Tunnel construction methods

Abstract

To propose a tunnel construction method that allows tunnel construction to be carried out while visually confirming measurement results using a 3D scanner.SOLUTION: A tunnel construction method comprises a first excavation step in which a measurement target section is excavated, a first measurement step in which point cloud data on a tunnel wall surface is measured using a 3D scanner in the measurement target section to obtain first point cloud data, a second excavation step in which a section in front of the measurement target section is excavated, a second measurement step in which point cloud data on the tunnel wall surface is measured with the 3D scanner in the measurement target section to obtain second point cloud data, a differential point cloud data creation step of calculating the difference between the first point cloud data and the second point cloud data, and an augmented reality display step of creating an augmented reality model using the difference and displaying the augmented reality model on display means.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a tunnel construction method using a 3D scanner.

Background Art

[0002] In tunnel construction, the safety and quality of the construction are ensured by periodically measuring the displacement of the ground and the inside of the tunnel (A measurement) and the stress of support members and the like (B measurement). By periodically measuring the tunnel conditions, it is possible to evaluate or predict the ground conditions near the measurement points and to determine the suitability of the support structure. In A measurement, it is common to set a control section at regular intervals (20 to 30 m) and measure the coordinates of targets provided on the top and side walls of the tunnel at the control section using a distance measuring instrument such as a total station (see, for example, Patent Document 1). In conventional displacement measurement, it is common to perform measurement at about 5 points in one section. However, it is difficult to comprehensively grasp the internal displacement of the tunnel only with the measurement data of 5 points. Therefore, in some cases, measurement of three-dimensional point cloud data using a 3D scanner is performed. However, even in the measurement using a 3D scanner, the evaluation remains two-dimensional, and a three-dimensional visualization method has not been established. Therefore, the present applicant has disclosed a tunnel construction method that facilitates a visual comparison between the face and the measurement data by projecting an image file created from measurement data onto the face using a projector as a three-dimensional visualization method (see Patent Document 2). The tunnel construction method of Patent Document 2 enables information sharing before work because image data is projected onto the face using a projector. On the other hand, it is difficult to perform a collation check on the face during work. In addition, although projection of an image file by a projector is possible for a face having a substantially planar shape, it is not suitable for a face having a curved surface such as a tunnel wall surface.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-99670 [Patent Document 2] Patent No. 6959020 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] From this perspective, the present invention aims to propose a tunnel construction method that enables tunnel construction while visually confirming the measurement results using a 3D scanner. [Means for solving the problem]

[0005] The tunnel construction method of the present invention for solving the above problems comprises: a first excavation step of excavating a section to be measured; a first measurement step of obtaining first point cloud data by measuring point cloud data of the tunnel wall surface using a 3D scanner in the section to be measured; a second measurement step of obtaining second point cloud data by measuring point cloud data of the tunnel wall surface again using a 3D scanner in the section to be measured; a difference point cloud data creation step of calculating the difference between the first point cloud data and the second point cloud data; and an augmented reality display step of creating an augmented reality model using the difference and displaying the augmented reality model on a display means. In the second measurement step, measurements are taken with a target installed on the tunnel wall. In the augmented reality display step, the target appearing in the augmented reality model is superimposed on the target installed on the tunnel wall, thereby displaying an image of the augmented reality model superimposed on the tunnel wall on the display means. Furthermore, the timing of the second measurement process is not limited to after the first measurement process; for example, it may be performed after the first measurement process, when work that was interrupted for some reason is resumed. Also, the second measurement process may be performed after the first measurement process, or after the second excavation process, which excavates the section ahead of the measurement target section. If the first excavation process excavates the upper half of the measurement target section, the second measurement process may be performed after the second excavation process, which excavates the lower half of the measurement target section. Moreover, the second measurement process may be performed after the second excavation process, which performs invert excavation of the section excavated in the first excavation process (the measurement target section). Furthermore, if a spraying process in which sprayed concrete onto the exposed ground surface resulting from the first excavation process is provided before the first measurement process, the difference represents the amount of ground displacement.

[0006] This tunnel construction method uses a 3D scanner to acquire three-dimensional point cloud data, making it possible to capture continuous data that could not be captured by measurements using a total station. Furthermore, an augmented reality model can be overlaid on the photographic data of the tunnel face and tunnel walls and displayed on a display device such as a tablet. Therefore, tunnel construction can be carried out while visually confirming the construction status and displacement. Furthermore, the system may include an initial measurement step, in which the exposed ground surface from the first excavation step is measured using a 3D scanner to obtain initial point cloud data, and a spraying step, in which sprayed sprayed concrete onto the exposed ground surface from the first excavation step, prior to the first measurement step. In this case, the spraying thickness can be calculated from the difference between the initial point cloud data and the first point cloud data. Alternatively, the initial point cloud data can be used to determine the amount of over-excavation and contact. Furthermore, if the system includes a step for verifying the completed shape by calculating the difference between the first point cloud data and the design cross-section, it becomes possible to determine the amount of over-excavation and contact, and to verify the completed shape. [Effects of the Invention]

[0007] According to the tunnel construction method of the present invention, tunnel construction can be performed while visually confirming the measurement results using a 3D scanner. [Brief explanation of the drawing]

[0008] [Figure 1] This flowchart shows the procedure for a tunnel construction method according to an embodiment of the present invention. [Figure 2] This is an illustrative diagram showing the difference between the first and second point cloud data. [Figure 3]This is an illustrative image showing an augmented reality model displayed on a display device superimposed on photographic data of the tunnel wall. [Figure 4] This is an explanatory diagram showing an overview of tunnel construction methods for other forms, where (a) is the first measurement process and (b) is the second measurement process. [Modes for carrying out the invention]

[0009] In an embodiment of the present invention, a tunnel construction method is described in which, in the construction of a mountain tunnel, instead of A measurement using a total station, the shape of the tunnel wall is periodically measured using a 3D scanner to check the internal displacement while excavating. This embodiment describes the case of tunnel excavation using the blasting method. Tunnel excavation consists of a loading step in which explosive holes are drilled in the tunnel face and explosives are loaded into the holes, an excavation step in which the rock mass is fractured by blasting the explosives and excavation is carried out, a spoil removal step in which spoil (a general term for "rocks, minerals, soil, etc." generated by blasting) is removed, a spraying step in which sprayed sprayed concrete onto the exposed ground surface after excavation, and a rock bolt step in which rock bolts are installed. The excavation length of one cycle is approximately 1.0 to 1.2 m. In some cases, a steel support step may be required in which steel supports are installed at the same time as the spraying step.

[0010] Figure 1 shows the tunnel construction method. As shown in Figure 1, the tunnel construction method of this embodiment comprises a first excavation process S1, an initial measurement process S2, a spraying process S3, a first measurement process S4, a second excavation process S5, a second measurement process S6, a difference point cloud data creation process S7, an augmented reality display process S8, and a completed work confirmation process S9. The first excavation process S1 is the process of excavating the section to be measured. That is, the loading step and the excavation step are carried out to excavate the tunnel in the section to be measured. The initial measurement step S2 is the process of obtaining initial point cloud data by measuring point cloud data of the tunnel wall surface using a 3D scanner in the section to be measured. In other words, the three-dimensional coordinates of the tunnel wall surface (ground surface) are measured using a 3D scanner. The measurement results (initial point cloud data) are stored in a storage device such as a computer.

[0011] Measurements using a 3D scanner are performed after removing excavation equipment from the tunnel face and installing the 3D scanner inside the borehole. The 3D scanner works by irradiating the object to be measured (tunnel wall) with laser light and analyzing the time it takes for the reflected laser light to reach the 3D scanner, as well as the angle of the reflected light, to acquire three-dimensional data (shape) of the object. In other words, measurements using a 3D scanner capture the planar shape by processing a large amount of point cloud data.

[0012] The shotcrete application process S3 is the process of spraying shotcrete onto the exposed ground surface during the first excavation process (shotcrete step). The shotcrete is applied to the entire tunnel wall surface to ensure the required thickness is achieved. In addition, steel supports may be installed during the shotcrete application process S3 as needed. The first measurement step S4 is the process of obtaining first point cloud data by measuring point cloud data of the tunnel wall surface using a 3D scanner in the measurement target section. That is, the three-dimensional coordinates of the tunnel wall surface (surface of sprayed concrete) are measured using a 3D scanner. The first measurement step S4 is performed after the spraying machine has been moved away from the tunnel face. The measurement results (first point cloud data) are stored in a storage device.

[0013] The second excavation process S5 is a process in which excavation is carried out in the section ahead of the section to be measured. That is, the loading step and the excavation step are performed to excavate the tunnel in the second excavation section ahead of the section to be measured. The second measurement step S6 is a step in which point cloud data of the tunnel wall surface is measured using a 3D scanner in the measurement target section to obtain second point cloud data. That is, the three-dimensional coordinates of the tunnel wall surface (ground surface) are measured using a 3D scanner. The measurement results (second point cloud data) are stored in a storage device. In this embodiment, the second measurement step S6 is performed after the spraying concrete has been sprayed in the second excavation section and the spraying machine has been moved away from the tunnel face. When measuring the tunnel wall surface using a 3D scanner in the second measurement step S6, a target is set up on the tunnel wall surface. The material and shape of the target are not limited as long as it is possible to form a convex surface that has a larger displacement than other parts of the tunnel wall surface. In this embodiment, the second point cloud data is obtained with a paper plate attached to the tunnel wall surface as the target.

[0014] Step S7, which involves creating differential point cloud data, is the process of calculating the difference between the first point cloud data and the second point cloud data. By calculating the difference between the first and second point cloud data, the amount of ground displacement between the first excavation step S1 and the second excavation step S5 is calculated (see Figure 2). The differential data (amount of ground displacement) is stored in a storage device. Figure 2 is an illustrative diagram showing the amount of ground displacement. In this embodiment, surface data (plane data) is created from each point in the first point cloud data, and the difference data is calculated by determining the distance between "each point in the second point cloud data" and "the surface data from the first point cloud data." However, the method for creating the difference data is not limited. The augmented reality display step S8 is a step of creating an augmented reality model using the difference data and displaying the augmented reality model on the display means. The display means in the present embodiment uses a mobile terminal such as a tablet terminal. In the augmented reality display step S8, an image obtained by superimposing the augmented reality model on the photographed image of the tunnel wall surface is displayed on the display means (see FIG. 3). That is, even during work near the face, an image obtained by superimposing the tunnel wall surface and the measurement data can be confirmed on the display means. At this time, it is desirable to display the magnitude of the displacement amount in terms of color. When superimposing the augmented reality model on the photographed image of the tunnel wall surface, the convex surface of the target appearing in the augmented reality model may be superimposed on the target installed on the tunnel wall surface. Note that FIG. 3 is an image diagram of the image displayed on the display means. The image obtained by superimposing the tunnel wall surface and the measurement data can be confirmed by a plurality of people simultaneously at a plurality of locations.

[0015] The finished shape confirmation step S9 is a step of calculating the difference between the measurement data (initial point cloud data, first point cloud data or second point cloud data) and the designed cross section. That is, by calculating the difference between the initial point cloud data and the designed excavation cross section, the over-excavation amount and the hitting amount of the excavation cross section with respect to the designed excavation cross section are calculated. By superimposing this on the photographed image of the tunnel wall surface, the over-excavation amount and the hitting amount with respect to the designed cross section can be visualized. As a result, if the amount of over-excavation and hitting can be grasped comprehensively, it can be used for calculating the amount of sprayed concrete and for managing over-excavation after the next excavation process (adjusting the angle of drilling, the number of holes, and the amount of explosive charge). If the excavation cross section can be constructed in a shape that is infinitely close to the designed cross section, effects such as reduction of the amount of sprayed concrete and the amount of slip generation, or improvement of the construction cycle time can be expected. Alternatively, the over-excavation amount and the hitting amount with respect to the designed spraying cross section may be calculated by calculating the difference between the first point cloud data or the second point cloud data and the designed spraying cross section. If the over-excavation amount and the hitting amount of the tunnel wall surface after spraying with respect to the designed cross section can be grasped, it can be used for calculating the amount of concrete for the lining concrete.

[0016] According to the tunnel construction method of this embodiment, since three-dimensional point cloud data is acquired using a 3D scanner, it becomes possible to capture continuous data that could not be captured by measurement using a total station. In addition, it can be displayed on a display means such as a tablet in a state where an augmented reality model is overlaid on a photographed image of a face or a tunnel wall surface. Therefore, tunnel construction can be performed while visually confirming the construction status, displacement, etc. of the tunnel. Note that if the difference between the initial point cloud data and the first point cloud data is calculated, it becomes possible to visualize the spraying thickness.

[0017] As described above, the embodiments according to the present invention have been described. However, the present invention is not limited to the above-described embodiments, and each of the above-described components can be appropriately changed without departing from the spirit of the present invention. In the above embodiment, the case of tunneling by the blasting method has been described. However, the tunneling method is not limited, and for example, a mechanical tunneling method may be used. In the above embodiment, the initial point cloud data is measured. However, the initial measurement process may be performed as necessary. In the above embodiment, the case of driving rock bolts after spraying shotcrete has been described. However, the construction order of spraying shotcrete and rock bolts is not limited. For example, when spraying shotcrete is performed in two steps, rock bolts may be driven after the first spraying, and then the second spraying may be performed. In the above embodiment, the measurement (first measurement process, second measurement process) is performed after retreating the spraying machine from the face. However, the timing of measurement is not limited to this, and for example, it may be performed in a state where the spraying machine is near the face. Furthermore, if the measurement target section is approximately the daily advance distance, as shown in Figure 4(a), the first measurement process should be carried out at the end of work on the day the measurement target section is excavated, and the second measurement process should be carried out at the end of work on the section ahead of the measurement target section the following day (see Figure 4(b)). In other words, the first measurement process may be carried out after repeating the construction cycle, which consists of loading step to rock bolt step (or spraying step) as one cycle, multiple times. Note that the measurement length of the measurement target section is not limited, and the measurement length can be arbitrarily set within the range in which sufficient measurement accuracy can be ensured with the 3D scanner. In the above embodiment, the measurement target section is excavated in the first excavation process, and the section in front of the measurement target section is excavated in the second excavation process. However, the construction procedure is not limited to this. For example, the upper half may be excavated in the first excavation process, and the lower half in the second excavation process. Alternatively, in the second excavation process, the invert of the section (measurement target section) excavated in the first excavation process may be excavated. Furthermore, the second measurement process is not limited to after the second excavation process, but may also be performed when work resumes if work is interrupted after the first measurement process S4. The tunnel support structure will be determined according to the ground conditions, and accordingly, the steps included in the construction cycle can be modified as needed. [Explanation of symbols]

[0018] S1 First excavation process S2 Initial measurement process S3 Spraying Process S4 First measurement process S5 Second excavation process S6 Second measurement process S7 Process for creating difference point cloud data S8 Augmented Reality Display Process S9 Construction Confirmation Process

Claims

1. The first excavation process involves excavating the section to be measured, In the aforementioned measurement target section, a first measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain first point cloud data, In the aforementioned measurement target section, a second measurement step is performed in which point cloud data of the tunnel wall surface is measured again using a 3D scanner to obtain second point cloud data, A step to create difference point cloud data by calculating the difference between the first point cloud data and the second point cloud data, A tunnel construction method comprising an augmented reality display step of creating an augmented reality model using the aforementioned difference and displaying the augmented reality model on a display means, In the second measurement step, measurements are taken with a target placed on the tunnel wall. A tunnel construction method characterized in that, in the augmented reality display step, the target appearing in the augmented reality model is superimposed on the target installed on the tunnel wall, thereby displaying an image of the augmented reality model superimposed on the tunnel wall on the display means.

2. The first excavation process involves excavating the section to be measured, In the aforementioned measurement target section, a first measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain first point cloud data, A second excavation process is performed to excavate the section ahead of the aforementioned measurement target section, In the aforementioned measurement target section, a second measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain second point cloud data, A step to create difference point cloud data by calculating the difference between the first point cloud data and the second point cloud data, A tunnel construction method comprising an augmented reality display step of creating an augmented reality model using the aforementioned difference and displaying the augmented reality model on a display means, In the second measurement step, measurements are taken with a target placed on the tunnel wall. A tunnel construction method characterized in that, in the augmented reality display step, the target appearing in the augmented reality model is superimposed on the target installed on the tunnel wall, thereby displaying an image of the augmented reality model superimposed on the tunnel wall on the display means.

3. The first excavation process involves excavating the upper half of the section to be measured, In the aforementioned measurement target section, a first measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain first point cloud data, The second excavation process involves excavating the lower half of the aforementioned measurement target section, In the aforementioned measurement target section, a second measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain second point cloud data, A step to create difference point cloud data by calculating the difference between the first point cloud data and the second point cloud data, A tunnel construction method comprising an augmented reality display step of creating an augmented reality model using the aforementioned difference and displaying the augmented reality model on a display means, In the second measurement step, measurements are taken with a target placed on the tunnel wall. A tunnel construction method characterized in that, in the augmented reality display step, the target appearing in the augmented reality model is superimposed on the target installed on the tunnel wall, thereby displaying an image of the augmented reality model superimposed on the tunnel wall on the display means.

4. The first excavation process involves excavating the section to be measured, In the aforementioned measurement target section, a first measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain first point cloud data, A second excavation process is performed to excavate the invert of the measurement target section, In the aforementioned measurement target section, a second measurement step is performed in which point cloud data of the tunnel wall surface is measured using a 3D scanner to obtain second point cloud data, A step to create difference point cloud data by calculating the difference between the first point cloud data and the second point cloud data, A tunnel construction method comprising an augmented reality display step of creating an augmented reality model using the aforementioned difference and displaying the augmented reality model on a display means, In the second measurement step, measurements are taken with a target placed on the tunnel wall. A tunnel construction method characterized in that, in the augmented reality display step, the target appearing in the augmented reality model is superimposed on the target installed on the tunnel wall, thereby displaying an image of the augmented reality model superimposed on the tunnel wall on the display means.

5. The tunnel construction method according to any one of claims 1 to 4, characterized in that the display means is a portable terminal.

6. Prior to the first measurement step, there is a spraying step in which sprayed sprayed concrete onto the ground surface exposed by the first excavation step. The tunnel construction method according to any one of claims 1 to 4, characterized in that the difference is the amount of displacement of the ground.

7. Before the first measurement process, The initial measurement process involves measuring the exposed ground surface by the first excavation process using a 3D scanner to obtain initial point cloud data, The tunnel construction method according to any one of claims 1 to 4, further comprising a spraying step of spraying sprayed concrete onto the ground surface exposed by the first excavation step.

8. The tunnel construction method according to any one of claims 1 to 4, further comprising a completion confirmation step for calculating the difference between the first point cloud data and the design cross-section.

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