JP3366624B2 - Elastic wave velocity measuring apparatus and method for installing and removing elastic wave velocity measuring apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic wave velocity measuring device which is easy and reliable to install and collect in a hole of a sensor used when investigating the quality of rock around a building by elastic wave velocity measurement. The present invention relates to a method for installing and removing an elastic wave velocity measuring device.

[0002]

2. Description of the Related Art Conventionally, in underground civil engineering works such as tunnels, rock mass surveys have been generally performed to judge the quality of rock mass around a building. An elastic wave velocity measuring method is available as a rock mass survey method. This elastic wave velocity measurement method is a method of analyzing the refraction phenomenon of elastic waves due to differences in the density and rigidity of the formation, and a sensor is installed on the ground surface or in the ground to measure the artificially transmitted elastic waves. The arrival time is measured. As a sensor installed on the ground surface or in the ground to measure the velocity of an elastic wave, when measuring on the ground surface, for example, a speedometer such as Geophone (trade name) is used. In this case, an accelerometer that can be made smaller is often used.

In order to measure the elastic wave velocity with high accuracy, it is important that the sensor is securely fixed to the ground surface or a groove provided in the ground. In the case of, for example, after making a hole in the rock with an electric drill and inserting the pin attached to the sensor into the hole, fix the sensor with gypsum, or drive the hole-in anchor into the hole. After that, a method of attaching a screw to the sensor and fixing the sensor by screwing it into the hole-in anchor has been performed. In contrast,
In the case of measurement in the ground, in order to collect data in multiple directions (for example, three directions) in a small underground space, in addition to wanting to use a fixing method that is as easy as possible, in addition to collecting the sensor as much as possible, etc. Due to the restriction of, it is more difficult than the measurement on the ground surface.

As a conventional elastic wave velocity measuring device for measuring the elastic wave velocity in the ground, for example, the device disclosed in Japanese Patent No. 3053089 (see FIG. 6) is known. There is. The elastic wave velocity measuring device 100 shown in FIG. 6 is a strip-shaped leaf spring 1 made of a superelastic alloy.
01, a hollow pipe 102 to which both ends 101a of the leaf spring 101 are attached, a joint 103 for connecting the hollow pipes 102, and a leaf spring fitting 10 for attaching the both ends 101a of the leaf spring 101 to the hollow pipe 102.
4 (fixed plate spring mounting member 104a, movable plate spring mounting member 104b), and a sensor unit 106 that is roughly configured by a piezoelectric element 105 mounted on the inner surface of the plate spring 101 and serving as a sensor. , A gap filling member (not shown), which is a hollow bag-like body that fills a gap between the hollow pipe 102 of the sensor unit 106 and the leaf spring 101, and movement for moving the movable leaf spring attachment. Control means 107 (pin 107a, wire 10
7b). The piezoelectric element 105 and a personal computer (not shown) are connected to each other via a lead wire that passes through the hollow pipe 102.

According to the elastic wave velocity measuring device 100, when the leaf spring 101 is crushed in advance and is plastically deformed and is put into the groove hole 108, the leaf spring 101 presses the wall surface 108a of the groove hole 108. In this way, the piezoelectric element 105 attached to the inner surface side of the leaf spring 101 comes into close contact with the wall surface 108a via the leaf spring 101, so that the measurement accuracy can be improved. Then, when collecting the sensor unit 106,
By operating the cable 107b, the pin 107a that fixes the movable plate spring mounting tool 104b is removed, and the movable plate spring mounting tool 107a is separated from the fixed plate spring mounting tool 104a along the longitudinal direction of the hollow pipe 102. The height of the leaf spring 101 is lowered by moving the plate spring 101 to, and the sensor unit 106 can be easily collected.

The gap filling member is attached between the leaf spring 101 and the hollow pipe 102, and the leaf spring 101 and the hollow pipe 10 are filled with water, air or the like for expansion.
It is possible to prevent rock fragments or the like from being caught in the gap between the two and the effect that the collection of the sensor unit 106 becomes easier.

[0007]

However, in the above-described conventional elastic wave velocity measuring device 100, as shown in FIG. 7, when the slot 108 provided in the ground is not self-supporting, for example, after excavating the slot, When the diameter of the rock hole 108b around the groove hole is reduced or the groove hole is clogged, the sensor unit 106 cannot be inserted and measurement becomes impossible. Further, when the groove 108 is closed due to the rock 108b falling during measurement, there is a problem that it is difficult to collect the sensor unit 106 after the measurement.

In view of the above-mentioned problems, an object of the present invention is to easily and surely mount an elastic sensor which is used when investigating the quality of rock around a building by elastic wave velocity measurement into the hole and recovering it. A method of installing and removing a wave velocity measuring device and an elastic wave velocity measuring device.

[0009]

In order to solve the above problems, an elastic wave velocity measuring device (1) according to claim 1 judges the quality of rock mass around a building in underground civil engineering work such as a tunnel. Therefore, the elastic wave velocity measuring device measures the elastic wave velocity in the groove (40) provided in the ground, and the sensor (6) capable of measuring the elastic wave velocity is pressed against the inner wall of the groove. A leaf spring (2) for fixing the sensor in the groove by its urging force, and a leaf spring attachment member (hollow pipe 3) having both ends attached to the leaf spring and elongated in the longitudinal direction. And a plurality of slits (31) capable of exposing the sensor from a part of the outer periphery of the sensor section (10) provided therein and the sensor section being inserted into the slot and having the sensor section housed therein. Casing pipe provided (30 Characterized in that it comprises and.

According to the elastic wave velocity measuring device of the first aspect, since the casing pipe is inserted into the groove hole and the sensor portion is arranged inside the casing pipe, the periphery of the groove hole after the groove hole is excavated. It is possible to easily perform the installation and removal work of the sensor unit at the measurement point without being affected by the collapse of the rock, and to improve the efficiency of the measurement work.

As the leaf spring, for example, if a member having a property of returning to its original shape with heating or the passage of time, such as a shape memory alloy or a superelastic alloy, is used, the leaf spring is crushed in advance to be plastic. When deformed and put in the groove hole, the leaf spring can act so as to press the wall surface of the groove hole, and the sensor can be easily and surely fixed in the groove hole. That is, due to the shape restoring action of the leaf spring, a force that presses the wall surface of the groove hole from the inner side to the outer surface acts, and it is possible to obtain a pressing force of a certain level or more, so that the sensor can be easily and reliably placed in the groove hole. Can be fixed to. In addition, as the sensor,
For example, there are speedometers, accelerometers, and piezoelectric elements,
The present invention is not limited to this, and may be any as long as the elastic wave velocity can be measured.

The elastic wave velocity measuring device according to a second aspect is the elastic wave velocity measuring device according to the first aspect, wherein the sensor portion attaches both end portions of the leaf spring to the leaf spring attaching member, and at least one of them. Includes a leaf spring attachment (5) movable along the longitudinal direction of the leaf spring attachment member, and a movement control means (20) for moving the movable leaf spring attachment.

According to the elastic wave velocity measuring device of the second aspect, the same effect as that of the first aspect can be obtained, and the movement of the movable leaf spring attachment is controlled by using the movement control means. The height of the leaf spring can be arbitrarily changed, and the sensor portion can be easily and surely installed in the slot.
Also, the sensor unit can be installed at any position. Further, when the sensor fixed in the slot by the leaf spring is collected, the leaf spring can be closed by the tension thereof by moving the movable leaf spring attachment by the movement control means. Separates from the inner wall of the slot,
Since the leaf spring and the sensor are housed inside the casing pipe, the sensor portion can be easily and reliably recovered from the groove hole. As the movement control means,
For example, connect the cable to a movable leaf spring fixture,
The height of the leaf spring can be arbitrarily adjusted by moving the cable, or the movable leaf spring fixture is fixed with a pin, and this pin is connected by a cable and pulled from outside the slot. And the pin may be removed based on an electric signal sent from the outside.

A method of installing and removing an elastic wave velocity measuring device according to a third aspect is the method of installing and removing an elastic wave velocity measuring device using the elastic wave velocity measuring device according to claim 1 or 2. A casing pipe inserting step of inserting into the groove hole, a sensor portion moving step of inserting the sensor portion into the casing pipe inserted into the groove hole, and moving the sensor portion to a measurement point; At the point, the sensor provided in the sensor section is exposed from the slit of the casing pipe, the sensor section installation step of placing the sensor in close contact with the inner wall of the groove hole, and after the measurement work is completed, the sensor is installed in the casing pipe. And a sensor part removing step of removing the sensor part and the casing pipe from the slot while being housed inside.

According to the elastic wave velocity measuring apparatus installation and removal method of the third aspect, the same effect as that of the first or second aspect can be obtained, and the casing pipe is first inserted into the slot provided in the ground. After that, the sensor portion is inserted into the inside of the casing pipe. Therefore, the sensor unit can be installed at the measurement point without being affected by the collapse of the rock around the groove hole after the excavation of the groove hole. After the measurement, the sensor part is collected through the inside of the casing pipe.
It is possible to reliably collect the sensor unit without being affected by the fallen rocks inside the slot.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an elastic wave velocity measuring device according to the present invention will be described below in detail with reference to the drawings.

An elastic wave velocity measuring device 1 shown in FIGS. 1 and 2.
Is a strip-shaped leaf spring 2, a hollow pipe 3 as a leaf spring attachment member having a hollow portion 3a, to which both end portions 2a of the leaf spring 2 are attached, and a joint 4 for connecting the hollow pipe 3 in the longitudinal direction. A sensor unit 10 that is roughly configured by two leaf spring fixtures 5 that are attached to both ends 2a of the leaf spring 2 in the hollow pipe 3 and a piezoelectric element as a sensor 6 that is attached to the inner surface of the leaf spring 2. Prepare Further, it comprises a movement control means 20 for moving the leaf spring attachment 5, and a casing pipe 30 for inserting the sensor part 10 and the movement control means 20 therein. It should be noted that the sensor 6 is connected via the lead wire 7 passing through the hollow pipe 3.
And a personal computer (not shown) are connected.

The leaf spring 2 is made of a so-called superelastic alloy, for example, titanium (Ti) and nickel (N).
i) having a composition of about 50% is used. This leaf spring 22
Forms a substantially flat surface in the state before the load is applied, that is, in the normal state. Then, for example, as shown in FIG. 3, after the leaf spring 2 (solid line portion) having a height h and a length L is once loaded from above and plastically deformed by Δh (broken line portion), When the load is removed, it has a property (superelastic effect) of returning to its original shape (solid line portion) with the passage of time. By utilizing this superelastic effect, for example, as shown in FIG. 1, when the leaf spring 2 is plastically deformed in advance and then inserted into the slot 40, the restoring force of the leaf spring 2 (the original 40) by the force to return to the shape)
The leaf spring 2 is pressed against the hole wall 40a of the slot 6, so that the sensor 6 can be fixed to the hole wall 40a of the slot 40.

A shape memory alloy may be used as the leaf spring 2. In this case, a heating means such as nichrome wire is provided in the hollow portion of the casing pipe 30 as needed. Further, a normal alloy may be used for the leaf spring 2. In this case, the leaf spring 2 is inserted into the casing pipe 30 in a lowered state, and the leaf spring fixture 5 is moved at the measurement position by using the movement control means 20 described later to move the leaf spring 2. Adjust the height of
The leaf spring 2 is pressed against the hole wall 40a of the groove 40 to fix the sensor 6 to the hole wall 40a of the groove 40.

The hollow pipe 3 is, for example, a round metal pipe, and as shown in FIG. 2, its hollow portion 3a.
The lead wire 7 and the like connected to the sensor 6 can be passed therethrough, and the sensor 6 and the personal computer are connected via the lead wire 7. The hollow pipe 3 is joined to both end portions 2a of the leaf spring 2,
A member provided to support the leaf spring 2, and as long as it can be used as a leaf spring attachment member,
The cross-sectional shape is not limited to a circular shape, and may be, for example, a polygonal shape or any other shape. The length of the hollow pipe 3 can be changed as appropriate by adding the joint 4. Moreover, you may use the rod-shaped member which is not equipped with the hollow part 3a. In this case, the lead wire 7 is arranged in the hollow portion of the casing pipe 30 described later.

As shown in FIG. 1, the leaf spring 2 attachment 5 is a member for attaching both end portions 2a of the leaf spring 2 to the hollow pipe 3, one of which is fixed to the hollow pipe 3 ( The fixed leaf spring attachment 5a) is fixed to the other by a pin 21 described later, and by removing the pin 21, it is possible to move along the longitudinal direction of the hollow pipe 3 (movable leaf spring attachment). Tool 5b). Therefore, since the bending height of the leaf spring 2 can be changed by removing the pin 21 (see FIG. 5), the groove hole 40 of the sensor 6 can be changed.
It becomes easy to adjust the degree of close contact with the hole wall 40a and to collect it from the groove hole 40. The movable leaf spring mounting member 5b is not fixed by the pin 21 and is joined to the cable 22 included in the movement control means 20 described later.
It is also possible to open and close the leaf spring 2 by moving the and to arbitrarily adjust the height of the leaf spring 2.

Here, the movement control means 20 for moving the movable leaf spring attachment 5b comprises the pin 21 and the cable 22 attached to the tip of the pin 21, as shown in FIG. 4, for example. By operating the cable 22 from the outside of the groove 40, the pin 21 can be freely attached and detached, and the movable leaf spring attachment 5b is moved,
The sensor unit 10 can be installed and collected. Further, the sensor unit 10 can be installed at any position. Further, in order to accurately measure the elastic wave velocity, it is necessary to obtain a stable initial arrival output of a predetermined value or more, and for that purpose, the pressing force of the leaf spring 2 must be within an appropriate range. That is, if the pressing force of the leaf spring 2 is weak, the change in the initial output is large, and if the pressing force of the leaf spring 2 is too strong, the leaf spring 2 may be deformed. Therefore, for example, the distance between the fixed plate spring mounting member 5a and the movable plate spring mounting member 5b is expanded or contracted according to the diameter of the slot 40 to adjust the bending height of the plate spring 2. The pressing force against the hole wall is optimized so as not to be too weak or too strong to form an M shape (dent). The movable plate spring mounting member 5b may be moved integrally with the cable without being fixed by the pin 21, so that the sensor unit 10 may be installed and recovered.

When operating the cable 22 from the outside of the slot 40 as described above, for example, of both end portions of the cable 22, the end portions on the side not attached to the pins 21, that is, By winding the end of the groove 40 on the outside on the reel or the like, the cable 22 can be easily taken in and out, and the cable 22 does not get in the way.

In the leaf spring 2 shown in this embodiment,
The pressure (pressing force) is preferably within the range of 10N to 20N, and the displacement amount of the leaf spring 2 is also designed in accordance with this. The proper pressing force or the amount of leaf spring displacement is also a design matter, and it goes without saying that the proper range is changed depending on the type of the sensor 6, the shape of the groove 40, and the like. Further, the pin 21 is designed to be fixed or released by an electromagnetic method so that an electric signal can be transmitted through the groove 40.
It may be operated by sending it to the pin 21 from outside. Further, the movable leaf spring attachment 5b may be fixed to the hollow pipe 3 by means other than the pin 21.

The piezoelectric element is an element that is used as the sensor 6 and converts pressure into voltage. The size is, for example, about 3 mm square, and as the physical properties, the resonance frequency is 500 kHz, and the frequency band is 100 Hz to 1 kHz.
And so on. The piezoelectric element is fixed to the inner surface of the leaf spring 2 with an adhesive or the like. The dimensions and physical properties of the piezoelectric element are design items and can be changed as appropriate.

Further, the lead wire 7 connected to the piezoelectric element is connected to an A / D conversion board (not shown) incorporated in a personal computer (not shown), and an analog signal sent from the piezoelectric element is sent. Is converted into a digital signal by an A / D conversion board (not shown), and the digital signal is stored in a storage device (for example, a hard disk) in a personal computer (not shown). Further, a 1 M ohm resistor (not shown) is connected to the lead wire 7 as a high-pass filter for removing noise. Note that the specifications of the high-pass filter are design items and can be changed as appropriate according to the survey target, the sensor 6, and the like.

The casing pipe 30 is, for example, a round metal pipe, which is inserted into the groove 40 after the groove 40 is formed in the ground, and the sensor portion is provided in the hollow portion of the casing pipe 30. It is provided for accommodating 10 and the movement control means 20. The casing pipe 30 can be connected in the longitudinal direction by a joint (not shown),
The length can be adjusted according to the length of the slot 40 provided. A slit 31 is provided on the surface of the casing pipe 30.

The slits 31 are provided for exposing the leaf spring 2 and the sensor 6 attached to the inner surface side of the leaf spring 2 from four positions on the upper, lower, left and right sides of the casing pipe 30 and bringing them into close contact with the measurement position in the slot 40. To be Slit 31
Is set to be slightly larger than the width of the leaf spring 2, and the length of the leaf spring 2 allows the sensor 6 to move the sensor 6 into the hole wall 4 of the slot 40.
The length is set such that the leaf spring 2 and the casing pipe 30 do not interfere with each other in the state of being in close contact with 0a.

The sectional shape of the casing pipe 30 is not limited to the circular shape, and may be other than that, for example, a polygonal shape. Further, the outer diameter of the casing pipe 30 can be appropriately changed within a range in which it can be inserted into the slot 40. Further, in the above-mentioned case, the casing pipe 30 is connected over almost the entire region in the longitudinal direction of the slot 40,
In addition, the casing pipe 30 is disposed only near the measurement position inside the slot 40, and the other portion is a normal pipe having an inner diameter substantially similar to that of the casing pipe 30 and having no opening. It may be used. Further, a boring bit used when boring the slot 40 and a guide provided with slits may be used as the casing pipe 30.

In the present embodiment, the leaf spring 2
Further, the sensors 6 attached to the leaf spring 2 are arranged at four positions on the upper, lower, left and right sides of the casing pipe 30, but the numbers of the leaf springs 2 and the sensors 6 can be appropriately changed.
A plurality of sensor units 10 may be provided in the longitudinal direction of the slot 40 so that measurement can be performed at a plurality of locations in the slot 40.
Further, the sensor unit 10 is provided with an image pickup means such as a CCD camera, and the close contact state between the sensor 6 and the wall hole 40a of the groove 40 can be photographed, so that the movement can be performed while watching the photographed image. The control means 20 can be used to more accurately optimize the pressing force of the leaf spring 2.

Further, as shown in FIG. 4, a balloon-shaped gap filling member 8 is arranged between the leaf spring 2 and the hollow pipe 3, and the gap filling member 8 serves as an injection means for communicating with the outside of the slot 40. Connected to the pipe 81. A pump (not shown) pours water or air into the gap filling member 8 so that expansion and contraction of the gap filling member 8 can be freely adjusted, so that the slit 31 is introduced into the casing pipe 30. It is possible to prevent the situation in which the earth and sand enter and the earth and sand accumulate between the leaf spring 2 and the hollow pipe 3 and the leaf spring 2 and the sensor 6 cannot be stored inside the casing pipe 30.

Next, a method of installing the above-described elastic wave velocity measuring device 1 will be described. First, the casing pipe 30 is inserted into the slot 40 provided in the ground. If necessary, the casing pipe 30 is connected in the longitudinal direction by a joint to adjust the length. Then, the two leaf spring fittings 5a and 5b attached to both ends 2a of the leaf spring 2 are moved in the length direction of the leaf spring 2 to adjust the height of the corrugated leaf spring 2. At this time, the distance between the apexes of the two opposing leaf springs 2 is set to be slightly larger than the outer diameter of the casing pipe 30.

Then, a load is applied from above each leaf spring 2 to cause plastic deformation, that is, two leaf springs 2 facing each other.
The sensor unit 10 is inserted into the casing pipe 30 and is moved to the measurement point in a state where the distance between the apex portions of the above is deformed so as to be smaller than the inner diameter of the casing pipe 30. At the measurement point, the vertex portion of each leaf spring 2 in the restored state and the sensor 6 attached to the inner surface side of the vertex portion are exposed to the outside through the slit 31 provided in the casing pipe 30. The leaf spring 2 is
Since the superelasticity effect is provided as described above, the leaf spring 2 is pressed against the hole wall 40a of the groove hole 40 at the measurement point and comes into close contact therewith. In this state, the movement control means 20 finely adjusts the position of the movable leaf spring mounting member 5b, so that the sensor 6 can be brought into closer contact with the measurement location.

In this state, the velocity of the elastic wave is measured, and after the measurement is completed, first, the movement control means 20 releases the constraint of the pin 21 fixing the movable leaf spring attachment 5b. Then, the movable leaf spring attachment 5b fixed by the pin 21 is moved in a direction away from the fixed leaf spring attachment 5a, and the apex portion of the leaf spring 2 and the sensor 6 are housed inside the casing pipe 30. . After pulling out the sensor unit 10 from the casing pipe 30 in this state,
The work is completed by removing the casing pipe 30 from the slot 40. Although the method of installing and recovering the sensor unit in the state where the leaf spring is deformed in advance has been described here, the sensor unit is moved to the measurement position without deforming the leaf spring, and the movement control means is operated at the measurement position. By using it, you can adjust the height of the leaf spring, install the sensor unit,
Collection work may be performed.

According to the elastic wave velocity measuring device 1 of the present invention, the casing pipe 30 is first inserted into the groove 40 provided in the ground, and then the sensor portion 10 is provided inside the casing pipe 30. Since the arrangement is made, the sensor unit 10 can be easily installed and removed at the measurement point without being affected by rock collapse around the groove hole 40 after excavation of the groove hole 40, and the efficiency of the measurement work can be improved. Can be planned. In addition, when the sensor 6 fixed in the groove 40 by the leaf spring 2 is collected after the measurement work is completed, the movable leaf spring attachment 5b is used.
The leaf spring 2 can be closed by the tension of the leaf spring 2 when the leaf spring 2 is moved by the movement control means 20. Therefore, the leaf spring 2 is separated from the hole wall 40a of the groove hole 40, and the leaf spring 2 and the sensor 6 are housed inside the casing pipe 30, so that the sensor unit 10 can be easily and reliably passed through the casing pipe. Can be collected.

When a member having the property of returning to its original shape with heating or the passage of time is used as the leaf spring 2, if the leaf spring 2 is crushed in advance and plastically deformed and put into the slot 40, The spring 2 is the hole wall 40 of the slot 40.
Since it is possible to act so as to press a, the sensor 6 can be easily and surely fixed in the slot 40. That is, due to the shape restoring action of the leaf spring 2,
A force for pressing the hole wall 40a of the groove 40 from the inner side to the outer side works, and a pressing force of a certain level or more can be obtained, so that the sensor 6 can be easily and surely fixed in the groove 40. it can.

Further, since the piezoelectric element used as the sensor 6 is provided on the inner surface side of the leaf spring 2, the elastic wave propagated to the hole wall 40a of the groove hole 40 is applied to this piezoelectric element via the leaf spring 2. It is possible to transmit and measure the elastic wave velocity. Therefore, as compared with the accelerometer or the like used as the sensor 6 in the related art, the sensor unit 10 can be downsized, and the groove hole 40 can be made smaller, and at the same time, one groove hole 40 can be formed. A plurality of sensors 6 can be attached inside, and the measurement time of elastic wave velocity can be shortened.

[0038]

According to the elastic wave velocity measuring apparatus of the first aspect, the sensor unit is installed and removed at the measurement point without being affected by the collapse of rocks around the slot hole after the slot hole excavation. The work can be performed easily, and the efficiency of the measurement work can be improved. Moreover, the sensor can be easily and surely fixed in the slot.

According to the elastic wave velocity measuring device of the second aspect, the same effect as that of the first aspect can be obtained, the leaf spring is separated from the inner wall of the groove hole, and the leaf spring and the sensor are inside the casing pipe. The sensor portion can be easily and surely collected from the groove hole.

According to the elastic wave velocity measuring apparatus installation / removal method of the third aspect, the same effect as that of the first or second aspect can be obtained, and at the same time, after the excavation of the slot, the rock around the slot collapses. The sensor unit can be installed at the measurement point without being affected. In addition, the sensor part can be reliably collected without being affected by the fallen rocks inside the slot.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of an elastic wave velocity measuring device according to this embodiment.

FIG. 2 is a front view showing the structure of the elastic wave velocity measuring device according to the present embodiment.

FIG. 3 is a diagram showing how a leaf spring is bent when a load is applied from above.

FIG. 4 is a longitudinal sectional view showing an example of an elastic wave velocity measuring device according to the present embodiment.

FIG. 5 is a vertical cross-sectional view showing a state in which fixation by a leaf spring is released.

FIG. 6 is a vertical sectional view showing a structure of a conventional elastic wave velocity measuring device.

FIG. 7 is a vertical cross-sectional view showing a state in which rock falls in a slot.

[Explanation of symbols]

1 Elastic wave velocity measuring device 2 leaf spring 3 Leaf spring mounting member (hollow pipe) 5 Leaf spring attachment 6 sensors 10 Sensor part 20 Movement control means 30 casing pipe 31 slits 40 slots

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Claims (3)

(57) [Claims] 1. In underground civil engineering work such as tunnels,
An elastic wave velocity measuring device for measuring an elastic wave velocity in a groove provided in the ground in order to judge the quality of rock around the building, comprising a sensor capable of measuring the elastic wave velocity, and the groove hole. A sensor unit including a leaf spring that presses against the inner wall of the plate spring and fixes the sensor in the groove hole by the urging force, and both end portions of the leaf spring are attached, and a leaf spring attachment member that is long in the longitudinal direction. A casing pipe provided with a plurality of slits capable of exposing the sensor from a part of the outer periphery of the sensor pipe while being inserted into the slot and housing the sensor portion inside. Elastic wave velocity measuring device. 2. The elastic wave velocity measuring device according to claim 1, wherein the sensor portion attaches both end portions of the leaf spring to the leaf spring attachment member, and at least one of them is arranged in a longitudinal direction of the leaf spring attachment member. An elastic wave velocity measuring device comprising: a leaf spring attachment that is movable along a line; and a movement control unit that moves the movable leaf spring attachment. 3. A method for installing and removing an elastic wave velocity measuring device using the elastic wave velocity measuring device according to claim 1, comprising a casing pipe inserting step of inserting the casing pipe into the groove hole, and the groove. A sensor part moving step of inserting the sensor part into the casing pipe inserted into the hole and moving the sensor part to a measurement point, and a sensor provided in the sensor part from the slit of the casing pipe at the measurement point. The sensor part and the casing pipe in a state where the sensor is housed inside the casing pipe after the sensor part installation step and the measurement work in which the sensor is closely attached to the inner wall of the groove hole and the measurement work are completed. The method for installing and removing an elastic wave velocity measuring device, comprising: