1、Designation: F 449 02e1An American National StandardStandard Practice forSubsurface Installation of Corrugated Polyethylene Pipe forAgricultural Drainage or Water Table Control1This standard is issued under the fixed designation F 449; the number immediately following the designation indicates the y
2、ear oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTESection 4.5 was editorially corrected in November 2003.1.
3、Scope1.1 This practice is recommended for and limited to gravityflow subsurface drainage systems or water table control, butnot recommended for sanitary or storm sewer applications.Procedures are outlined to minimize pipe deflection or struc-tural damage during and after the installation process. Th
4、eseinstallation procedures are in accordance with “flexible con-duit” principles.1.2 This practice applies to all agricultural subsurface drain-age or water table control installations using Specification F405, F 667 or other plastic pipe.1.3 This standard does not purport to address all of thesafet
5、y concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1600 Terminology for Abbreviated
6、 Terms Relating toPlastics2D 2412 Test Method for Determination of External LoadingCharacteristics of Plastic Pipe by Parallel-Plate Loading3F 405 Specification for Corrugated Polyethylene (PE) Pipeand Fittings3F 412 Terminology Relating to Plastic Piping Systems3F 667 Specification for Large Diamet
7、er Corrugated Poly-ethylene Pipe and Fittings33. Terminology3.1 Definitions are in accordance with Terminology F 412and abbreviations are in accordance with Terminology D 1600,unless otherwise specified.3.2 backfillmaterials used to fill the trench followinginstallation of the pipe and bedding.3.3 b
8、eddingmaterial which provides stable bottom sup-port for the pipe including the trench bottom groove supportangle or select material placed around the pipe, and envelopeor filter materials where used during installation.3.4 blindingthe placement of soil, bedding material overand on the sides of the
9、pipe or envelope to ensure proper grade,alignment, support, and protection of pipe during backfillingand after installation.3.5 boot (also shield) the protecting apparatus linked tothe rear of the installation machine in a manner which allowsplacement of the pipe on the trench bottom, protection of
10、theworkman, or placement of envelope or filter material, or both.3.6 cradlea prefabricated rigid structure designed to pro-vide trench bottom support for the pipe when soil support isinadequate.3.7 envelopeporous material placed around the pipe toprovide bedding, improve the flow of ground water int
11、o thedrain, or function as a filter.3.8 filteran envelope of natural or synthetic materialsplaced completely around a drain to permit free water move-ment into the drain, provide stabilizing support at the soil-filterinterface, and restrict movement of silt and sand into the drain.3.9 gradethe slope
12、 of the pipe invert.3.10 groove support angle angle between the radii of thepipe at points of contact with the formed groove of undisturbedsoil or a cradle.3.11 mineral soilssoil containing (1) less than 30 %organic matter by weight provided the mineral fraction is 60 %or more clay, or (2) less than
13、 20 % organic matter by weightprovided the mineral fraction has no clay, or (3) less than aproportional content of organic matter between 20 and 30 % ifthe clay content of the mineral fraction is between 0 and 60 %.3.12 natural granular envelopean envelope of granularmaterial, usually highly permeab
14、le well-graded sand andgravel.3.13 organic soilsoil containing (1) 30 % or more organicmatter provided the mineral fraction is 60 % or more clay, or (2) 20 % or more organic matter provided the mineral fraction1This practice is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems an
15、d is the direct responsibility of Subcommittee F17.65 on LandDrainage.Current edition approved Sept. 10, 2002. Published November 2002. Originallypublished as F 449 76. Last previous edition F 449 97.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 08.04.1Copyright ASTM
16、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.has no clay, or (3) a proportional content of organic matterbetween 20 and 30 % if the clay content of mineral fraction isbetween 0 and 60 %. (It is a general rule that a soil is classedas an organic s
17、oil (histosol) either if more than one half ofupper 80 mm (32 in.) of soil is organic or if organic soilmaterial of any thickness rests on rock or on fragmentalmaterial having voids filled with organic material.)3.14 pipe stiffnessforce per unit length, per unit deflectionas defined in Test Method D
18、 2412.3.15 power feedermechanism that applies force to thepipe as it passes through the boot or shield to reduce stretchduring installation.3.16 pre-rippingthe practice of making a pass with theplow without installing pipe to locate rocks and to reduce draft.3.17 start holea trench sufficiently long
19、 and wide to allowworking room for placing the boot or shield, blade or cuttingmechanism on grade to start the trench and to install connec-tions or pipe.3.17.1 DiscussionStart holes are usually dug with a back-hoe with a flat-bottom trench.3.18 stretchthe increase in length of the pipe caused byten
20、sion forces during installation. It is expressed as a percentincrease of the length prior to installation. Stretch differs fromelongation in that elongation is a material test and stretch is aninstallation test.3.19 synthetic envelope an envelope made of syntheticgeotextiles, usually thin synthetic
21、fabrics or thicker fibrousmaterial, or both, often selected to function as a filter.3.20 trench depththe depth of the trench measured fromthe bottom of the pipe.3.21 trench widththe width of the trench measured at thetop of the pipe.3.22 Fig. 1 illustrates the terms bedding, vertical deflection,back
22、fill material, cover, groove support angle, horizontal de-flection, trench width, and trench depth.Fig. 2 illustrates various support grooves or trench bottomshapes.Fig. 3 illustrates envelope and filter.Fig. 4 illustrates rodent protection devices.Fig. 5 illustrates boot or shield.4. General Requir
23、ements4.1 BurialThe maximum and minimum burial depth areaffected by the following factors, groove support angle of thetrench bottom, bedding, blinding backfill soil density, envelopedensity, envelope placement, pipe stiffness, the live loadexpected, desired water table depth, and width of trench.4.1
24、.1 Minimum Depth:4.1.1.1 Mineral SoilsThe minimum recommended coverneeded to protect the pipe from crushing under live loads is 0.6m (2 ft). Granular bedding or special construction techniquesmay be used to reduce the cover. The time for consolidation ofbackfill may be a factor (see 8.1). The minimu
25、m cover mayhave limiting factors other than crushing such as clearance forsubsoiling and utility crossing.4.1.1.2 Organic SoilsSubsurface drains should be in-stalled in these soils only after initial subsidence has occurred.To produce initial subsidence open ditches should be con-structed in deep or
26、ganic soils to carry off free water, and thearea should be allowed to stand or be partially cultivated for aperiod of 3 to 5 years before installing pipe. The recommendedminimum cover for the pipe in organic soils is 0.7 m (2.5 ft).If water level controls are not provided in the drainage systemto ho
27、ld subsidence to a minimum, the depth of cover should beincreased to 0.9 m (3 ft).NOTE 1These minimum depths are recommended to prevent crushingof the pipe by normal agricultural vehicle loads. Other drainage factorssuch as those encountered with salinity control in arid irrigated lands mayrequire m
28、inimum depths of 1.8 m (6 ft).4.1.2 Maximum DepthThe maximum burial depth is in-fluenced by such factors as degree of compaction, type ofbedding, support from the trench bottom, trench width, size ofFIG. 1 Terminology for Installation of Plastic Drain PipeFIG. 2 Support GroovesF44902e12pipe, pipe st
29、iffness, weight of backfill, and live loads imposed.Without an engineering design, maximum buried depths shouldbe limited to those listed in Table 1. For installation at depthsgreater than those listed in Table 1, specifications of andengineering design should be followed.4.1.3 Trench WidthIncreasin
30、g the trench width increasesthe soil load on the pipe. Side clearances of more than 150 mm(6 in.) on each side should only be used with an engineeringdesign and special construction (see Table 1). Trench widthmust be at least 50 mm (2 in.) wider than the pipe on each sidefor plow installation and 75
31、 to 150 mm (3 to 6 in.) on each sidefor open trench installation to allow sufficient bedding tosupport the pipe. If fine material cannot be placed alongsideand over the pipe, a wider trench should be considered orspecial bedding material supplied.4.2 Design ItemsIt is particularly important that bli
32、nding,bedding, or envelope material be placed as the pipe is installed,to ensure uniform continuous support, so that the bedding,blinding, or envelope material can provide lateral restraintagainst pipe deflection as the backfill settles on the bedding,blinding, or envelope material.4.3 EnvelopesMust
33、 be designed to provide adequate sup-port for the pipe, improve the flow of ground water into thepipe, and in some installations, filter flow into the pipe.4.3.1 Natural Granular EnvelopesMinimum thickness of75 mm (3 in.) around the pipe.4.3.2 Synthetic EnvelopesBlinding or bedding is neededto suppo
34、rt and hold the envelope and pipe in place.4.4 FiltersAre required when ground water can developvelocities sufficient to move sand or silt, or both, into the drain.Filters must be able to restrict the movement of these particlesinto the pipe so that the hydraulic capacity of the pipe ismaintained.4.
35、4.1 Granular FiltersDesign of a graded sand and finegravel filter should match the gradation of the specific soilfollowing criteria developed by the Natural Resource Conser-vation Service, the U.S. Bureau of Reclamation, or the U.S.Army Corps of Engineers.4.4.2 Synthetic FiltersThin synthetic fabric
36、 material orgeotextiles may be used where bedding, soil, and hydraulicconditions permit. The openings in synthetic filters must becompatible with the soil that surrounds the drain to preventexcessive movement of soil that otherwise could plug the drainor filter (see 5.3).NOTE 2These filters must be
37、specified to be compatible with the soiltype that encompasses the conduit since protective filters can plug anddecrease the inflow capability. Where fiberglass filter material is used, itshall be manufactured from borosilicate-type glass and the manufacturershall certify that it is suitable for unde
38、rground use. The fibers should be ofvariable size, with some larger fibers intertwined in the mat in a randommanner.NOTE 3Vegetative filter material such as straw, hay, corn-cobs,woodchips, sawdust, and coconut fiber are not recommended for use withflexible conduits because such conduits depend on t
39、he development oflateral support and these soft materials may not provide the necessarylateral support.4.5 GradeShall be as specified in the plan or guide.Deviations greater than the following shall not be allowed.Vertical deviations of more than 0.1 ft (30.5 mm) in 10 ft (3.05m). Negative grade tha
40、t would fill the pipe more than 10 %.Due to the speed of installation with the plow, automatic gradecontrol is recommended. The pipe feeding system shall holdthe pipe in place in the bottom of the trench until secured by thebedding, blinding, or envelope material.4.6 Material RequirementsPipe and fi
41、ttings shall meet therequirements of the applicable ASTM standards referenced inSection 2 and Table 1.5. Significant Factors in Pipe/Soil Interactions5.1 ConnectionsIn start holes and adjacent open trenches,the pipe shall be aligned both vertically and horizontally,blinded and hand tamped along the
42、sides of the pipe to preventexcessive deflection.5.2 DeflectionThe deflection of corrugated plastic pipe isrelated to installation practice, bedding, groove support angle,blinding, gradation and density of soil, depth of installation,trench width in relation to pipe size, live loads imposed,stretch,
43、 and pipe stiffness of pipe. Maximum pipe deflectionshould be specified and not exceed 10 % of its nominaldiameter.5.3 FiltersSynthetic materials should never be used whenthe soil has a silt content greater than 40 %.5.4 Trench DepthSee 4.1.FIG. 3 Pipe Encased in Bedding for Support (left) and PipeE
44、ncased in Sand and Gravel Envelope Designed as Filter (right)F44902e135.5 Trench WidthThe width of the trench or blade belowthe top of the pipe should be adequate to allow placing pipe,reducers, and connectors in the bottom of the trench and shouldconform to 4.1.3.6. Construction6.1 AlignmentShould
45、be as smooth as possible with acurve radius larger than five times the pipe diameter.6.2 BackfillingPlace the backfill material so that displace-ment or deflection of the pipe will not occur. This is preferablyon an angle, so the material flows down the front slope. Avoidlarge stones, frozen materia
46、l, and dry clods that cause concen-trated direct loads on the pipe. The trench should be backfilledas soon as possible after blinding. When installing the pipe ona hot day back-filling should be delayed until pipe temperaturecools to the soil temperature (see 8.1).6.3 BeddingNecessary for the suppor
47、t and protection ofthe pipe. If adequate support is not provided by the soil andtrench bottom shape as shown in Fig. 2, envelopes or specialconstruction should be used.6.4 BlindingMaterial used for this process should notcontain any hard object larger than 38 mm (112 in.) in diameterand should cover
48、 the pipe to a depth of 150 mm (6 in.). See Fig.5 for possible boot and shield configuration.6.5 Bottom ShapeThe bottom should be one of the shapesshown in Fig. 2. The 90 “V” bottom of Fig. 2 works well onnominal sizes less than 200 mm (8 in.). The pipe is pressed intothe void, which reduces horizon
49、tal deflection in the completedFIG. 4 Suggested Methods of Providing Rodent Protection for Outlet PipesF44902e14installation. For pipe 200 mm (8 in.) or greater, the circular ortrapezoidal groove should be used. The curve of the circulargroove shall closely fit the outside of the pipe or there will beinsufficient support and deflection will be increased. Forflat-bottom trench, bedding must be used for support as in Fig.3.6.6 Couplers, Fittings, and CurvesFittings should beinstalled in accordance with instructions furnished by thema
