachieved. *Where a percentage compaction is specified inClause 9, it shall be measured by one of the followingparameters as applicable:

'" See Commentary.

10PIPE

23456789OF COVER FROM TOP OF THE

TO RAIL LEVEL IH I, m

III

III

III

II

i\I,I

I II II I

I '\ II II I

I I II I NI I

I I '" '-lI I I, I I

I I i I N--- II I I I I ""4..

L, , I , ,

~I ILimit of application, II I I I ..,

oo 1

HEIGHT

30LLo>- 20>-Ui 10zw>­z

w 40>::J

>- 90()

~ 80::>(/J 70:::J--'"- 60o<: 50o--'

N 120E"-z 110""--' 1000"

NOTE: Figure 13 was compiled using live load values from the American Railway Engineering Association's Manual for Railway Engineering,suitably modified for the standard M250 axle loads.

FIGURE 13 LOAD INTENSITY (q) DUE TO METRIC COOPER M250 RAILWAYLOADS

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AS 3725-1989 16

(a) Cohesive soils. The dry density ratio (Ro)determined in accordance with AS 1289.E4.I,based on the field dry density in accordance withAS 1289.E3.2 and the maximum dry density inaccordance with AS 1289.EI.1.

(b) Cohesionless soils. The density index (Ia)determined in accnrdance with AS 1289.E6.I,based on the maximum and minimum dry densitiesin accordance with AS 1289.E5.1 and the field drydensity in accordance with AS 1289.E3.2 orAS 1289.E3.5.

9 PIPE SUPPORT AND BEDDING FACTORS.

Where the pipes have protruding sockets, suitablechases shall be provided in the supporting materials,including the foundation where necessary, to ensurethat the pipes do not bear on their sockets.

9.1.2 Bedding/actors. The bedding factor (F) to beapplied to working loads, for the purpose ofClause 10, shall be-

(a) determined in accordance with Clause 9.3 forloads due to fill and superimposed dead loads; and

(b) taken as 1.5 for all live loads irrespective of thetype of pipe support provided.

9.1 General.

9.1.1 Pipe supports. Each pipe shall be evenly anduniformly supported along the length of its barrel bysuitable fill material in the various support zones.

The material used in the support zones shall be freefrom organic materials or other materials harmful tothe pipes and shall otherwise comply with the relevantrequirement of Clause 9.2. It shall be compacted byappropriate methods to ensure that at least the degreeof compaction specified in Clause 9.3 is achieved inthe field.

9.2 Support types.

9.2.1 Type U support. For soil foundations whichcomply with the definitions of select fill given inClause 4, the pipe may be supported directly on thefoundation.

For rock foundations or soil foundations not of selectfill, the support shall consist of a bed zone of selectfill of depth not less than 75 mm.

In both cases ordinary fill nr finer material shall beused in the overlay zone (see Figure 14).

Naturalgroundsurface

. '_ .....0.3 m min..~

.. ' .. ::-:- ..

"."_'-,' .-

0,3 m min.

Ordinary fill ---=:;ilDwrm

Finished surface

Na tural groundsurface

01

'-------Compacted select fill---~

~0,2Dand

~0.3 m

, ,,._._ ", Sack fill',·· ....'t·, -.,"

)(

D

0.3 mmin.

Htttttti~~11

Trench (b) Embankment

FIGURE 14 TYPE 'u' SUPPORT

rFinished surface

'-'-

~O.2Dand

~O.3 m

-,,-,',,':2",:,-0 . •....•. t:< ...• ,"'_. ' :,:" Embankment fill

-.-----':'-'--,'.'~•. ,-'''!'-'.=--''--+'';",' j..~.,~:

,,•_",_. ',' I o_3_.m. min,

--'--:-:-""':-"-:'ir1ffirtfftjj;!!:::;:~1 Nat ura II ground+ surface

0.3 m min.

Natural groundsurface

Finished surface

Co mp ac te d __-~i::::='ttmllordinary fill ~,',-:':":'-'::"H'+H1H111

Compacted select fill ~~888881.-.L to Table 3 grading~~~~

','-'

~0,2Dand

~O.3 m

Backfill-:-:7,: '

03mnm

min'-L---ttttttt1!ttJ;ll;~\ill1

(al Trench (bl EmbankmentFIGURE 15 TYPE H1 AND H2 SUPPORT

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17 AS 3725-1989

* See Commentary.

(b) it is cement stabilized*.Pea gravel shall not be used in either the bed zone orthe haunch zone.

9.2.2.3 Type H3 support. For support lype H3, themalerial of the bed and haunch zones shall bereinforced or plain concrete complying with AS 3600with a characteristic compressive strength of not lessthan 20 MPa and shall be placeq, and compacted tothe appropriale widths and depths given in Figure 16.Vertical transverse construction joints, where requiredin the support, shall coincide with pipe joints. Betweenthese joints the cross-section should preferably be castin one operation. If this cannot be achieved, shear keysshall be provided in any horizontal construction j?intto ensure monolithic action of the cradle cross-sectIOn.

9.2.2 Type H support.9.2.2.1 General. The support shall consist of a bedzone and haunch zone of-(a) for types HI and H2-

(i) compacted select fill cornplying with thegrading limits given in Clause 9.2.2.2; or

(iI) compacted cement-stabilized select fill; or(b) for type H3, concrete complying with

Clause 9.2.2.3.For type HI, H2 and H3 supports, the overlay zoneshall consist of compacted ordinary fill or compactedfill of finer grading (see Figures 15 and 16).

9.2.2.2 Types Hi and H2. For supporttypes HI andH2 select fill in both the bed and the haunch zones andwhich is not cement stabilized, shall have a particle sizedistribution determined in accordance with AS 1289.C6.1,preferably falling within the limits given in Table 3 withthe fraction passing the 0.075 mm sieve being matenalof low plasticity, as defined in Appendix 0 of AS 1726.The fill shall be placed and compacted to the approp­riate depths and densities given in Clause 9.3.Select fill with the fraction passing the 0.6 mm sievenot conforming to the above limits may be used in thebed and haunch zones provided that-(a) it can be demonstrated that the required degree

of compaction can be attained in the field and thereduction to the bedding factor given inClause 9.3.2 is applied; or

Sieve sizemm

19.02.360.600.300.150.075

Weight passing%

lao100 to 5090 to 2060 to 1025 to 010 to 0

r rFi~ed surface

~0.2 0 and ~O.3 m Natural ground surface""",,'Y/AW' ..

· •. Bacidillw",'Ylk/11..... ,'

'-

mn-

0.3 m min! l.--- Compac ted ordinary fill:1 ,

1 ~-t- "

X

Y~ .A·.·~ , A .•'l. .... ] Grade N20 concreter A'.""" '.~'.'l." to AS 3600fl"w,

FIGURE 16 TYPE H3 SUPPORT

......

-.-", ,"

-'-

'<~'.

~ 0.2 D an d ~'~O~.3~m~t=::::("'~J..1F:!in~i~s!!h~egd2.su~r:.!f~aQc~e'~."_:', :~ ," ... ..:....:....:..... :-.surface

Naturalgroundsurface

, ,

~0.2Dand

~0.3 m•

(al Trench (bl Embankment

FIGURE 17 TYPE HS SUPPORT

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AS 3725-1989 18

Temporary pipe supports may be left within theconcrete provided that they have no adverse effects oneither the pipes or the support.Type H3 support shall not be used for pipes containingelliptical reinforcement.

9.2.3 7jlpe HS support.

9.2.3.1 General. The support shall consist of eithera Type H I or a Type H2 support complying withClause 9.2.2, plus side zones of material complyingwith Clause 9.2.3.2.The overlay zone shall consist of compacted ordinaryfill or compacted fill of finer grading.The side zones shall not be considered to be effectivein supporting the pipes unless the trench walls havea density and stiffness not less than those of theadjacent compacted fill, to a height of O.7D above thebottom of the pipe and for a lateral distance outsideeach trench wall of not less than 1.5D for supportTypes HSI or HS2 and 2.5D for Type HS3.

NOTE: Materials which may not meet [he requirements of (helasl paragraph include soft clays, soil~ containing organic materialsand swelling soils.

9.2.3.2 Side zones. Materials in the side zones shallbe select fill having a particle size distribution,determined in accordance with AS 1289.C6.1, fallingwithin the limits given in Table 4 and shall be placedand compacted for the depth of the zone to theappropriate densities given in Clause 9.3.

TABLE 4GRADING LIMITS FOR SELECT FILL IN SIDE

ZONES

Sieve sizemm

75.09.52.36

0.600.075

Weight passing'10

100100 [0 50tOO to 30

50 to 1525 to 0

9.3 Bedding faclors for dead loads.

9.3.1 General. For Types U, Hand HS supports,the bedding factor (F) to be applied to working deadloads for the purpose of Clause 10.2, shall be notgreater than the values given in Table 5, correspondingto the type of support and minimum degree ofcompaction of the various zones given in the Table,and as otherwise provided in Clause 9.3.2. For jackedor bored pipes, the bedding factor shall be as givenin Clause 9.3.3.

9.3.2 Reduction of bedding factors. The beddingfactors given in Table 5 for Type Hand HS supports,shall be reduced by 15"70, if the select fill in the bedor haunch zones has a grading curve with the fractionpassing the 0.6 mm sieve falling outside the limits givenin Table 3, and is not cement stabilized.

9.3.3 Jacked or bored pipes. For jacked or boredpipes, the bedding factor (F) applied in accordancewith Clause 10.2 to working loads due to fill andsuperimposed dead loads, shall be in the range 2 to 3*.

10 TEST LOADS.

10.1 General. The external load-carrying capacityof an installed pipe is determined on the basis of theperformance of sample pipes under a load test. Thetest load on the sample pipes shall be calculated inaccordance with Clauses 10.2 to lOA, as appropriate.The pipes shall be sampled and tested in accordancewith the methods described in AS 1342 or AS 1392,as appropriate. It is assumed that the load-carryingcapacity determined in this manner is equivalent to thepipe's load-carrying capacity under external workingloads and internal working pressures.

10.2 Test loads for reinforced pipes not subject 10internal pressure. For reinforced pipes not subjectto internal pressure, or for which the required testpressure is not greater than 100 kPa-

'" See Commentary

TABLE 5BEDDING FACTORS FOR WORKING DEAD LOADS

(U, Hand HS Supports)

Minimum deplh, mm Minimum zone compaction, 'I,. MaximumSupporl

Bed and haunchbedding

type Bed lone Haunch zone lones Side zones faclor

X T yT 10 + 10 + Ro+ (f)

U 75 - - - - 1.0

100 ifD " I 500; O.ID 50 - - 1.5

HIor

H 150 if60 2.0HZ D > I 500 0.3D - -

H3 0.25Dbut not 0.3D - - - 2.5

less[han 100

HSt tOO iF O.ID 50 50 85 2.0

HS D " I 500;or

HS2 150 iF 0.3D 60 60 90 2.5D > t 500

HS3 0.3D 70 70 95 4.0

t See FIgures 14 [0 17.t In applies to cohesionless materials, Rn [0 cohesive materials. See also Clause 8.• See Commentary.

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19 AS 3725-1989

where

P, = the hydrostatic test pressure determined inaccordance with AS 1392

Pw = the maximum internal working pressure,induding allowance for hammer and otherdynamic effects

Equation 9.

T. ;;, I.5(W,IF + E Wq l1.5) (9)

10.4 Test loads for reinforced pipes subject tointernal pressure. For reinforced concrete pipesoperating under external loads and for which therequired internal test pressure is greater than 100 kPa,the test cracking load (T,p) shall be calculated fromEquation 10.

and l.2Pw <;;; P, <;;; 2.4Pw

(a) the test cracking load (T,) shall be calculated fromEquation 8

T, ;;, W,IF + E Wq/l.5 (8)

where

W, is determined in accordance withClause 6.3;

Wq is determined in accordance withClause 6.5;

F is determined in accordance withClause 9.1.2; and

(b) the test ultimate load (T.) shall be obtained fromAS 1342 for the appropriate pipe size and a loaddass corresponding to the value of T, determinedin accordance with Item (a) above.

10.3 Test load for unreinforced pipes not subject tointernal pressure. For unreinforced pipes not subjectto internal pressure, the test load shall be taken asequal to the test ultimate load (T.) calculated from

T,p;;' (W,IF + '" [P, ]'13... Wql1.5)PI - Pw

,

... (10)

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AS 3725-1989 20

NOTES

•

1

~

I

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