ISO/TR 18228-4:2022
(Main)Design using geosynthetics — Part 4: Drainage
Design using geosynthetics — Part 4: Drainage
This document outlines the criteria for evaluating the available and the required flow rate of geosynthetics in various situations, provides a summary of the available laboratory testing, and lists the safety factors and reduction factors that can be applied to the parameters when designing using geosynthetics for drainage systems.
Conception utilisant des géosynthétiques — Partie 4: Drainage
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 18228-4
First edition
2022-03
Design using geosynthetics —
Part 4:
Drainage
Design pour géosynthétiques —
Partie 4: Drainage
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Symbols and abbreviations . 1
4 Concepts . 6
5 Applications .8
6 Materials . 9
6.1 Components of draining geocomposites . 9
6.2 Filter Component of draining geocomposites . 9
6.3 Drainage cores . 10
6.4 Definitions and acronyms for the various products . 10
7 Properties relevant to design .10
8 Darcy’s law.10
9 Subsurface drainage structures .11
10 Geosynthetic properties .11
11 Geotextile filter performance and filter criteria .12
12 Geocomposite drainage systems design.12
12.1 General .12
12.2 Calculation of input flow rate .13
12.2.1 General .13
12.2.2 Rainfall on sloping surface . 13
12.2.3 Filtration from soil or rock . 16
12.3 Calculation of available flow rate. 17
12.3.1 Hydraulic gradient . 17
12.3.2 Discharge capacity . 19
12.3.3 Pressure applied to the geocomposite . 19
12.3.4 Materials in contact with the faces of the drainage geocomposite . 21
12.3.5 Compressive behaviour of geocomposites .22
12.3.6 Factors influencing the available flow rate . 24
12.3.7 Laboratory tests for water flow capacity of geocomposites .25
12.3.8 Specific situations . 27
12.3.9 Flow rate versus hydraulic gradient .29
12.3.10 Flow rate versus viscosity . 31
12.3.11 General procedure for evaluating the available flow rate of the
geocomposites . 33
12.4 Selection of the geocomposite .34
12.5 Equivalence with a granular drainage layer .34
12.5.1 General .34
12.5.2 Equivalence for water flow on slopes .34
12.5.3 Equivalence for vertical water flow .39
Annex A (informative) The movement of water in the ground .41
Annex B (informative) Reduction factors .53
Bibliography .60
iii
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
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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 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
Introduction
The ISO 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 drainage function. Details of design methodology
adopted in a number of regions are provided.
[10]
Parts of this document have been adapted from Comité français des géosynthétiques, 2014 .
v
TECHNICAL REPORT ISO/TR 18228-4:2022(E)
Design using geosynthetics —
Part 4:
Drainage
1 Scope
This document outlines the criteria for evaluating the available and the required flow rate of
geosynthetics in various situations, provides a summary of the available laboratory testing, and lists
the safety factors and reduction factors that can be applied to the parameters when designing using
geosynthetics for drainage systems.
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 and the following
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/
3.1 Symbols and abbreviations
O characteristic opening size of a geosynthetic (µm)
k coefficient of permeability normal to the plane(m/s)
n
q flux(l/m ⋅s)
n
v-index velocity index(mm/s)
-1
ψ permittivity(s )
ϑ transmissivity (m /s/m or l/s/m)
GCD acronym used for draining geocomposites
dQ/dt volumetric flow rate of water through the soil (m /s or l/s)
A bulk cross-sectional area through which the flow occurs (m )
h hydraulic head (m)
l distance travelled by the bulk water flow (m)
dh/dl hydraulic gradient (dimensionless)
K hydraulic conductivity or permeability of the soil (m/s)
q equal to (dQ/dt), volumetric flow rate (m /s or l/s)
i equal to (dh/dl), hydraulic gradient (dimensionless)
q in-plane flow capacity, equal to the volumetric flow rate of water and/or other liquids
p
per unit width of specimen, at defined gradients in the plane of a product (l/s⋅m).
k coefficient of permeability in the plane, equal to the ratio be
...
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