CA1315868C - Blast recorder and method of displaying blast energy - Google Patents
Blast recorder and method of displaying blast energyInfo
- Publication number
- CA1315868C CA1315868C CA000569428A CA569428A CA1315868C CA 1315868 C CA1315868 C CA 1315868C CA 000569428 A CA000569428 A CA 000569428A CA 569428 A CA569428 A CA 569428A CA 1315868 C CA1315868 C CA 1315868C
- Authority
- CA
- Canada
- Prior art keywords
- blast
- signals
- velocity
- peak
- band
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D7/00—Indicating measured values
- G01D7/02—Indicating value of two or more variables simultaneously
Abstract
ABSTRACT
A blast recorder and method for monitoring and processing vibrations from blasts, and for displaying the results in a nearly real time basis and in a manner which is easily interpreted by a relatively unskilled field worker and corresponds to a form which closely correspond to the real damage causing aspect of the blast than heretofore. The invention operates by receiving seismic energy signals from a blast sensor, processing the energy signals to obtain velocity signals relating to said blast, filtering either the energy signals prior to, or the velocity signals following said processing step, into high and low frequency bands, to obtain high and low band velocity signals, integrating over the period of the blast the high and low band velocity signals to obtain high and low band displacement signals, determining the peak velocity signal in each band, over the period of the blast, and displaying one or all of the peak of the velocity signal determined in the high frequency band, the peak of the velocity signal determined in the low frequency band, and the displacement signal related to the low frequency band.
A blast recorder and method for monitoring and processing vibrations from blasts, and for displaying the results in a nearly real time basis and in a manner which is easily interpreted by a relatively unskilled field worker and corresponds to a form which closely correspond to the real damage causing aspect of the blast than heretofore. The invention operates by receiving seismic energy signals from a blast sensor, processing the energy signals to obtain velocity signals relating to said blast, filtering either the energy signals prior to, or the velocity signals following said processing step, into high and low frequency bands, to obtain high and low band velocity signals, integrating over the period of the blast the high and low band velocity signals to obtain high and low band displacement signals, determining the peak velocity signal in each band, over the period of the blast, and displaying one or all of the peak of the velocity signal determined in the high frequency band, the peak of the velocity signal determined in the low frequency band, and the displacement signal related to the low frequency band.
Description
~3~l5~
01 Thi8 invention is related to blast 02 recorders, and particu]arly -to a blast recorder useful 03 for monitoring the vibrations from blasts used in 04 construction, to ensure that they meet the 05 requirements of the law, the owners of adjacent 06 buildings, the user of the recorder, and of the 07 environment.
08 When blasting rock, e.g. for construction, 09 it is important to ensure that vibrations imparted from the blast through the earth to adjacent buildings 11 are below predetermined levels, and can be proven so 12 by a recording.
13 It had been believed that s~ructure 14 resonances are important to be considered when determining the maximum safe energy sustainable by a 16 residential structure being subjected to environmental 17 blasts. However in recent years it was determined 18 that at other frequencies it is the peak displacement 19 of particles with respect to particle velocity that is the safety determining factor. The U.S. Bureau of 21 Mines, in report RI-8507 (Novernber 19~0) specified the 22 safety limits for residential buildings subjected to 23 blast vibrations. In these criteria, above 40 Hz a 24 constant peak particle velocity of 2.0 in/sec. is indicated to be the maximum safe value. Below 40 Hz, 26 the maximum safe particle velocity decreases at a rate 27 equivalent to a constant peak displacement of 28 0.008 in. At frequencies corresponding to about 4 to 29 15 Hz, constant particle velocities of .75 in/sec. for drywall and 0.50 in/sec. for plaster, are again a 31 determining safety factor. Below 4 Hz, a maximum 32 particle displacement of 0.03 in. is recommended.
33 To determine the vibration sustainable by 34 a building, seismic sensors have been used, typically located in three mutually orthogonal axes. Previous 36 systems perform Fourier transforms of the sensed 37 vibrations from the sensors to obtain a spectrum ~ 3 ~
01 analysis of the sensed vibrations. ~ecause Fourier 02 analyses are performed, which takes many digital 03 computing hours, the recorded data slgnals were 04 recorded and transported to a laboratory for analysis.
05 Clearly if damaging blasts were created, 06 the blasting personnel would have no knowledge of this 07 until many hours or a day or more following the 08 blasts, due to the required computing time. By this 09 time the blasts could have produced great damage in adjacent structures. The alternative would be to wait 11 until each blast had been analyzed. This would take 12 excessive amounts of time, and would not allow the 13 blasting to be completed within a reasonable interval, 14 slowing the work and substantially increasing the costs.
16 While a spectrum analysis is provided as a 17 result of the Fourier analysis, the data can vary 18 depending on the frequency channel widths in which the 19 data are gathered. ~hus different equipment, having different channel widths or different center 21 frequencies, or with slight differences in ad]ustment, 22 would produce different results. Accordingly there 23 could be no legally reliable measurement results, and 24 the results are clearly subject to abuse.
In addition, the prior art systems, while 26 producing a Fourier analysis, did not provide a result 27 relating to the particle displacement. Thus it was 28 impossible to know whether the aforenoted 0.008 29 particle displacement below 40 Hz or 0.030 in. below 4 Hz was met.
31 Clearly prior art systems for attempting 32 to determine and record seismic energy transmission 33 from a blast were neither practical nor accurate in 34 the field.
The present invention is a blast recorder 36 which determines on a virtually real time basis 37 whether the recommendations of both maximum particle 1 3 ~ 5~
01 velocity and displacement are met. E'urther, the 02 invention apparatus can be produced 50 light and 03 portable that it can be used in the field. Thus the 04 characteristics of the seismic energy can be 05 determined and recorded as proof oE the blast, 06 immediately following a blast. If the blast energy 07 exeeds the recommended values of particle velocity and 08 particle displacement, corrective action can be taken 09 immediately, th~reby avoiding additive damage to nearby buildings.
11 In accordance with a preferred embodiment, 12 the blast recorder is comprised of apparatus for 13 sensing seismic vibrations of a blast, and for 14 providing a velocity signal corresponding to the particle velocity relating to the vibrations. The 16 apparatus for sensing seismic vibrations are 17 preferably sensors. However the sensors can be lS accelerometers followed by integrators, or 19 displacement sensors followed by differentiators, for outputting a velocity signal corresponding to the 21 particle velocity relating to the vibrations. Filters 22 filter each velocity signal into a high and a low 23 frequency band. The velocity signal of each band is 24 then integrated in integrators to determined high and low band displacement signals. The maximum velocity 26 signal in each band is determined, and one or all of 27 the maximum velocity signal determined in the high 28 frequency band, the displacement signal related to the 29 high frequency band, the maximum velocity signal determined in the low frequency band, and the 31 displacement signal related to the low frequency band, 32 are displayed. Preferably the last-noted signals are 33 displayed graphically by printing on a callibrated 34 graph on a printer, but can alternatively or additionally be displayed on a graphical display 36 (e.g. liquid crystal) and numeri.cally either on the 37 instrument display or printer. The signals can also 38 - 3 ~
01 be stored in a local rnemory for more detailed later 02 analyses. Preferably the graphical display is in 03 exactly the form given by the U.S. Bureau of Mines, 04 and is displayed on the same display as the 05 recommended values. In the case that the sensors are 06 accelerometers followed by integrators or displacement 07 sensors followed by differentiators, the filtering can 08 be effected either prior or following integration or 09 differentiation. Further all or some of the signal processing can be done in a microprocessor. If 11 desired, the output signals of the sensors can be 12 recorded for later processing or analysis.
13 A better understanding of the invention 14 will be obtained by reference to the detailed description below, with reference to the following 16 drawings, in which:
17 Figure 1 is a graph representing the 18 maximum safe particle velocities and particle 19 displacements are various frequencies from 1 to 100 Hz, 21 Figure 2 is a reproduction of Figure 1, on 22 which are plotted various curves showing the results 23 of prior art and the present system, 24 Figure 3 is a block schematic of the 25 preferred embodiment of the present invention, and 26 Figures 4-7 are block schematics of other 27 embodiments of the invention.
28 Turning to Figure 1, a graph of maximum 29 safe particle velocity against frequency is shown.
The graph shows that the maximum safe peak particle 31 velocity above 40 Hz is 2.0 in/sec., shown by curve 32 portion A. Below 40 Hz the maximum safe velocity 33 decreases at a rate equivalent to a constant peak 34 displacement of 0.008 in., shown by graph portion B.
Below 15 Hz, the maximum recommended peak particle 36 velocity is .75 in/sec. ~or drywall (curve C), and 37 0.50 in/sec. for plaster (shown as curve portion D).
38 _ ~ _ ~ 3 ~
01 Below about 4 H~. the particle displacement above 02 0.030 in. is considered to be dangerous, this curve 03 portion being designated as E. The graph is speciEic 04 in form, but the safe maxima and slopes are variable, 05 depending on the building struc-ture and location, and 06 thus on its sensitivity.
07 Figure 2 is a reproduction of the 08 aforenoted curve. However in this case a curve F has 09 been superimposed, representing the actual particle velocity with frequency occurring as a result of a 11 blast.
12 As noted earlier, prior art systems 13 perform a spectrum analysis of the particle velocities 14 across the entire frequency spectrum. In performing such analyses, integrations of the particle velocities 16 within successive defined very narrow frequency bands 17 centered at e.g. frequency G, and having bandwidths BW
18 are performed, after recording the seismic signal from 19 each sensor. Within each BW segment, the energy is totalled, and a plot or listing of the values is made, 21 in an attempt to reproduce curve F.
22 As noted earlier, such a procedure takes 23 hours and also involves the use of a large capacity 24 computer. Furthermore, this system does not provide any indication of the displacement, as a requirement 26 in curve graph sections B and E (Figure 1), and thus 27 omits a significant determination of whether the 28 safety limits have been exceeded.
29 In addition, the interpretation of a curve such as a curve F, and how it relates to a curve such 31 as that shown in Figure 1 cannot be done by relatively 32 unskilled field personnel, especially since parts of 33 curve F bear no relationship to the units of curve 34 portions B and E.
In the present invention an output display 36 can be created which corresponds both to the form and 37 to the units of the safe criteria maxima prescribed by 1 3 ~
01 the U.S. Bureau of Mines. The output display of the 02 present inven-tion is shown in Figure 2, which shows 03 the results of the blast in representative curve 04 sections A' corresponding to curve portion A, B' 05 corresponding to curve portion B, C' corresponding to 06 curve portion C or D, and curve portlon E' 07 corresponding to curve portion E.
08 The above result is obtained in the 09 present invention by filtering the sensor output signal as it is received, splitting it into a high 11 band signal preferably above about 15 Hz, and a low 12 band signal, below about 15 Hz.
13 In the preferred embodiment, received 14 velocity sensor ou-tput signals in the high band and low frequency bands are integrated, resulting in 16 displacement signals. The peak velocity signal in 17 each of the respective bands i5 printed, displayed or 18 plotted as curve portions A' and C' respectively, and 19 are merely horizontal lines at the peaks conforming to the form of curve portions A and C. The displacement 21 signals for the high and low frquency bands are 22 printed, displayed or plotted as curve portions B' and 23 E'.
24 The curve portions A', B', C' and E' are preferably presented on a CRT or LED display with a 26 curve representing the allowable maxima, that is curve 27 portions A, B, C and/or D and E. Thus for a 28 particular blast the curve 1, representing the 29 allowable maxima, and curve 2, representing the results of a particular blast, are displayed 31 together. An unskilled worker can thus immediately 32 determine whether a particular blast exceeds the 33 allowable maxima of either or both particle velocity 34 or particle displacement. Further, since the determination is made in real time, there is no delay 36 involved in adjusting the blast parameters, as was 37 required in the prior art.
~ 3 ~
01 Figure 3 illustrates the preferred 02 embodiment of the presen-t invention. A representative 03 seismic sensor 3 provides an output velocity signal to 04 low and high pass filters 4 and 5. Preferably three 05 separate sensors in three mutually orthogonal axes are 06 used for sensing seismic energy in three mutually 07 orthogonal directions. Preferably t.he output signal 08 of each sensor is treated separately, but the vactor 09 sum of all three sensors could be used in certain cases. The resulting output signal of each sensor is 11 applied to low and high pass filters 4 and 5. The low 1~ pass filter passes all input signals below about 13 1~ Hz, while the high pass filter passes signals above 14 about 15 Hz. However the particular bands used can be different from the above to suit the circumstances.
16 The output signals of low and high pass 17 filters 4 and 5 are applied to analog to digital 18 converter 6. The output signal of low pass filter 4 19 is also applied to integrator 7, and the output signal of high pass filter 5 is applied to integrator 8. The 21 output signals of integrators 7 and 8, representing 22 displacements, are applied to the analog to digital 23 converter 6, along with the output signals of low and 24 high pass filters 4 and 5 which represent the velocity.
26 ~nalog to digital converter 6 converts the 27 four singals input to it into a digital form for 28 application to a central processing unit 9 to which is 29 connected a memory 10, a display 11, and a keypad 12.
The display is representative of one or more of 31 several forms of displays, such as an LCD graphical 32 display, which may or may not include an alphanumeric 33 display of the values displayed, andlor a printer, for 34 providing hard copy of the displayed data.
Memory 10 is used by the CPU 9 to store 36 operation programs, and also to store the data to be 37 displayed, in a well known manner.
1 3 ~
01 The channels each comprised of the low 02 pass Eilter, integrator and connection from the low 03 pass ~ilter to A/D converter 6 are preferably 04 reproduced for each mutually or-thogonal seis~ic 05 sensor, and the vector sum of the signals from the A/D
06 converter determined by the CPU 9. Alternatively the 07 sensor 3 outputs a vector sum of the energy received 08 and provides a signal into the circuit shown.
09 It should also be noted that the vector summation, low pass filtering and in-tegration can be 11 performed by the CPU itself. In that case Figure 3 12 should be considered as a representative block diagram 13 illustrating the algorithm to be perEormed in 14 obtaining the signal forms required by the CPU in order to form the display of the graph 2 shown in 1~ Figure 2, except that analog to digital conversion can 17 be performed with the output signals of the sensors, 18 prior to filtering, rather than following, as shown.
19 The signals representative of the constants in the various portions of graph 1 also to be displayed in 21 display 11 can be prestored in memory 10 by entering 22 them by means of keypad 12 connected to CPU 9.
23 Thus in operation the entire apparatus, 24 preferably packaged in a suitcase sized instrument is taken to the field, and the sensor unit compxised of 26 seismic sensors in three mutually orthogonal axes is 27 placed where it can sense the ground vibrations. The 28 blast is set off. The resulting signal from each 29 sensor 3 is applied to corresponding low and high pass filters 4 and 5, and split into high and low frequency 31 bands. The output signals of low and high pass 32 filters 4 and 5 are applied to A/D converter 6, and 33 are also applied to integrators 7 and 8. The 34 integrated output signals of integrators 7 and 8 are also applied to A/D converter 6. The digitized 36 resulting output signals are applied to CPU 9.
37 In CPU 9 in conjunction with memory 10, 3~ - 8 -~ 3 ~
01 the digitally converted signals are vector summed, and 02 a determination is made of the peak energy during the 03 blast interval in the hlgh frequency band, e.~. a~ove 04 15 Hz, and the peak energy in the low frequency band, 05 e.g. below 15 Hz. These peak energies are displayed 06 or plotted as horizontal lines A' and C' respectively.
07 The energies in each of the high and low 08 bands is summed, and integra-ted, to obtain peak 09 displacements in the low and high frequency bands during the blast, which are plot-ted as the sloped ll lines E' and B' respectively on the same display, the 12 slope of the lines E and B being the integrals of the 13 energy in each of the bands. Where the lines B' and 14 C' intersect, they are terminated, and where the lines E' and C', and B' and A' intersect, they are 16 terminated, to form a continuous plot.
17 As noted earlier, the values representing 18 the line segments representing the particle velocity 19 and displacement danger maxima are prestored in memory. These are displayed on display ll as line 21 segments A, B, C and E at the same time as line 22 segments A', B', C' and E'.
23 The result is an easy to read display 24 which corresponds substantially to the curve form representing the particle velocity and displacement 26 values recommended by the U.S. Bureau of Mines, and 27 are readily understandable by an unskilled worker in 28 the field.
29 In addition, the display is made available immediately after the blast, avoiding the requirement 31 for laboratory analyses of the seismic data to 32 determine whether the blast criteria have been 33 exceeded. Yet if desired, the sensor output signals 34 can be recorded, and carried to a laboratory for later analysis if desired, whereupon the recorded signals 36 are input into the apparatus as sensor signals.
37 In accordance with other embodiments, as 38 _ 9 _ .
~3~5~
01 shown in Figure 4, -the ~ensor 3A is an accelerometer 02 13, feeding an acceleration signal into an inteyrator, 03 which outputs a velocity signal to low and high pass 04 filters 4 and 5 as in Figure 3. The remainder of this 05 embodiment is as in Figure 3.
06 As shown in Figure 5, the sensor is a 07 displacement sensor, Eeeding a displacement signal 08 into a differentiator, which outputs a velocity signal 09 to low and high pass filters 4 and 5 as in Figure 3.
The remainder of this embodiment is as in Figure 3.
11 As shown in Figure 6, the sensor is an 12 accelerometor, feeding an acceleration signal into low 13 and high pass filters 7A and 8A, which band limit the 14 signal into the bands such that after integration in integrators 13A and 13B it corresponds to the velocity 16 signal bands output from filters 7 and 8. The signals 17 from the integrators 13A and 13B are fed to 18 integrators 7 and 8 and A/D 6 as in Figure 3, to which 19 the remainder of this embodiment corresponds.
As shown in Figure 7, the sensor is a 21 displacement sensor, feeding a displacement signal 22 into low and high pass filters 7B and 8B, which band 23 limit the signal into the bands such that after 24 diEferentiation in differentiators 14A and 14B, it corresponds to the velocity signal bands output from 26 filters 7 and 8. The signals from differentiators 14A
27 and 14B are fed to integrators 7 and 8 and A/D 6 as in 28 Figure 3, to which the remainder of this embodiment 29 corresponds.
It should also be noted that any of these 31 embodiments can be implemented as an algorithm in a 32 computer, processing the signals received from the 33 various sensors, as described above.
34 The result is a a relatively inexpensive, portable instrument which is highly useful for 36 practitioners in the blasting field, and, i-t is 37 believed, represents a significant advance in the art.
~ 3 ~
01 A person understanding this invention may 02 now conceive of various alternative structures or 03 variations thereof, using the principle described 04 herein. All are considered to be within the sphere 05 and scope of the invention as defined in the claims 06 appended hereto.
01 Thi8 invention is related to blast 02 recorders, and particu]arly -to a blast recorder useful 03 for monitoring the vibrations from blasts used in 04 construction, to ensure that they meet the 05 requirements of the law, the owners of adjacent 06 buildings, the user of the recorder, and of the 07 environment.
08 When blasting rock, e.g. for construction, 09 it is important to ensure that vibrations imparted from the blast through the earth to adjacent buildings 11 are below predetermined levels, and can be proven so 12 by a recording.
13 It had been believed that s~ructure 14 resonances are important to be considered when determining the maximum safe energy sustainable by a 16 residential structure being subjected to environmental 17 blasts. However in recent years it was determined 18 that at other frequencies it is the peak displacement 19 of particles with respect to particle velocity that is the safety determining factor. The U.S. Bureau of 21 Mines, in report RI-8507 (Novernber 19~0) specified the 22 safety limits for residential buildings subjected to 23 blast vibrations. In these criteria, above 40 Hz a 24 constant peak particle velocity of 2.0 in/sec. is indicated to be the maximum safe value. Below 40 Hz, 26 the maximum safe particle velocity decreases at a rate 27 equivalent to a constant peak displacement of 28 0.008 in. At frequencies corresponding to about 4 to 29 15 Hz, constant particle velocities of .75 in/sec. for drywall and 0.50 in/sec. for plaster, are again a 31 determining safety factor. Below 4 Hz, a maximum 32 particle displacement of 0.03 in. is recommended.
33 To determine the vibration sustainable by 34 a building, seismic sensors have been used, typically located in three mutually orthogonal axes. Previous 36 systems perform Fourier transforms of the sensed 37 vibrations from the sensors to obtain a spectrum ~ 3 ~
01 analysis of the sensed vibrations. ~ecause Fourier 02 analyses are performed, which takes many digital 03 computing hours, the recorded data slgnals were 04 recorded and transported to a laboratory for analysis.
05 Clearly if damaging blasts were created, 06 the blasting personnel would have no knowledge of this 07 until many hours or a day or more following the 08 blasts, due to the required computing time. By this 09 time the blasts could have produced great damage in adjacent structures. The alternative would be to wait 11 until each blast had been analyzed. This would take 12 excessive amounts of time, and would not allow the 13 blasting to be completed within a reasonable interval, 14 slowing the work and substantially increasing the costs.
16 While a spectrum analysis is provided as a 17 result of the Fourier analysis, the data can vary 18 depending on the frequency channel widths in which the 19 data are gathered. ~hus different equipment, having different channel widths or different center 21 frequencies, or with slight differences in ad]ustment, 22 would produce different results. Accordingly there 23 could be no legally reliable measurement results, and 24 the results are clearly subject to abuse.
In addition, the prior art systems, while 26 producing a Fourier analysis, did not provide a result 27 relating to the particle displacement. Thus it was 28 impossible to know whether the aforenoted 0.008 29 particle displacement below 40 Hz or 0.030 in. below 4 Hz was met.
31 Clearly prior art systems for attempting 32 to determine and record seismic energy transmission 33 from a blast were neither practical nor accurate in 34 the field.
The present invention is a blast recorder 36 which determines on a virtually real time basis 37 whether the recommendations of both maximum particle 1 3 ~ 5~
01 velocity and displacement are met. E'urther, the 02 invention apparatus can be produced 50 light and 03 portable that it can be used in the field. Thus the 04 characteristics of the seismic energy can be 05 determined and recorded as proof oE the blast, 06 immediately following a blast. If the blast energy 07 exeeds the recommended values of particle velocity and 08 particle displacement, corrective action can be taken 09 immediately, th~reby avoiding additive damage to nearby buildings.
11 In accordance with a preferred embodiment, 12 the blast recorder is comprised of apparatus for 13 sensing seismic vibrations of a blast, and for 14 providing a velocity signal corresponding to the particle velocity relating to the vibrations. The 16 apparatus for sensing seismic vibrations are 17 preferably sensors. However the sensors can be lS accelerometers followed by integrators, or 19 displacement sensors followed by differentiators, for outputting a velocity signal corresponding to the 21 particle velocity relating to the vibrations. Filters 22 filter each velocity signal into a high and a low 23 frequency band. The velocity signal of each band is 24 then integrated in integrators to determined high and low band displacement signals. The maximum velocity 26 signal in each band is determined, and one or all of 27 the maximum velocity signal determined in the high 28 frequency band, the displacement signal related to the 29 high frequency band, the maximum velocity signal determined in the low frequency band, and the 31 displacement signal related to the low frequency band, 32 are displayed. Preferably the last-noted signals are 33 displayed graphically by printing on a callibrated 34 graph on a printer, but can alternatively or additionally be displayed on a graphical display 36 (e.g. liquid crystal) and numeri.cally either on the 37 instrument display or printer. The signals can also 38 - 3 ~
01 be stored in a local rnemory for more detailed later 02 analyses. Preferably the graphical display is in 03 exactly the form given by the U.S. Bureau of Mines, 04 and is displayed on the same display as the 05 recommended values. In the case that the sensors are 06 accelerometers followed by integrators or displacement 07 sensors followed by differentiators, the filtering can 08 be effected either prior or following integration or 09 differentiation. Further all or some of the signal processing can be done in a microprocessor. If 11 desired, the output signals of the sensors can be 12 recorded for later processing or analysis.
13 A better understanding of the invention 14 will be obtained by reference to the detailed description below, with reference to the following 16 drawings, in which:
17 Figure 1 is a graph representing the 18 maximum safe particle velocities and particle 19 displacements are various frequencies from 1 to 100 Hz, 21 Figure 2 is a reproduction of Figure 1, on 22 which are plotted various curves showing the results 23 of prior art and the present system, 24 Figure 3 is a block schematic of the 25 preferred embodiment of the present invention, and 26 Figures 4-7 are block schematics of other 27 embodiments of the invention.
28 Turning to Figure 1, a graph of maximum 29 safe particle velocity against frequency is shown.
The graph shows that the maximum safe peak particle 31 velocity above 40 Hz is 2.0 in/sec., shown by curve 32 portion A. Below 40 Hz the maximum safe velocity 33 decreases at a rate equivalent to a constant peak 34 displacement of 0.008 in., shown by graph portion B.
Below 15 Hz, the maximum recommended peak particle 36 velocity is .75 in/sec. ~or drywall (curve C), and 37 0.50 in/sec. for plaster (shown as curve portion D).
38 _ ~ _ ~ 3 ~
01 Below about 4 H~. the particle displacement above 02 0.030 in. is considered to be dangerous, this curve 03 portion being designated as E. The graph is speciEic 04 in form, but the safe maxima and slopes are variable, 05 depending on the building struc-ture and location, and 06 thus on its sensitivity.
07 Figure 2 is a reproduction of the 08 aforenoted curve. However in this case a curve F has 09 been superimposed, representing the actual particle velocity with frequency occurring as a result of a 11 blast.
12 As noted earlier, prior art systems 13 perform a spectrum analysis of the particle velocities 14 across the entire frequency spectrum. In performing such analyses, integrations of the particle velocities 16 within successive defined very narrow frequency bands 17 centered at e.g. frequency G, and having bandwidths BW
18 are performed, after recording the seismic signal from 19 each sensor. Within each BW segment, the energy is totalled, and a plot or listing of the values is made, 21 in an attempt to reproduce curve F.
22 As noted earlier, such a procedure takes 23 hours and also involves the use of a large capacity 24 computer. Furthermore, this system does not provide any indication of the displacement, as a requirement 26 in curve graph sections B and E (Figure 1), and thus 27 omits a significant determination of whether the 28 safety limits have been exceeded.
29 In addition, the interpretation of a curve such as a curve F, and how it relates to a curve such 31 as that shown in Figure 1 cannot be done by relatively 32 unskilled field personnel, especially since parts of 33 curve F bear no relationship to the units of curve 34 portions B and E.
In the present invention an output display 36 can be created which corresponds both to the form and 37 to the units of the safe criteria maxima prescribed by 1 3 ~
01 the U.S. Bureau of Mines. The output display of the 02 present inven-tion is shown in Figure 2, which shows 03 the results of the blast in representative curve 04 sections A' corresponding to curve portion A, B' 05 corresponding to curve portion B, C' corresponding to 06 curve portion C or D, and curve portlon E' 07 corresponding to curve portion E.
08 The above result is obtained in the 09 present invention by filtering the sensor output signal as it is received, splitting it into a high 11 band signal preferably above about 15 Hz, and a low 12 band signal, below about 15 Hz.
13 In the preferred embodiment, received 14 velocity sensor ou-tput signals in the high band and low frequency bands are integrated, resulting in 16 displacement signals. The peak velocity signal in 17 each of the respective bands i5 printed, displayed or 18 plotted as curve portions A' and C' respectively, and 19 are merely horizontal lines at the peaks conforming to the form of curve portions A and C. The displacement 21 signals for the high and low frquency bands are 22 printed, displayed or plotted as curve portions B' and 23 E'.
24 The curve portions A', B', C' and E' are preferably presented on a CRT or LED display with a 26 curve representing the allowable maxima, that is curve 27 portions A, B, C and/or D and E. Thus for a 28 particular blast the curve 1, representing the 29 allowable maxima, and curve 2, representing the results of a particular blast, are displayed 31 together. An unskilled worker can thus immediately 32 determine whether a particular blast exceeds the 33 allowable maxima of either or both particle velocity 34 or particle displacement. Further, since the determination is made in real time, there is no delay 36 involved in adjusting the blast parameters, as was 37 required in the prior art.
~ 3 ~
01 Figure 3 illustrates the preferred 02 embodiment of the presen-t invention. A representative 03 seismic sensor 3 provides an output velocity signal to 04 low and high pass filters 4 and 5. Preferably three 05 separate sensors in three mutually orthogonal axes are 06 used for sensing seismic energy in three mutually 07 orthogonal directions. Preferably t.he output signal 08 of each sensor is treated separately, but the vactor 09 sum of all three sensors could be used in certain cases. The resulting output signal of each sensor is 11 applied to low and high pass filters 4 and 5. The low 1~ pass filter passes all input signals below about 13 1~ Hz, while the high pass filter passes signals above 14 about 15 Hz. However the particular bands used can be different from the above to suit the circumstances.
16 The output signals of low and high pass 17 filters 4 and 5 are applied to analog to digital 18 converter 6. The output signal of low pass filter 4 19 is also applied to integrator 7, and the output signal of high pass filter 5 is applied to integrator 8. The 21 output signals of integrators 7 and 8, representing 22 displacements, are applied to the analog to digital 23 converter 6, along with the output signals of low and 24 high pass filters 4 and 5 which represent the velocity.
26 ~nalog to digital converter 6 converts the 27 four singals input to it into a digital form for 28 application to a central processing unit 9 to which is 29 connected a memory 10, a display 11, and a keypad 12.
The display is representative of one or more of 31 several forms of displays, such as an LCD graphical 32 display, which may or may not include an alphanumeric 33 display of the values displayed, andlor a printer, for 34 providing hard copy of the displayed data.
Memory 10 is used by the CPU 9 to store 36 operation programs, and also to store the data to be 37 displayed, in a well known manner.
1 3 ~
01 The channels each comprised of the low 02 pass Eilter, integrator and connection from the low 03 pass ~ilter to A/D converter 6 are preferably 04 reproduced for each mutually or-thogonal seis~ic 05 sensor, and the vector sum of the signals from the A/D
06 converter determined by the CPU 9. Alternatively the 07 sensor 3 outputs a vector sum of the energy received 08 and provides a signal into the circuit shown.
09 It should also be noted that the vector summation, low pass filtering and in-tegration can be 11 performed by the CPU itself. In that case Figure 3 12 should be considered as a representative block diagram 13 illustrating the algorithm to be perEormed in 14 obtaining the signal forms required by the CPU in order to form the display of the graph 2 shown in 1~ Figure 2, except that analog to digital conversion can 17 be performed with the output signals of the sensors, 18 prior to filtering, rather than following, as shown.
19 The signals representative of the constants in the various portions of graph 1 also to be displayed in 21 display 11 can be prestored in memory 10 by entering 22 them by means of keypad 12 connected to CPU 9.
23 Thus in operation the entire apparatus, 24 preferably packaged in a suitcase sized instrument is taken to the field, and the sensor unit compxised of 26 seismic sensors in three mutually orthogonal axes is 27 placed where it can sense the ground vibrations. The 28 blast is set off. The resulting signal from each 29 sensor 3 is applied to corresponding low and high pass filters 4 and 5, and split into high and low frequency 31 bands. The output signals of low and high pass 32 filters 4 and 5 are applied to A/D converter 6, and 33 are also applied to integrators 7 and 8. The 34 integrated output signals of integrators 7 and 8 are also applied to A/D converter 6. The digitized 36 resulting output signals are applied to CPU 9.
37 In CPU 9 in conjunction with memory 10, 3~ - 8 -~ 3 ~
01 the digitally converted signals are vector summed, and 02 a determination is made of the peak energy during the 03 blast interval in the hlgh frequency band, e.~. a~ove 04 15 Hz, and the peak energy in the low frequency band, 05 e.g. below 15 Hz. These peak energies are displayed 06 or plotted as horizontal lines A' and C' respectively.
07 The energies in each of the high and low 08 bands is summed, and integra-ted, to obtain peak 09 displacements in the low and high frequency bands during the blast, which are plot-ted as the sloped ll lines E' and B' respectively on the same display, the 12 slope of the lines E and B being the integrals of the 13 energy in each of the bands. Where the lines B' and 14 C' intersect, they are terminated, and where the lines E' and C', and B' and A' intersect, they are 16 terminated, to form a continuous plot.
17 As noted earlier, the values representing 18 the line segments representing the particle velocity 19 and displacement danger maxima are prestored in memory. These are displayed on display ll as line 21 segments A, B, C and E at the same time as line 22 segments A', B', C' and E'.
23 The result is an easy to read display 24 which corresponds substantially to the curve form representing the particle velocity and displacement 26 values recommended by the U.S. Bureau of Mines, and 27 are readily understandable by an unskilled worker in 28 the field.
29 In addition, the display is made available immediately after the blast, avoiding the requirement 31 for laboratory analyses of the seismic data to 32 determine whether the blast criteria have been 33 exceeded. Yet if desired, the sensor output signals 34 can be recorded, and carried to a laboratory for later analysis if desired, whereupon the recorded signals 36 are input into the apparatus as sensor signals.
37 In accordance with other embodiments, as 38 _ 9 _ .
~3~5~
01 shown in Figure 4, -the ~ensor 3A is an accelerometer 02 13, feeding an acceleration signal into an inteyrator, 03 which outputs a velocity signal to low and high pass 04 filters 4 and 5 as in Figure 3. The remainder of this 05 embodiment is as in Figure 3.
06 As shown in Figure 5, the sensor is a 07 displacement sensor, Eeeding a displacement signal 08 into a differentiator, which outputs a velocity signal 09 to low and high pass filters 4 and 5 as in Figure 3.
The remainder of this embodiment is as in Figure 3.
11 As shown in Figure 6, the sensor is an 12 accelerometor, feeding an acceleration signal into low 13 and high pass filters 7A and 8A, which band limit the 14 signal into the bands such that after integration in integrators 13A and 13B it corresponds to the velocity 16 signal bands output from filters 7 and 8. The signals 17 from the integrators 13A and 13B are fed to 18 integrators 7 and 8 and A/D 6 as in Figure 3, to which 19 the remainder of this embodiment corresponds.
As shown in Figure 7, the sensor is a 21 displacement sensor, feeding a displacement signal 22 into low and high pass filters 7B and 8B, which band 23 limit the signal into the bands such that after 24 diEferentiation in differentiators 14A and 14B, it corresponds to the velocity signal bands output from 26 filters 7 and 8. The signals from differentiators 14A
27 and 14B are fed to integrators 7 and 8 and A/D 6 as in 28 Figure 3, to which the remainder of this embodiment 29 corresponds.
It should also be noted that any of these 31 embodiments can be implemented as an algorithm in a 32 computer, processing the signals received from the 33 various sensors, as described above.
34 The result is a a relatively inexpensive, portable instrument which is highly useful for 36 practitioners in the blasting field, and, i-t is 37 believed, represents a significant advance in the art.
~ 3 ~
01 A person understanding this invention may 02 now conceive of various alternative structures or 03 variations thereof, using the principle described 04 herein. All are considered to be within the sphere 05 and scope of the invention as defined in the claims 06 appended hereto.
Claims (14)
1. A blast recorder comprising:
(a) means for sensing seismic vibrations of a blast, and for providing a velocity signal corresponding to the particle velocity related to said vibrations, (b) means for filtering the velocity signal into high and a low frequency bands, (c) means for integrating over the period of a blast the velocity signal of each band to obtain high and low band displacement signals, (d) means for determining the peak of the velocity signal in each band, over the period of the blast, and (e) means for displaying one or all of the peak of the velocity signal determined in the high frequency band, the displacement signal related to the high frequency band, the peak of the velocity signal determined in the low frequency band, and the displacement signal related to the low frequency band.
(a) means for sensing seismic vibrations of a blast, and for providing a velocity signal corresponding to the particle velocity related to said vibrations, (b) means for filtering the velocity signal into high and a low frequency bands, (c) means for integrating over the period of a blast the velocity signal of each band to obtain high and low band displacement signals, (d) means for determining the peak of the velocity signal in each band, over the period of the blast, and (e) means for displaying one or all of the peak of the velocity signal determined in the high frequency band, the displacement signal related to the high frequency band, the peak of the velocity signal determined in the low frequency band, and the displacement signal related to the low frequency band.
2. A blast recorder as defined in claim 1 in which said means for displaying includes a printer for graphically printing the peak of the velocity signal determined in the high frequency band above a first intermediate frequency in the high frequency band, the displacement signal related to the high frequency band below the first intermediate frequency, the peak of the velocity signal in the low frequency band determined in the low frequency band above a second intermediate frequency in the low frequency band, and the displacement signal related to the low frequency band, as a continuous line.
3. A blast recorder comprising:
(a) means for sensing seismic vibrations of a blast, and for providing a velocity signal corresponding to the particle velocity related to said vibrations, (b) means for integrating the velocity signal to obtain a displacement signal, (c) means for determining the peak of the velocity signal over the period of the blast, and (d) means for displaying the peak of the velocity signal and the displacement signal as representatives of the peak particle characteristics of the blast.
(a) means for sensing seismic vibrations of a blast, and for providing a velocity signal corresponding to the particle velocity related to said vibrations, (b) means for integrating the velocity signal to obtain a displacement signal, (c) means for determining the peak of the velocity signal over the period of the blast, and (d) means for displaying the peak of the velocity signal and the displacement signal as representatives of the peak particle characteristics of the blast.
4. A method of displaying seismic blast signals comprising:
(a) receiving a seismic particle velocity signal resulting from a blast, (b) integrating the particle velocity signal over the period of the blast to obtain a particle displacement signal, (c) determining the peak of the velocity signal, (d) displaying the peak velocity signal and the particle displacement signal as the blast criteria maxima.
(a) receiving a seismic particle velocity signal resulting from a blast, (b) integrating the particle velocity signal over the period of the blast to obtain a particle displacement signal, (c) determining the peak of the velocity signal, (d) displaying the peak velocity signal and the particle displacement signal as the blast criteria maxima.
5. A method as defined in claim 4 including the step of splitting the seismic signal into low and high band components prior to the integrating step, and separately integrating the low and high band components, determining the peaks of the high and low band components of the velocity signal, and displaying said peaks and the integrated high and low band components as peak particle velocity and particle displacement values within the respective high and low frequency bands.
6. A method as defined in claim 5 including the step of displaying the high and low band component peak particle velocities as horizontal lines and the particle displacement values as sloped lines on a graphical display, as a continuous line.
7. A method as defined in claim 6 including the step of also displaying the peak safe recommended particle velocities as horizontal lines and peak safe recommended particle displacement as sloped lines, as a continuous, line, on said display.
8. A method as defined in claim 4, 5, 6 or 7 in which the display is a printer.
9. A method as defined in claim 4, 5 or 6 including the step of vector summing the seismic signal from several seismic sensors to obtain said seismic particle velocity signal.
10. A method of displaying seismic blast signals comprising:
(a) receiving seismic energy signals from a blast sensor, (b) processing the energy signals to obtain velocity signals relating to said blast, (c) filtering either the energy signals prior to, or the velocity signals following said processing step, into high and low frequency bands, to obtain high and low band velocity signals, (d) integrating over the period of the blast the high and low band velocity signals to obtain high and low band displacement signals, (e) determining the peak velocity signal in each band, over the period of the blast, and (f) displaying one or all of the peak of the velocity signal determined in the high frequency band, the peak of the velocity signal determined in the low frequency band, and the displacement signal related to the low frequency band.
(a) receiving seismic energy signals from a blast sensor, (b) processing the energy signals to obtain velocity signals relating to said blast, (c) filtering either the energy signals prior to, or the velocity signals following said processing step, into high and low frequency bands, to obtain high and low band velocity signals, (d) integrating over the period of the blast the high and low band velocity signals to obtain high and low band displacement signals, (e) determining the peak velocity signal in each band, over the period of the blast, and (f) displaying one or all of the peak of the velocity signal determined in the high frequency band, the peak of the velocity signal determined in the low frequency band, and the displacement signal related to the low frequency band.
11. A method as defined in claim 10 in which the seismic energy signals are comprised of acceleration signals, and the processing step is comprised of integration.
12. A method as defined in claim 10 in which the seismic energy signals are comprised of displacement signals, and the processing step is comprised of differentiation.
13. A method as defined in claim 10, 11 or 12 in which the signals are received directly from a seismic sensor during the period of a blast.
14. A method as defined in claim 10, 11 or 12 in which the signals are received from a recording of seismic energy signals recorded some time previously.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000569428A CA1315868C (en) | 1988-05-30 | 1988-05-30 | Blast recorder and method of displaying blast energy |
| US07/352,053 US4935748A (en) | 1988-05-30 | 1989-05-15 | Blast recorder and method of displaying blast energy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000569428A CA1315868C (en) | 1988-05-30 | 1988-05-30 | Blast recorder and method of displaying blast energy |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1315868C true CA1315868C (en) | 1993-04-06 |
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ID=4138201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000569428A Expired - Fee Related CA1315868C (en) | 1988-05-30 | 1988-05-30 | Blast recorder and method of displaying blast energy |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4935748A (en) |
| CA (1) | CA1315868C (en) |
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| ATE315219T1 (en) * | 1999-05-19 | 2006-02-15 | Vibro Meter Ag | METHOD AND ARRANGEMENT FOR COMBINED VIBRATION MEASUREMENT |
| DE10024394C5 (en) * | 2000-05-17 | 2008-11-06 | Siemens Ag | Determination method for an actual speed of a movable displacement element |
| US6654315B1 (en) * | 2002-06-05 | 2003-11-25 | The United States Of America As Represented By The Secretary Of The Navy | Sonar display system and method |
| KR100580643B1 (en) * | 2004-02-10 | 2006-05-16 | 삼성전자주식회사 | Appratuses and methods for detecting and discriminating acoustical impact |
| DE102004008225B4 (en) * | 2004-02-19 | 2006-02-16 | Infineon Technologies Ag | Method and device for determining feature vectors from a signal for pattern recognition, method and device for pattern recognition and computer-readable storage media |
| US7566270B2 (en) * | 2004-04-29 | 2009-07-28 | Cfph, Llc | System and method for wagering based on multiple financial market indicators |
| US7637807B2 (en) | 2004-04-29 | 2009-12-29 | Cfph, L.L.C. | System and method for mapping results from sporting events to game inputs |
| US20050245308A1 (en) * | 2004-04-29 | 2005-11-03 | Cfph, Llc | System and method for wagering based on financial market indicators |
| US10332332B2 (en) * | 2007-12-21 | 2019-06-25 | Cfph, Llc | System and method for slot machine game associated with financial market indicators |
| US8460085B2 (en) | 2007-12-21 | 2013-06-11 | Cfph, Llc | System and method for providing a roulette game based on financial market indicators |
| US8535140B2 (en) | 2007-12-21 | 2013-09-17 | Cfph, Llc | System and method for providing a baccarat game based on financial market indicators |
| US8758108B2 (en) * | 2007-12-21 | 2014-06-24 | Cfph, Llc | System and method for slot machine game associated with market line wagers |
| US11257330B2 (en) | 2008-02-15 | 2022-02-22 | Cfph, Llc | System and method for providing a baccarat game based on financial market indicators |
| WO2014047714A1 (en) | 2012-09-26 | 2014-04-03 | Vibrosystm Inc. | System and method for vibration severity assessment independently of vibration frequency |
| US9791336B2 (en) | 2014-02-13 | 2017-10-17 | Evigia Systems, Inc. | System and method for head acceleration measurement in helmeted activities |
| CN104154990A (en) * | 2014-08-12 | 2014-11-19 | 武汉长江仪器自动化研究所有限公司 | Integrated blasting recorder and working method thereof |
| CN106772574B (en) * | 2016-11-28 | 2019-02-15 | 中国石油天然气集团有限公司 | A kind of spectrum continuation method keeping low-frequency information |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4571710A (en) * | 1982-08-31 | 1986-02-18 | Neidell Norman S | Seismic method for identifying low velocity subsurface zones |
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1988
- 1988-05-30 CA CA000569428A patent/CA1315868C/en not_active Expired - Fee Related
-
1989
- 1989-05-15 US US07/352,053 patent/US4935748A/en not_active Expired - Fee Related
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| US4935748A (en) | 1990-06-19 |
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