A fiber optic measurement tube assembly and fiber optic sensing monitoring system

Abstract

The utility model relates to geotechnical engineering monitoring technical field discloses a kind of optical fiber measuring tube assembly and optical fiber sensing monitoring system, including measuring tube body;Longitudinal cable, with the outer wall coupling of the measuring tube body, and extend in parallel to the axial direction of the measuring tube body;Spiral cable, with the outer wall coupling of the measuring tube body, and spiral shape extends according to preset spiral angle along the axial direction of the measuring tube body.The utility model carries out strain monitoring using the combination of longitudinal cable and spiral cable, and longitudinal cable and spiral cable are different in layout mode, beneficial to collect more comprehensive strain data, and measuring tube body gives consideration to structural strength and flexibility, both ensure stability, and can be deformed with geotechnical body, more beneficial to longitudinal cable and spiral cable and geotechnical body collaborative deformation, improve measurement accuracy.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering monitoring technology, specifically to an optical fiber measuring tube assembly and an optical fiber sensing monitoring system. Background Technology

[0002] In the field of geotechnical engineering, accurate monitoring of the sliding of underground rock and soil masses is crucial. This not only relates to the safety and stability of the project but also provides key information for disaster early warning and project maintenance. Inclined tubes, as a widely used monitoring tool, play an irreplaceable role in identifying the location of shear zones and sliding surfaces in slopes and embankments, as well as monitoring the magnitude of deformation. Fiber optic inclinometers (also known as fiber optic measurement tube assemblies) based on fiber optic sensing monitoring systems are currently widely used. They monitor the condition of soil and rock structures by demodulating the fiber strain on the fiber optic inclinometer through the fiber optic sensing monitoring system. Among them, Chinese patent application number 202411273524.8 provides a high-sensitivity fiber optic shape sensor, measuring device, and method for identifying torsion direction. This can be applied to fields such as intraoperative navigation in medical endoscopy, shape monitoring and navigation of interventional surgical catheters, attitude tracking and control of aircraft and intelligent robots, and deformation monitoring of soil and rock structures.

[0003] However, fiber optic inclinometers still have many problems in geotechnical engineering monitoring applications. These mainly include: 1. The technical solution in Chinese patent application number 202411273524.8 uses flexible materials to encapsulate single-mode and multi-core optical fibers. This flexible encapsulation structure may cause self-deformation in geotechnical environments, and it lacks a dedicated matrix structure for coupling with the soil mass, potentially affecting the accurate measurement of soil structure deformation. 2. Fiber optic inclinometers used for geotechnical structure measurement require sufficient length for deep measurements. This is typically achieved by splicing multiple tubes, but excessive localized stress at the splicing points can easily lead to fiber damage. Utility Model Content

[0004] The purpose of this invention is to provide an optical fiber measuring tube assembly and an optical fiber sensing and monitoring system, so as to solve at least one of the above-mentioned problems.

[0005] To address the aforementioned technical problems, the first aspect of this application provides an optical fiber measuring tube assembly for monitoring the condition of geotechnical engineering structures, the optical fiber measuring tube assembly comprising: Measuring tube body; A longitudinal optical cable is coupled to the outer wall of the measuring tube body and extends in an axial direction parallel to the measuring tube body; The spiral optical cable is coupled to the outer wall of the measuring tube body and extends in a spiral shape along the axial direction of the measuring tube body at a preset spiral angle.

[0006] In some embodiments, the measuring tube body includes: At least two sections of pipe are spliced ​​together; and The baseband is laid on the outer wall of the splice between two adjacent tubes, and the longitudinal optical cable and the spiral optical cable cross the splice from the outer surface of the baseband.

[0007] In some embodiments, the baseband includes: Upper arc-shaped piece; and The lower arc-shaped piece, the upper arc-shaped piece, and the lower arc-shaped piece are respectively attached to the outer surfaces of two adjacent tubes and cover the joint of the two adjacent tubes.

[0008] In some embodiments, the measuring tube body further includes: An internal connector, one end of which is inserted into the end of one of two adjacent pipe sections, and the other end of which is inserted into the end of the other of two adjacent pipe sections, to connect the two adjacent pipe sections; Multiple rivets are used to fix the insert-type connector to each of the tubes.

[0009] In some embodiments, the rivets are spaced apart from the longitudinal optical cable and the spiral optical cable; and / or, the baseband is riveted to two adjacent sections of the tube body by the rivets; and / or, the baseband is coupled to the tube body; and / or, both the longitudinal optical cable and the spiral optical cable are coupled to the measuring tube body by structural adhesive.

[0010] In some embodiments, the at least two spliced ​​pipe sections include an upper inclinometer pipe and a lower inclinometer pipe, with a splice seam formed at the joint of the upper and lower inclinometer pipes, and the base tape is laid at the splice seam with the center of the base tape aligned with the splice seam; and / or, the pipe body is made of aluminum alloy, with an outer diameter of 64 mm, a wall thickness of 2 mm, and the length of each pipe section is 3 m.

[0011] In some embodiments, the measuring tube body includes at least two segments spliced ​​together; and / or, the fiber optic measuring tube assembly includes three segments of the longitudinal optical cable, the three segments of the longitudinal optical cable being arrayed along the circumferential direction of the measuring tube body at positions of 0°, 120°, and 240° of the measuring tube body; and / or, the outer wall of the measuring tube body has a groove extending along the axial direction of the measuring tube body, and the longitudinal optical cable is embedded in the groove.

[0012] In some embodiments, a guide line is provided on the measuring tube body, and the guide line is spirally arranged on the measuring tube body according to the preset spiral angle, and the position of the spiral optical cable corresponds to the guide line.

[0013] In some embodiments, the longitudinal optical cable and the spiral optical cable are connected in series to form a single optical cable; and / or, the preset spiral angle is between 10° and 70°.

[0014] A second aspect of this application provides a fiber optic sensing and monitoring system, comprising: The fiber optic measurement tube assembly described in any of the above embodiments; A fiber optic sensor demodulator is connected to the longitudinal optical cable and the spiral optical cable, and the fiber optic sensor demodulator is configured to monitor bending strain and torsional strain through the longitudinal optical cable and the spiral optical cable.

[0015] Compared with the prior art, the beneficial effects of this utility model are: 1. By simultaneously coupling longitudinal and spiral optical cables onto the measuring tube body, the longitudinal and spiral optical cables undergo strain along with the measuring tube body. Strain monitoring can be performed using the combination of longitudinal and spiral optical cables. The different deployment methods of the longitudinal and spiral optical cables facilitate the acquisition of more comprehensive strain data. The measuring tube body balances structural strength and flexibility, ensuring its own stability while also deforming in tandem with the soil and rock mass. This further facilitates the coordinated deformation of the longitudinal and spiral optical cables with the soil and rock mass, improving measurement accuracy.

[0016] 2. A baseband is laid on the outer wall of the splice of two adjacent tubes. The longitudinal optical cable and the spiral optical cable cross the splice from the outer surface of the baseband. The baseband converts the local concentrated strain into measurable regional strain, avoiding the problem of damage to the longitudinal optical cable and the spiral optical cable due to local stress concentration when passing through the splice, and ensuring the continuity of strain transmission when crossing the splice.

[0017] 3. Two adjacent pipe sections are fixed together using an internal connector and rivets, and a base tape is laid at the joint. The internal connector and rivets fix the two adjacent pipe sections together, resulting in a stable and reliable splicing, a simple structure, and low cost; the internal connector makes the splicing of the two adjacent pipe sections more reliable and stable.

[0018] 4. The baseband consists of two individual units: an upper arc-shaped piece and a lower arc-shaped piece. The upper and lower arc-shaped pieces are assembled separately for easy assembly.

[0019] 5. A single rivet can simultaneously secure the baseband, tube body, and internal connector, making full use of the fastening function of a single rivet and reducing the amount of fastening work.

[0020] 6. The three longitudinal optical cables are arrayed along the circumference of the measuring tube body at positions of 0°, 120°, and 240° on the measuring tube body, which can better monitor the bending direction of the measuring tube body.

[0021] 7. Longitudinal optical cables and spiral optical cables are connected in series to form a single optical cable. A single optical cable can reduce the number of optical cables and components, resulting in higher integration. Attached Figure Description

[0022] Figure 1 A schematic diagram of the overall structure of the fiber optic measurement tube assembly provided for an embodiment of this utility model; Figure 2 A perspective view of the baseband region provided for an embodiment of this utility model; Figure 3 A schematic diagram of the baseband structure provided for an embodiment of this utility model; Figure 4 For along Figure 1 A schematic diagram of the cross-sectional structure of AA; Figure 5 For along Figure 1 Schematic diagram of the cross-sectional structure of BB; Figure 6 A schematic diagram illustrating the use of the fiber optic sensing and monitoring system provided for an embodiment of this utility model.

[0023] In the diagram: 1. Upper section inclinometer tube; 2. Lower section inclinometer tube; 3. Joint; 4. Rivet; 5. Baseband; 51. Upper arc-shaped plate; 52. Lower arc-shaped plate; 53. Guide line; 6. Longitudinal optical cable; 7. Spiral optical cable; 8. Groove; 9. Internal connector; 10. Optical cable protection box at the top of the borehole; 11. Brillouin demodulator; 12. Slope monitoring PC platform end; 13. Communication optical cable. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figures 1-5 This application provides an optical fiber measurement tube assembly through its embodiments. Furthermore, references... Figure 6 This application also provides an optical fiber sensing monitoring system, which includes an optical fiber sensing demodulator and the aforementioned optical fiber measuring tube assembly. The optical fiber sensing demodulator is connected to a longitudinal optical cable 6 and a spiral optical cable 7. The optical fiber sensing demodulator is configured to monitor the strain of geotechnical engineering structures via the longitudinal optical cable 6 and the spiral optical cable 7. Existing optical fiber sensing demodulators can be used, such as a Brillouin demodulator 11, which will not be elaborated upon further. (Explanatory) Figure 4 and Figure 5 This is a cross-sectional schematic diagram. Figure 4 and Figure 5 The spiral optical cable 7 is not shown in any of the diagrams. (Reference) Figure 1 and Figure 6 The spiral optical cable 7 extends in a spiral shape along the axial direction of the measuring tube body at a preset spiral angle.

[0026] The fiber optic measurement tube assembly provided in the embodiments of this application is described in detail below.

[0027] refer to Figure 1-5 In some embodiments, the fiber optic measuring tube assembly includes a measuring tube body, a longitudinal optical cable 6, and a spiral optical cable 7. The longitudinal optical cable 6 is coupled to the outer wall of the measuring tube body and extends in a direction parallel to the axial direction of the measuring tube body. The spiral optical cable 7 is coupled to the outer wall of the measuring tube body and extends spirally along the axial direction of the measuring tube body at a preset spiral angle. The embodiments of this application couple the longitudinal optical cable 6 and the spiral optical cable 7 onto the measuring tube body. The longitudinal optical cable 6 and the spiral optical cable 7 undergo strain along with the measuring tube body, respectively, and the combination of the longitudinal optical cable and the spiral optical cable is used for monitoring the deformation of soil and rock structures. The different layout methods of the longitudinal optical cable 6 and the spiral optical cable 7 facilitate the acquisition of more comprehensive strain data. The measuring tube body balances structural strength and flexibility, ensuring its own stability while deforming in tandem with the soil and rock mass, which further facilitates the coordinated deformation of the longitudinal optical cable 6 and the spiral optical cable 7 with the soil and rock mass, improving measurement accuracy.

[0028] Explained, coupling refers to the fixation of the longitudinal optical cable 6 and the spiral optical cable 7 to the measuring tube body through bonding, adhesive, or other means, so that the longitudinal optical cable 6 and the spiral optical cable 7 can deform synchronously with the measuring tube body. The preset helix angle is between 10° and 70°. Preferably, it is between 20° and 60°, for example, it can be 30°, 40°, 45°, or 60°, etc.

[0029] In some embodiments, the measuring tube body includes at least two segments joined together, which can extend the length of the measuring tube body.

[0030] refer to Figure 1 In some embodiments, the measuring tube body includes at least two spliced ​​tube sections and a baseband 5. The baseband 5 is laid on the outer wall of the splice between adjacent tube sections, and the longitudinal optical cable 6 and the spiral optical cable 7 cross the splice from the outer surface of the baseband 5. The baseband 5 can be made of steel, an alloy, or aluminum, with steel being preferred. The baseband 5 converts the localized strain concentration at the splice into measurable regional strain, avoiding damage to the longitudinal optical cable 6 and the spiral optical cable 7 due to localized stress concentration at the splice, and ensuring the continuity of strain transmission when the longitudinal optical cable 6 and the spiral optical cable 7 cross the splice. The baseband 5 can be made of aluminum alloy or steel.

[0031] refer to Figures 1-3 In some embodiments, the baseband 5 includes an upper arc-shaped piece 51 and a lower arc-shaped piece 52, which are respectively attached to the outer surfaces of two adjacent tubes and cover the joint between the two adjacent tubes. The baseband 5 consists of two individual units, the upper arc-shaped piece 51 and the lower arc-shaped piece 52, which are assembled separately for easy assembly.

[0032] refer to Figures 1-3 In some embodiments, a guide line 53 is provided on the measuring tube body; specifically, the guide line 53 is provided on the tube body and / or the upper arc-shaped piece 51 and / or the lower arc-shaped piece 52, and the guide line 53 is spirally arranged on the tube body and / or the baseband according to a preset spiral angle; the position of the spiral optical cable 7 corresponds to the guide line 53. The guide line 53 serves to guide the spiral optical cable 7 to spirally coil according to the preset spiral angle. The guide line 53 can be a marking line, groove, or other structure.

[0033] In some implementations, the preset helix angle is between 10° and 70°. Preferably, it can be one of 30°, 45°, or 60°.

[0034] refer to Figures 1-5 In some embodiments, the fiber optic measurement tube assembly further includes an insert connector 9 and multiple rivets 4. One end of the insert connector 9 is inserted into the end of one of the two adjacent tube sections, and the other end of the insert connector 9 is inserted into the end of the other of the two adjacent tube sections to connect the two adjacent tube sections; the insert connector 9 is fixedly connected to each tube section by the rivets 4. Further, in some embodiments, the rivets 4 are spaced apart from the longitudinal optical cable 6 and the spiral optical cable 7 to avoid interference between the rivets 4 and the longitudinal optical cable 6 and the spiral optical cable 7. The insert connector 9, in conjunction with the rivets 4, fixes the two adjacent tube sections, resulting in a stable and reliable splicing, a simple structure, and low cost; the insert connector 9 makes the splicing reliability of the two adjacent tube sections higher and more stable.

[0035] refer to Figures 1-5 In some embodiments, the baseband 5 is riveted to two adjacent pipe sections by rivets 4. One rivet 4 can simultaneously fix the baseband 5, the pipe, and the internal connector 9, making full use of the fastening function of a single rivet 4 and reducing the amount of fastening work. Furthermore, structural adhesive can be used to couple the baseband 5 with the pipe to improve the coupling, so that the baseband 5 deforms along with the pipe.

[0036] refer to Figures 1-5In some embodiments, both the longitudinal optical cable 6 and the spiral optical cable 7 are coupled to the measuring tube body via structural adhesive. Specifically, the longitudinal optical cable 6 and the spiral optical cable 7 are coupled to the tube body and the baseband 5, respectively. At the splice of two adjacent tube sections, the baseband 5 is coupled to the tube body, and the longitudinal optical cable 6 and the spiral optical cable 7 are coupled to the baseband 5, thus allowing the three to couple with each other.

[0037] refer to Figures 1-3 In some embodiments, at least two sections of pipe are spliced ​​together, including an upper section of inclinometer 1 and a lower section of inclinometer 2. A splice seam 3 is formed at the splice joint of the upper section of inclinometer 1 and the lower section of inclinometer 2. A base strip 5 is laid at the splice seam 3, and the center of the base strip 5 is aligned with the splice seam 3.

[0038] Specifically, the tube body is defined as including the upper inclinometer tube 1 and the lower inclinometer tube 2, with a splice seam 3 formed at the joint. The baseband 5 precisely covers the seam to ensure that the spiral optical cable 7 can effectively transmit strain when crossing the seam, avoiding monitoring failure caused by stress concentration at the seam.

[0039] refer to Figures 1-3 In some embodiments, the tube body can be made of aluminum alloy with an outer diameter of 64mm and a wall thickness of 2mm. Each section of the tube body is 3m long. Its structural strength, weight and length are appropriate, which can meet the usage requirements, facilitate processing and manufacturing, and reduce costs.

[0040] refer to Figures 1-5 In some embodiments, the fiber optic measurement tube assembly includes three longitudinal optical cables 6, which are arrayed along the circumference of the measurement tube body at positions of 0°, 120°, and 240°. This allows for direct sensing of the strain caused by bending and axial deformation of the tube body, and better monitoring of the bending direction of the measurement tube body.

[0041] refer to Figures 1-5 In some embodiments, the outer wall of the measuring tube body is provided with a groove 8 extending along the axial direction of the measuring tube body, and the longitudinal optical cable 6 is embedded in the groove 8.

[0042] Specifically, the groove 8 on the outer wall of the measuring tube provides a fixed path for the longitudinal optical cable 6, ensuring that the three longitudinal optical cable segments 6 are strictly arranged along the 0°, 120°, and 240° positions, so that the calculated direction and magnitude of the bending strain conform to the theoretical model. The shape of the groove 8 can be V-shaped or U-shaped, with V-shaped being preferred.

[0043] refer to Figures 1-5 In some implementations, the longitudinal optical cable 6 and the spiral optical cable 7 are connected in series to form a single optical cable. A single optical cable reduces the number of optical cables, the number of components, and the level of integration.

[0044] For details, please refer to Figure 5Three longitudinal optical cables 6 are arrayed along the circumference of the measuring tube body at positions of 0°, 120°, and 240°. A spiral optical cable 7 extends spirally along the axial direction of the measuring tube body at a preset spiral angle. At the bottom of the measuring tube body, two of the three longitudinal optical cables 6 are fused together in series to form a U-shaped series connection. The bottom of the third longitudinal optical cable 6 is fused together with the bottom of the spiral optical cable 7 to form a U-shaped series connection. At the top of the measuring tube body, the top of the third longitudinal optical cable 6 is fused together with the top of one of the other two longitudinal optical cables 6 to form a U-shaped series connection. The top of the other longitudinal optical cable 6 is connected to the Brillouin demodulator 11. The top of the spiral optical cable 7 is connected to the Brillouin demodulator 11.

[0045] It should be noted that the Brillouin demodulator 11 is connected in series with the slope monitoring PC platform 12 and the top optical cable protection box 10 via the communication optical cable 13.

[0046] refer to Figure 1 In the specific embodiment provided, the measuring tube body consists of at least two tube sections, such as the upper inclinometer tube 1 and the lower inclinometer tube 2, which are spliced ​​together by an internal connector 9, forming a splice seam 3 at the splice point, and fixed by rivets 4. The groove 8 on the outer wall of the tube is V-shaped, which provides a fixing path for the optical cable; the longitudinal optical cable 6 and the spiral optical cable 7 are both fixed to the tube body by structural adhesive. The three longitudinal optical cables 6 are arranged vertically along the axial direction of the tube body, located at 0°, 120°, and 240° of the circumference, respectively, directly sensing the strain generated by the bending and axial deformation of the tube body; the spiral optical cable 7 is spirally arranged along the axial direction of the tube body, and is subjected to the combined effects of bending, axial deformation, and torsional deformation, generating a composite strain. At the splice seam 3 of adjacent tube bodies, a base strip 5 composed of an upper arc-shaped piece 51 and a lower arc-shaped piece 52 is laid. The base strip 5 is pre-bent, and the center of the base strip 5 is aligned with the splice seam 3. The spiral optical cable 7 crosses the splice seam 3 along the etched guide line 53 on the upper arc-shaped plate 51. The baseband 5 converts the concentrated strain at the splice seam 3 into measurable regional strain, preventing damage to the spiral optical cable 7 due to stress concentration at the splice seam 3, while ensuring continuous transmission of torsional deformation signals. In use, strain data of the longitudinal optical cable 6 and spiral optical cable 7 of the fiber optic measuring tube assembly are collected by an optical fiber sensor demodulator, such as a Brillouin demodulator 11, and the effects of different deformations are separated by an algorithm. Existing equipment can be used as the optical fiber sensor demodulator.

[0047] In addition, by utilizing the angular differences of the three longitudinal optical cables 6, the maximum bending strain and direction of the tube cross-section can be calculated, thus eliminating blind spots in single-direction monitoring.

[0048] Furthermore, when the fiber optic sensor demodulator monitors the strain of geotechnical engineering structures through the longitudinal optical cable 6 and the spiral optical cable 7, the specific monitoring and calculation methods can be based on existing methods. The improvement in this application is only in the structural improvement of the fiber optic measuring tube assembly, and does not involve the improvement of the demodulation algorithm of the fiber optic sensor demodulator, so it will not be elaborated further.

[0049] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and detail may be made to the present invention without departing from the spirit and scope of the appended claims.

Claims

1. A fiber optic measuring tube assembly for monitoring the structural condition of geotechnical engineering structures, characterized in that, The fiber optic measurement tube assembly includes: Measuring tube body; A longitudinal optical cable (6) is coupled to the outer wall of the measuring tube body and extends in an axial direction parallel to the measuring tube body; The spiral optical cable (7) is coupled to the outer wall of the measuring tube body and extends in a spiral shape along the axial direction of the measuring tube body at a preset spiral angle.

2. The fiber optic measurement tube assembly as described in claim 1, characterized in that, The measuring tube body includes: At least two sections of pipe are spliced ​​together; and The baseband (5) is laid on the outer wall of the splice of two adjacent tubes, and the longitudinal optical cable (6) and the spiral optical cable (7) cross the splice from the outer surface of the baseband (5).

3. The fiber optic measurement tube assembly as described in claim 2, characterized in that, The baseband (5) includes: Upper arc-shaped piece (51); and The lower arc-shaped piece (52), the upper arc-shaped piece (51) and the lower arc-shaped piece (52) are respectively attached to the outer surface of the two adjacent tubes and cover the joint of the two adjacent tubes.

4. The fiber optic measurement tube assembly as described in claim 2, characterized in that, The measuring tube body also includes: An internal connector (9) is inserted at one end into the end of one of the two adjacent pipe sections and at the other end into the end of the other of the two adjacent pipe sections to connect the two adjacent pipe sections. Multiple rivets (4) are used to fix the insert connector (9) to each of the tube bodies.

5. The fiber optic measurement tube assembly as described in claim 4, characterized in that, The rivets (4) are spaced apart from the longitudinal optical cable (6) and the spiral optical cable (7); and / or, the baseband (5) is riveted to two adjacent sections of the tube body by the rivets (4); and / or, the baseband (5) is coupled to the tube body; and / or, the longitudinal optical cable (6) and the spiral optical cable (7) are both coupled to the measuring tube body by structural adhesive.

6. The fiber optic measurement tube assembly as described in claim 2, characterized in that, The at least two sections of the pipe body are spliced ​​together, including an upper section of inclinometer (1) and a lower section of inclinometer (2). A splice seam (3) is formed at the splice joint of the upper section of inclinometer (1) and the lower section of inclinometer (2). The base strip (5) is laid at the splice seam (3), and the center of the base strip (5) is aligned with the splice seam (3). And / or, the pipe body is made of aluminum alloy, with an outer diameter of 64 mm and a wall thickness of 2 mm. The length of each section of the pipe body is 3 m.

7. The fiber optic measurement tube assembly as described in claim 1, characterized in that, The measuring tube body includes at least two sections of tube body spliced ​​together; and / or, the optical fiber measuring tube assembly includes three sections of the longitudinal optical cable (6), the three sections of the longitudinal optical cable (6) are arrayed along the circumferential direction of the measuring tube body at positions of 0°, 120° and 240° of the measuring tube body; and / or, the outer wall of the measuring tube body is provided with a groove (8) extending along the axial direction of the measuring tube body, and the longitudinal optical cable (6) is embedded in the groove (8).

8. The fiber optic measurement tube assembly as described in claim 1, characterized in that, The measuring tube body is provided with a guide line (53), which is spirally arranged on the measuring tube body according to the preset spiral angle, and the position of the spiral optical cable (7) corresponds to the guide line (53).

9. The fiber optic measurement tube assembly as described in claim 1, characterized in that, The longitudinal optical cable (6) and the spiral optical cable (7) are connected in series to form an optical cable; and / or, the preset spiral angle is between 10° and 70°.

10. A fiber optic sensing and monitoring system, characterized in that, include: The fiber optic measurement tube assembly according to any one of claims 1-9; A fiber optic sensor demodulator is connected to the longitudinal optical cable (6) and the spiral optical cable (7), and the fiber optic sensor demodulator is configured to monitor the strain of geotechnical structures through the longitudinal optical cable (6) and the spiral optical cable (7).

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