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En 1997
1. EUROCODES
Background and Applications
“Dissemination of information for training” workshop
18-20 February 2008
Brussels
EN 1997
Eurocode 7: Geotechnical design
Organised by
European Commission: DG Enterprise and Industry, Joint Research Centre
with the support of
CEN/TC250, CEN Management Centre and Member States
2.
3. Wednesday, February 20 – Palais des Académies
EN 1997 - Eurocode 7: Geotechnical design
Bordet room
9:00-10:00 General presentation of EC 7
Geotechnical design part 1 General
rules
R. Frank
Ecole Nationale des Ponts et
Chaussées
10:00-11:00 Section 2: Basis of geotechnical design B. Schuppener
Bundesanstalt für Wasserbau
11:00-11:15 Coffee
11:15-12:15 Section 3 Geotechnical data and 6
Spread foundations
T. Orr
Trinity College Dublin
12:15-14:00 Lunch
14:00-15:00 Section 7 Pile foundations R. Frank
Ecole Nationale des Ponts et
Chaussées
15:00-16:00 Section 8 Anchorages and Section 9
Retaining structures
B. Simpson
Arup
16:00-16:15 Coffee
16:15-17:15 Section 10 Hydraulic failure, Section 11
Overall stability and Section 12
Embankments
T. Orr
Trinity College Dublin
17:15-18:15 Eurocode 7 part 2: Ground investigation
and testing
B. Schuppener
Bundesanstalt für Wasserbau
All workshop material will be available at
http://eurocodes.jrc.ec.europa.eu
7. Brussels, 18-20 February 2008 – Dissemination of information workshop 1
EUROCODES
Background and Applications
General presentation of EUROCODE 7
‘Geotechnical design’
Workshop “Eurocodes: background and applications”
Brussels, 18-20 February 2008
Roger FRANK, Professor
Ecole nationale des ponts et chaussées, Paris
Brussels, 18-20 February 2008 – Dissemination of information workshop 2
EUROCODES
Background and Applications
1. Introduction
2. Contents of Eurocode 7 - Parts 1 & 2
3. Some aspects of Eurocode 7-1
Characteristic values
ULS Design Approaches
SLS –Serviceability limit states
Brussels, 18-20 February 2008 – Dissemination of information workshop 3
EUROCODES
Background and Applications
EN 1990EN 1990
ENEN 19911991
EN 1992EN 1992 EN 1993EN 1993 EN 1994EN 1994
EN 1995EN 1995 EN 1996EN 1996 EN 1999EN 1999
Basis of StructuralBasis of Structural
designdesign
Actions onActions on
structuresstructures
««MaterialMaterial »»
resistanceresistance
EN 1997EN 1997 EN 1998EN 1998 GeotechnicalGeotechnical
andand seismicseismic
designdesign
STRUCTURAL EUROCODES
Brussels, 18-20 February 2008 – Dissemination of information workshop 4
EUROCODES
Background and Applications
EN 1997EN 1997--1 (2004)1 (2004) :: Part 1Part 1 -- General rulesGeneral rules
EN 1997EN 1997--2 (2007)2 (2007) :: Part 2Part 2 -- Ground investigationGround investigation
and testingand testing
Eurocode 7 – Geotechnical design
Brussels, 18-20 February 2008 – Dissemination of information workshop 5
EUROCODES
Background and Applications
2. Contents of Eurocode 7 –
Parts 1 & 2
Brussels, 18-20 February 2008 – Dissemination of information workshop 6
EUROCODES
Background and Applications Contents of Part 1 (EN 1997-1)
Section 1 General
Section 2 Basis of geotechnical
design
Section 3 Geotechnical data
Section 4 Supervision of
construction, monitoring
and maintenance
Section 5 Fill, dewatering, ground
improvement and
reinforcement
8. Brussels, 18-20 February 2008 – Dissemination of information workshop 7
EUROCODES
Background and Applications
Section 6 Spread foundations
Section 7 Pile foundations
Section 8 Anchorages
Section 9 Retaining structures
Section 10 Hydraulic failure
Section 11 Site stability
Section 12 Embankments
Contents of Part 1 (cntd)
Brussels, 18-20 February 2008 – Dissemination of information workshop 8
EUROCODES
Background and Applications
Informative annexes
Annexes D & E : Bearing capacity of
foundations
R/A' = c' × Nc × bc × sc × ic +
q' × Nq × bq × sq × iq +
0,5 × γ' × B '× Nγ × bγ × sγ × iγ
R /A' = σv0 + k × p*le
Annex C
Active
earth
pressure
Annex C – Passive earth
pressure
Annex F : Settlement of foundations
s = p × b × f / Em
Brussels, 18-20 February 2008 – Dissemination of information workshop 9
EUROCODES
Background and Applications
Part 2 (EN 1997-2 ): Geotechnical design -
Ground investigation and testing
Laboratory and field tests :
* essential requirements for the equipment and
tests procedures
* essential requirements for the reporting and
the presentation of results
* interpretation of test results and derived values
They are NOT test standards see TC 341
Brussels, 18-20 February 2008 – Dissemination of information workshop 10
EUROCODES
Background and Applications Contents of Part 2 (EN 1997-2)
Section 1 General
Section 2 Planning and reporting
of ground investigations
Section 3 Drilling, sampling and
gw measurements
Section 4 Field tests in soils and
rocks
Section 5 Laboratory tests on soils
and rocks
Section 6 Ground investigation
report
> Also a number of Informative annexesInformative annexes
Brussels, 18-20 February 2008 – Dissemination of information workshop 11
EUROCODES
Background and Applications
3. Some aspects of Eurocode 7-1
Characteristic values and design values
ULS Design ApproachesULS Design Approaches
SLS and deformations of structuresSLS and deformations of structures
Brussels, 18-20 February 2008 – Dissemination of information workshop 12
EUROCODES
Background and Applications
Type of test
F= field L= laboratory
Correlations
Test results and
derived values
1 2 3 4
F 1 F 2 L 1 L 2
C1
Cautious selection
Geotechnical model and characteristic
value of geotechnical properties
Design values of geotechnical
properties
Application of
partial factors
Information
from other
sources on
the site, the
soils and
rocks and
the project
EN 1997 -1
EN 1997 -2
C1 C2
Geotechnical properties
9. Brussels, 18-20 February 2008 – Dissemination of information workshop 13
EUROCODES
Background and Applications
Characteristic value
of geotechnical parameters
P The characteristic valuecharacteristic value of a geotechnical
parameter shall be selected as a cautious
estimate of the value affecting the occurrence of
the limit state.
If statistical methods are used, the characteristic
value should be derived such that the calculated
probability of a worse value governing the
occurrence of the limit state under consideration is
not greater than 5%.
Brussels, 18-20 February 2008 – Dissemination of information workshop 14
EUROCODES
Background and Applications
Design value of a parameter : Xd = Xk / γM
Design values of actions and resistances
fulfilling for STR/GEO ULS : Ed ≤ Rd
Ed = E {γF.Fk } and Rd = R { Xk / γM }
(= “at the source”, MFA)
or Ed = γE.E { Fk } and Rd = R { Xk } / γR
(RFA)
Design values of geotechnical
parameters
Brussels, 18-20 February 2008 – Dissemination of information workshop 15
EUROCODES
Background and Applications
Ultimate limit statesUltimate limit states –– Eurocode 7Eurocode 7--11
EQU : loss of equilibrium of the structure
STR : internal failure or excessive deformation
of the structure or structural elements
GEO : failure or excessive deformation of the
ground
UPL : loss of equilibrium due to uplift by water
pressure (buoyancy) or other vertical actions
HYD : hydraulic heave, internal erosion and
piping caused by hydraulic gradients
Brussels, 18-20 February 2008 – Dissemination of information workshop 16
EUROCODES
Background and Applications
J.A CalgaroJ.A CalgaroEEdd<< RRdd
EN1990EN1990 -- Ultimate limit states EQU and STR/GEOUltimate limit states EQU and STR/GEO
Brussels, 18-20 February 2008 – Dissemination of information workshop 17
EUROCODES
Background and Applications
1,50
0
1,35
1,00
Set A1
γ Q
γ Q
γ G
γ G
Symbol
Variable
Unfavourable
Favourable
Permanent
Unfavourable
Favourable
Action (γ F)
1,30
0
1,00
1,00
Set A2
1,251,00γc’Effective cohesion
1,00
1,00
1,00
1,00
Set M1
1,25γϕ’
Angle of shearing
resistance
1,40γcu
Undrained shear
strength
γγ
γqu
Symbol
1,00Weight density
1,40Unconfined strength
Set M2Soil parameter (γ M )
A2 “+” M2 “+” R1
Or A2 “+” M1 or M2“+” R4
A1 “+” M1 “+” R1
&
1
A1 “+” M1 “+” R22
A1 or A2 “+” M2 “+” R3
Combinations
3
Approach
1,1
1,4
Set R2
1,001,00γRh
Sliding
1,00
Set R1
1,00γRv
Bearing Portance
Symbol Set R3Resistance (γ R )
γR for Spread
foundations
STR/GEO : persistent and transient situations
Brussels, 18-20 February 2008 – Dissemination of information workshop 18
EUROCODES
Background and Applications
STR/GEOSTR/GEO :: accidental situationsaccidental situations
Actions : all values ofActions : all values of γγFF (and(and γγMM) = 1.0) = 1.0
Resistances :Resistances :
all values ofall values of γγRR (and(and γγMM) depend) depend
on the particular accidenton the particular accident
Seismic situations:Seismic situations: see Eurocode 8-5
10. Brussels, 18-20 February 2008 – Dissemination of information workshop 19
EUROCODES
Background and Applications
Ultimate limit states (UPL)
P
T
Anchorage
W
T
Anchored
structure
W
u
Former ground surface
Sand
Clay
Gravel
Clay
Sand
Clay
Gravel
b
bottom of
an
excavation
Sand
Sand
Sand
Injected sand
u
Water
tight
surface
slab below
water level
W TT
u
Water
tight
surface
b
buried
hollow
structure
u
σv
W atertight surface lightweight
embankment
during flood
Gdst;d + Qdst;d ≤ Gstb;d + RdExamples of situations where uplift
might be critical
Brussels, 18-20 February 2008 – Dissemination of information workshop 20
EUROCODES
Background and Applications Ultimate limit states (HYD)
Sand
WaterHeave due
to
seepage
of water
Permeable
subsoil
piezometric level in
the permeable
subsoil
low
permeability
soil
Piping
udst;d ≤ σstb;d
Δudst;d ≤ σ´stb;d
Example of situation where heave or piping might be critical
Brussels, 18-20 February 2008 – Dissemination of information workshop 21
EUROCODES
Background and Applications
Ultimate limit states of static equilibriumUltimate limit states of static equilibrium (EQU)(EQU) ::
EEd,dstd,dst ≤≤ EEd,stbd,stb
Ultimate limit states of resistanceUltimate limit states of resistance (STR/GEO)(STR/GEO) ::
EEdd ≤≤ RRdd
Ultimate limit state of upliftUltimate limit state of uplift (UPL)(UPL) ::
GGdst;ddst;d + Q+ Qdst;ddst;d ≤≤ GGstb;dstb;d + R+ Rdd
Ultimate limit state of hydraulic failureUltimate limit state of hydraulic failure (HYD)(HYD) ::
uudst;ddst;d ≤≤ σσstb;dstb;d or Sor Sdst;ddst;d ≤≤ GG´´stb;dstb;d
Verifications of ULSVerifications of ULS
Brussels, 18-20 February 2008 – Dissemination of information workshop 22
EUROCODES
Background and Applications
EN1990EN1990 -- Serviceability limit states SLSServiceability limit states SLS
Verifications :Verifications :
CCdd == limiting design value of the relevantlimiting design value of the relevant
serviceability criterionserviceability criterion
EEdd == design value of the effects of actionsdesign value of the effects of actions
specified in the serviceability criterion, determinedspecified in the serviceability criterion, determined
on the basis of the relevant combinationon the basis of the relevant combination
allall γγFF andand γγMM = 1.0= 1.0
EEdd ≤≤ CCdd
Brussels, 18-20 February 2008 – Dissemination of information workshop 23
EUROCODES
Background and Applications
settlement s, differential
settlement δs, rotation
θ and angular strain α
relative deflection Δ and
deflection ratio Δ/L
ω and relative rotation
(angular distortion) β
(after Burland and Wroth,
1975)
smax
δsmax
Movements and deformations of structuresMovements and deformations of structures
Brussels, 18-20 February 2008 – Dissemination of information workshop 24
EUROCODES
Background and Applications Conclusions
- a tool to help European geotechnical
engineers speak the same language
- a necessary tool for the dialogue between
geotechnical engineers and structural
engineers
Eurocode 7Eurocode 7 helps promoting research
- it stimulates questions on present geotechnical
practice from ground investigation to design
models
Eurocode 7 :Eurocode 7 :
11. Brussels, 18-20 February 2008 – Dissemination of information workshop 25
EUROCODES
Background and Applications
and to really conclude :
It should be considered that knowledge of the
ground conditions depends on the extent and
quality of the geotechnical investigations. Such
knowledge and the control of workmanship are
usually more significant to fulfilling the
fundamental requirements than is precision in
the calculation models and partial factors.
Brussels, 18-20 February 2008 – Dissemination of information workshop 26
EUROCODES
Background and Applications
Thank you for your attention !
12.
13. SECTION 2: BASIS OF GEOTECHNICAL
DESIGN
B. Schuppener
Bundesanstalt für Wasserbau
14.
15. Brussels, 18-20 February 2008 – Dissemination of information workshop 1
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
EN 1997
Eurocode: Geotechnical design
Section 2: Basis of
geotechnical design
Dr.-Ing. Bernd Schuppener,
Federal Waterways Engineering and Research Institute,
Karlsruhe, Germany
Brussels, 18-20 February 2008 – Dissemination of information workshop 2
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.1 Design requirements
2.2 Design situations
2.3 Durability
2.4 Geotechnical design by calculation
2.5 Design by prescriptive methods
2.6 Load tests
2.7 The Observational Method
2.8 The Geotechnical Design Report
Annex A + B
2 Basis of geotechnical design
Brussels, 18-20 February 2008 – Dissemination of information workshop 3
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P For each geotechnical design situation it shall be
verified that no relevant limit state, as defined in EN
1990:2002, is exceeded.
2.1 Design requirements
limit states
(4) Limit states should be verified by one or a combination
of the following:
• use of calculations as described in 2.4;
• adoption of prescriptive measures, as described in 2.5;
• experimental models and load tests, as described in 2.6;
• an observational method, as described in 2.7.
Brussels, 18-20 February 2008 – Dissemination of information workshop 4
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(8)P In order to establish minimum requirements
• for the extent and content of geotechnical investigations,
• calculations and
• construction control checks,
the complexity of each geotechnical design shall be
identified together with the associated risks.
(10) To establish geotechnical design requirements,
three Geotechnical Categories, 1, 2 and 3, may be
introduced.
2.1 Design requirements
Geotechnical Categories
Brussels, 18-20 February 2008 – Dissemination of information workshop 5
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(14) Geotechnical Category 1 should only include
small and relatively simple structures:
• for which it is possible to ensure that the fundamental
requirements will be satisfied on the basis of
experience and qualitative geotechnical investigations;
• with negligible risk.
2.1 Design requirements
Geotechnical Categories
(9) For structures and earthworks of low geotechnical
complexity and risk, such as defined above, simplified
design procedures may be applied.
Brussels, 18-20 February 2008 – Dissemination of information workshop 6
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(17) Geotechnical Category 2 should include
conventional types of structure and foundation with no
exceptional risk or difficult soil or loading conditions.
(18) Designs for structures in Geotechnical Category 2
should normally include quantitative geotechnical data
and analysis to ensure that the fundamental
requirements are satisfied.
(19) Routine procedures for field and laboratory testing
and for design and execution may be used for
Geotechnical Category 2 designs.
2.1 Design requirements
Geotechnical Categories
16. Brussels, 18-20 February 2008 – Dissemination of information workshop 7
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(20) Geotechnical Category 3 should include structures
or parts of structures, which fall outside the limits of
Geotechnical Categories 1 and 2.
(21) Geotechnical Category 3 should normally include
alternative provisions and rules to those in this standard.
NOTE Geotechnical Category 3 includes the following examples:
• very large or unusual structures;
• structures involving abnormal risks, or unusual or exceptionally
difficult ground or loading conditions;
• structures in highly seismic areas;
• structures in areas of probable site instability or persistent ground
movements that require separate investigation or special measures.
2.1 Design requirements
Geotechnical Categories
Brussels, 18-20 February 2008 – Dissemination of information workshop 8
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P Both short-term and long-term design situations
shall be considered.
2.2 Design Situations (EN 1997-1)
Brussels, 18-20 February 2008 – Dissemination of information workshop 9
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P At the geotechnical design stage, the
significance of environmental conditions shall be
assessed in relation to durability and to enable
provisions to be made for the protection or
adequate resistance of the materials.
2.3 Durability
Brussels, 18-20 February 2008 – Dissemination of information workshop 10
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P The selection of characteristic values for geotech-
nical parameters shall be based on results and derived
values from laboratory and field tests, complemented by
well-established experience.
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
(2)P The characteristic value of a geotechnical parameter
shall be selected as a cautious estimate of the value
affecting the occurrence of the limit state.
Brussels, 18-20 February 2008 – Dissemination of information workshop 11
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
4)P The selection of characteristic values for geotechnical
parameters shall take account of the following:
• ...
• the type and number of samples;
• the extent of the zone of ground governing the
behaviour of the geotechnical structure at the limit state
being considered;
• the ability of the geotechnical structure to transfer loads
from weak to strong zones in the ground. …..
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
Brussels, 18-20 February 2008 – Dissemination of information workshop 12
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(10) If statistical methods are employed in the selection of
characteristic values for ground properties, such methods
should differentiate between local and regional sampling
and should allow the use of a priori knowledge of
comparable ground properties.
(11) If statistical methods are used, the characteristic
value should be derived such that the calculated
probability of a worse value governing the occurrence of
the limit state under consideration is not greater than 5%.
NOTE In this respect, a cautious estimate of the mean value is a
selection of the mean value of the limited set of geotechnical
parameter values, with a confidence level of 95%; where local failure
is concerned, a cautious estimate of the low value is a 5% fractile.
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
17. Brussels, 18-20 February 2008 – Dissemination of information workshop 13
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Slope failure in a cut
cu = 68 MN/m²
cu = 73 MN/m²
cu = 65 MN/m²
cu = 71 MN/m²
cu = 60 MN/m²
cu = 55 MN/m²
cu = 50 MN/m²
cu = 62 MN/m²
cu = 76 MN/m²
cu = 64 MN/m²
cu = 75 MN/m²
Selection of characteristic values:
Brussels, 18-20 February 2008 – Dissemination of information workshop 14
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
cu = 68 MN/m²
cu = 73 MN/m²
cu = 65 MN/m²
cu = 71 MN/m²
cu = 60 MN/m²
cu = 55 MN/m²
cu = 50 MN/m²
cu = 62 MN/m²
cu = 76 MN/m²
cu = 64 MN/m²
cu = 75 MN/m²
Selection of characteristic values:
Brussels, 18-20 February 2008 – Dissemination of information workshop 15
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Determination of the characteristic value Xk by statistical
methods:
Xk = Xmean (1 - kn Vx)
where
Xmean arithmetical mean value of the parameter values;
Vx the coefficient of variation
kn statistical coefficient which depends on the number
n of test results, the level of confidence and a priori
knowledge about the coefficient of variation (case
”Vx unknown” or ”Vx known”).
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
Brussels, 18-20 February 2008 – Dissemination of information workshop 16
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Xk(local)
Number n
of test
results
*
*
*
*
*
*
*
*
*
*
*
*
Value of
parameter
Normal distribution
through tests results
Mean of test results Xmean
Xmean kn,mean Vx
Xmean
Xk(mean)
sxsx
Xmean kn,fractile Vx
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
Brussels, 18-20 February 2008 – Dissemination of information workshop 17
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
Determination of characteristic values proposed
by Schneider (1999):
Xk = Xmean - 0.5 sx
Brussels, 18-20 February 2008 – Dissemination of information workshop 18
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Example: results of triaxial tests used for the selection of the
characteristic values using statistical methods (Vx unknown)
Borehole / test
Statistical result
c’
[kPa]
’
[°]
tan ’
[-]
BH 1/1 3 31 0,601
BH 1/2 4 30 0,577
BH 2/1 1 35 0,700
BH 2/2 7 28 0,532
Mean value c´mean = 3.75 (tan ´)mean = 0.603
Standard deviation sc = 2.50 s = 0.071
Coefficient of variation Vc = 0.667 Vtan = 0.118
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
18. Brussels, 18-20 February 2008 – Dissemination of information workshop 19
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Table: summary of the statistical evaluation of the example
Characteristic values of
shear parameter
Basis and method
of statistical evaluation
´k [°] c´k [kPa]
’ and c’ of 4 tests
for the case “Vx unknown”
27.5 0.8
’ and c’ of 4 tests
for the case “Vx known”
29.0 2.5
Schneider (1999) 29.5 2.5
2.4 Geotechnical design by calculation
2.4.5.2 Characteristic values of geotechnical parameters
Brussels, 18-20 February 2008 – Dissemination of information workshop 20
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P The definition of actions shall be taken from EN
1990:2002. The values of actions shall be taken from EN
1991, where relevant.
Section 1 of EN 1997-1:
1.5.2.1 Geotechnical action
Action transmitted to the structure by the ground, fill
standing water or groundwater.
2.4 Geotechnical design by calculation
2.4.2 Actions
Brussels, 18-20 February 2008 – Dissemination of information workshop 21
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
NOTE (to (9)P) Unfavourable (or destabilising) and
favourable (or stabilising) permanent actions may in some
situations be considered as coming from a single source. If
they are considered so, a single partial factor may be
applied to the sum of these actions or to the sum of their
effects.
2.4 Geotechnical design by calculation
2.4.2 Actions
Brussels, 18-20 February 2008 – Dissemination of information workshop 22
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4 Geotechnical design by calculation
2.4.2 Actions
Wtop
Wbottom
Wd,dst = (Wbottom - Wtop) dst
Wd = Wbottom dst - Wtop stb
Brussels, 18-20 February 2008 – Dissemination of information workshop 23
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
• characteristic values
• geotechnical parameter
• actions
• design values
• geotechnical ultimate limit states
• design approaches DA1, DA2 and DA 3
• serviceability limit states
2.4 Geotechnical design by calculation
Brussels, 18-20 February 2008 – Dissemination of information workshop 24
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.6.1 Design values of actions
(2)P The design value of an action (Fd) shall either be
assessed directly or shall be derived from representative
values Frep using the following equation:
Fd = F Frep (2.1a)
with
Frep = Fk (2.1b)
where F is the partial factor on geotechnical actions or
effects of geotechnical actions and is a combination factor.
(3)P Appropriate values of shall be taken from EN
1990:2002.
19. Brussels, 18-20 February 2008 – Dissemination of information workshop 25
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.6.1 Design values of actions
(2)P The design value of an action (Fd) shall either be
assessed directly or shall be derived from representative
values Frep using the following equation:
Fd = F Frep (2.1a)
with
Frep = Fk (2.1b)
where F is the partial factor on geotechnical actions or
effects of geotechnical actions and is a combination factor.
(4)P The partial factor F for persistent and transient
situations defined in Annex A shall be used in equation
(2.1a).
Brussels, 18-20 February 2008 – Dissemination of information workshop 26
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.6.1 Design values of actions
00Favourable
1,31,5QUnfavourableVariable
1,01,0Favourable
1,01,35GUnfavourablePermanent
A2A1
Set
SymbolAction
Table A.3: Partial factors on actions ( F) or the effects of actions ( E)
NOTE The values to be ascribed to G and Q for use in a
country may be found in its National annex to EN 1990.
The recommended values for buildings in EN 1990:2002
for the two sets A1 and A2 are given in Table A.3.
Brussels, 18-20 February 2008 – Dissemination of information workshop 27
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.6.2 Design values of geotechnical
parameters
(1)P Design values of geotechnical parameters (Xd) shall
either be derived from characteristic values using the
following equation:
Xd = Xk / M (2.2)
or shall be assessed directly.
(2)P The partial factor M for persistent and transient
situations defined in Annex A shall be used in equation
(2.2).
Brussels, 18-20 February 2008 – Dissemination of information workshop 28
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.6.2 Design values of geotechnical
parameters
Table A.4 - Partial factors for soil parameters ( M)
Set
Soil parameter Symbol M1 M2
Shearing resistance 1
1,0 1,25
Effective cohesion c 1,0 1,25
Undrained strength cu 1,0 1,4
Unconfined strength qu 1,0 1,4
Unit weight density 1,0 1,0
Brussels, 18-20 February 2008 – Dissemination of information workshop 29
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P Where relevant, it shall be verified that the following limit
states are not exceeded:
• …………..
• failure or excessive deformation of the ground, in which the
strength of soil or rock is significant in providing resistance
(GEO);
• loss of equilibrium of the structure or the ground due to
uplift by water pressure (buoyancy) or other vertical actions
(UPL);
• hydraulic heave, internal erosion and piping in the ground
caused by hydraulic gradients (HYD).
2.4.7 Ultimate limit states
2.4.7.1 General
Brussels, 18-20 February 2008 – Dissemination of information workshop 30
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(1)P When considering a limit state of rupture or excessive
deformation of a structural element or section of the
ground (STR and GEO), it shall be verified that:
Ed Rd (2.5)
Ed : the design value of the effects of all the actions;
Rd : the design value of the corresponding resistance
of the ground and/or structure.
2.4.7.3 Verification of
resistance for GEO and STR
20. Brussels, 18-20 February 2008 – Dissemination of information workshop 31
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Load and Resistance Factor Approach
Rd Ed
Rk( ´k, c´k) / R Ek( ´k, c´k) E
Rk: characteristic values of ground resistance
R: partial factor for the ground resistance
Ek: characteristic value of the effect of action
E: partial factor for the effect of action or the
action
´k,c´k: characteristic values of the shear parameter
Brussels, 18-20 February 2008 – Dissemination of information workshop 32
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Design values of shear parameter
´k, c´k characteristic value of shear parameter
´d, c´d design values of the shear parameter
partial factor for the angle of shearing
resistance
c partial factor for the cohesion intercept
tan ´d = (tan ´k) /
c´d = c´k / c
Brussels, 18-20 February 2008 – Dissemination of information workshop 33
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Material Factor Approach
Rd( ´d, c´d) Ed( ´d, c´d)
Rd: design value of the ground resistance
Ed design value of the effects of actions of the
ground
´d design value of the angle of shearing
resistance
c´d design value of the cohesion intercept
Brussels, 18-20 February 2008 – Dissemination of information workshop 34
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Gk
EQ
Qk
EG
qk
Rv = (V, H, M, ´, c´)
Example for the three
Design Approaches of EN 1997-1
Rv,d Vd
V, H, M
Brussels, 18-20 February 2008 – Dissemination of information workshop 35
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Action or effects of actionsDesign
Approach structure ground
Resistance
ground
1
2222 G = 1.35; G,inf = 1.00; Q = 1.50 R;e = R;v = 1.40
R;h = 1.10
332 G = 1.35; G,inf=1.00
Q = 1.50
= c = 1.25
2.4.7.3 Verification of resistance for GEO and STR
Brussels, 18-20 February 2008 – Dissemination of information workshop 36
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Action or effects of actionsDesign
Approach Structure Ground
Resistance
ground
Comb. 1 G = 1.35; G,inf = 1.00; Q = 1.50 = c = 1.0
1
Comb. 2 G = 1.00; Q = 1.30 = c = 1.25
2 G = 1.35; G,inf = 1.00; Q = 1.50 R;e = R;v = 1.40
R;h = 1.10
3 G = 1.35; G,inf=1.00
Q = 1.50
= c = 1.25
2.4.7.3 Verification of resistance for GEO and STR
Design Approach 1
21. Brussels, 18-20 February 2008 – Dissemination of information workshop 37
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.7.3 Verification of resistance for GEO and STR
Design Approach 1
Gd = G Gk = 1.35 Gk
Qd = Q Qk = 1.50 Qk
EG,d= G EG( ´d,c´d)=1.35 EG( ´k,c´k)
EQ,d = EQ( ´k, c´k, qd)
qd = Q qk = 1.50 qk
Rv,d = Rv(Vd, Hd, Md, ´d, c´d)
´ = c = 1.0
´d = ´k, c´d = c´k
´ = c = 1.0
´d = ´k, c´d = c´k
Combination 1
Gd = G Gk = 1.00 Gk
Qd = Q Qk = 1.30 Qk
EG,d = G EG( ´d, c´d) = 1.00 EG( ´d, c´d)
qd = Q qk = 1.30 qk
tan ´d = tan ´k/ ´ = tan ´k/1.25
c´d = c´k / c = c´k / 1.25
tan ´d = tan ´k/ ´ = tan ´k/1.25
c´d = c´k / c = c´k / 1.25
EQ,d = EQ( ´d, c´d, qd)
Rv,d = Rv (Vd, Hd, Md, ´d, c´d)
Combination 2
Rv,d Vd
Vd, Hd, Md
Vd, Hd, Md Vd, Hd, Md
Vd, Hd, Md
Brussels, 18-20 February 2008 – Dissemination of information workshop 38
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Action or effects of actionsDesign
Approach Structure Ground
Resistance
ground
Comb. 1 G = 1.35; G,inf = 1.00; Q = 1.50 = c = 1.0
1
Comb. 2 G = 1.0; Q = 1.30 = c = 1.25
2 G = 1.35; G,inf = 1.00; Q = 1.50 R;e = R;v = 1.40
R;h = 1.10
3 G = 1.35; G,inf=1.00
Q = 1.50
= c = 1.25
2.4.7.3 Verification of resistance for GEO and STR
Design Approach 2
Brussels, 18-20 February 2008 – Dissemination of information workshop 39
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Gd = G Gk = 1.35 Gk
Qd = Q Qk = 1.50 Qk
EG,d= G EG( ´d, c´d)=1.35 EG( ´k,c´k)
EQ,d = EQ( ´d, c´d, qd)
qd = Q qk = 1.50 qk
Rv,k = F(Md, Vd, Hd, ´d, c´d)
Rv,d Vd
´ = c = 1.00
´d = ´k, c´d = c´k
´ = c = 1.00
´d = ´k, c´d = c´k
2.4.7.3 Verification of resistance for GEO and STR
Design Approach 2
DA 2
Vd, Hd, Md
Vd, Hd, Md
Rv,d = Rv,k / Rv
= Rv,k /1.40
Gk
Qk
EQ,k = EQ( ´k, c´k, qk)
qk
Rv,k= (Mk, Vk, Hk, ´k, c´k)
Vd = G VG,k + Q VQ,k
Vd = 1.35 VG,k + 1.50 VQ,k
EG,k = EG( ´k, c´k)
= c = 1.0
´d = ´k, c´d = c´k
= c = 1.0
´d = ´k, c´d = c´k
DA 2*
Vk, Hk, Mk
Vk, Hk, Mk
Rv,d = Rv,k= / Rv = Rv,k/1.40
Brussels, 18-20 February 2008 – Dissemination of information workshop 40
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Action or effects of actionsDesign
Approach Structure Ground
Resistance
ground
Comb. 1 G = 1.35; G,inf = 1.00; Q = 1.50 = c = 1.0
1
Comb. 2 G = 1.0; Q = 1.30 = c = 1.25
2 G = 1.35; G,inf = 1.00; Q = 1.50 R;e = R;v = 1.40
R;h = 1.10
3 G = 1.35; G,inf=1.00
Q = 1.50
= c = 1.25
2.4.7.3 Verification of resistance for GEO and STR
Design Approach 3
Brussels, 18-20 February 2008 – Dissemination of information workshop 41
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Gd = G Gk = 1.35 Gk
Qd = Q Qk = 1.50 Qk
EQ,d = EQ( ´d, c´d, qd)
qd = Q qk = 1.30 qk
Rv,d = (Vd, Hd, ´d, c´d)
Vd = VG,d + VQ,d
EG,d = G EG( ´d,c´d) = 1.00 EG( ´d,c´d)
tan ´d = tan ´k/ ´ = tan ´k/1.25
c´d= c´k/ c = c´k / 1.25
tan ´d = tan ´k/ ´ = tan ´k/1.25
c´d= c´k/ c = c´k / 1.25
2.4.7.3 Verification of resistance for GEO and STR
Design Approach 3
Rv,d Vd
Brussels, 18-20 February 2008 – Dissemination of information workshop 42
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.4.8 Serviceability limit states
(1)P Verification for serviceability limit states in the ground or
in a structural section, element or connection, shall either
require that:
Ed Cd, (2.10)
or be done through the method given in 2.4.8 (4).
Ed: effects of the actions e.g. deformations, differential
settlements, vibrations etc.
Cd: limiting values
(2) Values of partial factors for serviceability limit states
should normally be taken equal to 1,0.
(5)P …… This limiting value shall be agreed during the
design of the supported structure
22. Brussels, 18-20 February 2008 – Dissemination of information workshop 43
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
(2) The maximum acceptable relative rotations for open
framed structures, infilled frames and load bearing or
continuous brick walls are unlikely to be the same but are
likely to range from about 1/2000 to about 1/300, to
prevent the occurrence of a serviceability limit state in the
structure. A maximum relative rotation of 1/500 is
acceptable for many structures. The relative rotation
likely to cause an ultimate limit state is about 1/150.
Annex H
(informative)
Limiting values of structural deformation and
foundation movement
Brussels, 18-20 February 2008 – Dissemination of information workshop 44
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.7 Observational method
(1) When prediction of geotechnical behaviour is difficult,
it can be appropriate to apply the approach known as "the
observational method", in which the design is reviewed
during construction.
(2)P The following requirements shall be met before
construction is started:
• acceptable limits of behaviour shall be established;
• the range of possible behaviour shall be assessed and
it shall be shown that there is an acceptable probability
that the actual behaviour will be within the acceptable
limits;
Brussels, 18-20 February 2008 – Dissemination of information workshop 45
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
• a plan of monitoring shall be devised, which will reveal
whether the actual behaviour lies within the acceptable
limits. The monitoring shall make this clear at a
sufficiently early stage, and with sufficiently short
intervals to allow contingency actions to be undertaken
successfully;
• the response time of the instruments and the procedures
for analysing the results shall be sufficiently rapid in
relation to the possible evolution of the system;
• a plan of contingency actions shall be devised, which
may be adopted if the monitoring reveals behaviour
outside acceptable limits.
2.7 Observational method
Brussels, 18-20 February 2008 – Dissemination of information workshop 46
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
2.8 Geotechnical Design Report
(1)P The assumptions, data, methods of calculation and
results of the verification of safety and serviceability
shall be recorded in the Geotechnical Design Report.
(2) The level of detail of the Geotechnical Design
Reports will vary greatly, depending on the type
of design. For simple designs, a single sheet may be
sufficient.
Brussels, 18-20 February 2008 – Dissemination of information workshop 47
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Information to be verified during construction.
Notes on maintenance and monitoring.
Concrete cas on un-softened glacial till with cu
60 kPa (pocket
penetrometer)
Calculations (or index calculations)
Characteristic load 60 kN/m.
Local experience plus Local Building Regulations (ref ……..) indicates
working bearing pressure of 100 kPa acceptable. Therefore adopt footings 0.6
m wide, minimum depth 0.5 m (Building Regs) but depth varies to reach cu
60
kPa – test on site.
Description of site surroundings:
Formerly agricultural land.
Gently sloping (4°)
Assumed stratigraphy used in design with properties:
Topsoil and very weathered glacial till up to 1 m thick, overlying
firm to stiff glacial till (cu
60 kPa on pocket penetrometer).
Codes and standards used (level of acceptable risk)
Eurocode 7
Local building regs
Section through structure showing actions:Report used:
Ground Investigation report (give ref. date)
Factual:
Bloggs Investigations Ltd report ABC/123 dated 21 Feb 95
Interpretation:
Ditto
Approved by: Date ……………
Checked by: Date ……………
Made by: Date ……………
Sheet no of ………Job No.Job Title
New start housing development
Structure Reference:
Strip foundations
2.8 Geotechnical Design Report
Brussels, 18-20 February 2008 – Dissemination of information workshop 48
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Summary
Section 2: Basis of geotechnical design:
• introduces Geotechnical Categories as options,
• describes geotechnical design situations
• defines characteristic values of
• geotechnical actions and
• the selection of ground parameter
• defines geotechnical ultimate limit states
• defines three Design Approaches as options and
• introduces the Observational Method as an
equivalent geotechnical design method
23. Brussels, 18-20 February 2008 – Dissemination of information workshop 49
EUROCODES
Background and Applications
EN 1997-1: Section 2: Basis of geotechnical design
Thank you
300. SECTION 7 PILE FOUNDATIONS
R. Frank
Ecole Nationale des Ponts et Chaussées
301.
302. Brussels, 18-20 February 2008 – Dissemination of information workshop 1
Background and Applications
EUROCODES
Design of pile foundations
following Eurocode 7-Section 7
Workshop “Eurocodes: background and applications”
Brussels, 18-20 Februray 2008
Roger FRANK, Professor
Ecole nationale des ponts et chaussées, Paris
Brussels, 18-20 February 2008 – Dissemination of information workshop 2
EUROCODES
Background and Applications Contents of Part 1 (EN 1997-1)
Section 1 General
Section 2 Basis of geotechnical
design
Section 3 Geotechnical data
Section 4 Supervision of construction,
monitoring and maintenance
Section 5 Fill, dewatering, ground
improvement and reinforcement
Section 6 Spread foundations
Section 7 Pile foundations
Section 8 Anchorages
Section 9 Retaining structures
Section 10 Hydraulic failure
Section 11 Site stability
Section 12 Embankments
Brussels, 18-20 February 2008 – Dissemination of information workshop 3
EUROCODES
Background and Applications
EN 1997-1:
E A sample semi-empirical method for bearing
resistance estimation
H Limiting foundation movements and structural
deformation
EN 1997-2:
D.7 Example of a method to determine the
compressive resistance of a single pile (CPT)
D.6 Example of a correlation between
compressive resistance of a single pile and
cone penetration resistance
E.3 Example of a method to calculate the
compressive resistance of a single pile (PMT)
Informative annexesInformative annexes
Brussels, 18-20 February 2008 – Dissemination of information workshop 4
EUROCODES
Background and Applications
Section 7 of EN 1997-1
•• Pile load testsPile load tests
•• Axially loaded pilesAxially loaded piles
-- ULS compressive or tensile resistanceULS compressive or tensile resistance
((‘‘bearing capacitybearing capacity’’))
-- Vertical displacements of pile foundations:Vertical displacements of pile foundations:
serviceability of the supported structureserviceability of the supported structure
•• Transversely loaded pilesTransversely loaded piles
•• Structural design of pilesStructural design of piles
Brussels, 18-20 February 2008 – Dissemination of information workshop 5
EUROCODES
Background and Applications Specificity of pile foundations
Need to take into account the actions due to ground
displacement :
- downdrag (negative skin friction)
- heave
- transverse loading
********************
* the design values of the strength and stiffness of the
moving ground should usually be upper values
* the ground displacement is treated as an action and an
interaction analysis is carried out,
or
* an upper bound of the force transmited by the ground is
introduced as the design action.
Brussels, 18-20 February 2008 – Dissemination of information workshop 6
EUROCODES
Background and Applications General
303. Brussels, 18-20 February 2008 – Dissemination of information workshop 7
EUROCODES
Background and Applications Pile load tests
Brussels, 18-20 February 2008 – Dissemination of information workshop 8
EUROCODES
Background and Applications
Brussels, 18-20 February 2008 – Dissemination of information workshop 9
EUROCODES
Background and Applications Axially loaded piles
Brussels, 18-20 February 2008 – Dissemination of information workshop 10
EUROCODES
Background and Applications
ULS Compressive or tensileULS Compressive or tensile
resistance of piles (bearingresistance of piles (bearing
capacity)capacity)
Brussels, 18-20 February 2008 – Dissemination of information workshop 11
EUROCODES
Background and Applications
ULS - From static load test results
7.6.2.2 Ultimate compressive resistance from static load tests
(8)P For structures, which do not exhibit capacity to transfer loads from weak piles to
strong piles, as a minimum, the following equation shall be satisfied:
( ) ( )
⎭
⎬
⎫
⎩
⎨
⎧
=
2
minmc;
1
meanmc;
kc; ;Min
ξξ
RR
R (7.2)
where ξ1 and ξ2 are correlation factors related to the number of piles tested and are
applied to the mean (Rc;m) mean and the lowest (Rc;m )min of Rc;m respectively.
NOTE The values of the correlation factors may be set by the National annex. The
recommended values are given in Table A.9.
Brussels, 18-20 February 2008 – Dissemination of information workshop 12
EUROCODES
Background and Applications
Characteristic resistance from
measured resistances
Table A.9 - Correlation factors ξ to derive characteristic values from static pile load tests
(n - number of tested piles)
ξ for n = 1 2 3 4 ≥ 5
ξ1 1,40 1,30 1,20 1,10 1,00
ξ2 1,40 1,20 1,05 1,00 1,00
304. Brussels, 18-20 February 2008 – Dissemination of information workshop 13
EUROCODES
Background and Applications
ULS – From ground test results :
‘Model pile’ method
7.6.2.3 Ultimate compressive resistance from ground test results
(5)P The characteristic values Rb;k and Rs;k shall either be determined by:
( )
( ) ( )
⎭
⎬
⎫
⎩
⎨
⎧
==
+
=+=
4
mincalc;
3
meancalc;calc;cals;calb;
ks;kb;kc; ;Min
ξξξξ
RRRRR
RRR (7.8)
where ξ3 and ξ4 are correlation factors that depend on the number of profiles of tests, n,
and are applied respectively: to the mean values (Rc;cal )mean = (Rb;cal + Rs;cal)mean =
(Rb;cal)mean + (Rs;cal)meanand to the lowest values (Rc;cal )min = (Rb;cal + Rs;cal)min,
NOTE The values of the correlation factors may be set by the National annex. The
recommended values are given in Table A.10.
Brussels, 18-20 February 2008 – Dissemination of information workshop 14
EUROCODES
Background and Applications
Table A.10 - Correlation factors ξ to derive characteristic values from ground test results
(n - the number of profiles of tests)
ξ for n = 1 2 3 4 5 7 10
ξ3 1,40 1,35 1,33 1,31 1,29 1,27 1,25
ξ4 1,40 1,27 1,23 1,20 1,15 1,12 1,08
Characteristic resistance from
calculated resistances
Brussels, 18-20 February 2008 – Dissemination of information workshop 15
EUROCODES
Background and Applications
ULS – From ground test results :
‘Alternative’ method
7.6.2.3 Ultimate compressive resistance from ground test results
(8) The characteristic values may be obtained by calculating:
Rb;k = Ab qb;k and ∑ ⋅=
i
iis qAR k;s;s;;k (7.9)
where qb;k and qs;i;k are characteristic values of base resistance and shaft friction in the
various strata, obtained from values of ground parameters.
NOTE If this alternative procedure is applied, the values of the partial factors γb and γs
recommended in Annex A may need to be corrected by a model factor larger than 1,0.
The value of the model factor may be set by the National annex.
Brussels, 18-20 February 2008 – Dissemination of information workshop 16
EUROCODES
Background and Applications
ULSULS -- Permanent and transientPermanent and transient
design situationsdesign situations -- Load factorsLoad factors
Brussels, 18-20 February 2008 – Dissemination of information workshop 17
EUROCODES
Background and Applications
ULSULS -- Permanent and transientPermanent and transient
design situationsdesign situations -- Resistance factorsResistance factors
Brussels, 18-20 February 2008 – Dissemination of information workshop 18
EUROCODES
Background and Applications
CharacteristicCharacteristic value :value :
RRkk = R /= R / ξξ where R =where R = γγRdRdRRcalcal or R = Ror R = Rmm (1)(1)
DesignDesign value :value :
RRdd = R= Rkk//γγtt oror RRdd = R= Rbkbk//γγbb + R+ Rsksk//γγss (2)(2)
AppliedApplied compression/tensioncompression/tension loadload ::
FFdd == γγFFFFkk (3)(3)
General conditionGeneral condition for ULS being :for ULS being :
FFdd ≤≤ RRdd (4)(4)
equations (1) to (4) lead to :equations (1) to (4) lead to :
FFkk ≤≤ R /R / γγFF..γγtt..ξξ = R / FS= R / FS (5)(5)
Design resistanceDesign resistance
305. Brussels, 18-20 February 2008 – Dissemination of information workshop 19
EUROCODES
Background and Applications
Piles in compression :Piles in compression :
Piles in tension :Piles in tension :
Piles in groupPiles in group
Brussels, 18-20 February 2008 – Dissemination of information workshop 20
EUROCODES
Background and Applications
Brussels, 18-20 February 2008 – Dissemination of information workshop 21
EUROCODES
Background and Applications
Vertical displacements of pile foundations
(serviceability of supported structure)
Vertical displacements under SLS conditions must
be assessed and checked against limiting value :
* Piles in compression
- downdrag must be taken into account
- settlement due to group action must be taken into
account
* Piles in tension
- check upward displacements in the same manner
Brussels, 18-20 February 2008 – Dissemination of information workshop 22
EUROCODES
Background and Applications
0
20
40
60
80
100
120
0 1 2 3 4 5 6 7
Pile Load (MN)
Settlement(mm)
Load Test 2
Pile Load Test Results
Load Settlement Settlement
(MN) Pile 1(mm) Pile 2 (mm)
0 0 0
0.5 2.1 1.2
1.0 3.6 2.1
1.5 5.0 2.9
2.0 6.2 4.1
3.0 10.0 7.0
4.0 18.0 14.0
5.0 40.0 26.0
5.6 63.0 40.0
6.0 100.0 56.0
6.4 80.0
Load Test 1
Example from pile load test results (Orr, 2005)
driven piles B = 0.40 m D = 15.0 m
allowable settlement is 10 mm
loads : Gloads : Gkk = 20,000 kN and Q= 20,000 kN and Qkk = 5,000 kN= 5,000 kN
Brussels, 18-20 February 2008 – Dissemination of information workshop 23
EUROCODES
Background and Applications Results
From Table, for n = 2 pile load tests : for n = 2 pile load
tests : ξ1 = 1.30 and ξ2 = 1.20
Rk = Min{5.3/1.30; 5.0/1.20} = Min{4.08; 4.17} = 4.08
DA 1DA 1--2 : F2 : Fdd = 26.5 MN and R= 26.5 MN and Rdd = 3.14 MN.= 3.14 MN.
9 piles are needed (neglecting group effects)9 piles are needed (neglecting group effects)
DA1DA1--1 : F1 : Fdd = 34.5 MN and R= 34.5 MN and Rdd = 4.08= 4.08
9 piles are also needed (neglecting group effects)9 piles are also needed (neglecting group effects)
DA 2 : FDA 2 : Fdd = 34.5 MN and R= 34.5 MN and Rdd = 3.71 MN= 3.71 MN
10 piles are needed (neglecting group effects).10 piles are needed (neglecting group effects).
Brussels, 18-20 February 2008 – Dissemination of information workshop 24
EUROCODES
Background and Applications
SLS – Serviceability check
* Gk + Qk = 25 MN
* load per pile : through analysis of the 2 load
curves for s 10 mm
* Same analysis as for ULS (ξ1 = 1.30 and
ξ2 = 1.20)
leads to Rk = Min{3.25/1.30; 3.0/1.20}
= 2.5 MN
* thus, 10 piles are needed (neglecting group
effects)
306. Brussels, 18-20 February 2008 – Dissemination of information workshop 25
EUROCODES
Background and Applications
Transversely loaded piles
Adequate safety against failure (ULS)
Ftr ≤ Rtr
One of the following failure mechanisms should
be considered :
- short piles : rotation or translation as a rigid
body
- for long slender piles : bending failure of the
pile with local yielding and displacement of
the soil near the top of the pile
Brussels, 18-20 February 2008 – Dissemination of information workshop 26
EUROCODES
Background and Applications
Transverse resistance Rtr :
* from head transverse displacement pile
load test
* from ground tests results and pile strength
parameters
The theory of beams with subgrade reaction
moduli can be used
Brussels, 18-20 February 2008 – Dissemination of information workshop 27
EUROCODES
Background and Applications
Transverse displacement
The following must be taken into
account:
- non linear soil : E(ε)
- flexural stiffness of the piles : EI
- fixity conditions (connections)
- group effect
- load reversals and cyclic loading
Brussels, 18-20 February 2008 – Dissemination of information workshop 28
EUROCODES
Background and Applications Conclusions
* importance of static pile load tests
* an innovative approach to pile capacity
taking account of number of load tests or
number of soil profiles
* need of assessing serviceability of structures
through displacement calculations
Designing pile foundations with Eurocode 7 :Designing pile foundations with Eurocode 7 :
Brussels, 18-20 February 2008 – Dissemination of information workshop 29
EUROCODES
Background and Applications
Thank you for your attention !