Structural Consequences of Tunnel Waterproofing · Structural Consequences of Tunnel Waterproofing Tarcísio B. Celestino Themag Engenharia University of São Paulo - São Carlos

Structural Consequences of

Tunnel Waterproofing

Tarcísio B. CelestinoThemag Engenharia

University of São Paulo - São Carlos

1 Dec 2015

1. Inflow estimates and back analyses

2. Types of permanent lining

3. Consequences of potential clogging of geotextiles

4. PVC membrane – concrete interaction

5. Spray-on membrane – concrete interaction: tests and FEM

analysis

6. Creep behavior of PVC membranes subjected to

compression

7. Conclusions

2

1 – Inflow estimates and back

analyses

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pro

fund

ida

de

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Inflow back analysis

Zuquim Tunnels, São Paulo Metro

4

0

5

10

15

20

25

1,00E-12 1,00E-11 1,00E-10 1,00E-09 1,00E-08

Permeability lining (m/sec)

São Paulo Leste

SarniaBattery

Hudson

PRR Hudson

River

Blackwall (2)

Clyde

Greenwich

Toronto

subway

PRR East River

Blackwall (1)Rotherwhite

Severn

Maria Maluf A-IMaria Maluf I-ASão Paulo Oeste

Sé - São Bento

Santa CeciliaLuminarias

EstacionamentoZuquim - W

Zuquim - E

Shotcrete

Bolted cast iron with concrete

Bolted cast iron

Bolted concrete

Sprayed concrete lining permeability

(Celestino, 2001)

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2 – Types of permanent lining

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Double shell lining (DSL)• Sacrificial primary lining for temporary loads

• Secondary lining for total permanent loads

• No monolithic behavior

Single shell lining (SSL)• Primary lining for temporary loads

• Secondary lining + primary lining for permanent loads

• Monolithic behavior

Composite shell lining (CSL)• Primary lining for temporary loads

• Spray-on waterproofing membrane• Secondary lining + primary lining for permanent loads

• Monolithic behavior

Options of Sprayed Concrete Lined Tunnels (SCL)

(Thomas & Pickett, 2011)

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Double shell and composite shell linings

(Thomas & Pickett, 2011)

DSL CSL

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Single shell lining

• No waterproofing membrane

• Structural role of both primary and secondary layers

• Infiltrations acceptable (consider evaporation)

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Evaporation in tunnels

(AFTES, 1989)

• Q – flow rate (l/h)

• F – water vapor saturation pressure (mm Hg)

• f – ambiente water vapor pressure (mm Hg)

• s – area (m2)

• U – air velocity (m/s)

Q = 0,01785s(F – f)(1 + 0,0862U)

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ITA WG 12 “Shotcrete for Rock Support”, 2004

“The contributions from different countries illustrate well the

widely different views on rock support design. This becomes

especially evident when comparing sometimes the over-

conservative cast in place concrete linings with what evidently

is satisfactory support under similar conditions using shotcrete.

There are many examples of thickness reduction from one

meter down to 10 to 15 cm of shotcrete”

K. Garshol

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Composite Shell Lining

• Spray-on membranes

• Monolithic behavior (ground mass – concrete – membrane

interaction)

• Different assumptions of sacrifice layer

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Primary Lining (Shotcrete)

Secondary Lining (Shotcrete)

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Rotation capacity of plastic hinges

(adapted from NBR 6118:2003),

where x is the depth of the neutral

line and d is the cantilever of

reinforcement.

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Single-shell lining – Germany (single track tunnels, Pöttler & Klapperich, 2001)

C- claystone; M – marl; S - sandstone

Year 1981-83 1982 1984-87 1987-89

Ground mass S/M S/M M C

Pressure (bar) 0.5 0.5 0.5 0.6

Thickness (cm) 37 25 39 40

Year 1987-89 1989-90 1989-92 1981 1991

Ground mass C M M M C/M

Pressure (bar) 0.6 0 1.2 0.5 0

Thickness (cm) 25 40 55 30 35

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Single-shell lining - São Paulo Metro

Single track tunnels (~ 6m diameter)

• Year: 1981 - 1992

• Ground mass: stiff clays and water bearing sands

• Pressure: 0.5 to 2.0 bar

• Total thickness (sprayed concrete): 20 to 25 cm

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Comparison of total lining thickness

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São Paulo Metro North Extension (1989)

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Santiago Metro, Estación Cerro Blanco

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Rio de Janeiro Metro - Arcoverde Station

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Stockholm Metro

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3 – Consequences of potential

cccclogging of geotextiles

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Water pressure on tunnel lining – potential

clogging of geotextiles

(Shin et al., 2005)

• Time-dependent problem

• Non-woven geotextiles loose drainage capacity (clogging

and compression)

• Role of permanent lining

• Limited (or no) long-term instrumentation

• Coupled numerical analyses

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Loss of geotextile drainage capacity

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Pressure as a function of geotextile drainage

capacity

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Secondary lining failure – Seoul Metro

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4 – PVC membrane – concrete

interaction

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Experimental Program

Ribeiro & Bueno, 2005

Uniaxial compression concrete with PVC membrane and PVC +

geotextile

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Concrete and membrane perpendicular flat

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Concrete and membrane perpendicular flat

additional displacement

sigma x d5-d3

0

5

10

15

20

25

30

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-0.1 0 0.1 0.2 0.3 0.4 0.5

d (mm)

s (

MP

a)

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Perpendicular undulated membrane CP7

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Perpendicular membrane with voids

CP 17

CP17

0

2

4

6

8

10

12

0 0.2 0.4 0.6 0.8 1 1.2 1.4

d (mm)

s (

MP

a)

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Relative deformability

1 a 3 4 a 6 7 a 9 16 a 18

E rel (%) 100 32,5 28,1 24.0

CV (%) 0.01 40.12 42.02 46.10

1 a 3 4 a 6 7 a 9 16 a 18

E rel (%) 100 17.3 3.7 4.3

CV (%) 0.01 72.00 33.16 65.41

Membrane

Membrane + geotextile

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Normal stiffness of interfaces

Specimens Kn (MPa/mm)

4 – 6 M 38,5

7 – 9 M 31,3

16-18 M 25,3

4 – 6 M+G 16,7

7 – 9 M+G 3,1

16-18 M 3,6

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0

Direct shear

Cisalhamento de interface

0

10

20

30

40

50

60

0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0 11,0

deslocamento (mm)

Ten

são

(kP

a)

25 kPa

50 kPa

75 kPa

t = 5 + stan34,3 (kPa)35

5 – Spray-on membrane – concrete

interaction: tests and FEM analysis

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Sprayed concrete linign interaction with

sprayed-on membrane(Nakashima et al., 2015; Cambridge and Ruhr Universities)

• Full scale specimens of sprayed concrete isolated by

waterproofing membrane

• 4-point bending tests to simulate high bending moments

• Excentric compression tests (high hoop stresses)

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4-point bending test

(large bending moments)

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Excentric compression test

(high hoop stresses)

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4-point bending test

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Excentric compression test

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4-point bending test

typical results

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Analysis of progressive water level rising

Density

ρm=2100 kg/m³ρs=2400 kg/m³

Cohesion

cm=200 kPa

Friction angle

fm=25º

Dilatancy

φm=22,5º

Elasticity

Em= 3,16 GPa,νm=0,3Es= 21 GPa,νs=0,3

Parameter Value Normal stiffness 16,0 MPa/mm Shear stiffness 3,6 MPa/mm

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Results of strucutural interaction

Stage of secundary lining

Stage WL - 1Stage WL - 2Stage WL - 3Stage WL - 4

Relative displacementsDisplacements – secondary liningStage WL-4: Internal forces in the liningStage 4: PlasticityNormal force – secondary lining Bending moment – secondary lining

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6 – Creep behavior of PVC

membranes subjected to

compression

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N.A 1

N.A 2

Buoyancy in shaft lined with concrete and

sheet membrane

U

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R = U - P

R = Reaction of primary sprayed concrete

P

R

U

Reaction of primary on secondary lining

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t

se MPa 6

s 6MPa

s 6MPa

Long-term interaction

Primary lining – membrane – secondary lining

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Punching testASTM D 4833

F 8mm tip

Non-representative condition

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Creep test under localized load

F F

Flat tip Spherical tip

Constant force

Time-dependent displacement

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Test set up

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Typical result

s = 6,7 MPa (shade)

Sphere diameter= 1.22cm

Deformação Lenta

0,00

0,50

1,00

1,50

2,00

2,50

0 500 1000 1500 2000 2500

Tempo (s)

Deslo

cam

en

to (

mm

)

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7 - Conclusions

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• Inflow criteria: operation conditions and durability

• Adavantages of umbrella-type systems: lower structural

demand; pre-grouting eventually needed

• Use of sheet membranes does not allow primary –

secondary lining interaction

• Spray-on membranes allow primary – secondary lining

interaction

• Long term compression of sheet membranes on sprayed

concrete surfaces not recommended

• Importance of the role of final lining

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Thank you!!!

[email protected]

[email protected]