eurocodes - is-argebau2. contents of eurocode 7 - parts 1 & 2 3. some aspects of eurocode 7-1...

EUROCODESBackground 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

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

GEOTECHNICAL DESIGN PART 1 GENERAL RULES

R. Frank

Ecole Nationale des Ponts et Chaussées

Brussels, 18-20 February 2008 – Dissemination of information workshop 1


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



1. Introduction

2. Contents of Eurocode 7 - Parts 1 & 2

3. Some aspects of Eurocode 7-1Characteristic valuesULS Design ApproachesSLS –Serviceability limit states



EN 1990EN 1990

EN EN 19911991

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

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

Basis of StructuralBasis of Structuraldesigndesign

Actions onActions onstructuresstructures

««MaterialMaterial »»resistanceresistance

EN 1997EN 1997 EN 1998EN 1998 GeotechnicalGeotechnicaland and seismicseismic

designdesign

STRUCTURAL EUROCODESBrussels, 18-20 February 2008 – Dissemination of information workshop 4


EN 1997EN 1997--1 (2004)1 (2004) :: Part 1 Part 1 -- General rulesGeneral rules

EN 1997EN 1997--2 (2007)2 (2007) :: Part 2 Part 2 -- Ground investigation Ground investigation and testingand testing

Eurocode 7 – Geotechnical design



2. Contents of Eurocode 7 –Parts 1 & 2


EUROCODESBackground 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

Contents of Part 1 (cntd)Brussels, 18-20 February 2008 – Dissemination of information workshop 8

EUROCODESBackground 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 × iγR /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



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



Section 1 GeneralSection 2 Planning and reporting

of ground investigationsSection 3 Drilling, sampling and

gw measurementsSection 4 Field tests in soils and

rocksSection 5 Laboratory tests on soils

and rocksSection 6 Ground investigation

report> Also a number of Informative annexesInformative annexes



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



Type of testF= 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 projectEN 1997 -1

EN 1997 -2

C1 C2

Geotechnical properties



Characteristic valueof 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%.



Design value of a parameter : Xd = Xk / γM

Design values of actions and resistancesfulfilling 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



Ultimate limit states Ultimate limit states –– Eurocode 7Eurocode 7--11

EQU : loss of equilibrium of the structureSTR : internal failure or excessive deformation

of the structure or structural elementsGEO : failure or excessive deformation of the

groundUPL : loss of equilibrium due to uplift by water

pressure (buoyancy) or other vertical actionsHYD : hydraulic heave, internal erosion and

piping caused by hydraulic gradients



J.A CalgaroJ.A CalgaroEEdd< < RRdd

EN1990 EN1990 -- Ultimate limit states EQU and STR/GEOUltimate limit states EQU and STR/GEO



1,500

1,351,00

Set A1

γ Qγ Q

γ Gγ G

Symbol

VariableUnfavourableFavourable

PermanentUnfavourableFavourable

Action (γ F)

1,300

1,001,00

Set A2

1,251,00γc’Effective cohesion

1,001,00

1,00

1,00

Set M1

1,25γϕ’Angle of shearing

resistance

1,40γcuUndrained shear

strength

γγ

γqu

Symbol

1,00Weight density1,40Unconfined strength

Set M2Soil parameter (γ M )

A2 “+” M2 “+” R1Or A2 “+” M1 or M2“+” R4

A1 “+” M1 “+” R1&1

A1 “+” M1 “+” R22A1 or A2 “+” M2 “+” R3

Combinations

3

Approach

1,11,4

Set R2

1,001,00γRhSliding1,00

Set R11,00γRvBearing Portance

Symbol Set R3Resistance (γ R )γR for Spread

foundations

STR/GEO : persistent and transient situationsBrussels, 18-20 February 2008 – Dissemination of information workshop 18


STR/GEOSTR/GEO :: accidental situationsaccidental 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) depend ) depend

on the particular accident on the particular accident

Seismic situations:Seismic situations: see Eurocode 8-5


EUROCODESBackground and Applications Ultimate limit states (UPL)

P

T

Anchorage

WT

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 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


EUROCODESBackground 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



Ultimate limit states of static equilibrium Ultimate limit states of static equilibrium (EQU)(EQU) ::EEd,dstd,dst ≤≤ EEd,stbd,stb

Ultimate limit states of resistance Ultimate limit states of resistance (STR/GEO)(STR/GEO) ::EEdd ≤≤ RRdd

Ultimate limit state of uplift Ultimate limit state of uplift (UPL)(UPL) ::GGdst;ddst;d + Q+ Qdst;ddst;d ≤≤ GGstb;dstb;d + R+ Rdd

Ultimate limit state of hydraulic failure Ultimate limit state of hydraulic failure (HYD)(HYD) ::uudst;ddst;d ≤≤ σσstb;d stb;d or Sor Sdst;ddst;d ≤≤ GG´́stb;dstb;d

Verifications of ULSVerifications of ULSBrussels, 18-20 February 2008 – Dissemination of information workshop 22


EN1990 EN1990 -- Serviceability limit states SLSServiceability limit states SLS

Verifications :Verifications :

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



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

δ s

max

Movements and deformations of structuresMovements and deformations of structuresBrussels, 18-20 February 2008 – Dissemination of information workshop 24

EUROCODESBackground 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 :



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.



Thank you for your attention !

SECTION 2: BASIS OF GEOTECHNICAL DESIGN

B. Schuppener

Bundesanstalt für Wasserbau



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




2.1 Design requirements 2.2 Design situations2.3 Durability2.4 Geotechnical design by calculation2.5 Design by prescriptive methods 2.6 Load tests 2.7 The Observational Method2.8 The Geotechnical Design Report

Annex A + B

2 Basis of geotechnical design




(1)P For each geotechnical design situation it shall beverified that no relevant limit state, as defined in EN 1990:2002, is exceeded.

2.1 Design requirementslimit 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.




(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 beidentified together with the associated risks.

(10) To establish geotechnical design requirements,three Geotechnical Categories, 1, 2 and 3, may beintroduced.

2.1 Design requirementsGeotechnical Categories




(14) Geotechnical Category 1 should only includesmall and relatively simple structures:• for which it is possible to ensure that the fundamental

requirements will be satisfied on the basis ofexperience and qualitative geotechnical investigations;

• with negligible risk.


(9) For structures and earthworks of low geotechnicalcomplexity and risk, such as defined above, simplifieddesign procedures may be applied.




(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.





(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.





(1)P Both short-term and long-term design situationsshall be considered.

2.2 Design Situations (EN 1997-1)




(1)P At the geotechnical design stage, thesignificance of environmental conditions shall beassessed in relation to durability and to enableprovisions to be made for the protection oradequate resistance of the materials.

2.3 Durability




(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 calculation2.4.5.2 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.




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. …..





(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 aselection 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.





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:




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:




Determination of the characteristic value Xk by statisticalmethods:

Xk = Xmean (1 - kn Vx)

whereXmean arithmetical mean value of the parameter values;Vx the coefficient of variationkn 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”).





Xk(local)

Number n of test results

*

**

*

* *

*

*

**

*

*

Value of parameter

Normal distribution through tests results

Mean of test results Xmean

Xmean kn,mean Vx

XmeanXk(mean)

sxsx

Xmean kn,fractile Vx






Determination of characteristic values proposedby Schneider (1999):

Xk = Xmean - 0.5 sx




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





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





(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 actionAction transmitted to the structure by the ground, fill standing water or groundwater.

2.4 Geotechnical design by calculation2.4.2 Actions




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.






Wtop

Wbottom

Wd,dst = (Wbottom - Wtop) dst

Wd = Wbottom dst - Wtop stb




• 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




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.




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).




2.4.6.1 Design values of actions

00Favourable

1,31,5QUnfavourableVariable

1,01,0Favourable

1,01,35GUnfavourablePermanent

A2A1

SetSymbolAction

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.




2.4.6.2 Design values of geotechnicalparameters

(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).




2.4.6.2 Design values of geotechnicalparameters

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




(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 states2.4.7.1 General




(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




Load and Resistance Factor ApproachRd Ed

Rk( ´k, c´k) / R Ek( ´k, c´k) E

Rk: characteristic values of ground resistanceR: partial factor for the ground resistance

Ek: characteristic value of the effect of actionE: partial factor for the effect of action or the

action´k,c´k: characteristic values of the shear parameter




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




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

resistancec´d design value of the cohesion intercept




Gk

EQ

Qk

EG

qk

Rv = (V, H, M, ´, c´)

Example for the three Design Approaches of EN 1997-1

Rv,d VdV, H, M




Action or effects of actions Design Approach structure ground

Resistanceground

1

2222 G = 1.35; G,inf = 1.00; Q = 1.50 R;e = R;v = 1.40R;h = 1.10

332 G = 1.35; G,inf=1.00Q = 1.50

= c = 1.25

2.4.7.3 Verification of resistance for GEO and STR




Action or effects of actionsDesignApproach Structure Ground

Resistanceground

Comb. 1 G = 1.35; G,inf = 1.00; Q = 1.50 = c = 1.01

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=1.00Q = 1.50

= c = 1.25

2.4.7.3 Verification of resistance for GEO and STRDesign 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/1.25c´d = c´k / c = c´k / 1.25

tan ´d = tan ´k/ ´ = tan ´k/1.25c´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, MdVd, Hd, Md Vd, Hd, MdVd, Hd, Md





Resistanceground

Comb. 1 G = 1.35; G,inf = 1.00; Q = 1.50 = c = 1.01

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=1.00Q = 1.50

= c = 1.25





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


DA 2

Vd, Hd, MdVd, 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,kVd = 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, MkVk, Hk, Mk

Rv,d = Rv,k= / Rv = Rv,k/1.40





Resistanceground

Comb. 1 G = 1.35; G,inf = 1.00; Q = 1.50 = c = 1.01

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=1.00Q = 1.50

= c = 1.25





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/1.25c´d= c´k/ c = c´k / 1.25

tan ´d = tan ´k/ ´ = tan ´k/1.25c´d= c´k/ c = c´k / 1.25


Rv,d Vd




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




(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




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 probabilitythat the actual behaviour will be within the acceptablelimits;




• a plan of monitoring shall be devised, which will reveal whether the actual behaviour lies within the acceptablelimits. The monitoring shall make this clear at asufficiently early stage, and with sufficiently shortintervals to allow contingency actions to be undertakensuccessfully;

• the response time of the instruments and the procedures for analysing the results shall be sufficiently rapid inrelation to the possible evolution of the system;

• a plan of contingency actions shall be devised, which may be adopted if the monitoring reveals behaviouroutside acceptable limits.

2.7 Observational method




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 typeof design. For simple designs, a single sheet may be sufficient.




Information to be verified during construction.Notes on maintenance and monitoring.

Concrete cas on un-softened glacial till with cu 60 kPa (pocketpenetrometer)

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, overlyingfirm to stiff glacial till (cu 60 kPa on pocket penetrometer).

Codes and standards used (level of acceptable risk)Eurocode 7Local 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 95Interpretation:

Ditto

Approved by: Date ……………

Checked by: Date ……………

Made by: Date ……………

Sheet no of ………Job No.Job TitleNew start housing development

Structure Reference:Strip foundations

2.8 Geotechnical Design ReportBrussels, 18-20 February 2008 – Dissemination of information workshop 48



SummarySection 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




Thank you

SECTION 3 GEOTECHNICAL DATA AND 6 SPREAD FOUNDATIONS

T. Orr

Trinity College Dublin

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SECTION 7 PILE FOUNDATIONS

R. Frank Ecole Nationale des Ponts et Chaussées


Background and ApplicationsEUROCODES

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



Section 1 GeneralSection 2 Basis of geotechnical designSection 3 Geotechnical dataSection 4 Supervision of construction, monitoring and maintenanceSection 5 Fill, dewatering, ground improvement and reinforcementSection 6 Spread foundationsSection 7 Pile foundationsSection 8 Anchorages Section 9 Retaining structuresSection 10 Hydraulic failureSection 11 Site stabilitySection 12 Embankments



EN 1997-1: E A sample semi-empirical method for bearing

resistance estimationH 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 annexesBrussels, 18-20 February 2008 – Dissemination of information workshop 4

EUROCODESBackground and Applications Section 7 of EN 1997-1

•• Pile load testsPile load tests

•• Axially loaded pilesAxially loaded piles

-- ULS compressive or tensile resistance ULS 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


EUROCODESBackground 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.


EUROCODESBackground and Applications General


EUROCODESBackground and Applications Pile load tests




EUROCODESBackground and Applications Axially loaded piles



ULS Compressive or tensile ULS Compressive or tensile resistance of piles (bearing resistance of piles (bearing

capacity)capacity)



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

RRR (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.



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



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

RRRRRRRR (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.



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



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.



ULS ULS -- Permanent and transient Permanent and transient design situations design situations -- Load factorsLoad factors



ULS ULS -- Permanent and transient Permanent and transient design situations design situations -- Resistance factorsResistance factors



CharacteristicCharacteristic value :value :RRkk = R / = R / ξ ξ 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)

Applied Applied 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



Piles in compression :Piles in compression :

Piles in tension :Piles in tension :

Piles in groupPiles in groupBrussels, 18-20 February 2008 – Dissemination of information workshop 20




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



0

20

40

60

80

100

120

0 1 2 3 4 5 6 7

Pile Load (MN)

Settl

emen

t (m

m)

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


EUROCODESBackground 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= 4.089 piles are also needed (neglecting group effects)9 piles are also needed (neglecting group effects)

DA 2 : FDA 2 : Fd d = 34.5 MN and R= 34.5 MN and Rdd = 3.71 MN= 3.71 MN10 piles are needed (neglecting group effects).10 piles are needed (neglecting group effects).


EUROCODESBackground 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)


EUROCODESBackground 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



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


EUROCODESBackground and Applications Transverse displacement

The following must be taken intoaccount:- non linear soil : E(ε)- flexural stiffness of the piles : EI- fixity conditions (connections)- group effect- load reversals and cyclic loading


EUROCODESBackground 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 :



Thank you for your attention !

SECTION 8 ANCHORAGES SECTION 9 RETAINING STRUCTURES

B. Simpson

Arup

1


EUROCODESBackground and Applications EN1997-1: Anchorages and Retaining structures

EN 1997-1 Eurocode 7Section 8 – AnchoragesSection 9 – Retaining structures

Brian SimpsonArup Geotechnics

2 ©

EN 1997-1 Geotechnical design – General Rules BP106.9

BP111.5 BP112.6 BP124-T1.311 General2 Basis of geotechnical design3 Geotechnical data4 Supervision of construction, monitoring and maintenance5 Fill, dewatering, ground improvement and reinforcement6 Spread foundations7 Pile foundations8 Anchorages9 Retaining structures10 Hydraulic failure11 Overall stability12 Embankments

Appendices A to J

3 ©

8 AnchoragesBP124-F3.6

8.1 General

8.2 Limit states

8.3 Design situations and actions

8.4 Design and construction considerations

8.5 Ultimate limit state design

8.6 Serviceability limit state design

8.7 Suitability tests

8.8 Acceptance tests

8.9 Supervision and monitoring

4 ©

5 © 6 ©

2

7 © 8 ©

9 © 10 ©

8 Anchorages

• Section depends on EN1537 - Execution of special geotechnical work - Ground anchors

• Not fully compatible with EN1537. Further work on this is underway.

• BS8081 being retained for the time being.

11 ©

EN1537:1999

12 ©

EN1537:1999Execution of special geotechnical work - Ground anchors

3

13 ©

EN1537:1999 Execution of special geotechnical work - Ground anchors- provides details of test procedures (creep load etc)

14 ©

Partial factors in anchor design

15 ©

Partial factors in anchor designBrussels, 18-20 February 2008 – Dissemination of information workshop 16


EN 1997-1 Eurocode 7Section 8 – AnchoragesSection 9 – Retaining structures

Brian SimpsonArup Geotechnics



EN 1997-1 Eurocode 7

Section 9 – Retaining structures

Fundamentals – Design Approaches

Main points in the code text

Examples:Comparisons with previous (UK) practiceComparison between Design Approaches

Lessons from the Dublin Workshop









4

19 ©

Genting Highlands BP87.59 BP106.30 BP111.22 BP112.43 BP119.43 BP124-F3.9 BP130.33 BP145a.8 Genting Highlands BP87.60 BP106.31 BP111.23 BP112.44 BP119.44 BP124-F3.10 BP130.34 BP145a.9

21 ©

FOS > 1 for characteristic soil strengthsBP87.61 BP106.32 BP111.24 BP112.45

BP119.45 BP124-F3.11 BP130.35 BP145a.10

- but not big enough

22 ©

The slope and retaining wall are all part of the same

problem. BP87.62 BP106.33 BP111.25 BP112.46BP119.46 BP124-F3.12 BP130.36 BP145a.11

Structure and soil must be designed together - consistently.

23 ©

Approaches to ULS design –The merits of

Design Approach 1 in Eurocode 7Brian SimpsonArup Geotechnics BP145a.1

ISGSR2007 - First International Symposium on Geotechnical Safety and Risk Brussels, 18-20 February 2008 – Dissemination of information workshop 24








5

25 ©

EN 1997-1 Geotechnical design – General Rules BP106.9 BP111.5 BP112.6 BP124-T1.31

1 General2 Basis of geotechnical design3 Geotechnical data4 Supervision of construction, monitoring and maintenance5 Fill, dewatering, ground improvement and reinforcement6 Spread foundations7 Pile foundations8 Anchorages9 Retaining structures10 Hydraulic failure11 Overall stability12 Embankments

Appendices A to J

26 ©

9 Retaining structures

9.1 General9.2 Limit states9.3 Actions, geometrical data and design situations 9.4 Design and construction considerations 9.5 Determination of earth pressures 9.6 Water pressures 9.7 Ultimate limit state design 9.8 Serviceability limit state design

27 ©

9.2 Limit states

28 ©

9.2 Limit states

29 ©

9.3.2 Geometrical data

30 ©

9.3.2 Geometrical data

100%

10%

100%

10%

6

31 ©


32 ©


33 ©

9.4.2 Drainage systems

34 ©

9.5 Determination of earth pressures

35 ©

9.5 Determination of earth pressures

36 ©

9.5.3 Limiting values of earth pressure

Annex C also provides charts and formulae for the active and passive limit values of earth pressure.

7

37 ©

Annex C Sample procedures to determine limit values of earth pressures on vertical walls

• Based on Caquot and Kerisel (and Absi?).

• No values for adverse wall friction, which can lead to larger Ka and much smaller Kp.

38 ©

Wall friction

Adverse wall friction may be caused by loads on the wall from structures above, inclined ground anchors, etc.

39 ©

C.2 Numerical procedure for obtaining passive pressures

• Also provides Ka

• Programmable formulae (though not simple)

• Incorporated in some software (eg Oasys FREW, STAWAL)

• Precise source not known (to me), but same values as Lancellotta, R (2002) Analytical solution of passive earth pressure. Géotechnique 52, 8 617-619.

• Covers range of adverse wall friction.

• Slightly more conservative than Caquot & Kerisel when φ and δ/φ large – but more correct?

40 ©

Ka, Kp charts in Simpson & Driscoll

41 ©

Comparison with Caquot & Kerisel

Kp(C&K) / Kp(EC7) %

Ka(C&K) / Ka(EC7) %

42 ©

9.7 Ultimate limit state design

8

43 ©

9.7.2 Overall stability

44 ©

9.7.3 Foundation failure of gravity walls

45 ©

9.7.4 Rotational failure of embedded walls

46 ©

9.7.5 Vertical failure of embedded walls

47 ©

9.7.6 Structural design of retaining structures

48 ©

9.7.6 Structural design of retaining structures

9

49 ©

9.7.7 Failure by pull-out of anchorages

50 ©

9.8 Serviceability limit state design

51 ©

9.8.2 DisplacementsBrussels, 18-20 February 2008 – Dissemination of information workshop 52








53 ©

8m propped wall BP87.71 BP111.33 BP112.49 8m propped wall - data BP78.26 BP111.34BP112.50 BP119.50 BP124-F3.15

CASE: DA1

-1 DA1

-2 EC7 SLS

Unplanned overdig (m) 0.5 0.5 0 Dig level: Stage 1 -8.5 -8.5 -2.5 Stage 2 -8.0 Characteristic φ' ( ) 24 24 24 γ (or M) on tan φ' 1 1.25 1 Design φ' 24 19.6 24 δ'/φ' active 1 1 1 δ'/φ' passive 1 1 1 Ka 0.34 0.42 0.34Factor on Ka 1 1 1 Design Ka 0.34 0.42 0.34Kp 4.0 2.9 4.0 Factor on Kp 1 1 1 Design Kp Excd. side Retd. side

4.0 2.9 4.0 1.0

γQ 1 1.3 1

10

8m propped wall - length and BM BP78.28BP111.35 BP112.51 BP119.51 BP124-F3.16

CASE: DA1

-1 DA1

-2 EC7 SLS

Unplanned overdig (m) 0.5 0.5 0 Design φ' 24 19.6 24 Design Ka 0.34 0.42 0.34Design Kp Excd. side Retd. side

4.0 2.9 4.0 1.0

γQ 1 1.3 1 Computer program STW STW F Data file PROP11 PROP1 BCAP3AWall length (m) 15.1

* 17.9

* 17.8 **

Max bending moment (kNm/m)

1097 1519 -236 +682

Factor on bending moment 1.35 1 1 ULS design bending moment (kNm/m)

1481 1519 -236 +682

* Computed ** Assumed

Redistribution of earth pressure BP87.75 BP111.36 BP112.52BP119.52 BP124-F3.17

57 ©

Compare CIRIA 104 BP87.2 BP111.54 BP112.54 BP119.53 BP124-F3.18

58 ©

10kPa (13kPa)

0

-8m (-8.5m)

φ′ = 24° (19.6°)

59 ©

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