ISO/TR 18228-2:2021
(Main)Design using geosynthetics — Part 2: Separation
Design using geosynthetics — Part 2: Separation
This document provides general considerations to support the design guidance to geotechnical and civil engineers involved in the design of structures in which a geotextile is used to fulfil the function of separation of soils and below ground structures in contact with natural soils and fills. These considerations are always based on installed soils, the installation process and on the strength and/or deformation behaviour of geosynthetics.
Conception utilisant des géosynthétiques — Partie 2: Séparation
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 18228-2
First edition
2021-10
Design using geosynthetics —
Part 2:
Separation
Conception utilisant des géosynthétiques —
Partie 2: Séparation
Reference number
ISO/TR 18228-2:2021(E)
© ISO 2021
---------------------- Page: 1 ----------------------
ISO/TR 18228-2:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 18228-2:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Different concepts . 1
4.1 General . 1
4.2 GRK classification . 1
4.2.1 General . 1
4.2.2 Stresses resulting from fill material . 2
4.2.3 Stresses resulting from installation and construction operation . 2
4.2.4 Determination of required geotextile robustness class “GRK” . 3
4.3 American Association of State Highway and Transportation Officials (AASHTO)
M288 . 4
4.3.1 General . 4
4.3.2 General properties . 4
4.4 Other concepts . 6
5 Installation .7
Bibliography . 8
iii
© ISO 2021 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/TR 18228-2:2021(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 procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 221, Geosynthetics.
A list of all parts in the ISO/TR 18228 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
© ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 18228-2:2021(E)
Introduction
The ISO/TR 18228 series provides guidance for designs using geosynthetics for soils and below ground
structures in contact with natural soils, fills and asphalt. The series contains 10 parts which cover
designs using geosynthetics, including guidance for characterization of the materials to be used and
other factors affecting the design and performance of the systems which are particular to each part,
with ISO/TR 18228-1 providing general guidance relevant to the subsequent parts of the series.
The series is generally written in a limit state format and guidelines are provided in terms of partial
material factors and load factors for various applications and design lives, where appropriate.
This document includes information relating to the separation function. Details of design methodology
adopted in a number of regions are provided.
v
© ISO 2021 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL REPORT ISO/TR 18228-2:2021(E)
Design using geosynthetics —
Part 2:
Separation
1 Scope
This document provides general considerations to support the design guidance to geotechnical and
civil engineers involved in the design of structures in which a geotextile is used to fulfil the function of
separation of soils and below ground structures in contact with natural soils and fills.
These considerations are always based on installed soils, the installation process and on the strength
and/or deformation behaviour of geosynthetics.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 10318-1, Geosynthetics — Part 1: Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10318-1 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Different concepts
4.1 General
There are several different concepts available worldwide for the design and application of geosynthetics
for separation; several are presented in this document. The contents of the original documents are
reproduced. However other concepts and approaches might also be available or applicable. The user of
this document is intended to always refer to the most up to date version of the documents quoted.
4.2 GRK classification
4.2.1 General
[22]
This subclause presents a summary of the German GRK (Geotextilrobustheitsklasse) guidance for
the use of geosynthetics and geosynthetic-related products mainly in separation.
The GRK is based on two characteristics, mass per unit area and strength. The development of this
system is based on on-site testing and evaluation of robustness.
The mass per unit area is usually determined in accordance with ISO 9864.
1
© ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/TR 18228-2:2021(E)
In the case of non-woven geotextiles, the puncture force is usually measured in accordance with
ISO 12236. In the case of woven geotextiles, the strength is usually measured in accordance with
ISO 10319 in the weakest direction.
4.2.2 Stresses resulting from fill material
The GRK evaluation of which product to use is undertaken on the basis of several site-specific factors.
This considers the type of soil that is used as fill material, the bearing capacity of the subgrade soil, as
well as effects resulting from construction/installation operations.
The rut depth is not reduced substantially by the choice of a higher geotextile robustness class or a
layer of fill material with increased thickness or shear parameters. Extreme stresses, resulting for
example, from angular fill material and site traffic, which exceed the specifications of Table 1, can lead
to more stringent requirements and would normally be considered on the basis of local experience or
by preliminary tests.
Table 1 is applicable to fine grained, sandy subgrade soils (SW, SE, SI, SU*, SU).
a
Table 1 — Stress to geotextiles resulting from fill material
Appreciation
Rounded fill material Angular fill material
level
Applications where mechanical stresses resulting from the fill material have no influence
AS 1
on the selection
Coarse or mixed granular soils according to
AS 2 DIN 18196 (SW, SE, SI, GW, GE, GI, SU, SU*, GU,
GU*)
Coarse or mixed granular soils ≤ 40 % stones Coarse or mixed granular soils according
AS 3 and cobbles DIN 18196 (SW, SE, SI, GW, GE, GI, SU, SU*,
GU, GU*)
Coarse or mixed granular soils > 40 % stones Coarse or mixed granular soils ≤ 40 %
AS 4
and cobbles stones and cobbles
Coarse or mixed granular soils > 40 %
AS 5
stones and cobbles
a
Processed fill material (e.g. crushed stone, recycled material) is classified according to particle size and shape.
* Indicates “very” silty.
[22]
NOTE For definitions of soil types, please refer to the original GRK document .
When the geotextile is placed on top of coarse or mixed granular subgrade soils (GW, GE, GI, GU, GU*,
GT, GT*) the application level AS 2 to AS 4 would normally be increased by one level.
4.2.3 Stresses resulting from installation and construction operation
Rutting on the surface of a trafficked fill layer is caused by site traffic loading, which is counteracted by
the resistance of the “fill material and subgrade soil” system. The resistance arises from the interaction
of stiffness and deformability of the subgrade soil, as well as from the thickness and shear strength of
the fill material. The rut depth cannot be influenced by the separation layer. The rut depth is a measure
of the stress level applied to separation layers.
The geotextile robustness classes resulting from fill material and construction operation stresses
given in Table 2 describe the stress level applied to the separation layer. If a separation product with
corresponding geotextile robustness class is applied, it can be assumed that it will withstand these
stresses and thereby maintains its separation function.
2
© ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TR 18228-2:2021(E)
Table 2 — Stress level resulting from installation and construction operation to the geotextile
Stress level Installation of fill Compaction Stress resulting from site traffic
material (fill above geotextile separation layer)
AB 1 Manual No influence No site traffic
AB 2 Equipment Equipment Estimated rut depth < 5 cm
AB 3 Equipment Equipment Estimated rut depth 5 cm ≤ 15 cm
AB 4 Equipment Equipment Estimated rut depth 15 cm ≤ 30 cm
AB 5 Equipment Equipment Estimated rut depth > 30 cm
4.2.4 Determination of required geotextile robustness class “GRK”
The robustness classes GRK 1 and GRK 2 will never result from the evaluation in Table 3. Therefore,
these two classes have been deleted in the latest revision of the GRK system. The required geosynthetic
characteristics are provided for each class in Tables 4, 5 and 6.
Table 3 — Determination of required geotextile robustness class resulting
...
TECHNICAL ISO/TR
REPORT 18228-2
First edition
Design using geosynthetics —
Part 2:
Separation
Conception utilisant des géosynthétiques —
Partie 2: Séparation
PROOF/ÉPREUVE
Reference number
ISO/TR 18228-2:2021(E)
©
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TR 18228-2:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 18228-2:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Different concepts . 1
4.1 General . 1
4.2 GRK classification . 1
4.2.1 General. 1
4.2.2 Stresses resulting from fill material . 2
4.2.3 Stresses resulting from installation and construction operation . 2
4.2.4 Determination of required geotextile robustness class “GRK” . 3
4.3 American Association of State Highway and Transportation Officials (AASHTO) M288 . 4
4.3.1 General. 4
4.3.2 General properties. 4
4.4 Other concepts . 6
5 Installation . 7
Bibliography . 8
© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TR 18228-2:2021(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 procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 221, Geosynthetics.
A list of all parts in the ISO/TR 18228 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 18228-2:2021(E)
Introduction
The ISO/TR 18228 series provides guidance for designs using geosynthetics for soils and below ground
structures in contact with natural soils, fills and asphalt. The series contains 10 parts which cover
designs using geosynthetics, including guidance for characterization of the materials to be used and
other factors affecting the design and performance of the systems which are particular to each part,
with ISO/TR 18228-1 providing general guidance relevant to the subsequent parts of the series.
The series is generally written in a limit state format and guidelines are provided in terms of partial
material factors and load factors for various applications and design lives, where appropriate.
This document includes information relating to the separation function. Details of design methodology
adopted in a number of regions are provided.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v
---------------------- Page: 5 ----------------------
TECHNICAL REPORT ISO/TR 18228-2:2021(E)
Design using geosynthetics —
Part 2:
Separation
1 Scope
This document provides general considerations to support the design guidance to geotechnical and
civil engineers involved in the design of structures in which a geotextile is used to fulfil the function of
separation of soils and below ground structures in contact with natural soils and fills.
These considerations are always based on installed soils, the installation process and on the strength
and/or deformation behaviour of geosynthetics.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 10318-1, Geosynthetics — Part 1: Terms and definitions
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in ISO 10318-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Different concepts
4.1 General
There are several different concepts available worldwide for the design and application of geosynthetics
for separation; several are presented in this document. The contents of the original documents are
reproduced. However other concepts and approaches might also be available or applicable. The user of
this document is intended to always refer to the most up to date version of the documents quoted.
4.2 GRK classification
4.2.1 General
[22]
This subclause presents a summary of the German GRK (Geotextilrobustheitsklasse) guidance for
the use of geosynthetics and geosynthetic-related products mainly in separation.
The GRK is based on two characteristics, mass per unit area and strength. The development of this
system is based on on-site testing and evaluation of robustness.
The mass per unit area is usually determined in accordance with ISO 9864.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 1
---------------------- Page: 6 ----------------------
ISO/TR 18228-2:2021(E)
In the case of non-woven geotextiles, the puncture force is usually measured in accordance with
ISO 12236. In the case of woven geotextiles, the strength is usually measured in accordance with
ISO 10319 in the weakest direction.
4.2.2 Stresses resulting from fill material
The GRK evaluation of which product to use is undertaken on the basis of several site-specific factors.
This considers the type of soil that is used as fill material, the bearing capacity of the subgrade soil, as
well as effects resulting from construction/installation operations.
The rut depth is not reduced substantially by the choice of a higher geotextile robustness class or a
layer of fill material with increased thickness or shear parameters. Extreme stresses, resulting for
example, from angular fill material and site traffic, which exceed the specifications of Table 1, can lead
to more stringent requirements and would normally be considered on the basis of local experience or
by preliminary tests.
Table 1 is applicable to fine grained, sandy subgrade soils (SW, SE, SI, SU*, SU).
a
Table 1 — Stress to geotextiles resulting from fill material
Appreciation
Rounded fill material Angular fill material
level
Applications where mechanical stresses resulting from the fill material have no influence
AS 1
on the selection
Coarse or mixed granular soils according
AS 2 DIN 18196 (SW, SE, SI, GW, GE, GI, SU, SU*, GU,
GU*)
Coarse or mixed granular soils ≤ 40 % stones Coarse or mixed granular soils according
AS 3 and cobbles DIN 18196 (SW, SE, SI, GW, GE, GI, SU, SU*,
GU, GU*)
Coarse or mixed granular soils > 40 % stones Coarse or mixed granular soils ≤ 40 %
AS 4
and cobbles stones and cobbles
Coarse or mixed granular soils > 40 %
AS 5
stones and cobbles
a
Processed fill material (e.g. crushed stone, recycled material) is classified according to particle size and shape.
* Indicates “very” silty.
[22]
NOTE For definitions of soil types, please refer to the original GRK document .
When the geotextile is placed on top of coarse or mixed granular subgrade soils (GW, GE, GI, GU, GU*,
GT, GT*) the application level AS 2 to AS 4 would normally be increased by one level.
4.2.3 Stresses resulting from installation and construction operation
Rutting on the surface of a trafficked fill layer is caused by site traffic loading, which is counteracted by
the resistance of the “fill material and subgrade soil” system. The resistance arises from the interaction
of stiffness and deformability of the subgrade soil, as well as from the thickness and shear strength of
the fill material. The rut depth cannot be influenced by the separation layer. The rut depth is a measure
of the stress level applied to separation layers.
The geotextile robustness classes resulting from fill material and construction operation stresses
given in Table 2 describe the stress level applied to the separation layer. If a separation product with
corresponding geotextile robustness class is applied, it can be assumed that it will withstand these
stresses and thereby maintains its separation function.
2 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TR 18228-2:2021(E)
Table 2 — Stress level resulting from installation and construction operation to the geotextile
Stress level Installation of fill Compaction Stress resulting from site traffic
material (fill above geotextile separation layer)
AB 1 Manual No influence No site traffic
AB 2 Equipment Equipment Estimated rut depth < 5 cm
AB 3 Equipment Equipment Estimated rut depth 5 cm ≤ 15 cm
AB 4 Equipment Equipment Estimated rut depth 15 cm ≤ 30 cm
AB 5 Equipment Equipment Estimated rut depth > 30 cm
4.2.4 Determination of required geotextile robustness class “GRK”
The robustness classes GRK 1 and GRK 2 will never result from the evaluation in Table 3. Therefore,
these two classes have been deleted in the latest revision of the GRK system. The required geosynthetic
characteristics are provided for each class in Tables 4, 5 and 6.
Table 3 — Determination of required geotextile robustness class resulting from fill material
and construction operation stresses
Application Stress condition construction operati
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.