A sensing optical cable protection structure and arrangement for marine flexible pipe and a method of monitoring

Abstract

The application belongs to the technical field of marine pipeline laying and monitoring, and proposes a sensing optical cable protection structure for marine flexible pipe cable and a laying and monitoring method. The diameter of the non-interference loose sleeve circular accommodating cavity of the protection structure is greater than the diameter of the optical cable, so that the optical cable and the pipe cable main structure have independent deformation buffer space. When the pipe cable is subjected to tensile-bending-torsional deformation and water pressure radial compression, the protection sleeve absorbs the deformation, and the optical cable does not directly bear the tensile, bending, torsion and water pressure extrusion load of the pipe cable. The segmented forming and staggered buckling installation arrangement make the protection structure embedded in the pipe cable in the form of replacing the armored unit, so that the optical cable is completely separated from the interlayer contact of the pipe cable, and the damage of the optical cable caused by interlayer friction and extrusion is avoided. On this basis, the optical cable accommodated in the protection cavity can stably collect strain data for a long time, and the continuous and effective monitoring of the three-dimensional spatial line type, deformation distribution, bending and torsional state and cross-section stress state of the pipe cable is realized.

Description

Technical Field

[0001] This invention relates to the field of marine pipeline laying and monitoring technology, and in particular to a sensor optical cable protection structure and its arrangement and monitoring method for marine flexible pipelines. Background Technology

[0002] In the deep-sea field, marine flexible pipelines often drift over a wide area due to ocean currents and waves, or move extensively due to mining needs. The combined effects of tension-bending-torsion loads and the high water pressure in the deep sea cause repeated changes in the pipeline's shape and cross-sectional deformation, which can easily lead to fatigue damage and structural failure. Therefore, real-time monitoring of changes in the pipeline's shape is crucial for timely early warning and repair of other failure modes such as pipeline temperature and leakage.

[0003] Existing flexible conduits mostly use fiber optic monitoring, but the fiber optic cable is usually directly embedded into the armor layer of the conduit or attached to the interlayer of the conduit. This installation method results in close contact between the fiber optic cable and the main structure of the conduit, and the stress and deformation of the conduit are directly transmitted to the fiber optic cable, leading to structural damage. Especially in the high-pressure environment of the deep sea, fiber optic cables attached to the interlayer of the conduit are also prone to damage due to interlayer friction, compression, and radial compression from water pressure. All of these factors can cause premature damage to the fiber optic cable during the operation of the conduit, making it impossible to perform monitoring tasks effectively for a long period of time. Summary of the Invention

[0004] Therefore, one objective of this invention is to propose a sensor optical cable protection structure and arrangement and monitoring method for marine flexible tubular cables, so as to solve the problems mentioned in the background art and overcome the shortcomings of the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a protective structure for a sensing optical cable for a flexible marine cable, comprising an inner protective sleeve and an outer protective sleeve; The inner protective sleeve has an arc-shaped groove, and the outer protective sleeve has an arc-shaped groove cover that matches the arc-shaped groove. After the inner protective sleeve and the outer protective sleeve are snapped together, the arc-shaped groove and the arc-shaped groove cover form a receiving cavity with a circular cross-section, which is used to accommodate the monitoring optical cable. The diameter of the receiving cavity is larger than the diameter of the monitoring optical cable, so that there is a movable gap between the monitoring optical cable and the inner wall of the receiving cavity.

[0006] Preferably, the central angle of the arc-shaped groove is greater than 180°, the sum of the central angle of the arc-shaped groove cover and the central angle of the arc-shaped groove is equal to 360°, and the radii of the arc-shaped groove and the arc-shaped groove cover are equal, so that the inner wall of the receiving cavity formed by the arc-shaped groove and the arc-shaped groove cover has no sharp corners.

[0007] Preferably, the outer side wall of the inner protective sleeve is provided with an outer groove, and the inner side wall of the outer protective sleeve is provided with an inner protrusion that matches the outer groove. The inner protrusion is embedded in the outer groove to form a positioning slot.

[0008] Preferably, after the inner protective sleeve and the outer protective sleeve are snapped together, the overall cross-section is rectangular.

[0009] Preferably, both the inner protective sleeve and the outer protective sleeve are made of carbon fiber or glass fiber reinforced composite material.

[0010] Secondly, the present invention provides a method for arranging a protective structure for a sensing optical cable used in a marine flexible cable, based on the aforementioned protective structure for a sensing optical cable used in a marine flexible cable, comprising: Insert the monitoring optical cable into the arc-shaped groove of the inner protective sleeve, with the opening side of the inner protective sleeve facing outwards; Cover the inner protective sleeve with the outer protective sleeve, and use crimping pliers to crimp the two together to form a protective sleeve unit; The protective sleeve unit replaces one or more armor units in the rectangular cross-section armor layer of the marine flexible cable, so that the protective sleeve unit is spirally wound and formed along with the armor layer.

[0011] Preferably, the inner protective sleeve and the outer protective sleeve are joined together in a segmented molding and staggered fastening manner to form a protective sleeve unit, including: Divide the length of each segment into units of one spiral cycle, and mass-produce inner and outer protective sleeves; The inner and outer protective sleeves are crimped together in an axial manner to form a protective sleeve unit, and the length of the overlapping section of the crimped inner and outer protective sleeves is greater than one-quarter of the length of a single spiral cycle.

[0012] Preferably, the jaws of the clamping pliers are provided with a buffer pad, which is made of rubber material.

[0013] Preferably, the overall thickness of the protective sleeve unit is equal to the thickness of the armor layer in the rectangular cross-section.

[0014] Thirdly, the present invention provides a method for monitoring marine flexible cable, based on the above-mentioned protection structure and arrangement method, comprising: Obtain the cable's coordinates at the initial arc length. Initial configuration axis position and the current configuration axis position ; Based on the initial configuration axis position and the current configuration axis position Calculate the displacement field of the cable ; Based on the current configuration axis position Calculate the deformation gradient tensor ; Based on the deformation gradient tensor Calculate the Green-Lagrange strain tensor And based on the strain tensor Determine the axial strain of the cable ; Based on satellite orthogonal base The derivative operation is used to determine the curvature vector of the cable. The curvature vector Includes two transverse curvature components , and a torsion component ; Based on the axial strain Curvature vector In addition to the cable section stiffness parameters, the axial force on the cable section is calculated. Torque and bending moment , ; Based on the current configuration axis position The three-dimensional spatial linear change of the output cable is based on the axial strain. Assess cable deformation distribution based on the curvature vector. Assess the bending and torsional state of the cable based on the axial force. Torque and bending moment , Assess the stress state of the cable section; when the axial strain curvature axial force Torque and bending moment , When any one of the following exceeds a preset safety threshold, an early warning signal is generated.

[0015] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: This invention solves the problems of fatigue damage and structural failure caused by repeated changes in cable shape and cross-sectional deformation under tension-bending-torsion coupling loads and high water pressure in the deep sea. It also addresses the problems caused by the direct embedding of optical cables into the armor layer or between layers, resulting in the direct transfer of stress deformation from the cable to the optical cable. This is achieved by using an inner protective sleeve and an outer protective sleeve to form a non-interference loose circular cavity, which houses the monitoring optical cable. Furthermore, it addresses the problems caused by the radial compression of the cable cross-section under high water pressure in the deep sea, which further aggravates interlayer friction and extrusion, leading to premature damage of the optical cable and the inability to conduct long-term effective monitoring.

[0016] Specifically, the diameter of the non-interference loose-tube circular cavity is larger than the diameter of the optical cable, so that there is an independent deformation buffer space between the optical cable and the main structure of the cable tube. When the cable tube is subjected to tensile-bending-torsional deformation and radial compression by water pressure, the protective sleeve absorbs the deformation. The optical cable does not directly bear the tensile, bending, torsion and water pressure extrusion loads of the cable tube, thereby avoiding damage to the optical cable structure and micro-bending loss of the optical fiber. The inner and outer protective sleeves are made of carbon fiber or glass fiber reinforced composite materials, which have high compressive strength and can withstand radial compression in the high water pressure environment of the deep sea without crushing. The segmented molding and staggered crimping installation arrangement allows the protective structure to be embedded into the cable in a way that replaces the armor unit, ensuring the overall mechanical continuity of the cable and completely separating the optical cable from the interlayer contact of the cable, thus avoiding damage to the optical cable caused by interlayer friction and compression. Based on this, the optical cable installed in the cavity can collect strain data stably for a long time, realizing continuous and effective monitoring of the cable's three-dimensional spatial shape, deformation distribution, bending and torsion state and cross-sectional stress state, providing a reliable early warning and repair basis for cable failure modes such as abnormal temperature and leakage.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram showing the relative position of the protective sleeve structure and the optical cable in an embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-section of the inner protective sleeve in an embodiment of the present invention; Figure 3 This is a schematic diagram of the cross-section of the outer protective sleeve according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the cross-section of a flexible pipe according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the segmented staggered crimping installation according to an embodiment of the present invention; Figure 6 This is a partial schematic diagram of the segmented staggered clamping installation according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the inner and outer sheath fitting method at the connection point in an embodiment of the present invention; Figure 8 This is a schematic diagram of the crimping installation tool according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the end cover according to an embodiment of the present invention; Figure 10 This is a schematic diagram illustrating the steps of the arrangement method for the protective structure of the sensing optical cable for marine flexible tubular cable according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the steps of the marine flexible cable monitoring method according to an embodiment of the present invention; Figure 12 This is a flowchart illustrating the principle of cable monitoring in an embodiment of the present invention.

[0019] The components include: 1. Inner protective sleeve; 2. Outer protective sleeve; 3. Monitoring optical cable; 4. Arc-shaped groove; 5. Arc-shaped groove cover; 6. End face cover; 7. Flexible conduit cable; 8. Circular cross-section armor layer; 9. Rectangular cross-section armor layer; 10. Staggered crimping overlap section; 11. Outer groove; 12. Inner protrusion; 13. Clamp body; 14. Pin; 15. Buffer pad. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] This invention provides a protective structure for a sensing optical cable used in a marine flexible tubular cable, comprising an inner protective sleeve 1 and an outer protective sleeve 2; The inner protective sleeve 1 is provided with an arc-shaped groove 4, and the outer protective sleeve 2 is provided with an arc-shaped groove cover 5 that matches the arc-shaped groove 4; After the inner protective sleeve 1 and the outer protective sleeve 2 are snapped together, the arc-shaped groove 4 and the arc-shaped groove cover 5 form a receiving cavity with a circular cross-section, which is used to accommodate the monitoring optical cable 3. The diameter of the receiving cavity is larger than the diameter of the monitoring optical cable 3, so that there is a movable gap between the monitoring optical cable 3 and the inner wall of the receiving cavity.

[0022] Furthermore, the central angle of the arc-shaped groove 4 is greater than 180°, the sum of the central angle of the arc-shaped groove cover 5 and the central angle of the arc-shaped groove 4 is equal to 360°, and the radii of the arc-shaped groove 4 and the arc-shaped groove cover 5 are equal, so that the inner wall of the receiving cavity formed by the arc-shaped groove 4 and the arc-shaped groove cover 5 has no sharp corners.

[0023] Furthermore, the outer side wall of the inner protective sleeve 1 is provided with an outer groove 11, and the inner side wall of the outer protective sleeve 2 is provided with an inner protrusion 12 that is adapted to the outer groove 11. The inner protrusion 12 is embedded in the outer groove 11 to form a positioning slot.

[0024] Furthermore, after the inner protective sleeve 1 and the outer protective sleeve 2 are snapped together, the overall cross-section is rectangular.

[0025] By making the inner protective sleeve 1 and the outer protective sleeve 2 together with a rectangular cross-section, the protective structure is adapted to the shape and size of the rectangular cross-section armor unit commonly used in the armor layer of the flexible cable 7. This allows it to be seamlessly embedded into the cable body in a way that replaces the armor unit, ensuring the continuity of the overall cross-sectional profile and the consistency of mechanical transmission. On the other hand, the rectangular cross-section has higher structural stability and resistance to external pressure than the circular cross-section. It is less prone to buckling deformation or cross-sectional crushing in the high water pressure environment of the deep sea, and can better maintain the geometry of the protective structure itself. This ensures that the space of the internal non-interference loose sleeve cavity is not compressed, and avoids the monitoring optical cable 3 contained therein from being damaged by radial compression.

[0026] Furthermore, both the inner protective sleeve 1 and the outer protective sleeve 2 are made of carbon fiber or glass fiber reinforced composite materials.

[0027] Specifically, such as Figures 1-9 As shown, the main components of the protective structure include an inner protective sleeve 1, an outer protective sleeve 2, and the protected monitoring optical cable 3. The inner protective sleeve 1 and the outer protective sleeve 2 are a snap-fit ​​structure, with the protected optical cable primarily housed in the arc-shaped groove 4 of the inner protective sleeve 1. When the inner protective sleeve 1 and the outer protective sleeve 2 are snapped together, the inner protective sleeve 1 is embedded into the outer protective sleeve 2. The arc-shaped groove 4 of the inner protective sleeve 1 and the arc-shaped groove cover 5 of the outer protective sleeve 2 connect to form a complete circular receiving cavity, meaning the radius r of the arc-shaped groove 4 and the arc-shaped groove cover 5 are equal, and the central angles of the two arcs are... and The sum equals 360°, ensuring the inner cavity is a circular cavity without any obvious sharp corners, preventing excessive wear on the optical cable due to movement inside. After crimping, an end cap 6 should be nested at the end. For the arc-shaped groove 4 of the inner protective sleeve 1, its opening width w must be greater than or equal to the diameter of the protected monitoring optical cable 3, and the central angle... The angle should be greater than 180° to allow the optical cable to be directly inserted and ensure that most of the cable is contained within the groove. For the groove radius R of the inner protective sleeve 1 and the outer protective sleeve 2, its curvature 1 / R should be slightly greater than 0, but not too large, to prevent structural damage during clamping and to ensure a stable overall structure after clamping. Considering that the inner protective sleeve 1 and the outer protective sleeve 2 have irregular cross-sectional structures, carbon fiber or glass fiber reinforced composite materials can be used. Resin transfer molding or prepreg molding methods can be employed, where fiber preforms are layered in a mold to form a specific cross-section, which is then hot-pressed.

[0028] In one embodiment, such as Figure 10 As shown, the present invention also provides a method for arranging a protective structure for a sensing optical cable in a marine flexible duct cable, which, based on the above-mentioned protective structure for a sensing optical cable in a marine flexible duct cable, includes: S1: Place the monitoring optical cable 3 into the arc-shaped groove 4 of the inner protective sleeve 1, and make the open side of the inner protective sleeve 1 face outward. S2: Cover the inner protective sleeve 1 with the outer protective sleeve 2, and use crimping pliers to crimp the two together to form a protective sleeve unit; S3: Replace one or more armor units in the rectangular cross-section armor layer 9 of the marine flexible cable 7 with the protective sleeve unit, so that the protective sleeve unit is spirally wound and formed with the armor layer.

[0029] Furthermore, the inner protective sleeve 1 and the outer protective sleeve 2 are joined together in a segmented molding and staggered fastening manner to form a protective sleeve unit, including: Divide the length of each segment into units of one spiral cycle, and mass-produce inner protective sleeve 1 and outer protective sleeve 2; The inner protective sleeve 1 and the outer protective sleeve 2 are crimped together in an axial manner to form a protective sleeve unit, and the length of the overlapping section 10 of the inner protective sleeve 1 and the outer protective sleeve 2 is greater than one-quarter of the length of a single spiral cycle.

[0030] Furthermore, the jaws of the clamping pliers are provided with a buffer pad 15, which is made of rubber material.

[0031] Furthermore, the overall thickness of the protective sleeve unit is equal to the thickness of the armor layer 9 in the rectangular cross section.

[0032] Specifically, regarding the layout and installation method, the common flexible conduit cable 7 typically includes an armor layer formed by spiral winding, including a circular cross-section armor layer 8 and a rectangular cross-section armor layer 9. One or more armor units in the armor layer can be replaced with pre-clipped optical cable units. The overall structural thickness should be equal to the armor layer thickness. During the layout, considering that the inner protective sleeve 1 and outer protective sleeve 2 are irregularly shaped and crimped, direct continuous molding might affect the crimping installation. Therefore, a method such as... Figure 5The installation is performed using the segmented molding and staggered crimping method shown. Figure 5 The arrows indicate the direction of the spiral winding, and the point where the arrows meet indicates the point where the previous segment meets the next segment. Figure 5 The three sets of lines in the diagram represent the monitoring optical cable 3 in the middle, and the lines on either side represent the inner protective sleeve 1 and the outer protective sleeve 2, respectively. The inner and outer protective sleeves 1 and 2 protect the monitoring optical cable 3. The inner and outer protective sleeves 1 and 2 can be segmented in one spiral cycle (360°), with the length of the overlapping interlocking section 10 preferably greater than a quarter of a spiral cycle. Alternatively, half a cycle (180°) can be used as the segment unit. Shorter cycles (10°–20°) can also be used as segment units, making each segment nearly straight and easier to manufacture and install. At the interlocking position, the inner and outer protective sleeves 1 and 2 have corresponding outer grooves 11 and inner protrusions 12, forming a slot structure. This ensures the integrity of the structure after installation and avoids excessive cumulative installation errors caused by non-positioning installation.

[0033] Understandably, the spiral winding structure is a spiral wound with an equal inclination angle, wrapped around the inner cylinder of the cable. One spiral cycle is the spiral winding around the cylinder once.

[0034] During installation, the inner protective sleeve 1 should first be placed over the optical cable with the opening side of the inner protective sleeve 1 facing outwards. Then, the outer protective sleeve 2 should be placed over the inner protective sleeve 1. The two should be joined together using crimping pliers. The crimping pliers include two clamp bodies 13 connected by pins 14. The clamp jaws should include a buffer pad 15 made of low-hardness materials such as rubber to prevent damage to the protective sleeve during crimping.

[0035] It is understandable that the present invention combines segmented molding and staggered crimping to solve the difficulty of continuous molding of long-length irregular cross-section sheaths, while avoiding the problem that long-length sheaths are not easy to nest and install.

[0036] In addition, the entire structure is completely inside the submarine cable structure, so it will not be corroded by seawater, and there is no need to attach or hang other equipment, ensuring good integrity.

[0037] In one embodiment, such as Figure 11 and Figure 12 As shown, the present invention also provides a method for monitoring marine flexible cables, based on the above-described protection structure and arrangement method, comprising: A1: Obtain the cable's initial arc length coordinates Initial configuration axis position and the current configuration axis position ; A2: Based on the initial configuration axis position and the current configuration axis position Calculate the displacement field of the cable ; A3: Based on the current configuration axis position Calculate the deformation gradient tensor ; A4: Based on the aforementioned deformation gradient tensor Calculate the Green-Lagrange strain tensor And based on the strain tensor Determine the axial strain of the cable ; A5: Based on satellite orthogonal basis The derivative operation is used to determine the curvature vector of the cable. The curvature vector Includes two transverse curvature components , and a torsion component ; A6: Based on the aforementioned axial strain Curvature vector In addition to the cable section stiffness parameters, the axial force on the cable section is calculated. Torque and bending moment , ; A7: Based on the current configuration axis position The three-dimensional spatial linear change of the output cable is based on the axial strain. Assess cable deformation distribution based on the curvature vector. Assess the bending and torsional state of the cable based on the axial force. Torque and bending moment , Assess the stress state of the cable section; when the axial strain curvature axial force Torque and bending moment , When any one of the following exceeds a preset safety threshold, an early warning signal is generated.

[0038] Specifically, within the framework of continuum mechanics, a helix is ​​considered as an elongated body with a tiny cross-section. The axis of the initial configuration P... The axis of the current configuration Q is a straight line. Let be any space curve, where These are the initial arc length coordinates. If the helix is ​​derived from the parametric equations... The axis can be described by the angle of the cross section. The integral yields: ; Let the positions of each mass point on the central axis of the cable corresponding to the initial configuration P be... The orthogonal basis of the satellite is The corresponding point position in the current configuration Q is The orthogonal basis of the satellite is . It can be obtained from the displacement field and Represented as: ; Deformation gradient tensor: ; The Green-Lagrange strain tensor can be expressed as: ; The axial strain of the cable can then be expressed as: ; To solve for the bending and torsional deformation of the cable, it is necessary to determine the change in the cable curvature vector. Since the initial configuration is preset to be a straight line, the initial curvature is 0, and the change in the curvature vector is... The curvature vector is equal to that under the current configuration, and is It can be represented as ; in It can be represented as: ; so The final representation is: ; Based on the deformation parameters obtained above, the axial force, torque, and bending moment at various points on the cable can be calculated.

[0039] The axial force is: ; The torque is: ; The two bending moments perpendicular to the axis are as follows: ; ; In the above formula, For elastic modulus, Shear modulus For the moment of inertia of the cross section in different directions, It is the polar moment of inertia; For tensile stiffness, To increase torsional stiffness, For bending stiffness, For the equivalent cross-sectional area of ​​the cable, The twist rate of the cable. of , of It is a three-dimensional orthogonal basis. The direction index, with values ​​1, 2, and 3, corresponds to... The three basis vector directions, The Levi-Civita symbol, in which For free indices, corresponding to curvature vectors The One portion, and To obtain the dummy index, values ​​1, 2, and 3 are used, corresponding to... Three basic vector directions, and cross-sectional moments of inertia in different directions. and The directions are corresponding, here It takes the values ​​1 and 2.

[0040] The above formula can be used to monitor cable profile, cable deformation, vector, and cable stress.

[0041] As one implementation, in step A1 above, the initial configuration axis position The position of the current configuration axis can be determined from the initial cable laying measurement data; It can be obtained in the following ways: Strain data is acquired via a monitoring optical cable 3 housed within a protective structure. The monitoring optical cable 3 may include at least one centrally located sensing fiber and at least two eccentrically located sensing fibers. Axial displacement components are obtained by integrating the axial strain data acquired from the central fiber, and curvature vectors are obtained by inverting the differential strain data acquired from the eccentric fibers. , and then combine The position of the current configuration axis is obtained through numerical integration. .

[0042] Based on this, the displacement field in step A2 above This can be obtained from the calculation. and The deformation gradient tensor obtained in step A3 is obtained through differential calculus. can be right The derivative is obtained in step A4 based on this deformation gradient tensor. The Green-Lagrange strain tensor can be further calculated. And thus determine the axial strain of the cable. The curvature vector in step A5 The curvature vector obtained from the differential strain inversion of the eccentric fiber can be used directly. Those skilled in the art can also, as needed, combine satellite orthogonal bases The derivative operation is used to verify or assist in determining the curvature vector; subsequently, based on the axial strain... and curvature vector By combining the preset cable section stiffness parameters, the axial force on the cable section can be calculated. Torque and bending moment , Finally, based on the current configuration axis position... Axial strain Curvature vector In addition to the aforementioned internal force parameters, the system outputs the three-dimensional spatial changes in the cable profile and performs monitoring, evaluation, and early warning.

[0043] It should be noted that the above-described method of acquiring strain data via optical fiber to invert the alignment is merely a preferred engineering implementation of the monitoring method of this invention. At the theoretical level, the protection of this invention is not limited to specific sensing methods; any means capable of obtaining the current configuration axis position of the cable is permitted. All methods described herein fall within the scope of protection of this invention.

[0044] Compared with the prior art, the present invention has the following advantages: This invention solves the problems of fatigue damage and structural failure caused by repeated changes in the linearity and cross-sectional deformation of cables under tension-bending-torsion coupled loads and high water pressure in the deep sea, as well as the problems caused by the direct embedding of optical cables into the armor layer or the direct transfer of stress deformation from the cable to the optical cable by the direct embedding of the inner protective sleeve 1 and the outer protective sleeve 2 together to form a non-interference loose circular cavity, and the inclusion of the monitoring optical cable 3 in the cavity by a segmented forming and staggered crimping process.

[0045] Specifically, the diameter of the non-interference loose-tube circular cavity is larger than the diameter of the optical cable, so that there is an independent deformation buffer space between the optical cable and the main structure of the cable tube. When the cable tube is subjected to tensile-bending-torsional deformation and radial compression by water pressure, the protective sleeve absorbs the deformation. The optical cable does not directly bear the tensile, bending, torsion and water pressure extrusion loads of the cable tube, thereby avoiding damage to the optical cable structure and micro-bending loss of the optical fiber. The inner and outer protective sleeves are made of carbon fiber or glass fiber reinforced composite materials, which have high compressive strength and can withstand radial compression in the high water pressure environment of the deep sea without crushing. The segmented molding and staggered crimping installation arrangement allows the protective structure to be embedded into the cable in a way that replaces the armor unit, ensuring the overall mechanical continuity of the cable and completely separating the optical cable from the interlayer contact of the cable, thus avoiding damage to the optical cable caused by interlayer friction and compression. Based on this, the optical cable installed in the cavity can collect strain data stably for a long time, realizing continuous and effective monitoring of the cable's three-dimensional spatial shape, deformation distribution, bending and torsion state and cross-sectional stress state, providing a reliable early warning and repair basis for cable failure modes such as abnormal temperature and leakage.

[0046] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] It will be readily understood by those skilled in the art that this invention includes any combination of the inventive description and specific embodiments outlined in the foregoing specification, as well as the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0048] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A protective structure for sensing optical cables used in marine flexible conduits, characterized in that, Includes an inner protective sleeve and an outer protective sleeve; The inner protective sleeve has an arc-shaped groove, and the outer protective sleeve has an arc-shaped groove cover that matches the arc-shaped groove. After the inner protective sleeve and the outer protective sleeve are snapped together, the arc-shaped groove and the arc-shaped groove cover form a receiving cavity with a circular cross-section, which is used to accommodate the monitoring optical cable. The diameter of the receiving cavity is larger than the diameter of the monitoring optical cable, so that there is a movable gap between the monitoring optical cable and the inner wall of the receiving cavity.

2. The sensor optical cable protection structure for marine flexible conduit cables as described in claim 1, characterized in that, The central angle of the arc-shaped groove is greater than 180°, the sum of the central angle of the arc-shaped groove cover and the central angle of the arc-shaped groove is equal to 360°, and the radii of the arc-shaped groove and the arc-shaped groove cover are equal, so that the inner wall of the receiving cavity formed by the arc-shaped groove and the arc-shaped groove cover has no sharp corners.

3. The sensor optical cable protection structure for marine flexible tubular cables as described in claim 1, characterized in that, The outer side wall of the inner protective sleeve is provided with an outer groove, and the inner side wall of the outer protective sleeve is provided with an inner protrusion that matches the outer groove. The inner protrusion is embedded in the outer groove to form a positioning slot.

4. The sensor optical cable protection structure for marine flexible tubular cables as described in claim 1, characterized in that, After the inner protective sleeve and the outer protective sleeve are snapped together, the overall cross-section is rectangular.

5. The sensor optical cable protection structure for marine flexible tubular cables as described in claim 1, characterized in that, Both the inner protective sleeve and the outer protective sleeve are made of carbon fiber or glass fiber reinforced composite materials.

6. A method for arranging a protective structure for a sensing optical cable in a marine flexible tubular cable, based on the protective structure for a sensing optical cable in a marine flexible tubular cable as described in any one of claims 1-5, characterized in that, include: Insert the monitoring optical cable into the arc-shaped groove of the inner protective sleeve, with the opening side of the inner protective sleeve facing outwards; Cover the inner protective sleeve with the outer protective sleeve, and use crimping pliers to crimp the two together to form a protective sleeve unit; The protective sleeve unit replaces one or more armor units in the rectangular cross-section armor layer of the marine flexible cable, so that the protective sleeve unit is spirally wound and formed along with the armor layer.

7. The arrangement method for the protection structure of the sensing optical cable for marine flexible tubular cables as described in claim 6, characterized in that, The inner protective sleeve and the outer protective sleeve are joined together in a segmented molding and staggered snap-fit ​​manner to form a protective sleeve unit, including: Divide the length of each segment into units of one spiral cycle, and mass-produce inner and outer protective sleeves; The inner and outer protective sleeves are crimped together in an axial manner to form a protective sleeve unit, and the length of the overlapping section of the crimped inner and outer protective sleeves is greater than one-quarter of the length of a single spiral cycle.

8. The arrangement method for the protection structure of the sensing optical cable for marine flexible tubular cables as described in claim 6, characterized in that, The jaws of the clamping pliers are equipped with a buffer pad, which is made of rubber material.

9. The arrangement method for the protection structure of the sensing optical cable for marine flexible tubular cables as described in claim 6, characterized in that, The overall thickness of the protective sleeve unit is equal to the thickness of the armor layer in the rectangular cross section.

10. A method for monitoring marine flexible tubular cables, based on the protection structure described in any one of claims 1-5 and the arrangement method described in any one of claims 6-9, characterized in that, include: Obtain the initial configuration axis position and the current configuration axis position of the cable in the initial arc length coordinate system; Based on the initial configuration axis position and the current configuration axis position, calculate the displacement field of the cable; Calculate the deformation gradient tensor based on the current configuration axis position; Based on the deformation gradient tensor, the Green-Lagrange strain tensor is calculated, and the axial strain of the cable is determined based on the strain tensor. Based on the derivative operation of the body orthogonal basis, the curvature vector of the cable is determined, which includes two transverse curvature components and one torsional component. Based on the axial strain, curvature vector, and cable section stiffness parameters, the axial force, torque, and bending moment acting on the cable section are calculated. Based on the current configuration axis position, the cable's three-dimensional spatial linear change is output; based on the axial strain, the cable's deformation distribution is evaluated; based on the curvature vector, the cable's bending and torsional state is evaluated; based on the axial force, torque, and bending moment, the cable's cross-sectional stress state is evaluated; when any one of the axial strain, curvature, axial force, torque, and bending moment exceeds a preset safety threshold, an early warning signal is generated.

Images