Harmonized European standards for construction in...

Organised with the support of the Egyptian Organization for Standardization and Quality

Harmonized European standards for construction in Egypt

Eurocode 7 ‘Geotechnical design’

Roger FrankProfessor, Ecole des Ponts ParisTech

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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

4. Liaisons. Associated standards

Outline

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EN 1990EN 1990

EN 1991EN 1991

EN 1992EN 1992 EN 1993EN 1993 EN 1994EN 1994

EN 1995EN 1995 EN 1996EN 1996 EN 1999EN 1999

Structural Structural safetysafety, ,

serviceabilityserviceability and and

durabilitydurability

Actions onActions on

structuresstructures

Design andDesign and

detailingdetailing

EN 1997EN 1997 EN 1998EN 1998GeotechnicalGeotechnical

and and seismicseismic

designdesign

STRUCTURAL EUROCODES

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•• EN 1997EN 1997--1 (2004) :1 (2004) : General General rulesrules

•• EN 1997EN 1997--2 (2007) :2 (2007) : GroundGround investigation investigation

and and testingtesting

Eurocode 7 – Geotechnical design

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2. Contents of Eurocode 7 –Parts 1 & 2

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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

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• 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

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Informative annexes

Annexes D & E : Bearing capacity of

foundations

R/A' = c' ×××× Nc ×××× bc ×××× sc ×××× ic +

q' ×××× Nq ×××× bq ×××× sq ×××× iq +

0,5 ×××× γγγγ' ×××× B '×××× Nγγγγ ×××× bγγγγ ×××× sγγγγ ×××× iγγγγ

R /A' = σσσσv0 + k ×××× p*le

Annex C Active earthpressure

Annexe C – Passive earthpressure

Annexe F : Settlement of foundations

s = p ×××× b ×××× f / Em

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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

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Clauses on :

CPT(U), PMT, FDT, SPT, DP, WST, FVT, DMT, PLT

� Objectives, specific requirements, evaluation of test results, use of test results and derived values

Annexes with examples on use of results and derivedvalues for geotechnical design

EN 1997- 2

Field tests in soils and rocks (Section 4)

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� preparation of soil specimens for testing� preparation of rock specimens for testing� tests for classification, identification and description of soils� chemical testing of soils and groundwater� strength index testing of soils� strength testing of soils� compressibility and deformation testing of soils� compaction testing of soils� permeability testing of soils� tests for classification of rocks� swelling testing of rock material� strength testing of rock material

EN 1997- 2

Lab. tests on soils and rocks (Section 5)

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Results of test standards (EN 1997-2 Annex A)

Test resultsField test

Soils: w ; ρ ; ρs ; grain size distribution curve ; wP , wL ; emax , emin , ID ; COM ; CCaCO3 ; CSO42-, CSO3

2- ; Ccl ; pH ; compressibility, consolidation, creep curves, Eoed, σ’p or Cs, Cc, σ’p, Cα ; cu (lab vane) ; cu (fall cone) ; qu ; cu (UU) ; σ-ε and u curves, σ−paths, Mohr circles ; c’, ϕ’ or cu, cu=f(σ’c), E’ or Eu ; σ-u curve, τ-σ diagram, c’, ϕ’, residualparameters ; ICBR ; k (direct lab, field or oedometer)

Rocks: w ; ρ and n ; swelling results ; σc, E and ν ; Is50 ; σ-u curve, Mohr diagram, c’, ϕ’, res par ; σT ; σ-ε curve, σ−paths, Mohr circles ; c’, ϕ’, E and ν

Laboratory tests

P0 , p1 , EDMT , IDMT , KDMT (DMT)Flta dilatometer test

puPlate loading test

continuous record of penetration depth or NbWeight sounding test (WST)

cfv , crv , torque-rotation curveField vane test (FVT)

EFDT, deformation curveFlexible dilatometer (FDT)

EM ,,pf , plM (MPM); expansion curve (all)Pressuremeters (PMT)

N , Er (SPT), soil descriptionSPT

N10 (DPL, DPM, DPH); N10 or N20 (DPSH)Dynamic probing

qc , fs , Rf (CPT) / qt , fs , u (CPTU)CPT/CPTU

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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 C2

Cautious selection

Geotechnical model and characteristicvalue of geotechnical properties

Design values of geotechnicalproperties

Application of partial factors

Information

from other

sources on

the site, the

soils and

rocks and

the projectEN 1997 -1

EN 1997 -2

Geotechnical properties

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3. Some aspects of Eurocode 7-1� CharacteristicCharacteristic values values

and design values and design values

�� ULS Design ULS Design ApproachesApproaches

�� SLS and SLS and deformationsdeformations of structures of structures

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Characteristic value of geotechnical parameters

P The characteristic valuecharacteristic valuecharacteristic valuecharacteristic valuecharacteristic valuecharacteristic valuecharacteristic 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%.

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Design value of a parameter : Xd = Xk / γM

Design values of actions and Design values of actions and resistancesresistances

fulfilling for STR/GEO ULS : Ed ≤ Rd

Ed = E {γF.Fk } and Rd = R { Xk / γM }

(= “at the source”)

or Ed = γE.E { Fk } and Rd = R { Xk } / γR

Design values of geotechnical parameters

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Ultimate limit states Ultimate limit states –– EurocodeEurocode 77--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

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EN1990 EN1990 -- UltimateUltimate limitlimit statesstates

EQU and STR/GEOEQU and STR/GEO

J.A CalgaroEEdd< < RRdd

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STR/GEO : ULS - persistent and transient situations

1,500

1,351,00

Set A1

γ Q

γ Q

γ G

γ G

Symbol

VariableUnfavourableFavourable

PermanentUnfavourableFavourable

Action (γ F)

1,300

1,001,00

Set A2

1,251,00γc’Effective cohesion

1,00

1,00

1,00

1,00

Set M1

1,25γϕ’Angle of shearing resistance

1,40γcuUndrained 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

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Appro-aches

1,1

1,4

Set R2

1,001,00γRhSliding

1,00

Set R1

1,00γRvBearing capacity

Symbol Set R3Resistance (γ R )

� γR for Spreadfoundations

EEdd< < RRdd

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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 T T

u

Water tight surface

b buriedhollowstructure

u

σ v

W atertight surface lightweight

embankment

during flood

Gdst;d + Qdst;d ≤≤≤≤ Gstb;d + RdExamples of situations where

uplift might be critical

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Ultimate limit states (HYD)

Sand

WaterHeave due to

seepage

of water

Permeablesubsoil

piezometric level in the permeable subsoil

lowpermeabilitysoil

Piping

udst;d ≤≤≤≤ σσσσstb;d

∆∆∆∆udst;d ≤≤≤≤ σσσσ´stb;d

Example of situation where heave or piping might be critical

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Accidental situations

Actions : all values of Actions : all values of γγFF (and (and γγMM) = 1.0) = 1.0

Resistances : Resistances :

all values of all values of γγRR (and (and γγMM) ) dependdepend

on the on the particularparticular accident accident

SeismicSeismic situations :situations : see Eurocode 8-5

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UltimateUltimate limitlimit states of states of staticstatic equilibriumequilibrium (EQU)(EQU) ::

EEd,dstd,dst ≤≤ EEd,stbd,stb

UltimateUltimate limitlimit states of states of resistanceresistance (STR/GEO)(STR/GEO) ::

EEdd ≤≤ RRdd

UltimateUltimate limitlimit state of state of upliftuplift (UPL)(UPL) ::

GGdst;ddst;d + + QQdst;ddst;d ≤≤ GGstb;dstb;d + R+ Rdd

UltimateUltimate limitlimit state of state of hydraulichydraulic failurefailure (HYD)(HYD) ::

uudst;ddst;d ≤≤ σσstb;dstb;d or or SSdst;ddst;d ≤≤ GG´́stb;dstb;d

VerificationsVerifications of ULSof ULS

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EN1990 EN1990 -- ServiceabilityServiceability limitlimit states states

SLSSLSVerificationsVerifications ::

CCdd = = limiting design value of the relevant limiting design value of the relevant

serviceability criterionserviceability criterion

EEdd = = design value of the effects of actions design value of the effects of actions

specified in the serviceability criterion, determined specified in the serviceability criterion, determined

on the basis of the relevant combinationon the basis of the relevant combination

all all γγFF and and γγMM = 1.0= 1.0

EEdd ≤≤ CCdd

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• settlement s, differential settlement δs, rotation θand angular strain α

• relative deflection ∆ and deflection ratio ∆/L

• ω and relative rotation (angular distortion) β

(after Burland and Wroth, 1975)

smax

δ δ δ δ s

max

MovementsMovements and and deformationsdeformations of structuresof structures

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Foundations of buildings (Eurocode 7, 1994)* Serviceability limit states (SLS) : βmax ≈ 1/500

* Ultimate limit states (ULS) : βmax ≈ 1/150• smax ≈ 50 mm δsmax ≈ 20 mm

Foundations of bridgesMoulton (1986) for 314 bridges in the US and Canada :

* βmax ≈ 1/250 (continuous deck bridges) and βmax ≈ 1/200 (simply supported spans)

* sHmax ≈ 40 mmIn France, in practice :

ULS : βmax ≈ 1/250SLS : βmax ≈ 1/1000 à 1/500

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4. Liaisons. Associated standards• EN 1990: Eurocode : Basis of structural design• EC 8 - 5 : Earthquake resistance design: foundations, retaining structures

and geotechnical aspects• TC 288 : Execution of geotechnical works • TC 341 : Geotechnical investigation and testing• ISO/TC 182 Geotechnics :

SC1 Soil and rock classificationSC3 Foundations, retaining structures & earthworks

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Published standards

EN 1536 : Bored piles (1999), 79 p

EN 1538 : Diaphragm walls (2000), 46 p

EN 1537 : Ground anchors (2000), 56 p

EN 12063 : Sheet piling (1999), 76 p

EN 12699 : Displacement piles (2001), 45 p

EN 12715 : Grouting (2000), 49 p

EN 12716 : Jet-grouting (2001), 36 p

EN 14199 : Micropiling (2005), 45 p

EN 14475 : Reinforcement of fills (2007), 49

EN 14490 : Soil Nailing (2010)

EN 14679 : Deep mixing (2005), 49 p

EN 14731 : Deep vibration (2006), 22 p

EN 15237 : Deep vertical drainage(2007), 52 p

Execution of geotechnical works – TC 288 (October 2010)

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Standards (4) – Short title (date of publication)

EN ISO 14688-1 : Identification of soils (2002-08)

EN ISO 14688-2 : Classification of soils (2004-07)

EN ISO 14689-1 : Identification of rock (2003-12)

EN ISO 22475-1 : Sampling - principles (2006-9)Technical specifications (12)TS 22475-2 : Sampling - qualification criteria (2006-9)TS 22475-3 : Sampling – conformity assessment (2007-12)

TS 17892-1 to 12 (2004-11) to be replaced by ENs:

Water content, Density of fine grained soils,

Density of solid particles, Particle size distribution,

Oedometer test, Fall cone test,

Unconfined compression test,

Unconsolidated triaxial test,

Consolidated triaxial test,

Direct shear test,

Permeability test,

Atterberg Limits

Investigation and laboratory testingPublished documents as of April 2010 (TC 341)

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Published standards (4) – Short title (date of publication)

EN ISO 22476-2 : Dynamic probing (2005-01)

EN ISO 22476-3 : Standard penetration test (2005-01)

Published technical specifications (2)TS 22476-10 : Weight sounding test (2005-05)

TS 22476-11 : Flat dilatometer test (2005-05)

DP

DMTWSTSPT

Field (in situ) testingPublished documents as of 1st April 2010 (TC 341)

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Conclusions

- a tool to help European geotechnical engineers speak the same language

- a necessary tool for the dialogue between geotechnical engineers and structural engineers

EurocodeEurocode 77 helps promoting research

- it stimulates questions on present geotechnical practice from ground investigation to design models

EurocodeEurocode 7 7 isis ::

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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.

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Thank you for your attention !

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Contact Us

www.bsigroup.comLinks:

[email protected]:

Roger FrankName of Speaker:

Professor Title:

Ecole des Ponts ParisTechOrganisation:

www.bsigroup.comLinks:

[email protected]:

Keith MoyesProject Team Leader:

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