JPH065299B2 - Artificial seismic wave generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an artificial seismic wave generator that explosively explodes explosives such as explosives to artificially generate a long-duration seismic wave.

<Prior Art> There are various experimental methods for the earthquake resistance test of various structures and the liquefaction test method of the ground, and as one of the experimental methods, there is a method of utilizing the explosive force of explosives.

In this method, explosives such as dynamite are buried in the ground, and the explosive force of the explosives is transmitted to the surrounding ground as seismic waves to perform seismic tests of structures and liquefaction of the ground. Is the way.

<Problems to be Solved by the Present Invention> The seismic wave generation technique described above has the following problems.

(A) In seismic resistance tests, it is desirable that the amplitude of the seismic wave at the seismic source is large and that the duration of the seismic wave is long.

However, in the conventional technology for detonating explosives to generate seismic waves, when ordinary blasting is used, the vibration generated in the ground near the explosion becomes a high frequency such as several tens Hz to several hundreds Hz. Therefore, it is unsuitable as a ground motion input wave.

Moreover, if the distance between the explosion source and the test body is increased, a large amount of explosive powder is required, which increases the cost of the experiment.

(B) In the liquefaction test of the ground, due to the high frequency of the seismic waves and the short duration of the seismic wave as described above, it was not possible to generate sufficient liquefaction in the ground, and the reliability of the experimental results It becomes less likely.

(C) As a method of generating seismic waves using the explosive force of blasting, research on controlling the explosion time of blasting is currently underway in the United States.

This method is to explode explosives in a steel pipe buried in the ground, and in particular, in order to prolong the duration of seismic waves, multiple explosives that explode explosives are bundled and stored in the steel pipe. , Is a method of generating seismic waves by detonating explosives in each charge pipe with a certain time difference.

However, in the method of generating seismic waves by bundling the charge pipes, the number of explosions is up to 3 stages due to the limitation of the diameter of the steel pipe that stores the bundle of charge pipes. The seismic wave cannot be obtained for a long duration as required by.

<Purpose of the present invention> The present invention has been made to solve the above problems, and can generate a seismic wave with a long duration, and can improve the reliability of the experimental results of various experiments. , An artificial seismic wave generator is provided.

<Structure of the Present Invention> An embodiment of the present invention will be described below with reference to the drawings.

<A> Overall Description of Artificial Seismic Wave Generator An example of an artificial seismic wave generator according to the present invention is shown in FIG.

This device is a charge tube 1 for loading and exploding explosives.
The storage container 2 for storing the charge pipe 1 and the like are the main components.

Hereinafter, a specific structure of the artificial seismic wave generator will be described.

<B> Charge tube The charge tube 1 is a cylinder whose upper and lower ends are closed for the purpose of accommodating a plurality of sets of explosives independently.

That is, the internal space of the charge tube 1 is partitioned by the partition wall 11 and a plurality of explosion chambers 12 to 14 are independently formed in the vertical direction.

In the present embodiment, a case will be described in which the charge tube 1 is configured by combining three short cylinders and a cylindrical partition wall 11 that is screwed onto the short cylinders to shield the short cylinders.

The side wall of the charge tube 1 is provided with an exhaust plug 15 or an opening for exhausting the explosion-produced gas generated in each of the explosion chambers 12 to 14 to the outside of the tube.

Explosive container 3 containing explosive 3 in each explosion chamber 12-14.
1 is accommodated, and each detonator container 31 is equipped with a delay detonator 32.

The flange 16 protruding from the upper end of the charge tube 1 is provided with a vent hole 17.

As will be described later, the amplitude of the seismic wave generated by the explosion of the explosive 3 is controlled by the loading amount of the explosive 3, and the frequency is controlled by the exhaust velocity of the explosion product gas exhausted from the exhaust plug 15.

<C> Storage Container The storage container 2 is a box that forms a hollow, substantially sealed body.

The upper opening of the storage container 2 is closed by a cap 6, and a discharge port 61 is opened on the plate surface of the cap 6.

A plurality of explosive pressure ports 21 are opened on the side wall of the storage container 2,
Further, the outer periphery thereof is covered with a cylindrical expansion / contraction rubber 4 so as to surround the explosion pressure ports 21.

The expansion / contraction rubber 4 is made of a known material such as rubber that has no air permeability and is flexible and stretchable.

The upper and lower ends of the expansion / contraction rubber 4 are adhered to the storage container 2 with an adhesive or the like, and the expansion / contraction rubber 4 is expanded by the discharge pressure of the explosion generated gas discharged from the explosion pressure port 21.

In the present embodiment, the case where the expansion / contraction rubber 4 is attached to both sides of the storage container 2 will be described, but it is of course possible to attach the expansion / contraction rubber 4 to only one side.

Inside the storage container 2, a charge pipe 1 is provided via a flange 16.
Is suspended and stored.

It is also possible to cover only a part of the side surface of the storage container 2 where the explosion pressure port 21 is opened with the expansion / contraction rubber 4.

<D> Gunpowder As the above-described gunpowder 3, for example, black gunpowder or smokeless gunpowder can be used.

Therefore, there is no fear of affecting the strengths of the charge tube 1 and the partition wall 11 at all.

Further, it goes without saying that explosives other than explosive 3 can be used.

Next, a method of operating the artificial seismic wave generator will be described.

(1) Preparation work The artificial seismic wave generator with the above structure is buried in the ground 5.

Further, as in the present embodiment, the backfilling earth and sand 51 may be filled in the gap between the artificial seismic wave generator and the underground 5.

(2) Start of Explosion Due to Time Difference First, the explosive 3 is detonated by the delay detonator 32 in the uppermost explosion chamber 12 in the charge tube 1.

(3) Generation of artificial seismic wave The explosion product gas generated in the uppermost explosion chamber 12 passes through the exhaust plug 15 at a constant speed and is discharged into the containment vessel 2 and then from the explosion pressure port 21 to the containment vessel 2. Is discharged to the outside.

Further, the gas produced by the explosion is generated by the expansion rubber 4 and the outer periphery of the containment
The expansion pressure is expanded by increasing the internal pressure in the sealed space formed between and.

The expansion force of the expansion / contraction rubber 4 acts on the ground 5 to generate the first seismic wave as shown in FIG.

Immediately after the explosion in the uppermost explosion chamber 12 is completed, the explosives 3 in the explosion chambers 13 and 14 located below the uppermost explosion chamber 12 are sequentially exploded from above with a time difference.

As a result, the second wave is generated by the explosion in the middle explosion chamber 13 immediately before the first wave generated by the explosion in the uppermost explosion chamber 12 ends, and the last wave immediately before the second wave ends. The third wave is generated by the explosion in the explosion chamber 14.

The upper half of the sine wave as shown in FIG. 3 can be generated by adjusting the opening sectional area ratio between the discharge port 61 and the exhaust plug 15.

It should be noted that when the explosions are generated in each of the explosion chambers 12 to 14 with a time lag, the gas generated by the previous explosion also enters the explosion chamber before the explosion, but the explosive container 31 for storing the explosive 3 is used. If you make it with heat insulating material such as Styrofoam,
It is possible to regulate martial bombing.

Further, when using explosives as an explosion source, it is expected that the gas produced by the explosion reacts with oxygen in the atmosphere to cause secondary thermal firing, making it difficult to adjust the pressure generated.

As a countermeasure in such a case, a non-combustible gas such as nitrogen gas is sealed in the storage container 2 to deal with it.

Further, if the upper thickness of the expansion / contraction rubber 4 is formed thinner than the lower thickness, a large pressure acts on the ground in contact with the upper side of the expansion / contraction rubber 4, so that shearing force can be applied to the ground.

<Other Embodiment 1> In the above embodiment, the case where one charge pipe 1 is stored in the storage container 2 has been described. However, as shown in FIG. It is also possible to store a plurality of 1's.

That is, this embodiment is an example in which three charge tubes 1 having three explosion chambers 12 to 14 are stored, and artificial seismic waves of a total of 9 stages can be obtained.

Other structures are the same as those in the above embodiment,
The same reference numerals are given and the description thereof is omitted.
Is an exhaust port opened on the side surface of the charge tube 1.

Further, the operating method of the artificial seismic wave generator of this embodiment is basically the same as that of the above-mentioned embodiment in that the explosion chambers 12 to 14 in the respective charge tubes 1 are sequentially exploded with a time difference. The difference is that the number of explosions, that is, the number of generated seismic waves increases as the number of explosion chambers 12 to 14 increases, and the duration of seismic waves increases.

In the case of the present embodiment, the size of the storage container 2 is determined according to the number of the charge tubes 1 to be stored.

Further, the number of explosion chambers 12 to 14 formed in one charge tube 1, the number of stored charge tubes 1 and the size of the artificial seismic wave generator are appropriately determined depending on the geology and the purpose of the experiment.

<Other Embodiment 2> (Figs. 5 and 6) In the above-mentioned embodiment, the case where the artificial seismic wave is generated by utilizing the explosive force of the explosive has been described. Can be generated.

The details will be described below with reference to the drawings.

In this embodiment, the side wall of the hollow container 7 having a large number of vent holes 71 on its side surface is covered with the expanding / contracting rubber 4, and the hollow container 7 is buried in the ground 5 so that compressed air is compressed in the hollow container 7. Is a technique for generating a seismic wave in which the expansion / contraction rubber 4 is expanded by intermittently supplying the seismic wave.

<A> Structure of Hollow Container The hollow container 7 is a hollow box, and a large number of vent holes 71 are formed on its side surface.

Further, the circumference of the side surface of the container 7 is covered with the entire ventilation port 71 to which the expansion / contraction rubber 4 made of an elastic member is attached and exposed.

<B> Compressed air supply means On the ground side, a pressure vessel 8 such as a compressor or manlock
Is arranged, and the pressure vessel 8 and the hollow vessel 7 are connected by an air supply pipe 72.

Further, an air supply pipe 73 for opening and closing the flow path is arranged on the way of the air supply pipe 72.

The hollow container 7 is opened and closed by opening and closing the air supply valve 73.
It is configured so that compressed air can be intermittently supplied therein.

<C> Exhaust means In order to repeatedly supply compressed air into the hollow container 7, unless the previously supplied compressed air is removed, the internal pressure of the hollow container 7 becomes high and air cannot be supplied. After that, it is necessary to evacuate and reduce the internal pressure in the hollow container 7.

For that purpose, for example, an exhaust pipe 74 is attached to a part of the side surface of the hollow container 7, and an exhaust valve 75 is attached on the way of the exhaust pipe 74.

As the air supply valve 73 and the exhaust valve 75, for example, a well-known electromagnetic valve or an on-off valve operated by air pressure using a compressor can be used.

<D> Method of generating seismic wave (1) Air supply First, with the exhaust valve 75 closed, only the air supply valve 73 is opened to send compressed air into the hollow container 7.

The compressed air pumped into the hollow container 7 expands the expansion / contraction rubber 4 through the ventilation port 71.

When the expansion / contraction rubber 4 expands, the expansion pressure of the expansion / contraction rubber 4 presses the surrounding ground to generate a first wave.

(2) Exhaust When the air supply valve 73 is closed after a certain period of time, the exhaust valve 75 is released to exhaust the air.

As a result, the expansion / contraction rubber 4 restores while reducing the pressure applied to the surrounding ground.

(3) Re-airing Immediately before the first wave ends, the exhaust valve 75 is closed and the air-supplying valve 73 is opened again to expand the expansion / contraction rubber 4 to generate the second wave.

Hereinafter, the supply of the air and the exhaust are repeated to periodically generate a seismic wave.

In addition, when the free ends of the air supply pipe 72 and the exhaust pipe 74 connected to the hollow container 7 are connected to a piston type compressor or the like capable of alternately transmitting compressed air and generating negative pressure, the piston reciprocates. It is also conceivable that air supply and exhaust are performed by a single device.

<E> Effect of this Embodiment According to this embodiment, the following effects can be obtained.

(A) Since compressed air is used, seismic waves with long duration can be repeatedly generated.

Therefore, when used in the case of a ground liquefaction test, the occurrence of liquefaction can be grasped extremely accurately, and the liquefaction resistance force and the effect of liquefaction countermeasure work can be reliably evaluated. .

(B) By selecting the pressure of compressed air, the air supply time, and the exhaust time, it is possible to obtain a desired pressure force on the ground and a cycle of seismic waves.

(C) By selecting the thickness of the air supply pipe or the exhaust pipe, the rate of pressure increase in the hollow container can be controlled.

<Other Embodiment 3> (FIGS. 7 and 8) In the above-described embodiment, the case where the expansion / contraction rubber 4 is expanded / contracted by using air pressure to generate a seismic wave has been described, but the container itself without the expansion / contraction rubber 4 is used. It is also possible to inflate and generate seismic waves.

Examples will be described below.

<B> Structure of expansion / contraction container The expansion / contraction container 9 has a pin 93 at the lower ends of the two side surfaces 91, 92.
It is a wedge-shaped hollow box body that is rotatably supported by.

Specifically, the upper end of one side surface 91 is integrally connected to the ceiling 94, and the plate surface of the ceiling 94 is connected to the air supply pipe 95 and the exhaust pipe 96 in the same manner as in the above-described embodiment.
An air supply valve 97 and an exhaust valve 98 are attached to 5 and 96.

In addition, the upper end of the other side surface 92 is bent inward to make a ceiling 94.
It is inserted in and out of the inner surface of the.

Furthermore, between the upper surface of the bent side surface 92 and the ceiling 94,
A sealing material S is interposed to maintain the airtightness inside the expansion / contraction container 9.

In addition, a dedicated port 99 for supplying and exhausting air is provided on the curved surface of the side surface 92 on which the ceiling 94 is laminated.

<B> Seismic wave generation method (1) Air supply When the air supply valve 97 is opened with the exhaust valve 98 closed, compressed air flows into the expansion / contraction container 9 from the pressure container 8 connected to the air supply pipe 95. The inner wall of the expansion / contraction container 9 is pressurized.

Although the pressing force acts on the inner surface of the expansion / contraction container 9 on average,
Since the lower ends of both side surfaces 91 and 92 are rotatably supported, they are extruded outward to press the surrounding ground.

As a result, the first wave is generated.

(2) Exhaust After a lapse of a fixed time, the air supply valve 97 that has been released is closed and the exhaust valve 98 is opened to exhaust the compressed air in the expansion / contraction container 9.

(3) Resupply Air Just before the end of the first wave, the exhaust valve 98 is closed and the supply valve 97 is opened again to expand the expansion / contraction container 9,
Generate a second wave.

Hereinafter, the opening and closing operations of the air supply valve 97 and the exhaust valve 98 are repeated to periodically generate seismic waves, as in the above-described embodiment.

The effect of this embodiment is similar to that of the above-mentioned embodiment.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be obtained.

(A) Since the explosive force can be transmitted to the ground through the time difference in the ground, it is possible to generate an artificial seismic wave (earth motion) with a long duration close to the actual seismic wave.

Therefore, when this device is used for the liquefaction experiment of the ground, the liquefaction resistance can be evaluated more reliably and the effect of the liquefaction countermeasure work can be evaluated reliably.

In addition, when this device is used for seismic resistance experiments, artificial seismic waves with a lower frequency are generated compared with the case of exploding explosives in the ground. , It is possible to accurately calculate the damping constant of the ground.

(B) By controlling the explosive energy of the explosive, it is possible to easily generate a seismic wave having an arbitrary pressure and frequency.

(C) A large amount of energy can be easily generated by using gunpowder.

(D) A seismic wave having a long duration can be obtained by increasing the number of explosion chambers formed per charge tube or increasing the number of charge tubes stored in the storage container.

Therefore, the size of the containment vessel is not limited as in the conventional technique of generating a seismic wave by using a steel pipe as the containment vessel.

(E) In the present invention, the explosive port is surrounded by a rubber tube, and the explosive force is transmitted to the ground by expanding the rubber tube by the explosive pressure.

Therefore, the explosive force is increased by the large area rubber tube.
It can be efficiently transmitted to the ground.

[Brief description of drawings]

1 is a perspective view of an artificial seismic wave generator according to the present invention. FIG. 2 is a longitudinal sectional view thereof. FIG. 3 is an explanatory view of the generation state of artificial seismic waves. Explanatory diagram of an embodiment Fig. 5 and 6: Explanatory diagram of an example of generating a seismic wave using compressed air. Fig. 7 and 8: Explanatory diagram of another example of generating a seismic wave using compressed air.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashige Muramatsu 47-1, Shirane-cho, Asahi-ku, Yokohama-shi, Kanagawa Taisei Building Dormitory (56) References JP-A-60-161582 (JP, A) JP-B Sho-50 -24682 (JP, B1)

Claims (1)

[Claims] 1. An opening group is provided on a side wall of the storage container, and a side surface of the storage container is surrounded by a flexible expansion / contraction rubber that surrounds the opening group. Artificial seismic wave generator that contains one or more charge tubes with an explosion chamber