Unexpected performance and cost factors for hard rock TBM. Analyses of specific cases with the thrust- penetration gradient

Dr. M. WehH. Wannenmacher

WTC 2014Marti Holding AGwww.martiag.ch

Unexpected performance and cost factors for hard rock TBM. Analyses of specific cases with the thrust- penetration gradient

• Thrust-Penetration Gradient

• Influence of Tunnel diameter

• Influence of overburden

• Influence of joint alteration

Thrust-Penetrati

on Gradient

Influence of Tunnel diameter

Influence of

overburden

Influence of joint

alteration




TBM-specific influencing factors • Type, spacing and wear rate of cutters.• TBM-diameter.• Thrust per cutter.

Intact Rock/ Rock Mass influencing factors:• Intact UCS.• Grade and orientation of

anisotropy of rock mass.• Joint conditions, joint orientation towards the tunnel alignment and spacing of joints.• Magnitude and orientation

of stress conditions and effects of stress

redistribution on rock mass behaviour.

Thrust-Penetrati

on Gradient


Influence of

overburden

Influence of joint

alteration

0

5

10

15

20

25

30

35

40

0 50 100 150 200

penetration(mm/rev)

thrust/cutter (kN)

Islisbergtunnel, Silt/Sandstone: 30MPaGorgier, Marlestone: 28MPaGorgier, Limestone: 120MPaBure: Marlestone: 20MPaBure, Limestone: 130MPaKatzenberg, Limestone: 100MPaKatzenberg: Marlestone,

Low rock strength: High gradient

High rock strength: Low gradient




Scale dependency of tunnel radii on the thrust penetration gradient

Small tunnel diameter: Low gradientBig tunnel diameter: High gradientThrust-

Penetration Gradient


Influence of overburden

Influence of joint

alteration0 50 100 150 200 250

-0.1

2.77555756156289E-17

0.1

0.2

0.3

0.4

0.5

0.6

TBM projects with overburden < 1000mr > 5500mmPower (r > 5500mm)3500 < r < 5500mm Power (3500 < r < 5500mm ) 2500 < r < 3500mmPower ( 2500 < r < 3500mm)r < 2500m

uniaxial compressive strength (MPa)

thru

st p

enet

ratio

n gr

adie

nt (m

m/r

ev/

kN/c

utter

)

Tunnelradius:

Factor 2 in diameter is more than factor 2 in gradient




Influence of stress on the thrust-penetration gradient

Relation overburden/UCS < 4: Low thrust-penetration gradientRelation overburden/UCS > 7: High thrust-penetration gradient (+60%)Thrust-

Penetration Gradient

Influence of Tunnel

diameter

Influence of

overburden

Influence of joint

alteration

50 100 150 200 250 3000.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

f(x) = 1.29211351269115 x -̂0.495221562010313R² = 0.506918659372934

f(x) = NaN x^NaNR² = NaN TBM radius = 4715mm

overburden/UCS < 4, LöschbergPower (overburden/UCS < 4, Löschberg)4 < overburden/UCS < 7; Lötschbergoverburden/UCS > 7: Lötschberg

uniaxial compressive strength (MPa)

thru

st p

enet

ratio

n gr

adie

nt (m

m/r

ev/

kN/c

utter

)




Influence of stress on the thrust-penetration gradient

Relation overburden/UCS small: Narrow distribution of gradientRelation overburden/UCS high: Wide distribution of gradient

Thrust-Penetration

Gradient

Influence of Tunnel

diameter

Influence of

overburden

Influence of joint

alteration

0%5%

10%15%20%25%30%35%

freq

uenc

y(%

)

gradient (mm/rev/kN/cutter)

0%5%

10%15%20%25%30%35%

freq

uenc

y(%

)


0%

5%

10%

15%

20%

25%

30%

35%

freq

uenc

y(%

)


0%5%

10%15%20%25%30%35%

freq

uenc

y(%

)


Fine grained migmatitic gneiss (270MPa,overburden/UCS = 6.3)

Coarse grained granite (150MPa,overburden/UCS = 9.8)

migmatitic gneiss (112MPa,overburden/UCS = 5.55)

metamorphic slates (77MPa,overburden/UCS = 5.03)

0.00

5

0.01

5

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0.1

unstable faceunstable face




Influence of joint alteration on the thrust-penetration gradient

Thrust-Penetration

Gradient

Influence of Tunnel

diameter


Influence of joint

alteration 0 2 4 6 8 10 12 140.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

TBM radius = 4715-4725mm

Löschberg Nant de Drance

overburden/UCS

thru

st p

enet

ratio

n gr

adie

nt (m

m/r

ev/

kN/c

utter

)

Unexpected low gradient expierenced in the access tunnel of Nant de Drance P.S.S. .




Influence of joint alteration (Nant de Drance P.S.S.)

Thrust-Penetration

Gradient

Influence of Tunnel

diameter


Influence of joint

alteration

Healing of joints (growth of chlorite and quartz) due to hydrothermal activity increases strength of rock mass decreases the thrust-penetration gradient significantly .

Engineering

Unexpected performance and cost factors for hard rock TBM. Analyses of specific cases with the thrust- penetration gradient