www.cpaa.asn.auConcrete Pipe Associationof Australasia

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4~

AS 3725 Supp1-1989

AS 3725 Supplement 1-1989,

Loads on buried concrete pipes­Commentary

(Supplement to AS 3725-1989)

STANDARDSAUSTRAUA~

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4~

AS 3725 Supp1-1989

AS 3725 Supplement 1-1989,

Loads on buried concrete pipes­Commentary

(Supplement to AS 3725-1989)

STANDARDSAUSTRAUA~

This Australian Standard wa 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 are kept up-to-date by the issue of amendments or new editions as necessary. Itis important therefore that Standards users ensure that they are in possession of the tatest edition, andany amendments thereto.Full details ofall Australian Standards and related publications will be found in the Standards AustraliaCatalogue of Publications; this information is supplemented each month by the magazine 'The AustralianStandard', which subscribing members receive, and which gives details ofnew publications, new editionsand amendments, and of withdrawn Standards.Suggestions for improvements to Australian Standards.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 86014.

AS 3725 Supp1-1989

AS 3725 Supplement 1-1989,,

Loads on buried concrete pipes­Commentary

(Supplement to AS 3725-1989)

First published as AS 3725 Suppl-1989.

PUBLISHED BY STANDARDS AUSTRALIA(STANDARDS ASSOCIATION OF AUSTRALIA)1 THE CRESCENT, HOMEBUSH, NSW 2140

ISBN 0 7262 5946 2

A 3725 Suppl-1989 2

PREFACE

Thi Commentary was prepared by the Standards Australia Committee on ConcretePipe. It i intended that it be read in conjunction with AS 3725, Loads on buriedconcrete pipes, but does not form part of that Standard.In revi ing CA33-1962 the committee considered it desirable that only necessaryrequirements be detailed in the new Standard and that any additional explanations,advice or comments (based on experience gained over the years) be brought to theattention of the design engineer and other users of the Standard by this Commentary.It is not intended that the Standard should be interpreted as preventing the use ofmethods of load assessment other than those specified, as indeed such alternativemethods will possibly be required for circumstances not covered by the Standard.However, the committee considers that in the more usually encountered situations,the methods outlined in the Standard are those most acceptable to all concerned,due to their relative simplicity and the length of satisfactory experience so far obtainedin their application.For ease of cross-reference, clause numbers and titles used in the Commentary arethe same as those used in the body of the Standard but are prefixed with the letter C.Figures, however, are designated Cl, C2 etc, and do not correspond to those in theStandard.The clause numbers of this document are not sequential because if nocommentary is required the clause has been omitted.References noted in the Commentary text are listed at the end of the Commentary.Appendix A of the Commentary contains a number of examples illustrating theapplication of the Standard to the selection of an appropriate pipe from AS 1342or AS 1392. The examples are in the form of typical selection problems each followedby a worked solution.

CONTENTS

Cl SCOPE AND GENERALC4 DEFINITIONSC5 NOTATIONC6 VERTICAL LOADS ON PIPESC8 COMPACTIONC9 PIPE SUPPORT AND BEDDING FACTORSCI0 TEST LOADS

REFERENCES

APPE DICESA EXAMPLES OF THE APPLICATIO OF PROVISIONS

AS 3725

B U IFIED SOIL CLASSfFICATION SYSTEM

Page

33449

1012

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© Copyright - STANDARDS AUSTRALIA

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Care should be taken (0 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 of material in print form or in computer software programs (0 be used commercially, with or without payment, or incommercial contracts is subject (0 the payment of a royalty. This policy may be varied by Standards Australia at any time.

3

STANDARDS AUSTRALIA

Australian Standard

Loads on buried concrete pipes-Commentary(Supplement to AS 3725-1989)

AS 3725 Suppl-1989

Cl SCOPE AND GENERAL. The main purposeof the Standard is to provide an agreed basis fordetermining the vertical working loads on installedreinforced and unreinforced concrete pipes and torelate this to the loads applied to sample pipes in thestandard load tests, so that an appropriate 'strengthclass' of pipe can be selected from AS 1342 orAS 1392, as applicable, which will be suitable for theparticular field application.

Designers should be aware that installed pipes may alsobe subjected to non-vertical loads of considerablemagnitude (e.g. at the toe of a slope). The vertical andhorizontal components of such loads should becarefully assessed and appropriate action taken toensure that they can be resisted by the pipes andadequately transferred to the foundations.

A secondary purpose of the Standard is to reduce thelarge variety of likely installation conditions and bed­ding choices to a small number of representative types.

Like AS CA33-1962, the Standard is based on thework of Spangler (Reference 3) and others of the IowaEngineering Experimental Station, in relation to trenchconditions. The more recent work of the CaliforniaDepartment of Transportation has been utilized forembankment assessments and this is reflected in higherbedding factors in the Standard compared withAS CA33-1962. Bridge design rules published byANZRC in 1974 (Reference 1) and NAASRA in 1976(Reference 2) and their general acceptance since then,have allowed fuller treatment of railway and highwaylive loads to be presented here.

The most recent research in the United States andelsewhere has centred on computer-aided method ofmathematical modelling and finite-element analysis forboth load and pipe stress assessments. Although thisappears to be the future direction of analysis anddesign, there are as yet insufficient practical dataavailable to justify incorporating the results of theseassessments in a Standard of this nature.Methods of pipe laying and bedding preparation arenot stipulated in the Standard because the continuingand rapid development of specialized earthmovingequipment and procedures would soon render suchrequirements obsolete. However in Paragraph C8,detailed procedures for haunch compaction areoutlined, as experience has indicated this to be one ofthe most difficult aspects of circular pipe bedding.Attention is also drawn to Reference 15 which containsmuch useful information on the subject.

Compaction percentages have been included in anattempt to be more specific with regard to bedding andbackfill compaction requirements. For sidefill thecompaction percentages have been given for bothcohesive and cohesionless soils to emphasize that somemeasure of cohesiveness is acceptable in the select fill.This policy has been adopted having regard to the highcost of imported material and to the ever-increasing

range of compaction equipment which makes itpossible to use effectively a wider range of materials.Bedding shaped to fit the outside diameter of the pipes,which was specified in AS CA33-1962, has now beenomitted as there has been a definite trend away fromthis in Australia.

C4 DEFINITIONS.Bedding. See Clause C9. ,

Bedding factor. See Clause C9 for derivation andClause CIO for application.Fill. The term 'fill' is used throughout with aqualifier indicating particular requirements as follows:(a) Backfill or embankment fill. The Standard deals

with the backfill and embankment fill from theaspect of pipe performance only. In installationsinvolving road and railway embankments, ortrenches through urban areas, the stability criteriafor the finished surface above the pipes mayimpose more restrictive requirements on the fillspecification.

(b) Ordinary fill. The restrictions on size and per­centage of stones in ordinary fill are to facilitatecompaction in restricted areas and to limit damageto the pipes during placement apd compaction.

(c) Select fill. The relevant classification informationfrom Appendix D of AS 1726 has beenreproduced as Appendix B of this Supplement.Select fill covers material classed as 'coarse-grainedsoils' in the 'Unified soil cia ification' with theexclusion of the silty-soil classes OM (silty gravels)and SM ( ilty sands). Such materials contain morethe 50010 of hard granular material (usually sandor gravel particles greater than 0.075 mmdiameter) and less than 50% of clay materials.Closer grading limits are given in Clause 9.2 forselect fill suitable for use in the pipe support zones.

Foundation. Pipelines are installed for manypurposes and in a variety of naturally occurringconditions. The foundation material must be able tosupport the loads placed on it and should be carefullygraded or excavated to provide an even bed andmaintain alignment of the pipes. The trench widthshould be the minimum necessary to permit the pipesto be properly laid and the fill compacted.Very soft or expansive clays, irregular or fragmentedrock, and saturated soils, particularly those containingaggressive groundwaters, are all unsuitablefoundations and should be avoided. Where avoidanceis impracticable, most of these situations may usuallybe overcome by adequate drainage of groundwater,removing the unsuitable material and replacing it withcompacted select borrow material, cement-treated soils,or concrete. Where some or all of such actions are notpossible, it may be necessary to have recourse to piling(see Clause C9.3).

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AS 3725 Suppl-1989 4

Since foundation conditions may vary considerablyalong a pipeline, specifications for pipelaying shouldprovide for over-excavation of unsuitable foundationmaterial and specify the replacement material requiredto form an acceptable foundation. This replacementmaterial should preferably be non-cohesive materialthat resists washing (not more than 150/0 less than0.075 mm) and be free from perishable material andmaterial aggressive to concrete. Alternatively a cement­treated soil or concrete working base can be used asthe replacement.

Figures 14 to 17 in Clause 9 give appropriate depthsto foundation level from the bottom of the pipe.Installation condition. The various equations givenin the Standard for calculating dead loads due to fillmaterials, were derived from load conditions asso­ciated with particular configurations of an installation.These configurations have been traditionally classifiedon the basis of the relative levels of the top of thefinished formation and the top of the pipe with respectto the level of the adjacent ground surface, which canbe most clearly seen in a cross-section of an installation(see Figures 2 to 6). Thus embankment or trenchinstallation conditions are distinguished by cross­sections where the finished surface is respectively aboveor at the level of the adjacent ground surface, andpositive or negative projection conditions are distin­guished by cross-sections where the top of the pipe isrespectively above or below the level of the adjacentground surface.Overlay zone. The purpose of the overlay zone is toprotect the exposed portion of the pipe from directphysical damage from construction activities whichfollow compaction of the support material around thelower part of the pipe. Ordinary fill is quite satisfactoryfor this purpose but more finely graded material may

be used if convenient. The term 'overlay', as well asbeing an apt descriptor, was chosen to be consistentwith other pipe Standards, namely AS 2032.

Settlement ratio. See Clause C6.3.5.

CS OTATIO

w The actual unit weight of the fill material shouldpreferably be known or measured prior to com­mencing calculations (see Clause 6.2) and a designvalue assessed. In the absence of more specific datathe values given below may be used for assessmentpurposes. These are 'rounded averages', relating tothe types of soils noted in the figures, based onvalues given variously in References 4 and 5.

Wet clay 20 kN/m3•

Clayey sand 18 kN/m3•

Loose granular material 16 kN/m3•

C'e, C 'n The prime superscript has been used withthese symbols in the Standard to indicate that thecoefficients are different from correspondingcoefficients attributed to Spangler (see also C6.3.3).

C6 VERTICAL LOADS 0 PIPES.

C6.3 Working dead loads due to fill or in-situmaterials.

C6.3.2 Trench condition. Where loads aredetermined from Equation (1), it should always beborne in mind that the values of Ct obtained fromFigure 7 allow for the development and maintenanceof a beneficial friction between the trench wall and thefill material in the trench. If for some reason thisfriction is decreased or not developed, the load on thepipe will be greater than that given by Equation 1.

43Bo

2

J II I 'I /J

I / / V Ja ,t "I.'" "I rvc?La ":- I') It) a

!}-,," ,,'" 'if--.'1 II/~ ~ Q V ,~I,r., ,';'j ,r., ,r., ....'"

I / / / / 1// I V If J /

If / / / I /"

/ If I J'I V

,/

1/ I J / / /,

J V if) / ./,.

/ / V~~L.~

I I 'h~~

I~~~ Kj.L =K~ = 0.165

P,

o1

2

4

6

Ho

8

10

12

14

FIGURE C1 TRANSITION POINT BETWEEN TRENCH AND EMBANKMENTLOADING CONDITIONS

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5 AS 3725 Suppl-1989

(C /,,) in the following Clause are the Spanglercoefficients presented in a more convenient form. Theprime superscript has been used to emphasize thedifference between these coefficients and the originalSpangler coefficients (Ce) and (Cn) (Ref. 3).

In Figure 3 'natural surface' can be the level of eitherundisturbed ground or equivalent built-up andcompacted fill. To be considered equivalent, the built­up compacted fill would have to be select fillcompacted to a minimum of 95070 (RD) for a minimumdistance from each side of the pipe trench as specifiedin Clause 9.2.3.1.

C6.3.4 Embankment condition (negative projectionor induced trench).

(a) Negative projection. This installation condition,which is shown in Figure 4(a), often occurs wherepipelines requiring flat gradients pass throughundulating terrain, resulting inthe pipes being laidin a shallow trench and su~equently covered byan embankment.

There are a number of benefits inherent in thiscondition and depending on the extent to whichadvantage is to be taken of them, the trench maybe filled with compressible material or compactedfill.

Having regard to the commentary on the inducedtrench condition in (b) below, it is clear that anegative projection embankment condition can bemade to operate in an identical manner. Indeed,if full advantage is to be taken of the loadreduction offered by Equation 3, then straw balesshould be specified for the compressible material.

Loose fiII may be specified for the compressiblematerial if some load reduction is desirable. Noallowance should be made for it reduction in theload calculations, as the compressibility of thismaterial is indeterminate (in load calculations anassumption of C/e = 1.0 would be reasonable).However for large values of H/E (say 3 andabove), if it is desired to take the trench effect intoaccount, then a suitable procedure is described inReference 16.

Where low embankments are required andlocalized subsidence would be unacceptable,compacted fill should be specified for the trench.

(b) Induced trench condition. This installationcondition, which is shown in Figure 4(b), can beused with benefit for pipes under highembankment fills.

To obtain this condition, the embankment isconstructed in the normal manner to a level somedistance above the top of the pipe. A trench is thenexcavated part-way through the fill above the pipe,filled with straw bales and the construction of theembankment continued normally to its full height.Alternatively, the straw bales may be placed overthe pipe and the embankment constructed aroundthem.

As the height of fill above the trench increases,the straw bales are compressed, thereby inducingfrictional forces between the soil column above thetrench and the adjacent compacted fill. This resultsin a reduction of the effective load on the pipe ina manner entirely analogous to that in the trenchcondition.

Decreased development or non-development mayoccur if, during construction, withdrawal of a trenchwall support system (shoring and/or sheeting) isallowed to destroy the contact between the wall andthe fill or if the area is subjected to prolonged heavytraffic vibrations. Designers should therefore take intoconsideration the construction techniques andregulatory requirements likely to apply in the particularproject and/or location and adopt appropriate beddingfactors accordingly. The design of a pipeline assumesa particular trench width. If anything occurs toincrease this width, then referral should be made tothe designer.

The Clause specifies that the load in the trenchcondition shall be taken as the lower value derivedfrom either the trench or the embankment formula.Generally speaking, as a trench becomes wider, thefrictional forces noted above become a decreasingproportion of the total vertical forces acting on thepipe until a width is reached where embankmentconsiderations begin to dominate. The theoreticaltransition point between trench and embankmentloading conditions may be obtained from Figure C1.Where sloping trench sides are used, calculations mayindicate an increase in load over vertical trench sides(see Ref. 12). However, for most practical applicationssuch increases are not significant and are usuallyneglected.Since the load on the pipe and the cost of excavationboth increase with increasing trench width, economyof design dictates a trench width as narrow aspracticable.The practical considerations governing minimumtrench width are-(a) the maximum external pipe diameter;(b) the thickness of the trench wall supporting system,

where required; and(c) the clearance between the outside of the pipe and

the trench wall or wall support system, which mustbe sufficient to accommodate the operator andequipment necessary to compact the bedding andhaunch materials.

For pipes of diameters too large to allow sidecompaction to be carried out by operators standingon top of the pipes, it is generally considered that atleast 0.3 m clearance on either side of the pipes isnecessary if effective sidefill compaction is required,and many mechanical compactors need 0.6 m forsatisfactory operation. For these reasons the figures inthe Standard show a side clearance of not less than0.2D or 0.3 m, whichever is greater.In all instances the choice of trench width must be acompromise between the demand for minimumexcavation/backfilling and adequate work space wheresidefill compaction is important for the performanceof the installation as a whole.The trench width specified in the design, directlyinfluences the load on the pipes and hence their loadclass for a particular installation. It is thereforeimportant that the consequences of any deviation inthe field from the specified trench width be addressed.Such deviations can easily occur as a result of trenchwall collapses or changes in the method of excavation.Installation specifications should specifically deal withthis issue.C6.3.3 Embankment condition (positiveprojection). The coefficients (C /e) in this Clause and

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A 3725 uppl-1989 6

where

Sm compression of the side column of soil ofheight D

Although the benefits of this method are well provenelsewhere (notably in California), induced trenchconstruction has not been used to any great extent inAustralia. This is probably due to some sub idencefailures, caused by inadequate constructionprocedures, experienced in the early history of themethod. It has been subsequently demonstrated thatdelayed subsidence will not occur if the embankmentis properly compacted throughout and of sufficientheight to compress the bales. To ensure this, someauthorities set a minimum embankment height of 15 mfor the use of the induced trench method and sinceembankment fill below 15 m can be readily handledwithout resort to this approach, the limitation seemsreasonable. However, successful induced trenchinstallations have been made with embankment heightslower than 15 m.

C6.3.S Settlement ratio. This ratio refers toembankment conditions and is defined by thefollowing equations:

rs

= (Sm + Sg) - (Sf + de)

Sm

rs

for positiveprojection; or

for negativeprojection

Sg = settlement of the natural ground surfaceadjacent to pipes

Sf settlement of the pipes into their foundation

Sd compression of the fill material in the trenchwithin the height-p I Bd

de = deflection of the vertical diameter of thepipes

(see Figure C2).

Depending on whether r is po itive or negative, theshear stresses between the soil prism above the pipesand the adjacent soil columns will be acting down­wards or upwards on the prism. The implication ofthis difference is discussed in more detail inReference 3.

C6.3.7 Jacked or bored pipes. When establishingthe strength requirements for jacking pipes, the jackingforce as well as the vertical external load should beconsidered.

The effect of this on the pipe specification is dealt within Reference 6. As a general rule the cross-sectionalarea of the pipe joint should be large enough to limitthe compression stress to between 12 MPa and 15 MPaf9r packed joints, assuming concentric compression.This value allows for some measure of eccentricity inthe transfer of the jacking force through the joint.However, a higher stress may be used in speciallycontrolled circumstances, or where a detailed stressanalysis of the joint is carried out.

Top of embankment Top of embankment

-r'=~.0~--OL~.9~~~_~~~t!~f!l~~~---I II I

I tit Shearing forcesH': : induced by

I I

HI I I settlementse I I

i Bd :I' , I Sg Natural

Sd+Sf+dc : groundm-:~'- r-+--777C'hn sur face

I IH=H+pBd

Shearing forcesinduced bysettlements

~::=~ Initial elevation~ Final elevation

H

IH-

H__e

Plane of equal settlement-----r---------,---------II

titIIIIIIIIIII

I I-----r--~--'------

I /~----~~, i Critical

I '\ planepBc S

B 'e 9 r Natural

J+-'/717 ground

----=====~...;;;.;~~=t~',VII sur face

Sf

lal Positive projectionembankment

(bl Negative projectionembankment

FIGURE C2 SETTLEMENT RATIO TERMS

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7 AS 3725 Suppl-1989

TABLE ClA14 and T44 WHEEL LOADS

TABLE C2IMPACT FACTOR

LoadNAASRA Wheel contact dimensions

vehicle load (P) mkN

a b

AI4 70 0.2 0.5

T44 48 0.2 0.4

At a given depth below the road surface, the averageload intensity is taken to be the greater value obtainedfrom these arrangements, using Equation 6 and anappropriate value of the impact factor (a) taken fromTable C2.

1.31.21.11.0

Impact factor(a)

Height. ofcover (H)

III

o to 0.300.31 to 0.600.61 to 1.0

> 1.0

Where AASRA specifications are not mandatory,such as within private property, experience hasgenerally hown that for earth covers between 0.3 mand 0.6 m, satisfactory performance can be achievedby a design u ing the arne di tribution assumptionsas illustrated in Figure 10.. In these circumstances theuser must accept responsibility for the design methodadopted.The effect of a pavement has not been considered inClauses 6.5.2.2 to 6.5.2.4 mainly because it might beremoved at a later date, even if only temporarily.The effect of a rigid pavement (concrete) is todistribute the load over a wider area than in the caseof unpaved areas. The influence of flexible pavementsis small and can usually be ignored.Design load calculations for pipes bedded under rigidpavements are shown in Reference 7, which forms thebasis for the treatment of this subject in Reference 8.

C6.5.2.3 NAASRA vehicle 10Vds. Relevant wheelarrangements for the AASRA Al4 and T44 standardvehicle loadings are given in Figure C4.The values of the appropriate wheel loads and thedimensions of the load contact areas are obtained fromTable Cl.

Figure II was compiled using the assumptions givenin Clause C6.5.2.2 and the foregoing loads and loadarrangements.C6.5.2.4 Working loads due to other roadvehicles. Equation 7 may also be used for calculatinglive loads from other average load intensities, if theappropriate value of q, obtained from the relevantclauses, is substituted in the equation.The use of the effective length (Le) recognizes theability of a pipe to spread the load over the length ofits supporting bed.C6.5.3 Railway loading. The load intensity/depthcurve shown in Figure 13 is based on data fromReference 9. The data were modified to suit theANZRC Metric Cooper M250 track loading shown inFigure C5.

C6.4 Working loads due to superimposed deadloads. Concentrated dead loads applied to thesurface close to pipes should be avoided whereverpossible. However, if it is nece sary that a pipe passclose under or closely adjacent to uch a load, a load­relieving structure, which tran fers the load directlyto a level at or near the pipe invert, should always beused. If this is not feasible and concentrated surfaceloads will be transmitted to pipes through a reasonabledepth of fill or natural ground, the de igner shoulduse accepted methods of soil mechanics and structuralanalysis to determine the effect of the load on thepipes, taking account of any proposed futureadditional loads.

C6.5 Working loads due to superimposed live loads.

C6.5.1 General. The live loads of principal concernin pipe design are the concentrated surface loadsresulting from roadway, railway and constructionvehicles. Live loads resulting from the passage of heavyservice or emergency vehicles over the pipes will alsoneed to be considered in off-road or off-rail areas.

1mpact loadings, particularly those caused byconstruction equipment, may increase considerably inthe transition from smooth to rough surfaceconditions. Designers should take into account thecontrols on heavy equipment movement and on thesurface profiling that will be in place during andsu bseq uent to construction.

Live loads from cars and pedestrians in carparks andpedestrian thorough fares, etc, are usually negligiblein relation to the loads due to the fill materials overthe pipes and have therefore not been considered inthe Standard.

Where however it is necessary to consider uniformlydistributed live loads of this nature, appropriate valuesof the loads may be obtained from AS 1170, SAALoading Code, Part 1: Dead and live loads. These maythen be treated as an equivalent height of fill as foruniformly distributed dead loads and the working loadon the pipe calculated in accordance with the relevantinstallation condition. The portion of the test loadfrom these causes would be obtained by dividing theworking load thus calculated by 1.5, this being thebedding factor for live loads.

C6.5.2 Road vehicle loads.C6.5.2.2 Distribution of wheel loads. For coversgreater than 0.6 m, the assumptions on which pressuredistributions resulting from road vehicle wheel loadsare based, are given in the Clause. These are based onela tic theory and the appropriate Boussinesqequations.

For a single wheel load (i.e. where G = 0),L 1 = b + I ,45H. For multiple abnormal wheel loadsand axle configurations, the appropriate distributedload should be determined in accordance withFigure 10 and Equation 6. The same principles maybe applied to loads from vehicles in adjacent lanes (seeFigure C3).

For covers less than 0.6 m the whole wheel load shouldbe assumed to bear directly on the pipe but may bedistributed over the effective length, Le, as defined inClause 6.5.2.4. For small diameter pipes, this can leadto high working loads which have to be resisted notonly circumferentially but also longitudinally in thedirection of the pipes. Uniform bedding conditions aretherefore of considerable importance in these circum­stances.

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AS 3725 Suppl-1989 8

/\ /'\ ,'," " ", , , , , ,

I \ I \ I \------~-------~--~------~--~-------~-------

L1 = I: (G +b) + 1.45H

FIGURE C3 LOADS FROM VEHICLES IN ADJACENT LANES

Direction of traffic flow. ~

0.6

1.8

0.6

bJl--~~a~ T

I 1.2 i

-~--·I

0.6

1.8

0.6

(a) A14 vehicle (b) T 44 vehicle

DIMENSIONS IN METRES

FIGURE C4 NAASRA A14 AND T44 WHEEL ARRANGEMENTS

Axleload

lON,-

0000lOlOlOlON N N N

lO lO lO lON N N N<D (!) (!) (!)T- T""" ,..- T"'"

lON,-

0000lOlOlOlON N N N

lO lO lO lON N N N(!) (!) <D (!),-

lO lON N,-(") (")

00

wOR0000() () () () Ln0000

2.5 1.5 h.5 .5 2.8 1.5 1.8 1.5 2.5 2.5 h.5 1.5 1.5 2.8 .5 1.8 h.5 1.5

Ln

Axlespacing

Axle loads shown in kilonewtonsAxle spacings shown in metres

FIGURE C5 METRIC COOPER M250 TRACK LOADING

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9 AS 3725 Suppl-1989

Track gauge Nominal sleeper lengthmm mm

1600 (broad) 27501435 (standard) 24401067 (narrow) 2150

Height from topof rail to top of Load intensity

pipe (H) k 1m2

m

TABLE C4COMMO LY USED SLEEPER LENGTHS FOR

VARIOUS TRACK GAUGES

responsibility to ascertain the type of equipment likelyto be used and to determine the loads this equipmentwould transmit to the pipes at various depths of cover.For the selected pipe, minimum depths of cover atwhich various items of equipment or maximum loadsare permitted to travel over the pipes can then be set.Adequate provisions, in the form of instructions,supervision or contractual requirements, should thenbe made to ensure that these design conditions are metduring installation.

C8 COMPACTION. Since disturbed natural soilsexhibit a high degree of variability in both the extentand rate of consolidation under load, thorough anduniform compaction of fill material under, over andaround pipes to at least the degree nominated isessential for maintaining-

(a) required grades and alignments, by compaction ofthe material below the invert and along the sidesof the pipes; I

(b) the required degree of' circumferential andlongitudinal support, by compaction of thematerial below the top of the pipe; and

(c) required surface levels, by compaction of allmaterial between the foundation and the finishedsurface.

To achieve the desired compaction, the beddingmaterial should be laterally contained. In a trench, thiscontainment is provided by the trench walls; in anembankment, however, sufficient lateral support willgenerally not be available. In such cases and wherepossible, a shallow trench can be cut in the foundationmaterial to contain the required depth of bedding.Where the relative levels of the pipe invert and theadjacent natural surface precludes trenching of thefoundation, the embankment may have to beconstructed to a height approximately equal to the pipediameter and the containment trench then cut throughthe compacted embankment fill.

Because of the relatively high costs involved inobtaining, placing and compacting bedding material,the designer should examine carefully the economicconsequences of choosing a high bedding factoragainst the alternative of a lesser depth andcompaction of bedding with a consequently lowerbedding factor and possibly stronger pipe.

As noted previously in Clauses C4 and C6.3.4, wheremaintenance of a smooth surface is essential(roadways, aircraft runways, etc), proper compactionof the fill materials over and adjacent to the pipes willbe required.

In order to achieve adequate compaction in the field,fill material should be placed and compacted inrelatively thin layers. For ordinary fill (no stones largerthan 150 nun), the layer thicknesses should not exceed200 mm. For select fill (no stones larger than 75 mm),the layer thicknesses should not exceed 150 mm. Themoisture content of cohesive fill should also be keptwithin a specified range, usually taken to be 85 percentto 115 percent of the optimum moisture content of thematerial. Where physically possible, field tests asoutlined in AS 1289 should be regularly used tomeasure the degree of compaction being achieved. Inareas such as beneath the pipe in the haunch zone, itis not possible to conduct tests such as AS 1289.E3.1due to limited headroom. Yet, in such areascompaction can be extremely critical and it is suggestedthat a dynamic cone penetrometer, such as that

1286740

30242013

LO1.82.7

3.44.04.9

6.4

TABLE C3LOAD INTENSITY FOR M250 RAILWAY LOADS

INCLUDING IMPACT

Table C3 gives point values for the curve of Figure 13,calculated as above, for the standard gauge track(1435 mm) incorporating an impact factor (a) whichvaries linearly from 1.3 at I m depth to 1.0 at 3.4 mdepth and is constant thereafter. The values wouldhave to be modified for other track gauges using theappropriate sleeper lengths given in Table C4.

Because of the clearance requirements for paralleltracks, increases in load intensity from adjacent tracksmay be neglected.Intensities from other railway loadings on the samegauge track may be obtained from Figure 13 by simpleproportion.For example, if intensity is required for a height ofcover of 3 m for M220 loading-

From Figure 12 for M250 loading, q = 36 kN/m2

at H = 3. Hence for M220 loading,

q = 36 x '220250

= 32 kN/m2

Pipes with shallow cover under railway tracks shouldbe avoided as they are liable to damage from trackmaintenance equipment.C6.5.4 A ircraft loads. Aircraft loadings varyconsiderably depending on the type of aircraft andpavement construction. This is a specialist area ofdesign and reference should be made to the relevantdesign requirements of the Regulatory Authority andspecialist literature such as References 7 and 10.C6.5.5 Construction and other equipmentloads. Live loads from construction equipment is anessential consideration in the design or selection ofpipes as they may constitute the maximum designloading. Some Authorities have determined minimumcover requirements for passage of constructionequipment, and designers may be able to use suchinformation for guidance. However, it is the designer's

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AS 3725 Suppl-1989

described in AS 1289.F3.2, be specified to be used onan angle to probe adjacent to the haunch. It wouldbe necessary to calibrate the cone, operating at thesame angle in the same material, with a known degreeof compaction.

It i important that all support material is compactedto the minimum density pecified in Table 5 a thecompaction influences the relevant bedding factors.

The bed and haunch zone material is usually placedand compacted in two stages. The first stage consistsof the bed zone, the second is the haunch zone. Thebed zone can be compacted by most conventionalmethods (tamping, rolling, vibration) but for thehaunch zone the following guidelines are given:

(a) Material complying with the grading limits inClause 9.2.2.2 may be placed and compacted inone operation by aturation and vibration.

(b) Bedding materials with a fines content in excessof the preferred grading should be stabilized withcement and compacted by vibration. The cementcontent both enhances its compaction qualities andstability when set.

Alternatively, the bedding factor may be reducedin accordance with Clause 9.3.2.

(c) Sound crushed rock can be an excellent materialfrom a stability point of view, even if gap graded.Its compaction qualities may be enhanced bycement stabilization.The disadvantage with a gap graded material isthat it has to be surrounded by a suitable geotextilematerial, if used in connection with foundationmaterials containing fines which can leach into itsvoids.

(d) Where cement stabilization of the beddingmaterial is required, soil/cement ratios rangingfrom 25 to 8 may be used, giving 28 daycompressive strengths from 1 to 5 MPa. (SeeReference 11.) There is a slight indication of abedding factor increase with increased compressivestrength, but generally the cement i used toenhance the placing and compaction qualities ofthe material and the cement content should bechosen with this in mind.

C9 PIPE SUPPORT AND BEDDING FACTORS.C9.1.1 Pipe support. The purpose of usingcompacted material adjacent to the pipe is to ensureuni form longitudinal support for the pipeline andwhere bedding factors in excess of unity are required,to provide appropriate support for the lower half ofthe pipe's circumference and sides as opposed to justa line load support.

The above considerations and those in Paragraph C8highlight the two aspects of the concrete pipe beddingwhich constitute the dominant influences on thestructural performance of the pipes, namely:

(a) The extent and degree to which an even anduniform support is provided under the haunchesof the pipes.

(b) The effectiveness of the lateral restraint providedby the side support .

When comparing the bedding factors applicable to thedifferent support types, it becomes obvious that if ahigh degree of haunch support can be effected togetherwith a very effective side suppor.t, then very highbedding factors can be expected.

10

However, the practical difficulties in achieving this areconsiderable and the degree of field supervisionrequired to ensure its consistent achievement is veryhigh.

The long-term stability of the installation must becon idered when selecting materials for the supportzone, particularly for a trench condition. Theexcavation of a trench on a grade in imperviousmaterial may constitute a drainage channel and anymaterial placed in the trench must therefore resistscouring. Material consisting mainly of fine sandswould be unsuitable in these circumstance.

American practice under the influence of Spangler hasfor decades been to provide shaped beds, i.e. to eurvethe foundation to fit the outside diameter of the pipeswhen placed on a thin cu hion of sand or cement­treated soil. This practice, however, is very seldomused in Australia. (See Reference 3.)

C9.1.2 Bedding factors. The effect on the load­carrying capacity of installed pipes, due to live loads,has historically been hown to be virtually independentof the type of bedding used or the in tallationcondition. Consequently, the bedding factor for liveloads has been taken in the Standard as a constantvalue of 1.5 for 'all live loads and installationconditions.

C9.2 Support types.

C9.2.1 Type-U support. Type-U support is in­tended for minor reticulations in small diameter pipe ,such as shallow drainage lines crossing private pro­pertie , or where the pipe will not be subjected tosignificant traffic loads. Rock foundations need to becovered by a soil material and similarly it is customaryto cover earth foundations to ensure that no bouldersor rock outcrops are present immediately below thepipes. If the absence of rocks or boulders isguaranteed, a separate bedding cushion is not requiredand only grading of the foundation is necessary.

Similarly, the provision of an overlay of 300 mmthickness of ordinary fill ensures that no boulder orlarge rocks can damage the pipe during eitherbackfilling or any subsequent compaction.

C9.2.2 Type-H support. The loads acting on thetop portion of a pipe are nearly always well distributed,irrespective of how the overlay fill materials areinitially placed or compacted. However, thedistribution of the reaction on the bottom part of thepipe depends almost entirely on the extent and degreeof compaction of the loading materials actuallyachieved in the field. Guidelines on this operation aregiven in Clause C8.

Type-H (haunch) support is aimed at reducing thebending effects in the pipe by distributing the reactionto the applied loads over an appreciable arc of thepipe's lower circumference. (This can be likened toreducing the bending in a beam by substituting anequivalent uniformly distributed load for a mid-spanpoint load). For a haunch zone depth of 0.3D, themaximum effect of distributing the reaction in this wayis a reduction of the bending in the pipe wall toapproximately 400/0 of the bending produced by theline support of the standard load-test. Hence, amaximum bedding factor of 2.5 is specified in Table 5,assuming that the relevant compaction has beenal:hieved.

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ote that for Type-H support, the material in theoverlay zone is specified simply as 'compactedordinary fill' but no degree of compaction is indicated.Thi i because none of lhi material, even thal alongthe ides of the pipe, i relied upon to support the pipein a structural sense.

Type H I and H2 support depend primarily on wellcompacted bed and haunch zones to support the pipe.The materials in these zones therefore needs to becarefully selected to en ure that the requiredcompaction can be achieved and maintained during theeffective service life of the pipe. Select fill whichsatisfie the grading limits of Table 3 should meet thesereq uiremen ts.

The cost of imported materials is high and ofimporting materials which do not exceed the specifiedlimits may possibly be even higher. Materials withgrading curves not lying entirely within the limits givenin the table are therefore permitted, since in any casethey may still be capable of being compacted to therequired density, or if not, may be so compacted ifcement tabilized. Materials with only the finerfraction « 0.15 mm) outside the specified limit areparticularly suited for the latter approach.

Type-H3 support is in effect a concrete cradle. Theuse of concrete cradles, a well as concrete surrounds,is a carry-over from the time when all that could beexpected from concrete pipes was to form a conduitof low and often undefined strength, the tructuralrequirements of the system being largely supplied bythe in-situ concrete. However, the concrete pipecurrently available are capable of satisfying mosttructural requirement . The necessity for concrete

cradle, as a means of increasing the load capacity ofthe pipes, therefore no longer exists.

There are circumstance, however, where a concretecradle may still be used advantageously. For example,it may be used as an alternative to pile foundationswhere a heavy pipeline passes over ground of lowbearing capacity, or in confined spaces where it maybe easier to place and compact fresh concrete than itis to place and properly compact available fill material.In view of this, appropriate bedding factors for Type­H3 support have been included in the Standard.

De igners should be aware that in using concreteupport:

(a) Prediction of the manner of structural interactionbetween cradles and pipes is difficult, if notimpo sible. Usually the upport will be of a lowerquality concrete than the pipe and have differentshrinkage characteristics. Some separation of pipesand cradle should be expected.

(b) The use of a rigid upporr material destroys theflexibility of the pipeline unless properconstruction joints are provided.

C9.2.3 Type-HS (haunch-side) support. As impliedby the HS designation, thi type requires an effectiveside support for the pipe '0 that, depending on thedegree of compaction acl (eved, a bedding factor inthe range of 2.0 to 4.0 may be assumed.

Type-HS supports are best suited for embankmentconditions, where good control of the side fillcompaction is most readily achievable. The new Type­HS3 upport, with a maximum bedding factor of 4.0,ha been introduced primarily for high embankmentituations.

11 A J725 uppl-1989

HS support are equally applicable to trench condi­tions provided that the pecified ide compaction canactually be achieved in the field. However, it isexpected that HS uppon will be u ed in trenche onlyif circumstance require a bedding factor in exce s of2.0. In uch case , considerable care will need to betaken to en ure that the required ide compaction, andhence effective uppon ha been obtained, e peciallyin deep narrow trenches where trench wall upportare required.

The effectiveness of the haunch and side support al 0

depends on the lateral re traint offered by the trenchwall. Disturbed trench walls, or trenches dug inunstable materials cannot be counted on to providethe degree of restraint as umed in the HS beddingfactors. Hence the restrictions placed on the materialsin the trench walls before considering the side zonesto be effective.

Note that for HS supports, eitfier H I or H2 bed andhaunch zone dimensions and materials are specified,i.e. H I zones for HSI support, and H2 zones for HS2and HS3 upports. The latter i po ible becau e themore effective the side support becomes, the less thesignificance of the bed and haunch support distri­bution, as the position of the maximum bendingmoment hifts away from the invert. This point habeen confirmed by tests on Type-HS3 installationwhich showed no difference in the load-bearingcapacity of the pipes when they were bedded on ashaped or a flat bed.

C9.3 Bedding factors for dead loads. Thecorrelation between working load on installed pipeand test loads, represented by the bedding factors givenin the Standard, have been established from acombination of theoretical ,considerations,investigations of the researcher noted in Clause Cl,and more than 30 years of observations of pipes inservice. More recent investigations, involvingcomputer-aided mathematical modelling and finite­element analysis techniques, indicate that ome of the evalues may be more conservative than has beenassumed in the past. However until such time asufficient alternative evidence is available, therecommended relationships will continue to safelyallow for both the incompletene of our knowledgeof oil-pipe interaction and the inherent variability ofthe materials and methods used in the in tallation ofconcrete pipes.

For Types-U, -H and -H upports, Table 5summarizes the criteria to be satisfied if a particularbedding factor is assumed. Before assuming themaximum value, however, the designer will need tosatisfy himself that the required minimum degree ofcompaction in the various zones will actually beachieved in the field. A well-written workspecification, with provision for adequate site te tingand supervision, would usually be necessary for suchan as umption, otherwise a lower value than themaximum should be chosen.

Note that Clause 9.3.2 requires a reduction of 15070 onany maximum value if the fine fraction of the bed orhaunch zone material has a grading curve outside thelimits of Table 3. This is becau e the long term stabilityof such material is suspect unle s it has been cementstabilized.

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AS 3725 uppl-1989

For jacked or bored pipes the bedding factor canusually be as umed to be between 2 and 3, dependingon the degree of over-excavation. If the space betweenthe limit of the excavation and the out ide of the pipesis too large, haunch support can only be effected aftereither considerable vertical deflection of the pipes, orsoil movement. In this case the lower value of thebedding factor should be assumed.C9.4 Other types of upport. Although not coveredby the Standard, other types of pipe support may benecessary in special circumstances.(a) Stabilized bedding. Where accurate alignment on

flat grades is required (e.g. sewer installations), thebedding arrangement illustrated in Figure C6 hasbeen used satisfactorily. Such an arrangementoffers some of the advantages of Type-H3 supportwithout the disadvantages noted in C9.2.2.This method is particularly suitable for heavy,large diameter pipes, even on fairly goodfoundations, as it facilitates the laying of thepipelines to the required tolerances and ensuresstability of grade.The concrete base slab spreads the load over thefoundations and serves as a working platformduring pipe laying. The rest of the cradle is ofcement- tabilized granular material which ensuresthat, if movement occurs, the cradle will crackbefore the pipes but will still continue to providethe upport required for them. The beddingfactors given in Clause 9.2.2.2 should be used.

(b) Piles. Pile foundations are frequently used assupport for concrete pipelines where it is necessaryfor these to traverse unstable ground.As pipes on pile supports are usually subjected toboth high bending and shear stresses, they mustbe pecially designed for such support conditions.Standard pipes are only suitable for such supportconditions if the load on the pipes is limited tolight earth load.

(c) Clay. Clay is generally unsuitable as a means ofproviding stable support for a pipeline.Nevertheless, it may occasionally be necessary touse a clay bedding, e.g. where a pipeline passesthrough the clay core of an earthfill dam. In such

I+-A

12

circumstances, conservative assumptions about thebedding factor must be made.

CIO TEST LOADS.

CIO.I General. For the standard methods of testspecified in AS 1342 and AS 1392, the test pipe issupported at the bottom along it length on one or twoline supports and the load is applied along a line atthe top of the pipe. This produces localized extremesof stress iil the pipe adjacent to the line of the supportand the line of the load, and at right angles to thesepositions.

For installed pipes, the load and usually the support,is distributed over a much larger proportion of the pipecircumference than is the case with the test loads,leading to lower load intensities and more evendistribution of stresses throughout the pipe wall.Consequently, for a given pipe and failure criterion(viz. formation of a particular width of crack, orcollapse), an installed pipe will carry a greater loadthan the test load. The ratio of these loads is definedas the 'bedding factor' which can be seen in Clause 9to be a function of the nature of the applied load andthe nature and extent of the support provided to thepipe by th~ materials in the variou support zones.

CIO.2 and CIO.3 Te t loads for pipes not subject tointernal pressure. The correlation between workingloads and test loads obtained by using the beddingfactor in accordance with Clauses 10.2 and 10.3,defines a deemed to be equivalent relationship betweenthe two loads. On this basis, having calculated theworking load for a given installation condition, theequivalent test load can be determined from Equations8 and 9. An appropriate class of pipe may then beobtained from AS 1342 by selecting, for the requiredpipe diameter, the class whose test load is equal to orgreater than the equivalent test load. Examples of thitype of calculation are given in Appendix A to thisSupplement.

CIO.4 Test loads for reinforced pipes subject tointernal pressure. This Clause is intended tosupersede Appendix F of AS 1392-1974 as it wasconsidered more appropriate for these requirementsto be included in the loading Standard.

Timberwedges

Timberblock

Cementstabilizedgranularmaterial

SIDE VIEW SECTION A-A

FIGURE C6 STABILIZED BEDDING

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13 AS 372SSuppl-1989

Acceptance of pipes by proof testing implies that forin-service conditions of s.imuItaneous external loadsand internal pressure, the pipes hould be tested in acorresponding manner. Such tests, however, are bothexpensive and difficult to perform. It has thereforebeen customary to substitute separate external loadtests and hydrostatic pressure tests and to utilize an inter­action formula to a certain a combination of workingload and pressure for which the pipe will not leak.

The use of Equation 10 for this purpose is traditionalfor many pipe materials. The rationale leading to itsadoption for concrete pipes is given in References 13and 14. Whilst these references deal mainly withprestressed concrete pipes, Reference 14 endorses itsuse for 'other types of concrete pipes' and it has beensuccessfully used for reinforced pipes in Australia formore than a decade.

As can be seen from Equation 10, the relationshipbetween the external test loads and internal pre suresis a fractional power function which can be writtenin the form-

y = (I_X)1I3; O~ x;';; 1.0

where

y = Tc/Tcp

x = PwlPr

It should be particularly noted that Equation 10 doesnot yield a unique value of test load for a particularworking load and working pressure, but gives a rangeof values depending on the choice of the ratio ofworking to test pressure, or vice versa. This can be

Tcy=­Tep

O. 4 ~--+---+---I----+,I,L-,.L-/-t-,.L-,L-y~+-',L.,L:.j,L.,L..r~-A---I-~---I

0.2

1.0O.~0.80.70.30.20.1 0.4 0.5 0.6Pwx=-PI

FIGURE C7 LOAD-PRESSURE RELATIONSHIP

0.0

~ 1600.:t:.

-; 1400I-

w 1200a:::::>

1000(J)(J)wa: 800a..I-

600(J)WI-

~400

::::>~ 200x<t::~

0

~

'" ...........

"'- .........i'......, -- r---...r-.. """-- -~ -

400 800 1200 1600 2000 2400 2800200 600 1000 1400 1800 2200 2600 3000

PIPE DIAMETER (D l. mm

FIGURE C8 MAXIMUM PRESSURES FOR REINFORCED PIPES

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clearly seen from Figure C7 where for any value ofthe pressure ratio (x) the external load ratio (y) can varybetween zero and (I-X)1/3.

The extreme values of this relationship are shown bythe ends of the curve in the Figure which indicates that,theoretically at least, the combination cracking load(Tel') would equal the non-pressure cracking load (Te)

only when x = 0, Le. when the working pressure (Pw)

equals zero. For practical purposes however, theeffects of internal pressure are taken to be negligibleif the test pressure (Tp) is not greater than 100 kPa,Hence for reinforced pipes where the working pressure

14

is such that the test pressure is not greater than100 kPa, Equation 8 may be used a indicated inClause 10.2.

Further limitations on the choice of the pre sure ratio(x), are imposed by the inequality given at the end ofthe Clause. This is derived from considerations of theminimum factor of safety on internal working pressurerecommended in AS 1392 and the practical maximumcapacity of a given size of pipe to resist internal pre­ssure as shown in Figure C8. The resulting range ofvalues for 'x' and 'y' permitted by the Standard areshown by the shaded area of Figure C7.

REFERENCES IN COMMENTARY.

1. Railway bridge design manual. Australian and New Zealand RailwayConferences (ANZRC), 1974.

2. Bridge design specification. National Association of Australian State RoadAuthorities (NAASRA), 1976.

3. SPANGLER M.G. and HARDY R.L. Soil engineering. McGraw Hill, 1982.

4. AS CA33, Concretepipelaying design. Standards Association of Australia, 1962.

5. AS 2566, Plastics pipelaying design. Standards Association of Australia, 1982.

6. Pipe jacking. Concrete Pip~ Association of Australia, 1984.

7. Vertical pressures on culverts under wheel loads on concrete pavementslabs. American Portland Cement Association, 1951, Publication No ST-65.

8. Concrete pipe design manual. American Concrete Pipe Association, 1970.

9. Manual for railway engineering. American Railway Engineering Association.

10. Aircraft loads. American Concrete Pipe Association, 1969, Design Data No 15.

II. NUSSBAUM P.J. and CADlENA L. Load factors for concrete pipes beddedin cement-treated soils. Skokie (Ill.): Portland Cement Assn, 1975.

12. Guidelines for static calculations of drainage conduits and pipelines. ATV,December 1984, Work Sheet A127.

13. Journal of the American Water Works Association. November 1950,p. 1059-1064.

14. Journal of the American Water Works Association. January 1963, p.99.

15. Geotechnical Branch Training Manual. Denver, (Col): U.S. Department of theInterior, Bureau of Reclamation, Engineering and Research Centre. Nos I, 2,3 and 7.

16. YOUNG O.c. and TROT J.J. Buried rigid pipes (structural design ofpipelines).London: Elsevier Applied Science Publishers, 19~4, p.58-59.

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15 AS 3725 Suppl-1989

APPENDIX A

EXAMPLES OF THE APPLICATION OF PROVISIONS OF AS 3725

Al INTRODUCTION. This Appendix presents practical problems and relevantcalculations which illustrate how the provisions of the Standard are applied indetermining working loads on pipes and in selecting for these loads the appropriateclass of pipe manufactured in accordance with AS 1342 or AS 1392. The calculationsare presented in an explanatory form to assist first or occasional users of the Standard.The order of accuracy adopted in the calculations is consistent with the accuracy ofthe assumptions on which they are based.

Figure Al illustrates terms relating to the pipe cross-section, which are used throughoutthe examples.

,,I-------+-- Size = nominal internal

Crown ---l-----.. diameter

Obv er t ----/J---/

Inver t ---V.----..

FIGURE A1 PIPE TERMS

A2 EXAMPLE 1.

Problem. A ize 900 mm reinforced concrete drainage pipe, is to be laid in a singletrench through an open paddock. The trench will be excavated entirely in clay whichsatisfies the requirements for ordinary fill. A gravelly sand (GW) complying withTable 3 is readily available nearby. The specification calls for the pipe invert to be5.0 m below ground level, Type-H2 support for the pipe and prohibits the passageof construction machinery or other vehicles over the pipeline. What class of pipe isrequired?

Calculations. Assume the outside diameter, D, of the pipe is 1.0 m. From Figure 15,the width of the trench (B) is the larger of D + 0.6 or 1.4D.

Width of trench, B = 1.0 + 0.6 = 1.6 m.

Depth of fill, H = 5.0 - 1.0 = 4.0 m.

Unit weight of fill, W = 20 k 1m3 (see Commentary, Clause C5).

The working load due to fill for a trench condition is given by the lesser of the valuesobtained from Equation 1, in Clause 6.3.2 and from Equation 2, in Clau e 6.3.3 asfollows:(a) Equation 1 is-

Wg = C1wB2

From Figure 7, for HIB = 2.5 and Curve A for wet clay, Cl 1.9.

Substituting in Equation 1,

Wg = 1.9 x 20 x 1.62

= 97.3 kN/m.

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AS 3725 Suppl-1989 16

= 0.53 m= 2.0 m

HI.

(b) Equation 2 is-

Wg = C'cwDH.

The projection ratio, P = hiD, is equal to 1.0 and from Clause 6.3.5, the settlementratio (r,) for positive projection and earth foundation is 1.0.

Hence r,p = 1.0From Figure 8, for HID = 4.0/1.0 = 4.0 and rifJ = 1.0, C/c 1.66.Substituting in Equation 2,

Wg = 1.66 x 20 x 1.0 x 4.0= 132.8 kN/m.

Since the value for Wg obtained from Equation 1 is less than the value obtained fromEquation 2, this is the value to be used in Clause 10.2.For reinforced pipes, where no internal pressures are involved, the test cracking loadis given by Equation 8 in Clause 10.2 and for no live loads-

Te ~ WglFFrom Table 5 in Clause 9.3, for Type-H2 support, the bedding factor (F) is 2.0. Hencethe minimum test cracking load would be-

Te ~ 97.3/2~ 48.6 kN/m.

Solution. From Table 4.2 of AS 1342, the test cracking load for a 900 mm diameterClass Y pipe is 55.5 kN/m. Since this is greater than the calculated value of Te, aClass Y pipe would be suitable.

A3 EXAMPLE 2.Problem. A size 450 mm concrete drainage pipe is to be laid in a single trenchthrough an open paddock. The excavation is entirely in material which is classifiedas ordinary fill, and no construction machinery or other vehicle will pass over thepipe. Select fill complying with Table 3 is available.The following data are given:

External diameter of pipe, DDepth of trench to pipe invertSupport type

What class of pipe is required­(a) generally in the paddock; and(b) for a section which will pass under a concrete water tank if the uniform intensity

of load at the surface due to the full tank is 30 kN/m 2?

Calculation (a).

Depth of fill, H = 2.0 - 0.5 = 1.5 mWidth of trench, B = 0.53 + 0.6 = 1.13 m (> I.4D)Unit weight of fill = 20 kN/m3

Following the same procedure as for Example 1:From Figure 7, for HIB = 1.33 and Curve A, C t 1.13.Substituting in Equation 1-

Wg = 1.13 x 20 x 1.132

= 28.9 kN/m.From Figure 8, for HID = 1.5/0.5 3 and rsp = 1.0, C/c 1.65.

Substituting in Equation 2,Wg = 1.65 x 20 x 0.53 x 1.5

= 26.2 kN/m.Again adopting the lesser value and the bedding factor of 1.5 from Table 5, wehave:(i) from Clause 10.2, for reinforced pipe, the test cracking load given by­

Te ~ 26.211.5~ 17.5 kN/m; or

(ii) from Clause 10.3, for unreinforced pipe, the test load given by­

Ttl ~ 1.5 x 26.2/1.5 ~ 26.2 kN/m.

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17 AS 3725 Suppl-1989

t

Solution (a). From Table 4.2 of AS 1342, a 450 mm diameter Class S pipe wouldbe satisfactory in the open paddock.From Table 4.1 of AS 1342, the test load for a 450 mm diameter Class C(unreinforced) pipe is 22.0 kN/m, hence a 450 mm diameter Class C pipe would notbe satisfactory in this area.

Calculation (b). In accordance with Clause 6.4, the uniformly distributed dead loadof the tank is converted to an equivalent height of fill using Equation 5, i.e.-

He = 30/20 = 1.5 mand the height of fill, H, now becomes 1.5 + 1.5 = 3.0 m.Recalculating, HIB = 3.0/1.0 = 3.0, C l from Figure 7 is found to be 2.1, andEquation 1 gives-

Wg = 2.1 x 20 x 1.13 2

= 53.6 kN/m.Recalculating HID = 3.010.53 = 5.7, C/ e from Figure 8 is found to be1.67 (rsP = 1.0), and Equation 2 gives-Wg = 1.67 x 20 x 0.57 x 3.0 f

= 57.1 kN/m.Hence, the test loads from Clauses 10.2 and 10.3 are-

Tc ~ 53.6/1.5 ~ 35.8 kN/m for reinforced pipes, andTu ~ 1.5 x 56.211.5 ~ 56.2 kN/m for unreinforced pipes.

Solution (b). Referring to Tables 4.2 and 4.1 of AS 1342 for 450 rom diameter pipes,under the water tank a Class Z reinforced pipe would be satisfactory, but a Class Cunreinforced pipe would not be suitable.

A4 EXAMPLE 3.Problem. A size 600 mm concrete drainage pipe is to be laid in a trench which crossesunder a single lane country road designed for NAASRA Al4 vehicles. Thespecification requires the pipe support to be Type H2 and backfilled with SC materialcompacted to an in-situ unit weight of 20 kN/m3

• Given that the outside diameterof the pipe is 0.7 m and that no construction equipment will be allowed to pass overthe pipes, what class of pipe will be required if the depth from the road surface tothe pipe crown is 1.0 m, or alternatively 0.4 m?

Calculations.Alternative 1. H = 1.0 m: D = 0.7 m.

B = 0.7 + 0.6 = 1.3 m > I.4D.Hence HIB = 0.77.

(a) Working load due to fill.(i) From Figure 7, for HIB = 0.77 and Curve B, Ct = 0.69.

Substituting in Equation 1,Wg = 0.69 x 20 x 12

= 13.8 kN/m; or(ii) From Figure 8, for HID = 1/0.7 1.43 and rsp = 1.0, C/e 1.34.

Substituting in Equation 3,Wg = 1.34 x 20 x 0.7 x 1.0

= 18.8 kN/m.Taking the smaller of these values as the design working load,use Wg = 13.8 kN/m.

(b) Working load due to NAASRA vehicle load. Since His greater than 0.6 m, theintensity of the live load may be taken from Figure 11 (see Clause 6.5.2.3), whichgives q = 23.5 kN/m 2

•

From Clause 6.5.2.2 and the data in Commentary Clause C6.5.2.3, the base ofthe load prism has dimensions-

L2 = a + 1.45H = 0.2 + 1.45 x 1.0= 1.65 m in the direction of travel (> D)

L 1 = G + b + 1.45H = 1.8 + 0.5 + 1.45 x 1.0= 3.75 m transverse to the direction of travel.

Hence L c = 3.75 + (l.45 x 0.75 x 0.7)= 4.51 m.

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AS 3725 Suppl-1989 18

From Clause 6.5.2.4, substituting in Equation 7-

W - 23.5 x 3.75 x 0.7Q -

4.51

= 13.7 kN/m.

(c) Test load. From Table 5 (Clause 9.2.1.2), for support Type H2, the beddingfactor, F, is 2.0.

Substituting in Equation 8 (Clause 10.2),

Tc~ 13.8 + 13.7

2.0 1.5

~ 16.0 kN/m.

Solution. Referring to Table 4.2 of AS 1342, a 600 mm diameter Class S pipe willbe required.

Alternative 2. H = 0.4 m; D = 0.7 m; B = 1.3 m.

(a) Working load due to fill.

(i) From Figure 7, for HIB = 0.31 and Curve B, Cr = 0.30.

Substituting in Equation 1­

Wg = 0.30 x 20 x 1.02

= 6.0 kN/m; or

(ii) From Figure 8, for HID = 0.57 and rsp = 1.0, C/e = 1.12.

Substituting in Equation 2,

Wg = 1.12 x 20 x 0.7 x 0.4= 6.3 kN/m.

Taking the smaller of these values as the design working load, useWg = 6.0 kN/m.

(b) Working load due to NAASRA vehicle load. Since H is less than 0.6 m, Note 2to Clause 6.5.2.3 indicates that the load should be considered as acting directlyon the pipe. However, Commentary Clause C6.5.2.2 indicates that the usualdistribution is acceptable where 0.3 ~ H ~ 0.6 and that the length of pipeassumed to carry each wheel load is L e, as defined in Clause 6.5.2.4.

Referring to Figure 10 and using the AI4 data from Commentary Clause C6.5.2.3,

L 1 = 0.5 + 1.45 x 0.4= 1.08 m

L e = L, + (1.45 x 0.75D)= 1.08 + (1.45 x 0.75 x 0.7)= 1.84 m

L2 = 0.2 + 1.45 x 0.4= 0.78 > D.

From Equation 6, with a = 1.2 and Ep = 70 kN (single wheel),

q = __I_.2_x_7_0_ = 99.7 kN/m 2

1.08 x 0.78

From Equation 7,

W _ 99.7 x 1.08 x 0.7q -

1.84= 41.0 kN/m.

Substituting the above values for Wg and Wq in Equation 8,

Tc~ 6.0 + 41.0

2.0 1.5~ 30.3 kN/m.

Solution. Referring to Table 4.2 of AS 1342 for 600 mm diameter pipes, a Class Ypipe will be required.

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19 AS 3725 Suppl-1989

A5 EXAMPLE 4.Problem. A size 750 mm reinforced concrete pipe is required for the outlet to aretardation basin for a flood-mitigation scheme. Normal creek flow through the basinwill be contained in a concrete-lined channel whose invert is 350 mm below naturalground level. The outlet will pass through an embankment constructed from clayeysand to a depth of 5 m over the top of the pipe and the top water level will be 0.5 mbelow the top of the embankment.

If Type-HS2 support is specified, what class of drainage pipe will be required forthe outlet?Calculations. Assuming a minimum internal pipe diameter of 750 mm and a wallthickness of 50 mm, from the data we have-

,0.05

.' ...

h

HID .....•.. < •. •··.·.·.·····.·:i" ."-'-"'--.... : .

From the sketch above, it can be seen that there is positive projection where

h = 0.75 - 0.35 + 0.05= 0.45 m.

Projection ratio, P = hiD= 0.45/0.85= 0.53.

From Clause 6.3.5, f s = 1.0hence fsP = 0.53.

The working load due to fill in the embankment condition, for positive projection,is given by Equation 2, i.e.-

Wg = C'ewDH.

From Figure 8, for rsp = 0.53 and HID = 5.9, C'e 1.49.Substituting in Equation 2-

Wg = 1.49 x 18 x 0.85 x 5= 114.0 kN/m

From Table 5 (Clause 9.2.1.2), for Type-HS2 support, F = 2.5.

Check internal water pressure.Working pressure at level of spring line = (5.0 - 0.5 + 0.43) x 9.8

= 48.3 kPaFrom AS 1392, minimum test pressure (Tp) = 1.2 x 48.3

= 58 kPaSince this is less than 100 kPa, Equation 8 may be used.

Substituting in Equation 8 (no live load)-

Tc

) 114.0

2.5) 45.6 kN/m

Solution. Referring to Table 4.2 of AS 1342 for 750 mm diameter pipes, not lessthan a Class Y pipe would be required.

A6 EXAMPLE 5.Problem. A dual-lane highway designed for NAASRA loading crosses a gully onan embankment constructed of compacted clay having an in-situ unit weight of20 kN/m 3

• A size 1500 mm reinforced concrete drainage pipe is to be provided with

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AS 3725 Suppl-1989 20

Type-HS3 support through the bottom of the embankment, the top of which at thispoint is 15 m above the pipe crown. To minimize costs, it is intended to utilize induced­trench construction in laying the pipe. If the maximum height of excavation allowedin clay without using trench shoring is specified as 1.5 m, what class of pipe will berequired? .

Calculations.

(a) Working load due to jill. Assuming a pipe wall thickness of 85 mm.

D = 1.50 + 0.17= 1.67 m.

Taking the depth of the induced trench as the maximum allowed without shoring,we have from Figure 3(b) and the above-

H = 15 mh' = 1.5 mB = D = 1.7 m; HIB = 15/1.7 = 8.8

Negative projection ratio, p' = h' I D= 1.5/1.7= 0.88.

From Clause 6.3.5, for negative projection and earth foundation, rs = - 0.5.For the induced-trench condition, the working load due to fill is given byEquation 3 (Clause 6.3.4), the coefficient (C' n) being determined from Figure 9.

Referring to Figure -

9(a) for p' = 0.5; HIB = 8.8 and rs = -0.5; C'n = 0.69.

9(b) for p' = 1.0; HIB = 8.8 and rs = -0.5; C'o = 0.58.

Interpolating linearly for p' = 0.88, C' n = 0.61.

Substituting in Equation 3-

Wg = 0.61 x 20 x I.7 x 15= 311.1 kN/m.

(b) Working load due to live loads. Referring to Figure 11, it can be seen that forH = 15 m, the intensity of the working live-load would be less than 3 kN/m2

•

At this depth the ratio L [IL e would be close to 1.0, hence the working live load(Wq) from Equation 7 would be approximately 3 kN/m. This is negligible withrespect to the working dead load and hence can be safely omitted from thecalculation of an appropriate test load. (See Note 3 to Clause 6.5.2.3.)

(c) Test load. From Table 5 (Clause 9.2.1.2) for Type-HS3 support, the maximumbedding factor (F) is 4.0.

Substituting in Equation 8­

Tc~~4

~ 77.8 kN/m.

Solution. Referring to Table 4.2 of AS 1342 for 1500 mm diameter pipe, a Class Ypipe would be required.

As the construction of the 'induced trench' is of itself a reasonably expensive item,a reduction in the depth of the trench would be worthwhile investigating. For exampleif the depth (h ') was reduced to 0.85 m, the test load, (Tc) would increase to 88 kN/m,which would require a Class Z pipe. A cost analysis of these two alternatives wouldindicate which was the more cost-effective in terms of total construction costs.

A7 EXAMPLE 6.

Problem. A road embankment is to be constructed from sandy clay to cross a drycreek at a finished height of 15 m above the bed. The specification calls for twinsize 1050 mm concrete pipes to carry the estimated peak creek flow through theembankment and requires the pipes to be provided with Type-HS2 support with abed-zone thickness (X) of 150 mm.

If site investigations show that 0.5 m depth of silty material has to be removed fromthe creek bed to expose a satisfactory earth foundation, what class of concrete pipewill be required?

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21 AS 3725 Suppl-1989

I

Calculations. Assume a pipe wall thickness of 85 mm.

D = 1.05 + 0.17= 1.22 m.

The top of the pipes will project above the creek bed by a distance (h) where­

h = 1.22 + 0.15-0.5= 0.87 m.

The (positive) projection ratio (P) = hiD= 0.87/1.22= 0.71.

From Clause 6.3.5 the settlement ratio (r5) for positive projection and earth foundationis 1.0,

hence r5P = 0.71.

The height of fill (if) above the pipes is given by-

H 15.0 -0.8714.13m

hence HID = 14.13/1.2211.6.

(a) Working load due to fill. From Clause 6.3.6, the working load per pipe dueto fill is calculated from Equation 2, Le.-

Wg = C'e wDH

From Figure 8, for HID = 11.6 and rsP = 0.71, C'e = 1.58.Assuming a value of 18 kN/m3 for w (Commentary Clause C5)-

Wg = 1.58 x 18 x 1.22 x 14.13= 490.3 kN/m.

(b) Working load due to live loads. As indicated by Note 3 to Clause 6.5.2.3 andas shown in Example 5, live loads due to road vehicles can be neglected.

(c) Test load. From Table 3 (Clause 9.2.1.2), the bedding factor for GS2 beddingis 2.5.

Substituting in Equation 1-

Tc~ 490.3

2.5

~ 196.1 kN/m.

Solution. Referring to Table 4.2 of AS 1342 for 1050 mm nominal diameter pipe,it can be seen that this value is greater than the value given for Class Z pipes by afactor 196.1/84 = 2.33. Hence a special pipe will be required capable of sustaininga test cracking load of at least 202 kN/m (Class 2.4Z). Note that from Figure 17(Clause 9.2.3.1), the minimum depth of compacted material required above thebottom of the pipes for Type-HS2 support is 0.7D and from Table 5, the minimumdepth of the bed zone (X) is 100 mm.

Hence minimum total depth of compacted select fill = 0.7 x 1.22 + 0.10= 0.95 m above foundation

level

Since a non-standard pipe class is indicated, the use of Class Z pipes with an 'inducedtrench' should be investigated as a possible alternative (see Example 7).

AS EXAMPLE 7.P.roblem. A Railway Authority inten~s to construct a spur line requiring a 40 mhIgh sandy clay embankment at one pomt over a gully. The Authority has a numberof 2100 mm nominal internal diameter pipes with 220 mm thick walls which have

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AS J7lS Suppl-1989 22

been classified as Class 2Z and wi hes to use them to drain the embankment by asingle pipeline at thi point. Can this be done?Calculations. Assume that Type-HS3 bedding will be used with a bed zone thickne sof 150 mm (see Table 5).(a) Load capacity check.

(i) Loads due to fill:

D = 2.1 + 0.44= 2.54 m

h = 2.54 + 0.15= 2.69 m

p = hiD = 1.1.From Clause 6.3.5, rs = 1.0.Hence rsP = 1.1H = 40 - h = 37.3 m.Hence HID = 14.7.From Figure 8, C /e = 1.68.Substituting in Equation 2-Wg = 1.68 x 18 x 2.54 x 37.3

= 2865 kim.(ii) Railway live loads. From Figure 12, it can be seen that railway live loads

will be negligible at H = 37 m and hence can be neglected.(iii) Test load. For Type-HS3 support, the bedding factor is 4.0 (from Table 5,

Clause 9.2.1.2).Substituting in Equation 8­Te ~ 2865/4

~ 716.2 kNlmFrom Table 4.2 of AS 1342, the test cracking load for 2100 mm nominal sizeClass Z pipes is 140 kN/m. Hence for Class 2Z the test cracking load would be2 x 140 = 280 k 1m. As this is less than the required test cracking load, thepipes could not be used under straight embankment conditions.

(b) Induced-trench condition alternative. For this height of embankment (40 m), aninduced-trench condition is feasible and the question becomes one of determiningthe depth of induced trench (h ') required for the pipes to be satisfactory.From Equation 8, using the bedding factor of 4.04xTe =Wg

and from Equation 3 (Clause 6.3.4), for the induced-trench condition,Wg = C'n wBH.

Assuming B = D and substituting the known values­4 x f80 = C'o x 18 x 2.54 x 37.3Hence required value of C/o is given by-

c/o 4 x 280

18 x 2.54 x 37.3= 0.657.

From Table 1 (Clause 6.3.5), for the induced trench condition and earthfoundation, r s = -0.5 and since B = D, then HIB = 37.3/2.54 = 14.7.Referring to Figure 9 for C/o we find that for these values and(i) p' = 0.5; C' 0 = 0.68;(ii) p' = 1.0; C' 0 = 0.56; andby linear interpolation for C' 0 = 0.657, p' = 0.596.

Now p' = !!..:.­B

therefore h / = 2.54 x 0.596 = 1.51 mSolution. The pipes can be utilized if Type-HS3 support is u ed and an 'inducedtrench' 1.5 m deep by 2.6 m wide is constructed over them.

A9 EXAMPLE 8.Problem. A new size 1050 mm drainage line is to be put through an existing sandyclay embankment carrying a major highway. The Road Authority requires the pipeto be jacked through the embankment with the obvert of the pipe at 30 m below the

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23 A 3725 Suppl-1989

I

For jacked pipes the working dead load is given by

road surface. If the in-situ unit weight of the embankment material is given a18 k 1m3

, what clas of concrete pipe will be required?Calculations. Assume a wall thickness of 75 mm.

D = 1.05 + 0.15= 1.20 m.

(a) Dead load due (0 fil/.Equation 4-Wg = C,wB2 -2cC,B.Assuming that B = D = 1.20 m,then HIB = 30/1.2

= 25.From Figure 7, for HIB = 25 and Curve B for clayey and (w = 18 k 1m 3),

the value of C, i 3.2.

Assuming that the clay in the embankment ha been well compacted but thatjacking will affect this somewhat, a conservative value of 2 kPa can be chosenfrom Table 2 for the soil parameter (c). Substituting the values in Equation 4we have-

Wg = 3.2 X 18 x (1.2)2 - 2 x 2 x 3.2 x 1.2= 82.94 - 15.36= 67.6 kN/m.

(b) Road live load. From Figure 10 it can be seen that the live loads from road trafficcan be neglected.

(c) Test load. From Commentary Clause C6.3.6 and Clause 9.2.1.2, a beddingfactor is chosen conservatively as 2.Substituting the above values in Equation 8-

Tc~ 67.6

2

~ 33.8 kN/m.

Solution. Referring to Table 4.2 of AS 1342 for 1050 mm nominal size pipe, aClass X pipe would be satisfactory.

Joint check. Assume a 1000 kN jacking force.

Compressive stress on joint = 4 x P17r(Do2- D/), where Do and Di are

respectively the external and internal diameters of the joint.

4 x 1 X 106

7l" (12002- 10502

)

= 3.8 MPa.

From Commentary Clause C6.3.7, a jacking force of up to 3000 kN could be used.

A10 EXAMPLE 9.

Problem. A 750 mm nominal bore concrete irrigation line is to pa s through a sandyclay roadway embankment. The road i a dual lane highway designed for AASRAvehicle loads and where it crosses the pipeline its surface is 2;5 m above the pipe invert.The de ign specification calls for the pipe to withstand a shut-down head of 40.0 mplus a 25070 allowance for water hammer. The construction specification calls for thepipe to have a Type-HS2 support laid concurrently with the embankment construction,and compaction of the material around and over the line to be carried out by hand­held pneumatic tools. Field tests on the embankment material have shown that itcomplie with Table 4 grading but that the - 0.6 material does not comply withTable 3 grading limits. However, it can be compacted to an Ro of 90070 with a unitweight of 19 kN/m 3 and will therefore be used unmodified for the pipe supportmaterial. What class of pipe and test pressure is required for the ection of the linepassing through the embankment?

Calculation. Assume the pipe wall thickness is 75 mm. The construction specificationindicates positive projection in embankment conditions with h = D.

D = 0.75 + 0.15 = 0.90 m.H = 2.5 - (0.75 + 0.075) 1.68 m.p = hiD = 1.0.w = 19 kN/m 3

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AS 3725 Suppl-1989 24

(a) Working load due to fill. Clause 6.3.3 applies.From Clause 6.3.5, rs = 1.0,hence rsp = 1.0, and HID = 1.68/0.9 = 1.86.From Figure 8, C Ie = 1.46.Substituting in Equation 2-

Wq = 1.46 x 19 x 0.9 x 1.68= 41.9 kN/m.

(b) Working live load. The construction specification indicates that only theNAASRA vehicle loads apply. As the road is dual lane and H > 0.9 m, adjacentlane loads govern.From Clause 6.5.2.2.

L! = 2 x 1.8 + 1.2 + 0.5 + (1.45 x 1.68) = 7.74 m.L 2 = 0.2 + (1.45 x 1.68) = 2.64 m > D, hence S = D.Le = L, + (1.45 x 0.75 x 0.9) = 8.71 m.

From Figure 11 for dual lane and H = 1.68, q = 13.5 kN/m2•

Substituting in Equation 7-

13.5 x 7.74 x 0.9

8.7110.8 kN/m.

(c) Internal working pressure. From the design specification­Pw = 1.25 x 40 x 9.8

= 490 kPa.(d) Combined external load and internal pressure.

(i) Bedding factor for dead loads. From Table 5, the bedding factor for Type­HS2 support is 2.5. However, the supplied field information indicates thatthis must be reduced in accordance with Clause 9.3.2.

F = 2.5 x 0.85 = 2.13Hence a value of 2.0 will be adopted.

(ii) Test pressure. From Clause 10.4­1.2Pw ~ P t ~ 2.4PwFrom Figure C8 in Commentary Clause ClO.4, the maximum sustainabletest pressure for a size 750 mm pipe is 950 kPa, i.e. 1.9Pw •

Hence the practical range for Pt is 1.2Pw to 1.9Pw •

(iii) Combined loading.Assume Pt = 1.2Pw • Substituting in Equation 10-

Tcp ~ [41.9 + 1O.8J x [ 1.2Pw] 1/3

2.0 1.5 1.2Pw - Pw

~ 28.15 X 61/3

~ 51.2 kN/m

Solution. From Table 4.2 of AS 1342 for 750 mm nominal diameter pipe, a Class Zpipe would be suitable, the corresponding test pressure requirement being 588 kPa.Alternatively if PI is assumed to be 1.5Pw, Tcp reduces to 40.6 kN.m, which wouldrequire only a Class Y pipe but with a corresponding test pressure of 735 kPa.As both these solutions would satisfy the requirements of the Standards, the finalselection would have to be made on the basis of relative cost.

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25

APPENDIX B

DATA FOR DESCRIPTION, IDENTIFICATION ANDCLASSIFICATION OF SOILS BY THE UNIFIED SOIL

CLASSIFICATION SYSTEM

AS 3725 Suppl-1989

Bl GENERAL. This Appendix is a reproduction of Table Dl in Appendix D ofAS 1726-1981, SAA Site Investigation Code. It is included in this Supplement toassist users of AS 3725 to identify soils which will meet the definition of 'select fill'given in Clause 4 of the Standard and which are required to provide support to thepipe in accordance with Clause 9 of the Standard.The Plasticity Chart at the end of the Table is required to further distinguish theselect fill materials for HI bedding which do not need cement stabilization, as notedin Clause 9.2.2.2 of this Standard.It is recommended that AS 1726 be referred to, not only for selecting appropriatefill materials but also for the initial investigation of the ground along the pipelineroute, to establish the basic data essential for determining loads in accordanye withthis Standard.

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AS 3725 Suppl- 1989 26

TABLE Dl

UNIFIED SOIL CLASSIFICATION SYSTEM (METRICATED)DATA FOR DESCRIPTION IDE TIFICATION AND CLASSIFICATION OF SOILS

MAJOR DESCRIPTION

DIVISIONS GROUP !GRAPH(TYPICAL NAME OESCRI PTIVESYMBOL SYMBOL OATA

~ 0·0·0

'e E GW-0'0' Well graded grovels and grovel-sand mixtures, Give typical nome, Indicate approximate

III 0·0·0 '"...J <7'E '0- o· little or no fines percl'ntageos of sand and gravel; maximum SIze, .cw ~o o. 0.0 angularity; surface condition and hardness ~ e

E ~ ON 0 0:1-

of the coarse groins. local or geological name_ u

E IX Sc GP0 0 Poorly graded grovels and gravel-so nd m IX tures~ x 0

0 <:> 0 0 and other per tinent descriptive in forma t ion; ~.::<0 _0 0 0 little or no finesC 0= 0 0 symbols in parenth~sis

'" '"Ul 0 I--o'i~ o 0 U :J

..J.c

g~ V~(~>For undisturbed soils odd information on ~2 Ul

:;;E ~ GM Silty grovels, grovel-sand -s,lt mixtures ~ ~

6 0 s~ification, degree of compactness, cementation, :10 ..J'" E ...Jill C '" I/;~:~ "'> 6Ul .!!8 W...J o~ mOlstu~ conditions and drainage characteristics. .;'">- .c<7'

~a..c Ul

.. 0 <0 -'"0 a:'" "'~ GC 000Clayey grovels grovel-sand-cloy mixtures. EXAMPLE: 0-

UJ '" C <:> ~o

0'0

.c_ O00 a o 0 0 Silty Sand, gravelly, about 20'4 hard, angular '" 0

Z E= :I: '", UJo 0 grovel particles,10mm maximum siz~; rounded ; ~ Z

<{ t'~ ~-._. and sub-angular sand groins coorse to fIne; about

a:: "O~ SW .-.- Well graded sands and gravelly sands, little 15% non-plastic fines WIth low dry strength; '" E <{

~ >'0 '" <7' _.-. or no flOes E '" a::.o~ 0

~ E .-- well compacted and moist In place; light brown :1<7'~I EO

UJ *,0' Z (; E alluvial sand ISM) XC I< .... UJUl 0", VI 00 .... Poorly graded sands and gravelly sands, Illtle 0'"a:: l/l_ u SP ... E ~ Ul

<{ C _N . . . . or no fines .'" a::0 0 I--

a c ... ",a. <{

U £:~

~o ////!:'-o 0• .c '" '"'" 0- U

0 (5 "'", SM 'i'" Silty sand, sand-stlt mixtures. CoVI

C '" .// - E:I:

>- 2.!! E.::0 -~ [.X:·</ E '"z ",0 SC

0'"

< v./;: Clayey sands, sand-cloy mixtures. <DcVI 0 ~ 0

:I: .//- . '" >.b"=

r--- c0", I-;:"0

"'--E

o c

E ML -- Inorganic SiltS, very fine sands, rock flour, silty Give typical nome, ind icate degree and character E Q

0 -* - -- or clayey fine sands. of plasticity; amount and maximum size 01 00.<0 §fil

-- '" ;:UlC

coarse grains; colour in wet condition; odour if '" u Ul..J

I0>'"

60 ...Jc Inorgan.c cloys of low to medIum plostlcity, gravelly any; local or geologIcal no"", and other pertinent 0'" ..J£: 0 CL descnptlve Informot,onj symbols In

_"0 6"O..c cloys, sandy cloys, stlty cloys, leon cloysc_

Ul '" E 5: f-- parent hes i s. '" 0 Ul~ E ~ ~

0 -<0 !!'" . ... "'<7' 0UJ .no ...J '" Organic slits and organic stlty cloys of low For undIsturbed soil odd Information on structure, 0.0

UJOL .It-.¥ - ",'0Z "'0 -..!:!-~ plostlclty stratification, consist~ncy In undisturbed and - '" Z4: ~ c - - remoulded states, mOIsture and drainage 0<7'

a:: >.0 II IIconditions.

E...; <{~.c Inorganic 511 ts, mlcQceous or diatomaceous fine sands x ~ a::

~ "0- MH II J I o ~

~f >.'" _;I. or silts, elastIC silts. EXAMPLE ~ '"III II 0.- I

UJ .o~ efil Clayey Silt, brown; low plasllcity, small 0.0 UJZ DE

u: ~~ .:i c

"'percentage of fine sand; numerous vertical "'- Z0_ 0 COVI

1?= CH Inorganic cloys of hIgh plostlc,ty, fat cloys root-holes; firm and dry in place,fililMLl LLC E t:::0 :J '" - '".c cr~ ~ c- - 0 ~1.MLt "'"0

~...JE

OH 1.£I.!It Organic cloys of medium to high plasticity,o ~

00

~ I ~I.c

:1:

... ...Pt ll<. '" Peat muck and other highly organic soils.......

only tbe

2 to 60 m.m0.06 to 2 m.m< 0.06 m.m

of the soil and classifies

NOTES:1. The above table follows the original Unified Classification System (USBR Earth

Manual) and ASTM D 2487 except that it adopts the particle size limits given inAS 1289 and other standards, viz:

Gravel ....SandSilt and clay ....

The system excludes the boulder and cobble fractionsmaterial less than 60 mm in size.

2. As 60 mm, 2 mm and 0.06 mm sieve sizes are not normally used the percentages passingthese sizes can be obtained from a particle s;ze distribution curve determined from alaboratory test. Alternatively, the percentages passing may be estimated in the field.

3. For field identification procedures for fine-grained soils or fractions, see Paragraph D6.

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27 AS 3725 Suppl-1989

r-__--;::;;-;-;:::-=-::-::__---.:G:.;R;:A:..:V.::.EL::.:S::..:.:A:.cN=D.,:S:::A:..:N:;:D:;:S~c_=c=_-_._=_=:_:_===,.,_lGROUPGRADATIONS NATURE OF FINES DRY STRENGTH SYMBOL

LABORATORY CLASSIFICATIONFIELD IDENTIFICATION I0/:-121

~~S~:~~ C =~ C=~o06mm FRACTION u 0 I 0 C D,oDfl

NOTES

1. Identify fines bythe methodgiven for fine­grained sails.

2. BorderlineclaSSificationsoccur when thepercentage offines (fractionsmaller than0.06 mm size) isgreater than 5%and less than12%, Borderlineclassificationsrequire the useof dual symbolse.g. SP-SM

GW-GC

betweent and 3

bel ween1 and 3

,

>4

>6

Falls to complyWith above

Falls to complyWith above

Below'A'line orI p<4

Above 'A'line and

I p >7

0-5

0-5

O-S

0-5

12-SO

12-SO

GP

GWNone

Low to medium

"Clean" matenals Inot enoughfines to bind coarse grains)

None to very slow

WIde range In grOIn size

Predominantly one sizeor l ronge of 5lzes.

Medium to high

GOODo;:

~:EU

£;r--+-------+---------1--~--+--i2

EE POORfilc2

:::,~o"-§"-

GOOD Fines are non-plastic 11) None to medium GM r~ ~ to "Dirty" materials (excess f------------+------+----I ~-on FAIR of fines) U

~~ Fines are plast.c (1) Medium to l1igh GC gI» C ell IIIH ~t--+------------i>-------------+------r--S-W-j ~

~ Q; ~ GOOD WIde range In groin size £- E!' g ''Clean'' matenals Inot enough None _(; 2 t_-+---------___i fines to bind coarse grains) '0

£; POOR Predominately one size SP cE or range of sizes. g:lII"t---!-----------+-------------!--------+----I ~ IS I----+---+---.---~:0 "= on Below'A'on Fines are non-plastic I t I None to medi<.rn SM ~;; 12 -SO line or;; GOOO 20 le<4ClI to "Dirty" moterials (excess u ... I----+--'-"---+---+---~

}1 FAIR of fines) Fines are plastic I,) Medium to high SC .2 % 12-50 ~~~:c;&. E~ le>7Vi SILT ANO CLAY FRACTION E ... I---........;..I'--_I.-__...... I.- ..J

" o~E ~ Fraction smaller than 0·20mm AS sieve sIZe on §E E ORY STRENGTH OILATANCY TOUGHNESS '" c~ : I---...::.;.'-'-.::..:..:===--+-----'====---!----'-===='---+----I ~ ~ I-.-

B-e-Iow-'

c:: None to low QUick te slow None ML 8. 'A' linea '5:5 .8t-----------+----------+----------+----I~ e-::l E ~ Medium to high None to very slow Medium CL 2: .E Above"E - 0 0 'A' line

:~ E .':0 ':-go E ....'"a ~ Low to medium Slow Low OL ~ ~ Belowo "- 0 :; oil 'A' loneE:: t_----------+----------+----------+----I uRi--"-_"=0" uH § o;!. Below

Low to medium Slow to none Low to medium rrJ'0 ~ .g ~ 'A' line_!!! f------------+----------+----------+----t 0 0 -

~ High to very high None High CH ; ~ ,:.~~,g ~ ~-

• oil

OH::J Below'A' line-"~

,.~::·'-.J._~ _l L +--+--..J.~I--~

R~od"y Identl! led by colour. odour. spongy feel and generally by fibrous lex ture Pt· "Effervesceswith H202

'0

~_Q.)Q

XUJo~ 20

(::U;::Vl 10«~

CH IV",'i'-

;9./

/ VOHor

CL-ML /' OL MHorM,L

20 30 '0 '0 70

LIQUID LIMIT WL 1%1

PLASTICITY CHARTFOR CLASSIFICATION

OF FINE'GRAINEO SOILS

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A 3725 Suppl-1989 28

NOTES

STANDARDS AUSTRALIA

Standards Australia is an independent not-for-profit organization,established in 1922. It operates formally under a Royal Charter as theStandards Association of Australia and has recognition as the peakStandards body in Australia through a Memorandum of Understanding withthe Commonwealth Government. The essence of its operation is to bringtogether individuals and organizations committed to a common objective­to establish Australian Standards as national benchmarks for products andservices so as to enhance quality of life and industry efficiency.

AUSTRALIAN STANDARDS ,Australian Standards are prepared by committees made up of experts fromindustry, governments, user groups and other sectors. The requirements orrecommendations contained in published Standards are a consensus of theviews of representative interests and also take account of commentsreceived from other sources. They reflect latest scientific and industryexperience. Australian Standards are kept under continuous review afterpublication and are updated regularly to take account of changingtechnology.

INTERNATIONAL INVOLVEMENTStandards Australia has an important role internationally. It is responsiblefor ensuring that the Australian viewpoint is considered in the formulation ofInternational Standards and that latest international experience isincorporated in Australian Standards. This role is vital in assistingAustralian industry to compete in international markets. Standards Australiais the national member of the International Organization for Standardization(ISO) and the International Electrotechnical Commission (lEG).

MEMBERSHIP AND INFORMATIONA comprehensive range of services is provided to subscribing members ofStandards Australia. Up-to-date information on latest local and internationaldevelopments in standardization, priority access to publications, and creditfacilities are some of these services. Standards Australia's largeInformation Centres in Sydney and Melbourne also prOVide referenceaccess to Australian and international Standards as well as thoseapplicable in overseas markets.

Enquiries about subscribing membership and the work of StandardsAustralia are welcomed at the Head Office or any State office. A Catalogueof Australian Standards is also available at these offices.