CES Assessment & Evaluation Techniques 3

Question 1

The scaled distance formula used in blast vibration assessment relates which variables?

Accepted Answer

Maximum charge weight per delay and distance from the blast

Answer

Scaled distance (SD) = Distance / √(Maximum Charge Weight Per Delay), and is the key formula used to predict and evaluate ground vibration compliance.

Question 2

Which document serves as the primary reference for evaluating structural damage risk from blasting vibrations in the United States?

Accepted Answer

OSMRE guidelines and USBM RI 8507

Answer

USBM (U.S. Bureau of Mines) Research Investigation 8507 established the scaled distance and PPV limits widely adopted by OSMRE for structural damage risk evaluation.

Question 3

In evaluating detonator performance, electric resistance testing serves what primary purpose?

Accepted Answer

Confirming circuit continuity and identifying faulty detonators before firing

Answer

Resistance testing of electric detonator circuits confirms continuity and identifies open circuits, shorts, or out-of-tolerance units before firing, preventing misfires.

Question 4

A blasting crew reports excessive flyrock during a quarry shot. Which evaluation factor should be examined FIRST?

Accepted Answer

Stemming length and material adequacy

Answer

Inadequate stemming is the most common cause of flyrock, as insufficient confinement allows explosive gases to vent prematurely and propel rock fragments.

Question 5

When assessing airblast overpressure from a surface blast, the maximum acceptable level for residential structures is typically:

Accepted Answer

133 dBL (linear)

Answer

USBM research established 133 dBL as the airblast overpressure level below which residential structural damage is unlikely, and this is the standard regulatory threshold.

(CES) Certified Explosives Specialist Practice Test

(CES) Certified Explosives Specialist Practice Test

CES Assessment & Evaluation Techniques 3