EN 1997-2:2024

SLOVENSKI STANDARD
oSIST prEN 1997-2:2022
01-december-2022
Evrokod 7 - Geotehnično projektiranje - 2. del: Lastnosti tal
Eurocode 7 - Geotechnical design - Part 2: Ground properties
Eurocode 7: Entwurf, Berechnung und Bemessung in der Geotechnik - Teil 2: Erkundung
und Untersuchung des Baugrunds
Eurocode 7 - Calcul géotechnique - Partie 2 : Propriétés des terrains
Ta slovenski standard je istoveten z: prEN 1997-2
ICS:
91.010.30 Tehnični vidiki Technical aspects
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
oSIST prEN 1997-2:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 1997-2:2022
oSIST prEN 1997-2:2022
DRAFT
EUROPEAN STANDARD
prEN 1997-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2022
ICS 91.010.30; 93.020 Will supersede EN 1997-2:2007
English Version
Eurocode 7 - Geotechnical design - Part 2: Ground
properties
Eurocode 7: Entwurf, Berechnung und Bemessung in
der Geotechnik - Teil 2: Erkundung und Untersuchung
des Baugrunds
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 250.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1997-2:2022 E
worldwide for CEN national Members.

oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
Contents Page
European foreword . 4
0 Introduction . 5
1 Scope . 7
1.1 Scope of prEN 1997-2 . 7
1.2 Assumptions . 7
2 Normative references . 7
3 Terms, definitions, and symbols . 8
3.1 Terms and definitions . 8
3.2 Symbols and abbreviations .16
4 Ground Model .21
4.1 General .21
4.2 Derived values .21
5 Ground investigation .22
5.1 General .22
5.2 Contents of ground investigation .23
5.3 Ground investigation techniques .25
5.4 Planning of preliminary and design investigations .27
6 Description and classification of the ground .31
6.1 General .31
6.2 Discontinuities and weathered zones.31
7 State, physical, and chemical properties .32
7.1 State properties .32
7.2 Physical properties .36
7.3 Chemical properties .41
8 Strength .45
8.1 Strength envelopes and parameters for soils and rocks .45
8.2 Soil strength .48
8.3 Rock strength .51
8.4 Interface strengths .54
9 Stiffness, compressibility and consolidation .54
9.1 Ground stiffness .54
9.2 Ground compressibility and consolidation .59
10 Cyclic, dynamic, and seismic properties .62
10.1 General .62
10.2 Measurement of cyclic response.62
10.3 Secant modulus and damping ratio curves .63
10.4 Very small strain moduli and wave velocities .64
10.5 Excess pore water pressure .66
10.6 Cyclic shear strength .67
10.7 Additional parameters for seismic site response evaluation .68
11 Groundwater and geohydraulic properties .68
11.1 General .68
11.2 Groundwater pressure and pressure head .69
11.3 Geohydraulic properties .71
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prEN 1997-2:2022 (E)
12 Geothermal properties . 73
12.1 General . 73
12.2 Frost susceptibility . 74
12.3 Thermal conductivity . 75
12.4 Heat capacity . 75
12.5 Thermal diffusivity . 75
12.6 Thermal linear expansion . 75
12.7 Direct determination of geothermal properties . 75
13 Reporting . 76
13.1 Ground Investigation Report . 76
Annex A (normative) Ground Investigation Report . 77
Annex B (informative)  Suitability and applicability of test methods . 80
Annex C (informative)  Desk study and site inspection . 97
Annex D (informative)  Information to be obtained from ground investigation . 103
Annex E (informative) Methods for determining density index and strength properties . 106
Annex F (informative) Methods for determining stiffness and consolidation properties of
soils . 112
Annex G (informative) Indirect methods for determining cyclic, dynamic, and seismic
properties of soils . 118
Bibliography . 123

oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
European foreword
This document (prEN 1997-2:2022) has been prepared by Technical Committee CEN/TC 250 “Structural
Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible for all Structural
Eurocodes and has been assigned responsibility for structural and geotechnical design matters by CEN.
This document will supersede EN 1997-2:2007.
The first generation of EN Eurocodes was published between 2002 and 2007. This document forms part
of the second generation of the Eurocodes, which have been prepared under Mandate M/515 issued to
CEN by the European Commission and the European Free Trade Association.
The Eurocodes have been drafted to be used in conjunction with relevant execution, material, product
and test standards, and to identify requirements for execution, materials, products and testing that are
relied upon by the Eurocodes.
The Eurocodes recognize the responsibility of each Member State and have safeguarded their right to
determine values related to regulatory safety matters at national level through the use of National
Annexes.
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
0 Introduction
0.1 Introduction to the Eurocodes
The Structural Eurocodes comprise the following standards generally consisting of a number of Parts:
— EN 1990, Eurocode: Basis of structural and geotechnical design
— EN 1991, Eurocode 1: Actions on structures
— EN 1992, Eurocode 2: Design of concrete structures
— EN 1993, Eurocode 3: Design of steel structures
— EN 1994, Eurocode 4: Design of composite steel and concrete structures
— EN 1995, Eurocode 5: Design of timber structures
— EN 1996, Eurocode 6: Design of masonry structures
— EN 1997, Eurocode 7: Geotechnical design
— EN 1998, Eurocode 8: Design of structures for earthquake resistance
— EN 1999, Eurocode 9: Design of aluminium structures
— New parts are under development, e.g. Eurocode for design of structural glass
The Eurocodes are intended for use by designers, clients, manufacturers, constructors, relevant
authorities (in exercising their duties in accordance with national or international regulations),
educators, software developers, and committees drafting standards for related product, testing and
execution standards.
NOTE Some aspects of design are most appropriately specified by relevant authorities or, where not specified,
can be agreed on a project-specific basis between relevant parties such as designers and clients. The Eurocodes
identify such aspects making explicit reference to relevant authorities and relevant parties.
0.2 Introduction to EN 1997 Eurocode 7
EN 1997 consists of a number of parts:
— EN 1997-1, Geotechnical design – Part 1: General rules
— EN 1997-2, Geotechnical design – Part 2: Ground properties
— EN 1997-3, Geotechnical design – Part 3: Geotechnical structures
EN 1997 standards establish additional principles and requirements to those given in EN 1990 for the
safety, serviceability, robustness, and durability of geotechnical structures.
EN 1997 standards are intended to be used in conjunction with the other Eurocodes for the design of
geotechnical structures, including temporary geotechnical structures.
Design and verification in EN 1997 (all parts) are based on the partial factor method or other reliability-
based methods, prescriptive rules, testing, or the observational method.
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prEN 1997-2:2022 (E)
0.3 Introduction to prEN 1997-2
prEN 1997-2 establishes rules for obtaining information about the ground at a site, as needed for the
design and execution of geotechnical structures, including temporary geotechnical structures.
0.4 Verbal forms used in the Eurocodes
The verb “shall" expresses a requirement strictly to be followed and from which no deviation is permitted
in order to comply with the Eurocodes.
The verb “should” expresses a highly recommended choice or course of action. Subject to national
regulation and/or any relevant contractual provisions, alternative approaches could be used/adopted
where technically justified.
The verb “may" expresses a course of action permissible within the limits of the Eurocodes.
The verb “can" expresses possibility and capability; it is used for statements of fact and clarification of
concepts.
0.5 National annex for prEN 1997-2
National choice is allowed in this standard where explicitly stated within notes. National choice includes
the selection of values for Nationally Determined Parameters (NDPs).
The national standard implementing prEN 1997-2 can have a National Annex containing all national
choices to be used for the design of buildings and civil engineering works to be constructed in the relevant
country.
When no national choice is given, the default choice given in this standard is to be used.
When no national choice is made and no default is given in this standard, the choice can be specified by a
relevant authority or, where not specified, agreed for a specific project by appropriate parties.
National choice is allowed in prEN 1997-2:2022 through the following clauses:
5.4.3(2) 5.4.3(3)
National choice is allowed in prEN 1997-2 on the application of the following informative annexes:
Annex B Annex C Annex D Annex E
Annex F Annex G
The National Annex can contain, directly or by reference, non-contradictory complementary information
for ease of implementation, provided it does not alter any provisions of the Eurocodes.
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
1 Scope
1.1 Scope of prEN 1997-2
(1) This document provides rules for determining ground properties for the design and verification of
geotechnical structures.
(2) This document covers guidance for planning ground investigations, collecting information about
ground properties and groundwater conditions, and preparation of the Ground Model.
(3) This document covers guidance for the selection of field investigation and laboratory test methods to
obtain derived values of ground properties.
(4) This document covers guidance on the presentation of the results of ground investigation, including
derived values of ground properties, in the Ground Investigation Report.
1.2 Assumptions
(1) The provisions in prEN 1997-2:2022 are based on the assumptions given in prEN 1990:2021 and
prEN 1997-1:2022.
(2) This document is intended to be used in conjunction with prEN 1997-1:2022, which provides general
rules for design and verification of all geotechnical structures.
(3) This document is intended to be used in conjunction with prEN 1997-3:2022, which provides specific
rules for design and verification of certain types of geotechnical structures.
(4) This document is intended to be used in conjunction with prEN 1998-1-1 which provides the
requirements for the ground properties needed to define the seismic action.
(5) This document is intended to be used in conjunction with prEN 1998-5 which provides rules for the
design of geotechnical structures in seismic regions.
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.
NOTE See the Bibliography for a list of other documents cited that are not normative references, including
those referenced as recommendations (i.e. in ‘should’ clauses), permissions (‘may’ clauses), possibilities ('can'
clauses), and in notes.
prEN 1990:2021, Eurocode - Basis of structural and geotechnical design
prEN 1997-1:2022, Eurocode 7: Geotechnical design - Part 1: General rules
prEN 1998-1-1, Eurocode 8 - Design of structures for earthquake resistance - Part 1-1: General rules and
seismic action
prEN 1998-5, Eurocode 8 - Design of structures for earthquake resistance - Part 5: Geotechnical aspects,
foundations, retaining and underground structures
EN ISO 22475-1, Geotechnical investigation and testing - Sampling methods and groundwater
measurements - Part 1: Technical principles for the sampling of soil, rock and groundwater (ISO 22475-1)
EN ISO 22476-1, Geotechnical investigation and testing - Field testing - Part 1: Electrical cone and
piezocone penetration text (ISO 22476-1)
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prEN 1997-2:2022 (E)
3 Terms, definitions, and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in prEN 1990:2021 and
prEN 1997-1:2022 and the following apply.
3.1.1 Common terms used in prEN 1997-2
3.1.1.1
site
surface area or underground space where construction work or other development is undertaken
3.1.1.2
anthropogenic ground
materials placed by human activity
3.1.1.3
rockhead
boundary between soil and rock
Note 1 to entry: Rockhead can either be a geological boundary between in-situ (usually weathered) and
transported materials or an engineering boundary between materials that behave as soil and those that behave as
rock.
3.1.2 Terms relating to the Ground Model
3.1.2.1
state property
ground property that can change over time, such as mass density, water content and saturation, density
index, or stress state
3.1.2.2
measured value of a ground property
value of a ground property recorded during a test
3.1.3 Terms relating to content of ground investigation
3.1.3.1
ground investigation
use of non-intrusive and intrusive methods to investigate the ground and groundwater conditions
beneath or around the site or zone of influence
3.1.3.2
ground investigation location
location (point, line, or area) on the site where the ground is examined and investigated by intrusive or
non-intrusive methods
3.1.3.3
low-rise structure
warehouse sheds, factory buildings, or residential buildings up to three storeys high
3.1.3.4
high-rise structure
buildings and structures greater than three storeys high, including chimneys and towers
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3.1.3.5
site inspection
observation and recording of features relevant to the surface and sub-surface conditions and any
exposures of the ground, existing infrastructure or environment
Note 1 to entry: The inspection normally extends beyond the site boundaries.
3.1.3.6
sample
defined amount of rock, soil, or groundwater recovered from recorded depth
[SOURCE: EN ISO 22475-1:2021]
3.1.3.7
specimen
part of the sample taken for laboratory testing
3.1.3.8
sample quality class
quality class of the sample based on its degree of disturbance according to sampling technique
[SOURCE: EN ISO 22475-1:2021]
3.1.3.9
disturbance factor
disturbance of the rock mass
3.1.3.10
mapping
process of physically going out into the field and recording information from the ground at the surface or
from excavations and exposures
3.1.3.11
geological mapping
mapping to record and describe geological information and features observed in the field
Note 1 to entry: Description covers features such as morphology, lithology, hydrogeology, weathering, and any
visible geological structure.
3.1.3.12
geotechnical mapping
geological mapping with the addition of ground classification in terms of quality indexes and of
geometrical features of discontinuities
Note 1 to entry: Classification covers parameters such as rock quality designation, rock mass rating, joint sets,
alteration and weathering numbers, joint wall roughness, and technical ground behaviour.
3.1.4 Terms relating to chemical, physical, and state properties
3.1.4.1
classification
definition of material groups and classes and assigning of materials to groups and classes with similar
properties
[SOURCE: EN 16907-2:2018, 3.1.2, modified – deleted “for earthworks”.]
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3.1.4.2
very coarse soil
soil with particle sizes larger than 63 mm
[SOURCE: EN ISO 14688-1:2018]
3.1.4.3
coarse soil
soil with particle sizes between 0,063 and 63 mm
[SOURCE: EN ISO 14688-1:2018]
3.1.4.4
fine soil
soil with particle sizes smaller than 0,063 mm
[SOURCE: EN ISO 14688-1:2018]
3.1.4.5
density index
ratio of the difference between the maximum void ratio and the observed void ratio to the difference
between maximum and minimum void ratios
3.1.4.6
relative density
synonym for ‘density index’
3.1.4.7
consistency (Atterberg) limits
collective name for liquid, plastic, and shrinkage limits of soil
3.1.4.8
liquid limit
water content of soil at which a fine soil passes from the liquid to the plastic condition, as determined by
the liquid limit test
[SOURCE: EN ISO 14688-2:2018]
3.1.4.9
plastic limit
water content of soil at which a fine soil passes from the plastic to the semi-solid condition, as determined
by the plastic limit test
[SOURCE: EN ISO 14688-2:2018]
3.1.4.10
shrinkage limit
water content of soil below which loss of water does not result in volume reduction
3.1.4.11
activity index
ratio of the plasticity index and the clay fraction that is finer than two microns
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3.1.5 Terms relating to strength
3.1.5.1
shear strength envelope
expression that identifies stress combinations that produce material failure
3.1.5.2
shear strength parameters
material parameters appearing in the expression of shear strength envelopes
3.1.5.3
shear strength in effective stresses
shear strength obtained from an envelope defined in terms of effective stress
3.1.5.4
peak shear strength
upper limit of the shear strength observed in a test
3.1.5.5
critical state shear strength
shear strength observed when shearing continues without change in either volume or pore water
pressure
3.1.5.6
residual shear strength
lower limit of the shear strength of a fine soil reached after extensive shearing and particle re-orientation
or lower limit of the shear strength reached after extensive shearing of discontinuities
3.1.5.7
undrained shear strength
shear strength of water saturated soils obtained from an envelope defined in terms of total stress
3.1.5.8
peak undrained shear strength
upper limit of the undrained shear strength for undisturbed soil
3.1.5.9
remoulded undrained shear strength
undrained shear strength for totally remoulded soil
3.1.5.10
sensitivity
ratio between peak and remoulded undrained shear strengths
3.1.5.11
crack initiation stress
stress level at which pre-existing cracks (rock material) or discontinuities (rock mass) initiate growth
3.1.5.12
crack damage stress
stress level at which unstable growth of cracks (rock material) or discontinuities (rock mass) occurs
3.1.5.13
Geological Strength Index
index used to estimate rock mass strength and rock mass deformation modulus
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prEN 1997-2:2022 (E)
3.1.5.14
Joint Roughness Coefficient
number characterizing the roughness of discontinuities
3.1.5.15
joint wall compressive strength
compressive strength of a discontinuity adjusted for weathering, size, width, infill and scale
3.1.5.16
rock mass strength
strength resulting from the combination of the structural and material properties of the rock mass
3.1.5.17
flexural strength
strength of the rock material from a flexure test
[SOURCE: ASTM C880-98]
3.1.6 Terms relating to stiffness and consolidation
3.1.6.1
elastic modulus
ratio of stress increase to the corresponding increase in strain in the stress-strain relationship as shown
in Figure 3.1
Key
X strain c Esec orGsec
Y shear stress d Ecyc or Gcyc
a E or G e E or G
0 0 tan tan
b E or G
50 50
Figure 3.1 — Definition of modulus on stress-strain curve
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3.1.6.2
bulk modulus
ratio between mean stress increase to a corresponding decrease in volumetric strain
3.1.6.3
shear modulus
ratio of shear stress increase to a corresponding increase in shear strain, as shown in Figure 3.1
3.1.6.4
secant modulus
ratio between stress and the corresponding strain accumulated from an initial reference state, as defined
by Figure 3.1
3.1.6.5
tangent modulus
ratio between small increments of stress and strain from a given reference state, as shown in Figure 3.1
3.1.6.6
very small strain elastic modulus
-5
value of the elastic modulus at strains < 10
3.1.6.7
very small strain Poisson's ratio
-5
value of Poisson's ratio at strains < 10
3.1.6.8
oedometer (one dimensional) modulus
ratio of the variation of a principal stress by the linear strain obtained in the same direction, with the
other principal strains equal to zero
Note 1 to entry: Also known as the 'constrained modulus'.
3.1.6.9
swelling
ground volume expansion caused by physicochemical processes or by the ingress of water
3.1.6.10
undrained modulus
elastic modulus for undrained conditions
3.1.7 Terms relating to cyclic, dynamic, and seismic properties
3.1.7.1
compressional wave velocity
velocity of propagation of a compressional (primary) wave in a medium
3.1.7.2
cyclic liquefaction
transition of soil behaviour from solid-like to liquid-like due to cyclic or seismic actions
3.1.7.3
cyclic modulus
slope of the line connecting the two points of reversal in cyclic loading as shown in Figure 3.1
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prEN 1997-2:2022 (E)
3.1.7.4
cyclic shear strength
maximum value of cyclic shear stress that can be sustained for a given number of cycles without
exceeding a given strain threshold
3.1.7.5
cyclic strain
maximum strain attained or imposed during the application of cyclic actions
3.1.7.6
cyclic stress
maximum stress attained or imposed during to the application of cyclic actions
3.1.7.7
damping ratio
ratio between the energy dissipated in a cyclically loaded system and the corresponding elastic energy of
deformation based on hysteresis loops of stress vs strain
3.1.7.8
cyclic degradation
deterioration of ground properties due to repeated load cycles (similar to fatigue in structural members)
3.1.7.9
fundamental frequency
lowest value of the frequency associated with relative maximum amplification of the seismic ground
motion
3.1.7.10
post-cyclic strength
available strength after the application of a given number of stress cycles
3.1.7.11
post-cyclic creep
deformation associated with average constant loads after the application of a given number of stress
cycles
3.1.7.12
seismic bedrock
reference formation identified by a shear wave velocity greater than 800 m/s
[SOURCE: prEN 1998-1-1:2022]
3.1.7.13
shear wave velocity
velocity of propagation of a shear wave in a medium
3.1.8 Terms relating to groundwater and geohydraulic properties
3.1.8.1
aquitard
confining layer that retards, but does not prevent, the flow of water to or from an adjacent aquifer
[SOURCE: EN ISO 22475-1:2021]
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3.1.8.2
joint water pressure
pressure of the water in the joints or discontinuities of ground
3.1.8.3
pressure head
ratio of the pore water/joint water pressure and the weight density of water above a point
[SOURCE: EN ISO 18674-4:2020]
3.1.8.4
piezometer
field instrument system for measuring pore or joint water pressure or piezometric level, at the measuring
point
Note 1 to entry: The system is either an open or closed piezometric system.
[SOURCE: EN ISO 18674-4:2020, 3.1, modified]
3.1.8.5
open system
field instrument system in which the fluid is in direct contact with the atmosphere and the piezometric
level at the measuring point is measured
Note 1 to entry: Also known as an 'open piezometric system'.
[SOURCE: EN ISO 18674-4:2020]
3.1.8.6
closed system
measuring system in which the reservoir is not in direct contact with the atmosphere and in which the
pressure in the fluid is measured by a pressure measuring device
Note 1 to entry: Also known as a 'closed piezometric system'.
[SOURCE: EN ISO 18674-4:2020]
3.1.8.7
hydraulic conductivity
ratio of the average velocity of a fluid through a cross-sectional area (Darcy's velocity) to the applied
hydraulic gradient
Note 1 to entry: Hydraulic conductivity can be anisotropic.
3.1.8.8
absolute permeability
property that quantifies the ability of porous ground to permit the flow of fluids through its pore spaces
Note 1 to entry: Also known as intrinsic permeability or specific permeability. The terms 'hydraulic conductivity'
and 'absolute permeability' are interchangeable if the ground is fully saturated.
3.1.8.9
transmissivity
rate at which water passes through a unit width of an aquifer under unit hydraulic gradient
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3.1.9 Terms relating to geothermal properties
3.1.9.1
thermal conductivity
ratio of the thermal flux through a cross-sectional area (Fourier's law) to the applied thermal gradient
3.1.9.2
heat capacity or specific heat capacity
capacity of a material to store thermal energy
3.1.9.3
thermal diffusivity
ratio of the thermal conductivity to the specific heat capacity
3.2 Symbols and abbreviations
For the purposes of this document, the symbols given in prEN 1997-1:2022 and the following apply.
3.2.1 Latin upper case letters
B pore water pressure coefficient
C thermal capacity per unit volume
C compression index
c
C coefficient of curvature
C,PSD
C non-dimensional coefficient of correlation
i
C coefficient of uniformity
U,PSD
C coefficient of secondary compression
α
D disturbance factor for rock mass
D particle size that n % by weight are smaller than
n
E Young's modulus from a borehole jack test according to EN ISO 22476-7
BJT
E cyclic Young's modulus
cyc
E Young's modulus from a flat dilatometer test according to EN ISO 22476-11
DMT
E Young's modulus from a full displacement pressuremeter test according to EN ISO 22476-8
FDP
E Young's modulus of intact rock
i
E Young's modulus from a Ménard pressuremeter test according to EN ISO 22476-4
M
E Young's modulus from an oedometer test according to EN ISO 17892-5
OED
E Young's modulus from a pre-bored pressuremeter test according to EN ISO 22476-5
PBP
E Young's modulus from a plate loading test
PLT
E Young's modulus of rock mass
rm
E Young's modulus of soil
s
E Young's modulus from a self-boring pressuremeter test according to EN ISO 22476-6
SBP
E secant Young's modulus
sec
E tangent Young's modulus
tan
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E undrained Young's modulus
u
G shear modulus at very small strain
G shear modulus from a Ménard pre-bored pressuremeter test according to EN ISO 22476-4
M
G shear modulus from a pre-bored pressuremeter test according to EN ISO 22476-5
PBP
G shear modulus from a self-boring pressuremeter test according to EN ISO 22476-6
SBP
H depth of the bedrock formation identified by a shear wave velocity vs greater than 800 m/s
I activity index
A
I density index of coarse soil
D
I fracture spacing
f
I liquidity index of fine soil according to EN ISO 17892-12
L
I plasticity index of fine soil according to EN ISO 17892-12
P
K bulk modulus
bulk
K DMT horizontal stress index as per EN ISO 22476-11
D
K at-rest earth pressure coefficient
K calibration factor for PMT test results
PMT
K rock creep index
r
L length of test section in the thickness of aquifer
N SPT blow count normalized for energy as per EN ISO 22476-3
(N ) SPT blow count normalized for overburden pressure and energy as per EN ISO 22476-3
1 60
Q coefficient that depends on the crushability of the material
T transmissivity
V equivalent value of the shear wave velocity of the soil column above the depth of the bedrock
S,H800
formation
3.2.2 Latin lower case letters
a non-dimensional material parameter in Hoek-Brown envelope
c′ effective cohesion measured at a condition X (p for peak, cs for critical state, r for residual) by a
X,Y
specific test Y (UCT, UU, TX, FVT, etc.)
c coefficient of horizontal consolidation
h
c peak undrained shear strength
u,p
c remoulded undrained shear strength
u,rmd
c undrained shear strength measured at a condition X (p for peak, cs for critical state, r for
u,X,Y
residual) by a specific test Y (UCT, UU, TX, FVT, etc.)
e void ratio of soil
e maximum void ratio of soil
max
e minimum void ratio of soil
min
f fundamental frequency of a soil deposit
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
f soil property function defining the relationship between shear strength and soil suction
h pressure head
w
k absolute permeability
m coefficient that depends on the relevant shear mode to failure
m non-dimensional material parameter for rock mass in the Hoek-Brown envelope
b
m non-dimensional material parameter for rock material in the Hoek-Brown envelope
i
m one dimensional compressibility
v
p′ mean principal effective stress
p corrected pressure at the origin of the pressuremeter modulus pressure range (see EN ISO
22476-4)
p atmospheric air pressure
a
p limit pressure from Ménard pressuremeter test according to EN ISO 22476-4
LM
p reference pressure usually equal to 100 kPa
ref
q cone tip resistance measured as per EN ISO 22476-1
c
q net cone resistance (= q – σ )
n t v0
q corrected cone resistance as per EN ISO 22476-1
t
s non-dimensional material parameter for Hoek-Brown envelope
v compressional wave velocity
P
v shear wave velocity
S
w water content
w liquid limit of soil
L
w plastic limit of soil
P
w shrinkage limit of soil
S
3.2.3 Greek upper case letters
Δu excess pore water pressure measured at the gap between cone tip and friction sleeve as per EN
ISO 22476-1
3.2.4 Greek lower case letters
γ shear strain
γw weight density of groundwater
δ horizontal incremental displacement of a specimen in direct shear
x
δ vertical incremental displacement of a specimen in direct shear
z
ε strain
η dynamic viscosity of a fluid
κ thermal diffusivity
λ thermal conductivity
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
ν Poisson’s ratio
ν Poisson’s ratio at very small strain
ρ bulk mass density
σ normal stress
σ′ effective normal stress
σ uniaxial compressive strength of intact rock
ci
σ flexural strength of rock material
fl
σ′ in-situ horizontal effective stress
h0
σ normal stress acting on a discontinuity
n
σ′ preconsolidation pressure
p
σ tensile strength of soil or rock
t
σ total vertical stress
v
σ in-situ vertical total stress
v0
σ′ in-situ vertical effective stress
v0
σ major principal stress
σ minor principal stress
τ shear stress
τ peak shear strength of discontinuity
p
φ angle of friction
φ′ angle of effective friction
φ base angle of friction of a rock surface
b
φ′ angle of peak effective friction
p
φ′ angle of effective friction measured at a condition X (p for peak, cs for critical state, r for
X
residual)
φ′ effective stress angle of internal friction measured at a condition X (p for peak, cs for critical
X,Y
state, r for residual) by a specific test Y (UCT, UU, TX, FVT, etc.)
3.2.5 Abbreviations
BDP Borehole Dynamic Penetration (test)
BE bender element
BJT Borehole Jack Test
BST Borehole Shear Test
CDSS Cyclic Direct Simple Shear
CPT Cone Penetration Test
CPTU Cone Penetration Test with pore water pressure measurement (piezocone test)
CRS constant rate of strain
CTS cyclic torsional shear
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
CTxT cyclic triaxial test
DMT Flat Dilatometer Test (also known as Marchetti Dilatometer Test)
DP Dynamic Penetration (Test)
DSS direct simple shear
DST Direct Shear Test
FDP full displacement pressuremeter
FDT Flexible Dilatometer Test
FVT Field Vane Test
GIR Ground Investigation Report
GSI Geological Strength Index
IL incremental loading oedometer test
IST interface shear test
JCS joint compressive strength of a discontinuity
JRC Joint Roughness Coefficient
MPM Ménard pressuremeter
MQC minimum quality class of sample suitable for a test (see Annex F)
MR modulus ratio
MWD measuring while drilling
OCR over-consolidation ratio
OMR organic matter content
OED oedometer test
PLT Plate Loading Test
PBP pre-bored pressuremeter
PMT Pressuremeter Test
RC resonant column
RQD Rock Quality Designation
SBP self-boring pressuremeter
SCR Solid Core Recovery
SPT Standard Penetration Test
TCR Total Core Recovery
TxT triaxial test
UCS Unconfined Compressive Strength
UCT Unconfined Compression Test
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
4 Ground Model
4.1 General
(1) A Ground Model shall comprise the geological, hydrogeological, and geotechnical conditions at the
site, based on the ground investigation results.
NOTE 1 Geological conditions include, for example, the description of the site geomorphology, the lithology of
the geotechnical units, the potential presence and level of a rockhead, geometrical and geotechnical properties of
discontinuities and weathered zones.
NOTE 2 Hydrogeological conditions address surface, groundwater, and piezometric levels, including their
potential variation with time, potential water flows and the presence of other fluids or gases affecting the site.
NOTE 3 Geotechnical conditions include, for example, the disposition of the geotechnical units and the
mechanical behaviour of the ground described by the properties of the geotechnical units.
(2) Variability and uncertainty of geological, hydrogeological and geotechnical conditions and properties
shall be included in the Ground Model.
(3) The detail and the extent of the Ground Model shall be consistent with the Geotechnical Category and
the zone of influence of the structure.
NOTE Guidance on Geotechnical Category and zone of influence is given in prEN 1997-1:2022, 4.1.2.
(4) The Ground Model shall be progressively developed and updated based on potential new information.
(5) The Ground Model shall include the derived values of relevant ground properties for all geotechnical
units encountered in the zone of influence.
NOTE Guidance on derived values are given in 4.2.
(6) The Ground Model shall be documented in the Ground Investigation Report.
NOTE 1 The Ground Model is the main output of the Ground Investigation.
NOTE 2 The Ground Model forms the basis for development of the Geotechnical Design Model (see
prEN 1997-1:2022, 4.2.3).
4.2 Derived values
(1) Derived values of the properties of a geotechnical unit shall be established from data gathered during
the desk study, site inspection, preliminary and design investigations, and monitoring of the ground and
structures.
(2) Empirical correlations and theories used to obtain the derived values shall be documented in the
Ground Investigation Report.
(3) The Ground Investigation Report shall record whether empirical correlations and theories used in
parameter derivation are intended to provide average, superior, or inferior values.
(4) The information given for each correlation should specify either directly or through reference:
— the materials to which they apply, specified by their classification according to EN ISO 14688-2 and
EN ISO 14689, or their physical and chemical properties;
— the database that supports the correlation;
— the estimated transformation errors.
oSIST prEN 1997-2:2022
prEN 1997-2:2022 (E)
(5) Site-specific data should be used to support generic correlations.
NOTE Site specific data generally results in smaller correlation errors.
(6) Der
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