1、Designation: C 12 08Standard Practice forInstalling Vitrified Clay Pipe Lines1This standard is issued under the fixed designation C 12; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in parenthe
2、ses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers the proper methods of installingvitrified clay pipe
3、 lines in order to fully utilize the structuralproperties of such pipe.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This stand
4、ard does not purport to address all of thesafety 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 AS
5、TM Standards:2C 301 Test Methods for Vitrified Clay PipeC 425 Specification for Compression Joints for VitrifiedClay Pipe and FittingsC 700 Specification for Vitrified Clay Pipe, Extra Strength,Standard Strength, and PerforatedC 828 Test Method for Low-Pressure Air Test of VitrifiedClay Pipe LinesC
6、896 Terminology Relating to Clay ProductsC 1091 Test Method for Hydrostatic Infiltration Testing ofVitrified Clay Pipe LinesD 2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)3. Terminology3.1 GeneralTerminology C 896 can be used for clarifica-tio
7、n of terminology in this specification.DESIGN CONSIDERATIONS4. Supporting Strength4.1 The field supporting strength of vitrified clay pipe ismaterially affected by the methods of installation. The fieldsupporting strength of a pipe is defined as its capacity tosupport dead and live loads under actua
8、l field conditions. It isdependent upon two factors: (1) the inherent strength of thepipe and (2) the bedding of the pipe.4.2 The minimum bearing strength requirement in accor-dance with Specification C 700, as determined by the 3-edge-bearing test of Test Methods C 301, is a measure of theinherent
9、strength of the pipe.4.3 The tests used to measure bearing strength determinerelative pipe strengths but do not represent actual field condi-tions. Therefore, an adjustment called a load factor is intro-duced to convert minimum bearing strength to field supportingstrength. The magnitude of the load
10、factor depends on how thepipe is bedded. The relationship is:Field supporting strength 5 minimum bearing strength 3 load factor4.4 A factor of safety greater than 1.0 and less than or equalto 1.5 shall be applied to the field supporting strength tocalculate a safe supporting strength. The relationsh
11、ip is:Safe supporting strength 5Field supporting strengthFactor of safety5. External Loads5.1 The external loads on installed vitrified clay pipe are oftwo general types: (1) dead loads and (2) live loads.5.2 For pipes installed in trenches at a given depth, the deadload increases as the trench widt
12、h, measured at the top of thepipe, increases. Consequently, the trench width at the top of thepipe shall be kept as narrow as possible. Pipe failure may resultif the design trench width is exceeded. If the trench widthexceeds the design width, a higher class of bedding, strongerpipe, or both, must b
13、e investigated.5.3 Live loads that act at the ground surface are partiallytransmitted to the pipe. Live loads may be produced by wheelloading, construction equipment or by compactive effort.Compaction of embedment and backfill materials, beside andabove the sewer pipe, produces a temporary live load
14、 on the1This practice is under the jurisdiction of ASTM Committee C04 on VitrifiedClay Pipe and is the direct responsibility of Subcommittee C04.20 on Methods ofTest and Specifications.Current edition approved Nov. 1, 2008. Published November 2008. Originallyapproved in 1915. Last previous edition a
15、pproved in 2007 as C 12 07.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100
16、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.pipe. The magnitude of the live load from compactive effortvaries with soil type, degree of saturation, degree of compac-tion and depth of cover over the pipe. Care must be used inselection of compaction methods so that
17、 the combined deadload and live load does not exceed the field supporting strengthof the pipe, or cause a change in its line or grade.NOTE 1For generally accepted criteria and methods for determiningloads and supporting strengths, see Gravity Sanitary Sewer Design andConstruction, Water Pollution Co
18、ntrol Federation Manual of Practice No.FD-5, American Society of Civil EngineersManuals and Report onEngineering PracticeNo. 60.36. Bedding and Encasement6.1 Classes of bedding and encasements for pipe in trenchesare defined herein. The load factors indicated are for conver-sion of minimum bearing s
19、trength to field supporting strength.6.2 Class D (Fig. 2)The pipe shall be placed on a firm andunyielding trench bottom with bell holes provided (Fig. 9). Theinitial backfill shall be of selected material (Note 2).6.2.1 The load factor for Class D bedding is 1.1.NOTE 2Selected material is finely div
20、ided material free of debris,organic material, and large stones.6.3 Class C (Fig. 3)The pipe shall be bedded in cleancoarse-grained gravels and sands as defined in Practice D 2487,Table 1, (types SW, SP, GW, GP) (Note 4). Angular, non-consolidating bedding material not subject to migration may bespe
21、cified (as in Note 3). The bedding shall have a minimumthickness beneath the pipe of 4 in. (100 mm) or one eighth ofthe outside diameter of the pipe, whichever is greater, and shallextend up the haunches of the pipe one sixth of the outsidediameter of the pipe. The initial backfill shall be of selec
22、tedmaterial (Note 2).6.3.1 The load factor for Class C bedding is 1.5.NOTE 3Suitable material is well-graded34 to14 in. (19 to 6.4 mm)crushed stone, having a minimum of one fractured face, or other angular,non-consolidating bedding material not subject to migration. Well-gradedangular, non-consolida
23、ting bedding materials are more stable thanrounded bedding materials of equal gradation. Material shall be shovel-sliced so the material fills and supports the haunch area and encases thepipe to the limits shown in the trench diagrams (Figs. 3-6 and Fig. 8).NOTE 4Sand is suitable as a bedding materi
24、al in a total sandenvironment but may be unsuitable where high and rapidly changingwater tables are present in the pipe zone. It may also be undesirable forbedding, or haunching in a trench cut by blasting or in trenches throughclay type soil. Regardless of the trench condition or bedding class, the
25、maximum load factor for sand bedding is 1.5.6.4 Class B (Fig. 4)The pipe shall be bedded in suitablematerial (Note 3). The bedding shall have a minimum thick-ness beneath the pipe of 4 in. (100 mm) or one eighth of theoutside diameter of the pipe, whichever is greater, and shallextend up the haunche
26、s of the pipe to the springline. The initialbackfill shall be of selected material (Note 2).6.4.1 The load factor for Class B bedding is 1.9.6.5 Crushed Stone Encasement (Fig. 5)There are specificsites where crushed stone encasement may be desirable. Thecrushed stone shall extend to the specified tr
27、ench width andshall have a minimum thickness beneath the pipe of 4 in. (100mm) or one eighth of the outside diameter of the pipe,whichever is greater, and shall extend upward to a horizontalplane at the top of the pipe barrel (see Note 5). Encasementshall consist of well-graded34 to14 in. (19 to 6.4
28、 mm) crushedstone or other non-consolidating bedding material not subjectto migration. Material shall be carefully placed into the pipehaunches (Note 3). The initial backfill shall be of selectedmaterial (Note 2).3Available from American Society of Civil Engineers, 1801 Alexander Bell Dr.,Reston, VA
29、 20191.FIG. 1 TerminologyFIG. 2 Class DC12082NOTE 5Sufficient crushed stone or other suitable material (Note 3)shall be placed so that the bedding extends to a horizontal plane at the topof the pipe barrel following removal of any trench sheeting or boxes.6.5.1 The load factor for crushed stone enca
30、sement is 2.2.6.6 Controlled Low Strength Material (Fig. 6)Controlledlow strength material has been shown to be an economicalternative to compacted bedding material. It assists in utilizingthe inherent strength of the pipe, completely filling the hauncharea, and reducing the trench load on the pipe.
31、6.6.1 The pipe shall be bedded on crushed stone or othersuitable material (Note 3 and Note 4). The bedding shall havea minimum thickness beneath the pipe of 4 in. (100 mm) or oneeighth of the outside diameter of the pipe, whichever is greater.Controlled low strength material shall be directed to the
32、 top ofthe pipe to flow down on both sides to prevent misalignment.Fill to the top of the pipe. The initial backfill may be placedwhen the pour is capable of supporting the backfill materialwithout intermixing.FIG. 3 Class CFIG. 4 Class BFIG. 5 Crushed Stone EncasementC12083NOTE 6Attention is direct
33、ed to terminology and material references.See American Concrete Institute Report: ACI 229R-94 Controlled LowStrength Materials (CLSM).46.6.2 The load factor for controlled low strength material is2.8.6.7 Class AThis class of bedding can be achieved witheither of two construction methods.6.7.1 Concre
34、te Cradle (Fig. 7)The pipe shall be bedded ina monolithic cradle of reinforced concrete having a thicknessunder the barrel of at least 6 in. (150 mm) or one fourth of theoutside diameter of the pipe, whichever is greater, and extend-ing up the haunches to a height of at least one half the outsidedia
35、meter of the pipe. The cradle width shall be at least equal tothe outside diameter of the pipe plus 4 in. (100 mm) on eachside or one and one fourth times the outside diameter of the4Available from American Concrete Institute, P.O. Box 9094, Farmington Hills,MI 48333.NOTE 1This type of construction
36、requires the fill to extend from the pipe to the trench wall, not to extend above the top of the pipe or below thebottom of the pipe. Where native soils are expansive, further investigation may be necessary.FIG. 6 Controlled Low Strength Material (CLSM)NOTE 1Minimum width of concrete cradle: Bc+ 8 i
37、n. (205 mm) or 1-14 Bc.NOTE 2p is the ratio of the area of steel to the area of concrete. (It is recommended that wire mesh reinforcement or uniformly distributed smalldiameter rebar be used in all concrete design.)FIG. 7 Concrete CradleC12084pipe, whichever is greater. If the trench width is greate
38、r thaneither of these dimensions, concrete may be placed to fulltrench width. Suitable material shall extend upward to ahorizontal plane at the top of the pipe barrel. The initial backfillshall be selected material.6.7.1.1 The load factor for Class A concrete cradle beddingis 3.4 for reinforced conc
39、rete with p = 0.4 %, where p is thepercentage of the area of transverse steel to the area of concreteat the bottom of the pipe barrel as shown in Fig. 7.6.7.2 Concrete Arch (Fig. 8)The pipe shall be bedded insuitable material (Note 3). The bedding shall have a minimumthickness beneath the pipe of 4
40、in. (100 mm) or one eighth ofthe outside diameter of the pipe, whichever is greater, and shallextend up the haunches of the pipe to the springline. The tophalf of the pipe shall be covered with monolithic reinforcedconcrete arch with a minimum thickness from the top of thepipe barrel, of 6 in. (150
41、mm) or one fourth of the nominaldiameter of the pipe, whichever is greater. The width of thearch shall be at least equal to the outside diameter of the pipeplus 4 in. (100 mm) on each side, or one and one fourth timesthe outside diameter, whichever is greater. If the trench widthis greater than eith
42、er of these dimensions, concrete may beplaced to full trench width.6.7.2.1 The load factor for Class A concrete arch bedding is3.4 for reinforced concrete with p = 0.4 %, and up to 4.8 forreinforced concrete with p = 1.0 %, where p is the percentageof the area of transverse steel to the area of conc
43、rete above thetop of the pipe barrel as shown in Fig. 8.6.8 Concrete Encasement:6.8.1 There are specific sites where concrete encasementmay be desirable. Concrete encasement shall completely sur-round the pipe and shall have a minimum thickness, at anypoint, of one fourth of the outside diameter of
44、the pipe or 4 in.(100 mm), whichever is greater.6.8.2 The encasement shall be designed by the engineer tosuit the specific use.CONSTRUCTION TECHNIQUES7. Trench Excavation7.1 Trenches shall be excavated to a width that will provideadequate working space, but not more than the maximumdesign width. Tre
45、nch walls shall not be undercut.7.2 The trench walls can be sloped to reduce trench wallfailure. This sloping will not increase the load on the pipeNOTE 1Minimum width of concrete arch: Bc+ 8 in. (205 mm) or 114 Bc.NOTE 2p is the ratio of the area of steel to the area of concrete. (It is recommended
46、 that wire mesh reinforcement or uniformly distributed smalldiameter rebar be used in all concrete design.)FIG. 8 Concrete ArchFIG. 9 Uniform Pipe SupportC12085provided the measured trench width at top of pipe does notexceed the design trench width.7.3 Trenches, other than for Class D bedding, shall
47、 beexcavated to provide space for the pipe bedding.7.4 Sheet, shore, and brace trenches, as necessary, to pre-vent caving or sliding of trench walls, to provide protection forworkmen and the pipe, and to protect adjacent structures andfacilities.7.5 Sheeting shall not be removed below the top of the
48、 pipeif the resulting slope of native soil increases the trench width tosuch an extent that the load on the pipe exceeds the safe fieldsupporting strength of the pipe and bedding system.7.6 When a movable box is used in place of sheeting orshoring, secure the installed pipe to prevent it from moving
49、when the box is moved.7.7 Maintain the water level in the trench to an elevationbelow the bell of the pipe being laid. Exercise caution whenterminating the dewatering procedure to avoid disturbing thepipe installation.NOTE 7The purpose of controlling the water in the trench is tomaintain the lubricant on the joint surfaces, the integrity of the bell hole,and the ability to visually observe the cleanliness of the joint surfaces.8. Trench Foundation8.1 The trench foundation is the area below the pipe andbedding which supports the pipe bedding structure.8
