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