JP2001021651A - Method and device for inspecting inner wall of tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and quickly detect a crack or peeling of the concrete wall of a tunnel inner wall by applying FM laser radar technique. SOLUTION: A laser transmission signal in a high-frequency region of, for example, 200 THz is subjected to a high-speed frequency sweep of, for example, 100 GHz/ms in the horizontal direction of for example 360 deg. and a vertical direction of, for example, ±60 deg. toward a tunnel inner wall 2, a measurement value is displayed on a screen based on the correlation relationship between time delay T of a reception signal for the laser transmission signal and a frequency deviation width of Δf, thus detecting a crack or peeling of the concrete wall of the inner wall of the tunnel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-precision measurement system for an inner wall of a tunnel using an FM laser radar.

[0002]

2. Description of the Related Art It is known to transmit pulsed near-infrared radar light toward a target, receive reflected light, and measure the distance from the reciprocation time of the laser light to the target.

The FM laser radar applies the frequency of a laser transmission signal to a target at a high speed, obtains a received signal, and calculates the correlation between the time delay T of the received signal and the frequency of the transmitted / received signal by the frequency shift width Δf. It is known as a technique for measuring the distance to a target by using it.

[0004] Microwaves and millimeter waves are used by dividing the frequency band into satellite broadcasting, simple radio, and the like, and the distance of a target object is measured using this.

[0005]

It is required that the inspection of the inner wall of the tunnel be performed with high accuracy in order to ensure the safety of vehicles such as trains and automobiles passing through the tunnel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for inspecting a tunnel inner wall in which a concrete wall of a tunnel inner wall is cracked and / or peeled off with high accuracy and in a short time by applying FM laser radar technology. .

[0007]

Means for Solving the Problems Using an FM laser radar, the frequency of a laser transmission signal is swept over a wide range at a high speed, thereby performing high-accuracy distance measurement, and displaying the measured values three-dimensionally to form a tunnel inner wall. Cracks or delaminations of concrete walls. In this case, a laser signal is swept in a horizontal direction and a vertical direction with respect to the length direction of the tunnel to be transmitted in order to detect cracks and peeling of the arc-shaped tunnel inner wall. By such a sweep transmission, a crack or peeling of the concrete wall is appropriately displayed on the FM laser radar output screen, preferably on a screen using a three-dimensional image, and a predetermined crack width or crack depth and a state of the peeling are displayed. The alarm can be issued promptly by comparing with.

[0008] The present invention specifically provides the following method and apparatus.

According to the present invention, a laser transmission signal in a high-frequency region is swept at high speed in a horizontal direction and a vertical direction toward an inner wall of a tunnel, a time delay T of a reception signal with respect to the laser transmission signal, and a frequency shift width of the transmission / reception signal. Provided is a tunnel inner wall inspection method for detecting a crack or peeling of a concrete wall of a tunnel inner wall by displaying a measured value on a screen based on a correlation with Δf.

The present invention further provides a tunnel inner wall inspection method for sweeping a laser transmission signal at a high frequency within 360 ° in the horizontal direction and ± 60 ° in the vertical direction.

The present invention further provides a tunnel inner wall inspection method for automatically inspecting a tunnel inner wall while moving an FM laser radar at a constant speed in a tunnel length direction.

The present invention further provides a method for inspecting the inner wall of a tunnel, in which the width and depth of the crack are tertiarily displayed.

According to the present invention, a laser transmission signal in a high frequency region is transmitted at a high frequency toward an inner wall of a tunnel, and a time delay T of a reception signal with respect to the laser transmission signal and a frequency shift width Δf of the transmission / reception signal are based on a correlation. In addition, the present invention provides a tunnel inner wall inspection method for detecting cracks or peeling of a concrete wall of a tunnel inner wall.

According to the present invention, a laser transmission signal in a high-frequency region is transmitted at a high frequency toward an inner wall of a tunnel, and a time delay T of a reception signal with respect to the laser transmission signal and a frequency shift width Δf of the transmission / reception signal are based on a correlation. In addition, the present invention provides a tunnel inner wall inspection method that detects a peeling at every measurement point interval in a tunnel and generates an alarm signal by comparing with a set crack width or crack depth.

The present invention relates to a cart, and an FM mounted on the cart.
A laser radar and a control device thereof, and an image display device, wherein the FM laser radar sweeps a laser transmission signal in a high-frequency region in a horizontal direction and a vertical direction toward an inner wall of the tunnel, and performs a high-frequency sweep on the screen display device. Is a three-dimensional display of measured values based on a time delay T of a received signal with respect to a laser signal and a frequency shift width Δf of a transmitted / received signal, thereby detecting a crack or a peeling of a treat wall of the tunnel inner wall. An inspection device is provided.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the concept of an embodiment of the present invention, in which F is directed toward a tunnel inner wall 2 of a tunnel 1 to be inspected.
A laser transmission signal is transmitted from the M laser radar 3, and the frequency of the laser transmission signal is swept over a wide range at high speed. F
The M laser radar 3 is mounted on a truck 5, and the truck 5 runs at a constant speed in the tunnel. Reference numeral 4 denotes a measurement range at the time of one-point measurement. A laser transmission signal transmitted in this range is reflected from the tunnel inner wall 2 as a target, and a measurement value is obtained.

FIG. 2 schematically shows the entire configuration of a measuring apparatus including an FM laser radar 3 used in the embodiment of the present invention. The FM apparatus is mounted on a truck 5 traveling on a track 6 (or a road surface). The laser radar 3 and the control device 7 are mounted. The truck 5 includes a battery 8 and is controlled to run at a constant speed on the track 6. In this way, the automatic inspection of the entire inner wall of the tunnel is performed while moving at a constant speed. The measured values are signaled to the drawing display device 9.

FIGS. 3 and 4 show the principle of measurement.

FIG. 3 shows that the laser beam 11 from the FM laser radar 3 is transmitted to the concrete wall 12 and the reflected beam 13 reflected from the crack is received by the scanner mirror 14. In this case, the depth of the crack or peeling is defined as Δd.

FIG. 4 shows the relationship between the transmission signal and the reception signal. The frequency shift width between the transmission signal and the reception signal is Δf. A transmission signal in a high-frequency region, for example, 200 THz is swept in a high-speed frequency, for example, 100 GHz / ms, ± 60 ° (referred to as a high-speed frequency sweep).

After Δt (time delay T), the received signal is received by the scanner mirror 14. In this case, the following equation holds.

[0023]

(Equation 1)

Here, C is the speed of light.

Also,

[0026]

(Equation 2)

The measurement of Δf is performed using the correlation between Δd and Δf. That is, Δf is measured by causing transmission and reception signals to interfere. The received signal undergoes a frequency shift due to the time delay T due to the distance and the interference between the transmitted and received signals, and becomes a received signal as indicated by a dotted line.

Based on such a measurement principle, at the time of measuring one point in the tunnel, the scanner mirror 14 (FIG. 3) for measuring the inner wall of the tunnel is moved by 360.degree.首 Swing over the (measurement range).

The measured values are displayed in a three-dimensional screen on the screen display device 9 by three-dimensional display software, so that cracks and peeling of the concrete wall can be three-dimensionally detected. The screen display may be a cross-sectional image two-dimensionally indicating the width and the depth of the crack.

The main features and main specifications and effects of such an inspection method and an inspection apparatus are as follows.

Main features (1) High-speed frequency sweep in high-frequency range (200 THz)
(100 GHz / ms) High accuracy measurement. (2) Non-contact measurement is possible. (3) Can be measured on glossy surfaces (metal and white surfaces).

Main specifications and effects

[0033]

[Table 1]

According to this, one point measurement time is 0.5 s for the inner wall of a tunnel having a tunnel length of 10 km and a radius of 15 m.
The measurement can be completed in about 10 hours using three FM laser radars with ec, measurement point interval of 2 m.

FIG. 5 shows that after setting the measuring range and the measuring point interval,
An example is shown in which cracks and delamination of concrete walls are automatically measured and detected. Fig. 5 (a) shows a diagram in which the measurement range (indicated by a frame in the figure), the measurement direction (viewed in the direction of arrow A) and the measurement interval are set at a measurement distance of 6.5m, and cracks and peeling of the concrete wall are detected. Show. FIG. 5B is a diagram showing the width of the crack and the state of peeling on the screen display device 9. For example, crack width 0.2m
Cracks such as m, 1.0 mm are displayed as shown, and delamination is shown as shown. FIG. 5C is a diagram showing the depth of the crack. In the figure, the crack depth in the direction of the arrow A is displayed by color, for example, the concrete surface is displayed in red, the shallow portion of the crack is displayed in yellow, and the deep portion is displayed in blue to facilitate visual recognition. In addition, the example shown in FIGS.
It may be a dimensional display. The alarm signal may be generated by comparing the measured value with the set crack width or crack depth or by comparing with the size of the peeling. In this case, the presence / absence of the alarm signal is made at every measurement point interval in the tunnel, and the result is recorded in the memory.

[0036]

As described above, according to the present invention, it is possible to quickly detect cracks or peeling of the interior wall of the tunnel by using the FM laser radar, and to improve the safety of vehicles passing through the tunnel. Can be secured.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram of the overall configuration of an embodiment of the present invention.

FIG. 3 is a diagram showing a measuring method.

FIG. 4 is a diagram showing a measurement principle.

FIG. 5 is a diagram showing a measurement method and a measurement result.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tunnel, 2 ... Tunnel inner wall, 3 ... FM laser radar, 4 ... Measurement range, 5 ... Dolly, 6 ... Track, 7 ... Control device, 8 ... Battery, 9 ... Screen display device, 11 ... Laser beam, 12 ... Concrete wall, 13 ... reflected beam, 1
4: Scanner mirror.

Claims (7)

[Claims] 1. A high-speed frequency sweep of a laser transmission signal in a high-frequency region in a horizontal direction and a vertical direction toward an inner wall of a tunnel, and a time delay T of a reception signal with respect to the laser transmission signal and a frequency shift width Δf of the transmission / reception signal. A tunnel inner wall inspection method for detecting a crack or peeling of a concrete wall of a tunnel inner wall by displaying a measured value on a screen based on the correlation of the above. 2. A tunnel inner wall inspection method according to claim 1, wherein the laser transmission signal is swept at a high frequency within 360 ° in the horizontal direction and ± 60 ° in the vertical direction. 3. The tunnel inner wall inspection method according to claim 1, wherein the tunnel inner wall is automatically inspected while moving the FM laser radar at a constant speed in the tunnel length direction. 4. The tunnel inner wall inspection method according to claim 1, wherein the width and depth of the crack are displayed three-dimensionally. 5. A laser transmission signal in a high frequency region is transmitted at a high frequency toward an inner wall of a tunnel, and based on a correlation between a time delay T of a reception signal with respect to the laser transmission signal and a frequency shift width Δf of the transmission / reception signal. Tunnel inner wall inspection method for detecting cracks or peeling of concrete walls of tunnel inner walls. 6. A laser transmission signal in a high-frequency region is transmitted at a high frequency toward an inner wall of a tunnel, and based on a correlation between a time delay T of a reception signal with respect to the laser transmission signal and a frequency shift width Δf of the transmission / reception signal. A tunnel inner wall inspection method in which peeling is detected at every measurement point interval in a tunnel, and an alarm signal is issued by comparing with a set crack width or crack depth. 7. A trolley, an FM laser radar mounted on the trolley, a control device therefor, and an image display device, wherein the FM laser radar horizontally transmits a laser transmission signal in a high frequency region toward an inner wall of the tunnel. Direction and vertical,
The screen display device performs a high-frequency sweep, displays the measured values three-dimensionally on the basis of the time delay T of the received signal with respect to the laser signal and the frequency shift width Δf of the transmitted / received signal, and thereby displays the interior wall of the tunnel inner wall. A tunnel inner wall inspection device for detecting cracks or peeling of a tunnel.