JP7623232B2 - Tunnel construction management method - Google Patents

Description

The present invention relates to a tunnel construction management method for selecting an appropriate construction method for tunnel excavation.

When constructing a tunnel, surveying is carried out at each designated excavation stage to ensure that the excavation is being carried out according to plan. At tunnel construction sites, where construction is being carried out on constantly changing ground, it is important to manage the construction by collecting on-site information as quickly as possible through accurate surveying and ground observation, and then taking appropriate action.

For example, in the New Austrian Tunneling Method (NATM) for excavating mountain tunnels, the ground is managed by measurements known as measurement work A to ensure the stability of the ground around the tunnel and to carry out appropriate construction according to the ground's properties. In measurement work A, for example, the ground is measured over time and the deformation behavior of the tunnel is managed. Measurement work A confirms and evaluates the characteristics of the tunnel's deformation behavior and determines the next construction method to be used. The cross sections to be measured for measurement work A are set up at intervals of 10 to 30 m in the direction of tunnel excavation according to the ground properties.

As the tunnel is excavated and the face is formed, the initial values of the measurement points are measured using a 3D surveying device capable of automatic 3D measurements, and then the measurement points are automatically measured every 12 to 24 hours, and the incremental displacement at the measurement points is automatically recorded. Basically, measurements are taken at five measurement points per cross section.

JP 2008-298432 A JP 2014-2027 A JP 2020-133118 A JP 2020-172784 A

As mentioned above, the cross sections that are the subject of measurement work A are set at predetermined intervals in accordance with the characteristics of the ground. Measurements are then taken over time at measurement points at predetermined locations, and the displacement of the coordinates at these measurement points is quantified and managed as the tunnel deformation behavior due to tunnel excavation.

Low-strength, discontinuous plastic flow ground can cause large deformation during tunnel construction. When constructing a tunnel in such ground, even if surveying is carried out to grasp the deformation of the ground based on standard measurement method A, there is a problem that it is difficult to accurately grasp and evaluate the displacement behavior of the tunnel. Therefore, with standard measurement method A, it is not possible to determine in real time which excavation method or tunnel support structure is optimal for the ground, and there is a risk that construction will have to be re-done.

Furthermore, increasing the number of measurement points and cross sections to be measured in response to measurement work A requires a great deal of time, effort, and cost for the measurement work, so there are limitations to predicting and evaluating the displacement behavior at the excavation surface. According to the inventions described in Patent Documents 1 to 4, it is described that the tunnel excavation surface is measured and the measurement results are displayed in real time, but there has been no proposal yet to select a construction method that corresponds to the tunnel deformation behavior.

The present invention aims to provide a tunnel construction management method that can select a construction method in real time that corresponds to the excavated ground properties and the tunnel deformation behavior in the ground.

The present invention is a tunnel construction management method comprising the steps of: measuring the three-dimensional coordinates of a plurality of measurement points on the construction surface after excavation of a tunnel at least twice at different times; calculating the deformation behavior of the tunnel based on the difference in data obtained in the measurements; superimposing and displaying a display image corresponding to a threshold value set for the deformation behavior on a three-dimensional image of the tunnel; and displaying a construction method corresponding to the threshold value for the deformation behavior.

According to the present invention, by performing three-dimensional surveying of the construction surface after tunnel excavation over time, it is possible to grasp the deformation behavior of the tunnel in real time and to select a construction method according to the deformation behavior.

The construction surface of the present invention may include an excavation surface of the natural ground and a surface of concrete applied to the excavation surface, and the process of calculating the deformation behavior of the tunnel may include a process of measuring a plurality of three-dimensional coordinates on the construction surface corresponding to a virtual unit plane set based on a predetermined circumferential length and a predetermined extension length of the tunnel, a process of calculating an average value of the plurality of three-dimensional coordinates, and a process of calculating the difference in the average value over time.

According to the present invention, by using surveying equipment such as a laser scanner to calculate deformations in real time on the excavated surface of a tunnel and on the surface of concrete applied to the excavated surface, changes in the tunnel can be grasped at an early stage.

In addition, the threshold value of the present invention may be set in stages according to the magnitude of the difference.

According to the present invention, by setting a construction method according to a threshold value, it is possible to display an appropriate construction method according to the real-time deformation of the tunnel.

The present invention may also include selecting the construction method displayed according to the state of the deformation behavior, and implementing the construction method on the tunnel.

According to the present invention, the manager can select the displayed construction method and carry out construction work on the tunnel, allowing construction management to quickly respond to changes in the tunnel.

According to the present invention, a construction method that corresponds to the excavated ground properties and the tunnel deformation behavior in the ground can be selected in real time.

FIG. 1 is a diagram showing the configuration of a completed form survey management system used in a tunnel construction management method. FIG. 1 is a diagram showing an overview of a surveying method inside a tunnel. FIG. 2 is a block diagram showing a configuration of a management device. 4 is a cross-sectional view taken along the tunnel axis direction, showing the configuration of the tunnel. FIG. FIG. 2 is a radial cross-sectional view showing the configuration of the tunnel. FIG. 1 is a diagram showing a method for surveying a tunnel. FIG. 1 is a diagram showing a method for time-series surveying of a tunnel. FIG. 1 illustrates a method for calculating the thickness of concrete. This is a diagram explaining the early closure of a tunnel and subsequent surveying. 1 is a flowchart showing a process flow of a tunnel construction management method.

Below, an embodiment of a tunnel construction management method according to the present invention will be described with reference to the drawings. The tunnel construction management method uses a management system that can measure the shape inside a tunnel in three dimensions. First, the management system will be described.

As shown in FIG. 1, the completed form construction management system 1 used in the tunnel construction management method includes a laser scanner 10 (three-dimensional scanner) that measures the three-dimensional shape inside the tunnel, a total station 30 that measures the three-dimensional coordinates inside the tunnel, and a management device 20 that manages the construction of the tunnel based on the measurement data from the laser scanner 10 and the total station 30.

The laser scanner 10, for example, includes a laser sensor 11 that irradiates laser light and receives a portion of the reflected light, and a main body 12 that rotatably supports the laser sensor 11 and drives it to rotate. The laser sensor 11 includes a laser light emitter (not shown) and a light receiver (not shown). The laser sensor 11, for example, irradiates a target object with laser light in a planar manner while rotating in the vertical and horizontal directions, measures the time it takes to receive a portion of the reflected light from the target object, and generates point cloud data.

The laser sensor 11 is supported by the main body 12 so as to be rotatable around the y-axis (tilt direction) and is driven to rotate. This allows the laser sensor 11 to scan the target in the vertical direction. The main body 12 is placed on a tripod S. The main body 12 is driven to rotate around the z-axis relative to the tripod S. This allows the laser sensor 11 to be supported so as to be rotatable around the z-axis (horizontal direction) and is driven to rotate.

In this way, the laser scanner 10 can scan a specified area of the object in three dimensions and obtain data on the surface shape of the object in the specified area. The total station 30 measures the three-dimensional survey coordinates of multiple side points in the tunnel T. The total station 30 outputs the multiple survey coordinate data to the laser scanner 10. The laser scanner 10 measures the three-dimensional shape of the excavation surface based on the measurement points based on the survey coordinates, based on the multiple survey coordinate data.

As shown in FIG. 2, the laser scanner 10 surveys the excavation surface of the tunnel and the surface of the face mirror when excavation is completed, for example, and obtains data on the surface shape. The laser scanner 10 outputs the measured point cloud data to the management device 20. The laser scanner 10 surveys the concrete sprayed surface after concrete is sprayed onto the excavation surface for the first time, for example, and obtains data on the surface shape. The laser scanner 10 also surveys the surface shape of the concrete sprayed surface after shoring is erected and concrete is sprayed for the second time to cover the surface of the shoring, for example, and obtains data on the surface shape.

The management device 20 is realized by a terminal device such as a personal computer (PC), a tablet terminal device, a smartphone, etc. The management device 20 is connected to the laser sensor 11 in a wired or wireless manner so as to be able to communicate with the laser sensor 11.

As shown in FIG. 3, the management device 20 includes a calculation unit 21 that calculates the three-dimensional shape of the object based on the data acquired from the laser sensor 11, a display unit 22 that displays various information generated based on the calculation results of the calculation unit 21, and a memory unit 23 that stores various data.

The calculation unit 21 is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The program may be stored in advance in a storage device such as an HDD (Hard Disk Drive) or flash memory, or may be stored in a removable storage medium such as a DVD or CD-ROM, and installed by inserting the storage medium into a drive device. The computer program may also be distributed to a computer via a communication line, and the computer that receives the distribution may execute the program.

The calculation unit 21 acquires measurement data obtained by three-dimensionally scanning the object by the laser sensor 11. The calculation unit 21 generates image data of the three-dimensional shape of the object based on the acquired data. A detailed explanation of the measurement principle by the calculation unit 21 is described in Patent Document 1. For example, in addition to generating image data and numerical data of the three-dimensional shape of the object, the calculation unit 21 generates management information that compares the design data and measurement data stored in the memory unit 23. The calculation unit 21 controls the display unit 22 to display the display contents of the generated image data, etc.

The display unit 22 displays an image of the three-dimensional shape inside the tunnel generated by the calculation unit 21 and management information. The display unit 22 is realized by a display device such as a liquid crystal display, an organic electroluminescence display, or an LED display.

The memory unit 23 records the survey data measured by the laser sensor 11, the image data generated by the calculation unit, the design data including the design details of the tunnel, etc. The memory unit 23 is a storage device such as a HDD, flash memory, RAM (Random Access Memory), or ROM (Read Only Memory).

Next, a tunnel construction management method for managing the excavation of a tunnel will be described. The tunnel construction management method is applied, for example, to the construction of mountain tunnels. In the construction of mountain tunnels, the ground is blasted and excavated using machinery or human power, and then supports are constructed to support the ground, and the ground is excavated while maintaining the internal space to build the tunnel.

According to this construction method, construction is carried out on the assumption that the ground near the face will be self-sustaining from the time of excavation to form the face until construction of the support is completed. Therefore, construction management for mountain tunnels requires careful consideration in advance and the establishment of construction procedures after excavation to prevent the collapse of the ground.

As shown in FIG. 4, the tunnel T to be constructed has an excavated face T1 at its front end. Behind the excavation direction of the face T1, concrete is sprayed onto the excavated face to form a layer of sprayed concrete T2.

As shown in FIG. 5, in tunnel T, a layer of sprayed concrete T2 is formed on the surface of excavation surface K. The layer of sprayed concrete T2 includes, for example, a first sprayed concrete sprayed onto the ground, a support structure assembled on the surface of the first sprayed concrete, and a second sprayed concrete sprayed onto the surface of the support structure. Next, a layer of lining concrete T3 is formed to cover the surface of the layer of sprayed concrete T2. In tunnel excavation in low-strength ground, a layer of invert shotcrete T4 is formed on the surface of excavation surface K at the bottom of tunnel T, and then a layer of invert concrete T5 is formed to cover the surface of the layer of invert shotcrete T4. In addition, in tunnel T, multiple rock bolts B are driven radially into the ground.

At the top of tunnel T, multiple steel pipe forepillings P are cast at a specified angle upward from the surface of the ground toward the tunnel axis using an auxiliary construction method. The steel pipe forepillings P are arranged along the outer periphery of the tunnel. Silica resin or the like is pressure-injected into the steel pipe forepillings P to ensure the independence of the excavated surface up to the support structure.

As shown in Figures 6 and 7, in tunnel T, the surface shape of the sprayed concrete T2 is three-dimensionally constructed by the construction management system 1 at the face of the excavation surface that appears in the construction cycle. Based on the difference between the survey data of the surface shape of the current sprayed concrete T2 and the survey data of the surface shape of the past sprayed concrete T2, the management device 20 calculates (1) the initial deformation speed, (2) the tunnel deformation at the sprayed surface finished form survey position, and (3) the current excavation incremental deformation, and (4) visualizes the tunnel excavation impact of the early closing incremental deformation and the tunnel deformation behavior characteristics by displaying a color-coded display based on a threshold value on the display unit, and selects the next construction corresponding to the tunnel deformation behavior. Below, a specific tunnel construction management method based on the construction management system 1 will be described.

The construction management system 1 performs three-dimensional surveying of the tunnel face T1 for each construction cycle of the tunnel T. The laser scanner 10 is located at the center of the tunnel and one excavation length behind the tunnel face T1. The total station 30 is located behind the laser scanner 10. The total station 30 measures the three-dimensional surveying coordinates of the measurement points based on targets set at multiple measurement points. The targets G measured by the total station 30 are set at three points within a maximum range of 7 m from the laser scanner 10 and are automatically recognized during three-dimensional surveying by the laser scanner 10. The total station 30 transmits the three-dimensional surveying coordinates of the measurement points to the laser scanner 10.

When tunnel T is a two-lane road, laser scanner 10 performs three-dimensional surveying of the tunnel face T1 and an area 20 m behind it (2D: D is the excavation width). Laser scanner 10 performs surveying at a distance of 10 m with measurement points spaced 12.5 mm apart, and performs three-dimensional as-built surveying of tunnel face T1 with measurement points spaced approximately 7 mm apart on the side of the tunnel around laser scanner 10.

The management device 20 calculates the following values as deformation behavior of the tunnel T based on the completed form survey using the laser scanner 10: (1) initial deformation speed, (2) tunnel deformation at the sprayed surface completed form survey position, (3) current excavation incremental deformation, and (4) early closure incremental displacement. For example, the management device 20 calculates the difference between the point cloud data of the measurement point surveyed this time and the point cloud data of the measurement point surveyed previously based on the concrete thickness calculation method described below. The management device 20 generates a display image based on the calculation results, and displays the display image in a color-coded manner based on a threshold on the display unit 22. The concrete thickness is calculated based on the following method.

As shown in Figure 8, a rectangular virtual unit plane of a specified length (10 cm) in the circumferential direction by a specified length (10 cm) in the extension direction is defined in the construction area of the tunnel. The virtual unit plane is set on the sprayed surface in the design. Three-dimensional surveying is performed using a laser scanner with the virtual unit plane as a reference. Surveying is performed at least twice, once on the excavated surface and once on the surface after the sprayed concrete has been applied. In addition, three-dimensional surveying is performed more than twice at different times over time on the construction surface after excavation and on the same position on the concrete surface, as described below.

The surface of the sprayed concrete has irregularities of about 5 to 10 mm. In contrast, the ground on the excavated surface has similar irregularities, although this differs depending on the geology. A laser scanner is used to survey the excavated surface before the sprayed concrete is applied and the surface of the concrete after application in a virtual unit plane, at grid points spaced 5 to 12.5 mm apart. The surveying produces point cloud data that is a collection of the three-dimensional coordinates of the surface of the concrete before and after the sprayed concrete is applied in the virtual unit plane. The thickness of the concrete is calculated based on the point cloud data of the excavated surface and the concrete surface obtained by the surveying.

Since the thickness of the sprayed concrete is small compared to the distance from the laser scanner 10 to the survey surface, it is calculated by averaging the point cloud data in the virtual unit plane. By calculating the difference between the average value of the point cloud data in the virtual unit plane and the average value of the point cloud data on the surface of the sprayed concrete, an approximation of the thickness of the concrete at the centre point of the virtual unit plane is obtained. The management device 20 generates an image in which the point cloud data of the concrete surface obtained by the survey is expressed in three-dimensional coordinates, and displays it on the display unit 22. At this time, the management device 20 displays the point cloud data of the concrete surface by changing the colour tone according to the thickness threshold value.

The above method describes the thickness of the sprayed concrete, but the thickness of the lining concrete and the invert concrete can also be calculated using a similar method and displayed on the display unit 22 by changing the color tone.

Next, a method for calculating the initial deformation speed of tunnel T will be described. The management device 20 uses point cloud data P(i-1) of the concrete sprayed surface at measurement point (i-1) measured last time in the excavation cycle and point cloud data P(i) at measurement point (i) measured this time at the same position as last time to calculate the average value of the distance from the center of the virtual unit plane, and calculates the surface position in the previous survey and the surface position in the current survey.

The management device 20 calculates the initial deformation speed based on the difference between the surface position in the previous survey and the surface position in the current survey. The management device 20 generates an image in which the calculated initial deformation speed is plotted on the point cloud data of the concrete surface, and displays it on the display unit 22. For example, the management device 20 displays the initial deformation speed by changing the color tone according to a preset threshold value. The management device 20 displays on the display unit 22 the response to the next construction set in correspondence with the threshold value as shown in Table 1.

Next, a method for calculating the tunnel deformation at the sprayed surface completed survey position will be described. The management device 20 calculates the average value of the distances from the center of the virtual unit plane using point cloud data P(i-1, i-2, i-3, . . .) acquired at the sprayed surface of the concrete at the measurement points (i-1, i-2, i-3, . . .) surveyed up to the previous time in the excavation cycle and point cloud data P(i) acquired at the same position (i-1, i-2, i-3, . . .) surveyed up to the previous time. The management device 20 calculates the tunnel deformation at the sprayed surface completed survey position based on the difference between the respective average values. For example, the management device 20 changes the color tone of the tunnel deformation at the sprayed surface completed survey position according to a preset threshold value and displays it. The management device 20 displays the response of the next construction set corresponding to the threshold value on the display unit 22 as shown in Table 2.

Next, a method for calculating the current tunnel excavation incremental deformation will be described. The management device 20 calculates the average value of the distance from the center of the virtual unit plane using the point cloud data P(i-1) acquired at the previously surveyed measurement point (i-1) and the point cloud data P(i) rearward from the same position as the previous time of the currently surveyed measurement point (i). The management device 20 calculates the current excavation incremental deformation based on the difference between the average values of the respective distances. The management device 20 displays the current excavation incremental deformation by changing the color tone according to a preset threshold value. The management device 20 displays the construction method set corresponding to the threshold value on the display unit 22 as shown in Table 3.

管理装置２０は、閾値に対応して設定された工法を表示部２２に表示する。 Next, a method for calculating the early closure incremental deformation will be described. The management device 20 calculates the average value of the distance from the center of the virtual unit plane using point cloud data P(2) of the measurement point (aa) in the entire cross section of the early closed concrete sprayed surface and point cloud data P(1) of the measurement point in the entire cross section before early closure. The management device 20 calculates the early closure incremental deformation based on the difference between the average values of the respective distances. The management device 20 displays the early closure incremental deformation by changing the color tone according to a preset threshold value as shown in Table 4.

The management device 20 displays on the display unit 22 the construction method set in accordance with the threshold value.

As shown in Fig. 9, in the subsequent tunnel excavation construction, the incremental deformation due to tunnel excavation is confirmed and evaluated as the current excavation incremental deformation described above, regardless of whether early closure occurs or not (Table 4).

Next, the processing flow of the tunnel construction management method will be explained. The construction surface that is the subject of 3D surveying by the laser scanner 10 includes the excavation surface of the natural ground and the surface of the concrete applied to the excavation surface. The concrete surface includes the surface of concrete applied to the excavation surface, such as the surface of sprayed concrete, the surface of lining concrete, and the surface of invert concrete.

Figure 10 shows the flow of each process of the tunnel construction management method. Using a laser scanner 10, the three-dimensional coordinates of multiple measurement points on the construction surface after excavation of the tunnel are measured at least twice at different times (step S10). In this measurement, the management device 20 calculates the average value of multiple three-dimensional coordinates measured on the construction surface corresponding to a virtual unit plane set based on a predetermined circumferential length and a predetermined extension length of the tunnel T, and further calculates the difference in the average value over time to calculate the concrete thickness and the amount of movement of the concrete surface over time. In other words, the management device 20 calculates the deformation behavior of the tunnel T based on the difference in the data acquired in the measurement (step S12).

Next, the management device 20 generates a three-dimensional image of the tunnel, and overlays a display image using colors corresponding to thresholds that are set in stages according to the magnitude of the difference in data on the three-dimensional image (step S14). The administrator can grasp the deformation behavior of the tunnel T in real time based on the image displayed on the display unit 22. Next, the management device 20 displays a construction method corresponding to the threshold value of the deformation behavior (step S16). The administrator selects the construction method displayed on the display unit 22 according to the state of the deformation behavior, and constructs the tunnel T using the selected construction method (step S18).

By selecting a construction method displayed on the display unit 22, the manager can quickly carry out construction using an appropriate construction method that corresponds to the real-time deformation behavior of the tunnel.
The above steps are performed for each predetermined tunnel excavation cycle.

As described above, according to the tunnel construction management method, the management device 20 can visualize and display in real time evaluation items related to ground deformation based on three-dimensional surveying using a laser scanner. In addition, according to the tunnel construction management method, the management device 20 can display in real time construction methods that serve as countermeasures according to the state of ground deformation.

According to the tunnel construction management method, the management device 20 can display the tunnel excavation impact and tunnel deformation behavior characteristics (1) initial deformation speed, (2) tunnel deformation at the sprayed surface finished form survey position, (3) current excavation incremental deformation, and (4) early closure incremental deformation threshold in an image visualized using color tones, as well as display a construction method to be used as a countermeasure. According to the tunnel construction management method, the next construction method to be used in response to the ground properties and tunnel deformation behavior can be selected in real time based on the display content by the management device 20. According to the tunnel construction management method, the construction method that corresponds to the tunnel deformation behavior based on the survey results can be appropriately selected based on the display content by the management device 20.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention. For example, the tunnel construction management method has been exemplified for the construction of mountain tunnels, but it may also be applied to the construction of tunnels other than mountain tunnels. In addition, the surveying method exemplified in the above embodiment is just one example, and other surveying equipment and methods may be used as long as similar results are obtained.

Reference Signs List 1 Construction Management System 10 Laser Scanner 11 Laser Sensor 12 Main Unit 20 Management Device 21 Calculation Unit 22 Display Unit 23 Memory Unit 30 Total Station B Rock Bolt G Target K Excavation Surface P Steel Pipe Forepiling T Tunnel T1 Face T2 Sprayed Concrete T3 Lining Concrete T4 Invert Sprayed Concrete T5 Invert Concrete

Claims (4)

A step of measuring three-dimensional coordinates of a plurality of measurement points on a construction surface after excavation of a tunnel at least twice at different times;
calculating a deformation behavior of the tunnel based on a difference between the data acquired in the survey;
A step of superimposing a display image corresponding to a threshold value set for the deformation behavior on the three-dimensional image of the tunnel and displaying the display image;
and displaying a construction method according to the state of the deformation behavior ,
As the characteristics of the deformation behavior, threshold values are set for the initial deformation speed, the tunnel deformation at the position of the sprayed surface completed form survey, the current tunnel excavation incremental deformation, and the early closing incremental deformation, and the color tone is changed according to the threshold value .
Tunnel construction management methods. The construction surface includes an excavation surface of the natural ground and a surface of concrete constructed on the excavation surface,
The step of calculating the deformation behavior of the tunnel includes:
A step of measuring a plurality of three-dimensional coordinates on the construction surface corresponding to a virtual unit plane set based on a predetermined length in a circumferential direction and a predetermined length in an extension direction of the tunnel;
calculating an average value of the plurality of three-dimensional coordinates;
and calculating a difference in the average value over time.
A tunnel construction management method according to claim 1. The threshold value is set in stages according to the magnitude of the difference.
A tunnel construction management method according to claim 2. The construction method displayed according to the state of the deformation behavior is selected, and the construction method is applied to the tunnel.
A tunnel construction management method according to any one of claims 1 to 3.

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