EN ISO 19901-4:2016

SLOVENSKI STANDARD
01-oktober-2016
1DGRPHãþD
SIST EN ISO 19901-4:2004
,QGXVWULMD]DSUHGHODYRQDIWHLQ]HPHOMVNHJDSOLQD3RVHEQH]DKWHYH]DQDIWQH
SORãþDGLGHO2EUDYQDYDJHRWHKQLþQLKLQWHPHOMQLK]QDþLOQRVWLSURMHNWLUDQMD
,62
Petroleum and natural gas industries - Specific requirements for offshore structures -
Part 4: Geotechnical and foundation design considerations (ISO 19901-4:2016)
Erdöl- und Erdgasindustrie - Besondere Anforderungen an Offshore-Bauwerke - Teil 4:
Geotechnische und Fundament-Auslegungsmerkmale (ISO 19901-4:2016)
Industries du pétrole et du gaz naturel - Exigences spécifiques relatives aux structures
en mer - Partie 4: Bases conceptuelles des fondations (ISO 19901-4:2016)
Ta slovenski standard je istoveten z: EN ISO 19901-4:2016
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 19901-4
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2016
EUROPÄISCHE NORM
ICS 75.180.10 Supersedes EN ISO 19901-4:2003
English Version
Petroleum and natural gas industries - Specific
requirements for offshore structures - Part 4: Geotechnical
and foundation design considerations (ISO 19901-4:2016)
Industries du pétrole et du gaz naturel - Exigences Erdöl- und Erdgasindustrie - Besondere
spécifiques relatives aux structures en mer - Partie 4: Anforderungen an Offshore-Bauwerke - Teil 4:
Bases conceptuelles des fondations (ISO 19901- Geotechnische und Fundament-Auslegungsmerkmale
4:2016) (ISO 19901-4:2016)
This European Standard was approved by CEN on 2 July 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19901-4:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 19901-4:2016) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries"
in collaboration with Technical Committee CEN/TC 12 “Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries” the secretariat of which is held by NEN
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2017, and conflicting national standards
shall be withdrawn at the latest by February 2017.
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 document supersedes EN ISO 19901-4:2003.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 19901-4:2016 has been approved by CEN as EN ISO 19901-4:2016 without any
modification.
INTERNATIONAL ISO
STANDARD 19901-4
Second edition
2016-07-15
Petroleum and natural gas
industries — Specific requirements
for offshore structures —
Part 4:
Geotechnical and foundation design
considerations
Industries du pétrole et du gaz naturel — Exigences spécifiques
relatives aux structures en mer —
Partie 4: Bases conceptuelles des fondations
Reference number
ISO 19901-4:2016(E)
©
ISO 2016
ISO 19901-4:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

ISO 19901-4:2016(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 2
4 Symbols and abbreviated terms . 4
4.1 General . 4
4.2 Symbols for shallow foundations design . 4
4.3 Symbols for pile foundations design . 7
4.4 Symbols for soil-structure interaction for auxiliary subsea structures, risers
and flowlines .10
4.5 Symbols for design of anchors for stationkeeping systems .11
4.6 Abbreviated terms .12
5  General requirements .13
5.1 General .13
5.2 Design cases and safety factors .14
5.3 Characteristic values of soil properties .14
5.4 Testing and instrumentation .15
6  Geotechnical data acquisition and identification of hazards .16
6.1 General .16
6.2 Shallow geophysical investigation .16
6.3 Geological modelling and identification of hazards .17
6.3.1 General.17
6.3.2 Earthquakes .17
6.3.3 Fault planes .17
6.3.4 Seafloor instability .17
6.3.5 Scour and sediment mobility .18
6.3.6 Shallow gas .18
6.3.7 Seabed subsidence .18
6.4 Carbonate soils .19
7 Design of shallow foundations .19
7.1 General .19
7.2 Principles .20
7.2.1 General principles .20
7.2.2 Sign conventions, nomenclature and action reference point .21
7.2.3 Action transfer .21
7.2.4 Idealization of foundation area and the effective area concept .21
7.3 Acceptance criteria and design considerations .22
7.3.1 Action and material factors .22
7.3.2 Use in design . . .22
7.3.3 Special cases .23
7.3.4 Additional design considerations .24
7.3.5 Alternative method of design based on yield surfaces .26
7.3.6 Selection of soil parameter values for design .27
7.4 Stability of shallow foundations .27
7.4.1 Assessment of bearing capacity .27
7.4.2 Assessment of sliding capacity .29
7.4.3 Assessment of torsional capacity .31
7.5 Serviceability (displacements and rotations) .31
7.5.1 General.31
7.5.2 Displacement under static loading.31
7.5.3 Displacement under dynamic and cyclic actions .34
ISO 19901-4:2016(E)
7.5.4 Other contributors to foundation settlement .34
7.6 Other design considerations .34
7.6.1 Hydraulic stability .34
7.6.2 Installation, retrieval and removal .34
8 Pile foundation design .35
8.1 Pile capacity for axial compression .35
8.1.1 General.35
8.1.2 Axial pile capacity .36
8.1.3 Skin friction and end bearing in cohesive soils .37
8.1.4 Skin friction and end bearing in cohesionless soils .38
8.1.5 Skin friction and end bearing of grouted piles in rock .40
8.2 Pile capacity for axial tension .41
8.3 Axial pile performance .41
8.3.1 Static axial behaviour of piles .41
8.3.2 Cyclic axial behaviour of piles .41
8.4 Soil reaction for piles under axial compression .41
8.4.1 Axial shear transfer t–z curves .41
8.4.2 End bearing resistance–displacement, Q–z, curve .42
8.5 Soil reaction for piles under lateral actions .44
8.5.1 General.44
8.5.2 Lateral capacity for soft clay .45
8.5.3 Lateral soil resistance–displacement p−y curves for soft clay .45
8.5.4 Lateral capacity for stiff clay .45
8.5.5 Lateral soil resistance–displacement p–y curves for stiff clay .46
8.5.6 Lateral capacity for sand .47
8.5.7 Lateral soil resistance – displacement p–y curves for sand .48
8.6 Pile group behaviour .49
8.6.1 General.49
8.6.2 Axial behaviour .49
8.6.3 Lateral behaviour .50
9 Pile installation assessment .50
9.1 General .50
9.2 Drivability studies .51
9.3 Obtaining required pile penetration .51
9.4 Driven pile refusal .52
9.5 Pile refusal remedial measures .52
9.5.1 Review of hammer performance .52
9.5.2 Re-evaluation of design penetration .52
9.5.3 Modifications to piling procedures .52
9.6 Selection of pile hammer and stresses during driving .53
9.7 Use of hydraulic hammers .53
9.8 Drilled and grouted piles .54
9.9 Belled piles .55
9.10 Grouting pile-to-sleeve connections .55
9.11 Pile installation data .55
9.12 Installation of conductors and shallow well drilling .55
10  Soil-structure interaction for auxiliary subsea structures, risers and flowlines .56
11  Design of anchors for floating structures .56
Annex A (informative) Additional information and guidance .57
Bibliography .175
iv © ISO 2016 – All rights reserved

ISO 19901-4:2016(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 on 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 the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures
for the petroleum, petrochemical and natural gas industries, Subcommittee SC 7, Offshore structures.
This second edition cancels and replaces the first edition (ISO 19901-4:2003), which has been
technically revised.
ISO 19901 consists of the following parts, under the general title Petroleum and natural gas industries —
Specific requirements for offshore structures:
— Part 1: Metocean design and operating considerations
— Part 2: Seismic design procedures and criteria
— Part 3: Topsides structure
— Part 4: Geotechnical and foundation design considerations
— Part 5: Weight control during engineering and construction
— Part 6: Marine operations
— Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
— Part 8: Marine soil investigations
The following part is under preparation:
— Part 9: Structural integrity management
ISO 19901 is one of a series of standards for offshore structures. The full series consists of the following
International Standards which are relevant to offshore structures for the petroleum and natural gas
industries:
— ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
ISO 19901-4:2016(E)
— ISO 19901 (all parts), Petroleum and natural gas industries — Specific requirements for offshore
structures
— ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
— ISO 19903, Petroleum and natural gas industries — Fixed concrete offshore structures
— ISO 19904, Petroleum and natural gas industries — Floating offshore structures
— ISO 19905-1, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
units — Part 1: Jack-ups
— ISO/TR 19905-2, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
units — Part 2: Jack-ups commentary and detailed sample calculation
— ISO 19905-3, Petroleum and natural gas industries — Site specific assessment of mobile offshore
units — Part 3: Floating units (under preparation)
— ISO 19906, Petroleum and natural gas industries — Arctic offshore structures
Other ISO standards can have implications for the geotechnical design of foundations for offshore
structures, in particular:
— ISO 13623 (all parts), Petroleum and natural gas industries — Pipeline transportation systems
— ISO 13628 (all parts), Petroleum and natural gas industries — Design and operation of subsea
production systems
vi © ISO 2016 – All rights reserved

ISO 19901-4:2016(E)
Introduction
The International Standards for offshore structures, ISO 19900 to ISO 19906, constitute a common basis
covering those aspects that address design requirements and assessments of all offshore structures
used by the petroleum and natural gas industries worldwide. Through their application, the intention
is to achieve reliability levels appropriate for manned and unmanned offshore structures, whatever the
type of structure and the nature of the materials used.
It is important to recognize that structural integrity is an overall concept comprising models for
describing actions, structural analyses, design rules, safety elements, workmanship, quality control
procedures and national requirements, all of which are mutually dependent. The modification of one
aspect of design in isolation can disturb the balance of reliability inherent in the overall concept or
structural system. The implications involved in modifications, therefore, need to be considered in
relation to the overall reliability of all offshore structural systems.
For foundations, some additional considerations apply. These include the time, frequency and rate at
which actions are applied, the method of foundation installation, the properties of the surrounding soil,
the overall behaviour of the seabed, effects from adjacent structures and the results of drilling into the
seabed. All of these, and any other relevant information, need to be considered in relation to the overall
reliability of the foundation.
These International Standards are intended to provide wide latitude in the choice of structural
configurations, materials and techniques without hindering innovation. The design practice for the
foundations of offshore structures has proved to be an innovative and evolving process over the years.
This evolution is expected to continue and is encouraged. Therefore, circumstances can arise when the
procedures described herein or in ISO 19900 to ISO 19906 (or elsewhere) are insufficient on their own
to ensure that a safe and economical foundation design is achieved.
Seabed soils vary. Experience gained at one location is not necessarily applicable at another, and extra
caution is necessary when dealing with unconventional soils or unfamiliar foundation concepts. Sound
engineering judgment is therefore necessary in the use of this part of ISO 19901.
For an offshore structure, the action effects at the interface between the structure’s subsystem and
the foundation’s subsystem(s) are internal forces, moments and deformations. When addressing
the foundation’s subsystem(s) in isolation, these internal forces, moments and deformations can be
considered as actions on the foundation’s subsystem(s) and this approach is followed in this part of
ISO 19901.
Some background to and guidance on the use of this part of ISO 19901 is provided for information in
Annex A. Guidance on foundations in carbonate soils is provided for information in A.6.4, but there is, as
yet, insufficient knowledge and understanding of such soils to produce normative requirements.
In this part of ISO 19901, in accordance with the latest edition of the ISO/IEC Directives, Part 2, the
following verbal forms are used:
— ‘shall’ and ‘shall not’ are used to indicate requirements strictly to be followed in order to comply
with the document and from which no deviation is permitted;
— ‘should’ and ‘should not’ are used to indicate that among several possibilities one is recommended
as particularly suitable, without mentioning or excluding others, or that a certain course of action is
preferred but not necessarily required, or that (in the negative form) a certain possibility or course
of action is deprecated but not prohibited;
— ‘may’ and ‘need not’ are used to indicate a course of action permissible within the limits of the
document;
— ‘can’ and ‘cannot’ are used for statements of possibility and capability, whether material, physical
or causal.
INTERNATIONAL STANDARD ISO 19901-4:2016(E)
Petroleum and natural gas industries — Specific
requirements for offshore structures —
Part 4:
Geotechnical and foundation design considerations
1 Scope
This part of ISO 19901 contains provisions for those aspects of geoscience and foundation engineering
that are applicable to a broad range of offshore structures, rather than to a particular structure type.
Such aspects are:
— site and soil characterization;
— identification of hazards;
— design and installation of shallow foundations supported by the seabed;
— design and installation of pile foundations;
— soil-structure interaction for auxiliary structures, e.g. subsea production systems, risers and
flowlines (guidance given in A.10);
— design of anchors for the stationkeeping systems of floating structures (guidance given in A.11).
Particular requirements for marine soil investigations are detailed in ISO 19901-8.
Aspects of soil mechanics and foundation engineering that apply equally to offshore and onshore
structures are not addressed. The user of this part of ISO 19901 is expected to be familiar with such
aspects.
ISO 19901-4 outlines methods developed primarily for the design of shallow foundations with an
embedded length (L) to diameter (D) ratio L/D < 1 (Clause 7) and relatively long and flexible pile
foundations with L/D > 10 (Clause 8). This part of ISO 19901 does not apply to intermediate foundations
with 1 < L/D < 10. Such intermediate foundations, often known as ‘caisson foundations’, comprise either
shallow foundations with skirts penetrating deeper into the seabed than the width of the foundation,
or shorter, more rigid and larger diameter piles than those traditionally used for founding offshore
structures. The design of such foundations can require specific analysis methods; it is important
that any extrapolation from the design methods described in this part of ISO 19901 to intermediate
foundations be treated with care and assessed by a geotechnical specialist.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
ISO 19901-1, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 1: Metocean design and operating considerations
ISO 19901-2, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 2: Seismic design procedures and criteria
ISO 19901-4:2016(E)
ISO 19901-3, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 3: Topsides structure
ISO 19901-5, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 5: Weight control during engineering and construction
ISO 19901-6, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 6: Marine operations
ISO 19901-7:2013, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
ISO 19901-8, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 8: Marine soil investigations
ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
ISO 19903, Petroleum and natural gas industries — Fixed concrete offshore structures
ISO 19905-1, Petroleum and natural gas industries — Site-specific assessment of mobile offshore units —
Part 1: Jack-ups
ISO 19906, Petroleum and natural gas industries — Arctic offshore structures
ISO/TR 19905-2, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
units — Part 2: Jack-ups commentary and detailed sample calculation
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 19900, ISO 19901 (all parts)
and the following apply.
3.1
action
external load applied to the structure (direct action) or an imposed deformation or acceleration
(indirect action)
Note 1 to entry: An imposed deformation can be caused by fabrication tolerances, differential settlement,
temperature change or moisture variation. An earthquake typically generates imposed accelerations.
[SOURCE: ISO 19900:2013, 3.1]
3.2
action factor
partial safety factor applied to a design action
3.3
basic variable
one of a specified set of variables representing physical quantities which characterize actions,
environmental influences, geometric quantities, or material properties including soil properties
[SOURCE: ISO 19900:2013, 3.7]
3.4
characteristic value
value assigned to a basic variable associated with a prescribed probability of not being violated by
unfavourable values during some reference period
Note 1 to entry: The characteristic value is the main representative value. In some design situations a variable
can have two characteristic values, an upper and a lower value.
2 © ISO 2016 – All rights reserved

ISO 19901-4:2016(E)
Note 2 to entry: For variable actions, the characteristic value corresponds to either of the following (see
ISO 2394:2015, 2.2.30):
— an upper value with an intended probability of not being exceeded or a lower value with an intended
probability of being achieved, during some specific reference period;
— a nominal value, which may be specified in cases where a statistical distribution is not known.
[SOURCE: ISO 19900:2013, 3.10]
3.5
design actions
combination of representative actions and partial safety factors representing a design situation for use
in checking the acceptability of a design
3.6
design value
value derived from the representative value for use in the design verification procedure
[SOURCE: ISO 19900:2013, 3.18]
3.7
drained condition
condition whereby the applied stresses and stress changes are supported by the soil skeleton and do
not cause a change in pore pressure
[SOURCE: ISO 19901-8:2014, 3.11]
3.8
effective foundation area
reduced foundation area having its geometric centre at the point where the resultant action vector
intersects the foundation base level
3.9
limit state
state beyond which the structure no longer satisfies the relevant design criteria
[SOURCE: ISO 19900:2013, 3.2]
3.10
material factor
partial safety factor applied to the characteristic strength of the soil, the value of which reflects the
uncertainty or variability of the material property
Note 1 to entry: See ISO 19900.
3.11
representative value
value assigned to a basic variable for verification of a limit state
[SOURCE: ISO 19900:2013, 3.38]
3.12
resistance
capacity of a component, or a cross-section of a component, to withstand action effects without failure
[SOURCE: ISO 19900:2013, 3.39]
3.13
resistance factor
partial safety factor applied to the characteristic capacity of a foundation, the value of which reflects
the uncertainty or variability of the component resistance including those of material property
ISO 19901-4:2016(E)
3.14
scour
removal of seabed soils caused by currents, waves and ice
[SOURCE: ISO 19900:2013, 3.43]
3.15
seabed
materials below the seafloor, whether of soils such as sand, silt or clay, cemented materials or of rock
Note 1 to entry: Offshore foundations are most commonly installed in soils, and the terminology in this part of
ISO 19901 reflects this. However, the requirements equally apply to cemented seabed materials and rock. Thus,
the term ‘soil’ does not exclude any other material at or below the seafloor.
3.16
seafloor
interface between the sea and the seabed
3.17
serviceability
ability of a structure or structural member to perform adequately for a normal use under all
expected actions
[SOURCE: ISO 2394:2015, 2.1.32]
3.18
settlement
permanent downward movement of a structure as a result of its own weight and other actions
3.19
strength
mechanical property of a material indicating its ability to resist actions, usually given in units of stress
Note 1 to entry: See ISO 19902.
3.20
undrained condition
condition whereby the applied stresses and stress changes are supported by both the soil skeleton and
the pore fluid and do not cause a change in volume
[SOURCE: ISO 19901-8:2014, 3.42]
4 Symbols and abbreviated terms
4.1 General
Commonly used symbols are listed in 4.2 to 4.5; other symbols are defined in the text following the
applicable formula. It should be noted that symbols can have different meanings between formulae.
4.2 Symbols for shallow foundations design
A actual (cross-sectional plan) foundation area
A′ effective foundation area depending on eccentricity of actions
A vertical projected area of the foundation in the direction of sliding
h
A projected area of skirt tip
p
4 © ISO 2016 – All rights reserved

ISO 19901-4:2016(E)
A side surface area of skirt embedded at a particular penetration depth
s
A idealized rectangular foundation area, for irregular foundation shapes
idealized
b , b , b bearing capacity correction factors related to foundation base inclination
c q γ
B minimum lateral foundation dimension (also foundation width)
B′ minimum effective lateral foundation dimension (also foundation effective width)
C compression index of soil over loading range considered
d , d , d bearing capacity correction factors related to foundation embedment depth
c q γ
D foundation diameter (for circular foundations)
D depth below seafloor to foundation base level
b
e eccentricity of action
e initial void ratio of the soil
e eccentricity of action in coordinate direction 1
e eccentricity of action in coordinate direction 2
f unit skin friction resistance along foundation skirts during installation
F bearing capacity correction factor to account for undrained shear strength heterogeneity
g , g , g correction factors related to seafloor inclination
c q γ
G elastic shear modulus of soil
h soil layer thickness
H horizontal action
H horizontal action on effective area component of the base
b
H design value of resistance to pure sliding
d
ΔH horizontal soil resistance due to active and passive earth pressures on foundation skirts
d
H ultimate horizontal capacity in yield surface design method
ult
i , i , i bearing capacity correction factors related to foundation action inclination
c q γ
K , K , K correction factors that account for inclined actions, foundation shape, depth of embedment,
c q γ
inclination of base, and inclination of the seafloor
K coefficient of passive earth pressure
p
K drained horizontal soil reaction coefficient
rd
K un
...