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Chapter 26
TABLE 26-1
Quantity-Disiance Relationships
for Specified Yalues of Peak Particle Yelacity
under Average Field Contlitions
For Open Face Blasting
Charge Weight per Delay Period - Lps,
Distance-Ft. 0.5 ips 1 ips pips
20 0.3 0.7 1,7
30 0.7 1.6 3.8 ;~
40 1.2 2.8 6.7 ,
50 1.8 4.4 10.4
60 2,7 6.3 15.0
70 3.6 8.6 20.5
80 4.7 71.2 26.7
90 6.0 14.2 33.9
100 7.4 17.6 41.8
120 10.6 25.3 60.2
140 14,5 34.4 819
160 18.9 45.0 107.0
180 23.9 56.9 735.4
200 29.6 70.3 167.2
240 42.6 101.2 240.7
Z80 57,9 137.8 327.7
320 75,7 779.9 428.0
360 95.8 227.7 547.7
4D0 118,2 281.2 668.7
NOTE: Particle velocities shown may be higher by a factor of two or more
untler some geological conditions and may be higher by a lactor of
five or more under conditions of high confinement, such as the open-
ingholes in a heading or in presplitting.
If seismic guidelines are not established by the operator's insurance
company, state or local laws, or other agencies, blasters may consult
structural engineers who aze able to specify permitted vibration levels
for certain structures or kinds of structures. The quantity-distance
relationships for peak particle velocities of 0.5, 1.0 and 2.0 inches-
per-second in Table 26-1 may be used as a guideline to select charge
430
Vibration and Notse
TABLE 26.2
Permitted Quantity-Distance Relationships
without Seismograph Measurements
Adopted by Several States
Charge Weight per Delay Period
Distance-Ft. of 0 MS or Greater-Lbs.
0-10 0.12'
11-15 0.25
16-20 0.50
21-25 0.75
26-30 1.00
40 2.25 .
50 3.50
60 4.75
70 6.00
80 7.25

~ 100 9.75
6 120 12.25
J.. 140 14.75
,';! 160 17.25
180 19.75
~.~ 200 22.25
220 25.75
240 27.25
260 29.75
280 32.25
300 34.75
'Total shot
•
weights Cor specific distances. Modifications can be made on the job as
seismograph readings become available.
Regulations for some states, e.g., Pennsylvania, prescribe
quantity-distance relationships in the absence of seismic measure-
' ments. They use a sliding scaled distance ranging from about 20
- teetlpound""- at small distances to 50 feet pound"= at a distance of 300
feet or more for blasting operations not using seismograph coverage.
Table 26-2 shows permitted values which have been adopted by sev-
eral states.
There are several steps an operator can take to reduce blast vibra-
tion. Some of these are:
~` 431