ISSMGE Technical Committee 17 - Ground improvement. Site visit

Transcription

ISSMGE Technical Committee 17 - Ground improvement.
Site visit and Meeting 4 of the TC 17 Members : Minutes
Date : Friday 19th September 2008
Place : Holiday Inn – 15, Rue Edouard Vaillant, 37000 Tours
Present:
TC 17 Members: Serge Varaksin (France), Jan Maertens (Belgium),
Noel Huybrechts (Belgium), Michel Chopin (France), Philippe Héry
(France), John Sankey (USA)
Invited: B. Simon (Terrasol) and Magali Boudot(Ménard))
Apologised: Juan Baez (USA), Mounir Bouassida (Tunisia), Jian Chu (Singapore),
ran, Bob Essler (UK), Stephanie Glendinning (UK), Göran Holm
(Sweden), Chris Jenner (UK), Mina Karstunen (UK), Leena KorkialaTanttu (Finland), M.R. Madhav (India), Jun Otani (Japan), Alexandro
Pinto (Portugal), Annand Puppala (USA), Helmut Schweiger (Austria),
Shi Jian Yong (China), Almer van der Stoel (The Netherlands), Daniel
Verastegui (Belgium), Jean Claude Verbrugge (Belgium), Ken Watts
(UK)
SITE VISIT (AM)
Under guidance of Miss Magalie Boudot the “Tours ring road project” is visited.
Within the framework of this project a high number of rigid inclusions is being
realized by Ménard Soltraitement. A part of the experimental program of the French
research project A.S.I.R.I. (see further) is carried out on this specific site.
TC 17 MEETING (PM)
After an excellent lunch offered by Ménard, the TC 17 meeting is held.
1. Introduction and presentations CMC and A.S.I.R.I
S. Varaksin welcomes the present TC17 members.
S. Varaksin presents more details about the visited site and the (CMC) rigid inclusions
design method in particular. The presentation is given in Annex 1 of these minutes.
Mr. Bruno Simon, Director of the scientific and technical committee of the French
research project on rigid inclusions “A.S.I.R.I.” highlights the program. The
presentation of Mr. Simon is given in Annex 2 of these minutes.
2. TC 17 Activities : progress
Working Group A (coordinator H. Schweiger)
The report of WG A has been posted on the TC 17 website.
Working Group B
The co-ordination of WGB has been taken over by the chairmen. A description of
several techniques is available. Some techniques have still to be worked out by J.
Maertens (JMA).
Working Group C (coordinator J. Chu)
Working Group C runs well. Reports are published on the website.
Working Group D (coordinators R. Essler and M. Kitazume)
Information of WG D has been published on the website.
Working Group E (coordinator M. Chopin)
Mr. Chopin explains that a first draft of the WG E report is available. However the
document need some corrections.
The chairmen ask however to put the existing documents already as a draft version on
the website (MC).
Working Group F (coordinator Ph. Héry)
The report of WG F has been published on the website.
Working Group G (coordinator T. Durgunoglu)
No documents available until now.
Mr. Durgunoglu promised his contribution soon (TD).
Country reports
The following country reports are already available on the website
• USA (R. Lopez & K. Stokoe)
• Germany (J. Wehr & W. Sondermann)
• Turkey (T. Durgunoglu)
• Japan (M. Kitazume)
• France (C. Plomteux)
• Malaysia (Ooi Teik Aun)
Since July 2008 the following reports were received and will be put soon on the
website
• Australia (P. Wong)
• Belgium (D. Verastegui)
• China 1 (G. Zheng)
• China 2 (J.Y. Shi)
• Finland (L. Korkiala-Tanttu)
• Greece (Th. Platis)
• Singapore (J. Chu)
• The Netherlands (A. van der Stoel)
With regard to the report of J. Chu, J. Maertens propose to ask him to add references
that are mentioned in the text (NH).
In the next mailing, the TC17 members that did not yet deliver a country report, will
be asked again to deliver it soon (NH).
J. Maertens suggests to compile all the national reports in a book.
After discussion it is decided that the heterogeneity of such a publication would be too
big.
It is however decided to make a summary of all the TC 17 work that has been carried
out and to provide website references. N. Huybrechts will make a concept before the
Next TC 17 meeting (NH).
3.TC 17 – Specialty Session - ICSMGE Alexandria 2009
TC 17 will organize a specialty session in Alexandria. Meanwhile it has been decided
that this session takes place on Wednesday 7 October at 17h30. It is estimated that
the session will last for 2.5 to 3 hours.
The following scheme is proposed:
Block 1 (duration 1h 20 minutes) : Rigid inclusions - recent developments
Presentation 1 (20 minutes) : National Research project in France - ASIRI :
Soil Improvement using pile-like inclusions, Mr. B. Simon, Terrasol (France)
Presentation 2 (20 minutes) : Contribution from USA with regard to rigid
inclusions (speaker to be assigned)
Presentation 3 (20 minutes) : Contribution from China with regard to rigid
inclusions (speaker to be assigned)
Discussion (20 minutes)
Pause (15 minutes)
Block 2 (duration 1h20 minutes): Recent advances in conception of ground
improvement techniques
Introduction (10 minutes) : Overview ISSMGE TC 17 activities; S. Varaksin
& J. Maertens, TC 17 Chairmen
Presentation 1 (20 minutes) : Overview of the results of the AMGISS project
(Advanced Methods for Ground Improvement in Soft Soils) , H. Schweiger,
TU Graz (Austria)
Presentation 2 (20 minutes) : Caïro metro line 3 – Risk mitigation and
experiences, M. Chopin (France).
Presentation 3 (20 minutes) : Mechanically Stabilized Earth composite
material or fill with reinforcements? Consequences on design and justification,
N. Freitag (France? )
Discussion (10 minutes)
With regard to a USA speaker S. Varaksin will transmit a possible candidate (SV).
With regard to a Chinese speaker, S. Varaksin will ask advice from J. Chu (SV).
B. Simon suggests Mr. Charles WW.Ng as possible speaker. Mr. WW.Ng published
recently about the performance of a geogrid reinforcement. in the Journal of
Geotechnical en Geoenvironmental engineering (December 2007 – p.1483 – see
Annex 3) (Action by who?)
The topic that will be presented by Mr Freitag will be transmitted by Mr. Héry (PhH)
4. Website (www.bbri.be/go/tc17)
S. Varksin will update the reference list (SV). It is asked to the TC 17 secretary to
add a list of relevant EN standards (NH).
It is agreed that the contributions (presentations) at the TC 17 Session during the IS
Kyushu 2007 should be on the website. Mr. Héry will collect these presentations
(meanwhile a report on the TC 17 Session has been received) (phH).
It is decided that general information about ground improvement can be posted on the
TC 17 website in the rubric “Documents/Other interesting ground Improvement
documents”, as long as it concerns no commercial information.
Events/Conferences can be announced on the website as long as TC 17 members are
involved (e.g. the Okiwana Deep mixing conference in 2009).
The website will be updated as soon as possible (NH).
5. Questions
The next TC 17 meeting will be organised before the ICSMGE in Alexandria. March
or April 2009 seems appropriate. An occasion and place will be looked for (SV &
JMA).
The Chairmen thanks the TC 17 members and the invited speakers for their presence
and their efforts and closes the meeting.
ANNEX 1
Journée Technique Géotechnique
« La géotechnique est au cœur de nos projets
4
Juin
2008
Amélioration des sols par inclusions
rigides
Cas d’un remblai
Pezot / Guespereau / Bic
3. Projet de CMC sous ouvrage en terre
1 – Transfert de la charge au sol
cmc
Remblai
Sol compressible
2
2 – La charge se répartie entre le sol et les inclusions
(générant du tassement négatif)
CMC
Remblai
Sol compressible
3
3 – Tassement de l’inclusion et
transfert de la charge au substratum
(résistance de pointe + tassement positif)
Remblai
Sol compressible
4
4 – État final = répartition optimale entre sol et inclusion
Remblai
Sol compressible
5
Charge du remblai
Matelas de répartition
Concentration de contrainte
Concentration de contrainte
6
Effet de voûte entre les inclusions
CMC
CMC
Contrainte résiduelle
5 à 50 % de la charge totale
FIN DES TRAVAUX
5 km
ORIGINES DES TRAVAUX
7
Vue du tracé en service
8
Coupe type de l’ouvrage
9
10
11
12
Profil en long géotechnique
13
Exemple d’une coupe de calcul modélisée sous Plaxis
14
Exemple d’un extrait de plan du maillage
15
1. CALCUL EN DEFORMATION
• Sans pondération de charge,
• Estimation du module de déformation vertical (pressiomètre,
corrélation via CPT)
• Tassement résiduel.
2. CALCUL A LA RUPTURE
• Sollicitation dans les inclusions,
• Capacité portante du substratum,
• Stabilité d’ensemble du massif.
3. PARAMETRES DE CALCUL A DETERMINER
• Maillage du réseau d’inclusion,
• Diamètre des inclusions,
• Epaisseur et module du matelas de répartition,
• Ancrage éventuel des inclusions.
16
1 – Méthode aux éléments finis à l’échelle locale => calcul axisymétrique
Colonne centrale en
condition oedométrique
2 – Méthode aux éléments finis à l’échelle globale => calcul 2D
Colonne en bord
de talus en condition
dissymétrique
17
Donnée de calcul
18
1 – Critère de déformation
2 – Critère de résistance
Point neutre
Contrainte normale = 3,24 MPa
(dia. 420 mm => 45 t max. adm)
19
Colonne modélisée par un élément “mur” de raideur axiale et de flexion équivalente
EYeq Aeq = EY ×
π × D2
4× e
EYeq I eq = EY ×
Sol compressible modélisé en Mohr-coulomb => Eysol = 5 MPa
Présentation du modèle 2D
20
π × D4
64 × e
Cone de rupture
Remblai en Mohr-coulomb
C’ = 5 kPa / φ’ = 30°
Colonne modélisée par élément “mur” de raideur axiale et de flexion
infinitésimale (10 –10) autour d’un sol équivalent de diamètre équivalent
Déformation verticale
21
Cone de rupture
Remblai en Mohr-coulomb
C’ = 5 kPa / φ’ = 30°
Déformation horizontale
22
1. Chargement dissymétrique
=> un déplacement max. en tête d’inclusion
2. Déplacement en tête est imposé
=> déformation et de la flexion dans les inclusions de rive
23
1 – Le déplacement horizontal en tête d’inclusion est imposé et dépend de la
géométrie du remblai et de la butée disponible
2 – La densité d’inclusion ne réduit pas la valeur du déplacement horizontal
3 – Pour un déplacement imposé => déformation imposée => flexion imposée
4 – Pour satisfaire la condition de zéro traction => Effort normal satisfaisant
5 – Augmenter la maille dans la pente du talus permet de reprendre + de N
6 – Verification des inclusions à la flexion composée
7 – Verification de l’excentrement de la résultante des efforts
Interprétation des résultats
24
N M
±
S I
v
M D
e=
≤
N
8
σ1 =
Variation des contraintes
normales N / S
Variation des contraintes de
flexion M / (I/v)
Vérifications des sollicitations dans les inclusions
25
Essai de portance poussé à 1,5 x Q els
26
AVANTAGES DES INCLUSIONS RIGIDES
1 – Augmente la rigidité verticale du sol naturel
2 – Réduit les tassements absolus (sans inclusion) à des tassements résiduels
post construction (avec inclusion) limités et compatible avec
le futur ouvrage
3 – Augmente la résistance au cisaillement vis-à-vis de la stabilité,
densification du sol contre le risque de liquéfaction
4 – Solution rapide comparativement au temps nécessaire à une consolidation
par du pré-chargement
5 – Solution envisageable en milieu urbain, près d’ouvrages existants
27
ANNEX 2
Amélioration des Sols par Inclusions Rigides
verticales
Soil improvement using pile-like inclusions
Bruno SIMON
TC17 meeting 4, Tours, September19th, 2008
A compound foundation system
9 Stiff inclusions
9 Pile caps
9 Reinforcement (occasionally)
9 Granular mattress
9 Floor slab (occasionally)
… Pile supported earth platform
… Piled embankment
2
Development on the last 30 years
• Piled embankments for roads and railways
• Pile supported earth platforms
– Floor slabs and rafts (warehouses, stores)
– Bridge abutments
– Tramway lanes
– Dockyards
• …...
• Foundations of the Rion-Antirion cable-stayed bridge
3
Main advantages
• Loading can be partly carried by soil
• No spoil if displacement technique used
• Connection between foundation and structure made
easy by the transfer layer
• Shorter period of construction than with preloading
• Good seismic behaviour (ductility)
4
Present situation
• No national standard
– not a widely accepted technique for common works
• A wide range of design methods is used
– No comprehensive model of all mechanisms involved
• Soil investigations often inappropriate
5
ASIRI project (2005- 2009)
2.4 M € state and industry funded research project
• Led by a non profit organization (IREX)
– With managing and scientific committees
• Independent network of owners, consultants,
contractors and academics
• Civil and Urban Engineering Research label
6
ASIRI project (2005- 2009)
FNTP / Fe de r a t i on
M a î t r e s d ' o u v r a g e / Own e r s
M a î t r e s d ' œu v r e / En g i n e e r s
C o n su l t a n t s
En t r e p r i se s g én ér a l e s
/ Ge n e r a l c o n t r a c t o r s
L a b o r a t o i r e s, U n i v e r si t és
/ Ac a de mi c s
En t r e p r i se s sp éc i a l i sée s
/ F o u n d a t i o n sp e c i a l i st s
0
2
4
6
8
10
12
14
• 39 members subscribing 155 k€/year
• 9 PhD in progress (4 with support of industrial partners)
7
General organisation and planning
Themes
2006
2007
2009
nk
a
b
m
E nt
me
r
o
e
o
Fl llagb
Dasla
1-Full scale
experiments
2008
2 –Monitored works
3 –Laboratory and
physical modelling
ch
a
te
c
ra
tio
a
riz
n
& ting
e
ugr tes
f
i
tr be
n
Ceham
c
4 –Numerical
modelling
8
Président
F. Schlosser
Vice -Président O. Combarieu
Directeur technique B. Simon
(Terrasol)
Theme 1
Theme 2
Theme 3
Theme 4
L. Briançon
E. Haza
L. Thorel
D. Dias
(CNAM)
(CETE)
(LCPC)
(INSA Lyon)
Theme 5 (Recommendations) : O. Combarieu
9
St Ouen full scale experiment (2006)
• Floor slab foundation
Displacement IR
Displacement IR
Non displacement IR
CNAM PhD work J. Andromeda
10
Contrainte totale (kPa) .
Load transfer onto inclusion heads
2000
Phase 2
CPT4D
1500
1000
Phase 1
CPT3D
500
CPT2D
0
0
100
200
300
400
Durée (jours)
11
Settlement at base of the granular layer
10 m
4m
3D
2D
6m
8m
4D
1D
CA
12
Settlement at pile head elevation
• Plot 1D (unreinforced)
0
50
100
150
200
250
(j)
0
-10
Tassement (mm)
-20
-30
-40
-50
-60
-70
-80
13
Settlement at pile head elevation
• Differential settlement / inclusion heads
0
50
100
150
200
250
300
350
400
450
0
Tassement différentiel (mm) .
-10
-20
-30
2D
3D
4D
-40
-50
-60
-70
-80
14
Chelles full scale experiment(2007)
20cm
GGRU
20cm
20cm
GGRL
15cm
15cm
20cm
8m
5m
2R
2m
GTX
8m
2m
8m
4R
3R
0m
2m
7m
1R
3:2
Remblai argileux w = 30%
Argile (Cc/1+e0) = 0.25
w = 60%
Sable argileux
(Cc/1+e0) = 0.1
w = 30%
-5 m
-10 m
Substratum
s = 2m
L = 52 m
15
Chelles full scale experiment (2007)
• Load transfer onto inclusions
3000
CPT5
Construction
du remblai
Contrainte (kPa)
2500
2R
2000
1500
CPT1
3R
CPT9
CPT5
CPT10
4R
CPT14
CPT10
1000
CPT1
500
CPT14
0
21/8
5/9
20/9
5/10 20/10 4/11 19/11 4/12 19/12
CPT9
3/1
18/1
Dates
16
2/2
Monitoring of on construction works
• Interchange (Chelles, 2007-2008)
P4
P3
P1
P2
• North western ring road(Tours, 2008)
– 4 to 5 m high fill+ 10 m phonic barrier close to an existing
railway line
– 25000 inclusions (135000 ml)
17
– ASIRI monitoring included in the Client specifications
Transfer layer material (Saint Ouen)
ρd=85 % ρd,opm
CERMES
18
Physical and laboratory testing
• 2D analogical soil (Jenck, 2005)
H
S
URGC/INSA Lyon
19
Calibration chamber testing (scale 1/5)
CERMES thèse Anh Quan Dinh
Calibration chamber testing (scale1/5)
• Influence of the transfer layer grain-size distribution
HM = 10 cm
5000
20
Test 9 - Micro-ballast 10/16
Test 6 - Gravier d'Hostun 2/4
16
3000
Efficacité (%)
Force (N)
4000
2000
1000
12
8
Test 6 - Gravier d'Hostun 2/4
4
0
0
0
20
40
60
80
Contrainte appliquée (kPa)
100
120
0
20
40
60
80
Contrainte appliquée (kPa)
CERMES PhD work Anh Quan Dinh
100
120
21
Centrifugeuse (Echelle 1/28)
• Comportement maille élémentaire
LCPC Nantes Thèse Gaelle Beaudouin
22
Centrifugeuse (Echelle 1/28)
Numerical modelling
• 3D continuum model
Reference model
• Parametrical study
– Geometry
– Constitutive model
• To simulate physical tests
• To evaluate
– Analytical tools
– 2D axisymmetric models
– Biphasic models
URGC/INSA Lyon
24
Reference case : piled embankment
5m
5m
γ = 15 kN/m3
2.5 m
φ= 30° ψ = 0 c’ = 0
E = 5 MPa υ = 0.3 URGC/INSA Lyon
25
Reference case : piled embankment
30 mm
Settlement
Stresses
5m
2 mm
5m
URGC/INSA Lyon
26
Reference case : floor slab
qo
0,5 m
5m
2.5 m
URGC/INSA Lyon
27
Reference case : floor slab
12,8 mm
0,8 mm
Floor slab
Transfer layer
Inclusion
URGC/INSA Lyon
28
3D discrete numerical modelling
• Clusters (2 connected
elements)
– linear constitutive law of
contact (normal, tangent)
– adhesion (tensile strength)
• Micro-mechanical
parameter values adjusted
to fit triaxial test results
3S-R UJF Grenoble (PhD work B. Chevallier)
29
Displacement field in granular layer during loading - without concrete slab
3S-R UJF Grenoble (PhD work B Chevallier)
Displacement field in granular layer during loading - with concrete slab
31
3S R UJF Grenoble (PhD work B Chevallier)
An analytical approach : Foxta (Taspie+)
Qp(0)
τ
Qs(0)
qsl
Frank et al.
yp-ys
yp
τ
−τ
Terrasol
ys
32
An analytical approach : Foxta (Taspie+)
•
•
Piled embankment
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0
1.8
‐5
Settlement (mm)
Settlement (mm)
0.2
0.4
0.6
0.8
1
1.2
1.4
0
0
reference case CR1
‐10
‐15
‐20
‐25
‐30
‐35
1
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
6
E quivalent fill load (m)
7
8
9
10
Stress reduction ratio
Flac
Taspie+
Dis tanc e to inc lus ion c entre‐line (m)
Stress reduction ratio
Floor slab
Terrasol
reference case CD1
‐5
‐10
‐15
Dis tanc e to inc lus ion c entre‐line(m)
0.8
0.6
0.4
0.2
0
0
20
40
Applied dis tributed load (kP a)
60
33
Benchmark exercise I (Saint Ouen)
• Settlement
34
• Settlement
Plot 4D
0.00
0
R1 (M)
h (mm)
(mm) ..
Δh
Δ
-20
-5.00
-40
R1C (M)
R1 (M) :2,5mm
-60
-10.00
-80
R1C (M) R2
: 3,5mm
(M)
R2 (M) : 11 mm
-15.00
-100
R2C (M) : 18mm
R2C (M)
-120
-20.00
-140
-160
-25.00
-180
-30.00
-200
10 11
11 12
12 13
13 14
14 15
15 16
16 17
17 18
18
11 22 33 44 55 66 77 88 99 10
R1
R1 + 60 jours
R2
R1
R1
R2 + 60 jours
35
• Pile head vertical stress
3300
3000
Remblai 2
Remblai 2C
R2 (M)
R2+19 j (M)
R2+60 j (M)
2500
2000
Δσ (kPa) .
3350
4D (CPT4D)
1500
1000
500
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
36
ASIRI Recommendations (2009)
•
•
•
•
•
•
Summary
Description and developments
Mechanisms and behaviour
Conception and design
Investigations and tests
Construction
Specifications and inspections
37
www.irex-asiri.fr
38
ANNEX 3

ISSMGE Technical Committee 17 - Ground improvement. Site visit

Transcription

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