JP2002054922A - Distortion sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distortion sensor capable of being easily attached to various structures and monitoring the displacement and deformation of the structure for a long period. SOLUTION: A metallic distortion storing sensor element 3 capable of storing the maximum distortion is mounted in a cut part 4 of a cylindrical sensor case body 2 having a hollow hole 2C for a lock bolt 22 and capable of allowing the force by the displacement and deformation to be measured to act between both end faces 2A-2B, and the deformation of the sensor case body 2 produced by the force acting on the sensor case body 2 is detected by the metallic distortion storing sensor element 3 as the distortion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain sensor used for measuring displacement deformation of a building structure or a civil engineering structure, and more particularly, to monitoring strain generated in various structures over a long period of time. The present invention relates to a suitable strain sensor.

[0002]

2. Description of the Related Art For example, in order to prevent the rock wall surface excavated in tunnel construction work from collapsing, a large number of rock bolts are driven at right angles to the rock wall surface after concrete is sprayed on the rock wall surface. And during the construction period,
In addition to the pull-out test of the installed rock bolts, the displacement of the tunnel shape is measured to monitor the change in the shape of the rock wall where the rock bolts are installed, and data on the measured strain is stored as necessary. .

As described above, various construction management systems from the start of construction of a building structure or a civil engineering structure to the completion thereof have been developed. It is recorded, and after completion, the data is filed and stored. It is preferable that the above-mentioned strain measurement of the structure is performed not only during the construction period but also continuously after the completion of construction, but conventionally it is not performed after the completion of construction for economic reasons. The obtained strain measurement data is left at least as long as no abnormalities occur in the structure, and there are few cases where the displacement of the structure is monitored sequentially.

[0004]

Therefore, after the completion of the construction, the presence or absence of the distortion of the structure and the amount of the distortion are not known. If the repair or restoration becomes necessary, it is necessary to refer to the displacement data acquired and stored during the construction, and to examine the method of detecting the displacement of the structure in an abnormal state. There is a problem that accurate repair work cannot be expected.

[0005] In addition, since the distortion and displacement of the structure at the time of a disaster such as destruction of the concrete such as concrete peeling or falling or the collapse of the bedrock cannot be grasped numerically, the destruction of the structure at the time of the disaster occurs. There is another problem that it is difficult to evaluate the state.

In order to solve these problems, if the maintenance of the structure is to be performed for more than ten years after the completion of the structure, the site where the maintenance is to be performed is very far from the inspection office. Performing the inspection manually requires enormous labor costs, which causes cost problems.

It is an object of the present invention to provide a strain sensor which can solve the above-mentioned problems in the prior art.

[0008]

According to the present invention, there is provided a strain sensor for measuring a strain of a structure, the strain sensor being capable of being inserted into a bolt and being capable of deforming the structure. Cylindrical sensor case main body for applying a force due to, and a metal strain storage sensor element capable of storing a maximum strain attached to the sensor case main body for detecting distortion generated in the sensor case main body And a strain sensor characterized by comprising:

As the metal strain memory sensor element, it is possible to use a strain-induced transformation (TRIP) type metal, for example, bainite steel, which is inexpensive and can hold the maximum value of the received strain.

The metal strain memory sensor element may be in the form of a strip-shaped thin plate, and may be attached to the outer periphery of the sensor case main body by using a fixing hardware and a sensor fixing nut to fix both ends thereof. In this case, a part of the outer peripheral portion of the sensor case main body is cut out, and the metal strain storage sensor element is mounted in the cutout formed by the cutout so as to protect the metal strain storage sensor element. Is also good.

The sensor case main body has a hollow hole,
A lock bolt and an anchor bolt can be passed through this hollow hole. After passing the lock bolt or the anchor bolt through the hollow hole, the sensor case main body is fixed to the lock bolt or the anchor bolt with a nut, whereby the displacement deformation or the like of the rock can be measured as a strain amount.

The metal strain memory sensor element is an element whose electric resistance changes according to the strain received. Therefore, a lead wire is electrically connected to both ends of the metal strain memory sensor element, and this lead wire is used for measurement. By connecting to an electric circuit or the like, the maximum value of the distortion received so far can be easily known.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of an embodiment of a strain sensor according to the present invention. The strain sensor 1 is for detecting a strain due to a force acting on the lock bolt or the anchor bolt, and has a hollow hole 2C for enabling easy attachment to the lock bolt or the anchor bolt.
And a sensor case main body 2 having a cylindrical shape having the following.

The sensor case main body 2 is made of a metal material having appropriate rigidity, and a force due to displacement deformation to be measured is applied between both end surfaces 2A-2B, and the sensor case main body 2 is deformed according to this force. It is becoming distorted.

In order to detect the strain generated in the sensor case main body 2, a metal strain memory sensor element 3 is provided in the sensor case main body 2.
Is attached. In the present embodiment, the sensor case main body 2 is formed with a notch 4 which is a semi-cylindrical concave portion by partially thinning a central portion thereof, and a bottom peripheral surface 4A of the notch 4 is formed. The metal strain memory sensor element 3 is mounted thereon. For this reason, the metal strain memory sensor element 3 is located inside the outer peripheral surface level of the sensor case main body 2, and it is possible to effectively prevent the metal strain memory sensor element 3 from being broken by contacting an external member.

The metal strain memory sensor element 3 has a strain-induced transformation (TRI) that can hold the maximum value of the received strain.
It is made of a P) type metal material and is in the form of a strip-shaped thin plate member. Then, both ends 3A, 3B of the metal strain memory sensor element 3 are attached to the bottom peripheral surface 4A by the sensor fixing hardware 5, 5.
Are fixed to the sensor case main body 2 at a predetermined interval from.

The sensor fixing metal 5 is electrically insulative and is fixed to the bottom peripheral surface 4A by bonding or other appropriate means, and is pressed against the lower metal 5A by a fixing nut 5C. And an upper metal part 5B made of a conductive material attached thereto. By firmly sandwiching both ends 3A and 3B of the metal strain memory sensor element 3 between the lower metal part 5A and the upper metal part 5B, the metal strain memory sensor element 3 is kept insulated from the sensor case main body 2. It is configured so that it can be fixed to the sensor case main body 2. Therefore, by electrically connecting lead wires (not shown) to the respective upper metal fittings 5B using the fixing nuts 5C, both ends 3A, 3B of the metal strain memory sensor element 3 are used using these lead wires.
Can be electrically connected to a predetermined measurement circuit.

Since the strain sensor 1 is configured as described above, when a force acts between both end surfaces 2A and 2B of the sensor case main body 2, the sensor case main body 2 is deformed in the axial direction according to the force. It will be. As shown in FIG. 1, the metal strain memory sensor element 3 is fixed to the sensor case main body 2 along the axial direction of the sensor case main body 2.
Is deformed in the longitudinal direction according to the deformation. Therefore,
The deformation of the sensor case main body 2 due to the force received between both end surfaces 2A and 2B of the sensor case main body 2 is detected as distortion by the metal strain storage sensor element 3, and the amount of the distortion can be measured. As already described, since the metal strain memory sensor element 3 can store the maximum strain received so far, if the strain sensor 1 is installed on an architectural structure or a civil engineering structure, the metal strain memory sensor element 3 can receive the maximum strain. The maximum distortion can be easily known at an appropriate timing.

In FIG. 2, the strain sensor 1 shown in FIG. 1 is set on a lock bolt driven on the inner wall surface of the tunnel,
An example of use in measuring displacement occurring on the inner wall surface of a tunnel is shown. In FIG. 2, reference numeral 21 denotes shotcrete sprayed on the excavated rock face of the tunnel. Rock bolts 22 are cast on a surface 21A of the shotcrete 21 serving as the inner surface of the tunnel to prevent the rock from collapsing. Have been. The tip of the lock bolt 22 penetrates the shotcrete 21 and is firmly cast on the bedrock 23 under the shotcast concrete 21, whereby the rockbolt 22 is firmly fixed to the bedrock 23 inside the tunnel. I have.

After the plate 24 and the strain sensor 1 are passed through the projecting portion 22A of the lock bolt 22 to the inside of the tunnel as shown in the figure, the strain sensor 1 is tightened by the fixing nut 25 so that the plate 24 It is firmly fixed to the lock bolt 22 so as to be pressed against the shotcrete 21 through the slab.

As can be understood from the above description, since the strain sensor 1 can be fixed to the protruding portion 22A of the lock bolt 22 as described above, not only a new lock bolt but also an existing lock bolt can be used. In this case, the strain sensor 1 can be easily attached.

If the strain sensor 1 is mounted on the lock bolt 22 as described above, and the surface 21A of the shotcrete 21 is displaced and deformed around the lock bolt 22, the strain sensor is displaced in accordance with the displaced deformation. The first sensor case main body 2 is deformed in the axial direction, and the resulting distortion of the sensor case main body 2 can be electrically detected by the metal strain storage sensor element 3. In order to measure the displacement of the surface 21A in this manner, a lead wire is electrically connected to both ends of the metal strain memory sensor element 3 as described above, and this lead wire is connected to a known measurement circuit (not shown). do it. In addition, if the measurement data indicating the measurement result is stored in the memory in the computer, the displacement of the surface 21A during the construction period of the tunnel can be monitored, and the measurement and monitoring are continuously performed even after the completion of the tunnel. be able to. Further, since the metal strain memory sensor element 3 stores the received maximum strain, the magnitude of the maximum strain can be measured at any time.

In FIG. 2, the measurement of the displacement deformation at one location on the inner peripheral wall surface of the tunnel has been described. If installed, the displacement of the entire inner circumferential surface of the tunnel can be measured and monitored. As a result, it is possible to quickly catch the signs of rock collapse in the tunnel and take safety measures early.

Further, since the distortion sensor 1 can store the maximum distortion, when an accident such as a dropping board occurs, it is possible to analyze the degree of occurrence of the distortion at that location at a later date and use it for investigating the cause of the accident.

FIG. 3 shows an example in which the strain sensor 1 is applied to the detection of a strain generated in a building structure.
In FIG. 3, 31 is a foundation concrete, 32 and 33 are anchor bolts embedded in the foundation concrete 31, and 34 is a steel column. A base plate 35 is fixed to a lower end of the steel column 34 by bolting. Anchor bolts 32 and 33 are passed through bolt holes (not shown) of the base plate 35, and the base plate 35 is fixed to the foundation concrete 31 by tightening nuts 36 and 37. It is firmly fixed.

In this example, between the nuts 36 and 37 and the base plate 35, the strain sensor 1 shown in FIG.
Is provided, so that the strain sensor 1 can detect the displacement deformation of the base plate 35 due to the force acting on the steel column 34.

Therefore, also in this case, the strain sensor 1 can be easily attached to the anchor bolts in the case of the existing one as well as in the case of the new one, and the displacement deformation generated in the building structure by the strain sensor 1 is shown in FIG. 2 can be measured and monitored in the same manner as in the case of FIG.

[0029]

According to the present invention, as described above, it is possible to monitor and measure displacement deformation in a building structure or civil engineering structure by attaching it to a lock bolt or anchor bolt regardless of whether it is new or existing. It becomes possible. As a result, displacement and deformation of building and civil structures during and / or after the completion of construction can be reliably checked, and predictions of the destruction of the structure and the collapse of bedrock can be made accurately. Can provide useful data for its repair and recovery work. In addition, since the maximum strain can be stored, if a strain sensor is installed in advance, changes in the amount of strain in each part can be periodically grasped even after completion, and the structure in the event of a disaster Evaluation of the destruction state of an object becomes easy. Further, since the strain sensor is mounted so as to be exposed to the outside, electrical connection can be easily made even afterward, and even if a lead wire breaks, it can be easily repaired, so that maintenance and inspection can be performed. Easy.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an embodiment of a strain sensor according to the present invention.

FIG. 2 is a diagram showing an example in which the strain sensor shown in FIG. 1 is set on a lock bolt and applied to detection of displacement deformation of an inner wall surface of a tunnel.

FIG. 3 is a diagram showing an example in which the strain sensor shown in FIG. 1 is applied to detection of displacement deformation generated in a building structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Strain sensor 2 Sensor case main body 3 Metal distortion memory sensor element 4 Notch 5 Sensor fixing hardware 21 Shotcrete 22 Lock bolt 24 Plate 25 Fixing nut 31 Foundation concrete 32, 33 Anchor bolt 34 Steel column 35 Base plate 36, 37 Nut

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01L 1/22 G01L 1 / 22Z (72) Inventor Michio Matsumoto 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo No. Taisei Corporation F term (reference) 2F049 BA02 CA01 CA05 DA04 2F063 AA25 BA17 BB10 BD12 DA02 DA05 DD01 EC03 EC05 EC22 FA00 KA10 2F069 AA68 GG54 HH30 KK10 MM04 2F070 AA20 CC01 2F076 BB09 BD02 BD04

Claims (3)

[Claims] 1. A strain sensor for measuring strain of a structure, comprising: a cylindrical sensor case main body that can be inserted into a bolt and applies a force due to displacement deformation of the structure; A strain sensor, comprising: a metal strain storage sensor element attached to the sensor case main body and capable of storing a maximum strain for detecting a strain generated in the case main body. 2. The strain sensor according to claim 1, wherein the metal strain memory sensor element is a strain-induced transformation type metal capable of holding a maximum value of the strain received. 3. The strain sensor according to claim 1, wherein a concave portion is provided on an outer peripheral portion of the sensor case main body, and the metal strain memory sensor element is mounted in the concave portion.