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BWT 210 > Chapter 3 - Rock excavation > Flashcards

Chapter 3 - Rock excavation Flashcards

1
Q

Classifications of rock

A

Igneous/ Sedimentary/ Metamorphic

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2
Q

Igneous rock formed?

A

When earths molten material cooled.

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3
Q

Examples of Igneous rock

A

Granite & basalt

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4
Q

What rock is most difficult to excavate?

A

Igneous rock

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5
Q

Sedimentary rock formed?

A

Precipitation of material from water & air. Highly satisfied & has many planes of weakness. (Sandy granules)

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6
Q

Most easily excavated rock?

A

Sedimentary rock

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7
Q

Examples of Sedimentary rock

A

Sandstone/ shale/ limestone

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8
Q

Metamorphic rock formed?

A

Originated as igneous/ sedimental rock, but been change by heat, pressure or chemical action

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9
Q

Examples of metamorphic rock

A

slate/ marble

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10
Q

Difficulty in excavating rock depends on?

A

Number of factors in addition to type

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11
Q

Factors of difficulty in excavation rocks

A

Extent of fractures (&other plane of weakness)
Whether rock has crystalline structure
Amount of weathering occurred
Predominant grain size
Rock brittleness
Rock hardness

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12
Q

How is relative hardness of rock measured?

A

Mohs scale from 1 (talc) to 10 (diamond)

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13
Q

Rule about rock investigation

A

Any rock that can be scratched by knife blade (harness about 5) can easily by excavated by ripping/ other mechanical method.

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14
Q

What is required to evaluate (hard) rock characteristics?

A

Investigation report - to choose right equipment

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15
Q

What are the principal methods for investigating subsurface conditions?

A

Drilling
Excavating test pits
Seismic measurements

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16
Q

What are the processes of moveing rocks?

A

Loosening
Loading
Hauling
Compacting

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17
Q

Loosening

A

Blasting, chemical or mechanical procedures

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18
Q

What influence choice of equipment for loading/ hauling/ compacting?

A

Loadability

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19
Q

What is the traditional method for excavating rock?

A

Drilling blat holes in rock
Loading holes with explosives
Detonating explosives
Loading fractured rock into haul units with power shovels
Hauling rock away in trucks

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20
Q

What is the newer alternative method for excavating rock?

A

Tractor-mounted rippers to loosen rock
Wheel loaders to load fractured rock into haul units
Reinforced scrapers to load & haul fractured rock

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21
Q

How is tunneling in rock form?

A

Drilling & blasting to form specialized form of rock excavation

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22
Q

What is recently used for tunneling?

A

Machines or mechanical moles equipped with multiple cutter heads = capable of excavating full tunnel.

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23
Q

Advantages of hydraulic drills

A

Penetrate faster
Consume less energy
Produce less noise & dust

24
Q

Raise boring

A

A drilling technique in which a large diameter hole is drilled upwards from the bottom.

25
Q

Procedures of raise boring

A
  1. Pilot hole is drilled from surface into mine/ other underground cavity.
  2. Large reaming head is attached to lower end of raise boring machine drill string which has been lowered into the shaft.
  3. Large diameter hole is created as the reaming head is rotated and raised by the raise boring machine sitting on the surface.
26
Q

How is rock drills traditionally been powered?

A

Compressed air

27
Q

What type of material is used to manufacture drill bits to drill through diamond.

A

Polycrystalline diamond (PCD)

28
Q

How is a PCD drill bit made?

A

Consists of tiny diamond particles bonded together by a sintering process to create a hard, durable material

29
Q

Principal explosives used for rock excavations

A

Dynamite
Ammonium nitrate
Ammonium nitrate in fuel oil (ANFO)
Slurries

30
Q

Slurries

A

Mixtures of gels, explosives & water.
May contain powered metals to increase blast energy.

31
Q

Detonators used to initiate explosion include which type of caps?

A

Electric & non-electric caps

32
Q

What type of wires us used to make up electric blasting circuits?

A

Legwires
Buswires
Connecting wires
Firing lines

33
Q

How can electric blasting circuits be connected

A

Series
Parallel
Parallel-series

34
Q

Legwires

A

two wires that form integral part of each electric blasting cap

35
Q

Buswires

A

are used to connect legwires of caps into parallel of parallel-series circuits

36
Q

Connecting wires

A

are used to connect legwires/ buswires to firing line

37
Q

Firing lines

A

consist the power source of 2 parallel conductors that connect the power source to remainder of the blasting circuit.

38
Q

Blasting is controlled by?

A

Government regulations

39
Q

Major safety precautions for blasting

A
  1. Storage magazines for explosives should be located in isolated areas
  2. Detonators must be stored in separate containers
  3. Electric blasting should not be connected to power source
  4. Permit no radio transmission in electric blasting circuit
  5. Protect detonators from all physical harm
  6. Check blast holes before loading (hot rock/ steel = explosion)
  7. Do not drop/ tamp primed charges.
  8. Only use non-metallic tools for tamping
  9. Clear signals for blasting
  10. Wait at least 1h before investigating a misfire.
40
Q

Advantages of ripping

A

Less expensive than drilling/ blasting
Increased production
Fewer safety hazards
Reduced insurance cost

41
Q

Parallelogram ripper

A

Maintains constant angle with ground as raised and lowered.

42
Q

Automatic ripper

A

Control ripping depth & vary tip angle as raised and lowered.

43
Q

Upper hydraulic cylinder tip angle

A

Permits tip angle to be varied as desired to obtain optimum results

44
Q

Different tip angles

A

Penetrate surface
Produces optimum rock breakage

45
Q

Impact rippers

A

Utilize hydraulic mechanism to impact a hammering action.
Increase ripper production.

46
Q

What needs to be considered when ripping

A

Speed & depth
Spacing of ripper passes
Number of shanks to be used to max production

47
Q

On what depends the number of shanks to be used to max ripped production?

A

Rock type
Tractor power
Depth of ripping

Number of shanks should be number that yields the desired penetration (without straining tractor)

48
Q

What needs to be considered to choose rip direction?

A

Rip downhill - gravity advantage
Rip uphill - ripping laminated material

49
Q

Why rip uphill when ripping laminated material

A

To enable ripper teeth to penetrate under layers

50
Q

How to rip limestone

A

Use dozer with ripper attachment

51
Q

Depth of ripping depend on

A

Number of shanks used & tractor power

Stratified material - match ripping depth with layer thickness

52
Q

What should be considered with ripping speed?

A

Speeds needs to be kept low - to reduce wear on ripping teeth & shanks.

53
Q

Compressed air

A

Used as a power source for construction tools & equipment.
Used to clean out drill hole.

54
Q

Hydraulic power

A

Power source for rock drilling.

55
Q

Uses for compressed air in construction

A

Paint spraying
Pneumatic application of concrete (shotcrete)
Conveying cement
Pumping water
Operating pneumatic tools

56
Q

Pneumatic tools that use compressed air

A

Spaders (trench diggers)
Concrete vibrators
Drills
Grinders
Hammers
Paving breakers
Sandblasting guns
Saws
Staple guns
Nailers
Tampers
Wrenches

57
Q

Examples of pumps & water supply systems utilize in construction

A

Dewatering excavations
Mixing & curing of concrete
Aiding soil compaction
Jetting spiles into place
Supply water

BWT 210 (5 decks)

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