Concrete ecological fish reef offshore smooth hoisting construction method

Abstract

The present application relates to the technical field of ocean engineering construction, and discloses a kind of concrete ecological fish reef offshore smooth hoisting construction method, including the underwater base bed is explored using measurement system, and the long arm excavator is controlled to carry out leveling and retest to the top surface of underwater base bed;Using anchor boat to assist water crane ship to stay, concrete ecological fish reef is transported to the side of water crane ship;Special lifting device is lowered to connect concrete ecological fish reef test lifting to check stress state;Fish reef is lifted and anchor chain is adjusted to coordinate ship position, and is lowered to underwater base bed again after moving to the above of target area;After touching bottom, keep lifting and hanging to check and place posture, qualified to release connection to complete group placement and retest.By quantifying the bearing parameters of water staying and lifting rigging, combined with the excavation and leveling control of base bed and the sectional hoisting process of hovering landing position, the reef body inclination and collision caused by underwater rapid drop casting are excluded, and the design requirements of fish reef group arrangement are met.

Description

Technical Field

[0001] This invention relates to the field of marine engineering construction technology, specifically a method for the stable offshore hoisting and construction of concrete ecological artificial reefs. Background Technology

[0002] Artificial reefs are essential infrastructure for improving the marine ecological environment. The deployment of large reinforced concrete artificial reefs typically relies on offshore cranes to lift them from the sea surface to the target seabed. In actual marine construction environments, the underwater substrate morphology is complex. Traditional substrate leveling operations often employ extensive mechanical leveling or heavy-load dumping, lacking a height feedback mechanism that integrates real-time water level and excavator status. This results in numerous misalignments and steep slopes remaining on the leveled substrate surface. Placing large-volume concrete reefs directly on an unleveled surface leads to localized stress concentration and overall tilting.

[0003] During the vessel positioning and lifting operations, wind, waves, and ocean currents continuously and dynamically disturb the construction vessel. Traditional construction methods have vague definitions of the load-bearing capacity of the vessel's anchoring system and lifting rigging, failing to quantitatively verify parameters based on the vessel's draft, seabed composition, and component weight. Under the superposition of wave loads, there are safety hazards such as vessel dragging anchor and rigging overload. Existing lifting and lowering processes mostly adopt a crude mode of direct descent to the bottom in one go, lacking stress testing at the initial lifting stage and hovering re-measurement of elevation nodes after entry into the water. The kinetic energy of the water surface swaying is directly transmitted along the rigging, making it difficult to control the lowering attitude of the artificial reef, causing it to deviate from the design coordinates at the moment of bottoming or collide and break with the installed reef. The conventional operation of immediately detaching the lifting equipment after the artificial reef touches the bottom ignores the initial settlement process of the underwater rock-filled foundation under pressure, resulting in secondary displacement of the artificial reef after detachment, failing to achieve the design requirements of multiple reefs closely abutting and arranged in groups in an ecological artificial reef cluster. Summary of the Invention

[0004] The technical problem solved by this invention is that, in the existing technology for hoisting concrete ecological artificial reefs in a marine environment, the operating vessel is difficult to maintain a stable position due to the disturbance of waves and ocean currents, and the deep-water environment makes it difficult to effectively control the elevation and flatness of the underwater foundation. Direct lowering operations without node control can lead to the artificial reef deviating and tilting upon landing, resulting in uneven stress on the bottom and collision damage between adjacent reefs; in addition, the hoisting system without load-bearing capacity verification faces the risk of anchor dragging or sling breakage under dynamic loads, making it difficult to meet the design requirements of tightly arranged groups of ecological artificial reefs and the stability of the entire construction process.

[0005] To address the above problems, the present invention provides the following technical solution: This invention provides a method for the stable installation of concrete ecological artificial reefs at sea, comprising the following steps: The underwater foundation bed was explored using a measurement system, and a long-arm excavator was controlled to level and re-measure the top surface of the underwater foundation bed. After leveling and re-measurement, the anchor boat was used to assist the water crane vessel in positioning, and the transport ship transported the concrete ecological fish reef to one side of the water crane vessel. The main winch is controlled to lower the special hoisting device to connect the concrete ecological reef, and then the reef is lifted off the transport ship for a trial lift to check the stress state of the wire rope, the special hoisting device, and the concrete ecological reef. After the trial lifting is successful, the concrete ecological reef is lifted, and the position of the floating crane is adjusted by coordinating the raising and lowering of the anchor chain through the positioning winch. The concrete ecological reef is then moved above the target placement area, and the main winch is controlled to lower the concrete ecological reef to the underwater foundation. After the concrete ecological artificial reef touches the bottom, it remains suspended. Underwater detection equipment is used to check the placement posture and stability. Once the inspection is passed, the suspension connection is released, and adjacent concrete ecological artificial reefs are placed in the design sequence to form an ecological artificial reef group unit. The ecological artificial reef group unit is then retested.

[0006] Furthermore, the control of the long-arm excavator is to level and re-measure the top surface of the underwater foundation, including rough leveling and fine leveling; The rough leveling includes: The boom of the long-arm excavator is lowered to the top surface of the underwater foundation. The bucket and leveling scraper on the long-arm excavator are used to level the overly high protruding rocks and move them to a low-lying location. The top surface of the underwater foundation is scraped and the irregular stones are adjusted to modify the slope of the underwater foundation according to the designed slope ratio.

[0007] Furthermore, the specific steps of fine leveling include: A scale is set on the boom of the long-arm excavator, and a measurement is taken after the rough leveling is completed. The remeasured data is then compared with the design elevation. By combining the acquired real-time water level data and the scale on the boom, the length of the boom entering the water is corrected, and the lowering depth of the leveling scraper is controlled according to the elevation comparison result, so as to perform fine leveling on the top surface of the underwater base bed. For areas that are too high, scrape them off again; for areas that are too low, add stones and then level them again.

[0008] Furthermore, prior to the step of using an anchor boat to assist the floating crane vessel in positioning, a step of verifying the mass of a single anchor is also included: The anchor weight coefficient is determined based on the type of engineering vessel and the seabed of the construction area. The mass of a single anchor is calculated by combining the projected area of ​​each part above the full load waterline of the floating crane vessel on the longitudinal section of the ship, the width of the floating crane vessel, and the full load draft of the floating crane vessel. After the floating crane vessel arrives at the site, the anchor, anchor chain, positioning winch, main winch, hook, and braking device are inspected.

[0009] Furthermore, the step of lifting the concrete ecological artificial reef off the transport vessel for a trial lift to check the stress state of the wire rope, the special lifting device, and the concrete ecological artificial reef includes: Rubber pads are laid at the contact points between the special hanging device and the concrete ecological reef; The main winch is controlled to lift at a set speed. When the concrete ecological reef is detached from the deck of the transport ship and reaches the test lifting height, the lifting is paused to check the stress state of the special hoisting device and the balance state of the concrete ecological reef. When the concrete ecological reef tilts or the slings are under uneven stress, the concrete ecological reef is lowered onto the deck of the transport ship and adjusted.

[0010] Furthermore, before the step of controlling the main winch to lift at a set speed, the load-bearing capacity of the wire rope is verified, and the wire rope is the main hoisting wire rope; Based on the total lifting weight formed by the concrete ecological reef and the special lifting device, the number of slings, the angle between the slings and the horizontal plane, and the lifting safety factor, the minimum breaking tensile force of the main lifting wire rope is calculated and determined. The main lifting wire rope shall be selected with a minimum breaking strength not lower than the calculated result, and the condition of the main lifting wire rope and the connection status of the shackle, hook and the special lifting device shall be checked before each lifting operation.

[0011] Furthermore, the step of moving the concrete ecological reef to above the target placement area and then controlling the main winch to lower the concrete ecological reef to the underwater substrate includes: During the relocation process, the positioning winches are coordinated to evenly raise and lower the anchor chain, so that the concrete ecological reef and the hull of the water crane vessel are kept at a distance. After the floating crane vessel moves to above the target placement area, it controls the main winch to lower the concrete ecological reef, and uses the underwater detection equipment to monitor the lowering depth and position. The concrete ecological reef is lowered to a stop when it approaches the underwater substrate, so that the concrete ecological reef remains suspended.

[0012] Furthermore, following the step of keeping the concrete eco-reef hovering, the method further includes: While hovering, the landing point of the concrete ecological reef is verified based on data provided by the GPS positioning device and the underwater detection device; Once the landing point matches the design location, the main winch is controlled to slowly lower the concrete ecological reef until it contacts the top surface of the underwater foundation. During the lowering process, the main winch is kept running continuously.

[0013] Furthermore, the release of the suspension connection includes: After the concrete ecological reef comes into contact with the top surface of the underwater foundation, the main winch is braked to keep the special hoisting device in a suspended state and stationary. During the settling period, the underwater detection equipment was used to observe the placement posture of the concrete ecological reef and the settlement of the underwater foundation. After the concrete ecological artificial reef is placed and stabilized, the main winch is controlled to loosen the steel wire rope, so that the special hanging device is gradually unloaded. The connection between the special hanging device and the concrete ecological artificial reef is disconnected through the unloading mechanism, and the steel wire rope is kept slack during the unloading process. After unloading is completed, the main winch is controlled to retrieve the special hoisting device.

[0014] Furthermore, the process of grouping adjacent concrete ecological artificial reefs into ecological artificial reef cluster units according to the design sequence, and then retesting the ecological artificial reef cluster units, includes: The concrete ecological fish reefs are placed sequentially according to the design direction, so that adjacent concrete ecological fish reefs are closely attached to each other. After each set of concrete ecological artificial reefs is installed, the arrangement, flatness, and stability of the concrete ecological artificial reefs are checked using the underwater detection equipment. After all the concrete ecological artificial reefs have been installed, measure their actual positions, draw a plan of the reef group, and record the positions of the corners and the center of the reef group.

[0015] This invention provides a method for the stable offshore hoisting and construction of concrete ecological artificial reefs. It has the following beneficial effects: 1. This invention utilizes a measurement system to explore the underwater foundation bed and controls a long-arm excavator to perform rough and fine leveling operations on the top surface of the foundation bed by combining the boom scale with real-time water level data. This reduces the misalignment and steep slopes on the top surface of the foundation bed, providing a flat stress base for the placement of concrete ecological artificial reefs and avoiding engineering problems such as tilting or localized stress concentration after the artificial reefs hit the bottom.

[0016] 2. Before hoisting, this invention calculates and verifies the anchor mass based on the type of engineering vessel, full-load draft parameters, and seabed geology. It also calculates the minimum breaking strength of the main hoisting wire rope based on the total hoisting weight and the sling angle. By limiting the positioning conditions of the water crane vessel and the sling load-bearing threshold through objective parameters, this invention restricts the risk of the working vessel dragging anchor and the breakage of the hoisting sling, thus ensuring the reliability of the equipment throughout the entire hoisting process.

[0017] 3. This invention constructs a phased hoisting and static unloading process. In the initial stage of hoisting, the balance is checked by trial hoisting. When lowered to near the target position, it is kept suspended to verify the landing point. After the artificial reef touches the bottom and is statically observed, the steel wire rope is released to disconnect the connection. This reduces the landing deviation caused by water surface fluctuations, reduces the risk of structural collision, and meets the design requirements of the ecological artificial reef group units being closely attached. Attached Figure Description

[0018] Figure 1 This is a system framework diagram of the present invention; Figure 2 This is a flowchart of the method of the present invention; Figure 3 This is a flowchart of the underwater bed leveling operation of the present invention; Figure 4 This is a flowchart illustrating the process of fixed-point positioning of construction vessels and transportation of concrete ecological artificial reefs according to the present invention. Figure 5 This is a flowchart of the concrete ecological fish reef hanging and trial hanging inspection process of the present invention; Figure 6 This is a flowchart illustrating the stable lifting and placement process of the concrete ecological artificial reef according to the present invention. Figure 7 This is a flowchart illustrating the process of removing and grouping concrete ecological artificial reefs according to the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] See attached document Figure 1 This invention provides a system for the stable offshore hoisting and construction of concrete ecological artificial reefs, including a water crane vessel, anchor boat, transport vessel, long-arm excavator, special hoisting device and measurement system.

[0021] The floating crane vessel is equipped with a main winch, a positioning winch, and an anchoring system. The anchoring system includes an anchor chain and an anchor, which secures the floating crane vessel to the construction area. The positioning winch adjusts the position of the floating crane vessel by raising and lowering the anchor chain, while the main winch controls the lifting and lowering of the specialized hoisting device and the concrete ecological artificial reef.

[0022] Anchor boats work in conjunction with water crane vessels to complete anchor deployment, anchor position adjustment, fixed-point positioning, and anchor retrieval.

[0023] The transport vessel is used to transport the precast concrete eco-reefs, which have reached the designed strength, to the construction area. After the floating crane vessel is positioned, the transport vessel moors alongside it, allowing the concrete eco-reefs to be lifted to enter the working radius of the floating crane vessel.

[0024] The long-arm excavator is equipped with a bucket and a leveling scraper. The bucket is used to move the boulders on the top surface of the underwater subgrade, while the leveling scraper is used to push and scrape the top surface of the underwater subgrade to adjust the distribution of boulders and the elevation of the subgrade.

[0025] The specialized hoisting device is connected to the floating crane vessel via steel wire ropes. Rubber pads and a release mechanism are installed at the contact points between the specialized hoisting device and the concrete reef. The rubber pads isolate the specialized hoisting device from the concrete reef, and the release mechanism is used to disengage the hoisting connection after the concrete reef is in place.

[0026] The measurement system includes GPS positioning equipment and underwater detection equipment. The GPS positioning equipment is installed on the construction vessel to provide the vessel's coordinate data. The underwater detection equipment is used to measure the elevation of the underwater foundation surface and to check the underwater placement, flatness, and stability of the concrete ecological reef.

[0027] The underwater crane boat, anchor boat, transport ship, long-arm excavator, special lifting device and measurement system work together to complete the underwater foundation leveling, ship positioning, concrete ecological reef transportation, lifting and trial lifting, horizontal lowering, lifting equipment unloading and underwater re-measurement.

[0028] The concrete ecological artificial reefs are precast reinforced concrete structures. Multiple concrete ecological artificial reefs are arranged according to the design to form an ecological reef cluster unit, which is then placed on the top surface of the anchor platform. The top surface of the anchor platform constitutes the underwater placement base for the concrete ecological artificial reefs.

[0029] See attached document Figure 2 This invention provides a method for the stable installation of concrete ecological artificial reefs at sea, comprising the following steps: S100 uses a measurement system to explore the underwater foundation bed, controls a long-arm excavator to perform rough and fine leveling of the top surface of the underwater foundation bed, and performs a re-measurement after leveling is completed.

[0030] After the underwater foundation bed is leveled (S200), the anchor boat assists the water crane vessel in anchoring and positioning. The transport vessel delivers the concrete ecological reef to one side of the water crane vessel and completes berthing. Construction personnel then check the working status of the water crane vessel, transport vessel, special lifting equipment, and measurement system.

[0031] S300 controls the main winch to lower the special lifting device, connecting it to the concrete ecological reef. The concrete ecological reef is then lifted off the transport ship's deck for a trial lift to check the stress state of the wire rope, the special lifting device, and the concrete ecological reef.

[0032] After the S400 trial lift is successful, the concrete ecological reef is lifted and transported to the ship's side working area. Using a positioning winch to coordinate the raising and lowering of the anchor chain, the position of the surface crane is adjusted, and the concrete ecological reef is moved above the target placement area before being lowered into the underwater foundation.

[0033] After the S500 concrete ecological reef touches the bottom, it remains suspended. Underwater detection equipment is used to check the placement, attitude, and stability of the concrete ecological reef. Once the inspection is passed, the suspension connection is released, and adjacent concrete ecological reefs are placed in groups according to the designed arrangement. The completed ecological reef group units are then re-measured.

[0034] See attached document Figure 3 Step S100 includes the following sub-steps: S110: A work vessel equipped with a long-arm excavator enters the underwater foundation leveling area, with an anchor boat assisting in anchoring and securing the vessel. GPS positioning equipment is used to determine the construction location, ensuring the work vessel remains stationary during leveling. After the vessel is stationary, underwater detection equipment is used to scan the initial state of the underwater foundation, obtaining the actual elevation data of the top of the riprap. Areas with significant elevation differences are recorded, and the leveling sequence is determined based on the measurement results.

[0035] S120: Lower the boom of the long-arm excavator to the top surface of the underwater subgrade, and control the working depth according to the design elevation. Use the bucket and leveling scraper to handle areas with significant elevation differences, leveling and moving overly high protruding stones to lower-lying locations. Then, scrape and level the top surface of the underwater subgrade, adjusting the placement of irregular stones to ensure large stones are placed flat and stable, and trim the underwater subgrade slope according to the design slope ratio to complete the rough leveling.

[0036] S130, a scale is set on the boom of the long-arm excavator. After rough leveling, measurements are taken again, and the remeasured data is compared with the design elevation. The long-arm excavator operator, combining real-time water level data and boom scale, adjusts the boom's submersion length and controls the lowering depth of the leveling scraper based on the elevation comparison results to perform fine leveling of the underwater subgrade surface.

[0037] After the S140 leveling is completed, underwater detection equipment is used to re-measure the top surface of the underwater foundation section by section. Areas that are too high are scraped again, and areas that are too low are reinforced with boulders and then leveled again to eliminate any misalignments or steep slopes on the top surface of the underwater foundation.

[0038] The underwater subgrade leveling area covers the bottom outline of the concrete ecological reef placement area. Areas where the re-measurement results do not meet the design requirements are re-trimmed until the concrete ecological reef placement conditions are met. After leveling, the elevation of the underwater subgrade top surface and the leveling range are recorded. The long-arm excavator retracts its boom and secures the bucket and leveling scraper, and the work vessel carrying the long-arm excavator departs from the lifting operation area.

[0039] See attached document Figure 4 Step S200 includes the following sub-steps: S210: The surface crane vessel, equipped with GPS positioning equipment, enters the construction site and verifies the location. Anchor boats assist the surface crane vessel in anchoring at the designated point. During anchoring, the tension of the steel cables and the anchoring angle are controlled to avoid areas where construction has already been completed. After anchoring, the anchor position is checked regularly to ensure the surface crane vessel is not dragging its anchor, and the movement of nearby anchored vessels is monitored.

[0040] S220, the mass of a single anchor must be verified before the surface crane vessel is positioned. The mass of a single anchor is calculated using the following formula: ; In the formula, The theoretical mass of a single anchor, expressed in kg; The anchor weight coefficient is determined based on the type of engineering vessel and the seabed conditions of the construction area. The projected area of ​​all parts of the water crane vessel above the full-load waterline on the longitudinal section of the ship midway, in meters. 2 ; The width of the water crane vessel is in meters (m). The draft of a water crane vessel at full load is measured in meters (m).

[0041] After the floating crane vessel arrives on site, the anchor, anchor chain, positioning winch, main winch, hook, and braking device are inspected. Before lifting, the site's wind force, wave height, visibility, and weather conditions are checked. Lifting operations commence only after all conditions meet the construction control requirements; lifting is halted if any condition fails to meet the construction control requirements.

[0042] When operations cease, if the concrete ecological reef has not yet left the transport ship's deck, it will be lowered onto the transport ship's deck and its transport and fixed state restored; if the concrete ecological reef has already been moved out of the area above the transport ship's deck, it will be lowered vertically onto the leveled underwater base bed, and the hoisting connection will be released after the concrete ecological reef has been placed and stabilized.

[0043] S230, the concrete ecological artificial reefs are poured and cured at the prefabrication yard. After the concrete ecological artificial reefs reach the design strength, their appearance, structural dimensions, and lifting points are inspected. The qualified concrete ecological artificial reefs are loaded onto the transport vessel according to the lifting sequence, with supports and restraints in place to prevent collisions and movement during transport.

[0044] The transport vessel carried the concrete ecological artificial reef to the construction site by waterway, moored alongside the already positioned floating crane vessel, and secured it with cables. After the transport vessel was secured, the deck of the transport vessel, the lifting operation range of the floating crane vessel, and the lowering channel of the special lifting device were inspected to confirm that the lifting conditions were met.

[0045] See attached document Figure 5 Step S300 includes the following sub-steps: S310, based on the quality and structural characteristics of the concrete ecological artificial reef, symmetrical lifting points are set up to control the main winch to lower the special lifting device, connecting the special lifting device to the concrete ecological artificial reef. Rubber pads are laid at the contact points between the special lifting device and the concrete ecological artificial reef to avoid collision damage during lifting. The special lifting device connects multiple concrete ecological artificial reefs at once, and the lifting is released after placement by the detachment mechanism.

[0046] S320, a trial lift is conducted before actual lifting. The main winch is controlled to lift at the set speed. After the concrete reef detaches from the transport ship's deck and reaches the trial lift height, lifting is paused to check the stress state of the special lifting device and the balance of the concrete reef. If the concrete reef tilts or the slings experience uneven stress, it is lowered back onto the transport ship's deck. The wire rope length and lifting point positions are adjusted, and a second trial lift is performed after adjustments are completed.

[0047] S330, verify the load-bearing capacity of the main lifting wire rope before hoisting. The minimum breaking strength of the main lifting wire rope is determined by the following formula: ; In the formula, This is the minimum breaking strength of the wire rope, expressed in kN. For the safety factor of hoisting; The total lifting weight of the concrete ecological artificial reef and the special lifting device is expressed in kN. This refers to the number of suspension cables; The angle between the sling and the horizontal plane.

[0048] Calculate the minimum breaking strength of the wire rope based on the total lifting weight, the number of slings, the sling angle, and the safety factor, and select a wire rope with a minimum breaking strength not lower than the calculated result. Before each lifting operation, inspect the wire rope for broken wires, wear, corrosion, flattening, and kinks, and check the connection status of shackles, hooks, and special lifting devices. Replace any unqualified parts before proceeding with the lifting operation.

[0049] See attached document Figure 6 Step S400 includes the following sub-steps: After the trial lift of S410 is successful, the main winch is controlled to continue lifting the concrete reef. Once the concrete reef is out of the space above the transport ship, the floating crane vessel is operated to begin the ship transfer operation. During the transfer, the anchor chains are evenly extended and retracted by the positioning winches, the position of the floating crane vessel is adjusted, and a distance is maintained between the concrete reef and the hull of the floating crane vessel.

[0050] S420: After the surface crane vessel moves above the target placement area, it controls the main winch to lower the concrete ecological reef. During the lowering process, underwater detection equipment monitors the depth and position of the concrete ecological reef. Lowering stops when the concrete ecological reef approaches the underwater foundation, keeping it suspended.

[0051] In a hovering state, the S430 system verifies the landing point of the concrete ecological reef based on data provided by GPS positioning and underwater detection equipment. Once the landing point matches the design location, the main winch is controlled to slowly lower the concrete ecological reef until it contacts the top surface of the underwater foundation. During the lowering process, the main winch is kept running continuously to avoid sudden stops, starts, and oblique pulls.

[0052] See attached document Figure 7 Step S500 includes the following sub-steps: S510: After the concrete ecological reef contacts the top surface of the underwater foundation, brake the main winch to keep the special hoisting device suspended and stationary. During this period, observe the placement posture of the concrete ecological reef and the settlement of the underwater foundation using underwater detection equipment. Once the concrete ecological reef is stable, loosen the wire rope with the main winch to gradually unload the special hoisting device. If the inspection reveals that the concrete ecological reef is tilted or unstable, maintain the hoisting connection, re-lift the concrete ecological reef, and adjust its placement position.

[0053] After the S520 special lifting device is unloaded, the detachment mechanism disconnects the special lifting device from the concrete ecological reef. During detachment, the wire rope is kept slack to avoid pulling on the already positioned concrete ecological reef. After detachment is complete, the main winch is used to retrieve the special lifting device. Once the special lifting device is retrieved to the water surface, the wire rope, shackles, hooks, and the special lifting device itself are inspected. After confirming that everything is in normal condition, the next lifting batch can begin.

[0054] S530: Concrete ecological reefs are installed sequentially according to the design direction, ensuring that adjacent concrete ecological reefs are closely attached. After each set of concrete ecological reefs is installed, underwater detection equipment is used to verify the arrangement, flatness, and stability of the reefs. Any concrete ecological reefs found to be tilted or not in the correct position are re-lifted and adjusted by a surface crane vessel.

[0055] After all the concrete ecological artificial reefs are installed, the actual positions of the concrete ecological artificial reefs are measured, a plan of the reef group is drawn, and the positions of the corners and center of the reef group are recorded, forming underwater foundation measurement records, ship positioning records, trial lifting records, hoisting records, and underwater re-measurement records.

[0056] Specific application examples: The concrete ecological artificial reefs for this project are located at chainages from DD20+999 to DD22+400. The concrete ecological artificial reefs are constructed of C40 reinforced concrete, with each reef measuring 1.5m × 1.5m × 1.5m and weighing 1.8t.

[0057] The project involved the installation of 5,460 concrete ecological artificial reefs, divided into 78 ecological reef cluster units. Each ecological reef cluster unit comprises 70 concrete ecological artificial reefs, arranged in a pattern of 10 along the dike axis and 7 perpendicular to the dike axis. Adjacent concrete ecological artificial reefs were placed close together.

[0058] The construction project is divided into two working faces, each equipped with one water crane vessel and three transport vessels. The project involves a total of two water crane vessels, six transport vessels, one survey vessel, and two anchor boats.

[0059] Before placing the concrete ecological artificial reef, a long-arm excavator was used to level the top surface of the support platform. The excavator used its bucket and leveling scraper to move high-lying boulders to lower-lying areas, adjusted the placement of large boulders, and trimmed the slope according to the design ratio. After rough leveling, fine leveling was performed based on measurements. The leveling area covered the bottom outline of the concrete ecological artificial reef placement area.

[0060] After the water crane vessel enters the construction area, it is anchored at a fixed point with the assistance of an anchoring boat. In this embodiment, the water crane vessel is modeled as a crane vessel, the seabed of the construction area is hard mud and sandy mud, and the anchor weight coefficient is... Take 3.5; Width of the water crane boat 18m; Fully loaded draft It is 1.9m; ​​the projected area of ​​all parts above the full load waterline on the longitudinal section of the ship midway. It is 79.2m 2 .

[0061] Substitute the parameters into the formula: ; The theoretical mass of a single anchor was calculated to be 2072.7 kg. However, in actual construction, anchors with a single mass of 7000 kg were used, meaning the actual mass of the anchors used exceeded the theoretically calculated mass.

[0062] After the floating crane vessel is positioned, the anchor, anchor chain, positioning winch, main winch, hook, and braking device are inspected. In this embodiment, lifting operations are carried out when the visibility is not less than 1000m, the wave height is not greater than 2m, and the wind force is below level 6; lifting operations are suspended when the wind force reaches level 6, or when there is heavy rain or thunderstorms.

[0063] Once the concrete ecological artificial reef reaches 100% of its design strength, it is transported to the construction site by a transport ship. The transport ship is moored alongside the floating crane vessel and secured, allowing the concrete ecological artificial reef to be lifted into the working radius of the floating crane vessel.

[0064] Each standard hoisting batch consists of four concrete eco-reefs. Each placement row comprises ten concrete eco-reefs. Two standard hoisting operations are completed first, followed by the final hoisting operation to place the remaining two concrete eco-reefs.

[0065] A trial lift should be conducted before actual lifting. The lifting speed of the main winch should be controlled within 0.5 m / s. Lifting should be stopped 10 cm to 20 cm away from the transport ship deck to check the stress state of the special lifting device and the balance state of the concrete reef.

[0066] In a standard lifting batch, four concrete eco-reefs were lifted at once. Each concrete eco-reef weighs 1.8 tons, and the specialized lifting device weighs 1 ton, for a total weight of 8.2 tons for the four reefs and the device. Under the operating radius of the crane boom used in this lifting operation, the rated lifting capacity of the surface crane vessel is 15 tons, and the total lifting weight is less than the rated lifting capacity for this specific operating condition.

[0067] The minimum breaking strength of the main lifting wire rope is calculated according to the following formula: ; In the formula, For the safety factor of hoisting, we take 8; The total lifting weight of the four concrete ecological artificial reefs and the special lifting device is expressed in kN. The number of suspension cables is 2; The angle between the sling and the horizontal plane is 45°.

[0068] The construction used 6×36WS+IWR steel core wire rope with a diameter of 26mm and a nominal tensile strength of 1960N / mm². 2The minimum breaking tensile force is 472kN, which is greater than the calculated 454.6kN, thus meeting the lifting requirements. The main lifting wire rope is connected to the lifting hook and special lifting device of the water crane vessel via a G2160 bow shackle.

[0069] After the trial lift was successful, the main winch continued to lift the concrete reef. During the vessel relocation process, the positioning winch evenly extended and retracted the anchor chain, maintaining a distance of no less than 1 meter between the concrete reef and the hull of the floating crane vessel.

[0070] After the floating crane vessel reaches the target placement area, the main winch lowers the concrete ecological reef. Lowering stops when the concrete ecological reef is 1 meter away from the designed placement position on the underwater foundation, and the landing point is verified using positioning data.

[0071] After the landing point is verified, the main winch continues to lower the concrete ecological reef at a speed not exceeding 0.3 m / s until it contacts the top surface of the underwater foundation.

[0072] After the concrete ecological reef touches the bottom, it is left to stand for 30 seconds. Underwater detection equipment is used to check the placement posture of the concrete ecological reef and the settlement of the underwater foundation. After the concrete ecological reef is stable, the main winch releases the wire rope, and the unloading mechanism disconnects the suspension connection. At least 5 safety turns of wire rope are left on the main winch drum.

[0073] The ecological artificial reef units are constructed in a unidirectional sequence from north to south, perpendicular to the dike axis. The outer walls of adjacent concrete ecological artificial reefs are close together, and the distance between the edge of the concrete ecological artificial reef unit and the edge of the toe platform is not less than 2m.

[0074] After each set of concrete ecological reefs is installed, its flatness and stability are checked using underwater detection equipment. Any tilted concrete ecological reefs are lifted and adjusted. Once all concrete ecological reefs are installed, their actual locations are measured and a plan of the ecological reef group is drawn.

Claims

1. A method for the stable offshore hoisting construction of a concrete ecological artificial reef, characterized in that, Includes the following steps: The underwater foundation bed was explored using a measurement system, and a long-arm excavator was controlled to level and re-measure the top surface of the underwater foundation bed. After leveling and re-measurement, the anchor boat was used to assist the water crane vessel in positioning, and the transport ship transported the concrete ecological fish reef to one side of the water crane vessel. The main winch is controlled to lower the special hoisting device to connect the concrete ecological reef, and then the reef is lifted off the transport ship for a trial lift to check the stress state of the wire rope, the special hoisting device, and the concrete ecological reef. After the trial lifting is successful, the concrete ecological reef is lifted, and the position of the floating crane is adjusted by coordinating the raising and lowering of the anchor chain through the positioning winch. The concrete ecological reef is then moved above the target placement area, and the main winch is controlled to lower the concrete ecological reef to the underwater foundation. After the concrete ecological artificial reef touches the bottom, it remains suspended. Underwater detection equipment is used to check the placement posture and stability. Once the inspection is passed, the suspension connection is released, and adjacent concrete ecological artificial reefs are placed in the design sequence to form an ecological artificial reef group unit. The ecological artificial reef group unit is then retested.

2. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 1, characterized in that, The control of the long-arm excavator to level and re-measure the top surface of the underwater foundation includes rough leveling and fine leveling; The rough leveling includes: The boom of the long-arm excavator is lowered to the top surface of the underwater foundation. The bucket and leveling scraper on the long-arm excavator are used to level the overly high protruding rocks and move them to a low-lying location. The top surface of the underwater foundation is scraped and the irregular stones are adjusted to modify the slope of the underwater foundation according to the designed slope ratio.

3. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 2, characterized in that, The specific steps of fine leveling include: A scale is set on the boom of the long-arm excavator, and a measurement is taken after the rough leveling is completed. The remeasured data is then compared with the design elevation. By combining the acquired real-time water level data and the scale on the boom, the length of the boom entering the water is corrected, and the lowering depth of the leveling scraper is controlled according to the elevation comparison result, so as to perform fine leveling on the top surface of the underwater base bed. For areas that are too high, scrape them off again; for areas that are too low, add stones and then level them again.

4. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 1, characterized in that, Before the step of using an anchor boat to assist the water crane vessel in positioning, the method also includes a step of verifying the mass of a single anchor: The anchor weight coefficient is determined based on the type of engineering vessel and the seabed of the construction area. The mass of a single anchor is calculated by combining the projected area of ​​each part above the full load waterline of the floating crane vessel on the longitudinal section of the ship, the width of the floating crane vessel, and the full load draft of the floating crane vessel. After the floating crane vessel arrives at the site, the anchor, anchor chain, positioning winch, main winch, hook, and braking device are inspected.

5. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 1, characterized in that, The step of lifting the concrete ecological artificial reef off the transport vessel for a trial lift to check the stress state of the wire rope, the special lifting device, and the concrete ecological artificial reef includes: Rubber pads are laid at the contact points between the special hanging device and the concrete ecological reef; The main winch is controlled to lift at a set speed. When the concrete ecological reef is detached from the deck of the transport ship and reaches the test lifting height, the lifting is paused to check the stress state of the special hoisting device and the balance state of the concrete ecological reef. When the concrete ecological reef tilts or the slings are under uneven stress, the concrete ecological reef is lowered onto the deck of the transport ship and adjusted.

6. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 5, characterized in that, Before the step of controlling the main winch to lift at a set speed, the load-bearing capacity of the wire rope is verified, and the wire rope is the main hoisting wire rope; Based on the total lifting weight formed by the concrete ecological reef and the special lifting device, the number of slings, the angle between the slings and the horizontal plane, and the lifting safety factor, the minimum breaking tensile force of the main lifting wire rope is calculated and determined. The main lifting wire rope shall be selected with a minimum breaking strength not lower than the calculated result, and the condition of the main lifting wire rope and the connection status of the shackle, hook and the special lifting device shall be checked before each lifting operation.

7. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 1, characterized in that, The step of moving the concrete ecological artificial reef to above the target placement area and then controlling the main winch to lower the concrete ecological artificial reef to the underwater substrate includes: During the relocation process, the positioning winches are coordinated to evenly raise and lower the anchor chain, so that the concrete ecological reef and the hull of the water crane vessel are kept at a distance. After the floating crane vessel moves to above the target placement area, it controls the main winch to lower the concrete ecological reef, and uses the underwater detection equipment to monitor the lowering depth and position. The concrete ecological reef is lowered to a stop when it approaches the underwater substrate, so that the concrete ecological reef remains suspended.

8. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 7, characterized in that, Following the step of keeping the concrete eco-reef hovering, the method further includes: While hovering, the landing point of the concrete ecological reef is verified based on data provided by the GPS positioning device and the underwater detection device; Once the landing point matches the design location, the main winch is controlled to slowly lower the concrete ecological reef until it contacts the top surface of the underwater foundation. During the lowering process, the main winch is kept running continuously.

9. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 1, characterized in that, The process of releasing the suspension connection includes: After the concrete ecological reef comes into contact with the top surface of the underwater foundation, the main winch is braked to keep the special hoisting device in a suspended state and stationary. During the settling period, the underwater detection equipment was used to observe the placement posture of the concrete ecological reef and the settlement of the underwater foundation. After the concrete ecological artificial reef is placed and stabilized, the main winch is controlled to loosen the steel wire rope, so that the special hanging device is gradually unloaded. The connection between the special hanging device and the concrete ecological artificial reef is disconnected through the unloading mechanism, and the steel wire rope is kept slack during the unloading process. After unloading is completed, the main winch is controlled to retrieve the special hoisting device.

10. The method for stable offshore hoisting construction of concrete ecological artificial reefs according to claim 1, characterized in that, The process involves placing adjacent concrete ecological artificial reefs in a group according to the design sequence to form an ecological artificial reef cluster unit, and then re-measuring the ecological artificial reef cluster unit, including: The concrete ecological fish reefs are placed sequentially according to the design direction, so that adjacent concrete ecological fish reefs are closely attached to each other. After each set of concrete ecological artificial reefs is installed, the arrangement, flatness, and stability of the concrete ecological artificial reefs are checked using the underwater detection equipment. After all the concrete ecological artificial reefs have been installed, measure their actual positions, draw a plan of the reef group, and record the positions of the corners and the center of the reef group.

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