JP2000214268A - Elastic wave measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small elastic wave measuring device capable of utilizing a boring hole with rough and narrow hole wall surface and exactly measuring elastic wave transmitting in a set section. SOLUTION: The elastic wave measuring device 10 for burying in a hole (boring hole H) and measuring elastic wave is provided with an oscillator and a receiver consisting of pressure sensors (piezoelectric elements 11 and 12) having an oscillation function and a reception function of elastic wave with a specific interval. It also has a hole wall surface fixing means (water packer 14) for fixing the oscillator and the receiver on the wall surface H1 in the hole by directly or indirectly pressing the oscillator or the receiver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic wave measuring device for measuring an elastic wave by being inserted into a hole formed in the ground or the like.

[0002]

2. Description of the Related Art When constructing a structure such as a tunnel,
It is common practice to measure the velocity of an elastic wave in order to grasp the properties of the target ground using the velocity of the elastic wave propagating in the ground.

As shown in FIG. 4, conventionally, a boring hole H (for example, a hole drilled from a tunnel wall of a tunnel T) is used.
In general, an elastic wave oscillated from an oscillator 111 installed outside is received by a vibration receiver 112 installed in a borehole H, and its arrival time is measured to measure the elastic wave. However, in this method, the distance from the oscillation point to the vibration receiving point becomes longer as compared with the case where oscillation and vibration are received by one device installed in the borehole H,
Since the propagation path of the elastic wave (for example, a to c shown in FIG. 4) becomes complicated, there is a problem that the measurement accuracy is reduced.

[0004]

On the other hand, when an elastic wave is measured by one device installed in the hole, a boring hole for measurement is excavated, and an elastic wave measuring device ( Hereinafter, the measurement is performed by installing a “measuring device”. At this time, a new boring hole for measurement was drilled using a rotary rock drill or the like at each measurement so that the hole wall surface became smooth. In addition, there are many problems, such as the increase in cost due to the time and effort required, and the delay in the progress of construction work. Therefore, if it is possible to perform elastic wave measurement using boring holes that are drilled when reinforcing structures in the ground with rock bolts, etc., it is possible to minimize the effect on construction and reduce costs. The evaluation of the ground condition by the elastic wave velocity can be performed.

However, the above-mentioned boring holes for rock bolts have a very small hole diameter of 66 mm at the maximum and are excavated at a high speed by a rotary impact hydraulic excavator, so that the wall surface of the hole is not smooth. there were. In addition, in the prior art, it is difficult to miniaturize the measuring device because the oscillator and the geophone are mechanical, and a small measuring device in which the elastic wave oscillator and the geophone are housed in the same housing is manufactured, and the boring hole It was difficult to install the measuring device in the above.

Further, the measuring device has a structure having a length in the longitudinal direction because the oscillator and the geophone must be provided apart from each other by a certain length of the measuring section. Therefore, even if the measuring device is reduced in size to a size that can be installed in the boring hole for the lock bolt, in order to install the measuring device on a non-smooth hole wall surface having irregularities, the measuring device having a certain length must be stable. Therefore, a fixing mechanism for fixing the target is required.

[0007] Furthermore, when the measuring device is miniaturized and accurate measurement is performed, it is necessary to eliminate the influence of the elastic wave propagating not inside the ground but inside the measuring device among the elastic waves propagating from the oscillator to the geophone. . However, it was difficult to take appropriate measures due to the spatial restriction that a measuring device had to be installed in a narrow borehole.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to use a single boring hole having a rough hole wall surface and a narrow boring hole, and an elasticity propagating in a set section. It is an object of the present invention to provide a small elastic wave measuring device capable of accurately measuring a wave.

[0009]

In short, an elastic wave measuring apparatus according to claim 1 is an elastic wave measuring apparatus for measuring an elastic wave by being inserted into a hole, and has an elastic wave oscillating function and an elastic wave oscillating function. An oscillator including a pressure sensor having a vibration receiving function and a vibration receiver are provided at predetermined intervals, and the oscillator and the vibration receiver are directly or indirectly pressed on the hole wall surface in the hole by pressing the oscillator and the vibration receiver. It has a hole wall fixing means for fixing the

Here, a piezoelectric element is used as the pressure sensor,
A strain sensor or the like can be used. In particular, a piezoelectric element has good responsiveness despite its small size and can be operated with a small amount of energy. Therefore, the piezoelectric element is very suitable for miniaturizing a measuring device.
It is very preferable to use various packers such as an air packer and a liquid packer as the hole wall fixing means in order to simplify the measuring device.

Therefore, according to the present invention, by using an appropriate oscillator and a geophone, such as a piezoelectric element,
The size of the device can be reduced. Further, by using the hole wall surface fixing means, it becomes possible to stably fix the measuring device even in a boring hole having a rough hole wall surface, so that it is possible to more accurately measure an elastic wave.

Further, the elastic wave measuring device according to claim 2 is
2. The elastic wave measuring apparatus according to claim 1, wherein the oscillator and the geophone can change their roles mutually.

Therefore, according to the present invention, the roles of the oscillator and the geophone can be mutually changed by switching the input and output signal paths by using an electric circuit or the like. In the same measurement section, two types of measurements can be performed using the same measuring device while changing the oscillation position and the vibration receiving position. Therefore, it is possible to more accurately measure the elastic wave.

The elastic wave measuring device according to claim 3 is
3. The elastic wave measuring apparatus according to claim 1, wherein the oscillator or the vibration receiver is attached to a measurement device main body via a vibration absorbing member, so that the vibration receiver is connected to the oscillator via the measurement device main body. The characteristic feature is that the elastic wave transmitted directly to is attenuated and eliminated. Here, it is particularly preferable to use a vibration-proof rubber as the vibration absorbing member.

Therefore, according to the present invention, by attaching an oscillator or a geophone to the measuring device main body via the vibration absorbing member, the vibration absorbing member absorbs the elastic wave emitted from the oscillator, and the elastic wave is generated. It is possible to prevent the light from propagating in the measurement device main body and reaching the geophone. This makes it possible to measure the elastic wave very accurately.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.

First Embodiment As shown in FIG. 1, a main part of an elastic wave measuring apparatus 10 (hereinafter, referred to as "measuring apparatus") of the present invention comprises a piezoelectric element 11,
12, a connecting plate 13, a water packer 14 as a hole wall fixing means, and a vibration-proof rubber 15 and a vibration-proof rubber spacer 16 as vibration absorbing members. Piezoelectric elements 11 and 12 having a function of oscillating an elastic wave and a function of receiving a vibration are used for the oscillator and the geophone. The two piezoelectric elements 11 and 12 are connected to a control device S (FIG. 2) via a preamplifier 20 having an oscillation / vibration switching circuit therein, and the input and output signal paths are switched by an electric circuit. It is possible to change the role of the oscillator and the geophone.

The piezoelectric elements 11 and 12 are fixed to both ends of the connecting plate 13 via anti-vibration rubber 15 and a sensor pedestal 17 in a state where the piezoelectric elements 11 and 12 are separated from each other by a section length of an elastic wave measuring section. Both ends of the connection plate 13 and the sensor pedestal 17 are sandwiched between bolts 18 and nuts 19. In addition,
Bolt holes are formed at predetermined positions of the connection plate 13, the vibration isolating rubber 15, and the sensor pedestal 17.
Numeral 8 is screwed into the bolt hole via an anti-vibration rubber spacer 16. Thereby, the elastic wave oscillated by the oscillator can be absorbed by the vibration isolating rubber 15 and the vibration isolating rubber spacer 16 and can be attenuated and eliminated, so that the elastic wave propagates through the connecting plate 13 and reaches the geophone. Can be prevented.

On the back side of the connecting plate 13 on the fixing surface of the piezoelectric elements 11 and 12, a water packer 14 serving to press the two piezoelectric elements 11 and 12 against the hole wall surface H1 via the connecting plate 13 is provided. It is attached by a packer fixing member 25. The packer fixing member 25 has an upper side surface attached to the protective tube 22 and a lower surface connected to the connecting plate 13.
It is fixed on top. The water packer 14 is provided with the water pipe 2
4 and is formed of a rubber tube 14a capable of storing water therein. Further, since the side surface of the tube 14a is not covered with the protective tube 22, it can be expanded toward the external space by being supplied with water.
Therefore, when the water is supplied, the water packer 14 expands the tube 14a so as to protrude outside the protective tube 22, and comes into contact with the hole wall surface H1 to obtain a reaction force from the hole wall surface H1 and the connecting plate. The reaction force is also transmitted to the connecting plate 13 by expanding to the side of the connecting plate 13. for that reason,
The piezoelectric elements 11 and 12 are pressed in the direction of the hole wall surface H1 via the connecting plate 13, the vibration isolating rubber 15, and the sensor pedestal 17, and are fixed to the hole wall surface H1.

The preamplifier 20 serves to switch between oscillation and reception of the piezoelectric elements 11 and 12 and to amplify an electric signal of the received elastic wave.
Are connected to the piezoelectric elements 11 and 12 by the conducting wire 23. The piezoelectric elements 11 and 12, the connection plate 13 and the preamplifier 20 are housed inside a protection tube 22. However, a hole is formed in a portion of the protective tube 22 corresponding to the mounting position of the piezoelectric elements 11, 12, and a part of the lower surface of the piezoelectric elements 11, 12 protrudes from the hole,
It has a structure capable of contacting the hole wall surface H1.

Further, a rod R for taking the measuring device 10 into and out of the boring hole H is provided in the protective tube 22 and supplies power to the piezoelectric elements 11 and 12 and the preamplifier 20 for oscillation and vibration. Conducting wire 2 for passing electric signals to and from piezoelectric elements 11 and 12 outside
3, and a pipe 21 having a water supply / drainage pipe 24 for water supply / drainage to the water packer 14 is attached to the rod R. In addition, as shown in FIG. 2, the conducting wire 23 and the water supply / drainage pipe 24 are connected to the control device S and the water supply pump P, respectively. Here, the control device S is a device for controlling the entire operation of the measuring device 10, and includes, for example, a switch for oscillating / receiving vibration of the piezoelectric elements 11 and 12, a control unit for sending / draining the water packer 14, and the like. ing. The control device S is connected to a power supply unit (not shown), a data input / output device, a data analysis unit, and the like.

The measuring device 10 according to the first embodiment of the present invention is configured as described above. The measuring device 10 uses the boring hole H drilled from the tunnel wall of the tunnel T to elastically measure the elasticity. A method for measuring a wave will be described.

First, as shown in FIG. 2, the rod R is operated to insert the measuring device 10 at a position for measuring an elastic wave in the excavated borehole H. Next, the control device S injects water into the water packer 14 via the water pipe 24. Then, as shown in FIG. 1B, the tube 14a of the water packer 14 expands and comes into contact with the hole wall surface H1. Thereafter, when the water supply is continuously performed, the reaction force received by the tube 14a from the hole wall surface H1 via the connecting plate 13 causes
Since a downward force is applied to the piezoelectric elements 11 and 12, the piezoelectric elements 11 and 12 come into contact with the hole wall surface H1 and the measuring device 1
0 is fixed to the hole wall surface H1.

Subsequently, the control device S controls the preamplifier 20.
Is set so that the piezoelectric element 11 is an oscillator and the piezoelectric element 12 is a vibration receiver. Then, the elastic wave oscillated from the oscillator (piezoelectric element 11) is transmitted to the vibration receiver (piezoelectric element 1).
2), its arrival time, waveform, etc.
The first measurement is performed by measuring the path A) shown in FIG. Thereafter, the control device S operates the preamplifier 20 to change the piezoelectric element 12 to an oscillator and the piezoelectric element 11 to a vibration receiver, and to transmit the elastic wave oscillated from the oscillator (piezoelectric element 12) to the vibration receiver (piezoelectric element 11). ), The same measurement (path B shown in FIG. 2) as in the first measurement is performed.

After the measurement is completed, the controller S is operated to
By draining the water from the tube 14a of the water packer 14, the restraint from the hole wall surface H1 of the measuring device 10 is released, the measuring device 10 is moved to the next measuring position, and the above operation is repeated.

As described above, since the oscillator and the geophone can be switched to each other, the input and output signal paths are switched by an electric circuit, so that the oscillation position and the oscillation position can be changed at the same measurement position. Since two types of measurement can be performed, it is possible to measure the elastic wave very accurately.

In the above-described measurement of the elastic wave, the elastic wave oscillated from the oscillator passes through the ground and is measured by the geophone. At that time, it is conceivable that the elastic wave generated by the oscillator propagates through the connecting plate 13, that is, the inside of the main body of the measuring apparatus 10, and reaches the geophone. However, since the oscillated elastic wave can be absorbed by the vibration-isolating rubber 15 and the vibration-isolating rubber spacer 16, the problem does not occur. Therefore, only the elastic wave that has passed through the target ground can be measured. it can.

Second Embodiment The measuring device 30 of the second embodiment differs from the measuring device 10 of the first embodiment only in the hole wall fixing means. Therefore, the description will be made only for the portion related to the hole wall surface fixing means, and the members and the like which have the same role as the members and the like already described will be denoted by the same reference numerals and the description thereof will be omitted.

The hole wall surface fixing means according to the second embodiment of the present invention also has a structure in which the water packer 34 is used, but the water packer 34 is provided inside the protection tube 42. This is different from the case of the first embodiment. As shown in FIG. 3, packer position holding guides 41 are provided at both ends of the water packer 34, and the water packer 34 is fixed to the upper inner wall surface of the protection tube 42 by the packer position holding guides 41. Have been. Also,
A leaf spring 45 is provided between the connection plate 13 and the protection tube 42 on the side of the piezoelectric elements 11 and 12 to urge the connection plate 13 and the protection tube 42 in a direction separating from each other. Further, guide stoppers 46 are provided on the lower inner wall surface of the protection tube 42 on both side surfaces of the piezoelectric elements 11 and 12.

The piezoelectric elements 11 and 1 of the protective tube 42 are
A hole is formed at a position corresponding to the mounting position of 2, and the piezoelectric elements 11 and 12 can freely protrude and retract from the hole. Further, the connecting plate 13 is not fixed to the protection tube 42, and is formed so as to be movable inside the protection tube 42 to a position where the sensor pedestal 17 contacts the guide stopper 46.

The measuring device 30 according to the second embodiment of the present invention is configured as described above.
Is fixed to the hole wall surface H1 in the boring hole H. The other method of measuring the elastic wave is the same as that of the first embodiment, and the description is omitted.

First, by operating the control device, the water supply / drainage pipe 24 is operated.
, Water is injected into the water packer 34. Then, as shown in FIG. 3B, the tube 34 of the water packer 34
a expands inside the protection tube 42. The expanded tube 34 a receives a reaction force from the tube wall of the protection tube 42 and presses the connecting plate 13. Here, since the piezoelectric elements 11 and 12 are attached to the connecting plate 13, when the connecting plate 13 is pressed by a downward force, the piezoelectric elements 11 and 12 protrude to the outside of the protective tube 42, and the hole wall surface is formed. Contact H1. Therefore, when water is continuously injected into the water packer 34, the measuring device 30 will eventually contact the lower contact surfaces of the piezoelectric elements 11 and 12 and the hole wall surface H1 at the upper surface of the protective tube 42. Therefore, it is fixed stably.

Further, after the measurement is completed, the controller S is operated to drain the water from the tube 34a of the water packer 34 through the water supply / drain pipe 24. Then, protection tube 4
The reaction force from the tube wall of No. 2 is eliminated, and the leaf spring 45
2 is urged in the direction in which the connecting plate 34 and the protective tube 42 are separated from each other, so that the piezoelectric elements 11 and 12 are drawn into the protective tube 42, and the restriction from the hole wall surface H1 is released. .

Since the measuring device 30 of the second embodiment is entirely covered with the protective tube 42, damage and the like may occur when the device is inserted and withdrawn when compared with the first embodiment. There is an advantage that there is little.

As described above, an example of a preferred embodiment of the present invention has been described. However, the present invention relates to the measuring device 1 described above.
The design of each of the above components is not limited to 0 and 30, and design changes can be made as appropriate without departing from the spirit of the present invention.

In particular, the hole wall surface fixing means is a means for directly or indirectly pressing the oscillator and the vibration receiver to fix the oscillator and the vibration receiver to the hole wall surface, and is limited to the water packer. Never. Therefore, it is needless to say that the oscillator and the geophone may be fixed to the hole wall surface by obtaining a reaction force from the hole wall surface or the protection tube by a plurality of hydraulic jacks or the like.

[0037]

As described above, since the elastic wave measuring apparatus of the present invention can be reduced in size, it is very lightweight, and the elastic wave measuring operation can be performed only by human power. You can do that in time. Further, the elastic wave measurement operation can be performed using a boring hole whose hole wall surface is not smooth, and a new boring for measurement is not required, so that the cost required for measurement can be reduced. Further, since the elastic wave can be measured in an arbitrary section in the hole, it is possible to easily and accurately grasp the properties of the target ground.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a first embodiment of an elastic wave measuring apparatus according to the present invention, wherein FIG. 1 (a) shows insertion and withdrawal of an elastic wave measuring apparatus into a boring hole, and FIG. This shows a state where the elastic wave measuring device is fixed.

FIG. 2 is a conceptual diagram in a case where an elastic wave is measured using the elastic wave measuring device of the present invention.

FIG. 3 is a side sectional view of a second embodiment of the elastic wave measuring device according to the present invention, in which (a) shows insertion and extraction of the elastic wave measuring device into a boring hole, and (b) shows This shows a state where the elastic wave measuring device is fixed.

FIG. 4 is a conceptual diagram in a case where a conventional elastic wave is measured.

[Explanation of symbols]

 T Tunnel H Boring hole H1 Hole wall surface R Rod S Controller 10,30 Elastic wave measuring device 11,12 Piezoelectric element 13 Connecting plate 14,34 Water packer 14a, 34a Tube 15 Anti-vibration rubber 16 Anti-vibration rubber spacer 20 Preamplifier 22, 42 Protection tube 41 Packer position holding guide 45 Leaf spring 46 Guide stopper

Continuation of front page (72) Inventor Tomoyuki Aoki 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo F-term (reference) in Taisei Corporation 2D043 AB08 BA10

Claims (3)

[Claims] 1. An elastic wave measuring device for measuring an elastic wave by being inserted into a hole, wherein an oscillator and a geophone comprising a pressure sensor having an elastic wave oscillating function and a vibration receiving function are separated by a predetermined distance. Elastic means, which has hole wall fixing means for directly or indirectly pressing the oscillator and the geophone on the wall of the hole to fix the oscillator and the geophone on the hole. Wave measuring device. 2. The apparatus according to claim 1, wherein said oscillator and said geophone can change their roles mutually.
An elastic wave measuring apparatus as described in the above. 3. By attaching the oscillator or the geophone to a measuring device main body via a vibration absorbing member,
3. The elastic wave measuring apparatus according to claim 1, wherein the elastic wave transmitted directly from the oscillator to the vibration receiver via the measuring apparatus main body is attenuated and eliminated.