AKADEMIA GÓRNICZO-HUTNICZA

IM. STANISŁAWA STASZICA

W KRAKOWIE

Wydział Górnictwa i Geoinżynierii

Budownictwo

Rok III, Grupa 5

B

UDOWNICTWO PODZIEMNE

Wykonał:

Bartłomiej Urbanek

Kraków 2014

2

Contents

1.

Parameters ............................................................................................................................ 3

2.

Rock Quality Designation Index (RQD) .................................................................................. 4

3.

Rock Mass Rating .................................................................................................................. 4

4.

Parameters ............................................................................................................................ 5

4.1.

In-situ deformation modulus ................................................................................ 5

4.2.

Strength parameters.................................................................................................... 6

5.

Rock Tunnelling Quality Index Q ........................................................................................... 6

6.

Equivalent dimension D

e

....................................................................................................... 7

7.

Tunnel support (in accordance with the Q Classification) .................................................... 8

8.

Parameters ............................................................................................................................ 9

8.1.

Deformation modulus ........................................................................................... 9

8.2.

Roof pressure............................................................................................................... 9

9.

Q – RMR Correlations ............................................................................................................ 9

10.

Conclusion ........................................................................................................................... 10

3

1.

P

ARAMETERS

Lp.

Parametr

Wartość lub opis

1.

Shape, size and purpose of tunnel

(cavern)

Chamber for the underground parking In the

shape of rectangle with vaulted ceiling, 40 m

width, 15 m height

2.

Average depth, m

50

3.

General rock mass characteristics in

the vicinity of tunnel (cavern)

Compact and block rock mass

4.

Average compressive strength of

surrounding rocks, MPa

120

5.

Average tensile strength of

surrounding rocks, MPa

13

6.

RQD, % diameter of core 55 mm

As in picture below

Jak na rysunku

7.

Number and average sparing of joint

sets

Two discontinuity sets, average spacing is about

1,0 m

8.

Characteristic of the discontinuities

Layers in contact, impermeable, natural fill

gouge

9.

Groundwater conditions

Drippings

10.

Discontinuity strike and dip

orientation

Strike perpendicular to chamber’s axis, driver in

the opposite direction (angle 45

o

)

11.

Excavation method

Blasting

MW

4

2.

R

OCK

Q

UALITY

D

ESIGNATION

I

NDEX

(RQD)

∑

- Total length of core run

- Length of core pieces length

3.

R

OCK

M

ASS

R

ATING

Parameter

Value

Rating

Comment

1

Uniaxial compressive

strength

120 MPa

12,6

Determined by linear

interpolation

2

RQD

87 %

19.4

Determined by linear

interpolation

3

Spacing of discontinuities

1,0 m

15.11

Determined by linear

interpolation

4

D

is

co

n

ti

n

u

it

y

ch

ar

ac

ter

is

ti

cs

Discontinuity length

3-10 m

2

I do not have any information

about that parameter so I

chose medium value

Separation

None

6

I have information that layers

are in contact so I choose the

highest score

Roughness

Rough

5

Because of impermeable

5

filling and contacted layers I

choose high roughness

Infilling

Hard filling

<5mm

4

It is a natural filling- hard rock

with high strength.

Impermeable - so smaller

than 5 mm

Weathering

Unweathered

6

Because of impermeable

filling and contacted layers

there is no possibility to

provide weather

5

Ground water

Dripping

4

There is small amount of

water in ground so rate is not

too big

6 Strike and dip orientations

Strike

perpendicular to

chamber’s axis,

driver in the

opposite

direction (angle

45

o

)

-10

Chamber with unfavourable

strike and dip orientation

RMR

64,11

Rock class: II – Good Rock (61-80)

4.

P

ARAMETERS

4.1.

In-situ deformation modulus

Bieniawski (1978) and Serafim & Pereira (1983)

for

Hoek and Brown (1997)

√

( )

√

( )

6

Verman (1993)

( )

( )

4.2.

Strength parameters

Hoek (1994):

√

√

Aydan & Kawamoto (2000)

( )

( )

Kalamaras & Bieniawski (1995)

I received different values of the parameters

and

and I decided to choose the middle

value of each parameters:

(Hoek and Brown)

(Kalamaras & Bieniawski)

5.

R

OCK

T

UNNELLING

Q

UALITY

I

NDEX

Q

Parameter

Value

Comment

B

lo

ck

s

iz

e

1

the Rock Quality

Designation

90

Good RQD

(between 75 and 90%)

2

the joint set number

4

Two joint sets and there was no

information about randomness

In

ter

-

b

lo

ck

sh

ea

r

st

ren

g

th

3

the joint roughness number

4

Layers in contact, two discontinuity sets

7

4

the joint alteration number

0,75

The only information which I have is that it

is impermeable and have natural fill

gouge, so I chose “Tightly healed, hard,

non-softening, impermeable filling”

A

ct

iv

e

st

res

s

5

the joint water reduction

factor

1,0

There are impermeable layers, so it is

counted to dry excavation

6

the stress reduction factor

2,5

Single shear zone in competent rock (clay

free). Depth of excavation > 50m (50m).

Rock class: Very Good (40-100)

6.

E

QUIVALENT DIMENSION

D

E

Excavation span

Excavation height

Excavation Support Ratio (I classified underground hall to “sports and public
facilities” (excavation category – D)

8

7.

T

UNNEL SUPPORT

(

IN ACCORDANCE WITH THE

Q

C

LASSIFICATION

)

On the basis of the graph results:

Reinforcement category for roof:

Systematic bolting (3)

Bolt spacing in unshotcreted area:

Bolting length:

Reinforcement category for walls: Spot bolting (2)

Bolt spacing in unshotcreted area:

Bolting length:

Crown

Walls

9

Length of bolts:

8.

P

ARAMETERS

8.1.

Deformation modulus

Barton (2002)

√

√

for 〈 〉,

〈 〉

Grimstad and Barton (1993)

8.2.

Roof pressure

√

√

√

√

9.

Q

–

RMR

C

ORRELATIONS

10

Correlation

Source of case

studies and

reference

Result

RMR=

Differential between

correlation and result from

classification table

New Zealand [55]

65,70

1,59

Diverse Origin [25]

78,84

14,73

Spain [56]

76,22

12,11

South Africa [57]

80,16

16,05

Spain [58]

8,31

-55,80

Spain [59]

82,45

18,34

Canada [60]

71,17

7,06

Canada [27]

71,68

7,57

Canada [52]

77,71

13,60

Supposed location: New Zealand

10.

C

ONCLUSION

We should use the two systems to analyse and to compare the rock mass. In this project I
used the RMR system and Q classification. Both of them are most widely used for the rock
mass classifications. They include geological, geometric and design/engineering parameters to
obtain a value of the rock mass quality.

The results that I have achieved are different. According to RMR, the system rock is good
(RMR=61,11). However, according to Q classification, the system rock is excellent (Q=48).

In my opinion, the difference is caused by the lack of information about the few parameters
(e.g. discontinuity length) and an estimation method.

To conclude, I am able to propose the two ways of a support construction. The first one,
based on the RMR classification involves strengthening the construction by locally bolt in
crown (3 m long), spaced 2,5 m with occasional wire mesh and 50 mm shotcrete in crown
(where required).

The second one, based on Q classification involves strengthening the construction by bolts in
crown (10 m long).

Finally, I have received a various value of the deformation modulus. These parameters are
place a higher worth in Q classification.