Temporary monitoring device of anchor chain laying posture and its monitoring and recovery method

Abstract

The present application relates to a kind of temporary monitoring device of anchor chain laying posture and its monitoring and recovery method, suitable for the monitoring field of ocean engineering and deep sea anchoring construction.The device is composed of four components: the recoverable towing head is detachably assembled at the end of anchor chain through controllable disengagement mechanism, integrated with USBL beacon for collecting position and three-dimensional tension sensor for detecting tension vector;Composite sensing optical cable with built-in distributed optical fiber is temporarily laid along anchor chain in parallel through multiple weak connection fixtures, and the tail end of optical cable is connected to the towing head;Ship-mounted launching and recovery system is provided on the construction ship, configured with recovery winch and connected to the head end of optical cable;Central control system is connected to each sensor and ship-mounted GPS.Working principle: the starting point of anchor chain curve is determined by USBL positioning, and the tangent direction of starting point is determined by the help of tension vector;Relying on optical fiber strain data, the curvature of each section of anchor chain is converted;By starting point along tangent direction, combined with curvature, piecewise integration is deduced, and three-dimensional coordinates of the whole anchor chain are sequentially solved, to complete the monitoring of anchor chain laying shape.

Description

Technical Field

[0001] This invention relates to a temporary monitoring device, method, and retrieval method for anchor chain laying posture. It is applicable to the field of construction monitoring technology for marine engineering and deep-sea mooring systems. Background Technology

[0002] During the deep-sea anchor chain laying process, the actual underwater morphology (caten shape) and bottom contact position of the anchor chain are key parameters for assessing whether the mooring system has achieved its design load-bearing capacity. However, traditional construction methods often rely on empirical formulas and calculations based on the construction vessel's position, making it difficult to accurately and in real-time grasp the actual underwater attitude of the anchor chain. If monitoring is carried out by permanently installing sensors such as fiber optic cables on the anchor chain, the sensors would be permanently buried on the seabed along with the anchor chain, resulting in high costs and non-recoverable equipment, significantly increasing the one-time investment in the project. This constitutes a significant technical bottleneck in the field of marine engineering, especially given the urgent economic requirements for the reuse of high-value equipment. Therefore, a temporary monitoring solution that can achieve both high-precision monitoring and the reuse of core equipment is urgently needed. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a temporary monitoring device for the anchor chain laying posture and a monitoring and recovery method thereof, in view of the above-mentioned problems.

[0004] The technical solution adopted in this invention is: a temporary monitoring device for the laying posture of anchor chains, comprising; The retrievable traction head is detachably connected to the end link of the anchor chain via a controllable release mechanism. It integrates a first USBL beacon for collecting the position information of the end of the anchor chain and a three-dimensional tension sensor for obtaining the direction of the tension vector at the end of the anchor chain. A composite sensing optical cable containing distributed optical fibers is laid in parallel with and temporarily fixed to an anchor chain through several weak connection fixing components. The end of the parallel weak connection sensing optical cable is connected to the recyclable traction head. The shipboard deployment and retrieval system includes a retrieval winch mounted on a construction vessel, which is connected to the head end of a composite sensing optical cable. The central control system is connected to the first USBL beacon, the three-dimensional tension sensor, the distributed optical fiber, and the shipborne GPS, and is configured to: determine the starting point of the curve based on the position information of the first USBL beacon; determine the tangential direction of the starting point based on the direction of the tension vector measured by the three-dimensional tension sensor; convert the fiber strain data of the distributed optical fiber into the bending curvature of each micro-segment of the anchor chain through the curvature formula; and gradually integrate along the tangential direction from the starting point to derive the three-dimensional spatial coordinates of the entire anchor chain.

[0005] Through the aforementioned technical means, on the one hand, by integrating multi-source data fusion from USBL beacons, three-dimensional tension sensors, and distributed optical fibers, the traditional empirical formulas and ship position calculation methods are replaced, enabling real-time and high-precision inversion of the three-dimensional morphology of the anchor chain. This allows for accurate determination of the anchor chain's true underwater attitude and bottom contact position, providing a reliable basis for assessing the bearing capacity of the mooring system. On the other hand, the use of a detachable and recyclable traction head and a composite sensing optical cable with weak connection fixation enables the recyclable design of the core monitoring equipment, avoiding the problem of sensors being permanently buried in the seabed and significantly reducing engineering monitoring costs.

[0006] As a preferred embodiment, the controllable release mechanism is a hydraulically driven quick release mechanism, including a hydraulic actuator, locking jaws, and a connecting platform; Under normal conditions, the locking claw is in a locked state, fixing the recyclable traction head to the end link of the anchor chain; upon receiving a wireless disengagement command from the water surface, the hydraulic actuator drives the locking claw to move upward and disengage from the end link of the anchor chain.

[0007] Through the above-mentioned technical means, remote and controllable separation of the retrievable towing head and anchor chain is achieved without the need for underwater manual or ROV assistance. The separation action is fast and highly reliable, and it can be adapted to anchor chain laying operations at any water depth, providing a structural foundation for the recovery of core equipment.

[0008] As a preferred embodiment, the weak connection fastener is a magnetic weak connection buckle, and the release tension threshold is set by adjusting the magnet spacing.

[0009] Through the above technical means, temporary parallel fixation of composite sensing optical cable and anchor chain is achieved. During the laying process, the optical cable can be kept close to the anchor chain without drifting. During the retrieval, it can be automatically disconnected under the preset tension, realizing the separation of optical cable and anchor chain without damage. Moreover, the magnetic buckle can be reused, further reducing costs.

[0010] As a preferred embodiment, the weak connection fastener is a biodegradable binding strap made of polylactic acid-based material, which gradually decreases in tensile strength after being soaked in water for a preset time.

[0011] Through the above technical means, temporary parallel fixation of composite sensing optical cable and anchor chain is achieved. During the laying process, the optical cable can be kept close to the anchor chain without drifting. During the retrieval, it can be automatically disconnected under the preset tension, realizing the separation of optical cable and anchor chain without damage.

[0012] As a preferred embodiment, the composite sensing optical cable includes armored sensing optical fibers and a high-strength polyurethane sheath wrapped around them.

[0013] As a preferred embodiment, the recyclable traction head adopts a streamlined pressure-resistant housing.

[0014] Through the above-mentioned technical means, the drag resistance of the towing head underwater is reduced, its hydrodynamic performance is improved, and it can adapt to deep-water operation environment. At the same time, the pressure-resistant shell can protect the internal integrated electronic components from the effects of seawater pressure and corrosion.

[0015] A method for monitoring and recovering the temporary monitoring device, comprising: S1. Connect the recyclable traction head to the end link of the anchor chain; lay the composite sensing optical cable in parallel with the anchor chain and temporarily fix it through several weak connection fasteners, and connect the end of the optical cable to the recyclable traction head, which is then connected to the recovery winch set on the construction vessel. S2. Start the anchor chain laying operation, and the traction head enters the water and touches the bottom with the anchor chain; the central control system simultaneously collects the real-time position information of the anchor chain end output by the first USBL beacon, the direction of the anchor chain end tension vector output by the three-dimensional tension sensor, the strain data of the entire anchor chain sensed by the distributed optical fiber, and the real-time positioning data of the construction vessel output by the shipborne GPS. S3. Based on the data collected in step S2, the central control system reconstructs the three-dimensional shape of the anchor chain in real time through a morphological inversion algorithm. S4. After the anchor chain is laid in place, the surface control console sends a wireless release command to activate the controllable release mechanism of the traction head, so that the traction head separates from the end link of the anchor chain. S5. Start the recovery winch to wind up the composite sensing optical cable. Under the action of recovery tension, all weak connection fasteners are disconnected from the anchor chain, and the entire composite sensing optical cable and the recyclable traction head connected to its end are simultaneously recovered to the deck of the construction vessel.

[0016] Through the above-mentioned technical means, the temporary monitoring of the anchor chain laying posture and the integrated recycling of the core equipment are realized. The monitoring process does not add extra time to the main operation of anchor chain laying, has minimal impact on the construction progress, and the recycling process is simple and efficient, enabling the core equipment to be reused throughout its entire life cycle.

[0017] As a preferred option, in step S4, the wireless detachment command sent by the surface control console is transmitted to the built-in control module of the retrievable towing head via the underwater acoustic communication device mounted on the construction vessel.

[0018] The beneficial effects of this invention are as follows: This invention uses USBL beacons to accurately locate the end position of the anchor chain, three-dimensional tension sensors to measure the bottom tension vector, distributed optical fibers to sense the strain distribution of the entire chain, and multi-source data fusion to invert the three-dimensional morphology of the anchor chain. Compared with traditional empirical formulas and ship position estimation methods, this invention significantly improves the monitoring accuracy and can accurately assess the construction quality and design bearing capacity of the mooring system.

[0019] This invention achieves separation of the traction head and anchor chain through a hydraulic quick-release mechanism and separation of the optical cable and anchor chain through a weak connection fastener. This allows the most valuable traction head and composite sensing optical cable to be completely recycled and reused, transforming the monitoring equipment from a "disposable consumable" to a "reusable tool," significantly reducing the one-time investment cost of deep-sea engineering monitoring.

[0020] The device of this invention has a reasonable structural design and a simple laying and recycling process, which does not affect the normal construction progress of anchor chain laying; at the same time, it avoids a large number of electronic devices and optical cables being permanently left on the seabed, reducing marine electronic waste and conforming to the development concept of green marine engineering. Attached Figure Description

[0021] Figure 1 A schematic diagram of the overall structure (laying state) of the temporary monitoring device for anchor chain laying posture provided by the present invention. Figure 2 for Figure 1 Enlarged partial view of the connection between the traction head and the end of the anchor chain (a, locked state; b, disengaged state; c, top view of the connection). Figure 3 A schematic diagram (plan view and cross-sectional view) of the laying method of the parallel weak connection sensing optical cable provided by the present invention. Figure 4 This is a flowchart of the monitoring and recovery method provided by the present invention.

[0022] in: 1-Construction vessel; 2-Anchor chain; 3-Chain guide; 4-Retrievable traction head; 4.1-First USBL beacon; 4.2-Three-dimensional tension sensor; 4.3-Streamlined pressure-resistant housing; 5-Hydraulic quick release mechanism; 5.1-Hydraulic actuator; 5.2-Locking jaws; 5.3-Connecting platform; 6- Composite sensing optical cable; 6.1- Armored sensing optical fiber; 6.2- High-strength polyurethane sheath; 6.3- Magnetic weak connection buckle; 7-Shipborne launch and recovery system; 7.1-Recovery winch; 7.2-Guide wheel; 8-Central control system; 8.1-Industrial control computer; 8.2-Optical demodulator; 8.3-Display. Detailed Implementation

[0023] Example 1: As Figure 1 As shown, this embodiment is a temporary monitoring device for the attitude of anchor chain laying, used for monitoring the attitude of construction vessel 1 when laying iron anchor chain 2. The anchor chain 2 enters the water from the stern chain guide 3 and extends towards the seabed.

[0024] In this example, the temporary monitoring device includes a retrievable towing head 4, a controllable release mechanism (in this example, a hydraulic quick release mechanism 5), a composite sensing optical cable 6, a shipborne launch and recovery system 7, and a central control system 8.

[0025] like Figure 1 , Figure 2 As shown, the retrievable towing head 4 adopts a streamlined pressure-resistant shell 4.3 design, with a length of about 2.0 meters, a maximum diameter of 0.8 meters, and a weight of about 2.5 tons. This design can effectively reduce the drag resistance of the towing head in deep water, ensuring its good hydrodynamic performance. At the same time, the pressure-resistant shell can withstand the high pressure environment of the deep sea and protect the internal electronic components.

[0026] In this example, a first USBL beacon 4.1 and a three-dimensional tension sensor 4.2 are integrated inside the towing head housing. The first USBL beacon 4.1 is used for precise underwater positioning and can output the three-dimensional spatial coordinates of the towing head in real time, providing absolute geometric boundaries for anchor chain morphology inversion. The three-dimensional tension sensor 4.2 has a range of 0-500 tons, an accuracy of ±0.5%FS, and a sampling frequency of 10Hz. It can measure the three-dimensional tension vector (Fx, Fy, Fz) at the bottom of the anchor chain in real time, providing mechanical boundary conditions for morphology inversion.

[0027] In this embodiment, the tail of the recyclable traction head 4 is detachably connected to the end link of the anchor chain 2 via a hydraulic quick release mechanism 5.

[0028] like Figure 2 As shown, the hydraulic quick-release mechanism 5 includes a built-in hydraulic actuator 5.1, locking claws 5.2, and a connecting platform 5.3. Under normal conditions, the locking claws 5.2 are in a locked state, firmly engaging the end link of the anchor chain 2, thus fixing the retrievable traction head 4 to the anchor chain 2. Upon receiving a wireless release command from the water surface, the hydraulic actuator 5.1 drives the locking claws 5.2 vertically upward, completely disengaging them from the anchor chain 2 link on the connecting platform 5.3, achieving a non-damaging separation of the traction head from the anchor chain.

[0029] like Figure 3 As shown, the composite sensing optical cable 6 is a composite optical cable containing an armored sensing optical fiber 6.1 and an outer high-strength polyurethane sheath 6.2. The cable diameter is 12mm and the tensile strength is 50kN, which can withstand the tensile force during deep-water laying and retrieval, thus preventing the cable from breaking.

[0030] The armored sensing fiber optic 6.1 uses distributed optical fiber based on BOTDA or BOTDR technology, which can sense the strain distribution of the entire anchor chain with a spatial resolution of 1 meter, providing full-chain deformation data for anchor chain morphology inversion.

[0031] In this embodiment, the composite sensing optical cable 6 is laid parallel to and temporarily fixed to the entire anchor chain 2 through several weak connection fasteners. In this embodiment, the weak connection fasteners are magnetic weak connection buckles 6.3. The release tension threshold is set to 200N by adjusting the magnet spacing. This threshold is much lower than the tensile strength of the optical cable, ensuring safe retrieval. Magnetic weak connection buckles are installed every 5 meters to ensure that the optical cable stays close to the anchor chain during laying and is not easily drifted.

[0032] In this example, the end of the composite sensing optical cable 6 is rigidly connected to the front of the housing of the retrievable traction head 4, and the head is connected to the shipborne deployment and retrieval system 7.

[0033] like Figure 1 As shown, the shipborne retrieval system 7 includes a retrieval winch 7.1 installed in the cabin of the construction vessel 1 and a guide wheel 7.2 on the deck. The first end of the composite sensing optical cable 6 passes through the guide wheel 7.2 and is wound onto the drum of the retrieval winch 7.1. The retrieval winch 7.1 can wind up the optical cable at a constant tension and uniform speed, so as to achieve smooth retrieval of the optical cable and the traction head.

[0034] like Figure 1 As shown, the central control system 8 is located in the control room of the construction vessel 1, and includes an industrial control computer 8.1, an optical demodulator 8.2 based on BOTDA or BOTDR technology, and a display 8.3.

[0035] The industrial control computer 8.1 is connected via cables to the three-dimensional tension sensor 4.2, the first USBL beacon 4.1, the optical demodulator 8.2, and the shipborne GPS to achieve synchronous acquisition of multi-source data. The optical demodulator 8.2 is used to analyze the optical signals of the distributed optical fiber and output the strain data of the entire anchor chain.

[0036] The industrial control computer 8.1 is equipped with a morphological inversion algorithm, which can reconstruct the three-dimensional morphology of the anchor chain in real time based on the collected multi-source data, and perform visualization rendering on the display 8.3 to intuitively display the underwater attitude of the anchor chain.

[0037] In this embodiment, the morphological inversion algorithm for the three-dimensional shape of the anchor chain is as follows: taking the measured position of the traction head as the starting point of the curve, and taking the direction of the tension vector measured by the three-dimensional tension sensor as the tangent direction of the starting point; converting the fiber strain data into the bending curvature of each micro-segment of the anchor chain through the curvature formula; starting from the starting point along the tangent direction, integrating step by step according to the curvature, and recursively deriving the three-dimensional spatial coordinates of the entire anchor chain.

[0038] Example 2: Using the temporary monitoring device described in Example 1, this example provides a temporary monitoring and retrieval method for anchor chain laying posture, including the following steps: S1. Temporary Laying Preparation Before the anchor chains are laid, the assembly of the equipment is completed on the deck of the construction vessel. The recyclable traction head 4 is connected to the end link of the anchor chain 2 via the hydraulic quick release mechanism 5, ensuring that the locking claw 5.2 is in the locked state; The composite sensing optical cable 6 is laid in parallel with the entire anchor chain 2 and temporarily fixed through the magnetic weak connection buckle 6.3, with a weak connection buckle installed every 5 meters; The end of the composite sensing optical cable 6 is rigidly connected to the front of the housing of the retrievable traction head 4, and the head end passes through the deck guide wheel 7.2 and is wound around the drum of the recovery winch 7.1; Complete the communication connection between the central control system 8 and each sensor and shipborne GPS, conduct system debugging, and ensure that all equipment is working properly.

[0039] S2, Anchor Chain Laying and Synchronous Monitoring The anchor chain laying operation is initiated. Anchor chain 2 enters the water from the stern chain guide 3, and the retrievable traction head 4 enters the water along with the front end of anchor chain 2 and eventually touches the bottom, being towed forward. During this process, the central control system 8 simultaneously collects the following four types of data: Real-time 3D positioning data of the tractor head output from the first USBL beacon 4.1; The three-dimensional tension data (Fx, Fy, Fz) at the bottom of the anchor chain output by the three-dimensional tension sensor 4.2 is sampled at a frequency of 10Hz. Distributed fiber strain data obtained by optical demodulator 8.2 with a spatial resolution of 1 meter; The construction vessel is equipped with GPS-enabled real-time positioning data.

[0040] S3, Real-time Inversion of Anchor Chain 3D Morphology The industrial control computer 8.1 of the central control system 8 uses an operational morphology inversion algorithm to reconstruct the three-dimensional morphology of the anchor chain in real time based on the collected multi-source data. The specific steps are as follows: The actual position of the traction head measured by the first USBL beacon 4.1 is taken as the starting point for calculating the catenary of the anchor chain; Using the direction of the tension vector measured by the three-dimensional tension sensor 4.2 as the starting point of the tangent direction, the initial direction of the anchor chain extending upward from the end is determined; The strain data acquired by distributed optical fibers is converted into the three-dimensional bending curvature of each 1-meter micro-segment of the anchor chain using the curvature-strain conversion formula of mechanics of materials, generating a curvature distribution sequence covering the entire anchor chain. Starting from the calculation point, along the initial tangent direction, and combining the curvature of each micro segment, the three-dimensional spatial coordinate point set of the entire anchor chain is derived step by step. The discrete three-dimensional coordinate points are connected into a continuous spatial curve, and the three-dimensional shape of the anchor chain is rendered in real time on the 8.3 display. The location of the construction vessel and seabed topography information are overlaid to allow construction personnel to monitor the anchor chain laying status in real time.

[0041] S4, Remote Hydraulic Disengagement Once anchor chain 2 has been laid to the designed length, and the central control system 8 has confirmed through real-time monitoring data that the anchor chain has landed stably and that key attitude data has been collected, the recovery process is initiated. The surface operator sends a wireless disengagement command from the control console of the central control system 8. The command is transmitted to the built-in control module of the retrievable towing head 4 via the underwater acoustic communication device on the construction vessel, triggering the hydraulic actuator 5.1 to move the locking claw 5.2 upward, so that the retrievable towing head 4 is completely separated from the end link of the anchor chain 2.

[0042] S5, Disconnection of Weak Connection and Equipment Recovery After successful detachment, the shipborne recovery winch 7.1 is activated to wind up the composite sensing optical cable 6 at a constant speed with a tension of approximately 500N. Since the recovery tension (500N) is greater than the detachment tension threshold (200N) of the magnetic weak connection buckle, all weak connection buckles will disconnect sequentially from the seabed to the water surface, completely separating the composite sensing optical cable 6 from the anchor chain 2.

[0043] As the optical cable continues to be wound up, the retrievable traction head 4 attached to its end is simultaneously pulled to the water surface and eventually retrieved to the deck of the construction vessel.

[0044] S6. Equipment Maintenance and Reuse The reusable towing head 4 recovered to the deck is subjected to the following treatments in sequence: fresh water rinsing to remove seawater salt and silt from the surface; drying to prevent internal electronic components from being damp and corroded; visual inspection of structural components to check for damage to the streamlined pressure-resistant housing and connection parts; and sensor accuracy calibration to calibrate the first USBL beacon 4.1 and the three-dimensional tension sensor 4.2 to ensure accurate data for the next use.

[0045] After passing the above-mentioned inspection, the recyclable traction head 4 and composite sensing optical cable 6 can be stored for later use and directly put into the next anchor chain laying and monitoring task, realizing the full life cycle reuse of the core equipment.

[0046] Example 3: Alternative to weak connection fasteners This embodiment is basically the same as Embodiment 1, except for the selection of the weak connection fastener.

[0047] Considering the high requirements for marine environmental protection in certain sea areas, this embodiment uses polylactic acid (PLA) based biodegradable binding tape as a weak connection fastener. The design parameters of this binding tape are: after being immersed in water for 24 hours, the tensile strength is greater than 300N, which can ensure that the optical cable will not fall off during the anchor chain laying process; after being immersed for 72 hours, the tensile strength gradually decreases to less than 50N.

[0048] During the recovery phase, when the recovery winch 7.1 is activated to wind up the optical cable with a pulling force of approximately 500N, the binding strap automatically breaks under the tension, separating the optical cable from the anchor chain. This method eliminates the need for a magnetic mechanism, making it more environmentally friendly, and the binding strap is biodegradable in seawater, preventing the generation of marine debris.

[0049] Example 4: Adaptation of the "lay chain first, then install anchor" construction process The temporary monitoring device and method of the present invention are also applicable to the construction process of "laying the chain first and then installing the anchor", and the specific implementation is as follows: Before installing the suction anchor, the anchor chain is pre-laid. The recyclable traction head 4 is temporarily connected to the end of the anchor chain 2 in place of the suction anchor. The attitude monitoring during the anchor chain pre-laying process is completed according to steps S1-S3 of Example 2. After confirming that the anchor chain is laid in place and the attitude meets the design requirements, the recyclable traction head 4 and the composite sensing optical cable 6 are retrieved according to steps S4-S6.

[0050] After the towing head and optical cable are retrieved, the suction anchor is installed to the end of anchor chain 2 with the assistance of an underwater robot (ROV), completing the final installation of the mooring system. This application method fully demonstrates the flexibility of this invention as a temporary monitoring tool, and it can adapt to different construction process requirements.

Claims

1. A temporary monitoring device for the laying posture of anchor chains, characterized in that, include; The retrievable traction head is detachably connected to the end link of the anchor chain via a controllable release mechanism. It integrates a first USBL beacon for collecting the position information of the end of the anchor chain and a three-dimensional tension sensor for obtaining the direction of the tension vector at the end of the anchor chain. A composite sensing optical cable containing distributed optical fibers is laid in parallel with and temporarily fixed to an anchor chain through several weak connection fixing components. The end of the parallel weak connection sensing optical cable is connected to the recyclable intelligent traction head. The shipboard deployment and retrieval system includes a retrieval winch mounted on a construction vessel, which is connected to the head end of a composite sensing optical cable. The central control system is connected to the first USBL beacon, the three-dimensional tension sensor, the distributed optical fiber and the shipborne GPS, and is configured to: determine the starting point of the curve based on the position information of the first USBL beacon, and determine the tangent direction of the starting point based on the direction of the tension vector measured by the three-dimensional tension sensor. The fiber strain data of the distributed optical fiber is converted into the bending curvature of each micro-segment of the anchor chain using the curvature formula. Starting from the starting point, integrate along the tangent direction according to the curvature to derive the three-dimensional spatial coordinates of the entire anchor chain.

2. The temporary monitoring device for anchor chain laying posture according to claim 1, characterized in that, The controllable release mechanism is a hydraulically driven quick release mechanism, including a hydraulic actuator, locking jaws and a connecting platform; Under normal conditions, the locking claw is in a locked state, fixing the recyclable traction head to the end link of the anchor chain; upon receiving a wireless disengagement command from the water surface, the hydraulic actuator drives the locking claw to move upward and disengage from the end link of the anchor chain.

3. The temporary monitoring device for anchor chain laying posture according to claim 1, characterized in that, The weak connection fastener is a magnetic weak connection buckle, and the release tension threshold is set by adjusting the magnet spacing.

4. The temporary monitoring device for anchor chain laying posture according to claim 1, characterized in that, The weak connection fastener is a biodegradable binding strap made of polylactic acid-based material, which gradually decreases in tensile strength after being soaked in water for a preset time.

5. The temporary monitoring device for anchor chain laying posture according to claim 1, characterized in that, The composite sensing optical cable includes armored sensing optical fibers and a high-strength polyurethane sheath wrapped around them.

6. The temporary monitoring device for anchor chain laying posture according to claim 1, characterized in that, The recyclable intelligent traction head adopts a streamlined pressure-resistant shell.

7. A method for monitoring and recovering the temporary monitoring device according to any one of claims 1 to 6, characterized in that, include: S1. Connect the recyclable traction head to the end link of the anchor chain; The composite sensing optical cable is laid and temporarily fixed in parallel with the anchor chain through several weak connection fasteners. The end of the optical cable is connected to a retrievable traction head and then to a recovery winch set on the construction vessel. S2. Start the anchor chain laying operation, and the traction head enters the water and touches the bottom with the anchor chain; the central control system simultaneously collects the real-time position information of the anchor chain end output by the first USBL beacon, the direction of the anchor chain end tension vector output by the three-dimensional tension sensor, the strain data of the entire anchor chain sensed by the distributed optical fiber, and the real-time positioning data of the construction vessel output by the shipborne GPS. S3. Based on the data collected in step S2, the central control system reconstructs the three-dimensional shape of the anchor chain in real time through a morphological inversion algorithm. S4. After the anchor chain is laid in place, the surface control console sends a wireless release command to activate the controllable release mechanism of the traction head, so that the traction head separates from the end link of the anchor chain. S5. Start the recovery winch to wind up the composite sensing optical cable. Under the action of recovery tension, all weak connection fasteners are disconnected from the anchor chain, and the entire composite sensing optical cable and the recyclable traction head connected to its end are simultaneously recovered to the deck of the construction vessel.

8. The monitoring and recovery method according to claim 7, characterized in that, In step S4, the wireless detachment command sent by the surface control console is transmitted to the built-in control module of the retrievable towing head via the underwater acoustic communication device mounted on the construction vessel.

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