JPH0772719B2 - Inspection method for surface anomalies in concrete structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is directed to, for example, surface anomalies of concrete structures such as buildings and towers or civil structures such as viaducts, tunnels and dams, that is, cracks. The present invention relates to a method for inspecting the exudation of rust and reinforced steel rust.

[Prior art and its problems] Conventionally, as a method of inspecting a concrete structure for cracks, the width and length of the cracks are written in a record book or marked at the cracked portions by visual inspection by the human naked eye. I was doing work such as taking photos.

However, visual inspection with the naked eye is very fatigued, and not only is it a harsh task, especially in places where the user must perform a visual check in an upward position, but also the tasks such as measurement, recording, marking, and shooting must be performed. However, there was a problem that it was complicated and time-consuming.

Also, especially in RC structures, brown rust often oozes out from the cracked parts, and searching for this rust leaching can be a clue to discover the rust of the reinforcing bar. There was a demand for an easy search method.

Conventionally, as a method for detecting cracks that occur in concrete, for example, as disclosed in Japanese Utility Model Laid-Open No. 56-116657, irradiate light from an irradiation optical fiber to a crack generation portion, and reflect the light. A light receiving optical fiber receives light and an image is displayed by an optical analysis device,
As disclosed in Japanese Patent Laid-Open No. 58-39934, a laser beam emitted from a laser light source is scanned on a surface of an object to be inspected by a scanning device including a rotating mirror and a parabolic mirror, and the reflected light is reflected by a fiber. To the integrating sphere by
There has been a photomultiplier that photoelectrically converts the electric signal and inputs the electric signal to a processing circuit to detect a defect.

However, the former technique is not only capable of detecting unless there is a change such as progress of cracks because it is merely irradiation of light, there is no means for scanning irradiation light, and the light receiving optical fiber is also fixed. Therefore, there is a problem that it is difficult to inspect the entire concrete surface, and the latter technique described above uses a large number of optical fibers arranged according to the scanning width and an integrating sphere to capture the reflected laser light. Therefore, there is a problem that the device is large, complicated and expensive.

[Object of the Invention] The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to detect cracks and leaching of reinforcing bar rust quickly, easily, and reliably. It is to provide a method of inspecting a surface abnormality in a concrete structure that can be performed.

[Structure of the Invention] A method for inspecting a surface abnormality in a concrete structure according to the present invention is a method in which a visible laser beam emitted from a light source is mechanically moved on a rotating mirror or a cylindrical prism and a conical mirror to form a concrete structure surface. Irradiating while scanning, the reflected laser light from the surface of the concrete structure is received by a light receiving element such as a CCD camera through the conical mirror, and is characterized by detecting cracks on the surface of the concrete structure. The visible laser beam emitted from the machine is irradiated while scanning the concrete structure surface by mechanically moving the rotating mirror or the cylindrical prism and the conical mirror, and the laser beam reflected from the concrete structure surface is irradiated on the conical surface. Light is received by a light receiving element such as a CCD camera through a mirror and a rust color identification filter, and To detect the exudation of the reinforcing bar rust on the surface of the structure In addition, by mechanically moving the mirror or prism,
It is characterized by scanning with a visible laser beam.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a light source 1 emits a visible laser beam. 2 is a rotating mirror,
It is rotating in the direction of the arrow at a predetermined speed. A conical mirror 3 irradiates the concrete surface 4, which is a subject, with the visible laser beam reflected by the rotating mirror 2. Reference numeral 5 is a light receiver such as a CCD camera.

Therefore, the visible laser beam emitted from the beam 1 is applied to the concrete surface 4 by the rotating mirror 2 and the conical mirror 3. In this case, since the rotating mirror 2 is rotating in the direction of the arrow, as shown in FIG. 2, the visible laser beam from the light source 1 moves in the longitudinal direction of the conical mirror 3 as the rotating mirror 2 rotates. Along which the illuminating light beam on the concrete surface 4 is scanned as shown. This scanning is repeated every time the plane of the rotating mirror 2 is changed.

Therefore, as shown in FIG. 3, when the conical mirror 3 is rotated by a slight angle for each scanning, the visible laser beam is scanned on the concrete surface 4 with a slight shift.

As described above, the concrete surface 4 is scanned while being scanned.
The visible laser beam radiated onto the concrete surface 4 is reflected again from the concrete surface 4 to the conical mirror 3.

At this time, if the crack C exists on the concrete surface 4, the reflected light becomes weak.

The reflected laser light is received by the light receiver 5 via the conical mirror 3.

Assuming that the intensity of the reflected laser light received by the light receiver 5 changes within a single scanning width, as shown in FIG. 4, the crack limit line is appropriately set based on many examples. By doing so, for example, it is possible to determine that a crack exists when the limit line is exceeded.

FIG. 5 shows another embodiment in which a cylindrical prism 6 is used in place of the rotating mirror 2 described above, and in the present embodiment as well, it is visible by rotating the cylindrical prism 6 by a predetermined angle. A laser beam can be scanned.

In the case of inspecting whether or not the reinforcing bar rust exudes from the cracked portion in parallel with the crack inspection,
As shown by the phantom line in the figure, a rust color identification filter 7 is installed in front of the light receiver 5 so that the light receiver 5 can identify only the rust color (brown).

There are two types of color identification, a mixed color matching method and a comparison method. In the mixed color matching method, the three primary colors are mixed in an appropriate ratio and compared to the ones to be measured, and then the stimulus is obtained. In the comparison method, one set of hundreds of sheets is standard. This is a method of making a color chart, exhausting various colors, and determining the color to be measured in comparison with this.

The cracked or rusted image signal received by the photodetector 5 is displayed on a monitor 9 via a data processing device 8 such as a personal computer or printed out by a printer 10 as shown in FIG. Or recorded by the memory means 11 as appropriate. In that case, it is also possible to project or print out the inspection site locally or entirely by developing software of the data processing device 8.

In addition, by periodically inspecting the same location of a certain structure and recording the data sequentially, by examining the change in the cracked state of the measured location, that is, the history, for example, the structure It is possible to know the state of stress applied to the.

[Effects of the Invention] (1) The reflected laser light from the surface of the concrete structure is
Since the light is received directly by the light receiving element such as a CCD camera through the conical mirror used for irradiation, it can be a simple and inexpensive device, and can be used in the field such as inspection of concrete structures. Are suitable.

(2) Since the reflected laser light from the concrete structure surface is made to be received by a light receiving element such as a CCD camera through a rust color identification filter, it is possible to reliably and easily detect the catastrophic rebar rust on the concrete structure surface. can do.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an apparatus for carrying out the method for inspecting the surface abnormality of a concrete structure of the present invention, FIG. 2 is an explanatory view showing the action of a rotating mirror, and FIG. 3 is a conical mirror. FIG. 4 is an explanatory diagram showing the action, FIG. 4 is an explanatory diagram showing the crack judgment from the inspection data, and FIG. 5 is an explanatory diagram showing another embodiment. 1 ... Light source, 2 ... Rotating mirror, 3 ... Conical mirror, 4 ...
… Concrete surface, 5… Light receiver, 6… Cylindrical prism, 7… Rust color identification filter, 8… Data processing device, 9… Monitor, 10… Printer, 11
…… Memory means, C …… cracking.

Claims (2)

[Claims] 1. A visible laser beam emitted from a light source is radiated while mechanically moving a rotating mirror or a cylindrical prism and a conical mirror while scanning the surface of a concrete structure, and a laser beam reflected from the surface of the concrete structure. Is detected by a light receiving element such as a CCD camera through the conical mirror to detect cracks on the surface of the concrete structure, and a method for inspecting a surface abnormality in the concrete structure. 2. A visible laser beam emitted from a light source is irradiated while scanning a concrete structure surface by mechanically moving a rotating mirror or a cylindrical prism and a conical mirror, and a reflected laser beam from the concrete structure surface. Is detected by a light receiving element such as a CCD camera through the conical mirror and the filter for identifying the rust color, and the oozing of the reinforced concrete rust on the surface of the concrete structure is detected to inspect the surface abnormality in the concrete structure. Method.