JP6489527B2 - Method and apparatus for measuring current strain of concrete structures - Google Patents

Description

  The present invention relates to an existing strain measuring method and measuring apparatus used when evaluating the mechanical performance of a concrete structure, and more particularly to an existing strain measuring method and measuring apparatus using a stress release method.

  One of the methods for measuring the existing strain of a concrete structure is a stress release method. The stress release method is characterized in that the existing strain (or the existing stress) can be measured with high accuracy by microfracture, and conventionally, a plurality of measurement methods or measurement apparatuses applying the stress release method have been proposed.

  The measuring method disclosed in Patent Document 1 is characterized in that the existing stress inside the structural member is measured using a strain gauge attached to the surface of the structural member. First, a strain gauge is attached to the surface of the structural member, and an initial value (a value in a stress unreleased state) is measured. After that, a circular groove is drilled with the outer periphery of the strain gauge facing from the surface to the center. When the center surface of the cylindrical body inside the circular groove is first in a stress-free state, the final value (stress released state) Value), and the difference between the final value and the initial value is calculated to estimate the existing stress.

  In the measurement method disclosed in Patent Document 2, as in the measurement method of Patent Document 1, the existing stress inside the concrete structure is measured using a strain gauge attached to the surface of the concrete structure. However, in the case of this measuring method, a plurality of strain gauges are arranged in an annular shape on the surface of the concrete structure, and a circular groove is drilled with the inner side of the annular shape as the center. The idea is that the existing stress is estimated by analyzing the difference between the initial value measured before drilling and the final value measured after drilling.

  The measurement method disclosed in Non-Patent Document 1 is a measurement method by the inventors of the present application, characterized in that the existing strain of a concrete structure is measured using a strain gauge embedded in the concrete structure. is there. Hereinafter, the measurement method of Non-Patent Document 1 will be described in detail with reference to FIGS. Here, the concrete structure 10 to be measured is an RC structure in which a plurality of reinforcing bars 14 are embedded in a prismatic concrete material 12, as shown in FIG.

  As shown in FIG. 3A, the strain gauge 16 includes a sensor body 18 and a cable 20. The sensor main body 18 is the same as the embedded sensor described in FIG. 10 of Non-Patent Document 1, and two small columnar strain sensors are integrally fixed via a substantially rectangular parallelepiped mortar. The cable 20 is a signal line for outputting a strain signal detected by the strain sensor to the outside, and a cable 20 a on the sensor body 18 side and a cable 20 b on the output end side are connected via a connector 22.

  As preparation for measurement, a deep hole-like embedded space 12b is formed by digging deeply inward from the surface 12a (1) of the concrete structure 12. Thereafter, the sensor body 18 is disposed in the embedded space 12b, the cable 20b and the connector 22 are pulled out of the surface 12a (1) through the embedded space 12b, and in this state, the embedded space 12b is filled with a filler 24 such as mortar. Then, the sensor body 18 is fixed to the measurement point in the concrete structure 10. Then, an analysis device 26 for distortion signal analysis constituted by a data logger, a personal computer or the like is connected to the output end of the cable 20. Now, as shown in FIG.3 (b), it will be in the state which can start a measurement.

  In the measurement, first, a strain signal is acquired using the analysis device 26 in the state of FIG. 3B, and then the connector 22 is removed and the strain gauge 16 and the analysis device 26 are disconnected. Next, as shown in FIG. 3C, the outer core 30 having a circular groove shape is cut using the main core drill 28 inward from the outer peripheral portion of the opening end of the embedded space 12b on the surface 12a (1). Make a hole. Then, the hole is stopped when the depth of the outer core 30 exceeds the position of the sensor body 18, and the main core drill 28 is retracted to the outside of the concrete structure 10. As a result, the measurement point to which the sensor body 18 is fixed enters the stress release state. Thereafter, as shown in FIG. 3D, the connector 22 is connected, and the analysis device 26 is connected to the strain gauge 16 to acquire a strain signal. Then, the analysis device 26 analyzes the strain signal acquired before drilling the outer core 30 and the strain signal acquired after drilling to calculate the existing strain.

JP 2006-146347 A JP 2010-60490 A

Wakkai, Hajime Ito, Satoshi Nishino, Yuri Takatsuki Experimental research on measurement of released strain of expansive concrete using embedded sensor, Concrete Engineering Annual Papers, Vol. 35, no. 1, 2013, p. 367-372

  In the case of the measurement method using the stress release method, in order to further improve the measurement accuracy, it is important to accurately detect the strain before the stress release at the measurement point and the strain after the stress release. The problem is how to accurately detect the later distortion. Therefore, in the measurement method of Non-Patent Document 1, the behavior of the strain signal that changes in the process of drilling the outer core 30 to appropriately determine whether or not the internal stress at the measurement point has been sufficiently released. And determining whether or not the drilling depth has reached a sufficient depth (see FIG. 11 of Non-Patent Document 1).

  However, when the measuring device of Non-Patent Document 1 is used, due to the structural limitations of the strain gauge 16, the analysis device 26, and the main drill core 28, drilling of the outer core 30 and acquisition of strain signals are performed in parallel. I can't. That is, in order to observe the behavior of the strain signal that changes in the process of drilling the outer core 30, the drilling is interrupted every time the outer core 30 becomes slightly deeper, the main core drill 28 is temporarily retracted, and the cables 20a, 20b. Are connected (the analysis device 26 is connected to the strain gauge 16), the strain signal is acquired, and then the cables 20a and 20b are disconnected and the next drilling is resumed. Accordingly, the work efficiency is very poor, and the drilling work becomes discontinuous, and an error is likely to occur in the value of the distortion signal. Further, when cutting water is supplied to the cutting edge of the main core drill 28 during drilling, the cutting water is applied to the connector 22 and the cable 20a. For example, the connector 22 is covered with a waterproof cover or the like during drilling, and the analysis device 26 Since a waterproof measure is required to remove the prevention cover each time the is connected, the work becomes very complicated. This is a problem that also occurs in the measurement method of Patent Document 1.

  The above-described problem can be solved by using a special main core drill 32 as shown in FIGS. 4A, 4B, and 4C, for example. Since the main core drill 32 is provided with a through hole 32a at the position of the rotation shaft, the cable 20 of the strain gauge 16 (the connector 22 is not used) can be passed through the through hole 32a and connected to the analysis device 26. Even if the drilling operation is not interrupted, strain signals can be continuously acquired, and the above-described waterproofing measures are not required. However, it is not easy to obtain a special core drill such as the main core drill 32, and there is a problem that the cost burden increases even if it is newly manufactured.

  On the other hand, since the measurement method of Patent Document 2 can acquire a strain signal while continuing drilling, the above-described problem does not occur. However, since the strain gauge is arranged outside the circular groove in a state where the circular groove is drilled, the strain gauge detects a strain at a position where the stress is not completely released even after drilling. Therefore, the final value measured after drilling is only an indirectly measured value of the stress release state. Therefore, even if complicated calculation is performed to correct indirect elements, it is difficult to accurately estimate the existing distortion.

  The present invention has been made in view of the above-mentioned background art, and is capable of efficiently acquiring a strain signal in the process of drilling an outer core, and can measure the existing strain with higher accuracy. And it aims at providing a measuring device.

  The present invention provides an embedding space forming step for forming a pothole-shaped embedding space inward from a first surface of a concrete structure, and the embedding space from a second surface at a position away from the first surface. A strain gauge comprising a guide hole forming step for forming a guide hole communicating with the inside of the sensor, a sensor body having a strain sensor, and a cable for externally outputting a strain signal detected by the strain sensor, A main body is disposed in the embedded space, and the cable is pulled out of the second surface through the guide hole, and in this state, the embedded material is filled with a filler to form the sensor main body in the concrete structure. A strain gauge installation step for fixing to an object, and a circular groove shape using a main core drill inward from the outer peripheral portion of the opening end of the embedded space on the first surface. An outer core drilling step for drilling the outer core and an analysis device for strain signal analysis are prepared, and the analysis device is connected to the output end of the cable so that the strain signal can be received. And measuring the existing strain of the concrete structure by analyzing the behavior of the strain signal that changes during the outer core drilling step and calculating the existing strain of the concrete structure. Is the method.

Alternatively, as another method , an embedding space forming step for forming a pothole-shaped embedding space inward from the first surface of the concrete structure, a sensor body having a strain sensor, and a strain signal detected by the strain sensor A strain gauge composed of a radio device for external output is prepared, the sensor main body is arranged in the embedded space, and in this state, the embedded space is filled with a filler, and the strain gauge is used as the concrete structure. A strain gauge installation step for fixing to an object, and an outer core cutting for drilling a circular outer core using a main core drill inward from the outer peripheral portion of the opening end of the embedded space on the first surface. A hole process and a device for analyzing a distortion signal, and preparing an analysis device having a communication function capable of receiving a distortion signal output from the wireless device, using the analysis device, Analyzing the behavior of the distortion signal which changes in the course of the Utakoa drilling process, it is also possible to calculate the existing strain of the concrete structure.

  In the embedded space forming step, inward from the first surface, a circular inner core is drilled using an auxiliary core drill, and the concrete material inside the inner core is removed to form the embedded space It is preferable to adopt a configuration of.

  The present invention also provides an auxiliary drilling tool for digging inwardly the first surface of a concrete structure to form a pothole-shaped embedded space, and a second at a position away from the first surface. A drill hole for forming a guide hole leading from the surface of the embedded space to the inside of the embedded space, and a circular groove-shaped outer core inward from the outer peripheral portion of the opening end of the embedded space of the first surface. It has a main core drill for drilling, a strain sensor, a sensor body fixed in the embedded space together with the strain sensor, and a cable for outputting strain signals detected by the strain sensor to the outside. A strain gauge and an analysis device for analyzing the strain signal, wherein the cable is drawn out of the second surface through the guide hole, and the analysis device outputs the strain signal through the cable. And Shin, by analyzing the behavior of the distortion signal which changes in the course of drilling the outer core, which is existing distortion measuring apparatus of the concrete structure to calculate the existing strain of the concrete structure.

Alternatively, as another device , a strain meter including a strain sensor, a sensor main body fixed together with the strain sensor in the embedded space, and a wireless device for externally outputting a strain signal detected by the strain sensor Can also be used .

  The auxiliary drilling tool is an auxiliary core drill for drilling a circular groove-shaped inner core inward from the first surface of the concrete structure, and the embedded space is formed by a concrete material in the inner core. It is preferable that the space is a space after removal.

  Since the present strain measurement method for a concrete structure according to the present invention can continuously perform drilling of the outer core and acquisition of a strain signal in parallel, the working efficiency is very good. In addition, since the behavior of the strain signal that changes in the process of drilling the outer core can be observed with higher accuracy, it is possible to properly determine whether the internal stress at the measurement point has been sufficiently released. Thus, it is possible to accurately detect the strain after releasing the stress at the measurement point. Then, by performing a predetermined calculation process using the detected strain signals before and after stress release, the existing strain can be calculated with high accuracy.

  In addition, the present strain measurement apparatus for concrete structures of the present invention is a suitable apparatus for carrying out the above-described measurement method, and is composed of easily available tools, members, etc., and by using this measurement apparatus, The above measuring method can be easily implemented.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining one Embodiment of the existing strain measuring method and measuring apparatus of the concrete structure of this invention, Comprising: Sectional drawing (a) which shows a mode that an auxiliary hole formation process is performed, and a mode that an embedded space formation process is performed Sectional drawing (b), sectional drawing (c) which shows the state after performing a strain gauge installation process, sectional drawing (d) which shows a mode that an outer core drilling process and the existing distortion calculation process are performed. It is a figure explaining other embodiment of the existing strain measuring method and measuring apparatus of a concrete structure, Comprising: Front view (a) which shows the external appearance of a strain gauge, Sectional drawing (b) which shows a mode that an embedded space formation process is performed It is sectional drawing (c) which shows the state after performing the strain meter installation process, and sectional drawing (d) which shows a mode that an outer core drilling process and the existing distortion calculation process are performed. It is a figure explaining an example of the existing strain measuring method and measuring apparatus of the conventional concrete structure, Comprising: The front view (a) which shows the external appearance of a strain gauge, The sectional view which shows the state where the strain gauge was installed in the embedded space ( b) A cross-sectional view (c) showing a state of drilling an outer core, and a cross-sectional view (d) showing a state of obtaining a strain signal and calculating an existing strain. It is a figure explaining other examples of the existing strain measuring method and measuring apparatus of the conventional concrete structure, Comprising: The front view (a) which shows the external appearance of a strain gauge, The cross section which shows the state by which the strain gauge was installed in the embedded space FIG. 2B is a cross-sectional view showing how a strain signal is acquired while drilling the outer core and the existing strain is calculated. It is the perspective view (a) which shows the external appearance of the concrete structure of a measuring object, and AA sectional drawing (b) which shows an internal structure.

  Hereinafter, an embodiment of an existing strain measuring method and measuring apparatus for a concrete structure according to the present invention will be described with reference to FIG. Here, the same components as those in the above-described conventional example are denoted by the same reference numerals, and description thereof is omitted.

  The present strain measuring apparatus according to this embodiment includes a small-diameter drill 34, an auxiliary core drill 36 that is an auxiliary drilling tool, a main core drill 28, a strain gauge 16 (type of FIG. 4A), and an analyzer 26. Has been.

  In addition, the present strain measurement method of this embodiment has three steps (guide hole forming step, embedded space forming step, strain gauge installation step) that are preparations for measurement, and two steps (outer core) that actually perform the measurement. Drilling step, existing strain calculation step), and the above-described existing strain measuring device is used in each step.

  As preparations for measurement, first, an embedded space forming step for forming a potted embedded space 12b inward from the first surface 12a (1) of the concrete structure 10, and the first surface 12a (1) A guide hole forming step for forming a guide hole 38 communicating from the opposite second surface 12a (2) to the inside of the embedded space 12b is performed. For example, as shown to Fig.1 (a), the through-hole 40 which reaches the 2nd surface 12a (2) from the 1st surface 12a (1) is drilled using the drill 34. Thereafter, as shown in FIG. 1 (b), using the auxiliary core drill 36, a circular groove-shaped inner core is formed inwardly from the outer peripheral portion of the opening end of the through hole 40 of the first surface 12a (1). 42 is drilled to a depth of about 3/5. Then, after the auxiliary core drill 36 is retracted, the concrete material 12 inside the inner core 42 is removed. Thus, a pothole-shaped embedded space 12b is formed, and a guide hole 38 that leads from the second surface 12a (2) to the deepest portion of the embedded space 12b is formed.

  When the embedded space 12b and the guide hole 38 are formed, the strain gauge 16 is prepared and the strain gauge installation process of installing the concrete gauge 10 is performed. First, the sensor body 18 is disposed in the embedded space 12b, and the cable 20 is pulled out of the second surface 12a (2) through the guide hole 38. And as shown in FIG.1 (c), the filling body 12 is filled with the fillers 24, such as mortar, and the sensor main body 18 is fixed to the measurement point in the concrete structure 10 by hardening this. This completes preparation for measurement.

  The measurement is performed by performing the outer core drilling step and the existing strain calculation step in parallel. First, an analysis device 26 for strain signal analysis is prepared, connected to the output end of the cable 20 and set to a state in which the strain signal can be received, and a strain signal in a stress unreleased state is acquired. Thereafter, as shown in FIG. 1 (d), the outer core 30 having a circular groove shape is drilled inwardly from the outer peripheral portion of the opening end of the embedded space 12b using the main core drill 28 (outer core drilling). Process). In the current strain calculation process, an analysis device is used to continuously acquire a strain signal that changes in the course of performing the outer core drilling process. At this time, since the value of the strain signal gradually changes until the depth of the outer core 30 exceeds the measurement point, whether the internal stress at the measurement point has been sufficiently released by analyzing the behavior of the strain signal. Make a decision. When it is determined that the internal stress at the measurement point has been sufficiently released, the outer core drilling process is terminated, the strain signal after stress release is identified from the strain signals acquired so far, and before and after the stress release. A predetermined calculation is performed using the distortion signal to calculate the existing distortion.

  As described above, according to the existing strain measurement method for a concrete structure of this embodiment, since the drilling of the outer core 30 and the acquisition of the strain signal can be performed continuously in parallel, Work efficiency is good. In addition, since the behavior of the strain signal that changes in the process of drilling the outer core 30 can be observed with higher accuracy, it is possible to appropriately determine whether or not the internal stress at the measurement point has been sufficiently released. Thus, it is possible to accurately detect the strain after releasing the stress at the measurement point. Then, by performing a predetermined calculation process using the detected strain signals before and after stress release, the existing strain can be calculated with high accuracy.

  In addition, the present strain measurement device for concrete structures of this embodiment is a device suitable for carrying out the above-described measurement method, and is composed of easily available tools, members, etc., and by using this measurement device, The above measurement method can be easily implemented.

  In the above description, the operation of drilling the outer core 30 is completed when the internal stress at the measurement point is sufficiently released, but may be continued without being completed. For example, if the outer core 30 is penetrated from the first surface 12a (1) to the second surface 12a (2), the inner part is cut off from the concrete material 12, so that the concrete core material can be collected easily. . The calculation of the existing strain performed in the above-described existing strain calculation step includes the mechanical property value such as the elastic coefficient of the concrete material 12 in the parameter. Therefore, if the elastic coefficient of the actual material is accurately known, the calculation accuracy can be improved. Further improvement can be achieved. Therefore, by directly measuring the elastic modulus etc. of the collected concrete core material with a dedicated testing machine, it is possible to accurately know the mechanical properties of the actual material, so the value of the existing strain calculated in the above existing strain calculation process By correcting this, a more accurate value of the existing distortion can be obtained.

  Next, another embodiment of the existing strain measuring method and measuring apparatus for a concrete structure will be described with reference to FIG. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The present strain measuring device of this embodiment is composed of a drill drill 34, an auxiliary core drill 36, a main core drill 28, a strain gauge 44 and an analysis device 46. The difference from the first embodiment is that a strain meter 44 and an analysis device 46 are provided instead of the strain meter 16 and the analysis device 26. As shown in FIG. 2A, the strain gauge 44 includes a sensor body 18 similar to the above, and a small radio 48 for externally outputting a strain signal detected by the strain sensor. Is connected to the sensor body 18 via a short cable 48a. The outer shape of the radio 48 is sized to fit inside the cutting edge of the main core drill 28. The analysis device 46 has the same function as the analysis device 26 described above, and further has a communication function that can receive the distortion signal output from the wireless device 48.

  The present strain measurement method of this embodiment has two steps (embedding space forming step, strain gauge installation step) that are preparations for measurement, and two steps that actually perform measurement (outer core drilling step, current strain calculation). The above-described existing strain measuring device is used in each process.

  In preparation for measurement, first, an embedded space forming step is performed. For example, as shown in FIG. 2B, the auxiliary core drill 36 is used to drill a circular groove-shaped inner core 42 inward from the first surface 12a (1) to a depth of about 3/5. To do. Then, the auxiliary core drill 36 is retracted, and the concrete material 12 inside the inner core 40 is removed. Thus, a pothole-shaped embedded space 12b is formed.

  When the embedded space 12b is formed, a strain gauge 44 is prepared and a strain gauge installation process is performed in which the strain gauge 44 is installed in the concrete structure 10. First, the sensor body 18 is disposed in the embedded space 12b, and the cable 48a is pulled out of the first surface 12a (1) through the embedded space 12b. Then, as shown in FIG. 2 (c), a filling material 24 such as mortar is filled in the embedded space 12 b and is cured to fix the sensor body 18 to a measurement point in the concrete structure 10. Further, the radio device 48 is arranged and fixed at the opening end of the embedded space 12b or in the vicinity thereof on the first surface 12a (1). When the external shape of the wireless device 48 is small, it may be arranged in the embedded space 12b. This completes preparation for measurement.

  The measurement is performed by performing the outer core drilling step and the existing strain calculation step in parallel. First, an analysis device 46 for strain signal analysis is prepared, the strain signal transmitted by the wireless device 48 is set in a receivable state, and a strain signal in a stress unreleased state is acquired. Thereafter, as shown in FIG. 2D, the outer core 30 having a circular groove shape is drilled inwardly from the outer peripheral portion of the opening end of the embedded space 12b using the main core drill 28 (outer core drilling). Process). In the existing strain calculation step, similarly to the above, the analysis device 46 is used to continuously acquire strain signals that change during the outer core drilling step. At this time, since the value of the strain signal gradually changes until the depth of the outer core 30 exceeds the measurement point, whether the internal stress at the measurement point has been sufficiently released by analyzing the behavior of the strain signal. Make a decision. When it is determined that the internal stress at the measurement point has been sufficiently released, the outer core drilling process is terminated, the strain signal after stress release is identified from the strain signals acquired so far, and before and after the stress release. A predetermined calculation is performed using the distortion signal to calculate the existing distortion.

  As explained above, according to the present strain measurement method for a concrete structure of this embodiment, the same effects as those of the first embodiment described above can be obtained. Further, unlike the first embodiment, the analysis device 46 and the strain gauge 44 are not directly connected by a cable, so that it is not necessary to form the guide hole 38 for passing the cable. Therefore, the guide hole forming step can be omitted and the working efficiency can be further improved. In the outer core drilling step, when cutting water is supplied to the cutting edge of the main core drill 28, the water is applied to the radio device 48. Therefore, it is preferable to select the waterproof radio device 48.

  In addition, the existing strain measuring method and measuring apparatus of the concrete structure of the present invention are not limited to the above embodiment. For example, a tool other than the above-described auxiliary core drill 36 may be used as an auxiliary drilling tool used to form an embedded space for accommodating a strain gauge. For example, a large-diameter drill or the like may be used. May be.

  When providing a guide hole for pulling out the cable of the strain gauge, the position of the second surface serving as the opening end of the guide hole is a position away from the first surface of the concrete structure, that is, the outer core is drilled. Any position that is away from the position may be used. Therefore, as in the above-described embodiment, the surface facing the first surface may be the second surface. For example, the surface intersecting the first surface is the second surface and drilled in an L shape. Alternatively, the first surface may be flush with the first surface, and the outer surface of the outer core may be used as a second surface to form a U-shape or a V-shape.

  The sensor body of the strain gauge is not limited as long as it can appropriately detect the strain at the measurement point in the concrete structure using the strain sensor, and other than the structure of the embedded sensor described in FIG. The structure may be changed. The strain sensor may be a sensor that detects strain or a sensor that detects stress. The analysis apparatus preferably has a configuration in which a data logger, a personal computer, and the like are combined. However, the analysis apparatus may be configured using other devices as long as the operation of the above-described invention can be realized.

  In addition to the concrete structure 10 described above, the measurement method and the measurement apparatus of the present invention are used in the same manner for the concrete materials having different external shapes and compositions and those having different numbers and arrangements of internal reinforcing bars. It goes without saying that you can do it.

DESCRIPTION OF SYMBOLS 10 Concrete structure 12a (1) Concrete material 1st surface 12a (2) Concrete material 2nd surface 16,44 Strain meter 18 Sensor main body 20,20a, 20b Cable 24 Filler 26,46 Analyzing device 28, 32 Main core drill 30 Outer core 34 Drilling hole 36 Auxiliary core drill (auxiliary drilling tool)
38 Guide hole 42 Inner core 48 Radio

Claims (4)

An embedding space forming step for forming a pothole-shaped embedding space inward from the first surface of the concrete structure;
A guide hole forming step of forming a guide hole leading from the second surface at a position away from the first surface to the inside of the embedded space;
A strain gauge comprising a sensor body having a strain sensor and a cable for externally outputting a strain signal detected by the strain sensor is prepared, and the sensor body is disposed in the embedded space, and the cable is A strain gauge installation step of pulling out the second surface through the guide hole, filling the embedded space in this state with the filler, and fixing the sensor body to the concrete structure;
Outer core drilling step of drilling a circular outer core using a main core drill, inward from the outer peripheral portion of the opening end of the embedded space on the first surface;
Prepare an analysis device for strain signal analysis, connect the analysis device to the output end of the cable to make the strain signal receivable, and use the analysis device to perform the outer core drilling step. A method for measuring the existing strain of a concrete structure, comprising: analyzing a behavior of the strain signal that changes in the course of performing and calculating an existing strain of the concrete structure. In the embedded space forming step,
2. The concrete according to claim 1, wherein a circular groove-shaped inner core is drilled inwardly from the first surface using an auxiliary core drill, and the concrete material inside the inner core is removed to form the embedded space. Current strain measurement method for structures. An auxiliary drilling tool for digging inwardly the first surface of the concrete structure to form a pothole-shaped embedded space;
A drill for forming a guide hole leading from the second surface away from the first surface to the interior of the embedded space;
A main core drill for drilling a circular groove-shaped outer core inward from the outer peripheral portion of the opening end of the embedded space on the first surface;
A strain meter including a strain sensor and a sensor main body fixed in the embedded space together with the strain sensor, and a cable for externally outputting a strain signal detected by the strain sensor;
With an analysis device for distortion signal analysis,
The cable is drawn out of the second surface through the guide hole;
The analysis device receives the strain signal through the cable and calculates the existing strain of the concrete structure by analyzing the behavior of the strain signal that changes in the process of drilling the outer core. An existing strain measurement device for concrete structures.   The auxiliary drilling tool is an auxiliary core drill for drilling a circular groove-shaped inner core inward from the first surface of the concrete structure, and the embedded space is formed by a concrete material in the inner core. 4. The existing strain measuring device for a concrete structure according to claim 3, which is the space after being removed.

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