Eric R Farrell C ll bl Trinity College, Dublin

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

FILL 1m

2H:1V side slopes γ = 19 kN/m3 ck′=0kPa; φk′=32.5o

Topsoil 3m

H?

Few dm of clay γ=18 kN/m3

PSEUDO-FIBROUS TO AMORPHOUS HOLOCENE PEAT

γγ′= 2 kN/m3

ck′=0kPa; φk′=32.5o

PLEISTOCENE SAND MEDIUM DENSE

γγ′= 11 kN/m3

ck′=0kPa; φk′=35o 2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Information supplied 2 No No. Borehole logs 5 No vane tests to DIN 4094:2002 (75mm dia.) Vanes at spacing of 40m to 50m on centerline.

Comment ¾No information on method of construction of boreholes ¾No

laboratory test data

¾No

desk study (previous experience)

¾Correlation

cuvane?

factors for

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Stratification

M Measured d cu values l (kP (kPa))

0.0

10.0

20.0

30.0

-1 2 -2 -3 4 -4 NN (m)

PSEUDO-FIBROUS PSEUDO FIBROUS TO AMORPHOUS PEAT

-5 6 -6

FVT1 FVT2 FVT3 FVT4 FVT5

-7 8 -8

SAND

-9

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

¾

DETERMINE THE HEIGHT OF EMBANKMENT FOR INITIAL STAGE

Design g assumptions p ¾ ¾ ¾ ¾ ¾

Topsoil not to be removed No hydraulic fill at the rear No serviceability requirements No accidental design situations No construction traffic to be considered.

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q2 How many structures of this kind have you previously designed?

Q3 Having completed your design to EC7, EC7 how confident are you that the design is sound?

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q4 Which calculation model did you use to determine the maximum height of the embankment? Annex D from EN1997-1 Alternative given in NA Alternative given in National Standard Terzaghi Meyerhof Brinch-Hansen Limiting equilibrium (Slip circle/method of slices) Limiting equilibrium (wedge mechanism) Finite element analysis Finite difference analysis Other (Specify) NO RESPONSES (LATER COMMENTS INDICATE SLIP CIRCLE AND BEARING CAPACITY MODELS)

Q5 If you used the slip circle method,, what variant of this method did you use?

Bishop with horizontal interslice forces Bishop with variable inclined interslice forces Spencer/Bishop with constantly inclined interslice forces Janbu with horizontal interslice forces Janbu with variably inclined interslice forces Janbu with constantly inclined interslice forces Morgenstern and Price Other (Specify) NO FORMAL RESPONSES (later responses, Bishop’s variable interslice forces and bearing capacity)

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q6 Which parameters did you use for the ULS design of the embankment?

Q7 What corrections did you use to derive soil parameter values (if used) for the USL verification? a) Annex-I from EN-1997-2 (no correction specifically for peat, which depends on size of vane, plot for clay sometimes used.).

2N No off th the 12N 12No submissions b i i used corrected shear strengths

FOR CLAY

b) DIN 1055-2

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q7a

Any other correlations?

NO RESPONSE

Q8 What assumptions did you make in choosing these correlations? a)) N None – would ld h have researched h d more if given more time b) None but also did not reduce g following 2 2.4.7.1(5). 4 7 1(5) Arguably might have used lower strength and lower factors c) Peat is NC (required to use the correction factors from Eurocode d) Ys=y’+10y=ys-1 kN/m? e) Correction factor of 0.5 to account for fibrous nature of peat

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q9 How did you account for the location of boreholes/vane profiles relative to embankment? Did off consider id b borehole/profile h l / fil location 2No. Considered nearest borehole/profile only

0 No.

Considered ‘average’ average of all boreholes/profiles 6 No. Considered trend of all boreholes/profiles, biased towards nearest 0No Other

3 No.

Others a) Looked for the profile showing the lowest strength g b) Pessimistic scenario using judgement c) Statistical analysis Q10

Explain reply to Q9

Explanations E l ti a) Embankments has limited ability to transfer loads, hence ULS must be on lowest strength b) No information given c) Adopted a conservative approach due to uncertainty wrt strength d) Locations plan not given, therefore ‘average’ average soil properties considered.

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

0.0

cuk kPa

10.0

20.0

30.0

-1

R-11

-2

R-58

-3

R-38 R 38

7 No. by eye; 4 No. by stats 1N No. used dS Schneider h id + SD

R-68

NN (m m)

-4 -5 -6 -7 -8 -9

R-24 R-18 R-30 R-82 R 82

mean R-99 R-88 R-105

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

National Annex ¾UK

Design height (m)

¾German ¾Italy

2.5

¾Ireland

¾Portugal P t l

2

¾National ¾Other

std

3 No. 2No. 3 No. 1 No. 1N No. 1No. 1 No.

15 1.5

Design Approaches

1

¾DA1

¾DA1:C2

0.5

¾DA2

¾DA2 DA2* ¾DA3

0 1

2

3

4

5

6

7

8

9

10 11 12

¾DA2

& DA3 ¾Other

2 7 1 1 1 1 1

N No. No. No. No No. No. No. No.

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

γG

γQ

γφ′

γc′

γcu

1.25

1.25

1.25

8

1.0

11

1.0

1.3

1.25

1.4

1.4

58

1.0

1.3

1.25

1.25

1.4

38

1.35

1.5

1.0

1.0

1.0

68

1.35

1.5

1.0

1.0

24

1.35

18

1.0

30

1.3

1.25

1.25

γRv

γRd

1.0

1.0

1.0

1.0

1.4

1.4

1.0

1.0

1.0

1.35

88

1.0

105

1.0

1.25 1.3

1.25

1.25

1.0

1.0

1.4

1.4 1.4

1.8

2.35

0.6

1.4

1.0

H

DA1:C2

1.4

82 99

DA DA3 3

1.0

1.35

γRh

DA1 C1 & C2

1.9

DA1 C1 &C2

1.6

DA2

1.7

DA1.C2

2.0

DA2&3

1.75

Stat

2.1

DA2

0.96

1.1

DA1.C2

2.2

1.1

DA1.C2

1.1/1.4

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

γG

γQ

γφ′

γc′

γcu

58

1.0

1.3

1.25

1.25

1.4

38

1.0

1.3

1.25

1.25

1.4

68

10 1.0

13 1.3

1 25 1.25

1 25 1.25

γRv

γRh

γRd

8 11 1.4 1.0

1.0

1.0

24 18 30

1.0

1.25

1.25

82 99 88 105 2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q 19 Other assumptions

Q20 What additional data required?

¾GWL

¾GWL

¾Mohr-Coulomb

¾Deformability

for fill & S d undrained Sand; d i d ffor peat & topsoil ¾Base

& Piez data

¾Other

or CPT

tests on peat eg DMT

of embankment 13m wide and IP=20, no correction

¾Correction

¾Relative

¾IP

position of embankment and FV

of soil

factor (4 No.)

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q21 – How conservative your previous national practice

Q22 – How conservative EC7

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Q23 – How does EC7 compare with previous national practice.

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

¾Local

experience of reduction required in cuvane (2 No No.))

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Applied pp correction factor of 0.8 to cuvane to get cu-derived Benchmark cuk values kPa 0.0

5.0

10.0

15.0

20.0

cuk kPa

25.0

0.0

-1

-1

-2

-2

-3

-5 -6

FVT1

4 -4

FVT2 FVT3 FVT4 FVT5

NN (m)

NN (m)

-4 4

-3

-5

5.0

10.0

15.0

20.0

25.0 R-11 R-58 R-38 R-68 R 24 R-24 R-18 R-30

-6

Benchmark cuk -7

-7

-8

-8

R-82

mean R-99 R-88 R-105

-9

-9

Benchm

ark cu;k

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Methods of analysis y Method of slices 2 No. Branch-Hansen 1 No.

Design height (m) 2.5

2 2.5 15 1.5

2 1.5

1

Initial data

1

B Benchmark h k

0.5 0.5

0 1

0 1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16

2

3

4

Comparison of individual contributor

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Simple case, assuming no surcharge load.

τ mob

' c' c' Tanφ 'k ' Tanφ = +N = + N' F F γ m;mob γ m;mob

γ m;mob

1 = WSi α ∑ γ GWSin

[ck' b + (γ GW − γ G ub)Tanϕ k' ]Secα ∑ TanαTanφ 'k 1+

γ m;mob

From SLOPE/W Manual

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

cu;d=cu;k/1.4 /1 4 using i b benchmark h k values l Bishop’s method of slices Design height = 1.6m

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Bearing capacity – simplified relationship Approx- dealing with stresses (FORCES ?) γGγH≤ (5.14cu;k/γcu)/RR;e ?

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

¾Correlation

factors and local experience

¾Effect

¾Use

¾Tension

of bearing capacity equations (Table A.14 , earth resistance and γR;e) ¾DA1.C2

of different calculation models.

cracks in embankment?

versus DA3

¾Differences

in application of partial factors 2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010

Dr Andrew Bond L i M Lovisa Moritz i - Assistant A i R Reporter B Bernd dS Schuppener h - Advisor Ad i

2nd International Workshop on Evaluation of Eurocode 7, Pavia, Italy, April 2010