Conventional Breaching (Chapter 11) Flashcards Preview

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Flashcards in Conventional Breaching (Chapter 11) Deck (36)
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1

23. What are Opposed Counter Force charges effective against?

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

2

15. What is the rounding rule of breaching radius for External Charge?

Round breaching radius UP to the nearest ½ foot

3

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

1 inches

4

20. If N is equal to 2.5 or greater, how many charges should be use?

Round OFF to nearest whole number

5

12. If concrete block with uncertain material factor, how would you identified it as?

Always assume as reinforced concrete

6

10. For External Charges, Breaching Radius is equal to ____

The thickness of target

7

18. If N is less than 1.25, how many charges should be used?

One charge

8

11. How would determine if target material cannot be identified?

Assume target consists of strongest material in each specified groups

9

14. The size of tamping should be…

Equal to or greater than Breaching Radius

10

1. What is purpose of conventional breaching?

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

11

17. What is the formula to find the number of charges?

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

12

16. What is the rounding rule of breaching radius for Internal Charge?

Round breaching radius UP to the nearest ¼ foot

13

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

Assume it as first class masonry

14

25. How much build up require to prime counter force charge?

Blasting cap required ½” build up

15

22. What are the considerations of counterforce charges?

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)

16

2. What are the critical factors in conventional breaching? Which are most important?

Size, shape, placement, and tamping

Size and confinement are most critical factors

(charges will not cut rebar reinforcement)

17

3. What is the formula for breaching charges?

P = R^3 KC
(Pound = route 3 to Kansas City)

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

18

6. If the amount of charge explosive is 40 pounds to less than 300 pounds, how thick would your charge be?

4 inches

19

24. What is the formula for a counterforce charge?

Pounds = 1.5 x Breaching Radius

20

5. If the amount of charge explosive is 5 pounds to less than 40 pounds, how thick would your charge be?

2 inches

21

19. If N is greater than or equal to 1.25 and less than 2.5, how many charges should be used?

Two charges

22

9. For Internal Charges, Breaching Radius is equal to ____

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

7. If the amount of charge explosive is greater than 300 pounds, how thick would your charge be?

8 inches

24

21. A counterforce charge relies on what?

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