JPH0439890B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for measuring changes in cracks that occur and progress due to various causes in various civil engineering and building structures. By attaching measurement bases that face each other on three or more different sides to each of the two structural blocks, and measuring the distance between them at any time,
It relates to a method that can accurately measure dimensional variations.

[Prior Art] In civil engineering or architectural structures, new cracks may occur due to earthquakes, ground subsidence, water pressure, deterioration of materials such as concrete, or poor construction.
Already existing cracks (including gaps, seams, etc.) may expand. Monitoring how these deformations progress and performing maintenance management to prevent structures from being destroyed is an extremely important issue in civil engineering. To this end, it is important to be able to measure crack fluctuations with extremely high accuracy of about 1/100 mm or less.

The conventional method for measuring the fluctuation of two structural blocks with a crack as a boundary is to fix a reference bolt, etc., to each structural block, and to stretch an Invar wire, etc. between them, and measure its length. There is a method of measuring the relative displacement between the two points to which bolts are attached due to changes. This method is based on the same principles as those used, for example, in landslide monitoring.

[Problems to be solved by the invention] Problems with cracks in civil engineering and architectural structures 2
The two structural blocks do not move only in the direction in which the crack expands, but work three-dimensionally. Therefore, if the three-dimensional behavior of the structural block cannot be accurately known, appropriate maintenance and management of the structure cannot be performed.

However, the conventional techniques described above can only measure linear relative distance fluctuations between both reference points of two structural blocks. Therefore, there is a drawback that it is not possible to measure how much the structural block relatively moves in which direction.

In addition, with the method of measuring the relative distance between two points by stretching a wire, the wire is always exposed on the surface of the structure, so problems such as getting caught on something are likely to occur, and management is troublesome. There are also some drawbacks.

It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to
It is an object of the present invention to provide a method for measuring crack fluctuations that can measure dimensional relative displacement with high precision and can perform stable measurements over a long period of time.

[Means for Solving the Problems] The present invention, which can achieve the above objects, has a specific shape for each of two structural blocks bordering on cracks (including gaps, joints, etc., hereinafter the same). The unique feature is that the measurement base is fixed and no wires are used.

Here, one measurement base has a shape with a recess or an opening, whereas the other measurement base has a structure that allows it to enter the recess or opening of the first measurement base with a margin. The two measurement bases are in a relationship such that three or more different sides face each other, and are attached to two structural blocks with the crack as a boundary, as described above. The three-dimensional relative displacement of the two structural blocks is determined by measuring the distance between the three or more opposing surfaces at any time, and the crack fluctuation is measured.

[Operation] Since the two measurement bases are each fixed to two structural blocks with cracks as boundaries, if the structural blocks are displaced, the measurement base will also be displaced accordingly. Since the two measurement bases face each other with a distance between them on three or more different sides, it is possible to accurately grasp the relative three-dimensional fluctuations of the two structural blocks by determining their relative distances. I can do it.

If two structural blocks bordering on a crack change by a relatively small distance, it can be considered that there is only a relative translational change. Three-dimensional relative displacement can be determined by measuring the distance between the two.

However, if the fluctuations of the structural blocks are extremely severe, the measurement base surfaces of the two structural blocks may undergo angular displacement due to uplift, subsidence, etc. with the crack as the boundary. In such cases, for example, it is possible to measure the inclination of the measurement base with respect to the vertical line, or measure at three or more different points on opposing surfaces so that changes in angle between the opposing surfaces can also be measured. It becomes possible to accurately grasp even the violent movements of structural blocks.

[Example] Fig. 1 is an explanatory view showing an example of a crack gauge to which the method of the present invention is applied, and Fig. 2 is an explanatory view showing the state during measurement. It is assumed that a crack 10 exists in a civil engineering structure or the like, and the crack 10 is divided into two structural blocks 12 and 14 with the crack as a boundary. A gate-shaped first measurement base 16 with a recess 18 is firmly fixed to one structural block 12 by bolts 20.
The first measurement base 16 is attached to the other structural block 14.
A second measuring base 22, which has a structure that allows it to enter the opening 18 with a margin, is similarly firmly fixed with bolts or the like. When these first and second measurement bases 16, 22 are installed in a place where temperature changes are severe, it is preferable to make them from a material with a small coefficient of thermal expansion, such as an amber alloy or ceramic. If it is installed in a place where temperature changes are small, such as deep underground, it may be made of ordinary metal.

The first measurement base 16 has a gate-shaped structure in which the upper ends of two upright parts 24 are connected to a horizontal frame part 26, whereas the second measurement base 22 has a tip end that enters the opening 18. It has a structure including an L-shaped part 28 and a hanging piece 30 erected from the tip thereof. and these two measurement bases 16, 22
are opposed in three different directions. That is, the inner surface of one of the upright portions 24 and the side surface of the L-shaped portion 28, the side surface of the horizontal portion 26 and the surface of the vertical portion 30, and the lower surface of the horizontal portion 26 and the L-shaped portion 28.
This is the upper surface of the mold part 28. Regarding these three sets of opposing surfaces, a displacement measuring device mounting portion is formed in advance on one member, respectively.

Here, the upright portion 24 of the first measurement base 16
, the vertical piece 30 of the second measurement base 22, and the first
Displacement measuring device mounting holes 34x, 34y, 34z are provided in the horizontal frame 26 of the measurement base 16, respectively, and dial gauges 32x, 32y, 3 are provided respectively.
The tip measurement part of 2z is configured to penetrate.
The mounting holes therefore correspond to the xyz rectangular coordinate axes shown in FIG.

Figure 2 shows the state in which dial gauges are attached to each corresponding part and are being measured. The distance between the inner surface of the upright portion 24 and the side surface of the L-shaped portion 28 (displacement in the x direction) is measured by the dial gauge 32
6 and the surface of the hanging piece 30 (displacement in the y direction) is measured, and the dial gauge 32 is also measured.
By z, the distance (displacement in the z direction) between the lower surface of the horizontal portion 26 and the upper surface of the L-shaped portion 28 is measured. Therefore, over time two structural masses 12, 14
When a relative displacement occurs, it becomes possible to accurately measure three-dimensional fluctuations in the crack.

If the crack fluctuations are relatively small, such a measurement is sufficient to determine the relative fluctuations of the two structural masses with sufficient accuracy. However, if the crack progresses further and the surfaces of the two structural blocks, that is, the mounting surfaces of the two measurement bases, move so as to cause a relative angular displacement, errors will occur in the measurement due to the influence of the rotation angle. . In such a case, as shown in FIG. 2, each measurement base 14, 22 is provided with an angle detection mechanism 36, and the inclination of each measurement base surface with respect to the vertical direction is measured in advance.
The angular displacement of the installation surfaces of both measurement bases can also be ascertained, thereby making it possible to determine accurate three-dimensional fluctuations.

FIG. 3 is an explanatory diagram showing another embodiment of a crack gauge to which the present invention is applied, and FIGS. 4A and 4B are a front view and a side view thereof, respectively. The basic idea is the same as in the previous embodiment.
The first structural block 12 has a crack 10 as its boundary.
The measuring base 42 of the other structural mass 14 is fixed to the measuring base 42 of the
A second measurement base 44 is fixed to. Here, it is firmly fixed with a weather-resistant adhesive material 46. The first measurement base 42 is the structural mass 12
The upright part 48 fixed to the side plate 50, the side plate 50 extending from the side surface, and the top plate 52 projecting to cover them are continuous and integral, and a concave part is formed by them. The measurement base 44 is a rectangular parallelepiped block that can fit comfortably within the recess. Therefore, in this case, the inner surfaces of the three plate-shaped portions constituting the first measurement base 42 and the outer surface of the second measurement base 44 face each other in three different directions. This example is significantly different from the previous example in that:
The point is that three or more displacement measuring device mounting holes 54, which are not lined up in a straight line, are provided on each opposing surface.

With this configuration, the distances can be measured at three points in each of the three directions x, y, and z, making it possible to measure not only the distance between the opposing surfaces but also the angular displacement.
Therefore, for example, even if the crack progresses as shown in FIG. 5 and the two structural blocks undergo a change that involves an angular change rather than a simple translational change, each opposing surface will change as shown in FIG. By inserting the dial gauge 32 at three or more points and measuring the distance, the distance between the facing surfaces can be determined including angular fluctuations, and all changes can be measured. In this case, there is no need to provide an angle measuring mechanism as shown in FIG. 2, and changes in angle can be measured using only the displacement measuring device, so the structure of the measuring base is simple and can be said to be extremely preferable.

Although two embodiments of the present invention have been described in detail above, it goes without saying that the present invention is not limited to only such configurations. It goes without saying that the shapes of the first measurement base and the second measurement base can be changed in various ways. For example, in Figure 1, the first
The measurement base may have an inverted L-shaped structure instead of a gate-shaped structure, or a mouth-shaped structure. In short, it is sufficient to use a combination of measurement bases having portions that face each other in three or more different directions. In addition to dial gauges, actuating transformers and optical displacement detectors can also be used as displacement measuring instruments. In any case, as long as the measurement points on each measurement base are determined in advance, crack fluctuations can be measured very easily by bringing in one portable displacement measuring device and sequentially measuring it.

[Effects of the Invention] As described above, the present invention is configured to measure the distance between opposing surfaces on three or more opposing surfaces using two measuring bases each fixed to two structural blocks bordering on a crack. , 3 of the two structural blocks
It is possible to measure relative dimensional displacement with high accuracy, accurately grasp the deformation of cracks, and prevent damage and destruction of civil engineering and building structures caused by cracks, allowing for appropriate maintenance management. It has excellent effects.

In addition, since the present invention only requires two measurement bases to be installed, stable measurement is possible over a long period of time, and measurement troubles are unlikely to occur, and maintenance of the measurement bases is almost unnecessary, which reduces costs. It has many excellent effects, such as being inexpensive and requiring no skill for measurement.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of a crack gauge to which the present invention is applied, FIG. 2 is an explanatory diagram showing a measurement situation using the same, and FIG. 3 is an explanatory diagram showing another embodiment of the crack gauge according to the present invention. Figure 4A is a front view, Figure 4B is a side view, Figure 5 is an explanatory diagram showing the state when the crack has expanded, and Figure 6
The figure is an explanatory diagram showing the interval measurement situation at that time. 10...Crack, 12,14...Structural block, 1
6... First measurement base, 18... Opening, 22
...Second measurement base, 32x, 32y, 32z
...Dial gauge, 34x, 34y, 34z...
...Hole for mounting a displacement measuring device.

Claims (1)

[Claims] 1. A first measuring base with a recess or opening is fixed to one of the structural blocks bordering the crack,
A second measurement base having a structure that can easily enter the recess or opening is fixed to the other structural block with the crack as a boundary so as to face each other on three or more different sides, and The method for measuring crack fluctuations is characterized in that the three-dimensional relative displacement of two structural blocks is determined by measuring the distance between the opposing surfaces of both measurement bases at any time.