Work face observation system and work face observation method

Abstract

To propose a working-face observation system and a working-face observation method which measure safely and accurately the strike and dip of all bedding planes that are exposed at a tunnel working face.SOLUTION: This invention relates to a working-face observation system 100 comprising: a 3D scanner 2 that takes pictures of a tunnel excavation face F to generate point group data of the aforesaid pictures of the excavation face F; and a processing unit 1. The aforesaid processing unit 1 comprises: a generating part 11 that generates a 3D model on the basis of the aforesaid point group data that are obtained with the aforesaid 3D scanner 2; a measuring part 12 that measures the strike and dip of the virtual bedding planes exposed at the aforesaid 3D-model working face; and a display control part 13 that displays the aforesaid measuring part as a virtual measurement instrument on the aforesaid 3D model.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a face observation system and a face observation method used in mountain tunnel construction work.

Background Art

[0002] In recent years, technological development related to mountain tunnel construction work has been active, and inventions related to tunnel face observation are also known. For example, as a conventional face observation method, there is one that sketches the face or takes a photo of the face and evaluates the characteristics (e.g., unevenness, cracks) of the face from the sketch or photo. However, in the above method, it is impossible to approach the face from the safety aspect, so the unexcavated face of the face cannot be observed in detail. Also, in the case of a sketch, the recorded content may be insufficient due to time constraints during observation (loss of characteristic information). Also, in the case of a photo, there are circumstances such as it being not easy to determine whether it is a crack or a shadow. Therefore, there was a problem that the above method could not perform an appropriate evaluation. Also, there was a method of measuring the surface structure of the strata plane (discontinuity plane) from a position away from the face. For example, there was a method in which an operator moved to a position where the strata plane to be measured was visible vertically, overlapped it with a hard plate such as a sketch board to create a virtual same plane, and measured the strike and dip of the created plane. However, such a method had a problem that individual differences were likely to occur in the technique and the reproducibility of the measurement results was poor. Also, when the strata plane to be measured was distributed approximately parallel to the face plane, there was a problem that it had to be measured close to the face.

[0003] Also, as a conventional face observation method, there is the invention of Patent Document 1 that safely and accurately measures the strike and dip of the strata plane exposed at the face of a tunnel. The strike and dip measuring device of Patent Document 1 includes measuring means for measuring the distance to a measurement point on the strata plane exposed at the face of the tunnel and the angle with respect to a reference direction, and calculation means for calculating the strike, which is the direction of the intersection line between the strata plane and the horizontal plane, and the dip, which is the angle formed by the strike and the horizontal plane, based on the measurement results, which are the three-dimensional coordinate positions of at least three of the measurement points capable of forming a virtual plane.

Prior Art Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-148505 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the invention described in Patent Document 1 had the problem of being applicable in limited cases and lacking practicality. Specifically, it was limited to cases where the "surface" of the geological layer to be measured was exposed and the device for measuring that surface could be installed in a safe location away from the tunnel face. On the other hand, for example, when the surface of the geological layer to be measured is close to a vertical plane, it is rare for that surface to be exposed, and even when it is exposed, there is the problem that workers have to approach the tunnel face in order to measure that surface. From this perspective, the object of the present invention is to propose a tunnel face observation system and a tunnel face observation method for safely and accurately measuring the strike and dip of all geological layers exposed at the tunnel face. [Means for solving the problem]

[0006] The present invention, which solves the above problems, is a tunnel face observation system comprising a 3D scanner that photographs the excavation surface of a tunnel and generates point cloud data of the photographed excavation surface, and a computing device, wherein the computing device comprises a generation unit that generates a 3D model based on the point cloud data acquired from the 3D scanner, a measurement unit that measures the strike and dip of a virtual geological layer surface that appears at the tunnel face of the 3D model, and a display control unit that displays the measurement unit as a virtual measuring instrument on the 3D model. Furthermore, the present invention is a tunnel face observation method comprising the steps of: a 3D scanner photographing the excavation surface of a tunnel and generating point cloud data of the photographed excavation surface; a computing device generating a 3D model based on the point cloud data acquired from the 3D scanner; the computing device measuring the strike and dip of a virtual geological layer appearing at the tunnel face of the 3D model; and the computing device displaying a virtual measuring instrument for measuring the strike and dip of the virtual geological layer on the 3D model.

[0007] With this configuration, even if the 3D scanner is installed in a safe location away from the tunnel face, the point cloud data generated by the 3D scanner can retain information about the characteristics of the tunnel face, such as irregularities and cracks. Therefore, the geological layers that appear at the actual tunnel face can be reproduced as virtual geological layers on the 3D model. In other words, even if the geological layers are nearly parallel to the tunnel face or nearly vertical, the strike and dip can be measured relative to the virtual geological layer, allowing for safe and accurate measurement of the strike and dip of the geological layers exposed at the tunnel face. Furthermore, since the 3D scanner imaging can be completed in a short time after excavation and before shotcrete application, construction interruption time due to imaging of the excavation surface can be reduced. In addition, since the tunnel face observation using the 3D model can be performed remotely from the construction site, it is possible to achieve tunnel face observation without geographical or temporal limitations.

[0008] Furthermore, it is preferable that the display control unit displays, on the 3D model, a virtual line including the point of contact, and the measurement points when the strike and dip of the virtual geological layer are measured, when the virtual measuring instrument comes into contact with the virtual geological layer.

[0009] This allows users of the tunnel face observation system to assist in measuring strike and dip.

[0010] Furthermore, it is preferable that the computing device further includes an estimation unit that estimates a virtual key block using a first virtual stratum surface, a second virtual stratum surface, and a third virtual stratum surface, which are virtual stratum surfaces whose strike and dip have been measured.

[0011] This allows for the avoidance of collapse accidents by predicting the location of key blocks before construction begins.

[0012] Furthermore, it is preferable to further include a head-mounted display that displays the three-dimensional model and the virtual measuring device, and a controller that operates the virtual measuring device.

[0013] In this configuration, for example, if a head-mounted display and controller are connected to a user's PC equipped with a 3D model viewer, the user using the head-mounted display and controller can perform face observation under the same conditions as the tunnel construction site. Furthermore, when conducting a web conference with multiple people, including the user, sharing the screen of the head-mounted display enables remote meetings for face observation and on-site support from remote locations. [Effects of the Invention]

[0014] According to the present invention, the strike and dip of any geological surface exposed at the tunnel face can be measured safely and accurately. [Brief explanation of the drawing]

[0015] [Figure 1] This is a functional configuration diagram of the tunnel face observation system of this embodiment. [Figure 2] This is an example of a 3D model of the excavation surface. [Figure 3] This diagram illustrates the measurement of the strike of a virtual geological layer. (a) shows the position of a horizontal virtual clinometer in contact with the virtual geological layer, (b) is a cross-sectional view of the virtual geological layer when the virtual layer is cut by the horizontal plane containing the virtual clinometer, and (c) is a cross-sectional view showing the display control for the virtual geological layer. [Figure 4] This is an explanatory diagram for fine-tuning a virtual clinometer when measuring the strike of a virtual geological layer. [Figure 5] This is an explanatory diagram showing the result after the measurement of the strike of the virtual geological layer has been completed. [Figure 6]It is an explanatory diagram when measuring the inclination of a virtual formation plane. (a) is a diagram when a virtual clinometer perpendicular to the virtual formation plane is abutted against the virtual formation plane, (b) is a longitudinal sectional view when the virtual formation plane is cut by a vertical plane including the virtual clinometer, and (c) is a longitudinal sectional view showing display control with respect to the virtual formation plane. [Figure 7] It is an explanatory diagram of fine adjustment of a virtual clinometer when measuring the inclination of a virtual formation plane. [Figure 8] It is an explanatory diagram when the measurement of the inclination of the virtual formation plane is completed. [Figure 9] It is an explanatory diagram of the distribution of virtual formation planes whose strike and dip have been measured. [Figure 10] It is an explanatory diagram of the estimation of a key block. [Figure 11] It is an explanatory diagram of the determination of whether or not it is a key block. (a) is the case when it is determined that it is a key block, and (b) is the case when it is determined that it is not a key block. [Figure 12] It is a flowchart of the processing performed by the face observation method of this embodiment. [Embodiment for Carrying Out the Invention]

[0016] Hereinafter, embodiments for carrying out the present invention will be described in detail with appropriate reference to the drawings. Each figure only schematically shows to such an extent that the present invention can be sufficiently understood. Therefore, the present invention is not limited only to the illustrated examples. In each figure, common components and similar components are denoted by the same reference numerals, and redundant descriptions thereof are omitted. In this embodiment, the "excavation face" is the surface of the natural ground that appears by excavation, and includes the tunnel face (the face before shotcreting when shotcreting is performed) and the inner peripheral surface of the tunnel where the natural ground is exposed before the construction of the support after excavation. It is also referred to as the raw excavation face.

[0017] [Configuration] Figure 1 is a functional configuration diagram of the tunnel face observation system of this embodiment. The tunnel face observation system 100 is a system for observing the excavation surface F that appears after tunnel face excavation in the construction of a mountain tunnel in virtual reality (VR). As shown in Figure 1, the excavation surface F is an area not covered by concrete spraying (an area where the natural ground is visible), and consists of the excavation face surface f1 and the excavation inner circumferential surface f2. The excavation face surface f1 is the leading edge of the tunnel shaft. The excavation inner circumferential surface f2 is the inner circumferential surface portion of the tunnel that connects to the periphery of the excavation face surface f1, and is an area that is neither sprayed with concrete nor covered by support structures.

[0018] The tunnel face observation system 100 comprises a computing device 1, a 3D scanner 2, a work PC 3, an HMD 4 (Head Mounted Display), and a controller 5. The computing device 1, the 3D scanner 2, the work PC 3, the HMD 4, and the controller 5 are connected wirelessly or via wired communication over a network. For example, communication over a network can be achieved by implementing relay devices such as routers, mesh networks, and bridges (not shown). The 3D scanner 2 is a device that photographs (irradiates with a laser) the excavation surface F of the tunnel and generates point cloud data of the photographed excavation surface F. As shown in Figure 1, the 3D scanner 2 is positioned at a predetermined distance (e.g., 5m) from the excavation surface F to ensure safety from rockfalls and landslides on the excavation surface F, and can photograph the entire excavation surface F. The point cloud data is data that shows the point cloud plotted on the excavation surface F and has 3D coordinates in a predetermined 3D coordinate system (not shown). For example, several hundred million point clouds can be prepared for the excavation surface F, and each point can be arranged sufficiently densely. The 3D scanner 2 can acquire an image of the tunnel excavation surface F by photography and can also acquire color information of the tunnel excavation surface F.

[0019] The computing unit 1 is a computer that performs processing related to tunnel face observation. The work PC 3 is a computer used by the user. The HMD 4 is a display device worn on the user's head. The controller 5 is an input device that the user holds and operates. For example, the work PC 3 can have a viewer (not shown) installed to make the processing results from the computing unit 1 (e.g., point cloud data converted for VR) viewable in the VR space. The HMD 4 can display data in the VR space via the work PC 3. The controller 5 can control the data in the VR space according to the user's input. The user can perform tunnel face observation under conditions similar to those at a tunnel construction site.

[0020] The arithmetic unit 1 and the work PC 3 are equipped with hardware such as an input unit, an output unit, a control unit, and a memory unit. For example, if the control unit consists of a CPU (Central Processing Unit), the information processing performed by the computer including that control unit is realized by program execution processing by the CPU. Furthermore, the memory unit included in the computer stores various programs to realize the computer's functions according to the CPU's instructions. This enables collaboration between software and hardware. The programs can be provided by recording them on a recording medium or via a network.

[0021] (Details of arithmetic unit 1) As shown in Figure 1, the computing unit 1 comprises a generation unit 11, a measurement unit 12, a display control unit 13, and an estimation unit 14. The generation unit 11 generates a 3D model based on point cloud data acquired from the 3D scanner 2. The 3D model is point cloud data of the tunnel converted for VR and is placed in the VR space. Point cloud data is mainly prepared for the excavation surface F of the tunnel, but may also be prepared for areas other than the excavation surface F (e.g., the inner circumferential surface of the tunnel after support work is completed). The 3D model can be displayed by the HMD 4 and controlled by the controller 5. The excavation surface represented by the 3D model will be referred to as the "virtual excavation surface." The virtual excavation surface corresponds to the excavation surface F. Furthermore, the excavation face surface represented by the 3D model will be referred to as the "virtual excavation face surface," and the excavation inner circumferential surface represented by the 3D model will be referred to as the "virtual excavation inner circumferential surface." The virtual excavation face and virtual excavation inner surface correspond to the excavation face f1 and the excavation inner surface f2, respectively. When the 3D scanner 2 acquires color information of the tunnel excavation surface F, the generation unit 11 can color the 3D model using the color information.

[0022] The measurement unit 12 measures the strike and dip of a virtual geological layer that appears on the 3D model's excavation face (virtual excavation face). Here, the "virtual geological layer" is a geological layer obtained by observing the 3D model, and corresponds to the geological layer obtained by observing the excavation face F. The user can operate the controller 5 to operate the virtual clinometer (virtual measuring instrument) and measure the strike and dip of the virtual geological layer that appears on the virtual excavation face. The "virtual clinometer" is a clinometer displayed in a virtual space. A clinometer is a tool used in geological surveys to measure the strike and dip of geological layers. The display control unit 13 controls the display in the VR space. For example, the display control unit 13 can change the orientation and display magnification of the 3D model according to the operation of the controller 5. If the user holds the controllers with both hands and moves both controllers simultaneously in a circular motion toward the user, the display magnification will be increased, and if they move them in a circular motion in the opposite direction, the display magnification will be decreased. The display control unit 13 can also display the measurement unit 12 as a virtual clinometer in the 3D model. Furthermore, when the controller 5 is in a predetermined position in real space (e.g., within the field of view of the HMD4), the display control unit 13 can display the controller 5 as a virtual controller in the 3D model. When the estimation unit 14 sets a first virtual strata surface, a second virtual strata surface, and a third virtual strata surface as virtual strata surfaces for which strike and dip have been measured, it estimates a virtual key block using the first virtual strata surface, the second virtual strata surface, and the third virtual strata surface. A "virtual key block" is a key block in a virtual space. A key block is a rock mass demarcated by multiple strata surfaces.

[0023] (3D model) Figure 2 shows an example of a 3D model of the excavation surface. The 3D model in Figure 2 is displayed by an HMD4 and is viewable by a user wearing the HMD4. As shown in Figure 2, the 3D model represents a virtual excavation surface VF (virtual excavation face vf1 and virtual excavation inner surface vf2). The point cloud data that makes up the 3D model can accurately retain information about the characteristics of the excavation face (e.g., unevenness, cracks). In addition, the 3D model in Figure 2 can reproduce discontinuity surfaces of the strata that intersect with the actual excavation face (e.g., bedding surfaces, unconformities, intrusion surfaces, fold surfaces, fault surfaces (joint surfaces), etc.).

[0024] When a user presses a menu button (not shown) on the controller 5, the display control unit 13 displays a VR menu vm in the virtual space, as shown in Figure 2. The VR menu vm is a widget that summarizes the user's selectable operation items. The controller 5 may, but is not limited to, the above menu button, a confirmation button (not shown) for confirming an operation item, a cross button (not shown) for moving the target of the confirmation, and a back button (not shown) to return to the previous confirmation. The VR menu vm includes "Laser," "Sketch," "Distance Measurement," and "Clinometer." "Laser" is an operation item that causes the virtual controller V5 to emit a laser 5L into the virtual space. Laser 5L has the function of a pointer. "Sketch" is an operation item that activates a gadget (not shown) used to sketch the virtual drilling surface VF. "Distance Measurement" is an operation item that activates a gadget (not shown) used to measure the distance between any two points in the virtual space. "Clinometer" is an operation item that displays a virtual clinometer and the measurement results from the virtual clinometer in the virtual space. Note that the VR menu vm is not limited to "Laser," "Sketch," "Distance Measurement," and "Clinometer." For example, you could include "Display Magnification" and use a menu button to zoom in and out on the display in the VR space.

[0025] By the way, in order to safely proceed with tunnel excavation, it is important to understand how the discontinuities of the geological layers that appear at the tunnel face are distributed. Therefore, in this embodiment, the virtual geological layers that appear at the virtual excavation surface VF are identified in the 3D model. Specifically, the user viewing the 3D model focuses on the irregularities and cracks that appear at the virtual excavation face vf1. The irregularities and cracks on the excavation face f1 are highly likely to be shapes in which a part of the geological layer surface is exposed. In the 3D model of this embodiment, if the irregularities and cracks on the excavation face f1 are shapes in which a part of the geological layer surface is exposed, then it can be said that the irregularities and cracks that appear at the virtual excavation face vf1 are also shapes in which a part of the virtual geological layer surface is exposed.

[0026] (Selection of unevenness or cracks) As shown in Figure 2, the user operates the controller 5 to select "clinometer". The selection of "clinometer" can be done, for example, by moving the target to "clinometer" using the directional buttons and pressing the select button, or by selecting "laser" and aligning the displayed laser 5L with the "clinometer" before pressing the select button. The display control unit 13 displays the laser 5L irradiated onto the virtual excavation face vf1 based on the selection of "clinometer". Next, the user operates the controller 5 to align the laser 5L with the crack vfc on the virtual excavation face vf1 and then presses the select button. The display control unit 13 then displays a virtual clinometer VC (see Figure 3, etc.) at the location of the crack vfc. Note that the determination of the crack vfc can be, for example, by visual inspection or machine learning, but is not limited to these methods. Also, while this embodiment describes cracks, the same applies to surface irregularities.

[0027] (Measurement of strike and dip of virtual geological layers) The user operates the virtual clinometer VC with the controller 5 to measure the strike and dip of the virtual rock formation surface exposed by the crack vfc that has appeared on the virtual excavation face vf1. First, the case of measuring the strike of the virtual rock formation surface will be explained. Figure 3 is an explanatory diagram of the case of measuring the strike of the virtual rock formation surface, where (a) is a diagram when the horizontal virtual clinometer is brought into contact with the virtual rock formation surface, (b) is a cross-sectional view when the virtual rock formation surface is cut by the horizontal plane including the virtual clinometer, and (c) is a cross-sectional view showing the display control for the virtual rock formation surface. As shown in Figure 3(a), the virtual clinometer VC is rectangular. When measuring the strike of the virtual rock formation surface VL, the display control unit 13 displays the virtual clinometer VC horizontally with the instrument surface facing upward. One side of the virtual clinometer VC is brought into contact with the virtual rock formation surface VL. The dashed line in Figure 3(a) is a straight line that includes one side of the virtual clinometer VC that is in contact with the virtual geological plane VL, and can show the user an approximate height position of the virtual clinometer VC. As shown in Figure 3(b), among the point cloud data constituting the virtual geological plane VL, the partial point cloud data PG1 that intersects with the horizontal plane containing the virtual clinometer VC is identified. As shown in Figure 3(c), the display control unit 13 can display the virtual line vh connecting the identified partial point cloud data PG1 in a predetermined color on the 3D model. The display control unit 13 can also display the contact point VCa of the virtual clinometer VC that is in contact with the virtual line vh in a predetermined color on the 3D model. The display control unit 13 can display the cross-sectional views in Figures 3(b) and 3(c) in the virtual space.

[0028] Figure 4 is an explanatory diagram of the fine adjustment of the virtual clinometer when measuring the strike of a virtual geological layer. As shown in Figure 4, the user can operate the virtual clinometer VC with the controller 5 to fine-tune its attitude and position. This allows for optimization of the measurement of the strike of the virtual geological layer VL. As shown in Figure 4, the display control unit 13 can display windows W1 and W2 in the virtual space. Window W1 is a display frame for the virtual clinometer VC1 (equivalent to the virtual clinometer VC) and a cross-sectional view (equivalent to Figure 3(c)) including the virtual line vh. The virtual clinometer VC1 moves in conjunction with the fine adjustment of the virtual clinometer VC. Window W2 is a display frame for the strike and dip measurements taken by the virtual clinometer VC. When the virtual clinometer VC is fine-tuned, the strike measurement in window W2 changes (shown as "Strike: ○○○" in Figure 4). Also, since the dip measurement has not yet been taken, the dip measurement in window W2 is blank.

[0029] Figure 5 is an explanatory diagram showing the state after the measurement of the strike of the virtual geological layer is completed. After fine-tuning the virtual clinometer VC, when the user presses the confirm button on the controller 5, the adjustment of the virtual clinometer VC is completed and the strike is measured. At this time, the display control unit 13 displays the measurement point P in the virtual space. For example, the measurement point P can be the midpoint of one of the four sides of the adjusted virtual clinometer VC that is in contact with the virtual geological layer VL, but is not limited to this. The window W2 also displays the measured value of the determined strike. This completes the process related to the measurement of the strike of the virtual geological layer VL.

[0030] During the strike measurement, the user can operate the controller 5 to temporarily pause the movement of the virtual clinometer VC, change the user's viewpoint, or perform other actions in the virtual space. Furthermore, when positioning the virtual clinometer VC, the calculation unit 1 may control the virtual clinometer VC so that it does not pass through the point cloud data of the 3D model (see Figure 3(c)), or it may control it so that it does. Alternatively, the user may be able to select between controlling it to not pass through and controlling it to pass through.

[0031] Next, we will explain how to measure the inclination of a virtual geological layer. Figure 6 is an explanatory diagram for measuring the inclination of a virtual geological layer, where (a) shows the virtual clinometer perpendicular to the virtual geological layer in contact with the virtual geological layer, (b) is a longitudinal section when the virtual geological layer is cut by a vertical plane containing the virtual clinometer, and (c) is a longitudinal section showing the display control for the virtual geological layer. After the measurement of the strike of the virtual geological layer VL is completed, as shown in Figure 6(a), when measuring the inclination of the virtual geological layer VL, the display control unit 13 rotates the virtual clinometer VC by 90° around the measurement point P as the rotation center and displays it in a vertical position. One side of the virtual clinometer VC is in contact with the virtual geological layer VL. If the virtual geological layer VL is inclined (not vertical), the virtual clinometer VC will be in contact with the virtual geological layer VL in a diagonally vertical position (one side of the virtual clinometer VC is inclined with respect to the vertical line). The dashed line in Figure 6(a) is a straight line that includes one side of the virtual clinometer VC that is in contact with the virtual geological plane VL, and can show the user an approximate horizontal position of the virtual clinometer VC. As shown in Figure 6(b), among the point cloud data constituting the virtual geological plane VL, the partial point cloud data PG2 that intersects with the vertical plane containing the virtual clinometer VC is identified. As shown in Figure 6(c), the display control unit 13 can display the virtual line vv connecting the identified partial point cloud data PG2 in a predetermined color on the 3D model. The display control unit 13 can also display the contact point VCb of the virtual clinometer VC that is in contact with the virtual line vv in a predetermined color on the 3D model. The display control unit 13 can display the longitudinal sections in Figures 6(b) and 6(c) in the virtual space.

[0032] Figure 7 is an explanatory diagram of the fine adjustment of the virtual clinometer when measuring the inclination of a virtual geological layer. As shown in Figure 7, the user can operate the virtual clinometer VC with the controller 5 to fine-tune its attitude and position. This optimizes the measurement of the inclination of the virtual geological layer VL. As shown in Figure 7, the display control unit 13 can display windows W3 and W4 in the virtual space. Window W3 is a display frame for the virtual clinometer VC2 (equivalent to the virtual clinometer VC) and a longitudinal section diagram (equivalent to Figure 6(c)) including the virtual line vv. The virtual clinometer VC2 moves in conjunction with the fine adjustment of the virtual clinometer VC. Window W4 is a display frame for the strike and inclination measurements taken by the virtual clinometer VC. When the virtual clinometer VC is fine-tuned, the inclination measurement in window W4 changes (shown as "Inclination: ○○○" in Figure 7). Also, the strike measurement in window W4 shows the value that has already been measured.

[0033] Figure 8 is an explanatory diagram showing the state after the measurement of the dip of the virtual geological layer has been completed. After fine-tuning the virtual clinometer VC, when the user presses the confirm button on controller 5, the adjustment of the virtual clinometer VC is completed and the dip is measured. At this time, window W4 displays the measured value of the determined dip. This completes the process for measuring the dip of the virtual geological layer VL.

[0034] During the inclination measurement, the user can operate the controller 5 to temporarily pause the movement of the virtual clinometer VC, change the user's viewpoint, or perform other actions in the virtual space. Furthermore, when positioning the virtual clinometer VC, the calculation unit 1 may control whether the virtual clinometer VC is made transparent within the point cloud data of the 3D model (see Figure 6(c)) or transparent. The user may also be able to select between the non-transparent and transparent control.

[0035] The display control unit 13 can display measurement points P, measurement identifiers (No.), etc., on the virtual excavation face vf1 in the virtual space. If there are multiple geological layers on the virtual excavation face vf1, the measurement unit 12 can repeat the strike and dip measurements described above. The calculation unit 1 or the work PC 3 can output the strike and dip measurement results to a file in a predetermined format.

[0036] (Consideration of the cracks) By using a virtual geological layer surface VL whose strike and dip have been measured, it is possible to understand how the geological layers (discontinuities in the geological layers) appearing at the tunnel face are distributed. Figure 9 is an explanatory diagram of the distribution of virtual geological layers whose strike and dip have been measured. Figure 9 shows the entire tunnel represented by a 3D model. More specifically, the virtual excavation surface VF (virtual excavation face surface vf1 and virtual excavation inner surface vf2), the planned excavation space V1 corresponding to the ground ahead of the virtual excavation surface VF in the excavation direction, the space immediately after excavation V2 which is the space enclosed by the virtual excavation surface VF, the space with support structures (for reference), and the virtual geological layer surface VL (dashed line) are shown. The space combining the planned excavation space V1 and the space immediately after excavation V2 will be called the composite space VT. As shown in Figure 9, the display control unit 13 can extend and display the virtual geological layer surface VL to the ground ahead of the virtual excavation face surface vf1 according to the measured strike and dip. The extended virtual geological layer VL corresponds to the extended surface of the crack. As shown in Figure 9, the display control unit 13 can display the intersection line I (a thin dashed line) of the extended virtual geological layer VL and the point cloud data of the planned excavation space V1 in the virtual space. For illustrative purposes, the portion of the intersection line I that is on the virtual excavation face vf1 is hidden by the dashed line of the virtual geological layer VL.

[0037] (Key block estimation) When multiple cracks exist, multiple virtual rock layers can be identified for each crack, with their strike and dip measured. Furthermore, each of these identified virtual rock layers can be extended. By combining multiple extended virtual rock layers, key blocks can be evaluated, and the possibility of collapse during excavation work can be assessed. The evaluation of key blocks can be achieved, for example, by having a skilled engineer check the results of an automated identification process using existing software (e.g., Key Block Analysis System, Tsukuba Software Engineering Co., Ltd.) based on Shee's theorem (R.E. Goodman, G.H. Shee, translated by Ryunosuke Yoshinaka and Yuzo Onishi, "Block Theory and its Application to Rock Mechanics," Civil Engineering Co., Ltd.). This can be applied to the 3D model in this embodiment.

[0038] Figure 10 is an explanatory diagram of key block estimation. If at least three discontinuities in geological strata (three in Figure 10) appear on the virtual excavation surface VF of the tunnel represented in the 3D model, the display control unit 13 can display three virtual geological strata surfaces VL1 (single dashed line), VL2 (double dashed line), and VL3 (dotted line) on the 3D model for each of the three discontinuities in geological strata. The estimation unit 14 finds the intersection point S of the virtual geological strata surfaces VL1, VL2, and VL3. Specifically, it calculates the equations of the planes of the virtual geological strata surfaces VL1, VL2, and VL3 according to the 3D coordinate system shown in Figure 10, and calculates the coordinates of the intersection point S (details of the calculation are omitted). Next, the estimation unit 14 determines the intersection line I12 of the virtual strata VL1 and VL2, the intersection line I23 of the virtual strata VL2 and VL3, and the intersection line I31 of the virtual strata VL3 and VL1 (details of the calculation are omitted).

[0039] Next, the estimation unit 14 determines whether all of the intersection lines I12, I23, and I31 pass through the interior of the combined space VT that combines the planned excavation space V1 and the immediately excavated space V2. As shown in FIG. 10, the tunnel excavation progress direction is the -Z direction. Also, the virtual excavation face vf1 is regarded as the upper semi-circle (Y≧0) with a radius R. Further, an auxiliary surface cf is prepared as an upper semi-circle separated from the upper semi-circle of the virtual excavation face vf1 by a distance L in the +Z direction. The arc of the auxiliary surface cf substantially coincides with the peripheral edge of the virtual excavation inner surface vf2 (the peripheral edge that does not connect to the virtual excavation face vf1). Also, the center of the circle of the auxiliary surface cf is the origin of the three-dimensional coordinate system prepared in the virtual space. The planned excavation space V1 extends in the -Z direction from the virtual excavation face vf1 and has an upper semi-cylindrical shape with a radius R centered on the Z axis. Also, the immediately excavated space V2 has an upper semi-cylindrical shape with a radius R sandwiched between the virtual excavation face vf1 and the auxiliary surface cf. The estimation unit 14 can determine that all of the intersection lines I12, I23, and I31 pass through the interior of the combined space VT when the point (x, y, z) on the intersection lines I12, I23, and I31 simultaneously satisfies the following inequalities [1] to [3]: [1] |x|≦R, [2] 0<y<(R^2 - x^2)^0.5, [3] z≦0.

[0040] FIG. 11 is an explanatory diagram for determining whether it is a key block. (a) shows the case where it is determined that it is a key block, and (b) shows the case where it is determined that it is not a key block. In FIG. 11(a), all of the intersection lines I12, I23, and I31 pass through the interior of the combined space VT. Therefore, the estimation unit 14 can estimate the ground surrounded by the intersection lines I12, I23, I31 and the cylindrical surface of the combined space VT as the virtual key block VK, and can evaluate that there is a high possibility of a collapse disaster when the excavation work proceeds. On the other hand, in FIG. 11(b), none of the intersection lines I12, I23, and I31 pass through the interior of the combined space VT. In such a case, since there is no ground surrounded by the intersection lines I12, I23, I31 and the cylindrical surface of the combined space VT, the estimation unit 14 can estimate that there is no virtual key block, and can evaluate that the possibility of a collapse disaster is low when the excavation work proceeds.

[0041] [Web Conference] By providing multiple PCs that are connected to at least one of the computing device 1 and the work PC 3 in a way that allows communication, a web conference regarding the 3D model of the tunnel can be realized between participants using each PC and users using the HMD4 and controller 5. Furthermore, when conducting a web conference with multiple people, including users, sharing the HMD4 screen enables remote meetings for tunnel face observation and on-site support from remote locations.

[0042] [process] The process performed in the tunnel face observation method of this embodiment will now be described. Figure 12 is a flowchart of the process performed in the tunnel face observation method of this embodiment. The process in Figure 12 starts when the 3D scanner 2 photographs the excavated surface of the tunnel. First, the computing device 1 acquires point cloud data of the tunnel from the 3D scanner 2 (step S1). Next, the generation unit 11 of the computing device 1 generates a 3D model based on the point cloud data acquired from the 3D scanner 2 (step S2). The HMD4 can display the 3D model via the work PC 3. Next, the computing device 1 selects irregularities or cracks that appear on the virtual excavated face surface vf1 of the 3D model by irradiating it with a laser 5L from the virtual controller V5 according to the operation from the user controller 5 (step S3). Next, the display control unit 13 of the computing device 1 displays a virtual clinometer VC at the location of the selected irregularities or cracks (step S4). Next, the measurement unit 12 of the calculation unit 1 measures the strike and dip of the virtual rock formation surface exposed as a selected irregularity or crack, in accordance with the operation of the virtual clinometer VC via the user's controller 5 (step S5). Subsequently, if there are three or more virtual rock formation surfaces for which the strike and dip have been measured, the estimation unit 14 of the calculation unit 1 estimates a virtual key block using the three virtual rock formation surfaces for which the strike and dip have been measured (step S6), and the process in Figure 12 is completed. Specifically, the estimation unit 14 determines whether or not there is a ground formation surrounded by the three virtual rock formation surfaces and the cylindrical surface of the composite space VT (Figure 10 or Figure 11), and outputs the determination result (whether or not there is a possibility of collapse disaster if excavation work is carried out). The process in Figure 12 can be repeatedly performed for all combinations of three virtual rock formation surfaces arbitrarily selected from the virtual rock formation surfaces for which the strike and dip have been measured, if there are four or more virtual rock formation surfaces for which the strike and dip have been measured.

[0043] According to this embodiment, even if the 3D scanner 2 is installed in a safe location away from the tunnel face, the point cloud data generated by the 3D scanner 2 can retain information about the characteristics of the tunnel face, such as irregularities and cracks. Therefore, the geological layers that appear at the actual tunnel face can be reproduced as virtual geological layers on the 3D model. In other words, even if the geological layers are nearly parallel to the tunnel face or nearly vertical, the strike and dip can be measured relative to the virtual geological layers, allowing for safe and accurate measurement of the strike and dip of the geological layers exposed at the tunnel face. Furthermore, since the 3D scanner photography can be completed in a short time between excavation and shotcrete application, construction interruption time due to photography of the excavated surface can be reduced. In addition, since the tunnel face observation using the 3D model can be performed remotely from the construction site, tunnel face observation can be realized without geographical or temporal limitations.

[0044] [Differentiation] (a): The excavation surface F appears with each cycle of the excavation work at the tunnel face. Therefore, the 3D scanner 2 captures the excavation surface F with each cycle, and the generation unit 11 can generate a virtual excavation surface VF for each cycle. Thus, the computing unit 1 can generate a 3D model of the tunnel consisting only of the excavation surface (without support structures) by stitching together the virtual excavation surface VF for each cycle. Users using the HMD4 and controller 5, and those participating in the web conference, can observe the 3D model of the tunnel consisting only of the excavation surface to observe in detail, for example, the strata appearing across the entire tunnel face and inner surface, without time constraints. Furthermore, a virtual strata surface set in the virtual excavation surface VF corresponding to a certain cycle may be displayed in the virtual excavation surface VF corresponding to subsequent cycles. In this way, it becomes possible to verify the validity of the virtual strata surfaces set in past cycles. (b): In this embodiment, the case in which a crack (or irregularity) appearing on the virtual excavation face vf1 of the virtual excavation surface VF is selected has been described. However, the present invention can also be applied to the case in which a crack (or irregularity) appearing on the virtual excavation inner surface vf2 of the virtual excavation surface VF is selected. Furthermore, the estimation unit 14 can estimate a virtual key block using a total of three virtual geological surfaces, including one virtual geological surface exposed as an irregularity or crack appearing on the virtual excavation face vf1, and one virtual geological surface exposed as an irregularity or crack appearing on the virtual excavation inner surface vf2.

[0045] (j): It is also possible to realize technologies that appropriately combine the various technologies described in this embodiment. (k): The software described in this embodiment can be implemented as hardware, and the hardware can be implemented as software. (l) In addition, hardware, software, flowcharts, etc. can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0046] 100-Meter Observation System 1 Computing device 11 Generation part 12 Measuring part 13 Display Control Unit 14 Estimation part 2D scanners 3 Work PC 4 HMD 5 Controllers V5 Virtual Controller F Excavation surface f1 Excavation face f2 Inner surface of excavation VF Virtual drilling surface vf1 Virtual excavation face vf2 Virtual excavation inner surface VFC crack VC, VC1, VC2 Virtual clinometer (virtual measuring instrument) VCa, VCb contact points VL, VL1, VL2, VL3 Virtual strata PG1, PG2 Partial Point Cloud Data vh,vv virtual line W1, W2, W3, W4 windows P measurement point S intersection I,I12,I23,I31 intersection line V1 Planned drilling space V2 Space immediately after excavation VT synthetic space cf auxiliary surface VK Virtual Key Block

Claims

1. The system comprises a 3D scanner that photographs the excavation surface of a tunnel and generates point cloud data of the photographed excavation surface, and a computing device. The aforementioned computing device is A generation unit that generates a three-dimensional model based on the point cloud data acquired from the three-dimensional scanner, A measuring unit for measuring the strike and dip of a virtual geological layer appearing at the face of the three-dimensional model, A tunnel face observation system comprising a display control unit that displays the aforementioned measuring unit as a virtual measuring instrument on the three-dimensional model.

2. The display control unit, when the virtual measuring instrument comes into contact with the virtual geological layer surface, The tunnel face observation system according to claim 1, which displays a virtual line including the contact point and measurement points when the strike and dip of the virtual geological layer surface are measured on the three-dimensional model.

3. The face observation system according to claim 1, wherein the calculation device further comprises an estimation unit that estimates a virtual key block using a first virtual geological surface, a second virtual geological surface, and a third virtual geological surface, which are virtual geological surfaces whose strike and dip have been measured.

4. A head-mounted display that displays the three-dimensional model and the virtual measuring instrument, The face observation system according to claim 1, further comprising a controller for operating the virtual measuring device.

5. The three-dimensional scanner takes a photograph of the tunnel excavation surface and generates point cloud data of the photographed excavation surface. The computing device generates a three-dimensional model based on the point cloud data acquired from the three-dimensional scanner, The calculation device performs the steps of measuring the strike and dip of the virtual strata surface that appears at the face of the three-dimensional model, A method for observing a tunnel face, comprising the step of causing the calculation device to display virtual measuring instruments for measuring the strike and dip of the virtual geological layer on the three-dimensional model.

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