ISO/TR 10465-2:1999

TECHNICAL ISO/TR
REPORT 10465-2
First edition
1999-07-15
Underground installation of flexible glass-
reinforced thermosetting resin (GRP)
pipes —
Part 2:
Comparison of static calculation methods
Installation enterrée de canalisations flexibles en plastique renforcé de
fibres de verre/résine thermodurcissable (PRV) —
Partie 2: Comparaison de méthodes de calcul statique
A
Reference number
ISO/TR 10465-2:1999(E)

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ISO/TR 10465-2:1999(E)
Contents
1 Scope .1
2 Normative references .1
3 Terminology .1
4 Symbols and abbreviated terms .2
5 Soil-load distribution.6
6 Soil load.7
6.1 General.7
6.2 Initial loadings.8
6.2.1 AWWA procedure .8
6.2.2 ATV procedure .8
6.3 Long-term loading .11
6.3.1 AWWA procedure .11
6.3.2 ATV procedure .11
7 Traffic loads.11
7.1 General.11
7.2 AWWA procedure .12
7.3 ATV procedure .14
8 Deflections.16
8.1 Resulting from vertical load .16
8.1.1 AWWA procedure .16
8.1.2 ATV procedure .17
8.2 Aspects not covered by AWWA or ATV .18
8.2.1 Deflection due to weight of pipe .18
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
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© ISO
ISO/TR 10465-2:1999(E)
8.2.2 Initial ovalization. 19
8.3 Irregularities in the installation . 19
8.3.1 General . 19
8.3.2 AWWA procedure . 19
8.3.3 ATV procedure . 19
9 Circumferential bending strain. 19
9.1 AWWA procedure . 19
9.2 ATV procedure . 20
10 Buckling. 20
10.1 General . 20
10.2 AWWA procedure . 21
10.3 ATV procedure . 22
11 Internal-pressure effects. 24
11.1 General . 24
11.2 Pressure strain. 24
11.3 Combined loading . 24
11.4 Calculations based on stress. 25
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© ISO
ISO/TR 10465-2:1999(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
The main task of ISO technical committees is to prepare International Standards, but in exceptional circumstances a
technical committee may propose the publication of a Technical Report of one of the following types:
 type 1, when the required support cannot be obtained for the publication of an International Standard, despite
repeated efforts;
 type 2, when the subject is still under technical development or where for any other reason there is the future
but not immediate possibility of an agreement on an International Standard;
 type 3, when a technical committee has collected data of a different kind from that which is normally published
as an International Standard (“state of the art“, for example).
Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they
can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to be
reviewed until the data they provide are considered to be no longer valid or useful.
ISO/TR 10465-2, which is a Technical Report of type 2, was prepared by Technical Committee ISO/TC 138,
Plastics pipes, fittings and valves for the transport of fluids, Subcommittee SC 6, Reinforced plastics pipes and
fittings for all applications.
The reasons which led to the decision to publish this document in the form of a type 2 Technical Report are
explained in the introduction.
ISO/TR 10465 consists of the following parts, under the general title Underground installation of flexible glass-
reinforced thermosetting resin (GRP) pipes:
 Part 1: Installation procedures
 Part 2: Comparison of static calculation methods
 Part 3: Installation parameters and application limits
This document is not to be regarded as an International Standard. It is proposed for provisional application so that
experience may be gained on its use in practice. Comments should be sent to the secretariat of TC 138/SC 6.
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© ISO
ISO/TR 10465-2:1999(E)
Introduction
Work in ISO/TC 5/SC 6 (now ISO/TC 138) on writing standards for the use of glass-reinforced plastics (GRP) pipes
and fittings was approved at the subcommittee meeting in Oslo in 1979. An ad hoc group was established and the
responsibility for drafting various standards was later given to a Task Group (now ISO/TC 138/SC 6).
At the SC 6 meeting in London in 1980, Sweden proposed that a working group be formed to develop documents
regarding a code of practice for GRP pipes. This was approved by SC 6, and Working Group 4 (WG 4) was formed
for this purpose. Since 1982, twenty-eight WG 4 meetings have been held which have considered the following
areas:
 procedures for the underground installation of GRP pipes;
 pipe/soil interaction with pipes having different stiffness values;
 minimum design features;
 an overview of various static calculation methods.
During the work of WG 4, it became evident that unanimous agreement could not be reached within the working
group on the specific methods to be employed. Therefore WG 4 agreed that all documents should be made into a
three-part type 2 Technical Report, of which this is part 2.
Part 1 describes procedures for the underground installation of GRP pipes. It concerns particular stiffness classes
for which performance requirements have been specified in at least one product standard, but it can also be used
as a guide for the installation of pipes of other stiffness classes.
Part 2 presents a comparison of the two primary methods used internationally for static calculations on underground
GRP pipe installations.
These methods are:
a) the ATV method given in ATV-A 127, Guidelines for Static Calculations on Drainage Conduits and Pipelines;
b) the AWWA method given in AWWA's Fiberglass pipe design manual M-45.
Part 3 gives additional information, which is useful for static calculations when using an ATV-A 127 type design
system in accordance with part 2 of this Technical Report, on items such as:
 parameters for deflection calculations;
 soil parameters, strain coefficients and shape factors for flexural-strain calculations;
 soil moduli and pipe stiffnesses for buckling calculations with regard to elastic behaviour;
 parameters for rerounding and combined-loading calculations;
 the influence of traffic loads;
 the influence of sheeting;
 safety factors.
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TECHNICAL REPORT  © ISO ISO/TR 10465-2:1999(E)
Underground installation of flexible glass-reinforced thermosetting
resin (GRP) pipes —
Part 2:
Comparison of static calculation methods
1 Scope
This part of ISO/TR 10465 presents a comparison of the ATV and AWWA methods for static calculations on
underground GRP pipe installations. It is intended that this comparison will encourage the use of both procedures
for GRP pipes conforming to International Standards.
It is not the intent of this part of ISO/TR 10465 to cover all the details of the two methods. Some aspects are, of
necessity, very complex, and for a full understanding the original documents need to be studied in detail. Rather,
the intention is to give a general overview and comparison of the key elements so that the user can more easily
understand and appreciate the differences between the two procedures and their similarities.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO/TR 10465. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this part of ISO/TR 10465 are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ATV-A 127, Guidelines for static calculations on drainage conduits and pipelines (December 1988).
AWWA M-45, (1997).
Fiberglass pipe design manual M-45
ISO/TR 10465-1:1993, Underground installation of flexible glass-reinforced thermosetting resin (GRP) pipes —
Part 1: Installation procedures.
ISO/TR 10465-3:1999, Underground installation of flexible glass-reinforced thermosetting resin (GRP) pipes —
Part 3: Installation parameters and application limits.
3 Terminology
Pipeline installation terminology can vary around the world so, where such terms are used in this part of
ISO/TR 10465, they will either be described or reference will be made to part 1 or 3, where the relevant descriptions
can be found.
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© ISO
ISO/TR 10465-2:1999(E)
4 Symbols and abbreviated terms
For the purposes of this Technical Report, the following symbols apply:
NOTE This clause also contains symbols and abbreviations from parts 1 and 3 for completeness.
Symbol Unit Meaning
a — Ageing factor
f
a — Distribution factor
f
B' — Support factor
b m Trench width at spring-line
b' m Distance from trench wall to pipe (see Figure 1)
c — Reduction factor
4
c — Creep factor
f
c , c — Deformation coefficients
h v
D — Shape factor
f
D — Shape adjustment factor
g
D — Deflection lag factor
L
d m External pipe diameter
e
d mm Mean pipe diameter [(d · 1 000) – e]
m e
mm Vertical deflection
d
v
d m Maximum permissible long-term deflection
vA
d mm Vertical deflection at rupture
vR
(d /d ) % Maximum permissible relative vertical deflection
v m permissible
(d /d ) % Initial vertical deflection
v m initial
(d /d ) % Long-term (50-year) vertical deflection
v m 50
(d /d ) % Ultimate long-term vertical deflection
v m ult
2
E, E , E N/m Apparent flexural moduli of pipe wall
o t,wet
2
E', E , E , E , E , E' , E' , E N/mm Soil deformation moduli
1 2 3 4 s t s
2
E N/m Tensile hoop modulus
TH
e mm Pipe wall thickness
e — Base of natural logarithms (2,718 281 8)
F — Compaction factor
F , F kN Wheel loads
A E
FS — Safety factor
FS — Bending safety factor
b
FS — Pressure safety factor
pr
HDB — Extrapolated pressure strain at 50 years
H m Environmental depth of cover
EVD
h m Depth of cover to top of pipe
h m Height of water surface above top of pipe
w
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© ISO
ISO/TR 10465-2:1999(E)
Symbol Unit Meaning
4
I m /m Second moment of area in longitudinal direction per unit length (of
a pipe)
i — Initial ovalization
o
2
N/mm Installation factor
i
f
K* — Coefficient for bedding reaction pressure
K , K — Ratio of horizontal to vertical soil pressure in soil zones 1 and 2
1 2
K — Ratio of horizontal to vertical soil pressure in pipe-zone backfill,
3
when backfill is at top of pipe (see ISO/TR 10465-3, annex A)
k — Bedding coefficient
x
M — Sum of bending moments
2
M N/mm Constrained-soil modulus
s
m , m , m* — Moment factors
qv qh qh
N — Sum of normal forces
n — Number of blows
10
P bar Internal pressure
PN — Nominal pressure
P(x) — Probability function
P — Probability of failure
f
2
P MPa (N/mm ) Internal underpressure
v
2
P N/m Working pressure
W
2
p N/m External water pressure
a
2
p N/mm Pressure due to prismatic soil load
E
2
p N/m Pressure due to traffic load according to Boussinesq
F
2
p N/mm Soil pressure due to distributed load
o
2
p N/mm Soil pressure resulting from traffic load
v
2
q MPa (N/mm ) Permissible buckling pressure
a
2
q MPa (N/mm ) Critical buckling pressure
c
2
q MPa (N/mm ) Short-term critical buckling pressure
cs
2
q MPa (N/mm ) Critical buckling pressure under sustained load
cl
2
MPa (N/mm ) Critical buckling pressure due to water
q
cw
2
q , q N/mm Horizontal and vertical soil pressure on pipe
h v
2
q * N/mm Horizontal bedding reaction pressure
h
2
q N/mm Long-term (50-year) horizontal soil pressure
h,50
2
q N/mm Reduced long-term horizontal soil pressure
hLT
2
q N/mm Horizontal bedding reaction for pipe and contents
c*w
2
q N/mm Long-term (50-year) vertical soil pressure
v,50
2
q N/mm Reduced long-term vertical soil pressure
vLT
2
q N/mm Vertical load due to pipe and contents
vwa
R — Water buoyancy reduction factor
w
r — Rerounding factor
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© ISO
ISO/TR 10465-2:1999(E)
Symbol Unit Meaning
r , r m Wheel radii
A E
r — Rerounding coefficient
c
2
N/mm Horizontal bedding stiffness
S
Bh
2
S N/mm Vertical bedding stiffness
Bv
S — Long-term strain
b
S — Soil support combining factor
c
2
S N/mm Characteristic stress
k
2
S N/m Initial pipe stiffness
p
2
S N/m Long-term pipe stiffness
p,50
2 –6
S N/mm S ´ 8 ´ 10
R p
2 –6
S N/mm S ´ 8 ´ 10
R,50 p,50
2
s N/mm Standard deviation of strength of pipe
Res
2
s N/mm Standard deviation of strength of pipe above ground
Res,A
2
s N/mm Standard deviation of strength of pipe below ground
Res,B
2
s N/mm Standard deviation of stress in pipe
S
2
s N/mm Standard deviation of stress in pipe above ground
S,A
2
s N/mm Standard deviation of stress in pipe below ground
S,B
SPD % Standard Proctor density
V — System stiffness
RB
V — Stiffness relation
S
2
W N/m Vertical soil load on pipe
c
2
W N/m Traffic load
L
X — Safety index
y % Coefficient of variation for tensile strength
R
y % Coefficient of variation for ultimate deflection
ult
a° (degrees) Half the bedding angle (see Figure 2)
b° (degrees) Half the horizontal support angle (see Figure 2)
c— Reduction factor applied to prismatic soil load to allow for friction
c— Reduction factor applied to prismatic soil load to allow for friction
b
and taking into account trench angle (b in ATV and w in this part
of ISO/TR 10465)
c— Reduction factor applied to a uniformly distributed load to allow for
o
friction
c— Reduction factor applied to a uniformly distributed load to allow for
ob
friction and taking into account trench angle (b in ATV but w in this
part of ISO/TR 10465)
d° (degrees) Trench wall friction angle
dmm Maximum permitted long-term installed deflection
d
d% Relative vertical deflection
v
d% Relative vertical deflection due to backfilling in pipe zone
vio
d% Relative vertical deflection due to installation irregularities
viv
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© ISO
ISO/TR 10465-2:1999(E)
Symbol Unit Meaning
d% Relative vertical deflection due to soil load
vs
d% Relative vertical deflection due to weight of pipe
vw
d% Relative vertical deflection due to traffic load
W
e— Compressive strain due to vertical load
comp
e, e, e— Calculated flexural strains in pipe wall
t f
e— Maximum permissible strain due to pressure
max
e— Calculated strain in pipe wall due to internal pressure
pr
e— Flexural strain due to total vertical load
v
e— Flexural strain due to backfilling in pipe zone
vio
e— Flexural strain due to weight of pipe
vw
e— Flexural strain due to pipe contents
W
3
gMN/m Bulk density of backfill material
b
3
gMN/m Density of pipe contents
w
h, h, h, h— Safety factors
t f ff
h— Combined flexural safety factor
haf
h— Combined tensile safety factor
hat
j° (degrees) Soil internal friction angle
k, k— Reduction factor for distributed load according to silo theory when
w
trench angle (w) is 90°
k, k— Reduction factor for distributed load according to silo theory when
o ow
trench angle (w) is not 90°
l— Concentration factor in soil next to pipe
B
l— Maximum concentration factor
max
l, l, l— Concentration factors for soil above pipe
R RG max
2
mN/mm Mean value of pipe strength (resistance)
Res
2
mN/mm Mean value of strength (resistance) of pipe above ground
Res,A
2
mN/mm Mean value of strength (resistance) of pipe below ground
Res,B
2
mN/mm Mean value of stress in pipe
S
2
mN/mm Mean value of stress in pipe above ground
S,A
2
mN/mm Mean value of stress in pipe below ground
S,B
3
rMN/m Density of pipe-wall material
3
rg/cm Density
D
2
sN/mm Calculated compressive stress in pipe wall
c
2
sN/mm Calculated tensile stress in pipe wall
t
n— Poisson's ratio for soil
s
w° (degrees) Trench wall angle (see Figure 1) (designated b in ATV-A 127)
x— Correction factor for horizontal bedding
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© ISO
ISO/TR 10465-2:1999(E)
Key
1 Ground level 5 Distance from trench wall to pipe, b'
2 Water table 6 Depth of cover to top of pipe, h
3 Height of water surface above top of pipe, h 7 Trench wall angle, w
w
4 Vertical deflection, d
v
NOTE 1 The AWWA M-45 design manual uses E' in zone E .
b 2
NOTE 2 The AWWA M-45 design manual uses E' in zone E and E .
n 3 4
NOTE 3 E is the backfill above the pipe zone (E ) material.
1 2
NOTE 4 E is the embedment material to the side of the pipe.
2
NOTE 5 E is the in situ trench wall material.
3
NOTE 6 E is the in situ material underlying the pipe zone material (foundation material).
4
NOTE 7 In ATV-A 127, b is used for the trench wall angle instead of w.
Figure 1 — Symbols and terminology
5 Soil-load distribution
The assumed soil-load distributions used in ATV-A 127 and AWWA M-45, which are based on those made by
M.G. Spangler, are shown in Figure 2. The main difference between the two assumptions is that ATV-A 127
considers the active horizontal pressure, whereas AWWA M-45, like Spangler, assumes the value to be zero. In
ATV, the influence of active horizontal pressure is accounted for by using a value for K which is in the range 0,1 to
2
0,4, depending on the type of soil in the pipe zone (zone E in Figure 1).
2
Both ATV-A 127 and AWWA M-45 use vertical deflection.
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© ISO
ISO/TR 10465-2:1999(E)
When, in the ATV system, the appropriate coefficients are used to calculate horizontal deflection using Spangler’s
assumption for soil-load distribution, the same deflection is obtained as with Spangler's system provided Spangler's
E' is multiplied by 0,6 (coefficient c in ATV).
4
Related to the question of soil distribution is the influence of the modulus of passive soil resistance. ATV introduces
the term S equal to 0,6 · z · E where z is the Leonhardt factor which accounts for the influence of the in situ
Bh 2
(native) soil (zone E ) and trench width (see Figure 1) and E corresponds to Spangler’s E'.
3 2
Figure 2 — Soil distribution according to Spangler and ATV-A 127
6 Soil load
6.1 General
The calculation of soil loads needs to consider both initial and long-term loadings. Short-term loading can be related
to the initial pipe deflection which is a property that is often used as a measure of installation quality. Long-term
loading defines the expected long-term deflection of the pipe and is therefore related to service life.
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© ISO
ISO/TR 10465-2:1999(E)
6.2 Initial loadings
6.2.1 AWWA procedure
In the AWWA procedure, the soil loading is assumed to be a soil prism in all cases. The prism has a height equal to
the depth of cover and its width is equal to the outside diameter of the pipe. The prismatic equation is always used,
and arching or silo theory is not considered.
The vertical soil load W is calculated using equation (1):
c
W = g · h (1)
c
where
2
W is the vertical soil load, in N/m ;
c
3
gis the bulk density of the soil (i.e. its weight per unit volume), in N/m ;
h is the depth of cover, in m.
6.2.2 ATV procedure
The ATV procedure for calculating soil loads is more detailed than that used by AWWA. The procedure is based on
silo theory which assumes that frictional forces against the trench walls will lead to a reduction in the pressure
acting on the pipe due to the soil. It is assumed that these friction conditions are maintained for the whole life of the
pipe.
Trench and embankment conditions are considered, as well as the angle of the trench walls and the relationship
between the horizontal and vertical soil pressures.
When the trench width is four times the pipe diameter or greater, then ATV assumes that embankment conditions
exist and consequently the soil load is a prismatic load.
The remainder of this subclause is an outline of the ATV procedure for calculating the soil load. Because of the
detailed nature of this approach, the reader is strongly recommended to read ATV-A 127 in detail very carefully.
The vertical pressure p due to the prismatic soil load is modified by a factor c in equation (2) to take into account
Eb
the friction effects mentioned above:
p = c · g · h (2)
Eb
Similarly, friction effects change the soil pressure p applied by a uniformly distributed load acting over a limited
o
area, and this is expressed using the factor c :
ob
p' = c · p (3)
o obo
NOTE Subscripts have been used above to indicate that c is the reduction factor for soil load, c is the reduction factor for
o
a uniformly distributed load (UDL), c is the reduction factor for soil loads which take into account the trench angle b or w (see
b
Figure 3) and c is the reduction factor for a UDL which takes into account the trench angle.
ob
To use these reduction factors, the procedures require that:
a) <   (for c)
E E
1 3
b) E , E  (for c)
1 3 o
If either of these conditions is not met or if the installation is considered to be of the embankment type, then the
factors c and c are taken to be equal to 1.
o
The reduction factors are derived using equations (4) and (5):
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© ISO
ISO/TR 10465-2:1999(E)
h
 
-·2··K tand 
1
Łłb
1-e
c= (4)
h
2···K tand
1
b
 h 
-·2··K tand 
1
Łłb
c= e (5)
o
where
e is the base of natural logarithms (2,718 281 8);
2
p is the vertical soil pressure due to the soil load, in N/m ;
E
cis the reduction factor for silo theory;
b
3
gis the bulk density of the soil (i.e. its weight per unit volume), in N/m ;
h is the depth of cover, in m;
cis the silo theory reduction factor for UDL (uniformly distributed load);
ob
2
p is the soil pressure due to the UDL, in N/m ;
o
b is the trench width, in m;
dis the trench wall friction angle, in degrees;
K is the ratio of the horizontal to the vertical soil pressure.
1
To help in other parts of the procedures, there are four classes of installation for the zone of material above the pipe
zone (see Table 1)
Table 1 — Installation conditions
Class Description
Compacted fill against undisturbed native soil without assessing degree of compaction.
A1
These conditions also apply to sheet piles left in after installation.
A2 Vertical timber sheeting or lightweight sheet piles or shields which are gradually removed
in stages during installation or
uncompacted fill or
soaking of the fill (valid for soil group G1).
A3 Vertical sheeting or shields withdrawn in one operation after all the fill material has been
put in place.
A4 Same as A1 but degree of compaction is assessed. These conditions shall not be used
with soil group G4.
For all the installation conditions detailed in Table 1, the lateral soil pressure acting on the trench walls, expressed
in terms of the vertical to horizontal soil pressure ratio K , is assumed to be 0,5. Under these conditions, equations
1
(4) and (5) reduce to equations (4a) and (5a):
h
 
-· tand 
Łłb
-1e
c= (4a)
h
·tand
b
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© ISO
ISO/TR 10465-2:1999(E)
 h 
-· tand 
Łłb
c= e (5a)
o
The wall friction angle is derived from one of the equations given in Table 2, depending on the fill conditions.
Table 2 — Wall friction angle dd
Class Equation
A1d = 0,66 · j* (6a)
A2d = 0,33 · j* (6b)
A3d = 0 (6c)
A4d = j* (6d)
NOTE j* is the internal friction angle, in degrees, of the soil.
In the case where d = 0, the reduction factors c and c are taken to be equal to 1.
o
The other reduction factor
...