CEN/TR 1295-3:2007

Structural design of buried pipelines under various conditions of loading - Part 3: Common method

This document specifies calculation methods for the structural design of water supply pipelines, drains and sewers, and other water industry pipelines, whether operating at atmospheric, greater or lesser pressure.
It applies for the structural design of buried piping systems, made from all materials used for the conveyance of fluids under pressure or gravity conditions.
Pipes to be designed for installations in abnormal or unusual conditions, e.g. in quick soils or a marine sea bed, are not covered by this document, it may require special engineering.
The design of very large diameter pipe installations may require considerations to be given to other additional parameters, e.g. the homogeneity of the surrounding soil.
The design method is intended to be used for pipes operating at different temperatures provided that the corresponding temperature re-rating factors for the relevant pipe properties are used as specified in the referring standard(s). Nevertheless, high services temperatures may require an additional analysis of the longitudinal stresses and strains and/or a special design of the joints.

Statische Berechnung von erdverlegten Rohrleitungen unter verschiedenen Belastungsbedingungen - Teil 3: Einheitliches Berechnungsverfahren

Calcul de résistance mécanique des canalisations enterrées sous diverses conditions de charge - Partie 3: Méthode commune

Le présent document spécifie les méthodes de calcul pour le calcul de résistance mécanique des conduites d'alimentation en eau, des canalisations d'évacuation et d'assainissement et autres canalisations de l'industrie de l'eau, fonctionnant soit à la pression atmosphérique, soit à des pressions supérieures ou inférieures.
Il s'applique au calcul de résistance mécanique des systèmes de canalisations enterrées, fabriqués à partir de tous les matériaux utilisés pour l'acheminement des fluides, sous pression ou dans des conditions gravitaires.
Les tuyaux devant être calculés pour des installations dans des conditions anormales ou inhabituelles, par exemple dans des sols boulants ou sous la mer, ne sont pas couverts par le présent document et l'utilisation d'une étude spéciale peut s'avérer indispensable.
Le calcul d'installations de tuyaux de très gros diamètres peut exiger la prise en compte d'autres paramètres additionnels, comme par exemple l'homogénéité du sol environnant.
La méthode de conception est censée être employée pour des tuyaux exploités à différentes températures à condition que les coefficients correspondants de réévaluation de la température pour les propriétés concernées du tuyau soient utilisés de la manière spécifiée dans la (les) norme(s) de référence. Néanmoins, les températures de service élevées peuvent exiger une analyse complémentaire des contraintes et des déformations longitudinales et/ou une conception spéciale des assemblages.

Projektiranje vkopanih cevovodov pri različnih pogojih obtežb - 3. del: Skupna metoda

General Information

• Status: Published
• Publication Date: 24-Jul-2007
• ICS: 23.040.01 - Pipeline components and pipelines in general
• Technical Committee: CEN/TC 165 - Waste water engineering
• Drafting Committee: CEN/TC 165/WG 12 - Structural design of buried pipelines
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 25-Jul-2007
• Completion Date: 25-Jul-2007
• Ref Project: SIST-TP CEN/TR 1295-3:2007 - Structural design of buried pipelines under various conditions of loading - Part 3: Common method

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2007
3URMHNWLUDQMHYNRSDQLKFHYRYRGRYSULUD]OLþQLKSRJRMLKREWHåEGHO6NXSQD
PHWRGD
Structural design of buried pipelines under various conditions of loading - Part 3:
Common method
Statische Berechnung von erdverlegten Rohrleitungen unter verschiedenen
Belastungsbedingungen - Teil 3: Einheitliches Berechnungsverfahren
Calcul de résistance mécanique des canalisations enterrées sous diverses conditions de
charge - Partie 3: Méthode commune
Ta slovenski standard je istoveten z: CEN/TR 1295-3:2007
ICS:
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 1295-3
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
July 2007
ICS 23.040.01
English Version
Structural design of buried pipelines under various conditions of
loading - Part 3: Common method
Calcul de résistance mécanique des canalisations Statische Berechnung von erdverlegten Rohrleitungen
enterrées sous diverses conditions de charge - Partie 3: unter verschiedenen Belastungsbedingungen - Teil 3:
Méthode commune Einheitliches Berechnungsverfahren
This Technical Report was approved by CEN on 11 July 2005. It has been drawn up by the Technical Committee CEN/TC 165.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, 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
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 1295-3:2007: E
worldwide for CEN national Members.

Contents Page
Foreword.6
Introduction .7
1 Scope .9
2 References.9
3 Structural design issues .9
3.1 Soils .9
3.2 Pipe materials.11
3.3 Types of loading .11
3.3.1 Soil load .11
3.3.2 Traffic load.11
3.3.3 Groundwater.11
3.3.4 Installation loads.11
3.3.5 Internal pressure.11
3.3.6 Pipes own weight.12
3.3.7 Weight of fluid.12
3.3.8 Subsidence (differential settlement).12
3.3.9 Temperature differences.12
3.3.10 Landslide .12
3.3.11 Loading by earthquake .12
4 Principles used in Annex A (Option 1) and Annex B (Option 2) .13
4.1 General.13
4.2 Principles used in Annex A (Option 1) .13
4.2.1 Introduction.13
4.2.2 Information on the content of Annex A (Option 1).13
4.3 Principles used in Annex B (Option 2) .16
5 Synopsis .18
Annex A Structural design of buried pipelines - Option 1.21
A.1 General.21
A.2 Terms and definitions .21
A.3 Symbols .25
A.4 Principle.31
A.5 Installation conditions.33
A.5.1 Geometric parameters.33
A.5.2 Construction procedures.33
A.5.3 Influencing parameters .34
A.5.4 Selection of embedment type.35
A.6 Initial loads .39
A.6.1 Soil load .39
A.6.2 Surface loads .41
A.6.3 Traffic loads.43
A.6.4 Seismic actions.47
A.6.5 Other loads .48
A.7 Soil parameters.48
A.7.1 Soil groups .48
A.7.2 Soil properties.48
A.7.3 Soil pressure ratio .54
A.8 Load distributions.55
A.8.1 General.55
A.8.2 Distribution in circumferential direction.56
A.8.3 Load concentration factors .62
A.9 Loads acting on the pipe .68
A.9.1 General .68
A.9.2 Vertical direction .69
A.9.3 Horizontal direction.70
A.10 Internal pressure .75
A.10.1 General .75
A.10.2 Internal working pressure.75
A.10.3 Internal surge pressure.75
A.11 Pipe deflection .76
A.11.1 General .76
A.11.2 Vertical deflection.76
A.11.3 Horizontal deflection .79
A.12 Analysis of bending moments, normal forces, stresses and strains .80
A.12.1 General .80
A.12.2 Bending moments and normal forces.80
A.12.3 Stresses and/or strains.85
A.13 Longitudinal effects .95
A.14 Stability analysis (only required for flexible pipes) .95
A.14.1 Imperfections .95
A.14.2 Stability analysis with buckling and snap through loads .96
A.15 Calculated factors of safety from the design procedure and analysis.100
A.15.1 General .100
A.15.2 Circumferential direction.100
A.15.3 Longitudinal direction.103
A.16 Minimum factors of safety and failure probability .103
A.16.1 Principles.103
A.16.2 Safety factors against load bearing failure.103
A.16.3 Safety against inadmissible large deflections .104
A.16.4 Safety against failure in case of not predominantly static load .104
Annex AA Classification of soils .105
Annex AB Factors of safety and failure probability.106
Annex AC Soil mechanics background on soil moduli.107
Annex AD General remarks on stability analyses for buried pipes .110
Annex AE Finite element analysis .112
Annex AF Detailed notes relative to longitudinal effects.113
Annex AG Flowchart and worked examples.114
Annex B Structural design of buried pipelines - Option 2 .128
B.1 General .128
B.2 Terms and definitions .128
B.3 Symbols.131
B.4 Principle.134
B.5 Pipe parameters.135
B.5.1 Dimensions .135
B.5.2 Elastic properties .135
B.5.3 Pipe ring stiffness .135
B.5.4 Pipe characteristics figures .136
B.6 Installation conditions and related calculation parameters.136
B.6.1 Introduction.136
B.6.2 Soil classification .137
B.6.3 Embedments and beddings.137
B.6.4 Compaction.138
B.6.5 Calculation parameters.140
B.7 Stiffness criterion .143
B.8 Loadings .143
B.8.1 General.143
B.8.2 Soil vertical pressure due to fill .144
B.8.3 Vertical pressure due to service loads.147
B.8.4 Total vertical pressure p (due to fill and service loads) .149
v
B.8.5 Horizontal pressure p due to fill and service loads .149
h
B.8.6 Pressure due to external water pressure p .149
we
B.8.7 Action due to self weight .149
B.8.8 Force due to water weight .149
B.9 Load and interaction pressure distributions .149
B.9.1 General.149
B.9.2 Loads distribution.150
B.10 Buckling.151
B.11 Ring deflection.152
B.12 Bending moments, axial forces, stresses and strains.153
B.12.1 Bending moments.153
B.12.2 Axial forces.154
B.12.3 Strains.154
B.12.4 Stresses .154
B.13 Verification of safety in use .155
B.13.1 Definition of the limit states.155
B.13.2 Verification with respect to ultimate limit state .156
B.13.3 Verification with respect to serviceability limit states.158
B.13.4 Verification with respect to fatigue.159
B.13.5 Verification for pressure pipes.159
B.14 Summary of design procedures and relevant verifications .161
B.14.1 Choice of parameters used in the design method .161
B.14.2 Calculation of the actions .162
B.14.3 Calculation of the loads and deflections.163
B.15 Analysis of longitudinal effects.164
B.16 Analysis of seismic action.164
Annex BA Classification of soils.165
Annex BB Factors of safety and failure probability.166
Annex BC Background on soil moduli .167
Annex BD Rigid, semi-rigid and flexible pipes — A proposal for a definition of ranges of system
behaviour.168
Annex BE Background of the Marston method.175
Annex BF Longitudinal effects — Notes of B.15 .183
Annex BG Worked examples.184
Annex C Classification of soils .190
Annex D Factors of safety and failure probability.193
D.1 Rudiments of the theory of probabilistic reliability.193
D.2 Analysis of reliability of buried piping systems.196
D.3 Scatter of parameters.196
D.4 Results of the analysis.196
Annex E Longitudinal effects .197
E.1 Longitudinal effects.197
E.2 Failure behaviour due to longitudinal effects.197
E.3 Failure modes.197
E.3.1 General.197
E.3.2 Pipeline failure .198
E.3.3 Joint failure.198
E.3.4 Gradient loss.198
E.4 Longitudinal effects .198
E.4.1 Genral .198
E.4.2 Discontinuous support .199
E.4.3 Directional changes .199
E.4.4 Pressure loading .199
E.4.5 Temperature differences.199
E.4.6 Settlements and subsidence.200
E.4.7 Transition zones .201
Annex F Detailed notes relative to longitudinal effects (according to A.13 and B.15).202
Bibliography.205

Foreword
This document (CEN/TR 1295-3:2007) has been prepared by Technical Committee CEN/TC 165
“Wastewater engineering”, the secretariat of which is held by DIN.
This document has been prepared by a joint working group of the Technical Committee CEN/TC 165
“Wastewater engineering” the secretariat of which is held by DIN and the Technical Committee CEN/TC 164
"Water supply", the secretariat of which is held by AFNOR.
This document is a composition of two options for the structural design of buried pipelines, including the
annexes of each option, which have been combined in one single document. The document includes therefore
the followind Annexes:
Annex A , Structural design of buried pipelines – option 1, including the Annexes to option 1 (Annex AA to
Annex AG);
Annex B, Structural design of buried pipelines – option 2, including the Annexes to option 2 (Annex BA to
Annex BG);
Annex C , Classification of soils;
Annex D, Factors of safety and failure probability;
Annex E, Longitudinal effects;
Annex F, Detailed notes relative to longitudinal effects.
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.

Introduction
The history
In the mid-eighties the European Commission gave CEN an Order Voucher to develop a so-called "Common
Structural Design Method for Buried Pipes" and the work was allocated jointly to CEN/TC 164 (Water supply)
and CEN/TC 165 (Waste water engineering). To avoid duplication of work a Joint Working Group (CEN/TC
164/165 JWG1) was created in 1990. As a first step the group produced EN 1295-1, which was published in
July 1997 and is a general part describing the "principles and input parameters" for structural design of buried
pipelines and gives guidance on the application of these principles to nationally established methods of
design. Reference was made to those methods and sources of information on them are given.
The second step was to produce CEN/TR 1295-2, which was published in August 2005 and describes
national or regional methods JWG1 continued its work with the aim of developing a single method for the
structural design of buried pipes for water and wastewater, planned as EN 1295-3 (WI 00165155).
NOTE The work on WI 00165155 concentrated on pipes, not the piping system involving all components.
In 1992 JWG1 decided to give the work on a "Common Method" to a small group of experts (TG1). By this
means it was thought to create optimal conditions for dealing with such a difficult task. The task, however,
proved to be much more difficult than had been expected, because different design cultures exist throughout
Europe. After much debate and analysis JWG1 finally arrived at a situation where two options were provided
for internal TC enquiry, which closed in May 2002. The comments received from CEN members varied widely
from strongly against one or both options, to very much in favour of one of them.
Faced with this result, CEN/TC 164 and CEN/TC 165 decided that the two options should not go to CEN
enquiry, even though they would have been presented in an informative annex of the document. (A note
would have been included in the short normative text, stating that a single "Common Method" could not yet be
agreed but, during the next five years, the two options should be checked and reported upon by European
experts working in this field. In the meantime, CEN/TC 164 and CEN/TC 165 continued its efforts to develop
the "Common Method".
Current European practices
The "designer" is responsible for structural design in accordance with EN 1610,
JWG1 collated the national approaches to the structural design of buried pipelines in the countries of the CEN
members who were participating in the work. The outcome was EN 1295-1, which facilitates a common basis
of relevant requirements for application to nationally established methods of design. Although widely varying
in their approach, these design cultures have been shown to provide continuity of acceptable design practice
throughout Europe.
Later, CEN/TC 164 and CEN/TC 165 requested all CEN members to submit their current nationally
established method for such structural designs. The collated outcome is given in CEN/TR 1295-2.
A common factor in all of the nationally established methods is that the parameters for pipe material and
surface loads (i.e. mainly traffic loads) are well known and (depending on national requirements for the
manufacturers' and any third-party quality control) in several countries even quality-controlled. On the other
hand, only a few nationally established methods demand that soil parameters are obtained from each
prospective construction site and not many of them prescribe test methods for soil parameters.
Furthermore, the multitude of calculation methods employed throughout Europe, now collated in
CEN/TR 1295-2, use different soil parameters and these cannot be "transferred" from one calculation method
to another.
Whilst pipe material parameters are easily available from product standards and/or pipe manufacturers, the
definition of soil parameters is the responsibility of the prospective pipeline owner or his designer. This
possibly explains why, in many European countries, the traditional practice continues whereby detailed
structural analysis of buried pipelines for water and wastewater systems is not carried out. The pipe
manufacturers often provide information about the loading that the chosen pipe will withstand and this can
often avoid investigating actual soil conditions.
If the structural design of a buried pipeline for a water or wastewater system is demanded, many construction
companies and designers approach the pipe manufacturer, who will usually have the necessary expertise. But
here too the same problems can occur, for the pipe material parameters are usually clearly defined (and a
quality control system often established), whilst the soil parameters are uncertain. Only in a very few cases is
there a quality control system for the earthworks at the construction site.
It is fundamental that, for a "Common Method" to apply throughout Europe, agreement shall first be reached
on the definitions and test methods for soil parameters and a certain quality control system for the earthworks
on site (see Clause 3), not withstanding that specific pipe material features are more easily recognized and
taken into account.
The results obtained so far from the work of CEN/TC 164/165 JWG1 are shown in Clause 4. In 2003 CEN/TC
164 and CEN/TC 165 accepted a recommendation from JWG1 that the two structural design options should
be published as a CEN Technical Report (CEN/TR) and work on a European Standard terminated, because
there was no prospect of the group reaching agreement on a "Common Method" and the human and financial
resources needed to continue were, in any case, no longer available.
CEN/TC 164 and CEN/TC 165 accepted that it would be a pity to lose all the previous work, which should be
made available to designers and the general public. The outcome is this document and it is hoped that the two
options will provide a basis for continued debate and investigation.
The "Common Method"
Any future proposal for a new work item for the development of a European Standard for a "Common Method"
for the structural design of buried pipelines would have to be approved by both CEN/TC 164 and CEN/TC
165, taking into account experience gained with the two options detailed in this document. There would also
have to be a reasonable certainty of agreement being reached on a "Common Method" within the three-year
limit for developing European Standards.
NOTE 1 Each structural analyst remains responsible for the choice of the calculation or design method.
NOTE 2 Subject to the requirements of the EU Procurement Directives as to the use of European Standards in public
sector contracts, any future "Common Method" would be applied on the responsibility of the designer.
NOTE 3 One of the aims of a "Common Method" was to facilitate a general comparison between different pipeline
materials and types for certain cases. It would also have been applicable to the general pressure classification of all pipes,
as requested in EN 805:2000. For the time being, it would help if product standards indicated a method for that purpose.
Concluding remarks
This document describes the outcome of the work aimed at a "Common Method". Although the resulting two
options could not be distilled into a single one, they are believed to be valid for many loading conditions for
buried pipes. A survey of differences between option 1 and option 2 is given in Table 1. The report does not
reflect the comments received from CEN members on the two options and the answers given by the principal
advocates of each one.
CEN/TC 164 and CEN/TC 165 are aware that they did not fully succeed in agreeing a single "Common
Method", but the development of two methods still represents considerable progress in underground pipeline
applications.
The two options should provide a good basis for future discussions about a single method and time will tell
which seems the more feasible. In the meantime it is hoped that they will both be used and experience with
them documented. Experts are invited to send experiences or questions to the secretariat of CEN/TC 165.
1 Scope
This document specifies calculation methods for the structural design of water supply pipelines, drains and
sewers, and other water industry pipelines, whether operating at atmospheric, greater or lesser pressure.
It applies for the structural design of buried piping systems, made from all materials used for the conveyance
of fluids under pressure or gravity conditions.
Pipes to be designed for installations in abnormal or unusual conditions, e.g. in quick soils or a marine sea
bed, are not covered by this document, it may require special engineering.
The design of very large diameter pipe installations may require considerations to be given to other additional
parameters, e.g. the homogeneity of the surrounding soil.
The design method is intended to be used for pipes operating at different temperatures provided that the
corresponding temperature re-rating factors for the relevant pipe properties are used as specified in the
referring standard(s). Nevertheless, high services temperatures may require an additional analysis of the
longitudinal stresses and strains and/or a special design of the joints.
2 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 amendments) applies.
EN 1610, Construction and testing of drains and sewers
EN 1991-2, Eurocode 1 – Actions on structures — Part 2: Traffic loads on bridges
3 Structural design issues
3.1 Soils
Soil is the load-carrying, load distributing and load transmitting structure. Different types of soils may be used
for the bedding and embedding of the pipe and the main backfill of the trench.
Soil has also many parameters – as pipe materials – which have to be considered for structural design of
earth-buried pipelines. At least the following parameters need to be taken into consideration:
 relative density (Proctor density) D ;
pr
 soil density;
 friction angle;
 soil modulus.
The soil parameters vary depending on the type of soil, its degree of compaction and the presence of
groundwater. Option 1 and 2 use different soil moduli (Option 1: Oedometer; Option 2: Pressiometer).
Oedometer moduli can be measured in laboratory or by any on site measurement, where the relation to the
Oedometer-modulus is known (e.g. load plate test); specifically in case of dispute these decisive soil
parameters can be checked to clarify the guilty party for a damage.
Pressiometer-E-moduli can be measured on site only. Beside the principal difference of the Oedometer/
Pressiometer moduli is the fact that:
 CEN/TR 1295-3, Option 1 states, that the soil modulus is dependent on the vertical pressure and
consequently also on the depth of the considered point in the trench. The deeper the considered point in
the trench, the higher the Oedometer-E-modules;
 CEN/TR 1295-3, Option 2 states for Pressiometer modulus, that it is independent of the depth, because
the Pressiometer-modulus is measured in the depth of the considered point.
Experts for geotechnics have developed several European or national standards for test methods and
standards for the classification of soils; the latter shows a wide range of 20 (sometimes 30) soil classes.
For the purpose CEN/TR 1295-3, Options 1 and 2, only seven soil classes are sufficient in order to distinguish
between all types of soil. A detailed and formal description is given in the annexes to this document. The
seven classes are:
 Class 1: pea gravel is normally used only for bedding and embedding; almost “self-compacting”; either
from gravel pits or consisting of reinforced concrete debris;
 Class 2: sand or gravel, which are the best materials for bedding and embedding next to Class 1 but the
best material for main backfill;
 Class 3: silty sand or gravel is not easy to be used for bedding and embedding but a good material for
main backfill;
 Class 4: sandy clay may be used for bedding, embedding and main backfill only in exceptional cases;
 Class 5: clay may be used for bedding, embedding and main backfill, after severe consideration only in
exceptional cases;
 Class 6: organic clay may be used for bedding, embedding and main backfill (off-roads) only in
exceptional cases after severe consideration;
 Class 7: organic soil shall not be used for bedding, embedding and backfill.
Option 1 specifies that for soils as well as for pipe materials, a short-term and long-term loading is to be
considered differently. In option 2 this consideration is made for the pipe material only.
In soils as well as in pipe materials, the relevant test methods for the measurement of the soil parameters are
to be determined, in order to provide for both designers and construction companies the necessary basis for
the establishment of a “third-party quality control” and a quality control system by the construction company
itself, respectively. For the quality control system of the pipe embedment by the construction company, a
dynamic plate-loading unit has shown the best and not expensive results for continuous geotechnical quality
control in each layer when backfilling.
For the third party quality control, the easiest and not expensive tool for acceptance test is a penetration test
3333333333unit (DPH), every layer of the backfilled trench can then be checked by this test tool from the top
of the trench; only if required by the road authority, additional static plate loading tests (which give only an
answer of the quality of the upper layers of the trench) may be performed.
Only in case of dispute, more severe tests (Proctor density/soil-modulus) need to be considered necessarily.
Anyhow, before a designer starts with the structural design of earth-buried pipelines, the designer should
request preliminary investigation on the construction site
 to have the possibility to classify the native soil material of the embedment and to request goetechnical
tests, if necessary. For this purpose, both a core drilling and a penetration test (DPH) approximately every
500 m are suitable. The designer can with these results decide which layers of soil in the trench can be
used for bedding / embedding / mail backfill before the tendering documentation is elaborated and that
 the designer can then provide the parameters of the “undisturbed soil in every layer” (result from the
penetration test) for the requirements of the degree of compaction in accordance with the agreement of
the road authority.
3.2 Pipe materials
Many different kinds of pipe materials are used for the production of components to construct buried pipelines
for water and waste water systems. The pipes vary in weight, load bearing capacity and ductility. Next to that
many different types of jointing methods are used with the different pipe materials.
In accordance with EN 805 and EN 476, some product standards exist, which include dimensions, as well as
material specific information needed for a structural design purpose. All product standards should be
completed in this respect.
3.3 Types of loading
Pipes buried in ground are exposed to the following recognisable types of loading:
3.3.1 Soil load
Normally considered as the weight of the soil column above the pipe and the reaction to the side and the
bottom. This weight might be increased or decreased with the shear forces exerted by the adjacent soil.
3.3.2 Traffic load
In Europe different types of axle loading exist. G
...