JP7707488B2 - Method and system for evaluating the soundness of tunnel supports - Google Patents

Description

The present invention relates to a tunnel support integrity evaluation method and integrity evaluation system.

In the construction of mountain tunnels, it is common to carry out underground measurements to grasp the characteristics (or condition, behavior, etc.) of the ground, such as visually observing the tunnel face and measuring the deformation or stress state of the supports and the ground.
Tunnel construction management is carried out by, for example, setting management reference values for tunnel displacement using the direct strain method, and then measuring the tunnel displacement as it progresses and comparing the measured values with the management reference values. However, setting management reference values for tunnel displacement using the direct strain method is intended to ensure the stability of the ground, and is not intended to evaluate the soundness of the shoring that supports the tunnel. By properly evaluating the soundness of the shoring that supports the tunnel at each excavation stage, tunnel construction with high construction safety can be achieved.

Here, Patent Document 1 proposes a method for predicting the final displacement of a tunnel, which provides a method for predicting the displacement of a mountain tunnel at a tunnel site. Specifically, the method includes a first step of performing a three-dimensional finite element method simulation analysis reflecting the excavation progress status using a three-dimensional finite element method model arbitrarily set as a standard model, and obtaining a relationship equation between the initial displacement speed and the ground stiffness ratio of each measurement point and at least a relationship equation between the final displacement and the ground stiffness ratio for each ground type, support structure, and excavation method; a second step of acquiring initial displacement speed data for each measurement point by measurement using a 3D laser scanner installed in front of the face after excavation of the tunnel; and a third step of calculating the ground stiffness ratio of the excavation part by fitting it to the relationship equation between the initial displacement speed and the ground stiffness ratio obtained in the first step, and calculating the final displacement of each measurement point based on the relationship equation between the final displacement and the ground stiffness ratio.

JP 2016-121487 A

The prediction method described in Patent Document 1 predicts the final displacement of a tunnel, but as mentioned above, does not evaluate the soundness of the support structure that supports the tunnel at each excavation stage.

The present invention aims to provide a tunnel support integrity evaluation method and system that can properly evaluate the integrity of the tunnel support at each excavation stage.

In order to achieve the above object, one aspect of the tunnel support soundness evaluation method according to the present invention includes:
A method for evaluating the soundness of a tunnel support, comprising: identifying stress in a support constructed in association with excavation of a tunnel and evaluating the soundness of the support;
Step A includes capturing an image of the measurement position of the support set for each excavation stage of the tunnel using a three-dimensional laser scanner to obtain three-dimensional coordinates, determining the amount of displacement at the measurement position for each excavation stage, and determining the incremental amount of displacement as the excavation stage progresses;
A step B includes creating a support model for the support in a computer and calculating stress generated in the support model for each excavation stage by applying the incremental displacement to the support model;
The method is characterized by having a step C of evaluating the soundness of the support structure based on the calculated stress for each excavation stage.

According to this aspect, a three-dimensional laser scanner is used to obtain three-dimensional coordinates of the measurement position of the shoring for each excavation stage of the tunnel to identify the amount of displacement, and after identifying the incremental displacement amount as the excavation stage progresses, the incremental displacement amount is applied to the shoring model, and the stress generated in the shoring model for each excavation stage is calculated to evaluate the soundness of the shoring, thereby making it possible to properly evaluate the soundness of the shoring for each excavation stage. Here, the three-dimensional coordinates of the three-dimensional laser scanner are obtained in advance by a traverse survey or the like, and the three-dimensional coordinates of the measurement position of the shoring are identified by the three-dimensional laser scanner having the three-dimensional coordinates.
By applying a three-dimensional laser scanner, it becomes unnecessary to install measuring equipment at each measurement position in the shoring, and it becomes possible to quickly measure displacement at each measurement position. Conventional stress measurement of shoring is performed by attaching a stress meter to each position of the shoring and burying the stress meter in the shotcrete (secondary shotcrete), which means that it is impossible to measure stress at various measurement positions in the shoring, and it is also impossible to change the measurement position at any time. Furthermore, since the stress meter installed in the shoring is basically left inside the secondary shotcrete (buried), various problems exist, such as the time and effort required to install the stress meter and the cost required for stress measurement. By applying a three-dimensional laser scanner, all of these problems can be solved.
By performing stress analysis by applying incremental displacements as the excavation stage progresses to a computer-created shoring model, it is possible to accurately identify the stress occurring throughout the entire shoring area through back analysis of the shoring stress. Here, the shoring model includes a two-dimensional beam-spring model, a two-dimensional or three-dimensional FEM (Finite Element Method) analysis model, etc.

Another aspect of the tunnel support soundness evaluation method according to the present invention is to
In the step B,
The support includes shotcrete and steel support;
The support model includes a shotcrete model and a steel support model,
Calculating stresses in each of the excavation stages of the shotcrete model and the steel support model;
In the step C,
The method is characterized in that the soundness of the sprayed concrete and the steel support are evaluated.

According to this aspect, the soundness of each support can be properly evaluated by specifying the displacement amount at the measurement position of the shotcrete and steel support included in the support, the incremental displacement amount as the excavation stage progresses, and specifying the stress actually occurring in each support by back-analysis of the stress of each support. Therefore, for example, if the stress occurring in both the shotcrete and the steel support is greater than the yield strength of each, measures such as reviewing the specifications of both supports will be taken, and if only the steel support is unsuitable, measures can be taken only for the steel support.
If the soundness of the sprayed concrete is assessed as insufficient, there is a risk of the sprayed concrete cracking or spalling, and if the soundness of the steel supports is assessed as insufficient, there is a risk of the steel supports deforming or buckling.

Another aspect of the tunnel support soundness evaluation method according to the present invention is to
In the step B,
The support model is created as a three-dimensional model,
The method is characterized in that the incremental displacement amount is applied to the support model in a planar manner.

According to this aspect, by applying incremental displacement amounts to a three-dimensional model of the support (such as an FEM analysis model), it is possible to obtain analysis results with even higher accuracy and to more precisely evaluate the soundness of the support.

Another aspect of the tunnel support soundness evaluation method according to the present invention is to
Step D: setting an allowable strain when the support is damaged based on a plurality of tunnel construction cases in which damage to the support has been confirmed;
The method further includes a step E of setting a management reference value of the support by multiplying the allowable strain by the excavation radius of the tunnel to be managed,
In step C, in addition to evaluating the soundness of the support based on the calculated stress for each excavation stage, the soundness of the support is evaluated by comparing the control standard value with the amount of displacement at the measurement position for each excavation stage.

According to this embodiment, in addition to evaluating the soundness of the shoring based on the stress at each excavation stage, an evaluation of the soundness is also performed based on a comparison of the measured values regarding the displacement of the shoring with the control standard value. For example, if both evaluations are favorable, the shoring is deemed to be sound, and if at least one of the evaluations is unfavorable, the shoring is deemed to be unsound, thereby achieving an even more reliable soundness evaluation.
In addition, in this embodiment, the allowable strain when the shoring is damaged is set from multiple tunnel construction cases where damage to the shoring has been confirmed, and the allowable strain is multiplied by the excavation radius of the tunnel to be managed to set the control standard value for the shoring, thereby making it possible to set a control standard value that reflects the strain when the shoring is damaged and the scale (excavation radius) of the tunnel to be managed and that allows the soundness of the shoring to be evaluated.The soundness of the shoring can be properly evaluated by comparing this control standard value with the measured value of the displacement of the shoring associated with the excavation of the tunnel to determine whether the shoring is suitable or not.

Here, "multiple tunnel construction cases" include not only the past tunnel construction records held by construction companies, but also tunnel construction cases where damage to shoring has been confirmed that have been published by the Japan Tunneling Association, the Japan Society of Civil Engineers, etc. Shoring includes sprayed concrete, steel shoring, rock bolts, etc., and "damage to shoring" includes, as mentioned above, cracks and spalling of sprayed concrete, deformation and buckling of steel shoring, deformation of rock bolt washers, and breakage of rock bolts, etc.

The strain when the support is damaged (displacement of the support (or tunnel wall) / tunnel excavation radius) can be set to, for example, 2% or less (approximately 1 to 2%).

In addition, one aspect of the tunnel support soundness evaluation system according to the present invention is to
A tunnel support integrity evaluation system that identifies stress in a support constructed during tunnel excavation and evaluates the integrity of the support,
A three-dimensional laser scanner and an evaluation device are included.
The three-dimensional laser scanner includes:
At each stage of excavation of the tunnel, the measurement position of the set support is imaged by a three-dimensional laser scanner to obtain three-dimensional coordinates;
The evaluation device includes:
A displacement amount specifying unit that specifies a displacement amount at the measurement position for each excavation stage and specifies an incremental displacement amount as the excavation stage progresses;
A stress calculation unit that creates a support model for the support and calculates a stress generated in the support model for each excavation stage by applying the incremental displacement amount to the support model;
The present invention is characterized in that it has an evaluation unit that evaluates the soundness of the support structure based on the stress calculated for each excavation stage.

According to this aspect, a 3D laser scanner is used to obtain the 3D coordinates of the measurement position of the support for each excavation stage of the tunnel to determine the amount of displacement, and the evaluation device determines the incremental displacement amount as the excavation stage progresses, assigns the incremental displacement amount to the created support model, and calculates the stress generated in the support model for each excavation stage to evaluate the soundness of the support, thereby making it possible to properly evaluate the soundness of the support for each excavation stage.

In another aspect of the tunnel support integrity evaluation system according to the present invention,
The evaluation device includes:
A storage unit for storing a plurality of tunnel construction examples in which damage to the support structure has been confirmed;
An allowable strain setting unit that sets an allowable strain when the support is damaged based on the plurality of tunnel construction examples;
and a management reference value setting unit that sets a management reference value for the support by multiplying the allowable strain by an excavation radius of a tunnel to be managed,
The evaluation unit is characterized in that in addition to evaluating the soundness of the support based on the calculated stress for each excavation stage, the evaluation unit also evaluates the soundness of the support by comparing the control standard value with the amount of displacement at the measurement position for each excavation stage.

According to this embodiment, in addition to evaluating the soundness based on the stress of the support at each excavation stage, the soundness is evaluated based on a comparison between the measured values of the displacement of the support and the control standard value, thereby achieving a more reliable soundness evaluation.

The tunnel support integrity evaluation method and system of the present invention make it possible to properly evaluate the integrity of the tunnel support at each excavation stage.

1 is an overall configuration diagram showing an example of a tunnel support soundness evaluation system according to an embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of a computer constituting the soundness evaluation system. FIG. 2 is a diagram illustrating an example of a functional configuration of an evaluation device constituting the soundness evaluation system. FIG. 13 is a diagram showing an example of display on the display unit when an incremental displacement amount is applied as a forced displacement to an FEM analysis model of a support structure. FIG. 13 is a diagram showing an example of the display of calculation results of support stress on the display unit. This is an example of a tunnel construction example, and is a table summarizing construction examples based on past construction results. 1 is a flowchart of an example of a tunnel support integrity evaluation method according to the first embodiment. 13 is a flowchart of an example of a tunnel support integrity evaluation method according to the second embodiment.

Below, the tunnel support soundness assessment system and method according to the embodiment will be described with reference to the attached drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant explanation.

[Tunnel support soundness evaluation system according to the embodiment]
First, an example of a tunnel support soundness evaluation system according to an embodiment will be described with reference to Fig. 1 to Fig. 6. Here, Fig. 1 is an overall configuration diagram showing an example of a tunnel support soundness evaluation system according to an embodiment. Fig. 2 is a diagram showing an example of a hardware configuration of a computer constituting the soundness evaluation system, and Fig. 3 is a diagram showing an example of a functional configuration of an evaluation device constituting the soundness evaluation system.

The soundness assessment system 100 is a soundness assessment system that identifies the stress of supports constructed during tunnel excavation and evaluates the soundness of the supports.

The soundness assessment system 100 has a three-dimensional laser scanner 10 and an evaluation device 20. The illustrated example of the soundness assessment system 100 is configured such that the three-dimensional laser scanner 10 and the evaluation device 20 are connected to be able to send and receive measurement data via a network 30. Here, the three-dimensional laser scanner 10 and the evaluation device 20 may not be connected via the network 30, and may send and receive data via a wired connection.

The three-dimensional laser scanner 10 emits a laser to multiple measurement positions set on the support structure, receives the reflected laser, and obtains the three-dimensional coordinates of the measurement positions. More precisely, the three-dimensional coordinates of the three-dimensional laser scanner 10 are determined by a traverse survey or the like, and the three-dimensional coordinates of the multiple measurement positions on the support structure are determined by the three-dimensional laser scanner 10 having the three-dimensional coordinates.

The evaluation device 20 has various functions as shown in FIG. 3, which are described in detail below. Both the 3D laser scanner 10 and the evaluation device 20 are configured using computers, but the following explanation, which refers to FIG. 2, focuses on the evaluation device 20.

The personal computer constituting the evaluation device 20 includes a CPU (Central Processing Unit) 21, a main memory device 22, an auxiliary memory device 23, a communication IF 24, and an input/output IF (interface) 25, which are interconnected by a connection bus 26. The main memory device 22 and the auxiliary memory device 23 are computer-readable recording media. Note that each of the above components may be provided separately, or some of the components may not be provided.

The CPU 21 is also called an MPU (Microprocessor) or a processor, and may be a single processor or a multiprocessor. The CPU 21 is a central processing unit that performs overall control of the evaluation device 20. The CPU 21 provides functions that meet a specified purpose, for example, by expanding a program stored in the auxiliary storage device 23 in an executable manner in the working area of the main storage device 22, and controlling peripheral devices through the execution of the program.

The main memory 22 stores the computer programs executed by the CPU 21 and the data processed by the CPU 21. The main memory 22 includes, for example, a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary memory 23 stores various programs and various data in a readable and writable recording medium, and is also called an external memory device. The auxiliary memory 23 stores, for example, an OS (Operating System), various programs, various tables, and the like. The OS includes, for example, a communication interface program that transfers data to and from external devices connected via the communication IF 24. External devices for the evaluation device 20 include the three-dimensional laser scanner 10, a host computer in the department to which the measurer belongs, and smartphones and tablets carried by other measurers, etc.

The auxiliary storage device 23 is used, for example, as a storage area that supports the main storage device 22, and stores computer programs executed by the CPU 21, data processed by the CPU 21, etc. The auxiliary storage device 23 is a silicon disk including a non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), a hard disk drive (HDD: Hard Disk Drive) device, a solid state drive device, etc. Examples of the auxiliary storage device 23 include drives for removable recording media such as CD drives, DVD drives, and BD drives, and examples of removable recording media include CDs, DVDs, BDs, USB (Universal Serial Bus) memories, and SD (Secure Digital) memory cards, etc.

The input/output IF 25 is an interface that inputs and outputs data between devices connected to the evaluation device 20. Input devices such as a keyboard, a touch panel, a mouse, or other pointing device, and a microphone are connected to the input/output IF 25. The evaluation device 20 receives operation instructions, etc. from an operator who operates the input device via the input/output IF 25.

The input/output IF 25 is also connected to display devices such as liquid crystal displays (LCDs) and organic electroluminescence (EL) panels, as well as output devices such as printers and speakers. The evaluation device 20 is configured to continuously display the results of stress calculations and soundness evaluations of the support for each of the multiple excavation stages.

The communication IF 24 is an interface with the network to which the evaluation device 20 is connected. The communication IF 24 receives measurement values by the three-dimensional laser scanner 10 via various networks, such as public networks such as the Internet, wireless networks such as mobile phone networks, dedicated networks such as VPNs (Virtual Private Networks), and LANs (Local Area Networks), and transmits data related to the stress calculation results and soundness evaluation results of the support to a host computer, etc. Here, an LPWA wireless communication module and a communication antenna, etc. may be connected to the communication IF 24. The LPWA wireless communication module is a device that realizes LPWA wireless communication (wireless transmission), and is, for example, an electronic component in which a wireless chip and peripheral circuits are mounted on a small substrate. The main communication methods (communication protocols) for LPWA include Sigfox, LoRaWAN (Long Range Wide Area Network), NB-IoT, etc., but it is preferable to use LoRaWAN, which does not require a license, allows for the installation of self-operated base stations inside mines even in mountainous areas where mobile phone communication waves are difficult to reach, and allows the construction of a low-cost communication system. LoRaWAN is a communication method that uses LoRa modulation, using the 920 MHz ISM band and enabling long-distance communication even with low output of 13 dBm or less.

As shown in FIG. 3, the evaluation device 20 provides various functions, at least a communication unit 202, a displacement amount determination unit 204, a stress calculation unit 206, an evaluation unit 208, an allowable strain setting unit 210, a control standard value setting unit 212, a display unit 214, and a storage unit 216, by executing a program by a CPU 21. Here, at least a part of the above processing functions may be provided by a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), etc., and similarly, at least a part of the above processing functions may be a dedicated LSI (large scale integration) such as an FPGA (Field-Programmable Gate Array), a numerical calculation processor, an image processing processor, or other digital circuit, etc.

The communication unit 202 receives measurement data (measurement values) relating to the three-dimensional coordinates at each measurement position of the support work transmitted from the three-dimensional laser scanner 10 at any time, and stores the data in the storage unit 216 at any time.

The displacement amount determination unit 204 determines the amount of displacement for each excavation stage at each measurement position based on the three-dimensional coordinates and the amount of change in coordinates at multiple measurement positions of the support, which are measured for each excavation stage, and determines the incremental displacement amount as the excavation stage progresses at each measurement position of each support. For example, the incremental displacement amount for each excavation stage is determined by measuring the three-dimensional coordinates of multiple measurement positions of steel support, which are erected at intervals of several meters, for each of the multiple excavation stages.

The stress calculation unit 206 creates a support model for the support and calculates the stress generated in the support model for each excavation stage by applying an incremental displacement amount to the support model.

Here, FIG. 4 shows an example of the display on the display unit 214 when an incremental displacement amount is applied as a forced displacement to the FEM analysis model of the shoring. The shoring model M in the illustrated example is a two-dimensional or three-dimensional FEM analysis model, and is a model diagram of the case when an incremental displacement amount is forcedly applied to the shoring model M, which has a horseshoe-shaped cross section.

Here, if the shoring includes shotcrete and steel shoring, the shoring model M will be a stacked beam model of the shotcrete model and the steel shoring model. For the steel shoring model, ν (Poisson's ratio), E (Young's modulus), A (cross-sectional area), I (second moment of area), etc. are set according to its specifications, and for the shotcrete model, ν, E, A, etc. are set according to its specifications. Note that for shotcrete, Young's modulus E needs to be assumed since it changes with the age of the material, and the cross-sectional area A also needs to be assumed taking into account uneven thickness.

When a three-dimensional FEM analysis model (three-dimensional model) is created, more accurate stress analysis results can be obtained by applying incremental displacement amounts to the three-dimensional support model.

As shown in Fig. 4, by applying an incremental displacement amount to the support model M as a forced displacement, the stress generated in the support model is calculated as shown in Fig. 5. In the illustrated example, a maximum bending stress of 274 N/ ^mm2 is generated in the steel support model of the support model M.

The storage unit 216 stores, for example, yield strength data (e.g., 400 N/mm ² ) of the steel support, and the evaluation unit 208 evaluates the soundness of the steel support by comparing the calculated maximum bending stress of 274 N/mm ² with the yield strength of 400 N/mm ^2. In this example, since the maximum bending stress is equal to or less than the yield strength, the steel support is evaluated as sound.

Storage section 216 stores multiple tunnel construction examples where damage to supports has been confirmed.

Figure 6 shows an example of a tunnel construction example, and more specifically, it is a table that lists construction examples based on past construction results.

Figure 6 shows the soil cover, geology, deformation position of support members (shoring), face separation, tunnel conversion radius (for example, the radius when a horseshoe-shaped tunnel is simulated as a circle), support pattern (shoring pattern) at the time of deformation, and measured displacement for 26 cases from A tunnel to Z tunnel, and the "circumferential strain" in the right column is calculated from the tunnel conversion radius and measured displacement. Note that "circumferential strain" refers to the radial strain at multiple points around the circumference of the tunnel (top, inner space, wall surface). There are other construction examples based on construction performance compiled by the inventors other than the example shown in Figure 6, but Figure 6 shows one example.

The method for calculating the circumferential strain: εt (%) is to divide the measured displacement of the tunnel (radial displacement): Ur (m) by the tunnel excavation radius (or converted radius, in m): R, and multiply it by 100.

Although illustrations are omitted, the construction examples include examples described in publicly available literature. Examples of such publicly available literature include the construction examples described in Japan Tunneling Association: Tunnels and Underground, Japan Society of Civil Engineers: Tunnel Engineering Research Presentation Papers and Reports, Japan Tunneling Association: Construction Experience Presentation, etc.

In the allowable strain setting unit 210, the allowable strain when the support is damaged is set, for example, in the range of 1% to 2% based on the multiple construction examples described above. Here, by setting the allowable strain to 2%, a dangerous management standard value based on tunnel construction examples can be set, and by setting the allowable strain to 1%, a safe management standard value based on tunnel construction examples can be set. The allowable strain setting unit 210 may automatically set an appropriate allowable strain for the tunnel to be managed, in the range of about 1% to 2%, or the allowable strain set by a construction manager, etc., in the range of about 1% to 2% may be input to the allowable strain setting unit 210.

It is also possible to allow for a safety factor of, for example, 1% strain, and by allowing for a safety factor, a safer control standard value can be set. Here, the safety factor can be set to approximately 1.1 to 1.5, and for example, if a safety factor of 1.25 is allowed for 1% strain, the allowable strain is set to 0.8%.

The management standard value setting unit 212 sets the management standard value for the support by multiplying the allowable strain set in the allowable strain setting unit 210 by the excavation radius of the tunnel to be managed.

As described above, the evaluation unit 208 evaluates the soundness of the support structure based on the calculated stress for each excavation stage, and also evaluates the soundness of the support structure by comparing the displacement amount at the measurement position for each excavation stage with the set management standard value.

For example, by carrying out a two-stage evaluation of the soundness of a support, if both soundness evaluations are met, the support can be determined to be sound. If at least one of the soundness evaluations is not met, the support is determined to be unsound, and countermeasures will be considered and implemented.

The illustrated evaluation device 20 has a two-stage support soundness evaluation function, but may have a form that does not include, for example, the allowable strain setting unit 210 and the control standard value setting unit 212. In this form, the soundness of the support is evaluated based only on the calculated stress for each excavation stage.

According to the soundness evaluation system 100, the three-dimensional laser scanner 10 is used to obtain the three-dimensional coordinates of the measurement position of the support for each excavation stage of the tunnel to determine the amount of displacement, and the evaluation device 20 determines the incremental displacement amount as the excavation stage progresses, assigns the incremental displacement amount to the created support model M, and calculates the stress generated in the support model M for each excavation stage to evaluate the soundness of the support, thereby making it possible to properly evaluate the soundness of the support for each excavation stage.

In addition, by applying the three-dimensional laser scanner 10, it becomes unnecessary to install measuring equipment at each of the various measurement positions in the support structure, and it becomes possible to quickly measure displacement at each measurement position.

[Method for evaluating the soundness of tunnel support according to the first embodiment]
Next, an example of the tunnel support soundness evaluation method according to the first embodiment will be described with reference to Fig. 7. Here, Fig. 7 is a flowchart of the example of the tunnel support soundness evaluation method according to the first embodiment.

This method of evaluating soundness identifies the stresses in the supports that are constructed during tunnel excavation and evaluates the soundness of the supports.

First, at each stage of tunnel excavation, the measurement positions of the set supports are imaged using a 3D laser scanner to obtain 3D coordinates (step S10).

Then, the amount of displacement at the measurement position for each excavation stage is determined, and the incremental amount of displacement as the excavation stage progresses is determined (step S12). Steps S10 and S12 are collectively referred to as process A.

Next, a support model for the support is created in the computer, and the stress generated in the support model at each excavation stage is calculated by applying an incremental displacement to the support model (step S14, process B).

Next, the soundness of the support is evaluated based on the calculated stresses for each excavation stage (step S16, process C).

If the evaluation of the soundness of the support structure shows that the stress exceeds the yield strength, for example, the support structure is deemed to be unsound, and some kind of countermeasure is considered and implemented (step S18). On the other hand, if the stress is equal to or less than the yield strength, the current support structure can be evaluated as sound.

[Method of evaluating the soundness of tunnel support according to the second embodiment]
Next, an example of the tunnel support soundness evaluation method according to the second embodiment will be described with reference to Fig. 8. Here, Fig. 8 is a flowchart of an example of the tunnel support soundness evaluation method according to the second embodiment.

In Figure 8, the flowchart in the left column is essentially the same as the flowchart shown in Figure 7. This flow in the left column is used to evaluate the soundness of the first stage of support (step S16).

In the flowchart on the right side of Figure 8, the allowable strain in the event of support damage is set based on multiple tunnel construction examples in which support damage has been confirmed. The allowable strain should be set in the range of about 1% to 2%, and if an additional safety factor is required, a safer allowable strain is set (step S20, process D).

Next, the allowable strain is multiplied by the excavation radius of the tunnel to be managed to set the support management standard value (step S22, process E).

Next, for each stage of excavation of the tunnel, the measurement positions of the set support are imaged using a 3D laser scanner to obtain 3D coordinates (step S24), and the soundness of the second stage of support is evaluated by comparing the displacement at the measurement positions for each excavation stage with the management standard values (step S26, process C).

Finally, it is determined whether at least one of the results of the soundness assessment of the first and second stages of support is sound (step S30), and if neither is assessed to be sound, some kind of countermeasure work is considered and implemented (step S18). On the other hand, if either one or both are assessed to be sound, the current support can be assessed to be sound.

This soundness assessment method makes it possible to achieve more accurate assessment of the soundness of support structures.

Note that the configurations described in the above embodiments may be combined with other components, and the present invention is not limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately according to the application form.

10: 3D laser scanner 20: Evaluation device 30: Network 100: Tunnel support soundness evaluation system (soundness evaluation system)
202: Communication unit 204: Displacement amount determination unit 206: Stress calculation unit 208: Evaluation unit 210: Allowable strain setting unit 212: Control standard value setting unit 214: Display unit 216: Storage unit M: Support model

Claims (6)

A method for evaluating the soundness of a tunnel support, comprising: identifying stress in a support constructed in association with excavation of a tunnel and evaluating the soundness of the support;
Step A includes capturing an image of the measurement position of the support set for each excavation stage of the tunnel using a three-dimensional laser scanner to obtain three-dimensional coordinates, determining the amount of displacement at the measurement position for each excavation stage, and determining the incremental amount of displacement as the excavation stage progresses;
A step B includes creating a support model for the support in a computer and calculating stress generated in the support model for each excavation stage by applying the incremental displacement to the support model;
A method for evaluating the integrity of a tunnel support, comprising a step C of evaluating the integrity of the support based on the stress calculated for each excavation stage. In the step B,
The support includes shotcrete and steel support;
The support model includes a shotcrete model and a steel support model,
Calculating stresses in each of the excavation stages of the shotcrete model and the steel support model;
In the step C,
2. A method for evaluating the integrity of a tunnel support according to claim 1, characterized in that the integrity of each of the sprayed concrete and the steel support is evaluated. In the step B,
The support model is created as a three-dimensional model,
3. The method for evaluating the soundness of a tunnel support according to claim 1, further comprising the step of applying the incremental displacement amount to the support model in a planar manner. Step D: setting an allowable strain when the support is damaged based on a plurality of tunnel construction cases in which damage to the support has been confirmed;
The method further includes a step E of setting a management reference value of the support by multiplying the allowable strain by the excavation radius of the tunnel to be managed,
4. A method for evaluating the integrity of a tunnel support as described in any one of claims 1 to 3, characterized in that in step C, in addition to evaluating the integrity of the support based on the calculated stress for each excavation stage, the integrity of the support is evaluated by comparing the control standard value with the amount of displacement at the measurement position for each excavation stage. A tunnel support integrity evaluation system that identifies stress in a support constructed during tunnel excavation and evaluates the integrity of the support,
A three-dimensional laser scanner and an evaluation device are included.
The three-dimensional laser scanner includes:
At each stage of excavation of the tunnel, the measurement position of the set support is imaged by a three-dimensional laser scanner to obtain three-dimensional coordinates;
The evaluation device includes:
A displacement amount specifying unit that specifies a displacement amount at the measurement position for each excavation stage and specifies an incremental displacement amount as the excavation stage progresses;
A stress calculation unit that creates a support model for the support and calculates a stress generated in the support model for each excavation stage by applying the incremental displacement amount to the support model;
A tunnel support integrity evaluation system, characterized by having an evaluation unit that evaluates the integrity of the support based on the stress calculated for each excavation stage. The evaluation device includes:
A storage unit for storing a plurality of tunnel construction examples in which damage to the support structure has been confirmed;
An allowable strain setting unit that sets an allowable strain when the support is damaged based on the plurality of tunnel construction examples;
and a management reference value setting unit that sets a management reference value for the support by multiplying the allowable strain by an excavation radius of a tunnel to be managed,
The tunnel support integrity evaluation system of claim 5, characterized in that the evaluation unit evaluates the integrity of the support based on the calculated stress for each excavation stage, and also evaluates the integrity of the support by comparing the control standard value with the displacement amount at the measurement position for each excavation stage.