Calc and Place > Conventional Breaching (Chapter 11) > Flashcards

Conventional Breaching (Chapter 11) Flashcards

(36 cards)

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1
Q
  1. What are Opposed Counter Force charges effective against?
A

Effective against rectangular masonry or concrete columns 4’ thick or less

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2
Q
  1. What is the rounding rule of breaching radius for External Charge?
A

Round breaching radius UP to the nearest ½ foot

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3
Q

If the amount of charge explosive is from 0 to less than 5 pounds, how thick would your charge be?

A

1 inches

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4
Q
  1. If N is equal to 2.5 or greater, how many charges should be use?
A

Round OFF to nearest whole number

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5
Q
  1. If concrete block with uncertain material factor, how would you identified it as?
A

Always assume as reinforced concrete

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6
Q
  1. For External Charges, Breaching Radius is equal to ____
A

The thickness of target

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7
Q
  1. If N is less than 1.25, how many charges should be used?
A

One charge

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8
Q
  1. How would determine if target material cannot be identified?
A

Assume target consists of strongest material in each specified groups

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9
Q
  1. The size of tamping should be…
A

Equal to or greater than Breaching Radius

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10
Q
  1. What is purpose of conventional breaching?
A

Used to destroy bridges, piers, abutements, and compound walls

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11
Q
  1. What is the formula to find the number of charges?
A

N = W / (2R)

Number of charges = Width / (2 x Radius)

N = number of charges
W = width of pier, slab, or wall
R = breaching radius in feet

Use this formula in Step 5

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12
Q
  1. What is the rounding rule of breaching radius for Internal Charge?
A

Round breaching radius UP to the nearest ¼ foot

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13
Q
  1. If you required to destroy a mason building with uncertain material, what will be the K (constant material factor)?
A

Assume it as first class masonry

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14
Q
  1. How much build up require to prime counter force charge?
A

Blasting cap required ½” build up

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15
Q
  1. What are the considerations of counterforce charges?
A

Charges should be diametrically opposed (explosive divided into 2 equal parts)

Obstacle must have at least 3 free faces or be freestanding

Relies on shockwave collision

Round measurements UP to next 1/2 foot (External charge)

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16
Q
  1. What are the critical factors in conventional breaching? Which are most important?
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A

Size, shape, placement, and tamping

Size and confinement are most critical factors

(charges will not cut rebar reinforcement)

17
Q
  1. What is the formula for breaching charges?
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A 
P = R^3 KC
(Pound = route 3 to Kansas City)

(Pound = Breaching Radius^3 x Constant for material factor x Tamping factor

18
Q
  1. If the amount of charge explosive is 40 pounds to less than 300 pounds, how thick would your charge be?
19
Q
  1. What is the formula for a counterforce charge?
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A

Pounds = 1.5 x Breaching Radius

20
Q
  1. If the amount of charge explosive is 5 pounds to less than 40 pounds, how thick would your charge be?
21
Q
  1. If N is greater than or equal to 1.25 and less than 2.5, how many charges should be used?
22
Q
  1. For Internal Charges, Breaching Radius is equal to ____
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A

½ the thickness of the target (for charges placed at center mass)

Remaining thickness of the target not drilled if not placed at center of mass

23
Q
  1. If the amount of charge explosive is greater than 300 pounds, how thick would your charge be?
24
Q
  1. A counterforce charge relies on what?
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A

Shockwave collision

25
What is the intended effect when breaching?
To create spalling
26
Will charges cut rebar reinforcement?
No, use P=D
27
If a charge is 0 to less than 5 pounds, how thick should it be?
1 inch
28
Define R in the breaching formula
Breaching radius is the thickness of material needed to be destroyed
29
Define K in the breaching formula
The strength & hardness of the target material
30
Define C in the breaching formula
Tamping factor, which depends on charge location and tamping materials used
31
Tamping factors
Depends on location and tamping material Do not consider a charge fully tamped with a solid material unless it is covered at a depth equal to or greater than the breaching radius
32
Methods of attachment for external charges
Hydra-gel Breachers tape Rope Prop sticks
33
How should you round measurements for counterforce charges?
Round UP to nearest 1/2 foot (External charge)
34
How should you prime and detonate a counterforce charge?
Prime and detonate simultaneously rear center with blasting caps and 1/2 inch build up.
35
What is the formula to cut rebar reinforcement?
P = D
36
What explosive effect do concrete breaching charges create?
Spalling
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