Sidsel Stabell - danskgeotekniskforening.dk · Geoteknisk Stratigrafi 6 18-03-2010 Sidsel Stabell Nomenclature Soil unit FY1 Organic fill (peat / topsoil) FY2 Fill, predominantly

# Cityringen

Geotekniske Forhold

Sidsel Stabell

COWI ARUP SYSTRA JV

118-03-2010

Foto: Roy William Gabrielsen

Præsentation#

Purpose of the geotechnical investigations

Extend knowledge of geotechnical conditions

Plan and adjust alignment

Tender design

Assist the Contractor in carrying out his design

221-04-2010 Sidsel Stabell

Præsentation#

Knowledge basis

approx. 500 boreholes

Index and in-situ testing – soil

Rock element testing

Advanced laboratory testing

Advanced field testing

Background data from previous projects in the Copenhagen area


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Deliverables

Project Information

Present available data

Background information on Danish practice

Knowledge of geological background and site specific conditions

PI-5: Project Information Soil and Rick Mechanics

PI-6: Project Information Site Specific Conditions

Only derived values – not intended to be used for the design


Præsentation#

Concepts and interpretation methods

Interpretation methods based on European practice and Eurocode

Description of Danish practice

Guidelines on interpretation of laboratory testing on overconsolidated soils.


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Geoteknisk Stratigrafi


Nomenclature Soil unit

FY1 Organic fill (peat / topsoil)

FY2 Fill, predominantly sand

FY3 Fill, predominantly clay (uncompacted or compaction unknown)

FY4 Fill, predominantly clay (compacted)

PG1 Organic deposits (peat / gyttja)

PG2 / SS - and late glacial marine and freshwater sand / gravel

PG3 / SL - and late glacial marine and freshwater clay / silt

DS / DG Meltwater sand / gravel

DL / DI Meltwater clay / silt

ML1 Upper clay till

MS / MG Sand till / gravel till

ML2 Lower clay till

PK / PL / PI / PS Paleocene (Greensand) deposits

CL Upper glacially disturbed limestone

UCL Limestone

MCL Middle Limestone

LCL Limestone

BZ Bryozoan Limestone

Præsentation#

Index and in-situ testing - soil

Density measurements

Water content

Undrained shear strength (field vane test)

Plasticity limit

Liquid limit

N-values from SPT tests


Summary of grading for meltwater units (Venn diagram)

0.001 0.01 0.1 1 10 100Grain size [mm]

0

20

40

60

80

100

Pe

rce

nta

ge

[%

]

Clay Silt Sand Gravel Boulder

Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse

Summary of grading for all meltwater units (grain size distribution curves)

Plasticity index vs. liquid limit for Meltwater clay

Symbols Unit Number of tests

Average 5 %Fractile

95 %Fractile

Weight Density g [kN/m3] 3 21 - -

Water content w [%] 43 17 16 19

Plasticity limit Ip [%] 14 20 14 27

Liquid limit wL [%] 14 27 29 45

Undrained shear strength, field vane test

cfv [kPa] 28 304 229 378

SPT N [-] 25 58 49 66

Præsentation#

Rock element testing and inferred rock mass

Density measurements

Water Content

Unconfined compressive strength

Brazilian tensile strength test

Geological description both directly on the recovered core and from Optical and Acoustical Televiewer logs


Præsentation#



Symbols Unit Number of tests Average 5 %Fractile

95 %Fractile

Weight Density g [kN/m3] 2737 21 21 21

Water content w [%] 2806 18.5 18 19

Limestone structure andjoint description

UnconfinedcompressionStrength

c (MPa)

GeologicalStrength

IndexGSI

Frictionangle

'

(deg.)

Cohesion

c' (kPa)

Modulus of deformation

Em (MPa)

Blocky with fair surface condition

6.97 55 45.4 126 2845

Very blocky-interlocked undisturbed mass with multifaceted angular blocks formed by 4 or more joint sets with fair surface conditions

6.97 45 42.7 93 1559

Very blocky-interlocked undisturbed mass with multifaceted angular blocks formed by 4 or more joint sets with fair surface conditions

4

(Mean value of slightly indurated limestone with a density of =

2.1 Mg/m3)

45 38.9 70 895

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Præsentation#

Advanced laboratory testing


Test Type Abbreviation

anisotropically consolidated undrained triaxial tests, clay till / greensand

CAU

anisotropically consolidated drained tests on reconstituted samples of sand and gravel

CAD

isotropically consolidated drained tests on reconstituted samples of sand and gravel

CID

multiple stage anisotropically consolidated drained unloading tests on clay/clay till

MACD

anisotropically consolidated drained triaxial tests, limestone

CAD

Oedometer tests OED

Præsentation#

Advanced field testing, soil and rock

Seismic down-hole test

Pressuremeter tests

Vertical seismic profiling -Sonic logging

Optical and acoustic televiewer


Præsentation#


Seismic down-hole test

Measure in situ variation of the shear (S-) wave velocity with depth → shear modulus


0 500 1000 1500

0

5

10

15

20

25

30

35

S-wave velocity (m/s)

Depth

(m

)

Borehole C0936

0 500 1000 1500 2000 2500 3000 3500 4000

0

5

10

15

20

25

30

35

Shear modulus, G0 (MPa)

Depth

(m

)

Borehole C0936

Præsentation#


Pressuremeter tests

Evaluating Stiffness properties, but may be inferred on the strength properties

Most test done in H2 material

Correlation with Vertical Seismic profile (VSP)


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Conclusion

Extensive knowledge of geotechnical conditions in Copenhagen

Variability in undrained shear strength, for the Clay till

Limestone conditions

Greensand formations

Alignment justifications

Tender design input.


Documents

Sidsel Stabell - danskgeotekniskforening.dk · Geoteknisk Stratigrafi 6 18-03-2010 Sidsel Stabell Nomenclature Soil unit FY1 Organic fill (peat / topsoil) FY2 Fill, predominantly