Tunnel structure three-direction displacement monitoring device and method

Abstract

The invention relates to a tunnel structure three-way displacement monitoring device and method.The device comprises tripods and optical fiber monitors, the multiple tripods are fixedly installed on the inner wall of a tunnel at intervals, each tripod is provided with an anchoring device, an optical fiber is connected between every two adjacent tripods through the corresponding anchoring device, and the tail ends of the optical fibers are connected with the optical fiber monitors; the optical fiber monitor is an optical fiber strain monitoring device, the monitoring method obtains the strain variation of the optical fibers connected and arranged according to a certain rule through the optical fiber monitor, the displacement of the optical fibers penetrating through the tripod is calculated through the optical fiber strain variation, and then the displacement of the tunnel is obtained. Compared with the prior art, the three-direction displacement monitoring device has the advantages of simple structure, convenience in operation and the like, and can perform three-direction displacement monitoring on the curved tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel monitoring, and in particular to a device and method for monitoring three-dimensional displacement of a tunnel structure. Background Art

[0002] During tunnel construction, due to the complex relationship between surrounding rock and support, as well as geological changes, improper construction and other factors, the tunnel structure may be displaced, deformed or even unstable, requiring displacement monitoring of the tunnel.

[0003] Tunnel structure displacement monitoring is a process of real-time tracking and recording of the displacement and deformation of tunnel structures during construction and operation through certain technical means and instruments and equipment. It is crucial to ensure the safety of tunnel construction and operation. Tunnel structure displacement monitoring can detect structural anomalies in real time and take timely measures to ensure the safety of construction workers. Monitoring data can also be used to evaluate the stability of the tunnel, optimize construction plans, avoid long-term settlement and deformation, and ensure the long-term safe use of the tunnel. At the same time, displacement monitoring also helps to meet relevant regulatory requirements, detect potential risks in advance, and improve the maintenance and management efficiency of the tunnel.

[0004] The commonly used tunnel structure displacement monitoring methods are:

[0005] Manual total station monitoring: a series of measuring points are set up in the tunnel, and the coordinates of the measuring points are measured by manually operating the total station, and the displacement is analyzed by comparing the changes in their coordinates. This method has a large workload, low work efficiency, time-consuming and labor-intensive, and limited detection accuracy.

[0006] Non-contact visual monitoring: bury prism targets in the tunnel, and use laser or machine vision instruments to observe the displacement changes of the targets. This type of monitoring method requires that the instrument and the target can be in line of sight. For tunnels with bends or internal obstructions, multiple observation instruments need to be set up, which increases the workload and cost; the instrument and the target are required to be relatively still, and their accuracy is easily affected by vibration.

[0007] Patent CN118687516A proposes a planar displacement monitoring system and method for a sharp curve tunnel segment, which uses a displacement sensor parallel to the tunnel axis to detect the relative posture of each segment ring in the tunnel. However, this method can only obtain a plan view of the position and posture of each tunnel structure, and cannot perform detection in three-dimensional space.

[0008] Patent CN118328973A proposes a tunnel segment displacement detection device and mentions a contact measurement method, that is, setting multiple coplanar detection points on the arc surface composed of the tunnel segments, and detecting whether these measurement points are still in the same plane by translating the displacement sensor. This method can only detect the displacement of one dimension of the tunnel, and it is necessary to translate the displacement sensor in the tunnel, which has certain requirements on the flatness of the tunnel. Summary of the invention

[0009] The purpose of the present invention is to provide a three-dimensional displacement monitoring device and method for a tunnel structure in order to overcome the defect of the above-mentioned prior art that the displacement of the tunnel in three-dimensional space cannot be detected.

[0010] The purpose of the present invention can be achieved by the following technical solutions:

[0011] According to one aspect of the present invention, there is provided a three-dimensional displacement monitoring device for a tunnel structure, comprising a tripod and a fiber optic monitor. There are multiple tripods and they are fixedly installed on the inner wall of the tunnel at intervals. Each tripod is provided with an anchoring device. An optical fiber is connected between two adjacent tripods via the anchoring device. The end of the optical fiber is connected to the fiber optic monitor. The fiber optic monitor is a fiber optic strain monitoring device.

[0012] Furthermore, the tripod is L-shaped, and there are three anchoring devices on each tripod, which are respectively located at the corners and two ends of the L-shape. Each anchoring device is connected to the three anchoring devices on the adjacent tripod with an optical fiber. The optical fiber is straightened between the anchoring devices, and each optical fiber is only connected to one or two of the three anchoring devices between different tripods.

[0013] Furthermore, the cross section of the tripod is T-shaped, the cross section of the T is located outside the right angle of the L-shape, and a plurality of assembly holes are provided outside the right angle of the L-shape for fixed connection with the inner wall of the tunnel, and the connection method is expansion screws.

[0014] Furthermore, the anchoring device includes a buckle and an elastic ring, the buckle is a truncated cone-shaped cylindrical structure made of high-toughness plastic, the root diameter of the truncated cone-shaped cylindrical structure is larger than the end diameter, and the end of the truncated cone-shaped cylindrical structure is provided with a groove, the optical fiber passes through the through hole in the middle of the truncated cone-shaped cylindrical structure, and the outer surface of the buckle is provided with a thread;

[0015] The elastic ring is a circular ring structure made of rigid material, and a thread is arranged on the inner surface of the circular ring structure, and the thread matches with the outer surface of the buckle.

[0016] Furthermore, the optical fiber monitor is an optical fiber strain monitoring device integrating an optical fiber strain analyzer and a portable computer.

[0017] According to another aspect of the present invention, a monitoring method of a three-dimensional displacement monitoring device for a tunnel structure is provided, characterized in that it comprises the following steps:

[0018] The tripods are installed at intervals on the inner wall of the tunnel, and the tunnel section is scanned using a 3D laser scanner to determine the initial distance between the anchoring devices on each tripod;

[0019] Passing the optical fiber from the anchoring position through the tripod, wherein each anchoring position passes through three optical fibers and connects three anchoring devices of the adjacent tripod;

[0020] The optical fiber is tensioned to apply a prestress F to the optical fiber;

[0021] Connect one end of the optical fiber to the optical fiber monitor to obtain the strain value at each point along the optical fiber;

[0022] The strain values ​​of the optical fibers are processed to calculate the lengths of the three optical fibers at each anchoring position of each tripod after strain;

[0023] According to the lengths of the three optical fibers at each anchoring position of each tripod after being strained, the coordinate values ​​of each anchoring position of each tripod are calculated;

[0024] By comparing the changes in the coordinate values ​​of the anchoring position of each tripod over time, the translation and rotation of the tripod position in space are obtained, and the three-dimensional displacement of the tunnel structure is monitored.

[0025] Furthermore, the calculation method of the prestress F is:

[0026]

[0027] Wherein, l is the distance between two adjacent tripod anchoring devices, x is the displacement limit of the tunnel structure within this distance, E is the elastic modulus of the optical fiber, and S is the cross-sectional area of ​​the optical fiber.

[0028] Furthermore, the value of l is 5-15m.

[0029] Furthermore, the lengths l of the three optical fibers after strain ′ 1 , l ′ 2 , l ′ 3 They are:

[0030] l ′ 1 = l 1 +l 1 ·Δσ 1

[0031] l ′ 2 = l2 +l 2 ·Δσ 2

[0032] l ′ 3 = l 3 +l 3 ·Δσ 3

[0033] Among them, l 1 , l 2 , l 3 are the initial lengths of the three optical fibers, Δσ 1 , Δσ 2 , Δσ 3 are the strain changes of the three optical fibers respectively.

[0034] Furthermore, the coordinate value (x0, y0, z0) of the anchor position to be calculated is calculated as follows:

[0035]

[0036] Among them, (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3) respectively constitute the coordinate values ​​of the three anchor positions on the tripod before the tripod where the anchor position to be calculated is located.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The present invention realizes three-dimensional displacement monitoring of the tunnel structure by means of a tripod and an optical fiber monitor fixed on the inner wall of the tunnel. An anchoring device is provided on the tripod, and the optical fiber passes through the anchoring device and is connected to the optical fiber monitor. The optical fiber is connected between multiple tripods in a certain pattern, so as to realize three-dimensional displacement monitoring of the tunnel structure. The distributed optical fiber sensing technology has the beneficial effects of long monitoring distance and interference resistance. At the same time, the constructed monitoring system has good flexibility and can adapt to the working conditions of curved tunnels.

[0039] 2. The anchoring device of the present invention is composed of a buckle and an elastic ring. The buckle is a truncated cone-shaped cylindrical structure of high-toughness plastic, with threads engraved on the outer surface and a groove along the axial direction. The elastic ring is a rigid circular ring with internal threads, which can be screwed in and out on the buckle. When the optical fiber passes through the buckle, the elastic ring is tightened downward, squeezing the buckle inward, thereby forming an extrusion force on the optical fiber. The structure is simple and the anchoring effect is good.

[0040] 3. The monitoring method proposed in the present invention obtains the strain change of the optical fiber connected and arranged in a certain pattern through the optical fiber monitor, and uses the optical fiber strain change to calculate the displacement of the tripod through which the optical fiber passes, and then obtains the displacement of the tunnel. All data processing algorithms are integrated in the optical fiber monitor, and the strain information of the optical fiber is converted into the coordinate information of the tripod, so as to realize the three-dimensional displacement monitoring of the tunnel structure, and the data collection is convenient. After installation, the optical fiber monitor continuously and automatically collects data, which can realize all-weather and all-time continuous monitoring, saving time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is an overall schematic diagram of the present invention;

[0042] Figure 2 This is a schematic diagram of the tripod structure;

[0043] Figure 3 is a schematic diagram of the structure of the anchoring device;

[0044] Figure 4 It is a schematic diagram of the geometric model of the present invention;

[0045] In the figure, 1, a tripod, 2, a fiber optic monitor, 11, an assembly hole, 12, an anchoring device, 121 a buckle, and 122, an elastic ring. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0047] The present invention relates to a three-dimensional displacement monitoring device for a tunnel structure, which is composed of a series of tripods 1 and an optical fiber monitor 2. Figure 1 As shown. The main body of the tripod 1 is a T-shaped steel bent at a right angle in an L shape, with the horizontal side of the T located outside the right angle of the L shape. The flange of the vertical side of the tripod 1, i.e., the horizontal side of the T shape, is provided with a plurality of assembly holes 11, preferably four, so as to facilitate the use of expansion screws to fix the tripod 1 on the inner wall of the tunnel. There are a plurality of anchoring devices 12 on the web of the tripod 1, preferably three, and the three anchoring devices 12 form a right triangle when connected in pairs, as shown in FIG. Figure 2 The anchoring device 12 is composed of a buckle 121 and an elastic ring 122. The buckle 121 is made of a high-toughness plastic that is easy to deform elastically. It is a truncated cone-shaped cylindrical structure with a through hole in the middle. The outer surface is engraved with threads. There are three grooves along the axial direction to divide the upper part of the buckle 121. The elastic ring 122 is a relatively rigid ring with threads inside, which can be screwed in and out on the buckle. Figure 3 When the optical fiber passes through the through hole of the buckle 121, the elastic ring 122 is tightened downward, squeezing the buckle 121 inwardly to form a squeezing force to achieve an anchoring effect on the optical fiber.

[0048] The optical fiber monitor 2 integrates an optical fiber strain analyzer and a portable computer. When one end of the optical fiber is connected to the instrument, the strain of the optical fiber can be monitored and the displacement changes of each tripod can be calculated accordingly, thereby reflecting the three-dimensional displacement of the tunnel structure.

[0049] The present invention also relates to a method for monitoring the three-dimensional displacement of a tunnel structure, the steps of which include: installing tripods 1 at intervals on the inner wall of a tunnel, scanning the tunnel section with a three-dimensional laser scanner, and determining the initial distance between the anchoring devices 12 on each tripod 1; passing an optical fiber through the tripod 1 from an anchoring position 12, wherein each anchoring position 12 passes through three optical fibers; tensioning the optical fiber with a tensioning jack to apply a prestress F to the optical fiber; connecting one end of the optical fiber to an optical fiber monitor 2 to obtain strain values ​​at various points along the optical fiber; processing the strain values ​​of the optical fiber to calculate the lengths of the three optical fibers at each anchoring position 12 of each tripod 1 after strain; calculating the coordinate values ​​of each anchoring position 12 of each tripod 1 according to the lengths of the three optical fibers at each anchoring position 12 of each tripod 1 after strain; comparing the coordinate value changes of the anchoring position 12 of each tripod 1 over time, obtaining the translation and rotation conditions of the tripod position in space, and monitoring the three-dimensional displacement of the tunnel structure.

[0050] In engineering applications, the tripod 1 is first fixed in the tunnel using the assembly holes 11 for easy installation without affecting the position of other projects. A tripod is installed every 5-10m. After the tripod is installed, a 3D laser scanner is used to scan the tunnel section to determine the initial distance between the anchoring devices 12 on each tripod 1.

[0051] After positioning the anchoring device 12, the optical fiber is tensioned between the tripods 1. For the entire monitoring system, the three anchoring devices of the tripod 1 are recorded as A, B, and C, and the paths of the nine optical fibers in a series of tripods are: AAA-…, BBB-…, CCC-…, ABA-…, BAB-…, ACA-…, CAC-…, BCB-…, CBC-…. After the optical fiber has passed through, it is tensioned using a tensioning jack to provide a certain prestress F for the optical fiber to ensure that the optical fiber always has a certain initial strain before the pipe segment produces the limit displacement. The value of the prestress can be preliminarily inferred based on the distance l between the two adjacent tripod anchoring devices, the displacement limit value x of the tunnel structure within the designed distance, the elastic modulus E of the optical fiber used, and the cross-sectional area S. The simplified calculation formula is:

[0052]

[0053] After the optical fiber is tensioned, one end of the optical fiber is connected to the optical fiber monitor 2 to obtain the strain value of each point along the optical fiber and perform data processing.

[0054] Take two adjacent tripods as an example to explain the data processing process:

[0055] like Figure 4 As shown, point a 1 、a 2 、a 3 are three anchor points on a known tripod (denoted as #1), whose coordinates are known and are set as (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3); ​​b 1 is the anchor point to be measured on another tripod (denoted as #2), and its coordinates are (x0, y0, z0); the initial lengths of the three optical fibers between the anchor points are l 1 , l 2 , l 3 .

[0056] After the displacement of tripod #2, the strains of the three optical fibers change accordingly. Suppose the changes in strain are Δσ 1 , Δσ 2 , Δσ 3 , and its value can be obtained by monitoring the optical fiber monitor 2.

[0057] From this, we can know that after the displacement of tripod #2, the lengths of the three optical fibers l ′ 1 , l ′ 2 , l ′ 3 They are:

[0058] l ′ 1 = l 1 +l 1 ·Δσ 1

[0059] l ′ 2 = l 2 +l 2 ·Δσ 2

[0060] l ′ 3 = l 3 +l 3 ·Δσ 3

[0061] According to the known 1 1 , l ′2 , l ′ 3 ,have:

[0062]

[0063] By solving the system of equations, we can obtain the coordinates (x0, y0, z0) of the anchor point b_1.

[0064] Similarly, the anchor point b can be obtained 2 、b 3 The coordinate value of tripod #2 is then determined.

[0065] Similarly, according to the known coordinate values ​​of the three anchor points of tripod #2 and the strain variation of the optical fiber, the coordinate values ​​of the three anchor points of tripod #3 can be obtained, and the coordinate values ​​of the three anchor points of all tripods can be obtained by analogy.

[0066] The data processing algorithm is integrated in the optical fiber monitor 2, which monitors the strain of the optical fiber in real time and simultaneously converts the strain data into coordinate data of the three anchor points of the tripod.

[0067] By comparing the changes in the coordinates of the anchor points of the same tripod over time, the translation and rotation of the tripod's position in space can be known, thereby enabling the monitoring of the three-dimensional displacement of the tunnel structure. If combined with 3D modeling software, a 3D displacement model of the tunnel structure can be intuitively constructed.

[0068] The specific implementation of the present invention is described below by means of an embodiment.

[0069] The present invention provides a three-dimensional displacement monitoring device and method for a tunnel structure, which can detect the displacement of the tunnel structure in three-dimensional space.

[0070] Distributed fiber optic sensing technology is a sensing technology that uses optical fiber as a sensing sensitive element and a signal transmission medium. This technology can accurately measure the strain at any point along the optical fiber from one end of the optical fiber. It has the advantages of long distance, high durability, anti-interference, and good flexibility, and is very suitable for tunnel monitoring.

[0071] This embodiment is implemented by a certain method, using nine optical fibers to form a three-dimensional network, and converting the strain measured by the optical fibers into displacement changes of the measuring points, thereby realizing the monitoring of the three-dimensional displacement of the tunnel structure.

[0072] In this embodiment, displacement monitoring is performed on a pipe jacking tunnel.

[0073] When installing the equipment, a tripod 1 is installed on the side of the tunnel segment every 10 meters. After installation, the initial distance between the tripods 1 is measured and recorded by using a 3D laser scanner as the main method and a traditional tape measure as the auxiliary method.

[0074] The optical fiber is then tensioned between the anchoring devices 12. Referring to the above formula, for an elastic modulus of 70 GPa and a cross-sectional area of ​​1.5 mm 2 The acceptable segment displacement of the tunnel is 50 mm, and the required tension force is about 525 N. All optical fibers are tensioned to the set value using tensioning jacks.

[0075] After tensioning is completed, the optical fiber is connected to the optical fiber detector 2, which can continuously collect optical fiber strain and calculate the coordinate data of the tripod anchor point. The coordinate changes of the tripod anchor point can intuitively reflect the displacement changes of the segment such as translation and rotation. The staff can collect monitoring data on-site from the optical fiber detector, and if combined with wireless transmission technologies such as 4G / 5G, the monitoring data can be obtained remotely.

[0076] Preferably, the tripod 1 does not have to be installed separately, but can also be integrated with other tunnel facilities such as cable brackets, so as to further simplify the installation steps and save tunnel space.

[0077] Preferably, the calculation of optical fiber tensile stress in this article is only a simplified method, and it can also be determined by other methods such as empirical formulas in engineering applications.

[0078] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A three-dimensional displacement monitoring device for a tunnel structure, characterized in that: The invention comprises a tripod (1) and an optical fiber monitor (2), wherein the tripod (1) is provided in a plurality and fixedly installed at intervals on the inner wall of a tunnel, each tripod (1) is provided with an anchoring device (12), an optical fiber is connected between two adjacent tripods (1) via the anchoring device (12), the end of the optical fiber is connected to the optical fiber monitor (2), and the optical fiber monitor (2) is an optical fiber strain monitoring device.

2. A three-dimensional displacement monitoring device for a tunnel structure according to claim 1, characterized in that: The tripod (1) is L-shaped, and each tripod (1) has three anchoring devices (12) located at the corners and two ends of the L-shape, respectively; each anchoring device (12) is connected to three anchoring devices (12) on adjacent tripods (1) by optical fibers; the optical fibers are in a straightened state between the anchoring devices (12), and each optical fiber is connected to only one or two of the three anchoring devices (12) between different tripods (1).

3. A three-dimensional displacement monitoring device for a tunnel structure according to claim 2, characterized in that: The cross section of the tripod (1) is T-shaped, the cross section of the T-shape is located outside the right angle of the L-shape, and the right angle of the L-shape is provided with a plurality of assembly holes (11) for fixed connection with the inner wall of the tunnel, and the connection method is expansion screws.

4. The three-dimensional displacement monitoring device for a tunnel structure according to claim 1, characterized in that: The anchoring device (12) comprises a buckle (121) and an elastic ring (122); the buckle (121) is a truncated cone-shaped cylindrical structure made of high-toughness plastic; the root diameter of the truncated cone-shaped cylindrical structure is larger than the end diameter; the end of the truncated cone-shaped cylindrical structure is provided with a groove; the optical fiber passes through a through hole in the middle of the truncated cone-shaped cylindrical structure; and the outer surface of the buckle (121) is provided with a thread; The elastic ring (122) is a circular ring structure made of a rigid material, and a thread is provided on the inner surface of the circular ring structure, and the thread matches the outer surface of the buckle (121).

5. The three-dimensional displacement monitoring device for a tunnel structure according to claim 1, characterized in that: The optical fiber monitor (2) is an optical fiber strain monitoring device that integrates an optical fiber strain analyzer and a portable computer.

6. A monitoring method for a tunnel structure three-dimensional displacement monitoring device according to claims 1-5, characterized in that: The following steps are involved: The tripods (1) are installed at intervals on the inner wall of the tunnel, and the tunnel section is scanned using a three-dimensional laser scanner to determine the initial distance between the anchoring devices (12) on each tripod (1); Passing the optical fiber from the anchoring position (12) through the tripod (1), wherein each anchoring position (12) passes through three optical fibers and connects three anchoring devices (12) of adjacent tripods (1); The optical fiber is tensioned to apply a prestress F to the optical fiber; Connect one end of the optical fiber to an optical fiber monitor (2) to obtain strain values ​​at various points along the optical fiber; The strain value of the optical fiber is processed to calculate the length of three optical fibers at each anchoring position (12) of each tripod (1) after the strain occurs; Calculate the coordinate value of each anchoring position (12) of each tripod (1) according to the length of three optical fibers at each anchoring position (12) of each tripod (1) after strain; By comparing the changes in the coordinate values ​​of the anchoring position (12) of each tripod (1) over time, the translation and rotation of the position of the tripod in space are obtained, and the three-dimensional displacement of the tunnel structure is monitored.

7. The monitoring method according to claim 6, characterized in that: The calculation method of the prestress F is: Wherein, l is the distance between two adjacent tripod anchoring devices, x is the displacement limit of the tunnel structure within this distance, E is the elastic modulus of the optical fiber, and S is the cross-sectional area of ​​the optical fiber.

8. The monitoring method according to claim 7, characterized in that: The value of l is 5-15m.

9. The monitoring method according to claim 6, characterized in that: The lengths l of the three optical fibers after strain ′ 1. l ′ 2. l ′ 3 are: l ′ 1=l1+l1·Δσ1 l ′ 2=l2+l2·Δσ2 l ′ 3=l3+l3·Δσ3 Among them, l1, l2, and l3 are the initial lengths of the three optical fibers, and Δσ1, Δσ2, and Δσ3 are the changes in strain of the three optical fibers.

10. The monitoring method according to claim 6, characterized in that: The calculation method of the coordinate value (x0, y0, z0) of the anchor position (12) to be calculated is: Among them, (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3) respectively constitute the coordinate values ​​of the three anchor positions (12) on the tripod (1) before the tripod (1) where the anchor position (12) to be calculated is located.

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