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POLYETHYLENE (PE) SPIRALLY ENWOUND STRUCTURE-WALL PIPE TYPE B/C

ENGINEERINGTECHNICALMANUAL

ABOUT LESSO GROUP

Establishdin986,LESSO(StockCode:228.HK)isagloballaderinomefurishingsandbildingmaterials.eGoup’sbusine portfoliospansstngingatelsdngotaroteplce andothers.Itersidngeofproductschsesotooambgdiayareitegainateeal doorsandwdfokdartsaodsaterpurifiesateroingateralsdantsfireghtit valves,bltaoaid LESSO’s sales revenue reached over USD 4.38 billion.

Sinceimplementingastrategofglobaizationndexpandingitsglobalpresence,LESSOasevoledintoasophsticatedmuiaialIt boastsoretnaedouctiosodidodengiustralndosrsiarthcao America,Euroricaasbtiditodctdftmeidceit its continuously improved strategic layout in a timely and efficient way.

LESSOhasfoundedits&Denterwihorethanoientiesearersatioalycredideterprisetechotedt post-doctoralworkstationstosupportitsinovatioandtechicaldevelopmentTeGroupastakenaladingolentherevisioofoer0 interationalandhineseindustrystandards.LESSownsover30patents(someofthemarepending)，andprovideso varetiesofproductsmakingitoneofthemostcompreensiemanufacturersinthepingindustryItsproductsareutizedglobalin diferentareasudingodecoatioistructionicialaterslyrainagergyanagementwrd telecommunications,gassupply,fire-fighting,environmentalprotection,agriculture,oceanicaquaculture,etc.

Truetoitsideaof“EvisiongteettingteFuture”ESOmaisomittedtoeatingttrlivngeviotad advocatinitsiu insustaining healthyand beautiful space so that global residents could enjoyacomfortable life.

CohesionandDrivers for Progress

JOINHANDS,FORGEAHEAD

ChinaLessoGroupHoldingsLimited(StockName:ChinaLesso,StockCode:02128.HK)isalargeindusrialgroupofhomefuisings andbuildingmaterialsinChina.ChinaLesso’sbusinessportfoiospansplasticpipingbuildingmaterialsandhomefurishings， environmental protection,new energy,supply-chain service platforms and others.

Contents

POLYETHYLENE(PE)SPIRALLYENWOUND STRUCTURE-WALLPIPETYPEB/C ENGINEERINGTECHNICALMANUAL

Preface 01
I. Product Structure 01
Il.Krah Pipe Series 02
1.PE Spirally Enwound Structure-wall Pipe Type B 02-03
2.PE Spirally Enwound Structure-wall Pipe Type B(D) (Grooved)... 04
3.PE Spirally Enwound Structure-wall Pipe PE Type C(T) (Flexible) 05
4.PE Spirally Enwound Structure-wall Pipe Type C 06
Ill. Physical and Mechanical Indicators 07
IV. Product Applications 07
V. Supporting Fittings 08
Vl. Product Connection Methods 08
1．Electrofusion Connection 08
2．Gasket Ring Connection. 09
VlI. Design 10-17
VIlll Construction 18-20
IX. Inspection 21

LESSO

Preface

LESSO polyethylene (PE)spirallyenwoundstructure-wallpipetypeB/Cseriesisanewtypeofprofiledstructure-wallpingproducts manufacturedthroughahot-statespiralwindingmoldingprocess.Thesepipesaremadefromhigh-densitypolyethylene (HDPE)resinathe primaraterlittatutdeldf circular hollow spiral ribs,classifying themas flexible pipes.

ThepipeseriesismanufacturedincompliancewiththenatioalsandardofthPolyetyleneStructureallPpingSystemsforUnderground Usage-Part2ltyeSrallwoundtructurallpes(B/4)anditsstructioadceptaneu follow the Technical Specification for Buried PEPipeline of Sewer Engineering (CECS164:2004).

LESSOPEspirallywoundstructure-wallpesareenvironmentalfiendyandsafe.Theyboastnumerousadvantages,includingiht weightstrongreuaapacitdjalityoceifosaeitft installationAspreferredpipesforburiedsewageanddrainagesystems,teyreidelyusedinfeldssuchasmunicipalwateupplnd drainage,largaleaterseacyectsttrodustrltalotectiot powerengineeing.Theyalsoserveasanidealreplacementfortraditionaldrainageandsewagepipessuchasreinforcedconcretepipes and cast iron pipes.

I. Product Structure

Spiralyenwoundstructurewallpeisatypeofspecial-structuredwallpipedesignedwithighresistancetoextealprsreItis manufacturedusingHDPEresinastheprimaryawmaterialthroughtheotstatespiralwindingmoldingprocesswithpolypropylne(P) single-wal corrugatedpipesasthesupportstructure.Theproductlineiscategorizedintofourseries:PR,OP,SQ,andVW:

ThePRadOPseriesaremainlyusedasburieddrainagepipes;theSQseriesisprimarilydesignedformanufacturingcontainersor inspectinchambrs;triesisinlteddfoteeodipfitifdcodaryroessingEduc thePRseriesin the greatest quantities.

Il. Pipe Series

LESOspialodturellifndbsinsl methodsicludeelectrofusionconnectionoublegasketringconnectionandsinglegsketringonnection.Thepipejntsanbe configuredinscketandspigottype,doublesockettypeodoublspigtpe,rovidingstrongdaptabittoariospoject requirements.lexiblespirallenwoundstructurewallpipesfeatureaninjection-moldedspigottructurendtheijintscanbediectly connected to our inspection chambers,ensuring good adaptability.

LESSO

1.PE Spirally Enwound Structure-wall Pipe Type B

1.1 Connection Method: Electrofusion Connection

1.2 Product Strengths

●High-quality weld seams are produced due to hot-state spiral winding with steel molds;
* Socket-and-spigot electrofusion connection guarantees good connection quality and 100 % leak-proof performance;
* High-strengthjintslowfrulieppetoeddtogetndtentetiresmblypieisoweredintottrnhving time and labor;
●Acomplete rangeof systemaccessories isavailable,including diferent supporting fitingsand inspectionchambers;
* Rawmaterialseetnatioalenvironmentalprotectioeqirements.incethepipeproductioprocssisonpollting,thepiefuly recyclable,green,and environmentally friendly;
EcelentdraageperformaneTsmothiepipealinizefrctioablingfastflowvelocitndgreaterdischargcit;
* Thepipes offer good corosion resistance andaging resistance,ensuringalong servicelife exceeding 50 years;
* Thegoodflexibilityofthepipesimproves theearthquakeresistanceand disastermitigationcapacityofpublicfacilities;
* Computer-basedstructuraldesign,electionndstrengthcalibrationprovidecustomerswithengineeringsolutionsandptimalprouct selection both quickly and accurately.

1.3 Product Specifications:

1.The pipes are manufactured in accordance with the GB/T 19472.2-2017 standard for structure-wall pipe Type B,except for those with a ring stiffness of SN10,which are produced according to our enterprise standard - Polyethylene (PE) Spirally Enwound Structure-wall Pipes for Buried Sewage and Drainage Systems.
2.The company specializes in products with ring stiffness grades of SN4, SN6.3, SN8,SN10,and SN12.5. Products with SN16 and above grades can be customized according to requirements;
3.The pipe color is generally black,but can be customized as agreed between the supplier and the purchaser.
4.The pipe length is generally 6m,or as agreed between the supplier and the purchaser.

LESSO

2.PE Spirally Enwound Structure-wall Pipe Type B(D) (Grooved)

2.1 Connection Method: Double Gasket Ring Connection

2.2 Product Strengths:

* The pipesareconnectedthrough double gasket ring,withoutstandingsealing performance,alowing for instalation in water-logged environments.
* Thedoublegasketringconnectionensuresthelongservicelifeofpipejints,eliableconnectionandeficienton-siteoction and operation.
* Thepipesareformedbyotstatespiralwindingdeliveringhighweldseamstrength,minimaliteralstre,smoothinnersufaces and a low fluid resistance coefficient.
←High ring stiffness: With a maximum value of up to 2 0 \mathsf { k N / m } ^ { 2 } ,the pipes offer good compatibility with a wide range of project requirements.

LESSO

2.3 Product Specifications:

1.The pipes are manufactured in compliance with the GB/T 19472.1- 2017 standard for structure-wall pipe Type B,except for those with a ring stiffness grade SN10,which are produced based on our enterprise standard -- Polyethylene (PE) Spirally Enwound Structure-wall Pipes for Buried Sewage and Drainage Systems.
2.The company specializes in products with ring stiffness grades of Sn4, SN6.3,SN8,SN10,and SN12.5. Products with SN16 and above grades can be customized according to requirements;
3.The pipe color is generally black,but can be customized asagreed betweenthe supplier and the purchaser.
4.The pipe length is generally 6m,or as agreed between the supplier and the purchaser.

3.PE Spirally Enwound Structure-wall Pipe Type C(T) (Flexible)

3.1Connection Method:Double Gasket Ring Connection

3.2 Product Strengths:

* Thesocktandsigtaefdbctiooingforentistalatiodnectoabingietndonetctio withour injection-molded inspection chambers.
* Thepipesfeatureasocket-and-spigotdoublegasketringconnection,oferingoutstandingsealingperformance.Both endscanbe customized into socket-and-spigot type or double spigot type.
* Thegasketringonnectionreqiesnoweldingequipmentofeingighinstalltionefiencyndlowconstructionostsdcanbe carried out in water-logged environments.
* Withawidediameterrange,tepipesareavailableinmutipleringstifessgrades (withhighstifessvalues)andareadaptableto differentengineeringrequirements.

LESSO

3.3Product Specifications:

1.The company specializes in products with ring stiffness grades of SN4,SN6.3,SN8,SN10,and SN12.5.
2.Thepipecolorisgenerallyblack,andthepipelengthisgeneraly6m,orasagreedbetweenthesuplierandthepurcaser.
3.Please note thatthe molds for products marked witha“★”in the specifications are stillunder development.

4.PE Spirally Enwound Structure-wall Pipe Type C

4.1 Connection Method:Gasket Ring Connection

4.2 Product Strengths:

* Hot-statecontinuous spiral winding molding ensures high quality of weld seams and good production efficiency.
* Socket and spigot are injection-molded and fusion-welded to the pipe body,ensuring a good 100 % leak-free connection;the socketand-spigot gasket ring connection enables fast installation with no leakage.
* The pipes are equipped with complete systemaccessories,including various supporting fitings and inspection chambers.
* Rawmaterialsmeetnationalenvironmentalprotectionrequirements.incetheproductionprocesisnon-polltingthepipearefuly recyclable, green,and environmentally friendly.
* Excelentdrainageperformance:Tsmoothinnrpipewallsinimizefrictionnablingfastfowvelocitandgeaterdishargeapacity
\bullet Thepipesoffergodcorrosionandagingresistanceesuringalongservcelifeexceeding50years.Thegoodfexibityofthepipes improves the earthquake resistance and disaster reduction capacity of public facilities.
Computer-bsdructuralsin,electiondtrengthiatioproidestomersitgieigsutioadtialuct selection quickly and accurately.

LESSO

4.3Product Specifications:

1.Thecompanyspecializesin products with ringstiffess gradesofSN4and SN8.Othergradescanbecustomizedaccording
torequirements.
2.Thepipecolorisgenerallyblack,andthepipe lengthisgeneraly9m,orasagreedbetweenthesupplierandthepurchaser.
3.Please note thatthe molds for products marked witha“★”in the specifications are stillunder development.
4. Detailed product specifications and connection methods are shown in the follwing table:

Ill. Physical and Mechanical Indicators

LESSO

IV. Product Applications

(1) Municipal Water Supply and Drainage: PE spirally enwound structure-wall pipe Type B (electrofusion) can withstand an internal pressure of up to 1 2 {kg } / {cm } ^ { 2 } making it an ideal replacement for existing cast iron drainage pipesand cement pipes in cities.

(2) Large-scale Water Conservancy Projects: Long-distance water conveyance, farmland irrigation,and sediment extraction in reservoir areas.
(3)Petroleum Industry:Oil and gas transmission pipelines.
(4) Coal Industry:Coal transportation projects and various ventilation systems.
(5) Chemical Engineering: Chemical containers and transmission pipelines for corrosive fluids.
(6) Environmental Protection Engineering: Deep-sea sewage discharge,sewage treatment,sewage discharge from garbage dumps,and toxic fluid discharge pipelines.
(7)Power Engineering:Circulatingwaterpipelines.
(8)Pipe laying in corrosive environments.
(9)Water culvertsand pedestrian underpasses beneath highwaysand railways with large traffic loads.
(10)Others:Fluid transmission in deserts,swamps,and lake areas,vertical or horizontal storage tanks, etc.

V. Supporting Fittings

Thesupportingfitingscanbeprovidedwithsuitableinjection-moldedinspectionchambersaccording tothespecificrequirements of customers.

LESSO

1．Electrofusion Connection

Installation Steps

1.Preparethetoolsforconnection.
2.Checkwhetherthesocketandspigotofthepipeare damagedandwhethertheheatingwireisintact.
3.Cleanany impuritiesonthe surfaceofthe electrofusionsocket andspigottoensure the connectionsurfaceiscleanand dry.
4. Insertthe spigot end of the pipe into the electrofusion socket, fixitwithasteelbucklestrap,and tighten itwithclamps.

T CDD

6.Cooling: After the electrofusion welding is completed,the power supply will be cut offautomatically. Cool it naturally,and water orair cooling is not permitted.The cooling time shall be more than 20 minutes in summer and more than 15 minutes in winter.

5.Electrofusion Welding:Selectappropriateelectrofusion parameters for weldingaccording to the parameter table on the electrofusion welding machine. <br>7.After cooling is complete,remove the steel buckle strap,and check the electrofusion welding condition.

2. Gasket Ring Connection

Installation Steps for Socket-and-Spigot Gasket Ring Connection

1.Prepare the tools for connection.
2.Check whether the socket and spigot of the pipe are damaged.

LESSO

3.Cleanany impurities on thesurface of thesocketand spigottoensuretheconnectionsurfaceisclean.

4.lnstall he gasket ring into the spigot mounting groove.

5.Apply the lubricant on the inner surface of the pipe socket and the surface of the spigot gasket ring. <br>7.After the connection is complete,remove the pipe pullers,and check the connection condition.

6.Thespigotendof thepipeisevenlydrawn into thesocket using pipe pullers positioned on both sides of the pipe

CG 力

VII.Design

1.General Provisions

1.1Theplanimetricpostionandelevationofplasticdrainagepipesshouldbedeterminedcomprehensivelyconsideringfactorssuchas terrain,oiluaityoudwatevelodioslanddergroudaciliiputndstrctio
1.2Plasticdrainagepipessouldbelaidintraightaignments.Wenangedoruredlaingisrequiredduetospecificicumstancste maximumalowabledeflectionangleofthepipejointand theminimumallowablebendingradiusoftepipeshouldcomplywiththe currentnationalstandards.

1.3 The designed service life of plastic drainage pipes should not be less than 5O years.

LESSO

1.4Thestructuraldesignofplasticdrainagepipesshouldbecalculatedandverifiedaccordingtothefolowing twolimitstates:
1.4.1Intermsofultimatelimitstate,thecalculationshouldincludethringsectionstrengthofpipestructure,theringsectionbuckling stability,and thepipeanti-floatingstability.
1.4.2 In terms of serviceability limit state,the pipe ring section deformation should be checked.
1.5Plasticdrainaepipssouldbedesignedforopressregravityflowndtheirstructuralcalclationssoudbecaedoutacodig to the design theory of flexible pipes.
1.6The calculatedcentral angle (2α)of thearcshaped soil orsand-gravel bedding of thepipe should bereduced by 3 0 ^ { \circ } based on the designedcentralangleofthearcshapedsoilorsand-gravelbedding.Thedesignedcentralangleofthearcshapedsoilbeddingor sand-gravel bedding of the pipe should not be less than 1 2 0 ^ { \circ }
1.7Forplasticdrainagepipesenclosedinaconcreteprotectivecasingstructure,theconcreteprotectivestructuresouldbearexteal loads.Continuous and ful-length pipe encasement from one inspection chambers to the next is required.
1.8Plasticdrangppesadotaddngfoundation;itistrictlyproidtouedistiectlypprteies.

2. Pipe Layout

2.1Thepositioningofplasticdrainagepipes inrelationtootherundergroundpipes,buildings,ndstructuresshouldmeetthe
following requirements:
2.1.1 The laying and maintenance of the pipes should not cause interference or affction to other systems;
2.1.2Damagetoasticdrainagepessoldecttefoundatiosfarbydnsoructuresotamnatediingate
2.1.3 Plastic drainage pipes should not be directly buried in vertical overlap with other utity pipes.
2.1.4 Plastic drainage pipes should not be passed under the foundations of buildings or large-scale structures.

2.2Plasticdrainagepipesshouldbelidbelowthesoilfreezingine.Thesoilcoverthicknessabove thetopoftepipeshouldnotbeless than 0 . 6 m under pedestrian walkways,and shall beat least 0 . 7 m under roadways.

2.3Theminimumpipediameterandthecorespondingminimumdesignslopeformunicipalplasticdrainagepipesoutsideresidential quartersshouldcomplywiththespecificationsdescribedinTable2.3-1whiletheminimumpipediameterandthecorrsponding minimumdesignslopeforplasticdrainagepipesinsideresidentialquartersshouldmeetthespecificationsdescribedinTable2.3-2.

LESSO

2.4Plastic drainage pipe systems should be equipped with inspection chambers.The inspection chambers should be installed at pipe junctions,changes in pipedirection,alterations in pipediameter or slope,drop points,and at certain intervals along straight pipe sections.The maximum spacing of inspection chambers along straight pipe sections should comply with the specifications in Table 2.4-1.

3.Hydraulic Calculation

3.1The flow velocityand discharge in plastic drainage pipes can becalculated according to the following formula:

Q Discharge ( m ^ { 3 } / \mathsf { s } ) A Wetted cross-sectional area ( \mathsf { m } ^ { 2 } ) v Flowvelocity ( \mathsf { m } / \mathsf { s } ) n -Pipewall roughness coefficient; R Hydraulic radius (m); I Hydraulic slope.

3.2Theselectinoftheppealroughessoeficient(nforplasticdranagepipessouldbedeterminedthroughcomprehensiveanalysis basedontestdata,withvaluesrangingfrom0.oo9 toO.011.Intheabsenceoftestdata,itisadvisable totakethevalue of 0.011.

3.3The maximum design flow velocity for plastic drainage pipes should not be greater than 5 . 0 { m / s } .Theminimum design flow velocity fo sewagepipesshouldnotbe less than 0 . 6 { m / s } under the design filing grade.Theminimum design flow velocity for rainwater pipes and combined drainage pipes should not be less than 0 . 7 5 { m / s } under full flow conditions.

4.Load Calculation

4.1Thestandardverticalsoilpressureon thetopofplasticdrainagepipescanbecalculatedusing thefolowing formula:

Where: qsv,k Standard vertical soil pressure on the top of the pipe per unit area ( \mathsf { k N } / \mathsf { m } ^ { 2 } ) \mathfrak { g } （204 Gravity density of backfill soil, typically takenas 1 8 1 < N / \mathsf { m } ^ { 2 } （20 { \mathfrak { g } } ^ { * } （20 Gravity density of the soil cover within the underground water range,typicaly taken as \scriptstyle 1 0 \mathsf { K N } / \mathsf { m } ^ { 3 } { \mathfrak { g } } _ { \mathfrak { w } } （20 Gravity density of underground water, typically taken as \scriptstyle { 1 0 \mathsf { K N } } / \mathsf { m } ^ { 3 } H _ { s } （20 Depth of soil cover above the top of the pipe ( \mathsf { m } ) \boldsymbol { H } _ { { \Sigma ^ { \ w } } } （20 Depth of underground water above the top of the pipe ( \mathsf { m } ) #

4.2Thevariableactionloadsonplasticdrainagepipesshouldincludegroundvehicleloadsandheapedloadsatingonthepipes.Vehicle loadsandheapedloadssouldotbonsideredmutaneouslyndteloadwitgreaterefectsouldbeselectedTeicleload level shouldbe determined based onactual traffic conditions.

4.3Thestandardverticalpressuretransferedtothetopoftheplasticdrainagepipefromthegroundvehicleloadcanbedeterminedas follows (te quasi-permanent value coeficient can be taken as \big \Psi _ { q } = 0 . \dot { 5 } ）

4.3.1Thetandardverticalpressuretransferredtothetopofthepipefromasingletireload(Figure4.3.1)canbecalculatedusingthe following formula:

Figure4.3.1DistributionofPressureTransferredfromaVehicleSingle-tire

(b)Pressure Distribution Along the Tire Contact Length Direction

(a)Pressure Distribution Along the Tire ContactWidth Direction

4.3.2Forooeingoirdstomdctasferdtoofiaatesflosre

Figure4.3.2Distributionof theCombinedEffectofTwoorMore Single-rowTireLoadsTransferredfromGround Vehicles

Where: q _ { \nu k } 一 Standard vertical pressure per unit area transferred from ground vehicle load to the topof the pipe ( { \mathsf { k N } } / { \mathsf { m } } ^ { 2 } ) μd -DynamiccoeficientofthevehicleloadcanbeselectedaccordingtospecifiedvaluesinTable (4.3.2-1)ofthismanual; （204号 \scriptstyle Q _ { \nu k } —Standard single-tire load of the vehicle ( \mathsf { k N } ) a Single-tire contact length ( \mathsf { m } ) ： （204号 b 1 Single-tire contactwidth ( \mathsf { m } ) n -Numberof tire loads; d _ { j } 1 一Net distance betweenadjacent tire loads (m).

4.4 The standard ground heaped load q _ { \nu k } can be taken as style 1 0 \ k N / \mathsf { m } ^ { 2 } ,with a quasi-permanent value coefficient sf { y } _ { q } = 0 . 5

5.Ultimate Limit State Calculation

5.1Whencalculatingtheingsectionstrengthofplasticdrainagepipesundertheutimatelimittate,thebasicloadcombinationshouldbe used,andall load values taken should be design load values.

5.2Underanexterapressureload,themaximumringsection(tensile)compresivestressdesignvalueoftheplasticdainagepipe shouldnotexceedthedesignvalueofthe(tensile)compressivestrength.Thecalculationofthepipe’sringsectionstrengthshould follow the limitstate expressionbelow:

LESSO

Where:

O— Maximum ring (tensile) compressive stress design value of the pipe (MPa);
\boldsymbol { γ } _ { 0 } —Pipe importance coefficient: 1.0 for sewage pipes (including combined drainage pipes),and 0.9 for rainwater pipes;
f 一Ring bending (tensile) compressive strength design value (MPa) of the pipe.

5.3Themaximumring bendingstressdesignvalueforplasticdrainagepipescanbecalculatedusingthefollowingformulas:

(5.3-1-1)

Where: D _ { { f } } Form coefficient can be taken based on the specified values in Table 5.3 of this manual; K _ { { d } } （20 PipedeformationcoeffcientshallbedeterminedinaccordancewiththeprovisionsspeifiedinTable6.ofthismanualbasedonthe calculated central angle 2α of the soil arc bedding; D _ { { o } } （204号 Pipe calculation diameter (m); D _ { \imath } （204号 Outside diameter of the pipe ( \mathsf {mm } ) （20 S _ { \mathfrak { p } } （204号 Pipe ring stiffness ( k N / \mathsf { m } ^ { 2 } ) E _ { { { p } } } Pipematerial's elastic modulus ( { \mathsf { k N } } / { \mathsf { m } } ^ { 2 } ) Moment of inertia of the pipe wall per meter of the longitudinal section of the pipe (mm); E _ { { d } } （20 Combined deformation modulus of the soil around the pipe ( k N / \mathsf { m } ^ { 2 } ) shall be determined by testing or based on relevant standards if without testing data; （204 γ _ { G } （204号 Partial coefficient ofsoil cover loadabove the top of thepipe:1.27; （204号 γ _ { \varrho } （2 Partial coefficient of ground load above the top of the pipe: 1.40; （20 q _ { \nu , k } （204 Standard vertical soil pressure above the top of the pipe per unit area ( 1 < N / \mathsf { m } ^ { 2 } ) shall be calculated by the formula (4.1-1); qsvk Standard vertical pressure fromground vehicleor heaped loadstransmited to the topof thepipeperunit area ( k N / \mathsf { m } ^ { 2 } ) shall be adopte defined in Sections 4.3 and 4.4 of this manual; { \sigma } _ { c r } （204 Design value of maximum ring bending tensile stress for the pipe wall ( \mathsf { k N } / \mathsf { m } ^ { 2 } ) #

5.4Thebucklingstabiltofplasticdrainagepipesectionsshouldbecalculatedbasedontheadversecombinationsofvariousactions. Allactions shalladopt standard values,and the ring stability resistance coeficient KS should beat least 2.0. 5.5Underexternalpressure,theringstabitycalculationforthepipewallsectionsshould meetthefolowingrequirements:

5.6The standard valueof theadverse combinationof vertical action above the top of the plastic drainage pipe can be calculated according to the following formula:

Where:

F _ { c r , k } （204号 Standard critical pressure for pipe wall instability ( k N / \mathsf { m } ^ { 2 } ) canbe calculatedaccording to the formula (5.7) of this manual;
F _ { \nu , k } （204号 Standard vertical pressure above the top of the pipe fromvariousactions ( { \mathsf { k N } } / { \mathsf { m } } ^ { 2 } ) can becalculated
K _ { s } Ring stability resistance coefficient of the pipe. according to the formula (5.6) of thismanual;

LESSO

5.7The standard critical pressure of the pipe wall instability for the plasticdrainage pipe can be calculated using the following formula:

Where: F _ { c r , k } Standard critical pressure for pipe wall instability ( k N / \mathsf { m } ^ { 2 } ) \nu _ { p } Poisson’s ratio for the pipe can be typically taken as 0.4 for thermoplastic pipes; \mathsf { x } （204号 Instability calculation coefficient for the pipe S _ { \mathfrak { p } } （20 Pipe ring stiffness wall:5.66; ( { \mathsf { k N } } / { \mathsf { m } } ^ { 2 } ) E _ { { d } } Combined deformation modulus of the soil around the pipe ( { \mathsf { k N } } / { \mathsf { m } } ^ { 2 } ) #

5.8Forplasticdainagpipesuridelowthgroundwatereelondergroundaterveltantifoatingsabilyofteestructure should be calculated based on the design conditions.Alloads should be takenat their standard values. 5.9Theanti-floating stability of the plastic drainage pipe should meet the following requirements:

(5.9-1) <br>(5.9-2)

Where:

FG, Standard value of permanent anti-floating actions (kN);
a F _ { s w , k } 一 Sum of standard self-weight of the soil layers above the underground water level (kN);
a F _ { _ { a v , k } } ^ { \prime } Sumof standard vertical action from below underground water level to the top of the pipe ( k N ) = （204号 G _ { p } Standard self-weight of the pipe (kN); Ffuk Standardbuoyancy forceshal beequal to the productof the pipe’sactual displaced volumeand the densityof the underground water (kN); （204号 K _ { f } -Anti-floating stability resistance coefficient of the pipe:1.10.

LESSO

6.Serviceability Limit State Calculation

6.1The load combination for the ring section deformation check of plastic drainage pipes should be calculated according to the quasipermanentcombination.
6.2 Under external pressure,the vertical deformation of plastic drainage pipes can be calculated using the following formula:

Where: { w _ { d , \operatorname* { m a x } } } （204号 Maximum vertical deformation of the pipe under the combined effect ( \mathsf {mm } ) （204 K _ { d } （20号 Pipedeformationcoeffcientshallbedeterminedbasedonthecalculatedcentralangle2αofthepipebeddingconditions,as specified in Table 6.2 of this manual; （204号 q _ { s \nu , k } （20 Standard vertical soil pressure above the top of the pipe per unit area ( k N / \mathsf { m } ^ { 2 } ) shall be calculated according to the formula (4.1-1); （204号 q _ { \nu k } （20 Standard vertical pressure from ground vehicleor heaped loadstransmited to the topof thepipeperunit area ( { \mathsf { k N / } } { \mathsf { m } } ^ { 2 } ) shall be adopted D _ { \iota } （204 de ya Quasi-permanent value coefficient for variable loads: 0.5; S Pipe ring stiffness ( k N / \mathsf { m } ^ { 2 } ) ： E _ { d } ^ { ' } （20 Combined deformation modulus of the soil around the pipe ( k N / \mathsf { m } ^ { 2 } ) shall be determined by testing or based on relevant standards if without testing data; D _ { 1 } （204 Outside diameter of the pipe (mm).

6.3Underexteralpressureloads,tevrticaldiameterdeformationrateoftheplasticdrainagepipeshouldnotexceedtheallowable deformation rate of the pipe, [ \boldsymbol { \rho } ] = 0 . 0 5 .The requirement should satisfy the formula (6.3).

Where: r Vertical diameterdeformationrateof the pipe; [] Allowable vertical diameter deformation rate of the pipe; Wd Long-term vertical deflection of the pipe under external pressure ( \mathsf {mm } ) can be calculated according to the formula (6.2-1); D _ { \circ } （20 Calculated diameter of the pipe ( \mathsf {mm } ) #

7．Pipe Connection

7.1Plastic drainage pipes are divided into two forms of connection: rigid and flexible connections The connection methods for diferent types of pipes can be selected according to Table 7.1.

Notes:

1. In the table, " \bigtriangledown * \bigtriangledown ^ { \prime \prime } indicates priority adoption;"∠"denotes optional adoption.
2. ① inthe table indicates thatan electrofusion welding tape connection can be adopted after inner lining patching.
3. ② in the table signifiesthatan electrofusion welding tape connection can beapplied after inner wall welding.
4. ③ inthetablespecifies thatasocket-and-spigot elasticgasketringcanbeusedafter thesocketand spigotaremachined.

7.2Whenlaingplasticnageisireseteitesilrngssinificantlereteiteaegryiasse the seismic fortification intensity is 8 degrees or higher,a flexible connection shall be used.
7.3Whenconctingplasticdaageppeswithplasticinspectioambersflexibleonectiosalleprefeedforipswitoutside diameter of more than 1000mm.

8.Foundation Treatment

8.1Plasticdrainagepipesshouldbelaidonnaturalfoundationsndthechracteristicvalueoffundationbearingcapacityfaksouldot be less than 60kPa.
8.2Whenlayingplasticdrainagepipes inlocationswithunfavorablegeologicalconditions,thefoundationshouldfirstbetreatedin accordance with the foundation treatment specifications before pipe laying.
8.3Whenlayingplasticdrainagepipesiniteswithghgroundwaterlevelsandhighsoifluiditythegeotextilessouldbelidalongthe trenchbotomandslopesonbothsidesforprotectioifthereisaposibitoflossofinegrainedsoilparticlesaroundthepes;the density of these geotextiles should not be less than 2 5 0 { { g } } / { { m } } ^ { 2 }
8.4Ifthefoundatiotisdifrssignificantlyintlingectioneplacementoftddinglyeoterfctiesure shouldbetakentoreducethediferentialsetlementofplasticdrainagepipes.Tethicknessoftheeddinglayershouldbedetermined according to site conditions,but should not be less than 0 . 3 m

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9.Backfill Design

9.1Thebeddingusedforplasticdrainage pipesshouldbeconstructedwithmedium-coarsesandorfinegravelarcshaped soil.The dimensionsof thearcshapedsoilbeddingabove thebottomofthepipeshouldbedeterminedaccordingtothepipestructural calculatin.Tethicknessofthearticialarcshapedsoilbeddingbelowthebottomofthepipecanbecalulatedaccordingtothe followingformula,andshouldnotbegreater than 0 . 3 m

Where:hd — Thickness of the artificial arc shaped soil bedding below the bottom of the pipe ( \mathsf { m } ) DNNominal diameter of the pipe ( \mathsf { m } ) #

9.2Thedesignedwidthofthetrenchatthehaunchingcenterofplasticdrainagepipesshouldbedeterminedbasedoncomprehensive considerationdingtipt,odigocdaitacentpioissofc constructioncodios.Adiolgeofmpactioofackfiluldeteridaccdingtoeleantisio of this manual.

9.3The degree of compaction of backfill soilat locationsmore than 0 . 5 m above the top of plastic drainage pipes should be determined according to the corresponding sites or road design requirements,and should notbe less than 90 % .Thebackfillsoilatvarious locations less than 0 . 5 \mathsf { m } above the top of the pipe should comply with the provisions described in Table 9.3.

Note:The degree ofcompaction of backfillsoil shall be expressed asa percentage relative to 100 % of the maximum dry density obtained fromthelightcompactionstandardtestunlessotherwisespecifiedinthedesignrequirementsthattheavycompactionstadardis to beadopted.

Vlll. Construction

1.General Provisions

1.1Beforetheinstalltionofplasticdrainagepies,theconstructionpartyshallprepareasuitableconstructiondesignwichouldbe implementedafterapproval inaccordancewith the specified procedures.

1.2Whencomplingtheonstructidsignforpasticdrainageppestheipeingstis,trenchackfilmateralsandteieef compaction,aswellstheconditionsoftheundisturbedsoilonbothsidesoftepipesallbeverifiedaccordingtotemaimum allowablesoilcoverthicknessabovethetopofthepipeasspeciedinthedesign.Ifanydiscrepancywiththedsignreqrementsis found,arequestfordesignmodificationororrspondingtechicalmeasuresshallbeimplementedtoensuretheipeload-bearing capacity.

1.3PlasticdranagepipssalundergoincomingispectionTeproductquaityerticateandinspectioeportprovidedbyteterial suppliershallbeeckedPipeanditingshallbeverifiedaccdingttdsignequirements.heappearanceofachpealle inspectedonebyoneaccordingtotheproductstandardanddesignrequirements.Keysamplingispectionsshallbeconductedniems

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1.4Whenconnectingplasticdranagepipes,teimpuriesisideteessalleeanedAttedofdailworkallppeesale sealed with temporary blocking measures.
1.5AfterthcoetiooflastiageipimpleedtejintaitysalspectdAqifidjintsustd and their quality shall be re-inspected after reworking.
1.6Beforconnectigplasticdanagepipestoinspectionhambers,thefoundatioattebotooftheinspectiochambersafirste accepted.Ifioudatodtiosueeaedaditeeevoableio orsoillayers,theinspectionchamberconnectioncanonlybecarriedoutaftertreatment tomeet thedesignrequirements.
1.7Whenconnectingplasticdrainageppesitspetiocambersanoverexcavatedunfild)sectiofteottmofteipal bepromptlybackfiledandcompactedinlayerswithgravelornaturalygradedsandandgravelbeforepipeconnection.Thedegreeof compaction shall comply with the provisions described in Section 9.3 of this manual.
1.8Duringthelagadbackflingofplasticdrainageppesthereshallenwateaccuulatinorfreengatthebottomofthtrech.In areaswherethegroundwaterlevelishigherthantheelevationofthebotomoftheexcavatedtrench,thegroundwaterlevelshallbe lowered to at least 0 . 5 \mathsf { m } below the lowest point of the trench bottom.

2.Material Transportationand Storage

2.1The transportation of plastic drainage pipes shall comply with the following provisions:
2.1.1Theysalddiedaltopldadapntdfoin non-metalic ropes (or straps) shall be used for hoisting.
2.1.2Theyshallacdontallurintasporationdalloudandiditmealios(otras) nosharpprotrusionsthatmaydamagethepipesatthestacking locations,andsunprotectionmeasuresshallbetakenasappropriate.
2.2The storage of pastic drainage pipes shallcomply with te following provisions:
2.2.1Theyshalbestoredinawelventlatedwarehouseorsedandeptawayfromeatsources;sunprotectionmeasuresshalletaken for outdoor storage.
2.2.2Theymustneverbestoredtogetherwithoilsorchemicals;storageareasshallbeequippedwithfrepreventionmeasuresandfire fighting facilities.
2.2.3TheyshallbstackedhorizontalyflatsupportsorthegroundPpeswihsocketsshallbestackedateratelyatbothditha height not exceeding 3m;appropriatesafety measures toprevent collapseand pipe deformationshal be taken.
2.2.4Theysalordpaatelycdingtirentspcifiatios,esndtyndtfistnisttprincilale observed.
2.2.5Pipesandfitingsshouldnotbestoredforalongtime;storagetimeinthewarehouseshouldnotexceed18monthsfromthedate of production.

3.Trench Excavation and Foundation Treatment

3.1Beforetheexcavationoftherenchforplasticdrainagepies,thetemporarybenchmarksieaisontrolilesndeevatiopiles shallberechecked.Tealowabledeviationofteconstructionsurveyshallcomplyiththeprovisionsofthecurrentnationalstandard Code for Construction and Acceptance of Water and SeweragePipeline Works (GB 50268).
3.2Theexcavationwidthatthbottmoftetrenchforplasticdrainagepipesshallmeetthedesignreqirements.Ifnospecificidthis given,it canbe calculated according to the following formula:

Where: B Excavation width at the bottom of the pipe trench (mm); D _ { \imath } （204号 Outside diameter of the pipe (mm); \mathbf { b } _ { \mathfrak { n } } Width of the working surface on one side of the pipe (mm) canbeselectedaccording toTable 3.2.Ifadrainage ditch isrequired at the bottom of the trench,b1 shall be increased according to the requirements of the drainage ditch; \mathbf { b } _ { 2 } Thickness of the support on one side of the pipe: （204号 1 5 0 {mm } to 2 0 0 \mathsf {mm }

3.3Thedistancefromthepostionoftesidestackedsoiloftheplasticdrainagepipetrenchtotheedgeofthetrenchmouthshouldnotbe less than 1 . 0 \mathsf { m } ,and the height of the stacked soil should not exceed 1.5m.

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3.4Theexcavatiooftasticainaeiptrnchsaltriclotrovatiooftfoundtio;tndistubedsoattoudation shall not be disturbed.The undisturbed soil 0 . 2 \mathsf { m } \mathsf { - } 0 . 3 \mathsf { m } above the designed elevation of the foundation shall be manually cleaned to the designedelevationbeorepipeling.Iaseofoverexcavatiooisturbanceoftefundationaturalygadedsndgraeteas orcrushed stones with a maximum particle size of less than 4 0mm shall be used for levelingand compaction. Thedegreofompactionsalletthqirementsoftdigompactionandncelaneussoilshallbeusedforcfiling Iftherearesharporhardobjectsatthebottomofthetrench,theymustberemovedandbackfiedwithsand-gravelforteatment.
3.5Thefoundationoftheplasticdrainagepipeshallmetthedesignrequirements.Iftestrengthoftenaturalfoundationofthepipe cannot meet the design requirements,it shall be reinforced accordingly.

3.6 The foundation treatment of plastic drainage pipes shall comply with the following provisions:

Figure3.6 GrooveatthePipe Joint : Undisturbed soil foundation;2: Medium-coarse sand bedding;3: Groove;4: Groove length; 5:Groove width

3.7For standard soil, a 1 5 0 \mathsf {mm } medium-coarse sand bedding shallbe laid on the undisturbed soilfoundation below the botom of the pipe.
3.7.1Forsoftsoioundatios,iftarigpacityftfundatiosstanthsiiremetoifeaingpaitte foundationismpromiseduetstructiowateigrecavatioraostatctdsturbdilt foundationshallbereinforcedaccording to the design requirements.Afterreaching the specifiedbearing capacity,a 1 5 0 \mathsf {mm } mediumcoarse sand beddingshall be laid.
3.7.2Whenthebotomofthetrenchisfledwitocksorardbjects,thethicknessofthelidmedium-coarsesandbedingshallotbe less than 150mm.

4.Pipe Installation

4.1Beforeloweringtasticraagesintotrchforoctiostatireifatioetectiotctaer ofthe pipecross-sectionshallbemeasured firstandmarked.

4.2Speciatoallsdfokesotectrofutioectrofsioaotiotsii connection.During the instalation of plastic drainage pipes,all connectionpartsand seals shallbe cleaned.

4.3Theappropriatepipeloweringmethdshallbedeterminedaccordingtothediameteroftheplasticdrainagepipeaswelasthe conditionsoftetrenchandtheconstructionmachineryWhenppesreloweredmanualy,strap-typenon-metalicopessallbesed tosmoothlyslidethepipeintothetrench;thepipeshallnotberoledintothetrenchfromthetopofthetrench.Whenmechanical loweringisdoted,trap-tyenonmetallcopeshallmploedforstingndteremustbolsstantoligt duringhoisting.ougthbretingisotoedandtoweingitorenchalableoutimpactingtrch wall or the trench bottom.

4.4Wheintaliastiaesisaliiectwaterfondoeallagsttiof waterflow.Teinstalltionshouldbecarredoutfromtedownstreamtotheupstream.Rigidcushionblocksshallnotbeusedoeter side of the pipe for pipestabilization.

4.5The operation of socket-and-spigot electrofusion connection shall comply with the following provisions:
4.5.1Wipe the connection parts clean,and mark the insertion depth on the spigot end.
4.5.2If theout-of-roundness of the pipeaffects instalation,apipe rounding tool shallbeused to round thepipe.
4.5.3Insert the spigot end into the socket to the position of the insertion depth line,and check the fit.
4.5.4Beforepoweringttespoingoetorsturtyeteisnfijntsittol
4.5.5 The power-on heating time shall comply with the provisions of relevant standards.
4.5.6Duringthecolingperiodforelectrofusionconnection,donotmovetheconnectorsorapplyanyexternalforcetothem.

4.6Durigconstructionintheainyseasonoinareaswithaighgroundwaterlevelforplasticdrainagepipesmeasurestopreventepipe fromfloatingsallbaken.Ifteiparesoakedinateftinstalltionutbeforebackfilngteipecenteadtipeivert elevationshalbemeasuredndsualinspected.Ifisplacement,flatingsalignentarefound,tareildo bereworked.
4.7Whenthslosiaeddsctduslyifrts thetopoftepipecannotmetthestandardrequirements,teoveralldeformationmodulusofthesoilonthepipesidesallbeecked accordingtothemechanicaloadoftheroadsubgradeconstruction;thefollowingreinforcementmethodscanbeadoptedaccordingto actual needs:

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4.7.1For plastic drainage pipes with a nominal diameter less than 1 2 0 0 {mm } ,the method of first compacting the subgrade followed by excavationforpipelayingcanbeadopted.Ifthefoundationstrengthcannotmetthedesignrequirements,thefoundationshalbe treated first,and then excavated.
4.7.2Forthebackfilingofthetrenchonthepipeside,materlswithalargedeformationmodulussuchassand-gravel,ig(medium) calcium flyash,and lime-fly ash soil can be used.
4.7.3The above two reinforcement methods are carried out simultaneously.

4.8Theconnectioofplasticdrainagepipestoasticoncreteorasonryispectioncamberscanbemplementedincodanceih relevantregulations.

PE Spirally Enwound Structure-wall Pipe Type C

5.Trench Backfilling

5.1Aftertheplasticrainagepseldandavepasdvisualispectionttrenchackfilngsallaedutimmedateee thetightnesstetexceptfteexpoedjintpartsteckfilingeightoothsidesofeeadabovethtoofteoud not beless than0.5m;after the tightness testis qualified, theremaining partsshallbe backfiled in time.

5.2Beforebackfilnttrenchsallspctedremustbowateccmulatiointrechndmpuriscick stones,and wood blocks shall be removed.

5.3Trenchbackflnsaleadutsmmetricalyandevenlfroothsdsofteatteaetieanditsalsdta theplasticdrainagepipedesnotshift.Ifnecessary,temporaryrestraintsshallbetakenforthepipetopreventitfomfloating.

5.4Backfilingaroundinspecionhambers,tterietsandoherauiarystructuresshalomplywitthefollowigproisios:
5.4.1Backilnroundteambercadutsimutaneuslitetrenchacfilngoftpipeheeisstble stepped joint shall be left.
5.4.2Bacfilingadcompactionaroundthemanlecambershallbecaredoutsymmetricalylongthecenteroftemanoleambe and no compaction shall be missed.
5.4.3The backfill material shall be closely attached to te chamber wall after compaction.
5.4.4Aroundtemanoleamberwithinteoadsurfacernge,ateralssuchasmesoand,andgravelshalleusedforiling; the backfilling width shall not be less than 4 0 0 \mathsf {mm }
5.4.5 Soil from the trench wall must not be used for backfilling.
5.5Whenbcilncstsilodotddcfit contain stones,bricks,or other impurities.
5.6Therangeofthedesignedcentralangleofthepipebeddingoftheplasticdrainagepipesallbefiledandcompactedwithmediumcoarsesand,which shallbe inclosecontact with the pipe wall nosoil orother materials shallbeusedforfiling.
5.7Backfillsiltckfilateralsalraspedintothnchmmetrialyfromothssoftncandallotbe directly backfilled onto the plastic drainage pipe to avoid damaging the pipe and its joints.
5.8The loosepavingthicknessforachlayerofbackfilsoilinplasticdrainagepipeinstalltionsshallbeselectedaccordingtothe compaction tools used and the provisions given in Table 5.8.

5.9Whentherenchissupportedbystlsheetpiles,thepilescanonlybepulledoutafterbackfilngreachesthespeciedeightAfter thestelsheetpilesarepuledout,thevoidsshallbebackfiledassoonaspossibleandfiledtightlyWhensandisusedforfiling watercanbeusedforcompaction.Whentherearerequirementsfortheimpactonthesuroundingenvironment,simultaneousgrouting duringpileremoval canbeused.

5.10Duringttrenhackfilnofastanaestrtleforatiooftssaltricotroldtsde diameterof the pipes is greater than 8 0 0 \mathsf {mm } ,temporary vertical supportscan be installed inside the pipe,or suitable pre-deformation measurescanbetaken.Duringbackfiling,theverticaldeformationcausedbyverticalloadscanbecompensatedforbytheertical reversedefomationtatoccursuringackflingndompactionoftepipeaunchingareas;oweveritshallbontroledwiin thedesign limits for the vertical deformation.

5.11All backfilingconstruction in thepipeareaofpasticdrainagepipesshallcomplywiththe following provisions: 5.11.1 From the bedding area of the bottom of the pipe to 0 . 5 m above the top of the pipe,manual backfilling and the compaction with light compaction equipment must be adopted; mechanical backfiling with bulldozers is not allowed.

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5.11.2 Backfiling and compaction shallbecarredout in layers,with each layer of backfillsoil not exceeding 2 0 0 \mathsf {mm } Unilateral backfilling and compaction must be avoided.
5.11.3 When mechanical backfiling and compaction are adopted for an area more than 0 . 5 \mathsf { m } above the top of the pipe,they shall be carried out evenly from both sides of the pipe axisat thesame time.The soil must be compacted and rolled.
5.12Thenumberofcompactionpasesforeachlayerofsoilduringbackfilingofplasticdrainagepipesshallbedeterminedthroughonsitetestsbasedontherequired degree of compaction,compactiontols,loosepaving thicknes,and watercontent.
5.13Whenhaompactionmaineryissedfompactioenhaiclestraveonteackflso,heresallain thicknessofcompactedbackfllsoilabovethetopofthepipe.Theminimumthicknessshalbedeterminedthroughcalculationbased on the specifications of the compaction machinery and the design bearing capacity of the pipe.
5.14Thetrenchcfilnfpasticaesinarseasolsbleseaspasiesendrmaroal comply with the design requirements and the provisions of local engineering construction standards.
5.15Thedegrofcompactioofthbackfiloiandacfilmaterialsforplasticrainagepipessallomplyithteprovisiosd in Table 9.3 of thismanual.

IX. Inspection

1.Tightness Test

1.1Sewagepdwateednateisiblieildst
undergo a tightness test; they can be put into operation only after passing this test.
1.2Thetightesststofplasticdrainageppessallecariedoutinsectiosaccordigtothedistaceetweeninspectioncambs;te lengthofeachtestsectionshouldnotexceed5consecutivechamberspansandthetestshalbecaiedoutwiththeinspection chambers included.
1.3Thetightness testof plasticdrainagepipes maybeperformedusingthe water-tightness testmethod.Theoperationshal be implemented inaccordancewith the provisionsof relevantstandards.
1.4 During the tightness testof plastic drainage pipes,visual inspection should reveal no obvious water seepage.
1.5The maximum allowable water seepage of the pipe shal be calculated according to the following formula:

Where: Q _ { s } Maximum allowable water seepage [ \mathsf { m } ^ { 3 } / 2 4 \mathsf { h } * \mathsf { k m } ] { \bf d } _ { i } Inside diameter of the pipe ( \mathsf {mm } )

2.Deformation Test

2.1Afterthetrenchbackfilingoftheplasticdrainagepipeeachesthedesignelevation,teerticaldeformationofthepipesale measuredwithin12h-24h,and thepipedeformationrateshallbecalculated.

2.2 When the insidediameter of the plastic drainage pipe is less than 8 0 0 \mathsf {mm } ,the deformation of the pipe can be detected by methods suchas a circular mandrel or closed-circuit television;when the inside diameter of the pipe is 8 0 0 \mathsf {mm } ormore,manual detection inside the pipe canbeadopted,and themeasurement deviationshall not exceed 1 \mathsf {mm }

2.3The deformation rate of the plastic drainage pipe shall not exceed 3 % ：if it does,the following treatment measures shallbe taken:
2.3.1When the pipe deformation rate exceeds 3 % but does not exceed 5 % ,the following measures shall be taken:
2.3.1.1 Excavate the backfillsoil to expose 8 5 % of the pipe; the area within 0 . 5 m around the pipe shall be excavated manually;
2.3.1.2 Inspect the pipe,and if any damage is found,repair or replace it;
2.3.1.3Backfilmaterialsthatmtthequieddegreofompactionsouldeusedeforeteyrebackfiledagainndmpacted according to the required degree of compaction;
2.3.1.4 Re-detect the pipe deformation rate until it meets the requirements.
2.3.2When the pipe deformation rate exceeds 5 % ,the pipe shall be excavated,and the design organization shallbe consulted for further treatment.

3.Inspection of Compaction Degree of Backfill Soil

3.1Thedegreeofompactioofthbackfiloilitheplasticdrainagepetenhshallomplyiththprovisionsdesrbediction93 of this manual.
3.2Thedegreofcompactionofbackflsilinherpartsofteplasticrainagepipesystemsalbimplementedinaccordancewitthe currentnational standard Code for Constructionand Acceptanceof Waterand SeweragePipeline Works (GB 50268).
3.3Theinspectiometdforthedegreeofompactioofthebackiloilintheplasticdranageppetrenhshallbselectedaccodigto specific conditions.

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