principles for tunnel design 20th to 21st april 2017 kuala ... · numerical methods- plaxis, flac,...

Principles for Tunnel Design

20th to 21st April 2017– Kuala Lumpur

Settlement prediction and control in urban tunneling Dr. Noppadol Phien-wej

Asian Institute of Technology & Thailand Underground & Tunnelling Group

Contents

• Urban tunnelling

• Construction methods

• Characteristics of ground movement

• Prediction methods • Empirical Gaussian method • Numerical methods

• Responses of buildings to ground movements & damage level

• Handling of potential impacts of tunnel ground movements in tunnelling project

• Case studies

Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

Characteristics

• Shallow depth tunnelling • Soft ground tunnelling • Ground water • Work in limited spaces • Existing surface and subsurface structures & Utilities •Potential damages to third parties

Geotechnical Aspects

• Excavation method and support design • Maintain stability during excavation • Minimize ground movements & impacts on existing structures

Urban Tunnelling


Methods of Tunnel Construction in Soft Ground

• Cut & Cover Construction

• Tunnelling • Shield Tunnelling

• Conventional Tunnelling –

Shotcrete & steel arch (NATM)

Ground Movements and Instability in Urban Tunnelling


Tunnel Induced Ground Movement

10

15

20

25

30

x

-20

-10

0

10

20

y

-0.03

-0.02

-0.01

0

Settlement,HmL

-0.03

-0.02

-0.01

0

Settlement,HmL

Surface Settlement Trough


Ground movement vectors induced by tunnel excavation (Physical Models)

Wide Narrow


Methods of evaluation of tunneling induced ground movement

Empirical method : Peck (1969)- Gaussian, O’Reilly & News (1982), Mair et al (1997),

etc. Analytical method:- Sagaseta (1987), Verruijt

and Booker (1996), Loganathan and Poulos (1998), etc.

Numerical methods- PLAXIS, FLAC, MIDAS II,

etc.


Empirical methods

Analytical methods

Loganathan & Poulos (1998)

Peck’s Gaussian Surface Settlement Trough (Green Field)

Empirical Method Peck (1969)’s Settlement Trough


Idealized transverse surface settlement trough profile (after O’Reilly & New 1982)


Movement and volume of ground loss( Uriel,1989)

VL = volume of ground loss

For undrained ground, Vs ≈ VL


O’Rielly and New (1982)


GROUND LOSS

20

Ground movement induced by tunneling

TBM

ab

cd

e

segmental lining

Set

tlem

ents

a. ahead and above the head

b. along the TBM

c. induced at the tail void

d. due to lining deflection

e. due to long term settlement


Load factor =gh/5c


Numerical Analysis

• FEM, FDA, BEM

• 2D versus 3D



Ground reaction curve Pressure-Contraction

Applied pressure method (Moller, 2006) Stress reduction method

Plaxis 2D : Input methods of simulating tunnel excavation - Line contraction method - Stress reduction method -Applied pressure method

Line contraction method


Hardening-soil model

Mohr-Coulomb model


After PLAXIS Traning Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

Line Contraction 1% Volume Loss Max Settlement 18 mm

Stress Reduction 1% Volume Loss Max Settlement 24 mm

Bangkok Case – Hardening Soil


After PLAXIS Training Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

M4 metroline in Shanghai Grand Duomo-Milan

Responses of Structures to Ground Movement From Tunnelling


Responses of Structures to Ground Movement From Tunnelling


Building Distortion induced by

Tunneling


Damage criteria for Brick Wall Building Cording (1981)

Damage criteria for Brick Wall Building

Burland (1997)

BULIDING DAMAGE CLASSIFICATION OF BRICK BUILDING

(after Burland et al, 1997)

Description of Typical Damage Approx. Crack Width

(mm)

From Excavation & Tunnelling Degree of Damage Risk Category

Max. Tensile Strain % Settlement Ratio

S / L

Hairline cracks - Less than 0.05 < 1:1000 Negligible 0

Fine cracks easily treated during normal redecoration.

Perhaps isolated slight fracture in building. Crack in

exterior brickwork visible upon close inspection

0.1 to 1.0 0.05 to 0.075 1:1000 to 1:500 Very slight 1

Crack easily filled. Redecoration probably required.

Several slight fractures inside the building. Exterior

cracks visible. Some repairing may be required for

weather tightness. Door and windows may be stick

slightly.

1.0 to 5.0 0.05 to 0.15 1:500 to 1:300 Slight 2

Cracks may require cutting out and patching. Recurrent

cracks can be masked by suitable linings. Tuck-

pointing and possible replacement of small amount

exterior brickwork may be required. Doors and

windows sticking. Utility services may be interrupted.

Weathered tightness after impaired.

5.0 to 15.0 or a number

of cracks grater than 3.0

0.15 to 0.3 1:300 to 1:200 Moderate 3

Extensive repair involving removal and replacement of

sections of walls, especially over doors and windows

required. Windows and doors frames distorted. Floor

slopes noticeably. Some loss of bearing in beams.

Utility services disrupted.

15.0 to 25.0 (depend on

number of cracks also)

Greater than 0.3 1:200 to 1:100 Severe 4

Major repair required involving partial or complete

reconstruction. Beams lose bearing, walls lean badly

and require shoring. Windows broken by distortion.

Danger of instability.

> 25.0 (depend on

number of cracks also)

- > 1:200

> 1:100

Very Severe 5

Actual Response of Building:

Soil Structure Interaction

Effect of Width of Building on Responses


Actual Response of Building


TUNNELLING NEAR TO PILE FOUNDATION

Piles

Pile cap

Building

Columns

Tunnelling in progress

Downdrag

Soil movementNSF

Resisting

force

Lateral

deflection

Negative skin

friction (NSF)

After Yong (2004)

RESPONSE OF PILE FOUNDATION TO TUNNELLING

• Pile lateral deflection and bending moment • Transversely (Perpendicular to tunnel advancing direction)

• Longitudinally (Parallel to tunnel advancing direction)

• Tensile force in pile • Possible near pile head depending on the type of restraint

• Dragload (additional axial force) in pile • Above tunnel springline or invert level

• Pile settlement • Due to downdrag

• The type of response depends on the tunnel-pile relative position

www.ait.ac.th

Bangkok MWA G-MC-7: Section 10+100

2D Analysis

3D Analysis

Soil movement trajectories

Greenfield

With Piles

Pile-equivalent wall in 2D blocking ground movement

Analysis of Piled Foundation Responses – 3D Numerical Analysis

Mesh

3D: 15 Node wedge element

2D: 15 Node Triangular element

Soil Model

Linear perfectly plastic-The Mohr Coulomb model

Analysis type – Undrained effective stress analysis using effective strength parameters

The at-rest coefficient of earth pressure Ko was set as 0.5

2D mesh

3D mesh


Ground Movement Trajectory around a Tunnel Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

MRT NORTH-EAST LINE C704 - Singapore GEOLOGY AND GROUND CONDITIONS

• Contract 704 package includes • 1.9km long viaduct bridge

• 2 abutments and 39 piers

• Supported on pile foundation

• Parallel to twin tunnel configuration

• Piles location in between twin tunnels

• Geological profile • Residual soil (Bukit Timah Granite)

• Reddish brown, sandy silty Clay

• SPT-N ranging from 20 to 50 in the tunnelling zone

Residual soil (SPT-N <15)

Clayey Silt and Silty Clay

(Top 1.5m consist of fill)

Residual soil

(SPT-N 15 to 30)


Completely weathered Granite

(SPT-N 30 to 50)


Completely weathered Granite

(SPT-N 50 to 100)


PILE

GROUP

TUNNEL

44m

62m

21m

30m

0m

3m

16m

PIER 20

After Yong (2004)


MRT NORTH-EAST LINE C704 MONITORING SCHEME AND LAYOUT

• Pile foundation • Bored pile with base grouting • 1.2m diameter • Lp up to 60m length • 4 piles/group

• Tunnel • EPB shield machine • Diameter : 6.5m • h = 16 to 25m.b.g.l.

• Tunnel-pile position • Clear dist. = 1.6 to 4.4m • Lp/h ratio = 1.3 to 2.9

• Instrumentations • Six instrumented sections • Two instrumented piles in each section • VW strain gauge (in-pile) • Inclinometer • Magnetic extensometer • Settlement marker • Piezometer PIER 20

After Yong (2004)

FIELD MONITORING RESULTS AT PIER 20

• Development of axial force in piles • Max. dragload due to SB = 3400kN (front pile) and 2600kN (rear pile)

• Dragload increasing with depth up to tunnel level

Axial force vs. time for pile P1 (front pile)

Variation of axial force with depth

-ve denotes compressive force

After Yong (2004) Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

THREE-DIMENSIONAL FINITE ELEMENT MESH

• ABAQUS 6.31 (2001)

• Continuum 20-noded element

• No. of element = 4774

• No. of node = 20275

• Pore pressure element (Coupled consolidation analysis)

• Assumed half mesh (symmetrical)

• Boundary = 62m (10D) x 62m (10D) x 90m (15D)

• Four soil layers: G4a, G4b, G4c and G4d

• Simulation of shield, over-cut, grout and lining elements

• Step by step excavation up to 60m

1.5m

60.5m

5.3m 5.3m

Lining

Shield machine

Over-cut

Grouting

Soil

74m

62m 90m

G4d

G4a

G4b

G4c

After Yong (2004)

RESULTS OF TYPICAL ANALYSIS

• Axial response of piles

0

10

20

30

40

50

60

70

-5000-4000-3000-2000-10000

Axial force (kN)

Dep

th (m

)

Measured (Pile P1)

Measured (Pile P2)Pile P1

Pile P2

Tunnnel springline

Axial force Pile settlement After Yong. (2004)

PILE GROUP DEFORMATION DUE TO TUNNELLING

+18m +6m 0m -6m -18m -27m (+3D) (+1D) (0D) (-1D) (-3D) (-4.5D)

Tunnel-pile relative

position

View in

transverse

direction

View in

longitudinal

direction

Magnified scale - 1500 times After Yong (2004)


Assessment of Risk of Damages due to Tunnelling Induced Ground Movement

• Level of Risk

• Preliminary Assessment – Greenfield

• Second-stage Assessment – Soil Structure interaction based on previous works (charts)

• Detailed Evaluation • Sequence & method of excavation

• Structural continuity – Brick, RC, Steel frame etc.

• Foundation – Spread, Strip, Raft, Pile. Etc.

• Orientation of Buildings • Soil Structure Interaction Analysis

• Previous Movements


Example of Adjacent Building Damage Risk Management Associated Tunnelling in Bangkok Bluel Line MRTA


Guideline on Protection Measures Requirement for Tunnelling nearby existing

structures (after Otogawa, 1983)


STAGED ASSESSMENT • Building Condition Survey:-Check all buildings in influence zone

• No further check if predicted settlement < 10 mm & ground slope <1/500

• Check damage level using the limiting tensile strain approach (Burland et al & Boscardin and Cording)

• Structures placed in Category 3 of damage classification (moderate) or above need further assessment (detailed analyses)

• Establish protective measures requirement

• Monitoring (till 3 months after movement stops)


Observational Method and Instrumentation


0

10

20

30

40

50

60

DE

PTH

BE

LOW

GR

OU

ND

LE

VE

L (m

)

0

10

20

30

40

50

60

20+000 21+000 22+000 23+000 24+000 25+000 26+000 27+000 28+000 29+000 30+000

TUNNELING HORIZON

MADE GROUND

BANGKOK SOFT CLAY

1ST STIFF CLAY

VERY STIFF CLAY

MEDIUM DENSE CLAYEY SAND

DENSE SAND

HARD CLAY

DARK GREY CLAY

MADE GROUND

BANGKOK SOFT CLAY

1ST STIFF CLAY

VERY STIFF CLAY

DENSE SAND

HARD CLAY

0

60

20

40

80

100

0

60

20

40

80

100

THIAM RUAM MITPRACHARAT

BAMPHENSUTTHISAN

RATCHADALAT PHRAO

PHAHONYOTHIN MO CHIT

KAMPHEANG

PHETBANG SUE

SURFACE SETTLEMENT AND SOIL PROFILE IN NORTH CONTRACTS

UR

FAC

E S

ETT

LEM

EN

T (m

m)

NORTH BOUND

SOUTH BOUND

HARD CLAY

DENSE SAND

VERY STIFF CLAY

HUA LAMPONG SAM YAN SILOM LUMPHINI BONKAI SIRIKIT CENTER SUKHUMVIT PETCHABURI RAMA IX

0

10

20

30

40

50

60

0

10

20

30

40

50

60

DE

PTH

BE

LOW

GR

OU

ND

LE

VE

L (m

)

10+050 11+000 12+000 13+000 14+000 15+000 16+000 17+000 18+000 19+000

MADE GROUND

BANGKOK SOFT CLAY

1ST STIFF CLAY

VERY STIFF CLAY

MEDIUM DENSE CLAYEY SAND

HARD CLAY

DARK GREY CLAY

TUNNELING HORIZON

NORTH BOUND

SOUTH BOUND

MADE GROUND

BANGKOK SOFT CLAY

1ST STIFF CLAY

DENSE SAND

VERY STIFF CLAY

HARD CLAY

SURFACE SETTLEMENT AND SOIL PROFILE IN SOUTH CONTRACT

DENSE SAND

0

60

20

40

80

100

0

60

20

40

80

100

SU

RFA

CE

SE

TTLE

ME

NT

(mm

)

NORTH BOUND

SOUTH BOUND

DENSE SAND

HARD CLAY

HARD CLAY


-180.0

-160.0

-140.0

-120.0

-100.0

-80.0

-60.0

-40.0

-20.0

0.0

10.000 12.000 14.000 16.000 18.000 20.000 22.000 24.000 26.000 28.000 30.000Station, Km

Settle

ment,

mm

Side-by-Side TunnelsStacked Tunnels

SURFACE SETTLEMENT

South Contract North Contract

Ground Settlement Array of Section D (Vertical stacked section)

-140

-120

-100

-80

-60

-40

-20

0

-50 -40 -30 -20 -10 0 10 20 30 40 50

Distance from Centre between Two Tunnels(m)

Surf

ace

Settl

emen

t (m

m)

CS-1A

CS-2A1

CS-2A2

CS-2B

CS-3B

CS-3C

CS-4B

CS-4C

CS-4D

NB

SB

Ground Settlement Array of Section D (Parallel section)

-100

-80

-60

-40

-20

0

-50 -40 -30 -20 -10 0 10 20 30 40 50

Distance from Centre between Two Tunnels(m)

Surf

ace

Settl

emen

t (m

m)

CS-5B

CS-5C

CS-5D

CS-5E

CS-5G

CS-5H

NB SB

Section D-1 (Stacked tunnels)

Section D-2 (Side-by-Side tunnels)


0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00

i/R

Z/2R

Single tunnel

Twin Tunnel

Soft to Stiff clay

Rock, Hard Clays,

Sand above

groundwater level

Sand below

groundwater level

0

5

10

15

20

25

30

35

40

0 5 10 15 20

Trough width parameter, i (m)

Dep

th, Z

(m)

Single tunnel

Twin tunnel i = 0.3Z i = 0.4Z i = 0.5Zi = 0.6Z

Width of Settlement Trough


Correlation between Volume Loss and Ratio of Face Pressure to Overburden Pressure

0.0

1.0

2.0

3.0

0.0 0.2 0.4 0.6 0.8 1.0

Gro

und

loss

,VL

(%)

Ratio of EPB face pressure to overburden pressure

Side by side Tunnels

Stacked Tunnels

Ground Loss versus Face Pressure Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

-70

-60

-50

-40

-30

-20

-10

0

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200

Surf

ace

sett

lem

ent (

mm

)

Longitudinal distance to tunnel face (m)

Figure 4.56 Ground movement with tunnel face advancement section AR-26-001

South Bound

North Bound

Approach Move away


-50

-40

-30

-20

-10

0

10

0 180 360 540 720

Surfa

ce S

ettle

men

t, m

m

Elapsed time, Days

Section 28

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

0 180 360 540 720

Sur

face

Set

tlem

ent,

mm

Elapsed time, days

Section 23

Long-term Ground Movements

Bangkok MRTA Blue Line – Settlement of Nearby Buildings

Case Example: London Underground Extension

Compensation Grouting


Thank You

• Principles for Tunnel Design 20th to 21st April 2017– Kuala Lumpur

Disclaimer a) The speakers are presenting their own personal views and are not expressing the view of the Foundation. b) Papers and documents displayed or handed out during the Event are copyrighted. The participants must observe and comply with all applicable law regulations concerning the copyright.

Principles for Tunnel Design

20th to 21st April 2017– Kuala Lumpur

principles for tunnel design 20th to 21st april 2017 kuala ... · numerical methods- plaxis, flac,...

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