JP6998014B2 - Blasting method - Google Patents

Description

The present invention relates to a blasting method in which blasting is performed using an ignition device that ignites at a set ignition timing.

The electronic delay type electric detonator is an ignition device that can set the timing of igniting the explosive in milliseconds. For this reason, the electronic delay type electric detonator is used for applications that require a simultaneous effect such as smooth blasting (a construction method that destroys only the part to be destroyed), and the explosion is divided into multiple stages to suppress vibration and noise peaks. It is used in applications where the required accuracy of explosive ignition is severe. Here, the simultaneousness means that two or more holes are detonated at the same time.

If the optimum timing and second time interval (timetable) for igniting the electronic delay type electric detonator can be designed, it can be faithfully reproduced in that timetable, so it is resistant to vibration and noise. It is known that it exerts an excellent inhibitory effect. Therefore, a method for designing an optimum timetable has been proposed (see, for example, Patent Documents 1 and 2).

The vibration and noise propagation characteristics that are required when designing the optimum timetable for each maintenance target such as private houses and public facilities are that the blast point moves as the tunnel is dug, and the positional relationship with the maintenance target. Therefore, the propagation path and the geology on that path are different, and one cannot be determined. The propagation characteristic refers to the one that specifies the dominant frequency of vibration and noise propagated to the maintenance target. The dominant frequency is the frequency with the largest amplitude (peak frequency). Further, in the conventional electronic delay type detonator, the ignition timing can be set only at the manufacturing factory, so that it is difficult in the process to change the setting according to the request at the site.

However, in recent years, an electronically delayed electric detonator that can set the ignition timing in the field has appeared (see, for example, Non-Patent Document 1).

In response to this, a technique has been proposed in which the propagation characteristics are remeasured for each maintenance target and fed back to the timetable as the tunnel is dug so that the existing timetable can be reviewed at an appropriate time (for example). , Patent Document 3).

Republished No. 98/21544 Japanese Unexamined Patent Publication No. 1-2858800 JP-A-2015-137788

"High-precision electronic detonator" eDev "series", [online], December 25, 2014, Ministry of Land, Infrastructure, Transport and Tourism, [Search on September 5, 2016], Internet <URL: http: // www. netis.mlit.go.jp/NetisRev/Search/NtDetail6.asp?REG_NO=KT-140090&TabType=2&nt=nt>

However, in the technique described in Patent Document 3, since the timetable is reviewed regardless of whether it is necessary or not, the amount of work increases and the construction period becomes long. This is a factor of high cost and is not satisfactory as a management method in the field.

The present invention has been made in view of the above problems, and is a method of blasting using an ignition device that ignites at a set ignition timing. The process of measuring the vibration generated by rupture at a predetermined point, the process of extracting the propagation characteristics of the vibration propagated to the predetermined point from the measurement results, and the step of changing the set ignition timing based on the extracted propagation characteristics. The blasting method is provided, which includes a step of determining whether or not to perform the ignition, and a step of changing the ignition timing setting so as to reduce the vibration at a predetermined point when the determination is made.

According to the present invention, it is possible to provide a blasting method capable of reducing the amount of work and shortening the construction period while suppressing vibration and noise.

The figure explaining the excavation and maintenance target of a tunnel. The figure explaining that vibration can be suppressed by changing a second time interval. A flowchart illustrating the work flow of the blasting method. The figure explaining the blasting pattern. The figure which illustrated the position of the explosive and the detonator installed in the charge hole. The figure which exemplifies the vibration result measured in the maintenance target. The figure which showed the waveform (time history characteristic) and the frequency characteristic of the 5th stage vibration in FIG. The figure which showed the waveform (time history characteristic) and the frequency characteristic of the 7th stage vibration in FIG. The figure which used the waveform shown in FIG. 8 as a representative waveform, and showed the vibration level of the vibration predicted when it oscillated by the designed timetable. The figure which made the prediction using the second time interval as a parameter, and illustrated the relationship between the second time interval and the maximum velocity and the maximum vibration level. The waveform shown in FIG. 8 is used as a representative waveform, and is a diagram showing a vibration waveform (time history characteristic) and a frequency characteristic predicted when vibrated by a designed timetable. The figure which illustrated the hardware configuration of an information processing apparatus. A conceptual diagram showing that the amplitude can be reduced by superimposing vibration waveforms at intervals of seconds that are in opposite phase.

Before explaining the blasting method of the present invention, the excavation and maintenance target of the tunnel by blasting will be described with reference to FIG. Blasting is the work of crushing rocks using the explosive power of explosives, and is also used when conducting geological surveys by vibrating the ground. In the excavation of the tunnel 12 by blasting in the ground 10 or the like, a hole (charged hole) for charging the explosive is formed in the face 11 to be blasted by using a rock drill such as a drill jumbo. , It is carried out by charging an explosive in the charge hole and igniting (blasting) with a detonator as an ignition device.

The position and number of charge holes, the amount of explosive to be charged, the order and time interval of detonation, etc. are determined by the geology, the shape and size of the cross section of the tunnel 12, the scattering of debris to the surroundings, vibration and noise, etc. Considering this, it is designed as an ignition timetable (also simply called a timetable) required to set an appropriate blasting pattern and optimum ignition timing. The timetable is information indicating in what order and at what time interval each charge hole or each charge hole group is ignited.

A detonator is a pyrotechnic that contains an explosive that ignites with a small amount of heat or impact, and includes an igniter, a detonator, and an adjunct. As a detonator, an electrode is embedded in the igniter, and when an electric current is passed through the electrode, the igniter is ignited. An electric detonator that explodes the drug can be used. Among the electric detonators, an electronic delay type electric detonator that further includes a capacitor and an electronic timer and can set the ignition timing in milliseconds can be used.

Since the electronic delay type electric detonator can set the ignition timing, it is used for the purpose of intentionally dividing the blast into multiple parts and suppressing the peak of vibration and noise, and it is generated from each charge hole. It is considered to be used for the purpose of suppressing the maximum amplitude by dispersing vibration and noise so that they do not overlap at a short moment, and for obtaining the timing of canceling each other's amplitudes due to the phase difference of the waves during dispersion. ..

For example, a single burst is performed once, then a single burst is performed with a time interval (second time interval) of 3 milliseconds (ms), and the results of measuring the vibrations are superimposed, as shown in FIG. 2 (a). The waveform becomes like this. Single-shot blasting is a method of blasting one shot at a time. Here, the vibration is measured as the velocity with respect to the elapsed time. The waveform of the first blasting and the waveform of the second blasting are similar only in phase. At a short second time interval of 3 ms, the amplitude of the waveform obtained by synthesizing the waveform of the first stage and the waveform of the second stage is large.

When the single blasting is performed once, then the single blasting is performed with a long time interval of 12 ms, and the measurement results of the vibrations are superimposed, the waveform as shown in FIG. 2 (b) is obtained. In this case as well, the first and second waveforms have the same waveform except that only the phase is different. However, the waveform obtained by synthesizing the first and second waveforms is smaller than the amplitude of the waveform of each stage.

If the reproducibility of the waveform properties of single blasting is high in this way, it can be seen that the amplitude, which is the maximum velocity, changes greatly depending on how the vibration waveforms are overlapped, that is, the second time interval. For this reason, in the design of the timetable, the optimum second time interval such as reducing this amplitude is set.

However, the propagation characteristics of vibration and sound (noise) that propagate to a predetermined point, that is, the conservation target, which is the premise of designing the timetable, are such that the explosion point moves daily as the tunnel is dug, and the propagation route to the conservation target. And because of the difference in geology on the route, it is not fixed to one. This is because the distance between the blast point and the conservation target changes, and the geology between them is not constant. Here, the propagation characteristics specify the highest frequency (dominant frequency) of the vibration and noise propagated to the conservation target, and the conservation target is a person's house or public facility that may be damaged by the influence of vibration or noise. , Agricultural land, etc. In FIG. 1, houses 13 and 14 are shown as conservation targets.

Since the ignition timing of the electronic delay type electric detonator is set at the manufacturing plant, even if the optimum timetable is designed based on the propagation characteristics at a certain excavation point, it cannot be reflected. Even if it deviates from the reality, it is often necessary to use a detonator with an ignition timing set at the manufacturing plant. In this case, even if an electronic delay type electric detonator is used, the desired vibration and noise suppression effect cannot be obtained.

In view of this, in recent years, an electronic delay type electric detonator of a type that can set the ignition timing in the field has appeared. By using this type of electronic delay type electric detonator, it is possible to design the optimum timetable at the site and set the ignition timing to reflect it, and obtain the desired vibration and noise suppression effect in blasting excavation. be able to. The construction method of the present invention is a blasting construction method premised on the use of this type of electronic delay type electric detonator. Hereinafter, this type of electronic delay type electric detonator will be simply referred to as a detonator. Since noise such as noise is generated by vibration of air or a solid object and can be considered in the same manner as vibration propagating to the ground, only the vibration propagating to the ground will be described here.

The outline of the blasting method of the present invention will be described with reference to FIG. This blasting method starts from step 300, and in step 305, a part of the face 11 such as test blasting is blasted or a part of the face is hit in order to obtain the propagation characteristics (predominant frequency) for each maintenance target. The face 11 is blasted by giving. In blasting, the worker first determines the position of the charge hole according to the designed blast pattern, and drills the hole with a rock drill to form the charge hole. Then, an explosive is charged into some of the formed charge holes, a detonator is installed, and the detonator and the blaster are connected by an ignition cord. After that, the worker presses the ignition switch of the blaster to explode the explosive charged in the charge hole.

The impact on the face 11 can be given by a machine called a breaker used to shape the tunnel, for example in tunnel excavation. Here, an example of a method of vibrating the face 11 in order to obtain the dominant frequency for each maintenance target has been given, but the method is not limited to these methods as long as the dominant frequency for each maintenance target can be obtained.

In step 310, vibration propagating in the ground is measured at a predetermined point, such as houses 13 and 14, which are to be maintained. The measured vibration result is input to an information processing device described later. In step 315, the information processing apparatus extracts propagation characteristics such as the dominant frequency based on the measured vibration. Then, in step 320, a timetable is designed based on the extracted propagation characteristics , and the second time interval of each detonator is set.

In step 325, a charge hole is formed, an explosive with a detonator attached to the charge hole is charged, and the explosive is detonated at a set time interval to perform the main blasting, and the tunnel 12 is excavated. Since the detonation is performed at the set optimum timing, the vibration suppression effect expected in the maintenance target can be obtained. After blasting, crushed stones and other debris generated by blasting are carried out of the tunnel.

Carrying out the scraps is called scraping, and it is done using a shaf loder, a dump truck, or the like. The chafloda is a machine that loads the scraps onto the dump truck by scraping the scraps with the bucket in front, moving the scraps loaded on the belt conveyor to the rear, and dropping them onto the dump truck.

In step 330, the vibration generated by the main blasting is measured in the maintenance target. Then, in step 335, the propagation characteristics such as the dominant frequency are extracted by the information processing apparatus based on the measurement result of the main blasting, and the propagation characteristics are grasped. In step 340, it is determined whether or not to continue this blasting method. For example, it is possible to determine whether or not to continue this blasting method depending on whether or not it is possible to respond by reviewing the timetable without major changes in geology. If it does not continue, the process proceeds to step 360 to end the blasting excavation by this blasting method. On the other hand, if the blasting method is to be continued, the process proceeds to step 345.

In step 345, it is determined whether or not the designed timetable needs to be reviewed based on the propagation characteristics extracted in step 335. If necessary, proceed to step 350 and review the timetable based on the measured propagation characteristics. In step 355, the second time interval of each detonator is reset based on the reviewed timetable, and the process returns to step 325. On the other hand, if it is not necessary, the seconds and time intervals already set may be sufficient, so the process directly returns to step 325.

By repeating the main blasting in step 325, the tunnel 12 can be excavated. In addition, every time this blast is performed, the above-mentioned breaker can be used to remove the protruding parts and floating stones into the tunnel pit, and the shape of the tunnel can be adjusted. In addition, to prevent the ground around the excavated tunnel from collapsing, a steel frame (support work) that matches the shape of the tunnel is built, cement is sprayed, and reinforcing bars (lock bolts) are driven in. , Can be lining. Furthermore, a sheet can be attached to prevent water from the ground or the like from entering the tunnel, and concrete can be placed on the surface of the tunnel using a machine called a centle to finish the tunnel.

In the present invention, it is determined whether or not the timetable needs to be reviewed, and the timetable is reviewed only when necessary. Therefore, it is possible to reduce the amount of work and shorten the construction period while reducing the vibration.

The overall outline of the blasting method of the present invention is as described above, but each detailed process will be described below. With reference to FIG. 4, the position of the charge hole formed in the face 11 shown in FIG. 1 will be described. These charge holes are holes formed during the main blasting in step 325 of FIG. A plurality of charge holes 15 are formed in the face 11. The charge hole 15 can be formed by using the above-mentioned rock drill. The plurality of charge holes 15 form a plurality of charge hole groups A1 to A15 for performing stage blasting. Stage blasting is a method of blasting several shots in sequence.

The charge hole group A1 at the center of the face 11 is for core removal. Core removal is the process of first exploding to form a fragile free surface. The free surface is the surface on which crushed stones and the like generated by blasting are extruded. After the core is removed, the charge hole groups A2, A3, ... Are blasted in this order so as to expand the space toward the outer peripheral side thereof. The blasting pattern shown in FIG. 4 is an example, and the number and arrangement pattern of each charge hole can be appropriately changed. In addition, the number of stages and the arrangement for performing stage blasting may be determined by any method known so far.

The arrangement of the explosive and the detonator in the charge hole will be described with reference to FIG. In each charge hole 15, there are a plurality of explosives (so-called parent die and increase die) 20, a detonator 21 provided in the explosive (parent die) 20 on the back side of the charge hole 15, and an opening side of the explosive 20. A filling 22 such as clay for closing each charge hole 15 is provided. The lead wire 23 from the detonator 21 is connected to the blaster 24 equipped with an ignition switch through the filling 22.

The detonator 21 is a detonator in which the second time interval can be set in 1 ms units, and the second time interval can be arbitrarily set and changed at the site. A device called a checker 25 or the like including an information processing device described later is used for setting the second time interval of the detonator 21. The checker 25 can confirm and set the second time interval, as well as confirm whether the detonator 21 functions properly. Further, a connection counter 26, a resistance measuring device, or the like can be used to measure the electric resistance or the like after connecting the conducting wire 23 and confirm the number of connections.

Next, a method of extracting the propagation characteristics for each maintenance target from the vibration of the face 11 in steps 305 to 315 of FIG. 3 will be described. The propagation characteristics of each maintenance target can be extracted from the results of vibrations measured at the maintenance target by vibrating at the blasting point to generate vibrations. In order to measure the vibration, a vibration meter that measures the displacement speed and the displacement acceleration due to the vibration propagating to the maintenance target can be used. Incidentally, in the case of noise, a sound level meter that measures the sound pressure can be used.

As one method of generating vibration at the blasting point, the method of performing the test blasting described briefly above can be mentioned. Specifically, it is a method of performing one-shot blasting with the face 11. For example, set a second time interval of 300 ms or more in the detonator 21 so that the main part of the vibration from each hole does not overlap with about 6 to 10 holes that are only part of the blasting target, for example, only core removal, and 1 hole. Explode on a trial basis in the first stage.

FIG. 6 shows a total of 10 stages by adding 4 holes (4 stages) for auxiliary core removal to 6 holes (6 stages) for core removal, and measured with a virtual maintenance target with a second time interval of 300 ms. It is a figure which exemplifies the relationship between the elapsed time and the velocity (kine). kine is a unit representing the amount of displacement that is displaced in 1 second, and 1 kine is 1 cm / s. This speed may be the displacement speed measured by the above-mentioned speedometer, or may be calculated by integrating the acceleration measured by the above-mentioned accelerometer with time.

The fact that the main parts of the vibration do not overlap means that, as shown in FIG. 6, the waveforms of the main parts representing the vibrations of each stage are spaced so as not to overlap each other. In FIG. 6, by setting the second time interval to 300 ms, it is possible to distinguish the waveform of the main part of each stage. It should be noted that the waveform of each stage is largely displaced when it blasts once, gradually becomes smaller, and then the displacement continues although it is small. For this reason, the portion that has a characteristic and is greatly displaced is set as the main portion, and the second time interval is set based on the waveform of the main portion. The waveforms of the 4th and 8th stages hardly appeared, but it is presumed that the rocks and the like were not destroyed well by the blast and the vibration was not transmitted well to the conservation target.

FIG. 6 shows vibrations in three directions (X-axis, Y-axis, and Z-axis), and the waveform of the main part of each stage when blasting at 300 ms intervals has the largest amplitude. is doing. As for the three directions, for example, the direction parallel to the plane of the face 11 may be the X axis, the excavation direction may be the Y axis, and the vertical direction may be the Z axis. In this example, the 5th and 7th stages are larger than the other stages. Further, the maximum value (peak) of the amplitude is larger in the 5th and 7th stages than in the other stages. A large peak means that the S / N ratio, which is the ratio of the signal to the noise actually desired, is high, and it means that good results can be obtained when setting the second time interval. ..

FIG. 7A is a diagram showing the elapsed time of the waveform in the fifth stage changed, and FIG. 8A is a diagram showing the elapsed time of the waveform in the seventh stage changed. .. The waveform representing the relationship between the elapsed time and the speed is called a time history characteristic. By Fourier transforming this time history characteristic, it is possible to obtain a frequency characteristic that represents the relationship between the frequency (Hz) and the acceleration Fourier spectrum (m / s ² ). The Fourier transform is a well-known method for decomposing an arbitrary waveform into each frequency component and determining its magnitude (amplitude) and its position (phase), and is not described in detail here.

FIG. 7B is a diagram showing the frequency characteristics of the fifth stage, and FIG. 8B is a diagram showing the frequency characteristics of the seventh stage. The frequency characteristics shown in FIGS. 7 (b) and 8 (b) have a peak at a specific frequency. These frequency characteristics have a peak at a frequency of about 200 Hz. It is considered that this peak includes those caused by the propagation path, geology, etc. in the predominant frequency caused by blasting. Further, FIGS. 7 (b) and 8 (b) have the same peak frequency and have similar graphs. From this, it is possible to evaluate the propagation characteristics (dominant frequency) of the maintenance target at any of the 5th and 7th stages.

In this way, at least 6 holes can be obtained because the first dominant frequency that can be evaluated by the single-shot blasting of the fifth stage can be obtained and the second dominant frequency that can be evaluated by the single-shot blasting of the seventh stage can be obtained. To some extent, one predominant frequency can be obtained that can evaluate the propagation characteristics of the object to be preserved. Therefore, by preparing at least about 6 holes and performing single blasting on a trial basis, it is possible to extract the desired dominant frequency as the propagation characteristic for each maintenance target, taking into consideration the variation in vibration amplitude. The predominant frequency for this purpose is called the predominant frequency to be preserved.

By obtaining this predominant frequency to be maintained, the optimum timetable can be designed. The method of designing this optimum timetable will be described later.

As another method of generating vibration at the blasting point, there is a method of utilizing the vibration of the breaker work for striking the face 11 to remove the floating stones. A breaker is a machine that hits and drops floating stones, and the number of hits varies depending on the load, but it is 1300 times / min or less. For this reason, a predominant frequency due to impact is generated below 10 Hz for a large circuit breaker and below 20 Hz for a standard circuit breaker.

By measuring the vibration in the maintenance target during the breaker operation, the same time history characteristics as in FIG. 6 can be obtained. Then, this time history characteristic is Fourier transformed to obtain the frequency characteristic. If the dominant frequency other than the frequency caused by the impact can be confirmed from this frequency characteristic, the dominant frequency can be set as the dominant frequency to be maintained. The reason for excluding the frequency caused by the impact in this way is that the frequency caused by the impact is not the predominant frequency caused by the propagation path, geology, or the like.

As yet another method of generating vibration at the blasting point, there is a method of utilizing excavation blasting (step blasting) at the face 11. In this method, three or more charge hole groups (staged series) having different seconds and time intervals are prepared. The seconds and time intervals within the same series are constant. For example, when there are three series of A1 to A3, the second time interval when detonating each charge hole constituting A1 in order is fixed, for example, 5 ms, and A2 is different from A1, for example, 9 ms. , A3 is different from A1 and A2, for example, 15 ms.

As with the test blasting, the series are connected at intervals of 300 ms or more to form a step blasting of the entire face. The reason why the series are connected at intervals of 300 ms or more in this way is to avoid mutual influence between the series.

In this way, step blasting is performed, and at that time, vibration is measured in the maintenance target. Then, the time history characteristics are obtained in the same manner as described above. In addition, the time history characteristics are Fourier transformed to obtain the frequency characteristics, and the dominant frequency is evaluated for each vibration from each series. Since the dominant frequency is generated in each series due to the time interval, if the dominant frequency common to the series other than the dominant frequency can be confirmed, the dominant frequency is set as the dominant frequency to be maintained.

The reason for excluding the dominant frequency due to the second time interval is that it is not the dominant frequency due to the propagation path, geology, etc., as in the case of the above breaker. In addition, the common dominant frequency among the series is because the common dominant frequency is the dominant frequency due to the propagation path, geology, and the like. The above three methods have been exemplified as methods for generating vibration at the blasting point, but these methods are examples, and other methods may be adopted as long as the dominant frequency to be maintained can be obtained.

Next, the method of designing the optimum timetable will be described. In FIGS. 7 (b) and 8 (b), since there is only one protruding peak, the predominant frequency to be preserved can be regarded as one. However, it is not limited to the case where the predominant frequency to be maintained can be regarded as one. Therefore, the optimum timetable design considers the case where the dominant frequency to be maintained can be regarded as one and the case where a plurality of dominant frequencies must be considered. This design has different design methods depending on the case. First, a case where the dominant frequency to be maintained can be regarded as one will be described.

Since the vibration management target differs depending on the content of the maintenance target (difference in housing, factory, etc.), it is necessary to design according to the management target. Since vibration involves three factors: displacement, velocity, and acceleration, the management goals are: reduction of maximum speed, reduction of maximum vibration level related to acceleration, reduction of both maximum speed and maximum vibration level. There are four reductions in maximum displacement.

Here, the basis for setting the optimum second time interval is to set the detonation second time interval that is out of phase with respect to the dominant frequency in the maintenance target or the propagation path. Explaining with reference to FIG. 13, assuming that the vibration waveforms associated with a single detonation are the same, by superimposing the same waveforms at 1/2 wavelength intervals of the vibration waveforms such as the first stage waveform and the second stage waveform in FIG. The amplitude can be reduced as in the superimposed waveform in FIG.

In the example shown in FIG. 13, the interval of opposite phase is set to 1/2 wavelength, but it may be 3/2 wavelength, 5/2 wavelength, or the like. That is, the interval of the opposite phase can be n (n = 1, 3, 5, ...) / 2 wavelengths. This interval means that the vibration waveforms are superimposed at the second time interval, which is 2 / n times the dominant frequency.

Based on the above, the design method when each of the above four reductions is the objective as a management goal will be described in detail.

First, a case where the purpose is to reduce the maximum speed will be described. The optimum second time interval set for the detonator 21 is a second time interval that can sufficiently reduce vibration, and specifically, a frequency that is 2 / n times the dominant frequency in the maintenance target or the propagation path predominates. It is such a second time interval. This means that the amplitude of the superimposed waveform is reduced by superimposing the waveforms on the waveform shape of the dominant frequency at intervals of seconds that are in opposite phase.

Based on this, blasting is basically performed at a second time interval (2/3 times or 2/5 times the dominant frequency, etc.) that is on the lower frequency side than the dominant frequency in the maintenance target or the propagation path. This not only relies on the seconds interval of the opposite phase, but also reduces the overlap of the vibration waveforms that do not become the opposite phase due to the phase shift due to the difference in the propagation distance between the charging hole and the maintenance target, thereby increasing the maximum amplitude. It shall be suppressed, and the amount of simultaneous occurrence shall be reduced according to the control value.

Second, a case where the purpose is to reduce the maximum vibration level will be described. The vibration level is the acceleration level in which the acceleration of vibration is expressed in dB, and the sensory correction by the sensory correction filter is added. The smaller the frequency, the easier it is for a person to feel the vibration, and the larger the frequency, the smaller the amount of displacement, and the harder it is to feel. For this reason, the sensory correction filter is configured to correct frequencies that are easily perceived by humans to be large and frequencies that are difficult to perceive to be small.

FIG. 9 shows the vibration levels (dB) and elapsed time (ms) on the X-axis, Y-axis, and Z-axis when the above 7-stage waveform is vibrated on a timetable with a time interval of 20 ms and 100 stages. The graph showing the relationship between is shown. As shown in FIG. 11A, the maximum velocity is predominant in the horizontal X-axis and Y-axis, but the vibration level is predominant in the vertical Z-axis as shown in FIG. This is because it is affected by the sensory correction of the vibration level.

When the vibration level is the target, the above-mentioned sensory correction and the time constant, which is a measure of the time until equilibrium is reached, cause characteristics different from the magnitude relation of the waveform. For this reason, it is basic to set a short second interval and shift (drift) the dominant frequency to the high frequency side, based on the basic matter of setting the second time interval so that the frequency twice as above is dominant. Will be.

Based on this, based on excavation blasting at intervals of seconds such that the frequency twice the predominant frequency to be maintained is predominant, the effective value of vibration and the increase / decrease characteristics of the vibration level due to the sensory correction filter will be determined by detailed examination. Grasp and decide. That is, the purpose is to shift the predominant frequency of vibration to the high frequency side where it is difficult for humans to perceive vibration.

Third, a case where the purpose is to reduce both the maximum speed and the maximum vibration level will be described. Since the cases where each reduction is the purpose have already been described, if there is no conflicting part in each design method, set the second time interval that can reduce both the maximum speed and the maximum vibration level most. If there are conflicting parts, balance the two and set the second time interval. For example, it is possible to set a second time interval in which a frequency that is twice or two-thirds of the predominant frequency to be preserved is predominant.

Fourth, a case where the purpose is to reduce the maximum displacement will be described. The displacement due to vibration can be reduced by increasing the number of stages and keeping the amount of simultaneous generation small. That is, the number of holes may be increased and the amount of explosive per hole may be reduced. Further, the displacement can be reduced by drifting the dominant frequency of the vibration caused by the detonation to the high frequency side. That is, if the detonation is performed at short second time intervals, the dominant frequency can be drifted to the high frequency side.

It is important to understand that even if the time interval is short, if it is too short, the detonation efficiency may change significantly compared to normal blasting. For example, since the detonation efficiency is greatly improved, it becomes a state similar to that of a overload drug, and it takes time to slip out due to the spread of stepping stones from the face 11, and a sufficient free surface is not formed by the previous detonation. Since the next detonation will occur, the object will not crack and energy will blow out from the hole, causing a gun phenomenon. With this, crushing as planned cannot be performed.

In order to avoid the state of the overcharge and eliminate the occurrence of the gun phenomenon, etc., an interval of at least 5 ms or more should be provided. Therefore, the short second time interval may be, for example, 5 to 8 ms.

Next, a case where a plurality of dominant frequencies must be considered will be described. When it is necessary to consider a plurality of dominant frequencies, there are cases where there are a plurality of dominant frequencies to be maintained and the dominant frequencies are different for each axis. In this case, in the frequency characteristics of each axis, it is basic to set the predominant frequency due to the detonation to the non-dominant frequency.

In this case, a plurality of single-shot bursts are performed, and the maximum speed and the maximum vibration level are predicted by prediction by superimposition analysis of the obtained single-shot waveforms. From the prediction, set the detonation second time interval suitable for the site conditions.

For example, it is assumed that a plurality of single blasts are performed and a waveform similar to that shown in FIG. 6 is obtained. From these waveforms, the 7th stage waveform similar to FIG. 8 in which the dominant frequency can be confirmed is used as the representative waveform. In the superposition analysis of single-shot waveforms, the second-stage time interval is used as a parameter, and the time history characteristics when the seventh-stage waveform is vibrated at each second-stage time interval and a multi-stage timetable, and the frequency characteristics are Fourier transformed. Is obtained, the maximum speed is obtained from the time history characteristics, and the maximum vibration level is obtained from the frequency characteristics. The result is illustrated in FIG.

FIG. 10 is a diagram showing changes in the maximum speed and the maximum vibration level by making predictions using the second time interval as a parameter. This figure is a prediction diagram used to select the second time interval to be set in the timetable on the premise that the predominant frequency to be maintained obtained from the waveform of the 7th stage is correct. Incidentally, when the waveform of the fifth stage similar to that in FIG. 7 in which the dominant frequency can be confirmed is used, the characteristics of the analysis result are slightly changed. However, since it is a slight difference, any waveform can be used to create such a prediction diagram if the dominant frequency can be confirmed.

Referring to FIG. 10, when the second time interval is long, the change in the maximum velocity and the maximum vibration level is small. That is, it is stable. On the other hand, when the second time interval is short, the maximum speed and the maximum vibration level can be significantly reduced, but if the settings are incorrect, they may increase. In addition, the shorter the second time interval, the higher the possibility that an error will occur. In consideration of these facts, and based on the basic principle of setting the dominant frequency due to the detonation to the above-mentioned non-dominant frequency, the second time interval is set.

For example, if 33 Hz or 125 Hz is a non-dominant frequency, the second interval of 1000/125 = 8 ms or 1000/33 = 30 ms can be set so that the predominant frequency due to the detonation occurs at those frequencies. .. With reference to FIG. 10, setting 8 ms can significantly reduce the maximum vibration level compared to setting 30 ms. However, if the setting is incorrect, the maximum vibration level will be larger than when it is set to 30 ms, and there is a high possibility that an error will occur. Therefore, considering such risks, set the second time interval of 30 ms. Is desirable.

By the way, when the tunnel 12 is excavated by blasting, the positional relationship between the face 11 which is the blasting point and the maintenance target changes, and the vibration propagation path also changes. From this, it is highly possible that the propagation characteristics of the vibration propagating from the face 11 to the maintenance target also change. However, the propagation characteristics do not always change due to changes in the positional relationship between the face 11 and the object to be maintained due to tunnel excavation. It is a waste of work to review the timetable even though the propagation characteristics do not change.

Therefore, it is determined whether or not the timetable in step 345 of FIG. 3 needs to be reviewed. As a result, the amount of work can be reduced, and as a result, the construction period can be shortened.

The method of determining whether the timetable needs to be reviewed will be described in detail below. The timetable (seconds and time intervals) set for existing blasting patterns and the resulting predominant frequency are already designed and known. Therefore, the main blasting of step 325 in FIG. 3, the vibration measurement in step 330 is performed, the time history characteristics are obtained by extracting the propagation characteristics in step 335, and a diagram showing the frequency characteristics obtained from the time history characteristics is created. ..

Here, the 7th-stage waveform that can evaluate the propagation characteristics of the maintenance target shown in FIG. 8A is used as a representative waveform, and the time history characteristics when the waveform is oscillated on a 100-stage timetable at a second time interval of 20 ms are shown. , FIG. 11 (a), and the frequency characteristics thereof are shown in FIG. 11 (b). This shows the time history characteristics and frequency characteristics that are expected when blasting is performed in the current timetable.

FIG. 11A shows a diagram in which the waveform of the 7th stage is synthesized in 100 stages at intervals of 20 ms and a diagram in which the results of the 3 axes are combined for each axis. Specifically, 100 waveforms of the 7th stage are superposed with the phase shifted by 20 ms. In the time history characteristics shown in FIG. 11A, the maximum speeds in the horizontal direction of the X-axis and the Y-axis are large and outstanding. FIG. 11B shows the frequency characteristics obtained by Fourier transforming the time history characteristics of each axis.

The frequency characteristic shown in FIG. 11B has a sharp waveform, and a maximum value in which the spectrum rises and falls momentarily in increments of 50 Hz appears. When single blasting is performed for 20 ms each, blasting is performed 50 times per second, so the maximum value in increments of 50 Hz is the predominant frequency due to the timetable. Since the frequency characteristic shown in FIG. 8B is represented by a waveform having a peak only at 200 Hz, only 200 Hz is extracted as the dominant frequency to be maintained. This predominant frequency to be preserved overlaps with one of the maximum values appearing in the frequency characteristics shown in FIG. 11 (b). In this way, since the dominant frequency caused by the timetable can be grasped, it is possible to grasp whether the dominant frequency to be maintained has changed by constantly checking the change in the frequency characteristic of the measurement result.

If the frequency characteristic obtained by performing this rupture is the same as this predicted frequency characteristic, it indicates that the predominant frequency to be maintained does not change, and the currently set second time interval is the optimum second time interval. Therefore, it is considered that the vibration can be sufficiently suppressed as designed. Therefore, it can be determined that the review of the timetable is unnecessary. On the other hand, when the frequency characteristic changes, it indicates that the predominant frequency to be maintained has changed, and unlike the frequency characteristic shown in FIG. 11B, a new maximum value appears at another frequency. In this case, since the vibration may become large at the currently set second time interval, it is necessary to change the second time interval to suppress the vibration. Therefore, it can be determined whether or not the timetable needs to be reviewed depending on whether or not a new maximum value appears at another frequency.

However, since errors may occur in the vibration measurement and calculation process, even if a new maximum value appears, it is not judged that it needs to be reviewed immediately, and it depends on whether the predominant frequency to be maintained has changed by a certain amount or more. , It is desirable to determine whether the timetable needs to be reviewed. That is, it is desirable to determine whether or not the extracted predominant frequency to be preserved differs from the predominant frequency of the frequency characteristic shown in FIG. 11 (b) by a certain amount or more. Therefore, for example, it can be determined whether or not a review is necessary depending on whether or not the frequencies differ by 5% or more. The criterion for determination is not limited to 5% or more, but may be 7% or more or 10% or more. If it is too large, the number of reviews will decrease and vibration cannot be suppressed properly. Therefore, it is desirable to review when the difference is 5 to 10%.

Further, the criterion for determination is not uniformly set to 5% or more, but can be changed according to the predominant frequency to be preserved. For example, at a frequency with a small error of less than 100 ms, the determination reference value can be set to 5%, and at a frequency higher than that, the error becomes large, so the determination reference value can be set to 10%. This is just an example and is not limited to this value.

The frequency characteristic does not always have a waveform having only one peak as shown in FIG. 11 (b). The waveform may have two or more peaks. In addition, the frequency representing the peak may differ depending on each axis. Then, two or more predominant frequencies to be maintained can be obtained. In this case, it is possible to specify the predominant frequency to be preserved having the highest peak value, and determine whether or not a review is necessary based on whether or not the predominant frequency to be preserved has changed to a certain level or more.

In the above, it is determined whether or not the timetable needs to be reviewed based on whether or not the predominant frequency to be maintained has changed by a certain amount or more, but the present invention is not limited to this. For example, it may be determined based on whether or not the vibration energy has changed more than a certain level. Specifically, the area of the portion surrounded by the curve of the graph showing the frequency characteristic shown in FIG. 11B and the axis showing the frequency is calculated. Since the area is related to the above speed and the speed is proportional to the energy, when the area changes more than a certain amount, it is considered that the energy changes more than a certain amount. In this way, when the vibration energy changes more than a certain level, it can be determined that the timetable needs to be reviewed. The area calculation method can be any method known so far.

In particular, this energy is obtained when there are a plurality of preserved dominant frequencies and the area of the portion where other preserved dominant frequencies are present is larger than the area of the portion where the preserved dominant frequency having the above peak value exists. It can be judged based on the change of.

In this way, when it is determined that a review is necessary, the timetable is reviewed and this is continuously performed during tunnel excavation, so that the design suitable for the current predominant frequency to be maintained can always be maintained. ..

When the dominant frequency is high in the maintenance target, the above change is unlikely to appear in the frequency characteristics as shown in FIG. 11B, and the above method may not be effective. In this case, the procedure is complicated, but only the 6th to 10th steps of the centering part (including the auxiliary centering) are set so that a single waveform at 300ms intervals can be measured (the paying part on the outer peripheral side of the centering part). Will remain at the existing second time interval), and will be replaced (backed up) by predictive analysis using this measurement result.

If high-frequency vibration is predominant, it may change to the problem of solid sound transmitted through materials such as concrete, walls, windows, etc. of foundations of houses, etc., instead of air sound transmitted through air. There is sex. The size of solid sound differs between outdoors and indoors even if the vibration is the same, and it tends to be louder indoors than outdoors. Even with the same blasting, the magnitude of vibration differs between outdoors and indoors. Therefore, it is difficult to make an assumption in advance.

Therefore, if necessary, simultaneous measurement outdoors and indoors can be performed only once, and necessary measures can be taken based on the difference in the dominant frequency and the magnitude relationship of the amplitude obtained from the measurement results.

The Fourier transform of the waveform representing the above-mentioned time history characteristics, and whether or not the timetable needs to be reviewed depending on whether or not the predominant frequency to be preserved has changed by a certain amount or more is determined by the above-mentioned information processing device such as a PC. Can be carried out.

FIG. 12 shows an example of the hardware configuration of the information processing device. As hardware, the information processing device has a CPU (Central Processing Unit) 30, ROM (Read Only Memory) 31, RAM (Random Access Memory) 32, HDD (Hard Disk Drive) 33, and input / output, similar to a general-purpose PC. It includes an I / F 34, a display device 35, an input device 36, and a bus 37.

The CPU 30 executes a program stored in the ROM 31 or the HDD 33 and controls the operation of the entire information processing apparatus. The ROM 31 is a non-volatile memory that stores a BIOS (Basic Input Output System) executed when the information processing apparatus is started, various setting values, and the like. The RAM 32 is a volatile memory that provides a work area for holding a program read by the CPU 30 for execution. The HDD 33 is a non-volatile storage device that stores an OS, various programs, and various data. Here, the HDD 33 is used, but the present invention is not limited to this, and an SSD (Solid State Drive) or the like may be used.

In various programs, the time history characteristics are displayed based on the input vibration results, the frequency characteristics are obtained by Fourier transform, and the predominant frequency to be preserved is extracted from the frequency characteristics, the currently set seconds. It includes a program that determines the review of the timetable based on the expected changes in the predominant frequency for maintenance when the vibrations are vibrated multiple times at time intervals. The program can also execute a process of changing the second time interval currently set for each detonator 21 when the timetable is regarded. The change of the second time interval can be realized by changing the set value of the electronic timer included in each detonator 21.

The input / output I / F 34 is an interface for controlling the output of information to the display device 35 and the input of information from the input device 36. The display device 35 is a liquid crystal display, an organic EL display, or the like, and displays a waveform representing the time history characteristics and frequency characteristics, a determination result, and the like. The input device 36 is a mouse or a keyboard, and receives information input by the user. The bus 37 is connected to the CPU 30, ROM 31, and the like, and transmits an address signal, a data signal, and various control signals.

The information processing device also includes an external storage I / F, an SD card slot, a storage medium drive such as a CD-ROM or a DVD, an audio input device such as a microphone, an audio output device such as a speaker, and an image pickup device such as a camera. You may.

From the above, by providing the blasting method of the present invention, it is possible to easily determine whether or not it is necessary to review the optimum timetable (second time interval) in the blasting pattern using the electronically delayed electric detonator. Can be done. In addition, since it can be easily determined, it is possible to review the time interval per second in a timely manner, and the optimum design of the timetable according to the current predominant frequency to be maintained is always guaranteed. Therefore, the effect of suppressing vibration and noise using this electronic delay type electric detonator can be obtained as expected.

Although the rupture method of the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the above-described embodiments, and other embodiments, additions and modifications are made. , Deletion, etc. can be changed within the range that can be conceived by those skilled in the art, and any aspect is included in the scope of the present invention as long as the action / effect of the present invention is exhibited.

10 ... ground, 11 ... face, 12 ... tunnel, 13, 14 ... house, 15, 16 ... charge hole, 20 ... explosive, 21 ... detonator, 22 ... filling, 23 ... lead wire, 24 ... blaster, 25 ... checker, 26 ... connection counter, 30 ... CPU, 31 ... ROM, 32 ... RAM, 33 ... HDD, 34 ... input / output I / F, 35 ... display device, 36 ... input device, 37 ... bus

Claims (6)

It is a blasting method that uses an ignition device to blast.
A vibration process that blasts a part of the blasting target or hits a part of the blasting target,
A vibration measurement process that measures the vibration generated in the vibration process at a predetermined point away from the blasting target, and a vibration measurement process.
A characteristic extraction step of extracting the propagation characteristics of the vibration propagated to the predetermined point from the measurement results in the vibration measurement step by an information processing device, and a characteristic extraction step.
A step of setting the ignition timing of the ignition device based on the propagation characteristic extracted by the information processing apparatus in the characteristic extraction step, and a step of setting the ignition timing of the ignition device.
The process of blasting the blasting target at the set ignition timing ,
The process of measuring the vibration generated by blasting at the predetermined point,
A step of extracting the propagation characteristics of the vibration propagated to the predetermined point from the measurement results in the step of measuring by the information processing device, and a step of extracting the propagation characteristics.
Based on the propagation characteristics extracted in the extraction step by the information processing apparatus, a step of determining whether or not to change the set ignition timing, and a step of determining whether or not to change the set ignition timing.
It includes a step of changing the setting of the ignition timing so as to reduce the vibration at the predetermined point when it is determined to be changed by the information processing apparatus.
In the extraction step, the dominant frequency as the propagation characteristic is extracted from the vibration waveform represented by the measurement result in the measurement step.
In the determination step, whether or not to change the set ignition timing based on the predominant frequency extracted in the extraction step and the predominant frequency predicted when blasting occurs at the set ignition timing. Blasting method to judge . The first aspect of claim 1, wherein the measuring step, the extracting step, the determining step, and the changing step are repeated every time the face as the blasting target is blasted when excavating a tunnel in the blasting step. The described blasting method. In the determination step, it is determined whether or not to change the set ignition timing depending on whether or not the dominant frequency extracted in the extraction step differs from the predicted dominant frequency by a certain amount or more. , The blasting method according to claim 1 or 2 . In the determination step, the set ignition timing is determined depending on whether or not the vibration energy at the dominant frequency extracted in the extraction step differs from the vibration energy at the predicted dominant frequency by a certain amount or more. The rupture method according to claim 1 or 2 , which determines whether or not to change. In the characteristic extraction step, the waveform having the largest amplitude is used as a representative waveform from the measurement results having a plurality of waveforms, and the dominant frequency is extracted from the representative waveform.
The blasting method according to any one of claims 1 to 4 , wherein in the determination step, the predominant frequency in the case of blasting at the set ignition timing is predicted using the representative waveform. The vibration has three elements: displacement, velocity, and acceleration.
The blasting method according to any one of claims 1 to 5 , wherein in the step of changing, the setting of the ignition timing is changed so as to reduce at least one of the three elements.

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