JP2003315214A - Sensor fitting structure to concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide structure for fitting a sensor which detects breakage of a tension material used for a prestressed concrete structure, so as to perform high-precision detection and to be exchangeable easily. <P>SOLUTION: The sensor fitting structure to the concrete structure is composed of a drilled hole 5 formed in the prestressed concrete structure 1 from its surface up to the periphery of the buried position of the tension material 2 towards the position, a cylindrical holder 8 stuck to the internal surface of the drilled hole 5 and made of a material whose elastic coefficient is smaller than that of concrete, a jig 11 to which the sensor 10 fitted in the cylindrical holder 8 in such a way as to be detachable or attachable freely is fitted toward the tension material 2 side at the tip of the jig, and a filler 16 which fills up the cylindrical holder 8. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for mounting a sensor for diagnosing deterioration on a concrete structure, and more particularly, an AE sensor for accurately detecting breakage of a tendon used in a prestressed concrete structure. The present invention relates to a mounting structure of the sensor of claim 1 to the prestressed concrete structure.

[0002]

2. Description of the Related Art For example, a concrete structure such as a road bridge or a railway bridge is subjected to a repeated load over time, so a prestressed concrete structure in which a tension material is embedded is used. In such a prestressed concrete structure, it is very important to detect the breakage of the tendons because the collapse of the entire structure can be predicted in advance.

Here, as a method of detecting the breakage of the tension material embedded inside the prestressed concrete structure, an acoustic emission (hereinafter abbreviated as AE) method has been conventionally known. This A
The E method is a method of diagnosing an abnormality such as a concrete structure by detecting an elastic wave generated by energy released when a solid is deformed or broken and analyzing the elastic wave.

When it is attempted to detect the breakage of the tension material embedded in the prestressed concrete structure by the AE method, most of the conventional methods have hitherto been performed on the concrete structure near the portion where the tension material is embedded. On the surface,
It has been done to attach an AE sensor that detects elastic waves.

[0005]

Here, generally, a PC steel rod or a PC steel wire is used as the above-mentioned tension material for exerting a prestress on a concrete structure, and in recent years, the adhesion to the structure has been improved. More wire is used than good PC steel.

When a PC steel bar is used as a tension material, a large amount of energy is released when the bar is broken, and a strong elastic wave propagates in the concrete structure. Therefore, even a sensor mounted on the surface of the concrete structure, The detection was possible enough. However, in the case of a PC twisted wire, the breakage of the PC twisted wire does not occur at once, but one or several wires gradually break, so that a large amount of energy is not released and a weak elasticity The waves will only propagate in the concrete structure. Therefore, even if the PC rope is actually broken, the sensor attached to the surface of the concrete structure may not be able to detect the elastic wave due to the break, and the PC rope is frequently used. In recent years, it has become a big issue.

Further, since the concrete structure is outdoors, the sensor mounted on the surface of the concrete structure is
For example, the sound of rain and wind was picked up, and that sound became noise, which reduced the accuracy of elastic wave detection due to the breaking of the tension material, and the sensor mounted on the surface of the concrete structure properly maintained the temperature change. It is exposed to wind and rain, and it is also corroded by salt along the sea,
There was also the problem of severe deterioration and damage.

On the other hand, it is important that the sensor has a long life and is easy to replace in order to construct a system for continuously monitoring the breakage of the tendons for a long period of time.

Therefore, an object of the present invention is to detect a sensor such as an AE sensor for detecting breakage of a tendon used in a prestressed concrete structure with high detection accuracy.
Another object of the present invention is to provide a structure that can be easily attached to the concrete structure.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a prestressed concrete structure from a surface to a position where a tension member is embedded to a position near the position where the tension member is embedded, and a hole formed in the structure. A tubular holder made of a material having a smaller elastic coefficient than concrete fixed to the inner surface of the hole, and a jig having the sensor detachably mounted in the tubular holder attached to the tip toward the tension material side. When,
A sensor mounting structure was formed on a concrete structure consisting of a filler loaded in the cylindrical holder.

According to the above-described sensor mounting structure for a concrete structure according to the present invention, the sensor is mounted in the drilled hole near the embedding position of the tension material, such as the surface of the protection grout of the tension material. Sound such as rain and wind is rarely picked up, and the sensor is located in the vicinity of the tension material. Therefore, even if the tension material is a PC steel strand, a weak elastic wave based on the breakage can be accurately detected. It becomes possible. Further, since the sensor is mounted in the drilled hole by a cylindrical holder fixed to the inner surface of the drilled hole with an adhesive or the like and a jig detachably mounted in the cylindrical holder, the sensor can be easily replaced. Will be things. Furthermore, since the cylindrical holder fixed to the inner surface of the drilled hole is formed of a material having a smaller elastic coefficient than concrete, for example, plastic, and the filling material is loaded inside the cylindrical holder, the cylindrical holder is not affected by the displacement of concrete. It easily follows and is less likely to peel off from the inner surface of the hole, and the filler loaded inside the cylindrical holder blocks moisture and salt entering from the outside, so it is installed inside the hole. The above-mentioned sensor and the tension member located near the drilled hole are sufficiently protected from the external environment. From the above, the sensor mounting structure for a concrete structure according to the present invention has a sensor for detecting breakage of a tension member used in the concrete structure, which can be accurately detected and easily exchanged with the concrete structure. It is possible to build a system that can be attached to the, and keeps monitoring the breaking of the tendons for a long period of time.

Here, in the present invention, it is preferable to use a hole for inspecting the filling condition of the grout that protects the tension material as the hole for mounting the sensor. This is because the hole for inspecting the filling state of the grout is a hole that reaches the protective grout of the tension material that is very close to the position where the tension material is embedded. It is preferable because breakage can be detected with high precision, there is no need to form a new hole, and the influence on the structure can be minimized.

The concrete structure referred to in the present invention is not particularly limited as long as it is a prestressed concrete structure in which a tension material is used, but it is not limited to bridges such as roads and railways, high-rise buildings, dams, Examples include tunnels. Further, the sensor referred to in the present invention is a sensor that detects an elastic wave generated by energy released when a solid is deformed or destroyed, and includes an AE sensor, an ultrasonic sensor, an acceleration sensor,
Examples include microphones. Furthermore, the filler used in the present invention is an ointment-like substance that does not harden, and examples thereof include mineral oil-based grease, silicon-based grease, and fluorine-based grease.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A sensor mounting structure for a concrete structure according to the present invention described above will be described below in detail with reference to the drawings.

FIGS. 1 to 3 show the concept of an embodiment in which a sensor mounting structure for a concrete structure according to the present invention is applied to an AE sensor mounting for a prestressed concrete structure such as a road bridge or a railway bridge. FIG.

In the figure, reference numeral 1 denotes a concrete structure, and the concrete structure 1 is prestressed by a tension member 2 made of PC steel strands. The tension member 2 is protected by the grout 4 with which the sheath tube 3 is filled, and is also integrally embedded in the concrete structure 1 through the grout 4.

The concrete structure 1 is formed with a hole 5 for inspecting the filling state of the grout 4. The drilled hole 5 reaches the sheath tube 3, and the sheath tube 3 is formed with a hole 6 communicating with the drilled hole 5.

The outer peripheral surface of the cylindrical holder 8 is integrally fixed to the inner peripheral surface of the hole 5 with an adhesive agent 7.
The cylindrical holder 8 is formed of a non-metallic material having a smaller elastic coefficient than concrete, for example, plastic, into a cylindrical shape with both ends open, and a female screw 9 is formed on the inner peripheral surface of the rear end thereof as shown in FIG. It is carved.

A jig 11 having an AE sensor 10 attached to its tip is mounted in the cylindrical holder 8, and the AE sensor 10 is brought into close contact with the surface of the grout 4 through the hole 6 by the jig 11. It is mounted in the drilled hole 5 in this state. This jig 11 is made of a non-metallic material, such as plastic, which has an elastic modulus smaller than that of concrete, as shown in FIG. 3, and has a front end cylindrical portion 11a to which the AE sensor 10 is attached, and a rear end cylindrical portion 11b which functions as a lid. , And a connecting portion 11c that connects both of the columnar portions 11a and 11b is integrally formed. The AE is attached to the tip cylindrical portion 11a.
A concave portion 12 for mounting the sensor 10 (this concave portion 12 is closed by another member when used at the time of grout filling as described later) is formed, and the rear end cylindrical portion 11b has an outer peripheral surface thereof. A male screw 13 that is screwed into the female screw 9 of the cylindrical holder 8 is engraved, and a knob 14 is formed on the rear end surface thereof. In addition, the fine hole 15 into which the lead wire 10a of the AE sensor 10 is inserted is formed by the tip cylindrical portion 1
1a, the connecting portion 11c, and the rear end cylindrical portion 11b are formed.

Further, the inside of the cylindrical holder 8 is prevented from invading water, salt and the like into the cylindrical holder 8.
It is filled with a filler 16 which is an ointment-like substance such as silicone grease.

Next, an example of an attaching procedure for realizing the above-described sensor attaching structure to the concrete structure according to the present invention will be described. In this example, when constructing a concrete structure and using a hole for inspecting the grout filling condition before filling the grout, or after constructing the concrete structure, the grout filling is incomplete. Yes, this is an example of using a drilling hole for inspecting the grout filling condition that requires new grouting.

First, a hole 5 for inspecting the grout filling condition
Then, the cylindrical holder 8 is fixed by using the adhesive 7.

Subsequently, the jig 11 is inserted into the fixed cylindrical holder 8 and the rear end cylindrical portion 11 of the jig 11 is inserted.
The jig 11 is mounted in the cylindrical holder 8 by screwing the male screw 13 formed in b into the female screw 9 formed in the cylindrical holder 8. At this time, by using the knob portion 14 formed on the rear end cylindrical portion 11b of the jig 11, the attachment can be easily performed. The concave portion 12 for mounting the AE sensor formed on the distal end cylindrical portion 11a of the jig 11 is attached to the cylindrical holder 8 in a state where the distal end surface is closed by another member so as to be a flat surface.

Subsequently, the grout 4 is filled into the sheath tube 3 in which the tension member 2 is arranged through a separately provided grout injection hole (not shown).

After the filled grout 4 is cured, the jig 11 mounted on the cylindrical holder 8 is removed and the filling state of the grout 4 is inspected.

After confirming that the grout 4 is well filled, the grease 16 is filled in the cylindrical holder 8 and the jig 11 in which the AE sensor 10 is mounted in the recess 12 is formed in the same manner as described above. It mounts in the cylindrical holder 8 by the method.

As a result, the AE sensor 10 can be mounted in the drilled hole 5 in a state in which the AE sensor 10 is in close contact with the grout 4 that protects the tension member 2, and the elasticity propagating in the concrete structure 1 detected by the AE sensor 10 is maintained. Waves are shown in Figure 1 and Figure 2.
Via the lead wire 10a as shown in FIG.
0, and the elastic wave detected by the AE sensor 10 is evaluated by the amplifier, A / D converter, control unit (neither shown), etc. provided in the measurement box 20, and the elastic wave of the tension member 2 is detected. If it is due to breakage, the warning light 21 is turned on to notify the manager of the structure.

Although one embodiment of the structure for mounting a sensor on a concrete structure according to the present invention has been described above, the present invention is not limited to the above-mentioned embodiments, and the technical idea of the present invention is not limited thereto. It goes without saying that various modifications and changes can be made within the range.

For example, in the above-described embodiment, the description has been given of the case where the hole for mounting the sensor is the hole 5 for inspecting the grout filling condition. Drilling holes that approach the buried position may be newly drilled for sensor mounting,
In this case, the above paragraph numbers [0022] to [002]
4) is attached with the grouting step described in [4] omitted. As described above, the sensor may be an acceleration sensor or an ultrasonic sensor instead of the AE sensor 10. Further, in the above-described embodiment, the jig is detachably mounted on the cylindrical holder, and the female screw 9 formed on the cylindrical holder 8 is screwed with the male screw 13 formed on the jig 11. Although the structure has been described, this is merely an example, and for example, a structure in which the annular convex portion formed on the outer peripheral surface of the jig is fitted into the annular concave portion formed on the inner peripheral surface of the cylindrical holder, or Structure using various fasteners using the clamp mechanism,
Various known structures can be adopted in which the jig can be easily attached and detached to the cylindrical holder.

[0030]

According to the sensor mounting structure for a concrete structure according to the present invention described above, a sensor for detecting breakage of a tendon used in a prestressed concrete structure is detected in the concrete structure. There is an effect that the system can be installed with high accuracy and easy replacement, and that a system for continuously monitoring the breakage of the tendon material for a long period of time can be constructed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view conceptually showing an embodiment of a sensor mounting structure for a concrete structure according to the present invention.

FIG. 2 is a vertical sectional view conceptually showing an embodiment of a sensor mounting structure for a concrete structure according to the present invention.

FIG. 3 is an exploded perspective view conceptually showing an embodiment of a sensor mounting structure for a concrete structure according to the present invention.

[Explanation of symbols]

1 concrete structure 2 tension material 3 sheath tube 4 grout 5 drilling 6 holes 7 adhesive 8 tubular holder 9 female screw 10 AE sensor 10a lead wire 11 jigs 12 recess 13 male screw 14 Picking part 15 pores 16 Filling material 20 measuring boxes 21 Warning light

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Joe Hamada             1-16-6 Kitaotsuka, Toshima-ku, Tokyo Dopy             Construction Industry Co., Ltd. Technical Center F-term (reference) 2G024 AD34 BA12 BA21 CA13 DA01                       FA02                 2G050 AA02 BA12 CA01 DA01 EB10                       EC06

Claims (2)

[Claims] 1. A mounting structure for a sensor for detecting breakage of a tension member embedded in a prestressed concrete structure, which is drilled from the surface of the concrete structure toward a position where the tension member is embedded to a position near the position. A hole, a cylindrical holder formed of a material having a smaller elastic coefficient than concrete fixed to the inner surface of the hole, and the sensor detachably mounted in the cylindrical holder facing the tension material side. A sensor mounting structure for a concrete structure, comprising a jig mounted at a tip and a filler loaded in the cylindrical holder. 2. The sensor mounting structure for a concrete structure according to claim 1, wherein the hole is a hole for inspecting a filling state of grout that protects a tension member.