JP5900695B1 - Embedded state evaluation method and embedded state evaluation apparatus used therefor - Google Patents

Abstract

Provided is an embedded state evaluation method capable of evaluating a corrosion state or the like of a metal embedded material at a boundary portion between an embedded layer and a metal embedded material in a nondestructive manner. An embedded state evaluation method includes a transmitting unit that transmits an ultrasonic wave on the outer surface of a metal pipe, and a receiving unit that receives the ultrasonic wave on the surface of a concrete layer. And measuring the shortest propagation time of the received ultrasonic wave and evaluating the embedded state of the evaluation target part based on the difference between the actual measurement times of the healthy part and the evaluation target part. [Selection] Figure 2

Description

  The present invention relates to a buried state evaluation method for evaluating a buried state of a buried material, and a buried material corrosion state evaluation apparatus used therefor.

  Conventionally, when a metal burying material made of a metal tube such as a sign post, a street light post, a guard rail post, or a curve mirror post is embedded in an embedded layer made of a concrete layer, for example, Work to confirm the corrosion state has been performed. That is, it has been practiced to expose the metal pipe that has been buried by excavating and removing the concrete layer, performing a visual inspection, repairing as necessary, and then placing the concrete layer for curing.

  However, even if repairs are not required, the concrete layer is excavated and removed, and after inspection, it is expensive (and backfilled), it takes time for the survey, and in some cases it occupies a large road. Therefore, it was necessary to regulate lanes.

  Therefore, in recent years, ultrasonic measurement that can be evaluated in a non-destructive state without excavating the buried layer has been performed. As an evaluation method of the embedded state by ultrasonic measurement, for example, an ultrasonic receiver that receives an SH wave and an ultrasonic transmitter that transmits an SH wave are brought into contact with an exposed surface of a partially embedded cylindrical structure. A method for detecting a defect in a cylindrical structure is disclosed in which the position and size of the defect in the cylindrical structure are detected by closely contacting a medium and analyzing a pattern of an SH wave received by the receiver ( For example, see Patent Document 1.)

  Further, a post provided with a vertical deep touch element that enters a P wave inside the post, and a first oblique deep touch element that is arranged close to the vertical deep touch element and that receives an SH wave inside the post. A road boundary investigation system has already been disclosed (see, for example, Patent Document 2).

JP 2005-156333 A Utility Model Registration No. 3198840

  However, the configurations disclosed in Patent Documents 1 and 2 perform measurement by a so-called ultrasonic pulse reflection method. For example, a boundary portion with a concrete layer surface at which a metal pipe is exposed (hereinafter referred to as a road surface boundary portion). However, when the metal tube is strongly restrained by the compressive stress from the concrete layer, there is a problem that a reflected wave due to restraint is picked up at the time of ultrasonic measurement. Furthermore, when it is determined that the ultrasonic measurement is impossible, there is a problem that the concrete layer is excavated and removed for visual inspection, and as a result, the ultrasonic measurement itself is wasted.

  Therefore, the present invention is a non-destructive buried state evaluation capable of evaluating the corrosion state of the metal buried material or the non-attached state between the metal buried material and the buried layer at the boundary portion between the buried layer and the metal buried material. It is an object of the present invention to provide a method and an embedded state evaluation apparatus used therefor.

In the present invention, a transmitter for transmitting ultrasonic waves is disposed on either the outer surface of a metal burying material partially embedded in the buried layer or the surface of the buried layer, and the ultrasonic wave is placed on the other side. An embedded state evaluation method for evaluating a corrosion state of a metal embedded material or a non-attached state between a metal embedded material and an embedded layer at a boundary portion between the embedded layer and the metal embedded material Because
Measuring the time taken when the ultrasonic wave propagates from the transmitter to the receiver at the shortest propagation distance in the healthy part; and
The measurement time is the healthy part actual measurement time Tm.
(Tm = Y / Cm + X / Cc Y: distance of metal burying material portion X: distance of buried layer portion Cm: sound velocity of metal burying material Cc: sound velocity of buried layer)
age,
It was calculated on the assumption that the ultrasonic wave propagated from the transmitting part to the receiving part at the sound part over the sound part actual measurement time Tm only at the sound velocity of either the metal burying material or the buried layer. Healthy part virtual propagation distance Wm which is a virtual propagation distance
(Wm = Y + αX α = Cc / Cm in the case of the sound velocity of the metal buried material
(Sound velocity of buried layer Wm = βY + X β = Cm / Cc)
A process of identifying
A step of measuring the time taken when an ultrasonic wave propagates from the transmitter to the receiver in the shortest propagation distance in the evaluation target part which is a part where the embedded state is to be evaluated;
The measurement time in the evaluation target part is set as the evaluation target part actual measurement time Tf, and the evaluation target part virtual time is based on the evaluation target part actual measurement time Tf, the healthy part actual measurement time Tm, and the healthy part virtual propagation distance Wm. Propagation distance Wf
(Wf = (Tf / Tm) × Wm)
A process of identifying
Evaluating the embedded state of the evaluation target part based on the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm;
It is an embedded state evaluation method characterized by having.

  Here, the inventor used the ultrasonic transmission method to cause a non-attached state in which a gap is formed between the metal buried material and the buried layer at the road surface boundary portion, or corrosion occurs in the metal buried material. In this case, it has been considered that the presence or absence of corrosion or corrosion can be evaluated from the difference in the propagation time of ultrasonic waves by utilizing the fact that ultrasonic waves travel around the non-bonded and corroded parts.

  In such a configuration, it is not necessary to excavate the buried layer, and the embedded state of the embedded metal embedded material that cannot be visually observed can be evaluated nondestructively. Then, an ultrasonic wave transmission unit is arranged in one of the metal burying material and the buried layer, and a reception unit for receiving the ultrasonic wave is arranged in the other, and the virtual propagation specified by the propagation time of the ultrasonic wave Since it is for evaluating the presence or absence of corrosion or corrosion from the distance, the evaluation can be performed regardless of the magnitude of the compressive stress received by the metal burying material. In addition, since the presence or absence of corrosion or corrosion can be accurately evaluated numerically by the difference in the virtual propagation distance specified from the propagation time of the ultrasonic wave, the evaluation method is excellent in recordability and objectivity. Furthermore, since the corrosion state is evaluated by comparing the healthy part with the evaluation target part, there is also an advantage that a guarantee is easily obtained for the evaluation result indicating that the sound part is healthy. For example, when the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm exceeds a predetermined threshold, it is evaluated that there is corrosion or non-sticking, or the metal burying It can be evaluated that the evaluation target part of the material should be repaired.

  In addition, when there is a non-attached state where a gap is generated between the metal burying material and the buried layer at the road surface boundary, rainwater or the like flows into the gap to corrode the metal burying material. Therefore, appropriate repair is required not only in the corrosion state of the metal burying material but also in the non-attached state, but in the embedded state evaluation method of the present invention, Since it is possible to evaluate not only corrosion but also non-attachment state, it is a buried state evaluation method that is very suitable for determining whether or not repair is necessary.

In the above configuration, when the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm exceeds a predetermined threshold, a plurality of evaluation target parts are set. Identifying the width H along the circumferential direction of the metallic buried material in the non-propagating part consisting of a corroded part or a non-attached part in the boundary part between the metallic buried material and the buried layer;
Furthermore, the evaluation target part virtual propagation distance Wf specified by setting the intermediate point of the width H on the shortest path between the transmission part and the reception part,
Wh = √ (Y ² + (H / 2) ² ) + α√ (X ² + (H / 2) ² )
Or Wh = β√ (Y ² + (H / 2) ² ) + √ (X ² + (H / 2) ² )
Non-propagating part width direction virtual propagation distance Wh calculated by:
And a method of evaluating the depth D of the non-propagating part is proposed.

In this case, Wf = Wh
Then, the depth from the road surface boundary part of a non-propagation part can be evaluated by including the process of evaluating that the depth D of the said non-propagation part is larger than the said width | variety H.

Wf <Wh
If,
Wf = Y + α√ (X ² + D ² )
Or Wf = βY + √ (X ² + D ² )
Further, by including the step of specifying the depth D of the non-propagating portion, the depth D from the road surface boundary portion of the non-propagating portion can be specified.

Further, the present invention is an embedded state evaluation apparatus used in the embedded state evaluation method,
A transmitter that transmits ultrasonic waves;
A receiving unit for receiving the ultrasonic wave;
In the sound part, the measurement time taken when the ultrasonic wave propagates from the transmitter part to the receiver part with the shortest propagation distance is the sound part actual measurement time Tm.
(Tm = Y / Cm + X / Cc Y: distance of metal burying material portion X: distance of buried layer portion Cm: sound velocity of metal burying material Cc: sound velocity of buried layer)
age,
It was calculated on the assumption that the ultrasonic wave propagated from the transmitting part to the receiving part at the sound part over the sound part actual measurement time Tm only at the sound velocity of either the metal burying material or the buried layer. Healthy part virtual propagation distance Wm which is a virtual propagation distance
(Wm = Y + αX α = Cc / Cm in the case of the sound velocity of the metal buried material
(Sound velocity of buried layer Wm = βY + X β = Cm / Cc)
Sound part virtual propagation distance specifying means for specifying
The measurement time taken when the ultrasonic wave propagates from the transmitting unit to the receiving unit with the shortest propagation distance in the evaluation target part that is the part for which the embedded state is to be evaluated is defined as the evaluation target part actual measurement time Tf, and the evaluation target part Based on the actual measurement time Tf, the healthy part actual measurement time Tm, and the healthy part virtual propagation distance Wm, the evaluation target part virtual propagation distance Wf
(Wf = (Tf / Tm) × Wm)
Evaluation target part virtual propagation distance specifying means for specifying,
It is an embedded state evaluation apparatus characterized by including.

  By setting it as this structure, the corrosion state and non-sticking state of a metal embedment material can be evaluated quickly and accurately.

Furthermore, the present invention provides a transmitter for transmitting ultrasonic waves on either the outer surface of the buried material partially embedded in the buried layer or the surface of the buried layer, and the ultrasonic wave is transmitted to the other. An embedded state evaluation method for arranging a receiving unit to receive and evaluating a non-attached state between an embedded material and an embedded layer at a boundary portion between the embedded layer and the embedded material,
Measuring the time taken when the ultrasonic wave propagates from the transmitter to the receiver at the shortest propagation distance in the healthy part; and
The measurement time is the healthy part actual measurement time Tm.
(Tm = Y / Cm + X / Cc Y: distance of the buried material portion X: distance of the buried layer portion Cm: sound velocity of the buried material Cc: sound velocity of the buried layer)
age,
The hypothetical wave calculated on the assumption that the ultrasonic wave propagated from the transmitting part to the receiving part over the sound part actual measurement time Tm at only one sound speed of the buried material and the buried layer in the healthy part. Healthy part virtual propagation distance Wm which is propagation distance
(Wm = Y + αX α = Cc / Cm when the sound velocity of the buried material is used.
(Sound velocity of buried layer Wm = βY + X β = Cm / Cc)
A process of identifying
Measuring the time taken when the ultrasonic wave propagates from the transmitting unit to the receiving unit with the shortest propagation distance in the evaluation target unit, which is a portion where the non-attachment state is to be evaluated, and
The measurement time in the evaluation target part is set as the evaluation target part actual measurement time Tf, and the evaluation target part virtual time is based on the evaluation target part actual measurement time Tf, the healthy part actual measurement time Tm, and the healthy part virtual propagation distance Wm. Propagation distance Wf
(Wf = (Tf / Tm) × Wm)
A process of identifying
Evaluating the embedded state of the evaluation target part based on the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm;
It is an embedded state evaluation method characterized by having.

  In such a configuration, the non-attached state at the boundary between the surface of the buried layer and the buried material can be evaluated in a non-destructive state without excavating and removing the buried layer.

  The embedded state evaluation method according to the present invention is a non-destructive method for evaluating a corrosion state of a metal embedded material or a non-bonded state between a metal embedded material and an embedded layer at a boundary portion between the embedded layer and the metal embedded material. There is an effect that can.

  Moreover, the embedded state evaluation apparatus according to the present invention has an effect that can accurately evaluate the corrosion state and the non-attached state of the metal embedded material.

  The embedded state evaluation method according to the present invention has an effect that the non-attached state between the embedded material and the embedded layer can be evaluated easily and quickly.

(A) is explanatory drawing which shows the state which an ultrasonic wave propagates from the transmission part arrange | positioned in the metal pipe in the healthy part to the receiving part arrange | positioned in a concrete layer, (b) is explanatory drawing which shows the display aspect of a monitor It is. (A) is explanatory drawing which shows the state which an ultrasonic wave propagates from the transmission part arrange | positioned in a metal pipe to the receiving part arrange | positioned in a concrete layer in the part with a non-propagation part of the depth D in a metal pipe, b) is an explanatory view showing a display mode of a monitor. (A) is explanatory drawing which shows the state which an ultrasonic wave propagates from the transmission part arrange | positioned in a metal pipe to the receiving part arrange | positioned in a concrete layer in the part with a non-propagation part of width H in a metal pipe, ) Is an explanatory diagram in which the aa plane and the bb plane of (a) are displayed in succession. It is explanatory drawing which shows the display mode of a monitor. It is explanatory drawing which shows the state which an ultrasonic wave propagates from the transmission part arrange | positioned in the metal pipe to the receiving part arrange | positioned in a concrete layer in the part with the non-propagation part where the depth D is larger than the width H. 5A is an explanatory diagram showing a display mode of the monitor at the I position, and FIG. 5B is an explanatory diagram showing a display mode of the monitor at the II position. It is explanatory drawing which shows the state which an ultrasonic wave propagates from the transmission part arrange | positioned in the metal pipe to the receiving part arrange | positioned in a concrete layer in the part with the non-propagation part whose width H is larger than the depth D. FIG. 7A is an explanatory diagram showing a display mode of the monitor at the III position, and FIG. 7B is an explanatory diagram showing a display mode of the monitor at the IV position. It is a block circuit diagram concerning an embedded state evaluation apparatus.

  The buried state evaluation method of the present invention will be described with reference to the accompanying drawings, taking as an example the case where the buried layer is a concrete layer 50 and the metal buried material is a metal pipe 60 such as a signal pillar, a sign pillar, or an illumination pillar. . In the following description, for the sake of convenience, there may be cases where the front / rear / left / right and up / down directions are defined, which indicates that the present invention is limited to the directions described in the following description. It is not a thing.

First, as shown in FIG. 1 (a), the metal tube 60 is not corroded and there is no gap between the metal tube 60 and the concrete layer 50. It is assumed that the transmitting unit 10 that transmits ultrasonic waves is disposed at the position of the height Y, and the receiving unit 20 that receives the ultrasonic waves is disposed at a position separated from the metal pipe 60 in the concrete layer 50 by the length X. Then, consider a case where an ultrasonic wave is transmitted from the transmitting unit 10 to the receiving unit 20 and the propagation time required for the ultrasonic wave to propagate the earliest is measured.
The healthy part actual measurement time Tm, which is the propagation time in the healthy part actually measured at this time,
Tm = Y / Cm + X / Cc
Can be expressed as Y: height of the metal tube 60 portion, X: length of the concrete layer 50 portion, Cm: sound velocity of the metal tube 60, Cc: sound velocity of the concrete layer 50.

In the above formula, by substituting the coefficient α where α = Cm / Cc,
Tm = Y / Cm + αX / Cm
It can be expressed as.

Furthermore, by applying Cm to the above formula,
Tm × Cm = Y + αX
It can be.

Here, Tm × Cm can be considered as a healthy part virtual propagation distance Wm _α that is a virtual propagation distance that travels when the ultrasonic wave propagates at the sound velocity of the metal tube 60 over the sound part actual measurement time Tm. ,
Wm _α = Y + αX
It can be expressed as.

If the coefficient β, which is β = Cc / Cm, is substituted for the coefficient α, the sound portion virtual propagation distance Wm _β that travels when the ultrasonic wave propagates at the sound speed of the concrete layer 50 over the sound portion actual measurement time Tm. Is
Wm _β = βY + X
Can also be expressed.

That is, as shown in FIG. 1B, the sound portion actual propagation time Wm _α (or Wm _β ) calculated from a known numerical value is used as the sound portion actual measurement time Tm of the ultrasonic wave displayed on the ultrasonic measuring instrument. Can correspond. That is, Tm as the propagation time which is the actual measurement time can be expressed by a virtual propagation distance Wm _α (or Wm _β ) calculated from known numerical values X, Y and α (or β).

Here, as shown in FIG. 2A, when the metal pipe 60 has a non-propagating portion 80 due to corrosion of the depth D or non-sticking of the depth D between the metal pipe 60 and the concrete layer 50, When the transmitting unit 10 and the receiving unit 20 are installed on a virtual coplanar surface including the non-propagating unit 80 and including the tube axis of the metal tube 60, ultrasonic waves propagate around the non-propagating unit 80. That is, the ultrasonic wave transmitted from the transmitter 10 travels further by a depth D after being lowered by the height Y on the outer surface of the metal tube 60, and from there, √ (X ² + D ² ) in the concrete layer 50.
Is received the earliest by following a route that propagates to the receiver 20 by a distance of.

Therefore, when an ultrasonic wave is transmitted from the transmitting unit 10 toward the receiving unit 20, the time Td required for the ultrasonic wave to propagate earliest is
Td = (Y + D) / Cm + (√ (X ² + D ² )) / Cc
Can be expressed as When this is expressed by the non-propagating portion depth direction virtual propagation distance Wd which is a virtual propagation distance as described above, from Wd = Td × Cm,
Wd _α = Y + D + α√ (X ² + D ² )
Or
Wd _β = β (Y + D) + √ (X ² + D ² )
It can be expressed as.

In this case as well, as shown in FIG. 2B, Td, which is the shortest propagation time of the ultrasonic wave displayed on the ultrasonic measuring instrument, is set as the non-propagating portion depth direction virtual propagation distance Wd _α ( Or Wd _β ).

And at this time, even if the depth D is unknown,
Tm: Wm _α = Td: Wd _α
Or Tm: Wm _β = Td: Wd _β
Since the relationship of
Wd _α = (Td / Tm) × Wm _α
Or Wd _β = (Td / Tm) × Wm _β
Thus, the non-propagating portion depth direction virtual propagation distance Wd _α (or Wd _β ) can be calculated, and the depth D is calculated from the calculated non-propagating portion depth direction virtual propagation distance Wd _α (or Wd _β ). Can be sought.

As shown in FIG. 3, when there is a non-propagating portion 80 due to corrosion of the width H or non-sticking of the width H between the metal tube 60 and the concrete layer 50, the width of the non-propagating portion 80. When the transmitting unit 10 and the receiving unit 20 are installed on a virtual same plane that includes a direction intermediate point and includes the tube axis of the metal tube 60, the ultrasonic wave propagates bypassing the non-propagating unit 80. That is, the ultrasonic wave transmitted from the transmitting unit 10 is √ (Y ² + (H / 2) ² ) on the outer surface of the metal tube 60.
After progression, √ (X ² + (H / 2) ² )
It can be considered that the signal is received earliest by following a route that propagates to the receiving unit 20.

Accordingly, when an ultrasonic wave is transmitted from the transmitting unit 10 toward the receiving unit 20, Th as a time required for the ultrasonic wave to propagate earliest is:
Th = (√ (Y ² + (H / 2) ² )) / Cm + (√ (X ² + (H / 2) ² )) / Cc
Can be expressed as When this is expressed by the non-propagating portion width direction virtual propagation distance Wh which is a virtual propagation distance as described above,
Wh _α = √ (Y ² + (H / 2) ² ) + α√ (X ² + (H / 2) ² )
Or Wh _β = β√ (Y ² + (H / 2) ² ) + √ (X ² + (H / 2) ² )
It can be expressed as.

In this case as well, as shown in FIG. 4, the shortest propagation time Th of the ultrasonic wave displayed on the ultrasonic measuring device corresponds to the non-propagating portion width direction virtual propagation distance Wh _α (or Wh _β ). Can be made.

  In actual ultrasonic measurement, the ultrasonic wave that has propagated around the non-propagating portion 80 by bypassing the shorter one of the depth direction and the width direction is received earliest.

  Therefore, when a propagation time longer than the healthy part actual measurement time Tm is measured, it can be determined whether it corresponds to Td or Th by applying the above equation. Regarding the width H of the non-propagating portion 80, the width measured for a measurement time that is longer than Tm by setting a plurality of measurement points and repeating the measurement is considered as the width H of the non-propagating portion 80 as it is. Can do.

  For example, as shown in FIG. 5, in the non-propagating portion 80 where the depth D is larger than the width H, the non-propagating portion width direction virtual propagation distance Wh is greater in the non-propagating portion depth direction virtual propagation. It becomes shorter than the distance Wd. Therefore, the shortest propagation time of the ultrasonic wave obtained as a result of measurement at the intermediate position II in the width direction H of the non-propagating portion 80 as shown in FIG. 6A is as shown in FIG. It can be considered that the non-propagating portion width direction virtual propagation distance Wh has been detected in consideration of the shortest healthy portion actual measurement time Tm of the ultrasonic wave obtained as a result of measurement at the healthy portion position I. At this time, the ultrasonic wave received after detouring in the depth D direction is displayed with a delay with respect to the ultrasonic wave received detouring in the width H direction. It becomes difficult to specify.

  For example, as shown in FIG. 7, in the non-propagating portion 80 having a width H greater than the depth D, the non-propagating portion depth direction virtual propagation distance Wd is greater in the non-propagating portion width direction. It becomes shorter than the virtual propagation distance Wh. Therefore, the shortest propagation time of the ultrasonic wave obtained as a result of measurement at the intermediate position IV in the width direction H of the non-propagating portion 80 as shown in FIG. 8A is as shown in FIG. It can be considered that the virtual propagation distance Wd in the non-propagation part depth direction is detected when the shortest propagation time Tm of the ultrasonic wave obtained as a result of the measurement by the sound part III is taken into consideration. At this time, the ultrasonic wave received after detouring in the width direction H is displayed with a delay with respect to the ultrasonic wave received detouring in the depth D direction. It becomes difficult to specify.

From the above, first, the healthy part actual measurement time Tm is actually measured by ultrasonic measurement of the healthy part, and the healthy part virtual propagation distance Wm _α (or calculated from this and the known numerical values X, Y, and α (or β). Wm _β ) and the time taken when the ultrasonic wave propagates from the transmitting unit 10 toward the receiving unit 20 with the shortest propagation distance in the evaluation target unit that is a portion for which it is desired to evaluate the suitability of the embedded state. Measure Tf (evaluation target actual measurement time)
Wf _α = (Tf _α / Tm) × Wm _α
Or Wf _β = (Tf _β / Tm) × Wm _β
The evaluation target part virtual propagation distance Wf _α (or Wf _β ) is specified, and the non-propagation part width direction virtual propagation distance Wh _α (or Wh _β ) calculated from the result of specifying the width H of the non-propagation part 80 is determined. Compared to
Wf _α = Wh _α
Or Wf _β = Wh _β
If so, since the depth D is larger than the width H of the non-propagating portion 80, it can be determined that the ultrasonic wave that has propagated around the non-propagating portion 80 in the width direction has been received first. .

Also,
Wf _α <Wh _α
Or Wf _β <Wh _β
If,
Wf _α = Y + D + α√ (X ² + D ² )
Or
Wf _β = β (Y + D) + √ (X ² + D ² )
Thus, the depth D of the non-propagating portion 80 can be calculated and specifically identified.

  Hereinafter, embodiments embodying the present invention will be described in detail. In addition, this invention is not limited to the Example shown below, A design change is possible suitably. By the way, when explaining the embodiments, there are cases where the front, rear, left and right and up and down directions are defined for convenience, but this is used only when the present invention is limited to the directions defined in the following embodiments. It is not something. The unit of time used in this embodiment is (second), the unit of length is millimeter (mm), and the unit of sound speed is (second / mm).

  For example, the corrosion state and the non-attached state at the road surface boundary portion between the metal pipe 60 (metal embedded material) formed of a cylindrical body and the concrete layer 50 (embedded layer) can be evaluated by the following procedure. In the present embodiment, an evaluation method using the coefficient α will be described.

  First, the transmitting unit 10 for transmitting the ultrasonic waves and the receiving unit 20 for receiving the ultrasonic waves of the embedded state evaluation apparatus 1 equipped with the ultrasonic measurement function set to the transmission method are both predetermined as healthy portions of the metal tube 60. (For example, 100 mm in the direction along the tube axis of the metal tube), and the ultrasonic wave propagation velocity (sound velocity of the metal tube 60) Cm on the surface of the metal tube 60 is calculated from the measurement time. At this time, the measurement time is specified based on the ultrasonic wave that has propagated earliest.

  Similarly, both the transmitting unit 10 and the receiving unit 20 are arranged at a predetermined distance (for example, 100 mm) from the concrete layer 50, and the ultrasonic wave propagation speed (concrete layer 50) on the surface of the concrete layer 50 is measured from the measurement time. Of sound) Cc. At this time, the measurement time is specified based on the ultrasonic wave that has propagated earliest.

  Next, in the healthy part of the metal pipe 60, the transmitting part 10 is arranged at a position where the height from the concrete layer 50 is Y, and the distance from the metal pipe 60 is located at a position where the distance from the metal pipe 60 is X in the concrete layer 50. A receiving unit 20 is arranged. At this time, the healthy part, the transmitting part 10, and the receiving part 20 are arranged on a virtual same plane including the pipe axis of the metal pipe 60. Thereby, X and Y can be set with accurate values. It should be noted that the height Y and the distance X are preferably 100 mm or less so that the attenuation of the ultrasonic wave does not matter and the error is small and accurate evaluation is performed.

  In this state, the healthy part actual measurement time Tm, which is the time taken when the ultrasonic wave propagates from the transmitting unit 10 toward the receiving unit 20 with the shortest propagation distance, is measured.

Wm = Y + αX
From this, the healthy part virtual propagation distance Wm is calculated.

  And in the evaluation object part of the metal pipe 60 which is a part which wants to evaluate an embedding state, the said transmission part 10 is arrange | positioned in the position whose height from the concrete layer 50 is Y, and in the concrete layer 50, it is from the metal pipe 60. The receiving unit 20 is arranged at a position where the distance is X. At this time, the evaluation target unit, the transmitting unit 10, and the receiving unit 20 are arranged on the same virtual plane including the tube axis of the metal tube 60. Note that the height Y and the distance X used at this time are set to be equal to the height Y of the transmitting unit 10 and the distance X of the receiving unit 20 arranged in the sound part.

  In this state, an evaluation target actual measurement time Tf, which is a time taken when an ultrasonic wave propagates from the transmitting unit 10 toward the receiving unit 20 with the shortest propagation distance, is measured.

After measuring the evaluation target part actual measurement time Tf,
Wf = (Tf / Tm) × Wm
Thus, the evaluation target part virtual propagation distance Wf is calculated.

A difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm is calculated. And
Wf-Wm <5
In the case of, it is evaluated that there is no corrosion. The reason for evaluating after calculating such a difference is that some errors are assumed during the measurement.

  Further, when calculating with Y = X = 100 mm and α = 1.5, if Wf−Wm is less than 5, the depth D is less than 5 mm and the width H exceeds 40 mm, or the depth D is 5 mm or more. And the non-propagating part 80 whose width H is 40 mm or less exists, and it is not assumed that it is a big corrosion or non-adhesion. For this reason, there is no problem even if it is evaluated that there is no corrosion or non-sticking and the measurement is finished. As a matter of course, the evaluation target part need not be limited to only one place, and a suspicious part or a predetermined measurement position may be used as the evaluation target part. Further, for example, in the cylindrical metal tube 60, four evaluation target portions are set every 90 degrees, and when the perimeter exceeds 800 mm, the evaluation target portions are appropriately set so that the interval between the evaluation target portions is 200 mm or less. A rule such as addition may be established.

Also,
Wf-Wm ≧ 5
If it is, it is evaluated that there is corrosion. In this case, move the evaluation target part in the left-right direction,
Wf-Wm = 0
The width H of the non-propagating part 80 is specified by obtaining the moving distance to be, and the intermediate position (H / 2 position) is specified in the width direction of the non-propagating part 80, and then the intermediate position is measured as the evaluation target part. A non-propagating portion width direction virtual propagation distance Wf is obtained. And evaluation object part virtual propagation distance Wf,
Wh = √ (Y ² + (H / 2) ² ) + α√ (X ² + (H / 2) ² )
Compared with the non-propagating part width direction virtual propagation distance Wh calculated from
Wf <Wh
In the case of Wf = Wd
age,
Wd = Y + D + α√ (X ² + D ² )
From this, the depth D of the non-propagating part 80 is calculated and specified.

  In addition, it is desirable that the measurement range of the evaluation target part virtual propagation distance Wf not exceed 2 × (X + Y). If Wf exceeds 2 × (X + Y), it is estimated that there is a problem with the transmission and reception of ultrasonic waves or that there is a non-propagating part 80 over a wide range. It can be evaluated that non-delivery is widespread.

Details of the tests evaluated using the embedded state evaluation method of this example will be described below.
Table 1 shows the results of evaluating the presence or absence of corrosion or non-sticking of the metal buried material embedded in the buried layer described below using the above-described buried state evaluation method. In addition, the transmission part 10 is arrange | positioned in the position of height Y = 70mm of metal embedding materials, and the receiving part 20 is arrange | positioned in the position of distance X = 70mm of a to-be-embedded layer.

Test 1
Metal burying material: road sign post (surface galvanized), outer diameter 165.2mm
Embedded layer: Concrete, gold finish on the surface Note: No corrosion or non-stick

Test 2
Metal buried material: Sign post (surface painting), outer diameter 318.5mm
Embedded layer: Concrete, Surface paint finish Remarks: No corrosion or non-stick

Test 3
Metal burying material: 6mm steel plate (base), width 250mm
Embedded layer: Concrete, surface gold finish Note: A non-propagating part with a depth of 20 mm and a width of 250 mm (full width) is formed.

Test 4
Metal buried material: Steel pipe (base), outer diameter 165.2mm
Embedded layer: Concrete, gold finish on the surface Note: No corrosion or non-stick

Test 5
Metal buried material: Steel pipe (base), outer diameter 165.2mm
Embedded layer: Concrete, surface gold finish Note: A non-propagating part with a depth of 30 mm and a width of 40 mm is formed.
Depth length of the non-propagating part along the direction from the central axis of the steel pipe toward the center of the non-propagating part is 2 mm.

Test 6
Metal buried material: Steel pipe (base), outer diameter 165.2mm
Embedded layer: Concrete, surface gold finish Note: A non-propagating part with a depth of 30 mm and a width of 62 mm is formed.
Depth length of the non-propagating part 6mm along the direction from the central axis of the steel pipe toward the center of the non-propagating part

Test 7
Metal buried material: Steel pipe (base), outer diameter 165.2mm
Embedded layer: Concrete, surface gold finish Note: A non-propagating part with a depth of 25 mm and a width of 94 mm is formed.
Depth length of the non-propagating part along the direction from the central axis of the steel pipe toward the center of the non-propagating part is 15 mm.

  In Test 1, Test 2 and Test 4 with no corrosion or non-sticking, Wf-Wm is all 0 or 1 less than 5, indicating that there is no corrosion or non-sticking properly.

  Moreover, also in Test 3, Test 5, Test 6, and Test 7 in which the non-propagating part is provided, a result that correctly reflects the actual size of the non-propagating part was obtained.

The embedded state evaluation apparatus 1 used in the above embodiment will be described with reference to FIG.
The embedded state evaluation device 1 includes a transmitting unit 10 that transmits ultrasonic waves and a receiving unit 20 that receives the ultrasonic waves. Further, in the sound part, the ultrasonic waves are directed from the transmitting unit 10 to the receiving unit 20. And a CPU (Central Processing Unit) having a control content for measuring the measurement time required for propagation at the shortest propagation distance.

  Specifically, the propagation time is calculated based on the waveform data transmitted from the transmitting unit 10 and the receiving unit 20 to the CPU, and the data is stored and held in the storage device RAM. Furthermore, the CPU stores and holds the sound portion actual measurement propagation time Tm, the evaluation target portion actual measurement time Tf, the sound velocity Cc of the buried layer, the sound velocity Cm of the metal embedded material, and the coefficient α calculated and stored. And the control contents for calculating the healthy part virtual propagation distance Wm and the evaluation target part virtual propagation distance Wf based on the height Y and the distance X input by the user. Further, it is extremely desirable that the embedded state evaluation apparatus 1 includes a monitor as the waveform display device 30 that displays the ultrasonic waves received by the receiving unit 20.

  In addition, the sound part virtual propagation distance specific | specification means concerning this invention and the evaluation object part virtual propagation distance specific | specification means are comprised by CPU which performs the said control content.

  Furthermore, the embedded state evaluation method of the present invention not only evaluates the corrosion state of the metal embedded material or the non-attached state between the embedded layer and the metal embedded material, but also embeds at the boundary portion between the embedded layer and the embedded material. The non-attached state between the material and the buried layer can also be evaluated. In other words, even if the burying material is not made of metal, the ultrasonic wave is not propagated in the portion where the burying material and the buried layer are not attached, or it is extremely attenuated and cannot be measured. It can be evaluated nondestructively whether or not there is a non-attached portion at the boundary portion between the buried material and the buried layer that should be in close contact with each other.

  Further, in order to make the embedded state evaluation method of the present invention as accurate as possible, it is desirable that the arrangement position of the transmitting unit 10 and the receiving unit 20 is a position free from rust and dirt. In severe cases, it is desirable to arrange the transmitter 10 or the receiver 20 on a smooth surface by polishing or the like. Note that the wavelength of the ultrasonic wave used in the present invention and the vibration direction of the wave can be freely selected as appropriate. For example, when the buried material is a steel pipe and the buried layer is a concrete layer, a so-called P wave or a so-called LA wave may be used. Also, a so-called SH wave or a so-called SN wave may be used. A desirable wavelength is 1 MHz or less, and a more desirable wavelength is 500 kHz or less. Moreover, as a burying material, a cross section may be round shape or square shape, and other shapes may be sufficient as it. Further, the buried material does not need to be a pipe material.

DESCRIPTION OF SYMBOLS 1 Embedded state evaluation apparatus 10 Transmission part 20 Reception part 30 Waveform display apparatus

Claims (6)

A transmitter for transmitting ultrasonic waves is disposed on one of the outer surface of the metal burying material partially embedded in the embedded layer and the surface of the embedded layer, and the ultrasonic wave is received on the other side. It is a buried state evaluation method in which a receiving unit is arranged to evaluate a corrosion state of a metal buried material or a non-attached state between a metal buried material and a buried layer at a boundary portion between the buried layer and the metal buried material. ,
Measuring the time taken when the ultrasonic wave propagates from the transmitter to the receiver at the shortest propagation distance in the healthy part; and
The measurement time is the healthy part actual measurement time Tm.
(Tm = Y / Cm + X / Cc Y: distance of metal burying material portion X: distance of buried layer portion Cm: sound velocity of metal burying material Cc: sound velocity of buried layer)
age,
It was calculated on the assumption that the ultrasonic wave propagated from the transmitting part to the receiving part at the sound part over the sound part actual measurement time Tm only at the sound velocity of either the metal burying material or the buried layer. Healthy part virtual propagation distance Wm which is a virtual propagation distance
(Wm = Y + αX α = Cm / Cc when the sound velocity of the metal burying material is used.
(Sound velocity of buried layer Wm = βY + X β = Cc / Cm)
A process of identifying
A step of measuring the time taken when an ultrasonic wave propagates from the transmitter to the receiver in the shortest propagation distance in the evaluation target part which is a part where the embedded state is to be evaluated;
The measurement time in the evaluation target part is set as the evaluation target part actual measurement time Tf, and the evaluation target part virtual time is based on the evaluation target part actual measurement time Tf, the healthy part actual measurement time Tm, and the healthy part virtual propagation distance Wm. Propagation distance Wf
(Wf = (Tf / Tm) × Wm)
A process of identifying
Evaluating the embedded state of the evaluation target part based on the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm;
The embedded state evaluation method characterized by having. When the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm exceeds a predetermined threshold, a plurality of the evaluation target parts are set, and the metal embedment material and the buried layer A step of specifying a width H along the circumferential direction of the metal buried material in the non-propagating part consisting of a corroded part or a non-attached part in the boundary part with
Furthermore, the evaluation target part virtual propagation distance Wf specified by setting the intermediate point of the width H on the shortest path between the transmission part and the reception part,
Wh = √ (Y ² + (H / 2) ² ) + α√ (X ² + (H / 2) ² )
Or Wh = β√ (Y ² + (H / 2) ² ) + √ (X ² + (H / 2) ² )
Non-propagating part width direction virtual propagation distance Wh calculated by:
And the step of evaluating the depth D of the non-propagating part. Wf = Wh
If so, the embedded state evaluation method according to claim 2 including a step of evaluating that the depth D of the non-propagating portion is larger than the width H. Wf <Wh
If,
Wf = Y + D + α√ (X ² + D ² )
Or Wf = β (Y + D) + √ (X ² + D ² )
The embedded state evaluation method according to claim 2, further comprising a step of identifying a depth D of the non-propagating portion. An embedded state evaluation device used in the embedded state evaluation method according to any one of claims 1 to 4,
A transmitter that transmits ultrasonic waves;
A receiving unit for receiving the ultrasonic wave;
In the sound part, the measurement time taken when the ultrasonic wave propagates from the transmitter part to the receiver part with the shortest propagation distance is the sound part actual measurement time Tm.
(Tm = Y / Cm + X / Cc Y: distance of metal burying material portion X: distance of buried layer portion Cm: sound velocity of metal burying material Cc: sound velocity of buried layer)
age,
It was calculated on the assumption that the ultrasonic wave propagated from the transmitting part to the receiving part at the sound part over the sound part actual measurement time Tm only at the sound velocity of either the metal burying material or the buried layer. Healthy part virtual propagation distance Wm which is a virtual propagation distance
(Wm = Y + αX α = Cc / Cm in the case of the sound velocity of the metal buried material
(Sound velocity of buried layer Wm = βY + X β = Cm / Cc)
Sound part virtual propagation distance specifying means for specifying
The measurement time taken when the ultrasonic wave propagates from the transmitting unit to the receiving unit with the shortest propagation distance in the evaluation target part that is the part for which the embedded state is to be evaluated is defined as the evaluation target part actual measurement time Tf, and the evaluation target part Based on the actual measurement time Tf, the healthy part actual measurement time Tm, and the healthy part virtual propagation distance Wm, the evaluation target part virtual propagation distance Wf
(Wf = (Tf / Tm) × Wm)
Evaluation target part virtual propagation distance specifying means for specifying,
An embedded state evaluation apparatus comprising: A transmitter for transmitting ultrasonic waves is arranged on either one of the outer surface of the buried material partially embedded in the buried layer and the surface of the buried layer, and a receiving unit for receiving the ultrasonic waves is arranged on the other side. An embedded state evaluation method for arranging and evaluating a non-attached state between the buried material and the buried layer at a boundary portion between the buried layer and the buried material,
Measuring the time taken when the ultrasonic wave propagates from the transmitter to the receiver at the shortest propagation distance in the healthy part; and
The measurement time is the healthy part actual measurement time Tm.
(Tm = Y / Cm + X / Cc Y: distance of the buried material portion X: distance of the buried layer portion Cm: sound velocity of the buried material Cc: sound velocity of the buried layer)
age,
The hypothetical wave calculated on the assumption that the ultrasonic wave propagated from the transmitting part to the receiving part over the sound part actual measurement time Tm at only one sound speed of the buried material and the buried layer in the healthy part. Healthy part virtual propagation distance Wm which is propagation distance
(Wm = Y + αX α = Cc / Cm when the sound velocity of the buried material is used.
(Sound velocity of buried layer Wm = βY + X β = Cm / Cc)
A process of identifying
Measuring the time taken when the ultrasonic wave propagates from the transmitting unit to the receiving unit with the shortest propagation distance in the evaluation target unit, which is a portion where the non-attachment state is to be evaluated, and
The measurement time in the evaluation target part is set as the evaluation target part actual measurement time Tf, and the evaluation target part virtual time is based on the evaluation target part actual measurement time Tf, the healthy part actual measurement time Tm, and the healthy part virtual propagation distance Wm. Propagation distance Wf
(Wf = (Tf / Tm) × Wm)
A process of identifying
Evaluating the embedded state of the evaluation target part based on the difference between the evaluation target part virtual propagation distance Wf and the healthy part virtual propagation distance Wm;
The embedded state evaluation method characterized by having.

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