PRESSUREMETER TEST Study case: Rhone Valley Power Plant - - PowerPoint PPT Presentation

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PRESSUREMETER TEST Study case: Rhone Valley Power Plant - - PowerPoint PPT Presentation

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PRESSUREMETER TEST Study case: Rhone Valley Power Plant Presentation for SBGIMR / BVGIRM CHOOSE EXPERTS, FIND P. Debauche & S. Basire PARTNERS PRESSUREMETER TEST STUDY CASE 2 FEBRUARY 2011 TABLE OF CONTENTS 1. Rhone Valley

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SLIDE 1

CHOOSE EXPERTS, FIND PARTNERS

PRESSUREMETER TEST Study case: Rhone Valley – Power Plant

Presentation for SBGIMR / BVGIRM

  • P. Debauche & S. Basire
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SLIDE 2

2

  • 1. Rhone Valley power plant – Situation map
  • 2. Rhone valley geological context
  • 3. Site geological description
  • 4. Power plant foundation layout
  • 5. Required soil investigation depth
  • 6. Recommendations for the spacing and depth of investigation based
  • n E.C. 7
  • 7. Geotechnical soil investigation
  • 8. Foundation design based on Pressumeter test

TABLE OF CONTENTS

FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

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SLIDE 3

RHONE VALLEY POWER PLANT LAYOUT

3 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

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SLIDE 4

RHONE VALLEY GEOLOGI CAL CONTEXT

4 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

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SLIDE 5

SI TE GEOLOGI CAL DESCRI PTI ON

21/02/2011 5 WI NDTURBI NE FOUNDATI ON

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SLIDE 6

6

POWER PLANT FOUNDATI ON LAYOUT

FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

Foundation slab height ~ 5 m Foundation slab diameter ~ 65 m 3300 m²

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SLIDE 7

7

REQUI RED SOI L I NVESTI GATI ON DEPTH

FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

Superficial foundation

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SLIDE 8

8

RECOMMENDATI ONS FOR THE SPACI NG AND DEPTH OF I NVESTI GATI ONS BASED ON E.C. 7

FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

  • For high-rise & industrial structures : grid pattern with

points at 15 m to 40 m distance;

  • For special structures (e.g. machinery foundations, etc) :

2 to 6 investigation points per foundation.

  • For high-rise structures : investigation depth ≥ 3* bf ;

Spacing

  • For raft foundations with several foundation elements

whose effects in deeper strata are superimposed on each

  • ther : investigation depth ≥ 1.5* bB.

Depth

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SLIDE 9

13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 2 4 6 8 10 12 Niveau NGF MPa

Pression de fluage pf Pression limite Pl*

13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 200 400 600 Niveau NGF MPa

Module pressiométrique Em

13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 200 400 600 800 1000 1200 1400 Niveau NGF MPa

Module de Young E (dilatomètre) Module de Coulomb G (dilatomètre)

GEOTECHNI CAL SOI L I NVESTI GATI ON

9 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

NO DATA WI TH CPT PreDrilling 9m 3 m

PRESSI OMETER DI LATOMETER CPT

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SLIDE 10

FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (1)

10 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

I n our case study, the raft foundation is a shallow foundation: According to fascicule 62 – titre V, the limit base stress is provided by the formula

*

.

le p pu

p k Q =

where kp is the bearing factor depending on soil nature (see table here

below)

Limit base pressure qpu

B, L : dimension of foundation D : Depth of the foundation

( )

∫

=

D le e

dz z * pl * p 1 D

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SLIDE 11

11 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (2)

p* le : the soil equivalent net limit pressure under the foundation

  • I n the case of a shallow foundation established on homogeneous soil

layers with a thickness of at least 1.5. B below the base of foundation: P* le = pl* Net limit pressure value prevailing at a thickness of 1.5 B

  • I n the case of a shallow foundation on no homogeneous soil layers

between depths D and D + 1.5 B :.

  • Net limit pressure value in the layers located on D to D + 1.5 B

n n l l le

pl p p p * * . * *

2 1

⋅ ⋅ ⋅ =

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SLIDE 12

In order to calculate the bearing capacity of a shallow foundation, the limit values for the base Qpu have to be multiplied by the following reducing factors, depending on the limit state considered:

12

FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (3)

FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

Serviceability Limit State (SLS) Ultimate Limit State (ULS)

Base strength Qpu 0.33 0.5

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FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (4)

13 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

The calculation of settlement by the pressuremeter method defined in French code (Fascicule 62 Titre V or DTU 13.12) is not applicable for of large dimensions of rafts. Settlement by the pressumerter method is limited to the soles of small sizes (3m x 3m). For raft foundation, finite element model must be performed. I n finite element model, Young modulus must be determinate. I n this studies case Ey is determinated by Dilatometer test and pressiometer test with correlation.

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FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (5)

14 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

The relationship usually used :

Young modulus correlation with pressumeter test

Depth (m) Lithology Geotechnical behavior αM

14 - 20 Marls Natural Rock 1/2 20 - 40 Sandy Marls Normally consolidated Sand 1/3 40 - 80 Marls Natural Rock 1/2 80 - 100 Sandy Marls Normally consolidated Sand 1/3

Selection of rheological coefficient of soil αM:

( )( ) ( )

M M M

E y E

  • ed

E y E

  • ed

E M E α ν ν ν α 74 . ' 1 ' 2 1 ' 1 = − − + = =

With ν’, Poisson coefficient = 0.3

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SLIDE 15

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 200 400 600 800 1000 1200 1400 Niveau MPa

Young Modulus

Module de Young Ey (dilatomètre) Module de Young Ey modélisé selon la formule : Ey=0.74EM/a Module pressiométrique

FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (6)

15 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

Young modulus correlation with pressumeter test

Significant difference between Young's modulus measured by the dilatometer tests and Young's modulus deducted by the pressuremeter tests :

  • Limits of correlations ?

See article O. Combarieux in “Revue française de la géotechnique N° 114”: « L’usage des modules de déformation en géotechnique » He defied for circular slab the following relationship Where : R is the radius of the foundation = 32.5 m R0 = 0.3

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SLIDE 16

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 200 400 600 800 1000 1200 1400 Niveau MPa

Young Modulus

Module de Young Ey (dilatomètre) Module de Young Ey modélisé selon la formule : Ey=0.74EM/a Module pressiométrique 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 200 400 600 800 1000 1200 1400 Niveau MPa

Young Modulus O.COMBARIEUX Method

Module de Young Ey (dilatomètre) Module de Young Ey modélisé selon la formule : Ey=0.32((R/R0)^(1-a)+a/2) où a=1 et 2/3 Module de Young Ey modélisé selon la formule : Ey=0.32((R/R0)^(1-a)+a/2) où a=1/2 et 1/3

FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (7)

16 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

Young modulus correlation with pressumeter test

  • Problematic of choice of

rheological soil parameters α With the “O. Combarieux method” for the correlation the coefficient α= 1 (behaviour of an over consolidated clay) α= 2/ 3 (behaviour of a consolidated clay) Same differences at great deep with this 2 method of correlation : Limit of validity of the results of pressuremeter tests at great depth?

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SLIDE 17

FOUNDATI ON DESI GN BASED ON PRESSUREMETER TEST (7)

17 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE

Calculation of settlement with finite element model (SAP)

Estimation of settlement with load uniformly distributed over the raft of 6.3 Bar, is equal to 7.8 cm at the center of the raft Flexible Model

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THANKS FOR YOUR ATTENTION.

18 FEBRUARY 2011 PRESSUREMETER TEST – STUDY CASE