SANS 10120-3 LE-1982 Code of practice for use with standardized specifications for civil engineering construction and contract documents Part 3 Guidance for design Section LE Storm.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

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3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. SABS 0120 : Iart 3 section LE-1982 Stormwater drainage PART 3 : GUIDANCE FOR DESIGN SECTION LE Clause CONTENTS Page Number PRE-TENDER CONSIDERATIOl4S 1 .

4、 Investigations 1 . Previous records 1 Present and future land use 1 . Applicable economic norm 1 . Administration 1 General 1 . Availability of essential data 1 Documentatioi l Drawings to distinguish between plain and reinforced concrete pipes as designed 1 . Levels and grade lines on projects inv

5、olving multiple services 1 Width of excavation for pipe culverts 1 Cutting to length l Precast concrete box culverts 1 . Ends for corrugated metal culverts 2 DESIGN REQUIREMENTS 2 Design Criteria 2 . Introduction 2 . Objectives 2 . Minor system for frequent storms 2 . Major syst.em for infrequent st

6、orms 2 Control of the quality of run-off 2 . Integration with township layout 3 Design Details . 3 General 3 . Other references 3 Structural Design of Buried Pipelines 3 General 3 . Stress in AC pipe wall 3 . IIcvels and grade lines on projects involving multiple services 3 . Depth of cover 3 APPLIC

7、ABILLTY OF OTIIER SPECIFICATIOllS AND CODES 3 TEST PROCEDURES 3 General 3 . QUALITY CONTROL AND OTllEli CCNSIDEl?ATIUI.IS 3 General 3 First Revision November 1982 This section of the code supersedes / SADS 0120 : Part 3 : Section LE-1980 Approved by the COIJEiCIL OF TSlE SOUTil AFRICAN BUREAU OF STA

8、NUARLS bmb 01.20 : Part i Section LE-1982 Stormwater drainage SAUS 1200 LE : STORMWATER DRAINAGE NOTE: The clause number(s) given at the beginning or aftrr the heading of a clause is/are, unless otherwise stated, the number(s1 of the relevant clausc(s) of SABS 1200 LE. PHE-TENDER CONSIDERATlONS INVE

9、STIGATIONS Previous Records-. Ascertain what records exist of floods and storrowater flows over the area to be drained and analysc such records in the lighC of the considerations to be taken into account when designing the drainage system (see Clause 2 below). Prcsent and Future Isancl Use. Consult

10、the local authority that is to pay for and maintairi the drainage system, in regard to the planning, including long-term plannitlg, of land use. -icable kcorlomic=. Determine the relevant economic norm (see Clause 4 of Section 0) for the project before deciding whether to design in terms of 2.1.3 or

11、 2.1.4 below. AUMINISTRATION General. See Sections D, DH, and LB. Availability of Essential Data. Arrange matters in such a way that the requirements for stormwater - drains and sewer pipelines do not conflict. Ensure that detail drawings are available immediately after the contract has hen awarded

12、so that the contractor nay arrange a logical construction program for the stormwater drains and sewer pipelines that will not be disrupted (see 1.3.2 below), and so that he may free-drain his works at all times. (See also Subclause 2.1 of Section 1,s of Part 5 of the code.) DOCUMENTATION Drawings to

13、 Distirtyuish Between Plain and Reinforced Concrctc Pipes as Designed. Mark concrete plpes on the drawings clearly to show whether or not the pipes have been designed as reinforced concrete pipes. (See Subclause 3.2.1 of Section LE of Part 5 of the code.) Levels and Grade Lines on Projects Involving

14、 Multiple Services. Where stormwater drainage systems and sewer, water, and other services intersect on the plan layout of the project as a whole, exercise care in calculating invert levels arid grades for each intersecting service. Stormwater pipes are, generally, of larger diameter than other serv

15、ices and create particular problems that require an engineering solution. Decisions as to which service goes on top and which goes below are not the responsibility of the contractor. Anticipate each problem during the pre-tender stage and ensure that drawings showing levels and other such data do no

16、t contain potential coflicts where services intersect. Width of Excavation for Pile Culverts (Subclause 5.2.2). Certain local authorities prefer to specify as - follows: In the case of a siryle pipe culvert-, the width of excavation shall be equal to the nominal internal diameter of the pipe plus 0,

17、s m on each side. Where a pilc culvert consists of two or more pipes alongside each other, the minilnum spacing betweell adjacenl pipes shall, except where the backfilling is done with soilcretc., he 300 nun or one-half of the liominal outside diameter of the pipes, whichever is the greater, up to a

18、 maximuln of 900 mm. Where the backfilling between pipes of multiplc pipe culverts is done with soilcrete as specified ir PSLE 3.1 (see Subclause 3.2.5 of Section LE of Part 2 OF the code), the spacing between adjacent pipes shall be 225 mm or one-third of the nominal outside diamct.er of the pipes,

19、 whichever is the greater, up to a maximum of 500 mm. Cutting to Length ISubclause 5.2.1). Cutting pipes to length or skew is frequently necessary in the case -P- of skew culverts, or culverts with a cover of less than 0.5 m at the shoulder of a road or at the edge of an emlankment. Schedule suitabl

20、e items where cutting is likely to be ordered. Precast Concrutx Box Culverts (Subclause 3. l (c) ) - a) The proof load test as set out in SABS 986) is acceptable for decks in all circumstances but may not be adequate for inverts that will be subject to unevenly distributed loads. Where such loads ar

21、e expected, specify (or schedule) a hiqher class for the invert than is specified for the deck. b) Where the precasting of culverts by the contractor (riot being a manufacturer) on site or in his depot will be permitted, consider including a clause such as the following: PSLE 1.1 _Precast.iny of box

22、 culverts (Subclause 3.l(c). Design calculations shall be submitted to the Engineer for approval before precast culverts ore manufactured. Notwithstanding the requirements for cover of SANS 98611, the minimum cover to reinforccrrnent shall be 25 . All units shall, if so ordered, be subjected to the

23、applicable strength test given in SABS 9861qunand in addition, shall be capable of withstanding the appropriate proof load applied on any line parallcl to the longirudinal axis without showing any sign of shear failure or incipient shear failure. Each unit found to he defective shall be rejected. 1)

24、 Precast reinforced concretc culverts. SAW 0120 : Part 3 2 Section LE-1982 Stormwater drainage Ends for Corrugated Netal Culverts. As corugated metal culverts may be supplled wlth in2c.t and oui.lrt -p- ends finished by one of the following methorls, show on drawings how each end of such culverts is

25、 to be finished, unless the schedule clearly states for which end finish the contractor should pric.?: d) Where no concrc,te inlet and outlet structures ate required, lrilet and outlct unlts may bc hevellrxl to suit the skew angle of the culverts and the slope. L) Where concrete inlet and outlet str

26、uctures are required, the ends of the culvert units after, if necessary, bejny cut to the required plan skcw arigle, may be 1)rovlded with dnchor bolts of nomind1 length 0,5 m and nominal dldmetel l5 mm, projectng radlolly around thr- edge as shown on the rplrvat drawlngs, for securincl the metal cu

27、lverts to the concrete mlet and outlet structures. DESIGN KEQII IRRNENTS DESIGN CHlTCHlA Introductinn. Current. urban stormwater design practice in South Africa seoks to remove wate; from an -p- area as rapidly as possible, generally through a closed condult system. This has resulted in increased fr

28、eqnc:iies of downstream floodxng which have become more apparcnt ds conununities have expanded. A concept of stormwater design which has gained acceptance in the United States of America over the past ten years and is being actively promoted in South Africa, seeks as far as possible t.o detain and t

29、emporarily store rainfall where it falls, arid thus to mini.mize the rate of run-off. If this dcsign approach were tu be applied for a complete drainage basin, the cost of major downstream flood control facilities could be considcralrly reduced as could the costs of local stormwater systems. Thc mai

30、n advantage is better flood protection for the community. This coricept and details of the requirements for a design in whlch it is applied are set out fully in Par? I11 of Rational norms for engirecring servjccs for resident-ial townships2) and brlef ly n 2.1.2 - 2.1.6 below. Objectves. The main ob

31、jectives ol stormwater design are a) to prevent loss of liEe end siguficant dLunage to property durmg large storms which occuz relatively nfrequently, say once in fifty years; b) to mnirnszi. inconvenience during reldtlvely heavy storms with zecurrence jntervals of, sal, 1 in 2 ypars; ad c) to contr

32、ol the qualxty of urban rurr-oft entering natural water systems. These design objectives can best be implemented tlurinq the planniny of a township layout by ensuring that drainage system:; oxint for both the major and thc minor flooding evcnts. These systems may rot necessarily follow tlie sane rou

33、tes but shou1.d be so laid out as both to be interrelated and to optimize the times of concerri;ration. Minor Sxstem for Precjuent Storms. Thc minor system for frequent storms is very similar to a conventional .-M-. -“P piped stormwater system but is designed for a recurrence interval of only about

34、2 years, compared with 5 or 10 years for a conventional system presently being used. The reduced design recurrence interval permits greater use of street channels as drainage facilities, particularly in minor roads where traffic clensities are low. Altcrniltively, make greater use of overland flow a

35、nd open channel drasnaqe facilities, such as grassed channels where toad reserve widths ore sufficiclit, although such channels require regular maintenance. Also usc natural dr il I naqe channels wherever possible. Major System fcr Infrequrnt Strgyw:. The major system for infrequent run-oifs 1s requ

36、ired to accept - - -p rur,-off m excess of the cdpaclty of the minor system. Dessyn this system for an event with s recurrence intervd of b) tile exercise of control in areas subject to 5011 erosion, such as teriiporory construction sLtes, to prcvprrt silt-laden run-off from entering natindl wdtcr s

37、ystems; C) t:1e removal by filtration of pollutmts ar3slncj from physical, elriemical, and blologlcal processes; and d) the cletertioti of un-off to dlow settling processes to rernove sediments alid sediment-relai-ed pollrrtanis. -m- 2) In course oi prepdration Zor the Dcpartineirt of Community Deve

38、lopieit. SIIUS 01.20 : Part 3 Section LE-1982 Stormwater drainage Inteijration with Towiship Layout. Uesign urban stormwater systems so as to attenuate flood peaks, to minimize incoliveniericc caused by minor storms, and to reduce flood damage during larye storms. As these object.iver can be ncliicv

39、ed by the provisiori of separate storrnwdt.er systems for frequent and infrequent flooding events and by the provision of areas for temporary pondiny, integrate the planning of a stormwator drainage layout with the detailed planning of the layout of the township. DESIGN DETAILS General. Design tlre

40、detalls of a stormwdtcr drairiaqe system in accordance with the recommendations of Sections 4, 5, and 6 of Part I11 oi Rational norms for englrieerlng services for rcsldential townshlp22). Other Hefereiices. Consult the followitig references for additional guidance on the design of stormwater draj n

41、aqe : a) Sections 9 and 10 of uidelines on the 1lrln11jnr and design of township roads and stormwater drainage. published by the South Afrlcan Institution of Civil Engutcers in Johannesburg, August 1981; b) South African lrtstitution of Civil Engineers, Sixth Quinquennial Convention, Section on Urba

42、n Ilydrology and Stormwater Drainage : “Design philosophy for stormwater drainage“ by L.C. MILES (NBRI, CSIR), 1978. STRUCTURAL DESIGN OE BURIED PIPEI,INES General. Design stormwater pipelines in the nldrrner set out in Clause 2 of Section LB. Stress in AC pipe wall. Note that the permissible design

43、 stress in an AC pipe wall includes the - - requisite sdfety factor. Levels and Grade Lines on Projrxt-s Involviny Plultiple Services. See 1.3.2 above. Depth of Cover. When determining invert levels and the minimum cover Acquired, take cognizance of the strength of the pipeline and the load that wil

44、l be applied during the construction stages by the machinery likely to be used for earthwolks. Use as a guide the followirig tilble ol rninimun and rnaximum covers for a concrete plpe of known crushing strength (NOTE: Sirnllar data may Le calculated tor ?C pipes) : 3) COVER EOK SC TYPE, CLASS C CONC

45、RETE PIPES (SNiS 677 ), m p-p p Plain Nominal diameter, mm 450 600 7 50 Over 750 I beddiiq I bedding I casing I 0,40 0,30 0,20 0,50 0,30 0,20 Cover to be calculated for cacti pipeline APPLlCABlLITY OF 0TIlk;R SPECIFICATIONS AND CODES The requirements of SAIE 1200 and SAW l200 LE, and the recommendat

46、ions given in Clause 2 above take precedence over any reconmendatlons for pipe installation and design given in S-S 0102) or SABS 05e6). TEST PRCCEDUHES (Clause 7) GENERAL. See Suhclause 3.2.4 ui Sectiorl LE of Part 2 and Subclause 3.2.3 of Section LE of Part 5 of the code. QUALITY CONTROL AND OTIlE

47、K CGNSIDEMTlONS GENERAL. Apply the relevdnt reconmendations of SABS 157) to the design of stormwater drainage. 2) See p. 2. 3) Concrete non-pressure plpes. 4) Bedding (pipelines) 5) Structural clesign and installation of. precast concrete pipelines 6) Installation of sewerage oncl drainage non-pressure pipelines. 7) Quality management systcms. mbl Pt.