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GE 5471 ROCK ENGINEERING CH 15 – Tunnel-Boring Machines

Dr. Norbert H. Maerz

Missouri University of Science and Technology

(573) 341-6714

norbert@mst.edu

Instructional Objectives

1. Select a method of excavation (tunnel boring or drill and blast) for a given situation.

2. Explain the components of a TBM machine.

3. Select a type of TBM for a given situation.

4. Define penetration rate, advance rate, availability, and utilization.

5. Classify the different types of cutters used in TBMs.

Tunnel Boring or Blasting?

• TBM– Smoother wall

– Stable profile

– Faster rate of advance

• BLASTING– No large capital outlay

– Cost effective for small operations

– Good for irregular geometries

TBM downsides

• If it doesn’t do the job you are in big trouble- capital outlay is gone, machine is sitting there - can’t back it out like a car in a garage

• Works well for any given rock type, but requires different machines for harder and softer rocks - problem where different rock types are encountered along the route-can’t just change the cutter head on a TBM

• Further problem when a heading straddles two rock types (“mixed ground” conditions)

• Susceptible to downtime for wear and tear• Susceptible to water inrushes

Components of TBM Operation

• Cutting tools

• Thrust/propulsion

• Mucking

• Support

Picture(s) from the collection of Dr. J. A. Franklin.

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Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

-Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

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Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

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Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin.

DEFINITIONS

• PENETRATION RATE - rate of advance while actually working– 7.3 m/hr shale, 1.3 m/hr dolomite– Depends on uniaxial compressive strength, fracture toughness, abrasion

hardness• ADVANCE RATE - average rate of advance over a fixed period of

time (includes downtime)– Typically less than 1m/hr, sometimes much less

• AVAILABILITY - percentage of time that the machine is available for operations (excluding breakdown and maintenance)

– Typically 60 - 90%• UTILIZATION - percentage of time that the machine is actually in use

(excluding also downtime for routine maintenance, tunnel lining, conveyor extension, operator change, etc.

– Typically 30 – 36%

Picture(s) from the collection of Dr. J. A. Franklin.

TBM Cutters

• Bladed for soil

• Chisels or drag bits for softer rock

• Disks, gear roller, studded cutters for the hardest rock

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Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin.

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Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

Picture(s) from the collection of Dr. J. A. Franklin.

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Picture(s) from the collection of Dr. J. A. Franklin. Picture(s) from the collection of Dr. J. A. Franklin.

SLIDE SHOW: Yucca Mt

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