Tunnel excavation management method

Abstract

To provide a tunnel excavation management method for accurately selecting a construction method according to the properties of the ground.SOLUTION: A tunnel excavation management method comprises the steps of: performing non-core boring on the ground at a predetermined distance ahead of an excavation direction of a tunnel face; calculating a drilling energy required for drilling a unit volume based on mechanical data in the non-core boring; calculating the collapse scale of the excavated uncut surface of the ground, the physical properties of the ground, and the hardness and softness characteristics based on a value of the drilling energy; constructing a database of a relation between the drilling energy and the collapse scale of the excavation surface and a relation between the drilling energy and ground strength, based on calculation results; calculating a ground strength ratio based on the database and determining a construction method for the ground based on the ground strength ratio; and performing three-dimensional surveying of the excavation surface using a three-dimensional scanner in excavation of the ground for a predetermined distance, and re-evaluating the collapse scale of the excavation surface based on the survey results.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tunnel excavation management method for carrying out a construction method suited to the nature of the ground during excavation. [Background technology]

[0002] When excavating a tunnel, surveying is carried out at each designated excavation stage to ensure that the excavation is proceeding as planned. At tunnel construction sites, where construction is being carried out on constantly changing ground, it is important to collect site information as quickly as possible through accurate observation and surveying, and to manage excavation so that appropriate measures can be taken.

[0003] In the New Austrian Tunneling Method (NATM), which is used to excavate mountain tunnels, the ground to be excavated is classified according to ground grade, and the support pattern to be implemented to prevent collapse is selected according to the ground grade. Standard support patterns and standard construction methods are determined according to each ground grade. The support pattern to be implemented is selected based on visual observation of the ground properties at the face where the excavation surface is exposed, selection of auxiliary excavation work based on the independence of the excavation surface and the scale of crown collapse, and face evaluation points, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-145603 A [Patent Document 2] JP 2017-201074 A Summary of the Invention [Problem to be solved by the invention]

[0005] In unconsolidated ground, the excavation face may become unstable, causing a collapse greater than the overexcavation or a pre-cutting out, which may lead to the collapse of the face. If such a collapse occurs, countermeasures such as spraying concrete or filling voids are carried out. Such countermeasures require a great deal of money, effort, and time, and may be dangerous to the work. Therefore, auxiliary excavation work is considered during construction and is selectively carried out as appropriate.

[0006] On the other hand, in low-strength ground with a ground strength ratio below 1, if a standard support pattern is selected based on face observation and a standard excavation method is used, the tunnel may become unstable, causing excessive displacement and forcing re-construction. In this way, when predicting the nature of the ground ahead of the face based on visual face observation and evaluating the state of the ground, there is an inaccuracy in determining the need for auxiliary excavation work and selecting the support pattern and excavation method optimal for the ground. Therefore, in conventional mountain tunnel excavation management technology, when the ground changes depending on the excavation position or over time, it is difficult to accurately evaluate the ground properties and select a construction method that corresponds to the change in ground properties.

[0007] An object of the present invention is to provide a tunnel excavation management method capable of accurately selecting a support pattern according to the characteristics of the ground being excavated from the face. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention is a tunnel excavation management method comprising the steps of: performing non-core drilling in the ground at a predetermined distance ahead of the excavation direction of the tunnel face; calculating the drilling energy required to drill a unit volume based on machine data from the non-core drilling; calculating the scale of collapse of the excavation surface, natural ground properties, and hardness characteristics of the ground based on the value of the drilling energy; constructing a database of the relationship between the drilling energy and the scale of collapse of the excavation surface, and the relationship between the drilling energy and natural ground strength based on the calculation results; calculating a natural ground strength ratio based on the database and determining a construction method to be applied to the ground based on the natural ground strength ratio; and performing a three-dimensional as-built survey of the excavation surface using a three-dimensional scanner when excavating the ground within the predetermined distance, and reevaluating the scale of collapse of the excavation surface based on the survey results.

[0009] According to the present invention, the need for auxiliary excavation work in the unconstructed ground ahead of the face and an early closure method for the entire cross section can be determined prior to excavation based on the correspondence between the drilling energy of the ground ahead of the face and the scale of collapse at the excavation surface, and between the drilling energy and ground strength.

[0010] In addition, the present invention may include a step of carrying out an in-situ test on the excavation surface in the step of reevaluating the scale of collapse of the excavation surface, and updating the database based on the test results.

[0011] According to the present invention, the database can be updated based on data from previous construction work in correspondence with the drilling energy after excavation, the scale of collapse, and the strength of the ground, thereby improving the estimation accuracy.

[0012] In addition, the drilling energy of the present invention may be calculated by performing the non-core drilling a predetermined number of times over the predetermined distance of the natural ground, acquiring the machine data for each predetermined unit distance, and calculating the average value obtained by statistically processing the machine data at each predetermined interval.

[0013] According to the present invention, by statistically processing the mechanical data obtained from multiple non-core borings as drilling energy, it is possible to calculate the ground strength ratio required for selecting a tunnel support structure. Effect of the Invention

[0014] According to the present invention, a support pattern can be appropriately selected according to the nature of the ground to be excavated from the face. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of a management system according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a block diagram showing a configuration of a management device. [Diagram 3] FIG. 1 is a diagram showing a configuration of a tunnel to be constructed according to an embodiment of the present invention. [Figure 4] FIG. 13 is a diagram showing a method for calculating drilling energy. [Diagram 5] This is a diagram showing the relationship between the depth of collapse of the excavation surface of the ground and the drilling energy. [Figure 6] FIG. 13 is a graph showing the relationship between drilling energy and natural ground strength ratio. [Figure 7] FIG. 1 is a diagram showing a method of three-dimensional surveying. [Figure 8] FIG. 13 is a diagram showing the results of in-situ tests according to the characteristics of the ground. [Figure 9] 1 is a flowchart showing the process flow of a tunnel excavation management method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of a tunnel excavation management method according to the present invention will be described with reference to the drawings. The tunnel excavation management method uses a management system capable of three-dimensionally measuring the shape inside a tunnel. First, the management system will be described.

[0017] As shown in Figure 1, the excavation management system 1 used in the tunnel excavation management method includes a laser scanner 10 (three-dimensional scanner) that surveys the three-dimensional shape inside the tunnel, and a management device 20 that manages the construction of the tunnel based on the survey data from the laser scanner 10.

[0018] The laser scanner 10 includes, for example, a laser sensor 11 that irradiates laser light and receives a portion of the reflected light, and a main body 12 that rotatably supports and rotates the laser sensor 11. The laser sensor 11 includes a laser light emitter (not shown) and a light receiver (not shown). The laser sensor 11 irradiates a target object with laser light in a planar manner while rotating, for example, 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.

[0019] The laser sensor 11 is supported by the main body 12 so as to be rotatable about the y-axis (tilt direction) and is driven to rotate. This allows the laser sensor 11 to scan the target in the up and down directions. The main body 12 is placed on a tripod S. The main body 12 is driven to rotate about the z-axis relative to the tripod S. This allows the laser sensor 11 to be supported so as to be rotatable about the z-axis (horizontal direction) and is driven to rotate.

[0020] In this way, the laser scanner 10 can three-dimensionally scan a predetermined area of ​​the object, and can obtain data on the surface shape of the object in the predetermined area.

[0021] 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 point cloud data is output 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 onto the shoring surface for the second time, for example, and obtains data on the surface shape.

[0022] 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 communicably connected to the laser sensor 11 by wire or wirelessly.

[0023] As shown in Figure 2, 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.

[0024] 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 a storage device such as an HDD (Hard Disk Drive) or a flash memory in advance, or may be stored in a removable storage medium such as a DVD or a CD-ROM, and installed by mounting the storage medium in a drive device. In addition, the computer program may be distributed to a computer via a communication line, and the computer that receives the distribution may execute the program.

[0025] 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, the calculation unit 21 generates image data and numerical data of the three-dimensional shape of the object, and also generates management information by comparing design data and measurement data stored in the storage unit 23. The calculation unit 21 controls the display unit 22 to display the display contents of the generated image data, etc.

[0026] The display unit 22 displays the management information and the image IM of the three-dimensional shape inside the tunnel generated by the calculation unit 21. The display unit 22 is realized by a display device such as a liquid crystal display, an organic EL display, or an LED display.

[0027] The storage 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 items of the tunnel, etc. The storage unit 23 is a storage device such as a HDD, a flash memory, a RAM (Random Access Memory), or a ROM (Read Only Memory).

[0028] As shown in Fig. 3, a face T1 where the natural ground of the excavation target is exposed is formed at the forefront of a tunnel T under construction. The tunnel T is, for example, a mountain tunnel, and the excavation target is a mountain natural ground. In the tunnel excavation management method, the following steps are performed.

[0029] First, non-core boring is performed in the natural ground at a predetermined distance ahead of the excavation direction of the tunnel face T1. Non-core boring is performed by using a drilling machine to drill holes without taking a core (sample) of the natural ground to be cut. Non-core boring is performed a predetermined number of times at different positions on the tunnel face T1. As shown in the figure, non-core boring is performed by drilling holes at five drilling positions C along the outer periphery of the tunnel face T1, for example.

[0030] Non-core drilling is performed to calculate the drilling energy required to drill holes in the natural ground. The drilling energy is the energy required to drill a unit volume based on machine data acquired during drilling. The drilling energy is calculated based on the average value obtained by acquiring machine data for each unit distance of a predetermined distance in the natural ground and statistically processing the machine data for each predetermined interval. Specifically, non-core drilling involves drilling holes at a predetermined distance of, for example, 9 m for each drilling operation. In drilling, machine data detected during drilling is acquired for each predetermined unit distance (for example, every 2 cm interval). The drilling energy is calculated based on the detected machine data.

[0031] As shown in Fig. 4, the drilling energy Ed (N / mm 2) is calculated by statistical processing that calculates the average value of multiple non-core borings at a specified interval (e.g., every 1 m) in the excavation direction. Next, based on the calculated drilling energy value, the scale of collapse (depth) of the excavation surface of the ground, the ground properties, and hardness / softness characteristics are calculated.

[0032] Based on the calculated drilling energy value, the scale of collapse at the excavation surface of the ground, the physical properties of the ground, and the hardness and softness characteristics are visualized numerically. A database is constructed of the relationship between drilling energy and the scale of collapse at the excavation surface, and the relationship between drilling energy and ground strength. Based on the database, the construction method to be applied to the ground is determined. Specifically, based on the database, the scale of collapse relative to drilling energy, ground strength, and ground strength ratio in the unconstructed section ahead of the face are estimated, and the need for auxiliary excavation work and a change to an early closure method for the entire section are considered and determined.

[0033] As shown in Fig. 5, the collapse depth (scale) of the excavation face of the ground is estimated based on the calculated drilling energy Ed in the unconstructed section ahead of the face. This determines the necessity of adopting auxiliary excavation work for the face T1.

[0034] As shown in Figure 6, the natural ground strength ratio cf is estimated based on the drilling energy Ed and calculated from the natural ground strength qu. This determines the need to change to the full-section early closure method for the tunnel face T1. Next, the natural ground is excavated for a specified distance (9 m) in the tunnel T. In the excavation section for this specified distance, the excavation face is observed to determine the natural ground class, and then a 3D completed form survey is performed.

[0035] As shown in Figure 7, a 3D laser scanner (3D scanner: see Figure 1) using laser light is used for 3D as-built surveying, and 3D data of the as-built shape of the excavation surface is obtained. In the surveying, 3D data of the collapse depth around the face is obtained over time. The scale of collapse of the excavation surface and the initial deformation rate are evaluated by observing the 3D data over time. The scale of collapse of the excavation surface is reevaluated by comparing the obtained 3D data of the collapse scale of the excavation surface with the calculation results of the collapse scale of the excavation surface of the ground stored in the database. In addition to the 3D surveying, in-situ tests are conducted at the face position where the ground properties change.

[0036] As shown in Figure 8, in-situ tests are conducted according to the nature of the ground. For example, for clayey ground, a needle penetration test is conducted to estimate the ground strength. For crushed ground, a simple elastic wave test or a point load test is conducted to estimate the ground strength. For ground that has closed early, the axial stress of the shotcrete is measured to estimate the ground strength. The ground strength and ground strength ratio are newly calculated based on the in-situ tests.

[0037] Based on the results of the in-situ test, the natural ground properties are re-evaluated. Specifically, based on the data obtained by the in-situ test, a natural ground strength ratio associated with the drilling energy at that position is calculated, and the excavation method and tunnel support structure corresponding to the natural ground strength ratio, which is a numerical representation of the natural ground properties, are evaluated. The database is updated based on the recalculated values ​​based on the data obtained by the in-situ test. The use of the updated database improves prediction accuracy. As shown in the figure, the condition of the face T1 is evaluated for each progress of excavation of the face T1 based on the natural ground strength ratio.

[0038] FIG. 9 shows the process flow of the tunnel excavation management method. The tunnel excavation management method includes the following steps. First, a step of performing non-core boring is performed in the natural ground at a predetermined distance ahead of the excavation direction of the face T1 of the tunnel T (step S10). The management device 20 calculates the drilling energy required to drill a unit volume based on the machine data in the non-core boring (step S12). The management device 20 calculates the collapse scale of the excavation surface of the natural ground, the natural ground properties, and the hardness / softness characteristics based on the value of the drilling energy (step S14).

[0039] In the management device 20, a database of the relationship between drilling energy and the scale of collapse of the excavation surface, and the relationship between drilling energy and natural ground strength is constructed based on the calculation results (step S16). In the management device 20, a natural ground strength ratio is calculated based on the database, and a construction method to be applied to the natural ground is determined (step S18). A 3D completed form survey is performed on the excavation surface when the natural ground is excavated for a predetermined distance, and the scale of collapse of the excavation surface is reevaluated based on the survey results (step S20). An in-situ test is performed on the excavation surface based on a test method according to the nature of the natural ground, and the management device 20 updates the database based on the test results (step S22). After the natural ground is excavated for a predetermined distance, the above steps are repeatedly executed.

[0040] As described above, according to the tunnel excavation management method, the necessity of auxiliary excavation work in the unconstructed ground ahead of the face and the early closure method for the entire cross section can be determined before excavation based on the correspondence between the drilling energy of the ground ahead of the face, the scale of collapse at the excavation surface, and the drilling energy and the ground strength. According to the tunnel excavation management method, the database can be updated based on the data of the existing work with the correspondence between the drilling energy, the scale of collapse, and the ground strength after excavation, and the estimation accuracy can be improved.

[0041] 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 present invention. For example, although a mountain tunnel is exemplified in the above embodiment, the present invention may be applied to tunnel construction other than mountain tunnels. [Explanation of symbols]

[0042] 1. Drilling Management System 10. Laser Scanner 20 Management device T-Tunnel T1 Face C Drilling position

Claims

1. A step of performing non-core boring in the ground at a predetermined distance forward from the excavation direction of the tunnel face; A step of calculating drilling energy required for drilling a unit volume based on machine data in the non-core boring; A step of calculating the scale of collapse of the excavation surface of the ground, the physical properties of the ground, and the hardness and softness characteristics of the ground based on the value of the drilling energy; A step of constructing a database of the relationship between the drilling energy and the scale of collapse of the excavation surface, and the relationship between the drilling energy and the strength of the natural ground, based on the calculation results; A step of calculating a ground strength ratio based on the database, and determining a construction method to be applied to the ground based on the ground strength ratio; A process of performing a three-dimensional completed survey of the excavation surface using a three-dimensional scanner during excavation of the natural ground over the predetermined distance, and re-evaluating the scale of collapse of the excavation surface based on the survey results, A tunnel excavation management method comprising a step of carrying out an in-situ test on the excavation surface in a step of reevaluating the scale of collapse of the excavation surface, calculating a ground strength ratio associated with the drilling energy at that position based on the test results, evaluating the excavation method and tunnel support structure corresponding to the ground strength ratio which is a numerical representation of the ground properties, and updating the database based on recalculated values ​​based on the data obtained by the in-situ test.

2. The drilling energy is calculated based on an average value obtained by performing the non-core boring for the predetermined distance of the natural ground a predetermined number of times, acquiring the machine data for each predetermined unit distance, and statistically processing the machine data for each predetermined interval. A tunnel excavation management method according to claim 1.

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