JP2016024147A - Crack detection sensor and measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a new crack detection sensor embedded in a concrete structure in order to detect a crack in concrete.SOLUTION: With a crack detection sensor 2, a sufficiently thin conductive wire 5 that breaks simultaneously when crack occurs is embedded in a tabular body 3 formed by mortar and concrete used in a concrete structure. The conductive wire 5 is connected with a first terminal line 41 and a second terminal line 42 that are in parallel to one side of the tabular body 3 and disconnection check (continuity check) can be performed externally. The first and second terminal lines 41 and 42 are an electric wire having sufficient intensity so as not to be broken even when being hit by concrete to be installed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a crack detection sensor or the like embedded in a concrete structure in order to detect cracks inside the concrete.

  A concrete structure undergoes various deformations such as cracks and corrosion of reinforcing bars due to aging. In particular, cracks occurring inside the concrete cannot be visually confirmed, and are often found in a state where the deformation has progressed considerably and the proof stress has been lowered, and early detection is desired.

  As a technique for detecting cracks generated in concrete, for example, a method of burying a conductive wire inside a concrete structure and inspecting its conduction has been known. That is, this has been detected by breaking the conductive wire with the occurrence of a crack (see, for example, Patent Document 1).

JP-A-9-159638

  However, it is necessary to install a conductive wire by placing a conductive wire at the time of bar arrangement, and there is a problem that the conductive wire is easily disconnected at the time of placing the concrete.

  The present invention has been devised in view of the above-described problems, and its object is to realize a new crack detection sensor embedded in a concrete structure in order to detect cracks inside the concrete. is there.

  A first invention for solving the above problems is a crack detection sensor embedded in a concrete structure in order to detect cracks in the concrete, and is a plane formed using concrete or mortar as a hardener. A plate-like body having a polygonal view, a first terminal line and a second terminal line provided so as to be drawn from one side of the plate-like body, and the plate connecting the first terminal line and the second terminal line And a conductive wire embedded in the body.

  According to the first aspect of the invention, there are different types of conductive wires that are essential for detecting cracks, and the first terminal wires and the second terminal wires for checking the continuity / non-conduction from the outside, that is, the disconnection check and the continuity check. As a whole line, a plate-like body having a polygonal shape in plan view can be obtained. That is, while the conductive wire is a thin wire that is broken to the extent that the plate-like body is cracked, the first terminal wire and the second terminal wire are made thick lines that are not broken by the force of placing concrete, and the plate-like body is made of concrete. Alternatively, it can be formed using mortar as a curing agent. Therefore, the disconnection defect at the time of construction can be reduced. Further, since the first terminal line and the second terminal line are drawn out from the same side of the plate-like body, it is easy to wire the two lines together and the workability is improved. Moreover, the workability at the time of crack inspection after being buried is improved.

  The second invention is the crack detection sensor according to the first invention, wherein the conductive wires meander and are wired in the plate-like body.

  According to the second aspect of the present invention, the conductive wires are evenly distributed throughout the plate-like body, and it is possible to reliably detect where a crack occurs in the plate-like body.

Note that the number of combinations of the conductive wires, the first terminal wires, and the second terminal wires provided in one crack detection sensor is not limited to one, and a plurality of combinations may be provided.
For example, as a third invention, a plurality of the first terminal lines spaced on one side of the one side and the same number of the second terminal lines as the first terminal lines spaced on the other side of the one side The crack detection sensor according to the first or second invention is configured in which a plurality of the conductive wires are embedded in an annual ring shape so as to connect the corresponding first terminal wires and the second terminal wires. can do.

  According to a fourth aspect of the present invention, N conductive wires are provided such that the conductive wires are meandered in the plate-like body, connected to the meandering wires of the conductive wires, and drawn from the one side (N ≧ 1). The crack detection sensor according to the first aspect of the present invention further provided with a terminal wire.

According to the fourth invention, since one conductor wire is divided into a plurality of portions (in other words, the conductor wires are connected in series and can be checked for disconnection), even without using a plurality of crack detection sensors, From the time when the disconnection is detected and the positional relationship between the divided portions, it is possible to estimate the position where the crack is generated, the traveling direction, and the degree of progress.
In addition, it is possible to provide a backup by preparing a plurality of terminal wires and to compensate the detection function even if the terminal wires are disconnected due to the concrete placement.

  5th invention is the measuring method by the measuring apparatus connected to the crack detection sensor of 3rd invention, Comprising: The step which confirms conduction | electrical_connection between the said 1st terminal wire and said 2nd terminal wire corresponding, Determining the progress of cracks based on the confirmation result.

  According to the fifth aspect, even with a single crack detection sensor, it is possible to estimate the direction and degree of progress of the crack.

  6th invention is a measuring method by the measuring apparatus connected to the crack detection sensor of 4th invention, Comprising: Any of said 1st terminal wire, said 2nd terminal wire, and said N terminal wires And a step of determining a crack occurrence position based on the result of the confirmation.

  According to the sixth aspect of the invention, it is possible to estimate the occurrence position of a crack even with one crack detection sensor.

The figure for demonstrating the structural example and creation procedure of a crack detection sensor. The figure which shows the example of installation of a crack detection sensor. The flowchart for explaining the flow from construction of a concrete structure to installation of crack detection sensors and crack detection measurement. The figure which shows the modification of a crack detection sensor. The figure which shows the modification of a crack detection sensor. The figure which shows the modification of a crack detection sensor. The figure which shows the modification of a crack detection sensor. The figure which shows the modification of a crack detection sensor. The figure which shows the modification of a crack detection sensor.

FIG. 1 is a diagram for explaining a configuration example and a creation procedure of a crack detection sensor.
The crack detection sensor 2
1) Plane-view polygonal plate-like body 3 formed using concrete or mortar as a hardener,
2) a first terminal line 41 and a second terminal line 42 provided so as to be drawn from one side of the plate-like body 3;
3) The conductive wire 5 embedded in the plate-like body 3 connecting the first terminal wire 41 and the second terminal wire 42.

  The plate-like body 3 has a rectangular shape in plan view in the illustrated example, but may have another polygonal shape (for example, a triangle). The thickness can be appropriately set to such an extent that cracking does not occur due to impact during transportation. It is preferable that the hardened material is concrete having the same or similar composition as that used for placing a concrete structure to be detected for cracking, or mortar using the same cement.

  The first terminal wire 41 and the second terminal wire 42 are electric wires that are more resistant to disconnection than the conductive wire 5. Specifically, it is assumed that the concrete structure has a strength that does not break against an external force generated by the concrete flowing down during placement when the concrete structure is constructed. A bare wire or a covered wire may be used. In the illustrated example, the wires are independent from each other, but a twisted wire, a twisted pair wire, and a coaxial wire by a plurality of wires may be used as appropriate.

  The conductive wire 5 is a thin conductive wire such as metal or carbon fiber, and is a bare electric wire. If the plate-like body 3 is cracked, it is weak enough to break. For example, in the case of enamel wire, it is about 0.01 to 0.05 mm. And it is wired so that it may cross | intersect with the direction of the crack line CL (in other words, crack to be detected).

The procedure for creating the crack detection sensor 2 is as follows.
Procedure 1) Put the curing material 7 about half the depth of the mold 6.
Procedure 2) If the hardening material 7 is properly solidified, the first terminal wire 41, the second terminal wire 42, and the conductive wire 5 that are connected in advance are placed in the mold 6, and the remaining hardening material 7 is attached. Put in.
Procedure 3) The mold 6 is removed after curing.

FIG. 2 is a diagram illustrating an installation example of the crack detection sensor 2.
FIG. 3 is a flowchart for explaining the flow from the construction of the concrete structure to the installation of the crack detection sensor and the crack detection measurement.

First, the crack detection sensor 2 is created in advance (step S2).
And the created crack detection sensor 2 is embedded in the predetermined position of the concrete structure 8 used as the detection object of a crack by single or plural (three in the example of FIG. 2) with a predetermined attitude. Specifically, after the reinforcement of the concrete structure 8 and the installation of the formwork are completed (step S4), the creation of the crack detection sensor 2 within the range of the assumed crack line CL ′ (see FIG. 2) of the concrete structure 8 The crack detection sensor 2 is arranged so that the crack line CL that is sometimes assumed follows the assumed crack line CL ′ (step S6). At this time, the first terminal line 41 and the second terminal line 42 are appropriately arranged to be arranged outside the formwork of the concrete structure 8. Then, concrete is placed (step S8).

  When the concrete is hardened, the formwork is removed (step S10), and the use of the concrete structure 8 is started (step S12). Then, the first terminal line 41 and the second terminal line 42 are connected to the measuring device 9 to start a continuous or periodic disconnection check (continuity check) (step S14).

As a result of the measurement, it is possible to determine where the crack has occurred inside the concrete structure 8 from the embedment position of the crack detection sensor 2 that is first detected to be disconnected (step S16).
Furthermore, by tracing the embedded positions of the plurality of crack detection sensors 2 in the order in which the disconnection is detected one after another, it is possible to determine the internal crack occurrence position and the subsequent traveling direction, its speed, that is, the progress of the crack. Yes (step S18).

  As described above, according to the present embodiment, even if the conductive wire 5 that is the liver of detection is sufficiently thin and weak so that it can be detected even with a weak crack, since it is embedded in the plate-like body 3 in advance, Even if an external force is applied during installation or when placing concrete, it is not easily cut.

  Further, the first terminal line 41 and the second terminal line 42 are provided so as to be drawn from one side of the plate-like body 3. Of the first terminal wire 41 and the second terminal wire 42, it is possible to twist the portions until they are drawn out of the concrete structure 8. That is, handling of the terminal wire is facilitated, and even when the concrete flowing down at the time of placement hits, it can be prevented from being easily disconnected. The workability can be further improved compared to the conventional case.

  The embodiment of the crack detection sensor of the present invention is not limited to the above, and components can be added, omitted, or changed as appropriate.

  For example, in the example of FIG. 1, the conductive wire 5 is folded once, but as shown in the crack detection sensor 2 </ b> B of FIG. 4, the conductive wire 5 is meandering and wired to the plate-like body 3. It is good as well. This configuration is suitable when the region where cracks are expected to occur is wide, or when the generation location and direction of the assumed crack line CL cannot be narrowed down.

Further, like the crack detection sensor 2C of FIG. 5, the same side as the first terminal line 41 and the second terminal line 42 is connected to the middle of the conductive wire 5 meandering in the plate-like body 3 and wired. N terminal lines (N ≧ 1) provided so as to be led out from the terminal (in the illustrated example, the third terminal line 43 and the fourth terminal line 44: N = 2) may be provided.
According to this configuration, by changing the combination of the terminal wires used for the disconnection check, it is possible to check each part of the meandering conductive wire 5 and more specifically determine the crack position.
In addition, the terminal wire is set to a thickness that sufficiently resists the external force at the time of placing concrete, but it cannot be determined unless it is disconnected. However, if three or more terminal wires are prepared as in the configuration, if there are two healthy terminal wires, the function of detecting cracks using the portion of the conductive wire 5 to which the two terminal wires are connected is used. Can be compensated.

  Further, as in the case of the crack detection sensors 2D, 2E, 2F, and 2G in FIGS. 6 to 9, it is possible to provide a plurality of sets in which the first terminal wire 41, the second terminal wire 42, and the conductive wire 5 are set as one set. is there. In this case, by performing a disconnection check for each set in step S16 and step S18, even with one crack detection sensor, it is possible to estimate the occurrence position of the crack, the direction of progress of the crack, and the progress of the crack. .

  In particular, like the crack detection sensor 2E of FIG. 7, a plurality of first terminal lines 41, 41,... Are provided on one side of one side of the plate-like body 3, and the other side of the one side is spaced. Are provided with the same number of second terminal lines 42, 42,... As the first terminal lines, and the plurality of conductive lines 5, 5,. If it embed | buries and comprises in the plate-shaped body 3 like an annual ring so that 42 may be connected, it is effective in the detection of the following cracks. That is, it is effective for detecting the cracks when the occurrence and progress of cracks are assumed from the center part of the annual rings of the conductive wires 5, 5,. For example, in a concrete structure, when the crack occurrence position in the concrete can be estimated approximately, if the crack detection sensor 2E is embedded so that the center part of the annual ring is located in the vicinity of the crack occurrence position, the crack progress ( It is possible to measure the direction of crack propagation and the rate of progress.

2, 2B, 2C, 2D, 2E, 2F, 2G ... Crack detection sensor 3 ... Plate-like body 5 ... Conductive wire 6 ... Formwork 7 ... Hardening material 8 ... Concrete structure 9 ... Measuring device 41 ... First terminal wire 42 ... 2nd terminal wire 43 ... 3rd terminal wire 44 ... 4th terminal wire

Claims (6)

A crack detection sensor embedded in a concrete structure to detect cracks in the concrete,
A plate-like body having a polygonal shape in plan view formed using concrete or mortar as a hardener;
A first terminal line and a second terminal line provided so as to be drawn from one side of the plate-like body;
A conductive wire embedded in the plate-like body connecting the first terminal wire and the second terminal wire;
Crack detection sensor with The crack detection sensor according to claim 1, wherein the conductive wire is meandered and wired in the plate-like body. A plurality of the first terminal lines are provided at intervals on one side of the one side, and the same number of the second terminal lines as the first terminal lines are provided at intervals on the other side of the one side,
A plurality of the conductive wires are embedded in an annual ring shape so as to connect the corresponding first terminal wires and the second terminal wires,
The crack detection sensor according to claim 1 or 2. The conductive wire is meandered and wired in the plate-like body,
The crack detection sensor according to claim 1, further comprising N terminal lines (N ≧ 1) provided so as to be connected in the middle of the meandering wiring of the conductive lines and drawn from the one side. A measurement method by a measurement device connected to the crack detection sensor according to claim 3,
Confirming conduction between the corresponding first terminal lines and the second terminal lines;
Determining the development of cracks based on the confirmation results;
Measuring method including A measurement method using a measurement device connected to the crack detection sensor according to claim 4,
Confirming conduction in any combination of the first terminal line, the second terminal line, and the N terminal lines;
Determining a crack occurrence position based on the confirmation result;
Measuring method including

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