JP3102856B2 - Elastic wave velocity measuring device and elastic wave velocity measuring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is used in an underground civil engineering work such as a tunnel to investigate the quality of rock around an object by elastic wave velocity, and is applied to a groove provided in the ground. The present invention relates to an installed elastic wave velocity measuring apparatus and an elastic wave velocity measuring method using the apparatus.

[0002]

2. Description of the Related Art Conventionally, in civil engineering work underground such as a tunnel, rock surveys for judging the quality of rock around a construction are generally performed. There is an elastic wave velocity measurement method as a rock investigation method. This elastic wave velocity measurement method is a method of analyzing elastic wave refraction phenomena due to differences in the density, rigidity, etc. of the formation, by installing a sensor on the ground surface or underground, and measuring the artificially transmitted elastic wave. It measures arrival time and the like. As a sensor installed on the ground surface or underground to measure the velocity of elastic waves, in the case of measurement on the ground surface, for example, a speedometer such as a geophone (trade name) is used. In many cases, an accelerometer that can be downsized is often used.

In order to accurately measure the elastic wave velocity, it is important that the sensor is securely fixed to a ground surface or a slot provided in the ground. In the case of measurement, for example, a hole is drilled in a bedrock with an electric drill, and a pin attached to the sensor is inserted into the hole, and then the sensor is fixed with plaster, or a hole-in anchor is driven into the hole. After that, a method of attaching a screw to the sensor and screwing and fixing the sensor to the hole-in anchor has been performed. On the other hand, in the case of underground measurement, in order to collect data in multiple directions (for example, three directions) in a narrow underground space, it is desirable to use a fixing method that is as easy as possible, and the sensor can be used. However, it is more difficult than the measurement on the ground surface because there is a restriction such as the desire to collect only.

[0004] A conventional method of fixing a sensor in the case of measuring elastic wave velocity in the ground will be described below. The fixing method shown in FIG. 7 is a method of embedding and fixing the sensor 202 together with the non-shrinkable mortar 201 in the borehole 200 (embedding method). The fixing method shown in FIG. 8 is a method of fixing using an airbag 203 to facilitate collection (airbag method). When the sensor 202 is installed, air is sent and pressed against the hole wall 200a. When collecting, the air is removed. In the fixing method shown in FIG. 9, the sensor 202 is sandwiched between mounting jigs 204, 204 and leaf springs 205, 20 are attached to the mounting jigs 204, 204.
5 is attached and fixed to the hole wall 200a by utilizing the flexibility of the leaf springs 205, 205 (leaf spring method). In this case, a piezoelectric element (not shown) may be attached to the leaf spring 205 as the sensor 202. The fixing method shown in FIG.
06 is fixed in the borehole 200 with the non-shrink mortar 201, and a jig with the sensor 202 attached to the casing 206 is inserted (casing method). In this case, if the inner diameter of the casing 206 and the outer diameter of the sensor 202 are matched, highly accurate measurement is possible.

[0005]

However, the above-described conventional method of fixing the sensor 202 underground has the following problems. That is, in the case of the embedding method, in order to measure accurately, the physical properties of the non-shrink mortar 201 and the surrounding ground must be approximated as much as possible.
It is difficult, and it is very difficult to collect the sensor 202.

[0006] In the case of the airbag method, there is a problem that the air may escape on the way and lacks certainty. Further, in the case of the leaf spring method, when the hole diameter is different from the set value or there is a hole, there is a problem that the pressing force against the hole wall 200a changes and the accuracy of the measured value is deteriorated. Was. Furthermore, in the case of the casing method, a relatively large space is required, so that there is a problem that the method may not be able to be employed depending on the place where the measurement is performed. In addition, when measurement is performed on the entire cross section of the tunnel, the number of measurement points increases, so that any of the methods has a problem that the work load is large and the cost is high.

Therefore, the present invention has been made to solve the above-mentioned problems, and it is easy and reliable to install a sensor on a hole wall in elastic wave velocity measurement, and it is easy to collect the sensor. It is an object of the present invention to provide an elastic wave velocity measuring device and an elastic wave velocity measuring method that can easily measure an elastic wave velocity.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an underground civil engineering work such as a tunnel, in which the quality of the rock around the building is determined in a slot provided in the ground. An elastic wave velocity measuring device for measuring an elastic wave velocity by using a sensor capable of measuring the elastic wave velocity and pressing the sensor against the hole wall of the slot to fix the sensor in the slot. Alloy spring made of elastic alloy and front
And a movable band for adjusting the amount of deflection of the alloy spring .

According to the first aspect of the present invention, the sensor portion is fixed in the groove by the alloy spring. At this time, the alloy spring of the sensor portion is plastically deformed by being crushed in advance and put into the groove. Since the alloy spring has the property of returning to its original shape with the passage of time, the alloy spring can act so as to press against the hole wall, so that the sensor portion can be easily and reliably placed in the slot. Can be fixed to That is, due to the restoring action of the shape of the superelastic alloy, which is an alloy spring, a force that presses the hole wall from the inside to the outside acts, and a pressing force of a certain level or more can be obtained. It can be easily and reliably fixed in the hole, and can be easily pulled out from the slot. Also, the bending of the alloy spring due to the movable band
The amount can be adjusted to optimize the pressing force against the hole wall.
It is.

[0010] Here, the superelastic alloy is an alloy obtained by plastically deforming a given specific shape, which has a property of undergoing a phase transformation over time without heating and returning to the original shape. For example, there are a Ti-Ni-based alloy and a Cu-Al-Ni-based alloy.

Further, for example, when a shape memory alloy is used as the alloy spring, it is not necessary to separately provide a heating means for heating the alloy spring when the temperature in the slot is higher than the transformation temperature of the shape memory alloy. When low, it is necessary. On the other hand, in the present invention, since the superelastic alloy is used, the superelastic alloy can be used regardless of the temperature in the slot without a heating means. Examples of the sensor include a speedometer, an accelerometer, and a piezoelectric element. However, the sensor is not limited to this, and any sensor may be used as long as it can measure an elastic wave velocity.

According to a second aspect of the present invention, in an underground civil engineering work such as a tunnel, an elastic wave velocity is measured by measuring an elastic wave velocity in a slot provided in the ground to determine the quality of rock around the building. A measuring device, comprising: a sensor made of a piezoelectric element capable of measuring the elastic wave velocity; an alloy spring that presses against a hole wall of the slot to fix the sensor in the slot; and a deflection amount of the alloy spring. Adjustable movable band
The alloy spring is an alloy having a property of returning its shape to its original state by heating or without heating after applying plastic deformation within a certain range, The sensor is attached to an inner surface of the alloy spring.

According to the second aspect of the present invention, the sensor portion is fixed in the slot by the alloy spring. At this time, if the alloy spring of the sensor portion is crushed in advance and plastically deformed, and then inserted into the slot. Since the alloy spring has the property of returning to its original shape over time or over time, the alloy spring can act to press the hole wall, and the sensor part can be easily placed in the slot. And it can be fixed securely. In addition, since the piezoelectric element used as a sensor is provided on the inner surface side of the alloy spring, the elastic wave propagated to the hole wall of the slot is transmitted to this piezoelectric element via the alloy spring to measure the elastic wave velocity You can do it. Therefore, as compared with an accelerometer or the like conventionally used as a sensor, the sensor unit can be downsized, the slot can be made smaller, and a plurality of slots can be provided in one slot. A sensor can be attached and the measurement time of elastic wave velocity can be shortened. Ma
The movable band can adjust the amount of bending of the alloy spring.
Therefore, the pressing force against the hole wall can be optimized.

Here, the size, physical properties, and the like of the piezoelectric element are design items, and can be appropriately changed according to the measurement environment. An alloy having the property of restoring its shape to its original state with or without heating after plastic deformation within a certain range is a so-called shape memory alloy or superelastic alloy. A shape memory alloy is an alloy obtained by plastically deforming a given shape in a predetermined shape, and having a property of returning to an original shape by phase transformation at the time of heating, for example, a Ti-Ni alloy or , Cu-Al-Ni alloys and the like. Claim 3
The invention described above is an elastic wave velocity meter according to claim 1 or 2.
An elastic wave velocity measuring method using a measuring device, wherein the alloy
The outer diameter of the sensor part is reduced by applying plastic deformation to the spring.
A first step of positioning the sensor section in a predetermined position in the slot.
And a restoring force of the alloy spring.
The third process of fixing the alloy spring by pressing it against the hole wall of the slot
, And is characterized by having. Claim 3
According to the invention described above, the same as the invention of claim 1 or 2 is provided.
The effect is obtained.

According to a fourth aspect of the present invention, there is provided an elastic wave velocity measuring method using the elastic wave velocity measuring device according to the first or second aspect, wherein the first method comprises the steps of: A first step of inserting and installing one or more of the sensor units in the first slot before forming the second slot after forming the slot of A second slot is formed by using a drilling unit, and the elastic wave velocity generated when the drilling unit drills is reduced by one or a plurality of the elastic waves installed in the first slot. A second step of measuring with a sensor unit, and then collecting one or more of the sensor units from the first slot and collecting one or more of the sensor units in the second slot And a third step of inserting and installing the sensor section.

According to the fourth aspect of the present invention, in the first step, after the rock is drilled by the drilling means to form the first slot and before the second slot is formed. And one or more sensor portions are inserted and installed in the first slot, and then, in a second step, the second slot is formed by the drilling means, The velocity of elastic waves generated when drilling rock is measured by one or a plurality of sensor units installed in the slot, and then, in the third step, one of the one from the first slot is measured. Alternatively, a plurality of sensor units are collected, and one or a plurality of collected sensor units are inserted and installed in the second slot. Therefore, it is possible to measure the elastic wave velocity using the elastic wave generated in the drilling work at the same time as drilling the slot for the survey, and it is not necessary to provide a separate elastic wave generating means, and the cost can be reduced. Also, the elastic wave measurement time can be shortened.

For example, in the case of a tunnel, after the third step is performed, the second step and the third step are repeated for the entire cross section of the tunnel, so that the distribution of elastic wave velocities surrounding the entire section of the tunnel is investigated. It can be performed efficiently and at low cost, and by analyzing this distribution, it is possible to clarify the physical properties of the ground around the tunnel.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an elastic wave velocity measuring apparatus and an elastic wave velocity measuring method according to the present invention will be described below in detail with reference to the drawings. First, the configuration of the elastic wave velocity measuring device will be described with reference to FIGS. FIG. 1 is a side view of a borehole when a sensor unit of the elastic wave velocity measuring device according to the present invention is installed on a hole wall of the borehole.
FIG.

The elastic wave velocity measuring device 1 shown in FIGS. 1 and 2
Is a hollow pipe 11 having a hollow portion 11a, a joint 12 connecting the hollow pipe 11, and the hollow pipe 11
The movable band 13 is provided so as to cover the periphery of a part of the movable pipe 13 and is movable along the longitudinal direction of the hollow pipe 11.
13, alloy springs 14, 14 having both ends coupled to two adjacent movable bands 13, 13, and piezoelectric elements 15, 15, etc., serving as sensors attached to inner surfaces of the alloy springs 14, 14. Having a sensor unit 10
A personal computer (not shown) connected to the piezoelectric elements 15 and 15 via lead wires 16 and 16
It is roughly configured from the ones with the addition.

The hollow pipe 11 is, for example, a square metal pipe, and the lead wires 16, 1 connected to the piezoelectric elements 15, 15 in the hollow portion 11a (FIG. 2).
6 and so on. The shape of the hollow pipe 11 may be a circular shape other than a square shape, or may be other shapes. The outer diameter of the hollow pipe 11 may be any as long as it can enter the borehole 100, and the length can be changed as appropriate.

The movable bands 13, 13 are members for fixing both ends of the alloy springs 14, 14 to the hollow pipe 11. The movable bands 13, 13 are made of, for example, rubber or the like, and can move along the longitudinal direction of the hollow pipe 11. Thereby, for example, the width of the adjacent movable bands 13 and 13 can be expanded and contracted in accordance with the diameter of the slot 100, and the height of the bending of the alloy spring 14 is adjusted to adjust the width of the hole. The wall 100a is optimized so that the pressing force of the wall 100a is not too weak or too strong and does not have an M-shaped shape. Note that the movable band 13 and the hollow pipe 11 may be fixed by screws or the like in addition to the rubber.

The alloy springs 14, 14 are made of a so-called superelastic alloy, and have a composition of about 50% titanium (Ti) and nickel (Ni), for example. For example, as shown in FIG. 3, the alloy springs 14 and 14 are formed by applying a load from above to the alloy spring 14 having a height h (solid line portion) and plastically deforming the alloy spring 14 by Δh (broken line portion). ),
When the load is removed, it has the property of returning to the original shape (solid line portion) over time (superelastic effect). By utilizing this superelastic effect, for example, as shown in FIG. 1, when the alloy spring 14 is plastically deformed in advance and then inserted into the bore hole 100, the restoring force of the alloy spring 14 (the original shape) Force to return to the borehole 1
00, the alloy spring 14 is pressed against the hole wall 100a of the bore hole 100.
0a.

The hole wall 10 of the bore hole 100
The pressing force of the alloy spring 14 pressing on 0a will be described with reference to FIGS. FIG. 5 is a scatter diagram showing the relationship between the displacement of the alloy spring and the pressing force.
“○” indicates that the distance between the movable bands L = 6 cm, Δh =
1.6 cm, data of alloy spring width W = 10 mm, “□” indicates L = 6 cm, Δh = 1.8 cm, W
= 10mm, "●" means L = 6cm, Δh = 2.0c
m, W = 10 mm, “△” means L = 7 cm, Δh = 2.
The data when 0 cm and W = 10 mm are shown. FIG. 6 shows that “●” has L = 6 cm, Δh = 2.0 cm,
FIG. 9 is a scatter diagram showing the relationship between the pressure of the alloy spring applied to the hole wall and the initial output when W = 10 mm. As shown in FIG. 5, in any case, the gradient of the change in the pressing force is large where the displacement of the alloy spring 14 is small, and the change in the pressing force becomes gentle as the displacement increases. Here, in order to accurately measure the elastic wave velocity,
It is necessary to obtain a stable initial arrival output equal to or higher than a predetermined value,
For this purpose, the pressing force of the alloy spring 14 must be within an appropriate range. That is, when the pressing force of the alloy spring 14 is weak, the change in the initial attained output is large, and
If the pressing force is too strong, the alloy spring 14 may be deformed. Therefore, in the alloy spring 14 shown in the present embodiment, as shown in FIG. 6, the pressure (pressing force) must be in the range of 10N to 20N. For that purpose, the range of the displacement amount of the alloy spring 14 must be a range in which the pressure (pressing force) falls within the range of 10N to 20N. Specifically, as shown in FIG. 5, the displacement amount is preferably about 2 mm to 6 mm, and as the dimensional condition of the alloy spring 14, the condition of “●” is pressed to a higher displacement than other conditions. It is desirable because it satisfies the optimal range of force. The appropriate pressing force or displacement is also a matter of design, and the appropriate range is changed depending on the type of sensor, the shape of the borehole, and the like.

The piezoelectric element 15 is an element for converting pressure into voltage. The size is, for example, about 3 mm square, and the physical properties include a resonance frequency of 500 kHz and a frequency band of 100 Hz to 1 kHz. The piezoelectric element 15 is fixed to the inner surface of the alloy spring 14 with an adhesive or the like. The above dimensions and physical properties are design items and can be changed as appropriate.

The lead 16 connected to the piezoelectric element 15 is connected to a personal computer (not shown).
The analog signal sent from the piezoelectric element 15 is connected to an A / D conversion board (not shown) incorporated in the
The digital signal is converted into a digital signal by 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). The lead 16 has a 1M high-pass filter for removing noise.
An ohmic resistor (not shown) is connected. Note that the specifications of the high-pass filter are design items, and can be appropriately changed according to the investigation target, the sensor, and the like.

Further, as shown in the sectional view of the tunnel showing the arrangement of boreholes A to I provided for drilling the rock around the tunnel 50 shown in FIG.
And the movable bands 13 and 13 and the alloy springs 14 and
14, and the piezoelectric elements 15, 15 as one unit,
The unit in which several units are connected by the joint 12 can be installed in the borehole 100 as the sensor unit 10.

Next, the operation and effect of the elastic wave velocity measuring device according to the present invention will be described. The sensor part 10 is fixed in the borehole 100 by using the alloy spring 14 as the sensor fixing member having the above configuration.
When the alloy spring 14 of the sensor unit 10 is crushed in advance and plastically deformed and put into the bore hole 100 (slot), the alloy spring 14 has a property of returning to the original shape over time. Can press the hole wall 100a so that the sensor unit 10 can be easily and reliably fixed in the borehole 100. That is, by the restoring action of the shape of the alloy spring 14, a force for pressing the hole wall 100a from the inside to the outside acts, and a pressing force of a certain level or more can be obtained.
It can be easily and reliably fixed in the inside, and can be easily pulled out of the bore hole 100.

Further, since the piezoelectric element 15 used as a sensor is provided on the inner surface side of the alloy spring 14, the elastic wave propagated to the hole wall 100a of the bore hole 100 is applied to the piezoelectric element 15 via the alloy spring 14. It can be transmitted to measure the elastic wave velocity. Therefore, as compared with an accelerometer or the like conventionally used as a sensor, the sensor unit 1
0 can be made smaller, the borehole 100 can be made smaller, and a plurality of (for example, three) sensors can be mounted in one borehole 100, and the elastic wave velocity can be reduced. Measurement time can be shortened.

Next, a method of measuring the elastic wave velocity of the rock around the tunnel 50 using the elastic wave velocity measuring device 1 will be described with reference to FIG. First, after the rock is drilled with a wheel jumbo (not shown) as a drilling means to form a borehole A as a first slot, the borehole is formed before forming a borehole B as a second slot. A, the sensor unit 10 of the elastic wave velocity measuring device 1
Is inserted and installed (first step).

Next, a borehole B is formed using the wheel jumbo (not shown), and an elastic wave generated when the wheel jumbo (not shown) drills a rock is applied to the piezoelectric element 15 of the sensor unit 10. Is captured as an analog signal through the alloy spring 14, an analog signal generated based on the elastic wave is input to a personal computer (not shown) through a lead wire 16, and the input analog signal is input to the personal computer (not shown). The digital signal is converted into a digital signal by an A / D converter (not shown) in the (omitted), and then stored in a storage device (not shown) (second step). Next, the sensor unit 10 is collected from the borehole A, and the sensor unit is inserted and installed in the borehole B (third step).

A borehole C was formed using the wheel jumbo (not shown), and an elastic wave generated when the wheel jumbo (not shown) drilled rock was installed in the borehole B. The piezoelectric element 15 of the sensor section 10 captures an analog signal via the alloy spring 14 as an analog signal, and an analog signal generated based on the elastic wave is input to a personal computer (not shown) through a lead 16 and is input. A / D in a personal computer (not shown)
The signal is converted into a digital signal by a converter (not shown) and then stored in a storage device (not shown).

As described above, by repeating the second step and the third step sequentially, it is possible to measure the elastic wave velocities in the bore holes C to I. More specifically, for example, one unit of the sensor unit 10 is about 5
The sensor unit 10 is made of 0 cm, and several units are connected to form a long sensor unit 10 of several meters. If the sensor unit 10 has a length of 4 m, it is possible to measure a total of 32 in eight cross-sections, four in four directions in one cross section. Then, the sensor unit 10 is installed in the borehole B in a state as shown in FIG. A lead wire 16 extending from the sensor section 10 is connected to an A / D conversion board (not shown) incorporated in a personal computer (not shown), and the piezoelectric element 1 of the sensor section 10 is connected.
The analog signal generated by 5 is digitally converted and stored in a personal computer (not shown). The time required for attaching and detaching the sensor unit 10 can be reduced to 15 minutes or less.

According to the elastic wave velocity measuring method described above, the elastic wave velocity can be measured by utilizing the elastic wave generated at the time of drilling the borehole 100 for investigation, and the elastic wave velocity can be measured separately. Wave generation means (for example, primer,
It is not necessary to provide an explosive or a hammer), so that the cost can be reduced and the elastic wave measurement time can be shortened. For example, in the case of the tunnel 50, the third
After performing the step, the second step and the third step are performed in the tunnel 50.
It is possible to carry out an investigation of the distribution of elastic wave velocities surrounding the entire cross section of the tunnel efficiently and at low cost by repeating the entire cross section of the tunnel. Physical properties can be clarified.

In the above embodiment, a superelastic alloy is used as the sensor fixing member. However, a shape memory alloy may be used. In this case, a heating means for heating the sensor fixing member may need to be separately provided. As the heating means, for example, a nichrome wire or the like may be arranged in the hollow portion of the hollow pipe 11, or a means for directly heating the hollow pipe 11 may be used.

[0035]

According to the first aspect of the present invention, the sensor portion is fixed in the slot by the alloy spring. At this time, the alloy spring of the sensor portion is crushed in advance and is plastically deformed, so that the alloy spring is formed in the slot. When inserted, the alloy spring has the property of returning to its original shape over time, so that the alloy spring can act to press the hole wall, and the elastic wave velocity measuring device Can be easily and reliably fixed, and can be easily pulled out from the inside of the slot. In addition, the amount of bending of the alloy spring is reduced by the movable band.
Adjustable to optimize the pressing force against the hole wall
You.

According to the second aspect of the present invention, the sensor portion is fixed in the slot by the alloy spring. At this time, the alloy spring of the sensor portion is plastically deformed by being crushed in advance and put into the slot. Since the alloy spring has the property of returning to its original shape over time or over time, the alloy spring can act to press the hole wall, and the sensor part can be easily placed in the slot. And it can be fixed securely. In addition, since the piezoelectric element used as a sensor is provided on the inner surface side of the alloy spring, the elastic wave propagated to the hole wall of the slot is transmitted to this piezoelectric element via the alloy spring to measure the elastic wave velocity You can do it. Therefore, as compared with an accelerometer or the like conventionally used as a sensor, the sensor unit can be downsized, the slot can be made smaller, and a plurality of slots can be provided in one slot. A sensor can be attached and the measurement time of elastic wave velocity can be shortened. Claim
According to the invention described in claim 3, the invention described in claim 1 or 2 and
Similar effects can be obtained.

According to the fourth aspect of the present invention, the first step
The rock is drilled by the drilling means,
After the formation of the first slot and before the formation of the second slot,
One or more sensor parts are inserted and installed in the slot
Then, in the second step, the second step is performed by the drilling means.
2 slots are formed and drilling means drills rock
The velocity of the elastic wave generated at the time of
Or it is measured by a plurality of sensor units, and then the third
One or more sensors from the first slot depending on the process
One or more of the parts collected and recovered in the second slot
The sensor units are inserted and installed. Therefore, the survey
The elastic waves generated in the drilling work at the same time
It will also be possible to measure elastic wave velocity using
It is not necessary to provide an elastic wave generating means, and cost reduction can be achieved.
At the same time, the elastic wave measurement time can be shortened.

[Brief description of the drawings]

FIG. 1 is a side view of a borehole when a sensor unit of the elastic wave velocity measuring device according to the present invention is installed on a hole wall of the borehole.

FIG. 2 is a front view of a borehole when a sensor unit of the elastic wave velocity measuring device according to the present invention is installed on a hole wall of the borehole.

FIG. 3 is a side view of the alloy spring according to the present invention.

FIG. 4 is a sectional view of a tunnel showing an arrangement of boreholes provided for drilling rock around the tunnel.

FIG. 5 is a scatter diagram showing the relationship between the displacement of the alloy spring and the pressing force.

FIG. 6: L = 7 cm, Δh = 2.0 cm, W = 10 mm
FIG. 3 is a scatter diagram showing the relationship between the pressure of the alloy spring applied to the hole wall and the initial output.

FIG. 7 is a cross-sectional side view of a borehole schematically showing a method of embedding and fixing a sensor together with a non-shrinkable mortar in the borehole.

FIG. 8 is a cross-sectional side view of a borehole schematically showing a method of fixing to a hole wall using an airbag.

FIG. 9 is a cross-sectional side view of a borehole schematically illustrating a method of fixing to a hole wall using a leaf spring.

FIG. 10 is a cross-sectional side view of a borehole schematically illustrating a method of fixing to a hole wall using a steel casing.

[Description of Signs] 1 elastic wave velocity measuring device 10 sensor unit 14 alloy spring (sensor fixing member) 15 piezoelectric element (sensor) 100 bore hole (slot) 100a hole wall

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsuo Hirata 14-17 Okada-cho, Kumamoto-shi, Kumamoto (72) Inventor Katsuko Kaneko 17-1-22 Minami 9-Jo Nishi, Chuo-ku, Sapporo, Hokkaido 22nd Article 29 Chateau 402 (72) Inventor Kiyoshi Yamauchi 6-7-1, Koriyama, Taishiro-ku, Sendai City, Miyagi Prefecture Tokin Corporation Electronic Materials Division (56) References JP-A-57-192640 (JP, A) JP-A Sho 62-684 (JP, A) JP-A-60-53234 (JP, A) JP-A-62-108182 (JP, A) JP-A 52-26601 (JP, U) JP-A 4-134372 (JP, A) U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01H 5/00 E21D 9/00 G01V 1/00

Claims (4)

(57) [Claims] 1. An elastic wave velocity measuring device for measuring the quality of rock around an object by measuring the elastic wave velocity in a groove provided in the ground in an underground civil engineering work such as a tunnel, A sensor capable of measuring the elastic wave velocity and an alloy spring made of a superelastic alloy for fixing the sensor in the slot by pressing against the hole wall of the slot, and a movable band for adjusting the amount of deflection of the alloy spring And an elastic wave velocity measuring device having a sensor unit having the following. 2. An elastic wave velocity measuring device for measuring the quality of rock around a construction object by measuring an elastic wave velocity in a groove provided in the ground in an underground civil engineering work such as a tunnel, A sensor made of a piezoelectric element capable of measuring the elastic wave velocity and an alloy spring that presses against the hole wall of the slot to fix the sensor in the slot, and a movable band that adjusts the amount of deflection of the alloy spring. The alloy spring is an alloy having a property of returning its shape to an original state by heating or without heating after applying plastic deformation within a certain range, and Is attached to the inner surface of said alloy spring, The elastic wave velocity measuring device characterized by the above-mentioned. 3. The elastic wave velocity according to claim 1 or 2.
An elastic wave velocity measuring method using a measuring device, Plastic deformation of the alloy spring is applied to the outside of the sensor section.
A first step of reducing the diameter, A second step of inserting the sensor section into a predetermined position in the slot;
Process and The alloy spring is pressed against the hole wall of the slot by the restoring force of the alloy spring.
A third step of attaching and fixing; An elastic wave velocity measuring method comprising: 4. An elastic wave velocity measuring method using the elastic wave velocity measuring device according to claim 1, wherein the first groove is formed using a drilling means for drilling a rock. ,
A first step of inserting and installing one or more of the sensor units in the first slot before forming the second slot; and A second slot is formed, and an elastic wave velocity generated when the drilling unit drills is measured by one or a plurality of the sensor units installed in the first slot. Step 2, and then, collecting one or more of the sensor units from the first slot and inserting one or more of the sensor units collected into the second slot. And a third step of installing the elastic wave velocity.