Underground Excavation Design Shape

Underground Excavation Design Tunnel Design 2 Shape Alfred Zettler

Underground Excavation Design

Alfred Zettler

Differences to other fields of engineering design?

The main difference to other engineering disciplines is that in rock mechanics the material is pre-determined

Steel or concrete design: The material is determined.

It is possible to choose materials with different characteristics.

Tests are easy to perform and to determine (Young’s Modulus, strength, ect.).

Is it possible to influence the rock

mass behaviour?

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

Shape, Orientation and Support Measurements

To figure out the best shape and the best orientation is the most successful way to influence the rock mass behaviour around a tunnel.

Shape of the underground opening

Theoretical basis of underground constructions

Theoretical material

Theoretical Background

Mechanical Approaches

Continuum Mechanic

Discontinuum Mechanic

Fracture Mechanic

Theoretical approach

Continuum Mechanic Approach

Linear elastic material

Linear elastic - ideal plastic material:

� Mohr Coulomb material

� Hoek Brown material

� Drucker Prager material

Cylindrical Hole Infinite Elastic Medium

Example Borehole

Elliptic hole in an elastic medium

Elliptic hole in an elastic model

tress S

Elliptical Hole in an Elastic Medium

6,0-7,0

5,0-6,0

4,0-5,0

3,0-4,0

2,0-3,0

1,0-2,0

0,0-1,0

Estimation of Boundary Stresses

Spherical Cavity Elastic Medium

Mohr Coulomb Material

Cylindrical Hole Infinite Mohr-Coulomb Medium

Hoek–Brown Criterium

Cylindrical Hole Infinite Hoek–Brown Medium

Generalised Hoek – Brown Criterion

Stresses Shape and Primary Stress

Lined Circular Tunnel

Discontinuum Mechanics

Figure: Hoek Rock Engineering, course notes

Figure: Hoek Rock Engineering

Underground Excavation Design Alfred Zettler

References

Hoek, E., P.K. Kaiser, W.F. Bawden, “Support of Underground Excavations in Hard Rock”, Balkema, 1995

Wittke, W., B. Pierau, C.Erichsen, „Statik und Konstruktion der Spritzbetonbauweise“, Verlag Glückauf, 2002

Wittke, W. „Stability Analysis for Tunnels – Fundamentals“, Verlag Glückauf, 2000

„Empfehlungen des Arbeitskreises „Tunnelbau“ ETB“, Herausgeber Deutsche Gesellschaft für Geomechanik e.V., Verlag Ernst & Sohn, 1995

Jaeger, J.C., Cook, N.G.W., „Fundamentals of Rock Mechanics“, Chapmann and Hall Ltd., 1st edition 1969 or 3rd edition 1976

Wittke, W., “Rock Mechanics”, Springer or German Version “Felsmechanik”, Springer 1984

Girmscheid, G., “ Baubetrieb und Bauverfahren im Tunnelbau”, Verlag Ernst & Sohn, 2000

FLAC Manual Itasca Consulting Group

Underground Excavation Design Alfred Zettler

References

Hoek, E., “Practical Rock Engineering”, Download http://www.rocscience.com/hoek/pdf/Practical_Rock_Engineering.pdf

Underground Excavation Design Shape

Documents

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