Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

I

Alfred Zettler

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

Name: Alfred Zettler

Email: a.zettler@zconsult.at

Lessons (suggestion):

10.11.2015 3 pm HS 4

24.11.2015 3 pm HS 4

15.12.2015 3 pm HS 4

12.01.2016 3 pm HS 4

26.01.2016 3 pm HS 4

Written exam:

26.01.2016 5 pm HS 4

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

You learned a lot about techniques, materials, calculation methods, ect. in engineering design.

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

What makes underground excavation design different to other fields of

engineering design?

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

Examples:

� Reinforced concrete

� Steel constructions

� Wood constructions

� Compound materials

(steel and concrete, or wood and steel, ect.)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

Rock mechanics:

The material is not determined by the designer!

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Differences to other fields of engineering?

The main difference to other engineering disciplines is that in rock mechanics the material is pre-determined, e. g.:

Steel, concrete, wood, compound material.

The material is determined.

It is possible to choose material with different characteristics.

Tests are easy to perform and to determine.

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Is it possible to influence the rock

mass around an underground opening?

There are chances to influence the rock mass behaviour around an underground opening:

Shape, Orientation,

Support Measurements

To figure out the best shape and the best orientation is the most successful way to influence the rock mass behaviour around an underground opening.

The target of the lesson is to learn about the influence of the shape, the orientation and support measurements on rock.

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Discontinuities

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Labor Tests

Uniaxial Compressive Test

Speci

fic

Explo

sive

Consu

mption k

g/m

³

(from: Thuro & Plinninger, 2007))

Uniaxial Compressive Strength MPa

Speci

fic

Explo

sive

Consu

mption k

g/m

³

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Specific Explosive

Consumption [kg/m³] =

= 0,393 + 0,116 UCS [MPa]]

(from: Thuro & Plinninger, 2007))

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Drilli

ng V

elo

city

m

/min

Uniaxial Compressive Strength MPa

(from: Thuro & Plinninger, Geologisch-geotechnische Grundlagen der Gebirgslösung im Fels 2006)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Drilling Velocity [m/min] =

= 5,42 - 0,7 ln UCS [MPa]

(from: Thuro & Plinninger, 2007))

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Drill

Bit L

ifetim

e m

/bit

Cerchar Abrasiveness Index (CAI)(from: Plinninger, 2009, Figure 9, Page 44)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Drill Bit Lifetime [m/bit] =

= 3066,3 EXP(-0,452 CAI [-])

(from: Plinninger, 2009, Figure 9, Page 44)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

How do we influence the rock mass?

Often there is no chance to optimize the orientation, then it is necessary to optimise shape and support measurements.

In a few cases we finally have to accept the rock mass and the rock mass behaviour and we have to deal with it.

Fore example: Rock burts

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Rockburst in an underground mine

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Rockburst at Gothard base tunnel

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

How do we influence the rock mass?

But often we do not use the possibilities to influence the rock mass behaviour.

We make a poor blasting.

Often a gentle treatment of the rock will help us to minimize rock failures and therefore minimise the costs for tunnelling.

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Poor blasting

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Good blasting

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Achraintunnel road header

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

How do we influence the rock mass?

In the following you see different roof failures.

Most of them are wedge failures.

That means that wedges are falling out due to gravity.

In many cases we must use systematic support measurements to avoid rock mass failure for example wedge failure in the tunnel roof.

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

A wedge failure in the roof of the top heading of the Rio Grande tailrace tunnel (Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

A 6m wide heading driven ahead of the tunnel to permit pre-reinforcement of potential unstable wedges in the roof (Photo: Hoek Rock Engineering, course notes)

Tunnel shape

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Ambergtunnel

Wedge failure in the roof of the top heading

Wedge forms the tunnel shape

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Ambergtunnel

Wedge failure in the roof of the top heading

Wedge forms the tunnel shape

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Ambergtunnel

Wedge failure in the roof of the top heading

Wedge forms the tunnel shape

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

How do we influence the rock mass?

Orientation (if it is not determined)

Shape of the tunnel

Excavation Stages

Support measurements

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

(Foto: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

A view of the 25 m span Rio Grande power cavern during excavation of the lower bench (Photo: Hoek Rock Engineering, course notes)

Pick- up

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

Partially completed 20 m span, 42.5 m height underground powerhouse cavern of the NathpaJhakri Hydroelectric Project in HimachelPradesh, India. The cavern is approximately 300m below the surface.(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

How do we influence the rock mass?

Support measurements

shotcrete

rock bolts

wire mesh

steel sets

forepoles

ect.

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Support MeasurementsTunneling Class6/4,43 (top heading)5/2,42 (bench)1/1 (invert)

steel set 70/20/30

shotcrete ds=20cm

1 layer wire meshAQ50 rock side

1 pice rock bolt SN-Type 250kN l=3m

shotcrete ds=15cm

7,5 pices rock boltSN-Typ 250kN l=6m

1 layer wire meshAQ50 rock side

1 layer wire meshAQ50 rock side

7,5 pices rock boltSN-Typ 250kN l=6m

11 pices forepoles not cement groutet l=3m e=35cm

tunnel faceshotcrete ds=5cm

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Achraintunnel shotcrete escape tunnel

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Tauerntunnel Support measurements

Underground Excavation Design

Rockbolt SN-type (Store-Norfors)

first used in Store-Norfors cole mine

Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design

Wire mesh

Part 1 Tunnel Design Introduction Alfred Zettler

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Tunnel face instability Tunnel Steinhaus

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Chienberg Tunnel Swisserland

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Chienberg Tunnel Swisserland

Crater due to tunnel face instability

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

Installation of sliding joint top hat section steel sets immediately behind the face of a tunnel behind advanced through very poor quality rock.

(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example: Spiling

Spiling in very poor quality, clay-rich, fault zone material(Photo: Hoek Rock Engineering, course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Tauerntunnel loose gravel

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Tauerntunnel loose gravel

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Strenger Tunnel (high deformations)

Damping elements

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Strenger Tunnel (high deformations)

Deformed damping elements

Undeformed damping elements

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Strenger Tunnel (high deformations)

Deformed damping element

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

Cables and shotcrete were used to support the roof of the power cavern in the Mingtan Pumped Storage Project in Taiwan. (Photo: Hoek Rock Engineering,

course notes)

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Trying to understand the rock mass behaviour

Investigations

� Field Investigations (e. g. geological field mapping, physical methods, etc.)

� Laboratory Investigations

� Numerical Investigations

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Cern

ChambersUX15: Span 35m

Heigth 42 mLength 56 m

USA15: Span 22 mHeigth 17 mLength 63 m

ShaftsPX16:

Diameter 13 mPX14:

Diameter 18 m

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Cern different excavation stages

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Cern displacements

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example Cern

Vertical displacement Plastic zones

Underground Excavation Design Part 1 Tunnel Design Introduction Alfred Zettler

Example

(Foto: Hoek Rock Engineering, course notes)