Structural design of buried pipelines under various conditions of loading - Part 2: Summary of nationally established methods of design

In addition to EN 1295-1, this Technical Report gives additional guidance when compared with EN 1295-1 on the application of the nationally established methods of design declared by and used in CEN member countries at the time of preparation of this document (see informative Annex A).
This Technical Report is an important source of design expertise, but it cannot include all possible special cases, in which extensions or restrictions to the basic design methods may apply.
Since in practice precise details of types of soil and installation conditions are not always available at the design stage, the choice of design assumptions is left to the judgement of the engineer. In this connection the document can only provide general indications and advice.

Statische Berechnung von erdverlegten Rohrleitungen unter verschiedenen Belastungsbedingungen - Teil 2: Zusammenstellung national eingeführter Berechnungsverfahren

Calcul de résistance mécanique des canalisations enterrées sous diverses conditions de charge - Partie 2: Résumé des méthodes nationales de dimensionnement

En complément a l'EN 1295-1 et par rapport a cette derniere, le présent Rapport technique donne des lignes directrices supplémentaires pour l'application des méthodes de calcul reconnues au plan national, déclarées et utilisées dans les États membres du CEN au moment de la préparation du présent document (voir l'Annexe A informative).
Le présent Rapport technique est une source importante d'expertise sur le calcul de la résistance mécanique, mais il ne peut inclure tous les cas spéciaux possibles, pour lesquels des extensions ou des restrictions des méthodes de calcul de base peuvent s'appliquer.
Puisque dans la pratique des détails précis sur les types de sols et sur les conditions de pose ne sont pas toujours connus au stade du projet, le choix des hypotheses du projet est laissé a l'appréciation de l'ingénieur. De ce fait, le document peut seulement donner des indications et des conseils généraux.

Projektiranje vkopanih cevovodov pri različnih pogojih obtežb – 2. del: Pregled nacionalnih metod projektiranja

General Information

Status
Published
Publication Date
30-Nov-2005
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Dec-2005
Due Date
01-Dec-2005
Completion Date
01-Dec-2005

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SLOVENSKI STANDARD
SIST-TP CEN/TR 1295-2:2005
01-december-2005
3URMHNWLUDQMHYNRSDQLKFHYRYRGRYSULUD]OLþQLKSRJRMLKREWHåE±GHO3UHJOHG
QDFLRQDOQLKPHWRGSURMHNWLUDQMD

Structural design of buried pipelines under various conditions of loading - Part 2:

Summary of nationally established methods of design
Statische Berechnung von erdverlegten Rohrleitungen unter verschiedenen
Belastungsbedingungen - Teil 2: Zusammenstellung national eingeführter
Berechnungsverfahren

Calcul de résistance mécanique des canalisations enterrées sous diverses conditions de

charge - Partie 2: Résumé des méthodes nationales de dimensionnement
Ta slovenski standard je istoveten z: CEN/TR 1295-2:2005
ICS:
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
SIST-TP CEN/TR 1295-2:2005 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 1295-2:2005
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SIST-TP CEN/TR 1295-2:2005
TECHNICAL REPORT
CEN/TR 1295-2
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
August 2005
ICS 23.040.01
English Version
Structural design of buried pipelines under various conditions of
loading - Part 2: Summary of nationally established methods of
design

Calcul de résistance mécanique des canalisations Statische Berechnung von erdverlegten Rohrleitungen

enterrées sous diverses conditions de charge - Partie 2: unter verschiedenen Belastungsbedingungen - Teil 2:

Résumé des méthodes nationales de dimensionnement Zusammenstellung national eingeführter

Berechnungsverfahren

This Technical Report was approved by CEN on 28 February 2005. It has been drawn up by the Technical Committee CEN/TC 165.

CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,

Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,

Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 1295-2:2005: E

worldwide for CEN national Members.
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CEN/TR 1295-2:2005 (E)
Contents

Foreword ..................................................................................................................................................................4

Introduction..............................................................................................................................................................5

1 Scope...........................................................................................................................................................6

2 Normative references.................................................................................................................................6

3 Terms and definitions.................................................................................................................................6

4 Additional details about established methods .........................................................................................6

Annex A (informative) Summary of Methods of different countries.....................................................................7

A.1 Austria.........................................................................................................................................................7

A.1.1 General remarks..........................................................................................................................................7

A.1.2 Differences between "option 1" and ÖNORM B 5012...............................................................................7

A.1.3 Principles.....................................................................................................................................................8

A.2 Belgium........................................................................................................................................................9

A.2.1 General........................................................................................................................................................9

A.2.2 Flowchart.....................................................................................................................................................9

A.2.3 Design, equations, tables and charts, symbols and abbreviations ........................................................9

A.3 Denmark.....................................................................................................................................................21

A.3.1 General......................................................................................................................................................21

A.3.2 Charges.....................................................................................................................................................24

A.3.3 Safety.........................................................................................................................................................26

A.3.4 Partial safety factors.................................................................................................................................27

A.3.5 Calculations...............................................................................................................................................27

A.4 France........................................................................................................................................................29

A.4.1 Scope.........................................................................................................................................................29

A.4.2 Original features of the method ...............................................................................................................29

A.4.3 Description................................................................................................................................................29

A.4.4 Example of calculation.............................................................................................................................37

A.5 Germany....................................................................................................................................................39

A.5.1 Introduction...............................................................................................................................................39

A.5.2 Types of soil..............................................................................................................................................39

A.5.3 Live loads..................................................................................................................................................40

A.5.4 Effects of the installation on the structural calculation .........................................................................44

A.5.5 Loading......................................................................................................................................................44

A.5.6 Load distribution.......................................................................................................................................45

A.5.7 Pressure distribution at pipe circumference ..........................................................................................50

A.5.8 Sectional forces, stresses, strains, deformations..................................................................................51

A.5.9 Dimensioning............................................................................................................................................52

A.6 Netherlands...............................................................................................................................................56

A.6.1 General......................................................................................................................................................56

A.6.2 Earth load..................................................................................................................................................56

A.6.3 Evenly distributed surface load ...............................................................................................................57

A.6.4 Traffic loads...............................................................................................................................................57

A.6.5 Heavy transport.........................................................................................................................................57

A.6.6 Loads form external and internal water pressure ..................................................................................58

A.6.7 Thermal loading........................................................................................................................................58

A.6.8 Moments and normal forces ....................................................................................................................59

A.6.9 Calculation model for a concrete pipe ....................................................................................................62

A.6.10 Recommended design values..................................................................................................................69

A.7 Norway.......................................................................................................................................................73

A.7.1 Types of loads...........................................................................................................................................73

A.7.2 Soil loads...................................................................................................................................................73

A.7.3 Self weight of pipe....................................................................................................................................73

A.7.4 Weight of water.........................................................................................................................................74

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A.7.5 Traffic load.................................................................................................................................................74

A.7.6 Load distribution and bedding reaction..................................................................................................74

A.7.7 Safety analysis..........................................................................................................................................74

A.7.8 Structural design.......................................................................................................................................74

A.8 Sweden......................................................................................................................................................75

A.8.1 Design of buried plastic pipes .................................................................................................................75

A.8.2 Calculation method for rigid pipes ..........................................................................................................83

A.9 United Kingdom........................................................................................................................................86

A.9.1 General description..................................................................................................................................86

A.9.2 Calculation procedures............................................................................................................................86

A.9.3 Rigid pipes.................................................................................................................................................87

A.9.4 Semi-rigid pipes........................................................................................................................................90

A.9.5 Flexible pipes............................................................................................................................................93

Bibliography.........................................................................................................................................................110

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SIST-TP CEN/TR 1295-2:2005
CEN/TR 1295-2:2005 (E)
Foreword

This Technical Report (CEN/TR 1295-2:2005) has been prepared by Technical Committee CEN/TC 165

“Wastewater engineering”, the secretariat of which is held by DIN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.

CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This Technical Report was prepared by a Joint Working Group (JWG 1) of Technical Committees TC 164, Water

supply, the secretariat of which is held by AFNOR, and TC 165, Waste water engineering, the secretariat of which

is held by DIN.

This Technical Report is intended for use in conjunction with the series of product standards covering pipes of

various materials for the water industry.

This Technical Report includes an Informative Annex A in which are included additional details about the nationally

established methods of design declared, submitted by and used in member countries, and collated by the Joint

Working Group.
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CEN/TR 1295-2:2005 (E)
Introduction

The structural design of buried pipelines constitutes a wide ranging and complex field of engineering, which has

been the subject of extensive study and research, in many countries over a period of very many years.

Whilst many common features exist between the design methods which have been developed and established in

the various member countries of CEN, there are also differences reflecting such matters as geological and climatic

variations, as well as different installation and working practices.

In view of these differences, and of the time required to develop a common design method which would fully reflect

the various considerations identified in particular national methods, a two stage approach has been adopted for the

development of this document.

In accordance with this two stage approach, the Joint Working Group, at its initial meeting, resolved "first to

produce a document giving guidance on the application of nationally established methods of structural design of

buried pipelines under various conditions of loading, whilst working towards a common method of structural

design". This document represents the full implementation of the first part of that resolution.

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CEN/TR 1295-2:2005 (E)
1 Scope

In addition to EN 1295-1, this Technical Report gives additional guidance when compared with EN 1295-1 on the

application of the nationally established methods of design declared by and used in CEN member countries at the

time of preparation of this document (see informative Annex A).

This Technical Report is an important source of design expertise, but it cannot include all possible special cases, in

which extensions or restrictions to the basic design methods may apply.

Since in practice precise details of types of soil and installation conditions are not always available at the design

stage, the choice of design assumptions is left to the judgement of the engineer. In this connection the document

can only provide general indications and advice.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references,

only the edition cited applies. For undated references, the latest edition of the referenced document (including any

amendments) applies.

EN 1295-1, Structural design of buried pipelines under various conditions of loading — Part 1: General

requirements
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1295-1 apply.

4 Additional details about established methods

Annex A gives for several countries details about the established methods of design declared, submitted by and

used in member countries.
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CEN/TR 1295-2:2005 (E)
Annex A
(informative)
Summary of Methods of different countries
A.1 Austria
A.1.1 General remarks

The Austrian Standard Őnorm B 5012:2005 is based on the "option 1" contained in CEN/TR 1295-3.

This "option 1" had been prepared by the TG1 of the CEN/TC164-165/JWG1 as a result of thorough study of the

subject and long-lasting consultations carried out from 1992 onwards.

Although the design method described in "option 1" was mainly based on two recognised and well-tested "national

methods", the German ATV-DVWK-A 127 and the (former) Austrian ÖNORM B 5012-1 and – 2, some new

assumptions had to be incorporated in the re-drafted "option 1" in order to consider the most recent experience

gained in this domain.

Therafter, it was of course also necessary to prove the correctness of the newly made assumptions by means of

comprehensive field testing. This particular kind of testing was done during the period from 2000 to 2004. The tests

results obtained were already incorporated in the ÖNORM B 5012 a revision of the former parts 1 and 2 of this

standard.

Therefore the ÖNORM B 5012:2005 represents a calculation method which is based on the most recent

experience in this field, but it still complies with the calculation principles elaborated by "JWG 1" regarding the

"option 1" of CEN/TR 1295-3.
A.1.2 Differences between "option 1" and ÖNORM B 5012
The ÖNORM B 5012 differs in the following points from "option 1":
1) Two different applications of ÖNORM B 5012 enable to make
i) calculations for pipe design and
ii) back-calculations of failure situations

For the pipe design the soil moduli proposed in "option 1" (Table 4) shall be reduced by the factor 0,5, whereas for

back-calculations the unchanged soil moduli from "option 1" should be used.
The purpose for this distinction is the following:

The results of calculations for the pipe design should be close to the 95 % fractile of the scattering design values,

like deflection, stress or strain. Then the required safety or failure probability is assured by using the safety factors

proposed in ÖNORM B 5012.

However, for back-calculations of failure situations the calculation results should be as close as possible to the

mean value of the measured values.

2) Factor f is changed in ÖNORM B 5012 in comparison to "option 1" ( compare equation 23 in "option 1"

R,GW
and ÖNORM B 5012).

3) The soil pressure ratios K and K are partly changed (compare Table 11 in "option 1" and ÖNORM B

1 2
5012).
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4) The recommended support angles α are partly changed (compare Table 13 in "option 1" and ÖNORM B

5012).

5) In ÖNORM B 5012 the horizontal bedding stiffness S and factor ζ is calculated in a clearer and easier

way than in "option 1" (compare 8.3.2 in "option 1" and ÖNORM B 5012).

6) The estimated values of relative initial ovalization δ in "option 1" are reduced in ÖNORM B 5012 by the

v,io

factor 0,5 (compare Tables 19 and 20 in "option 1" with Table 18 and 19 in ÖNORM B 5012).

7) In ÖNORM B 5012 it is proposed to use the theory 2 order calculation more consequently than in "option

1" (in ÖNORM for flexible pipes with deflections greater than 1 % in comparison to 5 % in "option 1").

A.1.3 Principles

Like "option 1", the ATV-DVWK-A 127 and the ÖNORM model the calculation system of ÖNORM B 5012 is based

on the model of the embedded circular or non circular ring. The pipe-soil interaction is taken into account by the

following interpretations:

1) In vertical direction: Using the shear-stiff beam model above the pipe for the calculation of the vertical

loading due to the earth weight and uniformly distributed surcharge;

2) In horizontal direction: Using the compatibility condition of the horizontal pipe and soil movements taking

into account all loads considered in the calculation (e.g. for the calculation of the horizontal bedding

reaction pressures).

Further descriptions of details about the principles and the calculation method are stated in CEN/TR 1295-3.

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SIST-TP CEN/TR 1295-2:2005
CEN/TR 1295-2:2005 (E)
A.2 Belgium
A.2.1 General

Calculation procedure of the ISO 2785: Directives for selection of asbestos-cement pipes subject to external loads

with or without internal pressure.
A.2.2 Flowchart
A.2.3 Design, equations, tables and charts, symbols and abbreviations
A.2.3.1 Symbols and abbreviations
A width of uniform surcharge of small extent, in metres;
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SIST-TP CEN/TR 1295-2:2005
CEN/TR 1295-2:2005 (E)
a distance between two wheels on a single axle of a truck, in metres;
B width of trench at the crown of the pipe, in metres;

B’ distance of the spring-line of a pipe from the wall of the trench in which it is buried, in metres;

h distance between two wheels of two different axles of a truck, in metres;

c diagonal distance between two wheels of two different axles of a truck, in metres;

C.C earth-load coefficient for a trench with vertical walls;
C load coefficient for superimposed concentrated moving loads;
C load coefficient for uniform surcharges of small extent;
C load coefficient for uniform surcharges of large extent;
C , C , C , C coefficients of vertical deformation of pipe;
v d1 v2 v3
C , C coefficients of horizontal deformation of pipe;
h2 h3
d nominal or internal diameter of pipe, in millimetres;
D external diameter of pipe, in metres;
e base of natural logarithms;
E modulus of elasticity, in Newtons per square millimetre;
E modulus of elasticity of pipe, in Newtons per square millimetre;
E modulus of compression of soil, in Newtons per square millimetre;

E modulus of elasticity of road construction material, in Newtons per square millimetre;

E , E , E , E moduli of compression of soil and backfill in various zones of the trench, in Newton per square

1 2 3 4
millimetre;
H, H , H heights of earth cover of a pipe, in metres;
1 2
H equivalent height of earth cover a pipe laid under a paved road, in metres;
HT heavy truck;

I modulus of inertia of the wall of the pipe per unit length, in cubic millimetres;

k factor of ring-bending moment;

k , k , k , k factors of ring-bending moments due to vertical and horizontal loads, horizontal reaction pressure

v1 h1 hp w
and water-load respectively;
K , K coefficients of lateral earth pressure;
1 2
L length of uniform surcharge of small extent, in metres;
LT light truck;
m, m , m , m concentration factors of vertical earth pressure over the pipe;
0 1 m
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CEN/TR 1295-2:2005 (E)

M ultimate ring-bending moment of pipe when tested in accordance with ISO 881 or ISO 160, in

Kilonewton metre per metre;

M maximum ring-bending moment in the wall of a buried, Kilonewton metre per metre;

M the ring-bending moment that will fracture the pipe when combined with an internal hydraulic pressure

p1;
M the ultimate ring-bending moment when no internal pressure affects the pipe;
n concentration factor of lateral earth pressure on the sides of the pipe;
P intensity of distributed load, in kilonewtons per square metre;
P pipe projection ratio;
P hydraulic working pressure, in Megapascal;

P the internal hydraulic pressure that will fracture the pipe when combined with a ring-bending moment

M ;

P the internal hydraulic pressure that will burst a pipe which is not exposed to any external load;

P crushing load of a pipe when tested in accordance with ISO 881, in kilonewtons per 200 or 300

millimetre lengths of pipe;
P maximum wheel load of a truck, in kilonewtons;

P vertical pressure on a pipe due to moving concentrated surcharge, in kilonewtons per square metre;

vertical pressure on a pipe due to moving distributed surcharge, in kilonewtons per square metre;

q , q , q vertical earth pressure on the pipe, in kilonewtons per square metre;
v v1 v2

q total vertical pressure due to earth and moving load on the pipe, in kilonewtons per square metre;

q , q , q horizontal earth pressure on the pipe, in kilonewtons per square metre;

h h1 h2

q , q , q horizontal soil reaction pressure on the pipe, in kilonewtons per square metre;

hp hp1 hp2
r mean radius of pipe, in metres;
s wall thickness of pipe, in metres;
s stiffness of pipe, in Newtons per square metre;

S horizontal stiffness of soil backfill in the zone of the pipe, in Newtons per square millimetre;

S vertical stiffness of pipe bedding, in Newtons per square millimetre;
t , t thickness of layers in a road structure, in metres;
1 2
V , V stiffness ratio;
s s1
V pipe-soil system stiffness;
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w, w , w unit weight of backfill soil, in kilonewtons per cubic metre;
1 2

W crushing load per unit length of pipe when tested in accordance with ISO 160, in kilonewtons per

metre;
x , x , x auxiliary parameter defined in the text;
1 2 3
α half the bedding angle of pipe;
β slope of the wall of the trench;
γ specific weight of water in kilonewtons per cubic metre;
δ deformation coefficient;
ξ correction factor;

η reduction factor of the resistance of the pipe to external load due to the action of internal pressure;

η reduction factor of the resistance of the pipe to internal pressure due to the action of external load;

ν safety factor against crushing of a pipe loaded externally without internal pressure;

ν safety factor against bursting of a pipe when a ring-bending moment is applied together with a internal

hydraulic pressure;
ρ angle of internal friction of backfill soil;
ρ‘ angle of friction between the backfill soil and the wall of the trench;
ø impact factor.
A.2.3.2 Required basic data
 D, s, r, E pipe parameters ;
 B, H trench/embankment conditions;
 K , K coefficients of lateral earth pressure, out of Table A.2;
1 2
 ρ angle of internal friction, out of soil investigation or Table A.1;
 p projection ratio;
 E - E - E - E soil conditions, out of soil investigation or Table A.1.
1 2 3 4
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CEN/TR 1295-2:2005 (E)
Table A.1 — Properties of soils for calculating earth-load
Group a Unit, ρ b
Types of soil Moduli of compression E at following
of soil
Proctor standard densities (%) achieved
weight, ω degrees
by self-consolidation compaction
kN/m
N/mm
85 90 92 95 97 100
1 Non-cohesive 20 35 2,5 6 9 16 23 40
2 Slightly cohesive 20 30 1,2 3 4 8 11 20
3 Mixed cohesive 20 25 0,8 2 3 5 8 14
4 Cohesive 20 20 0,6 1,5 2 4 6 10
The four types of soil are:
non-cohesive: gravel, sand;
slightly cohesive: binding non-uniform sand or gravel;
mixed cohesive: rock flour, weathered rock soils, clayey sand;
cohesive: clay, silt, loam.

The moduli of compression E of the soils are measured by applying the CBR (California Bearing Ratio)

method using a round plate of an area of 700 cm .
Table A.2 — Coefficients of lateral earth pressures
Group of soil K K
1 2
1 0,5 0,4
2 0,5 0,3
3 0,5 0,2
4 0,5 0,1
K and K shall always be considered simultaneously.
1 2
A.2.3.3 Selection of type of pipe laying
Three types of pipe laying are defined, see Figures A.1, A.2 and A.3.
key
1 Narrow trenches
2 Wide trench
3 Embankment conditions: positive projection

NOTE Type 1 covers trenches, wide trenches and positive projection embankment conditions.

Figure A.1 — Type 1 of laying
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SIST-TP CEN/TR 1295-2:2005
CEN/TR 1295-2:2005 (E)
NOTE Type 2 covers negative projection conditions.
Figure A.2 — Type 2 of pipe laying
NOTE Type 3, two or more pipelines in a single trench.
Figure A.3 — Type 3 of pipe laying
A.2.3.4 Determination of the pipe soil system parameters
a) Stiffness of the pipe S
D − s
Ep (s)
r =
S =
12 r
with
b) Vertical stiffness of the bedding S
S =
Horizontal stiffness of the bedding S
c) sh
S = 0,6ξ E
sh 2
 
1,662 + 0,639 −1
 
 
withξ =
B  B  E
   
−1 + 1,662 − 0,361 −1
   
 
D D E
   
  3
d) Pipe-soil fitness V (see Figure A.4)
V =
The distribution of the vertical earth pressure and reaction.
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...

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