Flashcards in Conventional Breaching (Chapter 11) Deck (36)
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23. What are Opposed Counter Force charges effective against?
Effective against rectangular masonry or concrete columns 4’ thick or less
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15. What is the rounding rule of breaching radius for External Charge?
Round breaching radius UP to the nearest ½ foot
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If the amount of charge explosive is from 0 to less than 5 pounds, how thick would your charge be?
1 inches
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20. If N is equal to 2.5 or greater, how many charges should be use?
Round OFF to nearest whole number
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12. If concrete block with uncertain material factor, how would you identified it as?
Always assume as reinforced concrete
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10. For External Charges, Breaching Radius is equal to ____
The thickness of target
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18. If N is less than 1.25, how many charges should be used?
One charge
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11. How would determine if target material cannot be identified?
Assume target consists of strongest material in each specified groups
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14. The size of tamping should be…
Equal to or greater than Breaching Radius
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1. What is purpose of conventional breaching?
Used to destroy bridges, piers, abutements, and compound walls
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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
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16. What is the rounding rule of breaching radius for Internal Charge?
Round breaching radius UP to the nearest ¼ foot
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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
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25. How much build up require to prime counter force charge?
Blasting cap required ½” build up
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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)
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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)
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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
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6. If the amount of charge explosive is 40 pounds to less than 300 pounds, how thick would your charge be?
4 inches
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24. What is the formula for a counterforce charge?
Pounds = 1.5 x Breaching Radius
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5. If the amount of charge explosive is 5 pounds to less than 40 pounds, how thick would your charge be?
2 inches
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19. If N is greater than or equal to 1.25 and less than 2.5, how many charges should be used?
Two charges
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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
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7. If the amount of charge explosive is greater than 300 pounds, how thick would your charge be?
8 inches
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21. A counterforce charge relies on what?
Shockwave collision
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What is the intended effect when breaching?
To create spalling
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Will charges cut rebar reinforcement?
No, use P=D
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If a charge is 0 to less than 5 pounds, how thick should it be?
1 inch
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Define R in the breaching formula
Breaching radius is the thickness of material needed to be destroyed
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Define K in the breaching formula
The strength & hardness of the target material
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