A Quantitative Verification of Some A Quantitative Verification of Some Standard Support Patterns in Standard Support Patterns in Japanese Tunneling Design Japanese Tunneling Design

StandardsStandards

20052005

Department of Civil and Structural EngineeringDepartment of Civil and Structural Engineering

Kyushu University, Fukuoka, JapanKyushu University, Fukuoka, Japan

九州大学大学院工学府九州大学大学院工学府

建設システム工学専攻建設システム工学専攻

SONYOK DESH RAJSONYOK DESH RAJ

BackgroundBackground

Tunneling design is still empirical or semi-empirical. Tunneling design is still empirical or semi-empirical.

Reinforcing effect of standard pattern is not clear.Reinforcing effect of standard pattern is not clear.

Quantitative approach for design modification Quantitative approach for design modification

PurposePurpose　

Quantitative verification of supporting effect:Quantitative verification of supporting effect:

(1) Japan Road Association(1) Japan Road Association

(2) Japan Highway Public Corporation (2) Japan Highway Public Corporation

(3) Japanese National Railways.(3) Japanese National Railways.

Background and PurposeBackground and PurposeBackground and PurposeBackground and Purpose

Theoretical basis of this studyTheoretical basis of this study Quantitative analysis of the standard support Quantitative analysis of the standard support

patterns patterns Study parameters and assumptionsStudy parameters and assumptionsResultsResults

ConclusionsConclusions Future studyFuture study

ContentsContentsContentsContents

Elastic-plastic analysis Elastic-plastic analysis

(Mohr-Coulomb theory)(Mohr-Coulomb theory)

Strain soften model, Strain soften model, dilationdilation

Interaction behavior of rock Interaction behavior of rock mass and rock bolt:mass and rock bolt:

(Coupling and (Coupling and

decoupling decoupling

behavior)behavior)

Theoretical basis of the studyTheoretical basis of the studyTheoretical basis of the studyTheoretical basis of the study

Rera fRO

ω

o

symmetric

Po

Lz

LT

LT

ρ L1

r

Plastic flow zoneSoften zoneElastic zone

P m a xt u n n e lo p e n i n g

g r o u n d

r o c k b o l t

d i s t r i b u t i o n o f a x i a l f o r c e

Neutral point

0 500 1000 1500 2000 2500 3000

I L

I S

I N

II N

III N

DII

DI

CII

CI

B

DII

DI

CII

CI

B

Rock m

ass c

lass

De f o rma t io n mo du lu s Em (GPa)

J apan e s e Nat io n a l Ra ilways

J apan Ro ad As s o c ia t io n

J apanHighway Public Co rpo ra t io n

Ranges of deformation modulusRanges of deformation modulusRanges of deformation modulusRanges of deformation modulus

Japan Road Association

Japan Highway P. Corp.

Japanese National Railways

Deformation modulus (MPa)

Roc

k m

ass

clas

ses

0 300020001000

β= 0 ～ 1.0

Study parameters and case arrangementsStudy parameters and case arrangementsStudy parameters and case arrangementsStudy parameters and case arrangements

Em = deformation modulus of rock mass

σc = axial strength

Srp = Competency factor (=σc/γH)

γ = density of rock

H = overburden depth

β = rock bolt density parameter　 (1 = 50×50 cm)

Em=200σc

Srp = 0.1 ～2.0

2 /b a z tr r L Lβ π λ=

ra=tunnel radius, rb=radius of rock bolt , λ is friction coefficient Lz and Lt are rock bolt spacing.

Study Parameters of Japan Road AssociationStudy Parameters of Japan Road AssociationStudy Parameters of Japan Road AssociationStudy Parameters of Japan Road Association

(a) Tunnel radius = 6.25 m ( 4.25 ~ 6.25 m)

JA1-Pt7>0.28>0.236<1.01.24DIIDII

JA1-Pt60.2111.24DI-b

JA1-Pt50.210.23611.23DI-aDI

JA1-Pt40.150.161.21.53CII-b

JA1-Pt30.10.161.21.53CII ー aCII

JA1-Pt20.10.1281.51.53CICI

JA1-Pt10.050.09421.53BB

Support pattern no

t'c

(m)βLz (m)Lt (m)L (m)

Support class

Rock class

Study Parameters of Japan Highway P. Corp.Study Parameters of Japan Highway P. Corp.Study Parameters of Japan Highway P. Corp.Study Parameters of Japan Highway P. Corp.

Tunnel radius = 5.1 m

JH-Pt7>0.28>0.24<1.01.24DIIDII

JH-Pt60.210.2411.24DI-b

JH-Pt50.210.2411.23DI-aDI

JH-Pt40.150.21.21.23CII-b

JH-Pt30.10.161.21.53CIIー aCII

JH-Pt20.10.1281.51.53CICI

JH-Pt10.050.09421.53B-aB

Support pattern no

t'c (m)βLz

(m)Lt (m)L (m)

Support class

Rock class

Study Parameters of Japan National RailwaysStudy Parameters of Japan National RailwaysStudy Parameters of Japan National RailwaysStudy Parameters of Japan National Railways

Support pattern no

t'c (m)βLz (m)Lt (m)L (m)Support class

JR2-Pt60.280.16311.93IL

JR2-Pt50.250.28111.14IS

JR2-Pt40.250.28111.13IS

JR2-Pt30.210.19311.63IN

JR2-Pt20.10.0891.52.33IIN

JR2-Pt10.10.0681.532IIIN

JR1-Pt60.280.13412.33IL

JR1-Pt50.250.25811.24IS

JR1-Pt40.250.25811.23IS

JR1-Pt30.210.16311.93IN

JR1-Pt20.10.0681.533IIN

JR1-Pt10.10.0521.53.92IIIN

JA1-Pt1: t'c = 0.05 m and L=3.0 m

JA1-Pt2: t'c = 0.1 m and L=3.0 m

0

0.05

0.1

0.15

0.2

0.25

0 0.2 0.4 0.6 0.8 1

De s n s it y o f ro c k bo lt βStr

ain (U ra/r a

)

Srp=0.1

Srp=0.1~1.2

0

0.05

0.1

0.15

0.2

0.25

0 0.2 0.4 0.6 0.8 1

De s n s it y o f ro c k bo lt ( )β

Str

ain (U ra

/r a

)

Srp=0.1

Srp=0.1~1.2

Influence of shotcrete thicknessInfluence of shotcrete thicknessInfluence of shotcrete thicknessInfluence of shotcrete thickness

JA1-Pt6: rra a =6.25 m,=6.25 m,

t't'cc = 0.21 m = 0.21 m and

L=4.0 mL=4.0 m

JA1-Pt5: rraa =6.25 m =6.25 m, t't'cc = 0.21= 0.21 mm and

L=3.0 mL=3.0 m

Em=0~600 MPa

Influence of Rock bolt lengthInfluence of Rock bolt lengthInfluence of Rock bolt lengthInfluence of Rock bolt length

0

0.02

0.04

0.06

0.08

0.1

0 0.2 0.4 0.6 0.8 1

De n s it y o f ro c k bo lt β

Str

ain

Ura/r

a

Srp=0.1

Srp=0.1~1.2

0

0.02

0.04

0.06

0.08

0.1

0 0.2 0.4 0.6 0.8 1

De n s it y o f ro c k bo lt βStr

ain

Ura/r

a

0.240.24Srp=0.1

Srp=0.1~1.2

0

50

100

150

200

250

300

350

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 .1 1 .2

Compe t e nc y fa c t o r (Srp )

Dis

plac

emen

t (c

m)

Stan da rd Suppo rt (J A1 - Pt7)

No s uppo rt

05

101520253035404550

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 .1 1 .2

Compe t e nc y fa c to r (Srp)

Dis

palc

emen

t (c

m) Standa rd Suppo rt (J A1 - Pt7)

Sh o rt c re t e o n ly

Comparison of tunnel wall displacementComparison of tunnel wall displacementComparison of tunnel wall displacementComparison of tunnel wall displacement

Displacement Displacement restrained by restrained by rock boltrock bolt

JH-Pt5: rraa =5.1 m =5.1 m,

t't'cc = 0.21= 0.21 mm and

L=3.0 mL=3.0 m

JH-Pt6: rraa =5.1 m =5.1 m,

t't'cc = 0.21= 0.21 mm and

L=4.0 mL=4.0 m

Influence of Rock bolt length Influence of Rock bolt length Influence of Rock bolt length Influence of Rock bolt length

0

0.010.02

0.03

0.04

0.050.06

0.07

0.08

0 0.2 0.4 0.6 0.8 1

De ns it y o f roc k bo lt β

Str

ain

(Ura/r

a)

00.01

0.020.030.04

0.050.06

0.070.08

0 0.2 0.4 0.6 0.8 1

De ns ity o f ro c k bo lt β

Str

ain

(U ra/r

a)

Srp=0.2

Srp=0.1

Srp=0.1

Srp=0.2

Srp=0.1~1.2

Srp=0.1~1.2

Em

(MPa)t'c (m)

Length of rock bolt

2 m 3 m 4 m 6 m

600 ~ 30000.05

JA1-Pt1 (B)

600 ~ 1200 JH-Pt1 (B)

600 ~ 3000

0.1

JA2-Pt1 (B)

300 ~ 1200 80 ~ 1200

JR1-Pt1 (IIIN) JR2-Pt1 (IIIN)

JA1-Pt2 (CI)JA1-Pt3 (CII)

80 ~ 600

JH-Pt2 (CI)JH-Pt3 (CII)JR1-Pt2 (IIN)JR2-Pt2 (IIN)

300 ~ 1200

0.15

JA2-Pt2 (CI)

80 ~ 1200 JA1-Pt4 (CII)

80 ~ 600 JH-Pt4 (CII)

Comparison of Different Standard SupportsComparison of Different Standard SupportsComparison of Different Standard SupportsComparison of Different Standard Supports

20 ~ 600

0.21

JA1-Pt5 (DI) JA1-Pt6 (DI)

80 ~ 300 JH-Pt5 (DI)

80 ~ 1200 JA2-Pt3 (CII)

80 ~ 300 JR1-Pt3 (IN)JR2-Pt3 (IN)

JH-Pt6 (DI)

80 ~ 300 0.25 JR1-Pt4 (IS)JR2-Pt4 (IS)

JR1-Pt5 (IS)JR2-Pt5 (IS)

0~ 6000.28

JA2-Pt4 (DI)

0~ 300 JR1-Pt6 (IL)JR2-Pt6 (IL)

JA1-Pt7 (DII)JH-Pt7 (DII)

0~ 600 0.38 JA2-Pt5 (DII)

Continued…..

Comparison of supporting effectsComparison of supporting effectsComparison of supporting effectsComparison of supporting effects

JA1-Pt2 & JH-Pt2, β=0.13

JA1-Pt3 & JH-Pt3, β=0.16

JR1-Pt2, β=0.07

JR2-Pt2, β=0.09

Srp=1.2 Srp=0.8Srp=0.6

Srp=0.4

Comparison of supporting effectsComparison of supporting effectsComparison of supporting effectsComparison of supporting effects

JA1-Pt5 &JH-Pt5, β=0.24

JR1-Pt3, β=0.16

JR2-Pt3, β=0.19

Srp=0.6

Srp=0.4

Srp=0.8Srp=1.2

Shortcrete plays an important effect in the Shortcrete plays an important effect in the reinforcing system.reinforcing system.

− Improvement of rock bolting effect (Improvement of rock bolting effect (Srp<0.4Srp<0.4) )

− No significant improvement (No significant improvement (Srp>0.8)Srp>0.8) Rock bolt length: Rock bolt length:

− up to 6 m, increases the rock bolting effect in up to 6 m, increases the rock bolting effect in weak rock masses when rweak rock masses when raa=6.25~7 m.=6.25~7 m.

− no difference is seen when the rock bolt is no difference is seen when the rock bolt is longer than 3 m for medium size tunnel when longer than 3 m for medium size tunnel when rraa=5.1 m=5.1 m. .

Conclusion (1)Conclusion (1)Conclusion (1)Conclusion (1)

Supporting patterns of JH is almost similar to that Supporting patterns of JH is almost similar to that of JRA. of JRA.

In a good ground condition, rock bolt density of In a good ground condition, rock bolt density of JR is smaller than that of JH/JRA. However, there JR is smaller than that of JH/JRA. However, there is no significant difference of the rock bolting is no significant difference of the rock bolting effect.effect.

In a weak ground condition, rock bolt density of In a weak ground condition, rock bolt density of JR is larger than that of JH/JRA. Reinforcing JR is larger than that of JH/JRA. Reinforcing effect of the pattern of JR is a little better than effect of the pattern of JR is a little better than that of JH.that of JH.

Conclusion (2)Conclusion (2)Conclusion (2)Conclusion (2)

• Comprehensive verification with measured in-situ data

• Consider gravity effect and try to include influence of in-situ stress ratio.

• Study on shallow depth tunnel

Future studyFuture studyFuture studyFuture study

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