Distributed strain sensing optical cable suitable for being directly buried and installed in rock-soil body

Abstract

The utility model relates to a distributed strain sensing optical cable suitable for rock-soil body direct burial installation, which comprises a strain sensing optical unit, a first protection unit and a second protection unit, the strain sensing optical unit comprises a sensing optical fiber, a tightening sleeve and a spiral armor tube, a plurality of continuous bonding points are arranged between the tightening sleeve and the spiral armor tube, and the first protection unit is connected with the second protection unit. The sensing optical fiber is provided with a sensing grating at a part between two adjacent bonding points, the first protection unit is sleeved outside the spiral armor tube, and the second protection unit is sleeved outside the first protection unit; when strain is generated outside the optical cable, the strain drives the sensing optical fiber to be transmitted to the optical gratings from outside to inside through the spiral armored tube, so that the optical cable has the strain measurement capability, the detection range of the plurality of optical gratings is large, the spiral armored tube has relatively high anti-pressure capability, and meanwhile, the strain measurement sensitivity can be improved; the first protection unit and the second protection unit can effectively protect the strain sensing optical unit, so that the optical cable has good mechanical strength.

Description

Technical Field

[0001] The utility model relates to the technical field of distributed strain sensing, in particular to a distributed strain sensing optical cable suitable for direct burial installation in rock and soil bodies. Background Art

[0002] Monitoring the deformation and slippage of rock and soil masses not only helps to improve the safety and reliability of projects, but is also an important means of preventing earthquake disasters and protecting the ecological environment. It is of great significance in engineering, safety and environmental management.

[0003] Existing geotechnical monitoring mostly uses single-point sensors, which require strong professionalism for installation and maintenance and are difficult to carry out under certain geological conditions. Single-point sensors also have a small detection range and provide limited value in geotechnical data. In geotechnical health monitoring applications, strain sensor cables must possess a certain mechanical strength to protect them from damage during installation and long-term use. However, increasing the mechanical strength of the cable reduces the sensitivity of geotechnical strain measurements. Utility Model Content

[0004] In view of this, it is necessary to provide a distributed strain sensing optical cable suitable for direct burial installation in rock and soil to solve the problems of limited detection range of existing single-point sensors and difficulty in ensuring that the strain sensor optical cable has both good mechanical strength and high sensitivity.

[0005] The utility model provides a distributed strain sensing optical cable suitable for direct burial installation in rock and soil, comprising a strain sensing optical unit, a first protective unit, and a second protective unit. The strain sensing optical unit comprises a sensing optical fiber, a tight sleeve, and a spiral armor tube, which are sequentially sleeved from the inside to the outside. A plurality of bonding points arranged along the length direction of the sensing optical fiber are provided between the tight sleeve and the spiral armor tube. A grating is formed on the sensing optical fiber at a portion between two adjacent bonding points. The first protective unit is sleeved outside the spiral armor tube, and the second protective unit is sleeved outside the first protective unit.

[0006] Furthermore, the plurality of bonding points are arranged at equal distances along the length direction of the sensing optical fiber.

[0007] Furthermore, the tightening sleeve and the spiral armor tube are bonded together.

[0008] Furthermore, the first protection unit includes a first protective sleeve sleeved on the spiral armored tube.

[0009] Furthermore, the first protection unit further includes a first reinforcement member, and the first reinforcement member is axially disposed through the first protective sleeve.

[0010] Furthermore, the first reinforcement member is a phosphated steel wire, and there are two first reinforcement members, which are arranged in parallel and opposite to each other on both sides of the sensing optical fiber.

[0011] Furthermore, the second protection unit includes a second protective cover sleeved on the first protection unit.

[0012] Furthermore, the second protection unit further includes a second reinforcement member, and the second reinforcement member is axially disposed through the second protective sleeve.

[0013] Furthermore, the second reinforcement member is a phosphated steel wire, and there are two second reinforcement members, which are arranged in parallel and opposite to each other on both sides of the sensing optical fiber.

[0014] Furthermore, the second protection unit further includes a longitudinal steel strip, which is arranged between the first protection unit and the second protective cover, and the outer wall and the inner wall of the longitudinal steel strip are both formed with embossing.

[0015] Compared with the existing technology, the tight bundle tube layer provides protection for the sensing optical fiber. When strain occurs in any two adjacent bonding points, the strain is transmitted from the outside to the inside through the spiral armor tube driving the sensing optical fiber to the grating, thereby enabling the optical cable to measure strain. Multiple gratings can be arranged at different positions according to actual needs, and the detection range is large. The above-mentioned spiral armor tube has strong compressive resistance. At the same time, due to its spiral structure, it can be stretched and can be restored within a certain deformation range. Both positive and negative strains can be measured. On the above basis, the first protection unit and the second protection unit can effectively protect the strain sensing optical unit, so that the optical cable has good mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of a distributed strain sensing optical cable suitable for direct burial installation in rock and soil provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0017] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0018] like Figure 1As shown, the utility model provides a distributed strain sensing optical cable suitable for direct burial installation in rock and soil, including a strain sensing optical unit 100, a first protective unit 200, and a second protective unit 300. The strain sensing optical unit 100 includes a sensing optical fiber 110, a tightening sleeve 120, and a spiral armor tube 130, which are sequentially arranged from the inside to the outside. There are multiple bonding points arranged along the length direction of the sensing optical fiber 110 between the tightening sleeve 120 and the spiral armor tube 130. The sensing optical fiber 110 has a grating between two adjacent bonding points. The first protective unit 200 is sleeved on the outside of the spiral armor tube 130, and the second protective unit 300 is sleeved on the outside of the first protective unit 200.

[0019] During implementation, the tight bundle tube layer provides protection for the sensing optical fiber 110. When strain occurs between any two adjacent bonding points, the spiral armor tube 130 drives the sensing optical fiber 110 to be transferred to the grating, thereby enabling the optical cable to measure strain. Multiple gratings can be arranged at different positions according to actual needs, with a large detection range. The above-mentioned spiral armor tube 130 has strong compressive resistance. At the same time, due to its spiral structure, it can be stretched and restored within a certain deformation range, which can greatly improve the sensitivity of strain measurement. On this basis, the first protection unit 200 and the second protection unit 300 can effectively protect the strain sensing optical unit 100, so that the optical cable has good mechanical strength.

[0020] The strain sensing optical unit 100 in this embodiment includes a sensing optical fiber 110, a tightening sleeve 120, and a spiral armor tube 130, which are sequentially arranged from the inside to the outside. There are multiple bonding points arranged along the length direction of the sensing optical fiber 110 between the tightening sleeve 120 and the spiral armor tube 130. The sensing optical fiber 110 has a grating formed between two adjacent bonding points.

[0021] Among them, the sensing optical fiber 110 will generate strain when subjected to external force. Through distributed optical fiber demodulation technology, its measurement range is 3% strain, and its geometric size diameter can be selected as 150~250μm, so that the deformation and slip of the rock and soil body can be distributedly measured based on the feedback of the above strain.

[0022] The diameter of the tightening sleeve 120 can be selected from 0.7 to 1.5 mm, and the material can be selected from PVC, hytrel, PA, etc.

[0023] The spiral armor tube 130 can be made of high-quality stainless steel, which has strong compressive resistance. At the same time, due to its spiral structure, it can be stretched and can be restored within a certain deformation range. The size of the spiral armor tube 130 is generally 1.2~5.0mm.

[0024] It is understood that multiple bonding points are equidistantly spaced along the length of the sensing optical fiber 110, and the tight-fitting sleeve 120 and the spiral armor tube 130 are bonded together. Specifically, the spiral armor tube 130 and the tight-fitting sleeve are fixed at intervals L using a high-strength adhesive 340. A grating is located between the two fixing points. When strain occurs within any interval L, the spiral armor tube 130 drives the sensing optical fiber 110 to the grating, thereby enabling the optical cable to measure strain. Compared to other structures, the structure of the spiral armor tube 130 can greatly improve the sensitivity of strain measurement.

[0025] The first protection unit 200 in this embodiment includes a first protective cover 210 sleeved on the spiral armor tube 130. The first protective cover 210 is made of high-density polyethylene material, which is acid-resistant, alkali-resistant, and organic solvent-resistant, and has high surface hardness and tensile strength.

[0026] To further enhance the mechanical strength of the optical cable, in one embodiment, the first protective unit 200 further includes a first reinforcement member 220, which is disposed axially through the first protective sheath 210. The first reinforcement member 220 is a phosphated steel wire. There are two first reinforcement members 220, which are disposed parallel and opposite to each other on either side of the sensing optical fiber 110, primarily ensuring the tensile strength of the optical cable.

[0027] The second protection unit 300 in this embodiment includes a second protection cover 310 sleeved on the first protection unit 200. The second protection cover 310 is made of high-density polyethylene material, which is resistant to acids, alkalis, and organic solvents and has high surface hardness and tensile strength.

[0028] In order to further improve the mechanical strength of the optical cable, in one embodiment, the second protective unit 300 also includes a second reinforcement member 320, which is axially inserted through the second protective cover 310. The second reinforcement member 320 is a phosphated steel wire. There are two second reinforcement members 320. The two second reinforcement members 320 are parallel and oppositely arranged on both sides of the sensing optical fiber 110, which are the main guarantee of the tensile strength of the optical cable.

[0029] In this embodiment, the second protective unit 300 also includes a longitudinal steel band 330, which is positioned between the first protective unit 200 and the second protective cover 310. Both the outer and inner walls of the longitudinal steel band 330 are corrugated. The longitudinal steel band 330 not only further improves the tensile and compressive strengths of the optical cable, but also, because it is corrugated during the optical cable production process, it reduces relative slippage between the first protective cover 210 and the second protective cover 310.

[0030] The first protective cover 210 and the longitudinal steel belt 330 can be connected by a hot melt adhesive 340. Specifically, during the production of the optical cable, the adhesive 340 is heated at a high temperature above 200°C to a molten flow state, and has a high bonding strength after cooling and solidification.

[0031] The first protective cover 210 and the second protective cover 310 are firmly connected together. On the one hand, this provides the optical cable with mechanical strength sufficient for direct burial applications; on the other hand, through structural design and the addition of high-strength adhesive 340, the strain is transferred from the outside to the inside to the strain sensing unit.

[0032] Compared with the existing technology: the tight bundle tube layer provides protection for the sensing optical fiber 110. When strain occurs between any two adjacent bonding points, the spiral armor tube 130 drives the sensing optical fiber 110 to be transferred to the grating, thereby enabling the optical cable to measure strain. Multiple gratings can be arranged at different positions according to actual needs, and the detection range is large. The above-mentioned spiral armor tube 130 has strong compressive resistance. At the same time, due to its spiral structure, it can be stretched and compressed and can recover within a certain deformation range. Both positive and negative strains can be measured. On this basis, the first protection unit 200 and the second protection unit 300 can effectively protect the strain sensing optical unit 100, so that the optical cable has good mechanical strength.

[0033] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in the present invention should be covered by the protection scope of the present invention.

Claims

1. A distributed strain sensing optical cable suitable for direct burial installation in rock and soil, characterized in that: include: A strain sensing optical unit includes a sensing optical fiber, a tight sleeve, and a spiral armor tube, which are sequentially arranged from the inside out. The tight sleeve and the spiral armor tube have multiple bonding points arranged along the length direction of the sensing optical fiber, and the sensing optical fiber has a grating between two adjacent bonding points. A first protective unit, which is sleeved outside the spiral armored tube; The second protection unit is sleeved outside the first protection unit.

2. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 1, characterized in that: The plurality of bonding points are arranged at equal distances along the length direction of the sensing optical fiber.

3. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 1, characterized in that: The tightening sleeve and the spiral armor tube are bonded together.

4. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 1, characterized in that: The first protection unit includes a first protective sleeve sleeved on the spiral armored tube.

5. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 4, characterized in that: The first protection unit further includes a first reinforcement member, which is axially disposed through the first protective sleeve.

6. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 5, characterized in that: The first reinforcement member is a phosphating steel wire. There are two first reinforcement members, and the two first reinforcement members are arranged in parallel and opposite to each other on both sides of the sensing optical fiber.

7. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 1, characterized in that: The second protection unit includes a second protective cover sleeved on the first protection unit.

8. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 7, characterized in that: The second protection unit further includes a second reinforcement member, and the second reinforcement member is axially disposed through the second protective sleeve.

9. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 8, characterized in that: The second reinforcement member is a phosphated steel wire. There are two second reinforcement members, which are arranged in parallel and opposite to each other on both sides of the sensing optical fiber.

10. The distributed strain sensing optical cable suitable for direct burial installation in rock and soil according to claim 9, characterized in that: The second protection unit further includes a longitudinal steel strip, which is arranged between the first protection unit and the second protective cover. The outer wall and the inner wall of the longitudinal steel strip are both formed with embossing.

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