Large caisson offshore long distance floating multi-tug towed marshalling method

Abstract

The application provides a large caisson offshore long-distance floating towing multi-tugboat towing marshalling method, which adopts a main tugboat and four auxiliary tugboats to form a formation; the main tugboat is located at the front of the formation to pull the caisson, and the auxiliary tugboats are distributed around the caisson to control the direction and posture of the caisson through pushing or side towing; the method includes four-stage marshalling conversion: from leaving the dock to the shallow water area, the main tugboat is hoisted and towed in cooperation with 2-4 auxiliary tugboats to control the range of the caisson through side towing and pushing; from the shallow water area to the deep water area, the main tugboat is hoisted and towed in the front, one auxiliary tugboat is stably towed in the rear, and the remaining auxiliary tugboats are on standby; from the deep water area to the shallow water area, the main tugboat is hoisted and towed in cooperation with the auxiliary tugboats on both sides through mixed marshalling of side towing and pushing, and the rear auxiliary tugboat is pushed; from the shallow water area to the bridge position, the four auxiliary tugboats are converted to push the caisson on both sides, and the main tugboat is released and leaves; through the multi-tugboat stage-by-stage cooperation, the method realizes the accurate control and safe positioning of the large caisson offshore long-distance floating.

Description

Technical Field

[0001] This application relates to the field of bridge engineering technology, specifically to the multi-tugboat towing construction technology for the long-distance floating transport of large caisson foundations on water, applicable to the foundation construction of extra-large bridges in deep water and complex water environments such as sea crossings and river crossings. Background Technology

[0002] In bridge construction, large caisson foundations are widely used in mega-bridge projects in deep water, rapid currents, and complex geological conditions due to their good integrity, strong load-bearing capacity, and excellent adaptability to water flow. With the continuous increase in bridge spans and water depths, the planar dimensions and self-weight of caisson foundations have significantly increased. Some caissons can weigh tens of thousands or even hundreds of thousands of tons. Their large draft and low freeboard make them significantly affected by environmental factors such as wind, waves, and currents, posing severe challenges to floating and precise positioning during construction.

[0003] Traditional construction methods often involve integral fabrication in dry docks, air-assisted buoyancy, or towing using the buoyancy of the caisson itself. However, when the size of the caisson exceeds conventional dimensions, a single tugboat or simple towing combination is insufficient to meet the requirements for maneuverability, stability, and safety during the floating process. Especially in narrow channels, shallow waters, turbulent currents, or complex waters with high traffic density, large caissons are highly susceptible to deflection, loss of control, or even collisions, significantly increasing construction risks.

[0004] Therefore, there is an urgent need to develop a multi-tugboat collaborative towing construction technology suitable for long-distance floating transport of large caissons at sea. By scientifically determining the number of tugboats, the grouping method, the distribution of towing force, and the control strategy, the navigation stability and maneuverability during the floating transport of caissons can be improved. Summary of the Invention

[0005] In view of the above practical problems and the shortcomings of existing technologies, the main technical problem to be solved by the present invention is to provide a method for the long-distance floating transport of large caissons at sea using multiple tugboats in a formation. The aim is to systematically solve the key technical problems of the formation and conversion of multiple tugboats in the floating transport of large caissons at sea, and to provide reliable technical support for the construction of deep-water bridge foundations.

[0006] To address the aforementioned technical problems, this application provides a method for long-distance floating transport of large caissons at sea using multiple tugboats in a convoy configuration, employing the following technical solution:

[0007] A method for long-distance floating transport of large caissons at sea using multiple tugboats in a coordinated formation, wherein the floating transport of each caisson is completed by a formation of multiple tugboats; the coordinated formation of multiple tugboats includes one main tugboat and four auxiliary tugboats.

[0008] The main tugboat is positioned at the front of the formation and is used to tow the caisson; the auxiliary tugboats are distributed around the caisson and are used to apply jacking or towing at different positions of the caisson. The direction and attitude of the caisson are controlled by the coordinated operation of at least two of the auxiliary tugboats.

[0009] The method includes the conversion of floating transport formations from dock to shallow water, from shallow water to deep water, from deep water to shallow water, and from shallow water to bridge site.

[0010] The floating transport formation from the dock to the shallow water area is converted into a formation of main tugboat towing and auxiliary tugboat towing. In the transition section from the dock area to the shallow water area, the main tugboat begins to intervene and connects to the towing point on the caisson through the rope. Two to four auxiliary tugboats are used to tow and push the caisson to keep it within a certain range.

[0011] The shallow water to deep water floating formation is converted into a long-distance towing formation with main tugboats and auxiliary tugboats lined up one after the other, with the caisson in the middle. The main tugboat lifts and tows the caisson in front, one of the auxiliary tugboats stabilizes the caisson behind, and the remaining auxiliary tugboats are put on standby.

[0012] The deep-water to shallow-water floating formation is converted into a mixed formation of main tugboat towing and auxiliary tugboat alongside towing. One of the auxiliary tugboats is used on each side of the caisson for alongside towing, and the auxiliary tugboat located behind the caisson approaches the caisson and pushes it.

[0013] The formation from the shallow water area to the bridge site is converted into a formation using auxiliary tugboats pushing the caisson. Four of the auxiliary tugboats are distributed on both sides of the caisson wall. The auxiliary tugboats push the caisson wall, and the main tugboat is released and leaves the formation.

[0014] In a preferred embodiment: the entire conversion process from docking to floating and assembling in shallow water is completed collaboratively by one main tugboat and four auxiliary tugboats; after the caisson is docked, the four auxiliary tugboats apply pushes on both sides of the caisson to adjust its course and attitude.

[0015] The four auxiliary tugboats are designated as the first tugboat, the second tugboat, the third tugboat, and the fourth tugboat. The first and third tugboats are located on the right side of the caisson, while the second and fourth tugboats are located on the left side of the caisson.

[0016] In a preferred embodiment: the conversion from docking to shallow water floating transport fleet includes the following steps:

[0017] Step 11: After the caisson is launched from the dock, the four auxiliary tugboats are used to push and stabilize the caisson in the center of the channel. The main tugboat intervenes and connects to the towing point in front of the caisson through the rope. The main tugboat begins to slowly tighten and increase the force on the rope, so that it is slowly released to the predetermined length of 100 meters.

[0018] Step 12: The main tugboat, along with the first, second, and fourth tugboats, stabilizes the caisson body, while the third tugboat is turned and moved to the right rear side of the caisson for mooring.

[0019] Step 13: The main tugboat, along with the first, second, and third tugboats, stabilizes the caisson body, while the fourth tugboat is turned and moved to the left rear side of the caisson for mooring.

[0020] Step 14: Use the main tugboat, the third tugboat, and the fourth tugboat to stabilize the main body of the caisson. The second tugboat withdraws from the formation, and the first tugboat turns and moves to the rear of the caisson to moor its cables, forming a combination in which the main tugboat pulls from the front and the first tugboat pushes from the rear.

[0021] In a preferred embodiment: the conversion of the floating transport fleet from shallow water to deep water includes the following steps:

[0022] Step 21: The main tugboat maintains dominant traction, the third and fourth tugboats stabilize the caisson, and the first tugboat directly behind the caisson slowly decelerates and increases the distance between it and the rear of the caisson to 30 meters.

[0023] Step 22: The first tugboat controls the caisson from the rear and works with the main tugboat to stabilize its course. After the third and fourth tugboats release their mooring lines, they withdraw from the formation and stand by.

[0024] In a preferred embodiment: the conversion of the floating transport fleet from deep water to shallow water includes the following steps:

[0025] Step 31: The main tugboat and the first tugboat maintain the stability and course of the caisson, while the third and fourth tugboats, which were previously withdrawn, move to the right rear and left rear of the caisson, respectively, and reconnect with the restraint cables to the caisson.

[0026] Step 32: The main tugboat, the third tugboat, and the fourth tugboat work together to stabilize the caisson, while the first tugboat accelerates forward and moves close to the stern of the caisson.

[0027] In a preferred embodiment: the shallow water area to bridge site grouping conversion includes the following steps:

[0028] Step 41: The main tugboat, together with the first, third, and fourth tugboats, stabilizes the caisson, while the second tugboat, which is on standby, slowly approaches and is moored to the left front side of the caisson by pushing.

[0029] Step 42: The main tugboat, along with the second, third, and fourth tugboats, stabilizes the caisson. The first tugboat releases its mooring line from the rear of the caisson. After detaching, the first tugboat moves to the right front side of the caisson and moors itself to the right front side of the caisson by pushing.

[0030] Step 43: The main tugboat, together with the first tugboat, the second tugboat, and the third tugboat stabilizes the caisson. The fourth tugboat releases the mooring line on the left rear side of the caisson, turns and moves to the left rear side of the caisson, and moors itself to the left rear side of the caisson by pushing.

[0031] Step 44: The main tugboat, together with the first tugboat, the second tugboat, and the fourth tugboat, stabilizes the caisson. The third tugboat releases the mooring line on the right rear side of the caisson, turns and moves to the right rear side of the caisson, and moors itself to the right rear side of the caisson by pushing.

[0032] Step 45: The first tugboat, the second tugboat, the third tugboat and the fourth tugboat stabilize the caisson, the main tugboat is released from the towing point in front of the caisson, the main tugboat leaves the formation, and the caisson is completely taken over by the first tugboat, the second tugboat, the third tugboat and the fourth tugboat.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. Multi-tugboat collaborative formation construction technology: Based on sea conditions and navigation stages, this invention designs a four-stage formation conversion strategy. In narrow channels and shallow waters, multi-tugboat collaborative formation is used to ensure the stability of caisson towing and navigation safety; in deep waters, it switches to a two-tugboat formation to significantly improve floating efficiency.

[0035] 2. Significantly reduced safety risks: In high-risk waters such as narrow channels, shallow waters, and areas with dense bridge sites, the coordinated formation of multiple tugboats can effectively control the floating attitude of the caisson, prevent deflection, loss of control or collision, and greatly improve the level of construction and navigation safety.

[0036] 3. High adaptability and flexible operation: The grouping and conversion method proposed in this invention can be adjusted according to different water conditions and caisson structure characteristics, and has good engineering adaptability and on-site operability. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the tugboat position in step 11 of the present invention, which involves the conversion of the tugboat from the dock to the shallow water area for floating transport and formation.

[0038] Figure 2 This is a schematic diagram of the tugboat position in step 12 of the present invention, which involves the conversion of the tugboat from the dock to the shallow water area for floating transport and formation.

[0039] Figure 3 This is a schematic diagram of the tugboat position in step 13 of the present invention, which involves the conversion of the tugboat from dock to shallow water floating transport formation.

[0040] Figure 4 This is a schematic diagram of the tugboat position in step 14 of the present invention, which involves the floating and transporting of the vessel from the dock to the shallow water area.

[0041] Figure 5This is a schematic diagram of the tugboat positions in step 21 of the floating transport formation conversion from shallow water to deep water in this invention.

[0042] Figure 6 This is a schematic diagram of the tugboat positions in step 22 of the floating transport formation conversion from shallow water to deep water in this invention.

[0043] Figure 7 This is a schematic diagram of the tugboat positions in step 31 of the deep-water to shallow-water floating transport formation conversion of the present invention.

[0044] Figure 8 This is a schematic diagram of the tugboat positions in step 32 of the deep-water to shallow-water floating transport formation conversion of the present invention.

[0045] Figure 9 This is a schematic diagram of the tugboat positions in step 41 of the shallow water to bridge site grouping conversion of the present invention.

[0046] Figure 10 This is a schematic diagram of the tugboat positions in step 42 of the shallow water to bridge site grouping conversion of the present invention.

[0047] Figure 11 This is a schematic diagram of the tugboat positions in step 43 of the shallow water to bridge site grouping and conversion process of the present invention.

[0048] Figure 12 This is a schematic diagram of the tugboat position in step 44 of the shallow water area to bridge site grouping and conversion in this invention.

[0049] Figure 13 This is a schematic diagram of the tugboat position in step 45 of the shallow water area to bridge site grouping and conversion process of the present invention. Detailed Implementation

[0050] The technical solutions of 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0051] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0053] The following is in conjunction with the appendix Figures 1-13 This application will be described in further detail.

[0054] A method for long-distance floating transport of large caissons at sea using a multi-tugboat towing formation is disclosed. The method employs a multi-tugboat coordinated formation, with each caisson's floating transport completed by a formation of multiple tugboats. The multi-tugboat coordinated formation includes one main tugboat and four auxiliary tugboats. The main tugboat is located at the front of the formation and is used to tow the caisson. The auxiliary tugboats are distributed around the caisson and are used to apply jacking or towing at different positions of the caisson. The direction and attitude of the caisson are controlled by the coordinated operation of at least two of the auxiliary tugboats.

[0055] This method divides the entire process of large caissons from undocking to their bridge site into four main stages: floating and assembly conversion from undocking to shallow water area, floating and assembly conversion from shallow water area to deep water area, floating and assembly conversion from deep water area to shallow water area, and assembly conversion from shallow water area to bridge site. The specific steps for each stage are as follows:

[0056] The transition from dock to shallow water area floating transport formation occurs when the caisson has just left the dock and entered a relatively narrow and shallow water channel. This transition is from "static mooring" to "safe and controllable dynamic navigation," laying a solid foundation for subsequent long-distance deep-water navigation. The formation transition from dock to shallow water area involves a main tugboat towing and auxiliary tugboats towing alongside. In the transition section from the dock to the shallow water area, the main tugboat begins to intervene, connecting to the towing point on the caisson via ropes. Two to four auxiliary tugboats are used for alongside towing and pushing to keep the caisson within a certain range.

[0057] The entire conversion process from undocking to floating and assembling in shallow water is completed collaboratively by one main tugboat and four auxiliary tugboats. The main tugboat provides the main forward propulsion. After the caisson is undocking, the four auxiliary tugboats apply pushes on both sides of the caisson to adjust its course and attitude. The four auxiliary tugboats are divided into a first tugboat, a second tugboat, a third tugboat, and a fourth tugboat. The first tugboat and the third tugboat are located on the right side of the caisson, and the second tugboat and the fourth tugboat are located on the left side of the caisson.

[0058] like Figures 1-4The conversion from docking to floating transport and formation in shallow water includes the following steps:

[0059] Step 11: The caisson is moved from the dock to the center of the channel, allowing the four auxiliary tugboats to initially apply force. After the caisson is undocking, the four auxiliary tugboats are used to push and stabilize the caisson in the center of the channel. After undocking, the main tugboat intervenes, connecting to the towing point in front of the caisson via a rope. The main tugboat begins to slowly tighten and increase the force on the rope, allowing it to be slowly released to the predetermined length of 100 meters (reference). Figure 1 );

[0060] This length is a calculated safety distance that ensures effective transmission of traction while providing sufficient buffer space for the caisson. Simultaneously, all the tugboats work together to ensure the caisson remains stable in the center of the channel.

[0061] Step 12: The main tugboat, along with the first, second, and fourth tugboats, stabilizes the caisson body. The third tugboat, which was initially positioned to the right rear, is then turned and moved to the right rear side of the caisson for mooring (see reference). Figure 2 A control point was added to the "right rear" of the caisson, which enhanced its ability to cope with the wind and waves on the right side, strengthened the control of the caisson on the right side and at the tail, and prepared for subsequent adjustments.

[0062] Step 13: The main tugboat, along with the first, second, and third tugboats, stabilizes the caisson body. The fourth tugboat, which was initially positioned to the right rear, is then turned and moved to the left rear side of the caisson for mooring (see reference). Figure 3 ); symmetrically, control points were also established on the left rear side, and a force was freed up. Thus, control points were established on both the left and right sides behind the caisson.

[0063] Step 14: Using the main tugboat, the third tugboat, and the fourth tugboat, stabilize the caisson body. The second tugboat withdraws from the formation, and the first tugboat turns and moves to the rear of the caisson to moor its cables, forming a combination where the main tugboat pulls from the front and the first tugboat pushes from the rear (see reference). Figure 4 This forms the final towing formation before heading to open water, greatly enhancing maneuverability and emergency braking capabilities in shallow waterways.

[0064] The conversion of the floating transport formation from shallow water to deep water transforms the formation from a "flexible defense" posture for dealing with restricted shallow water areas to a "highly efficient power" posture for long-distance towing in open deep water areas. The shallow-water to deep-water floating transport formation is converted into a formation with a main tugboat and auxiliary tugboats arranged in tandem for long-distance towing, with the caisson in the center. The main tugboat lifts and tows the caisson from the front, one of the auxiliary tugboats stabilizes the caisson from the rear, and the remaining auxiliary tugboats stand by.

[0065] like Figures 5-6The conversion of the floating transport fleet from shallow water to deep water includes the following steps:

[0066] Step 21: The main tugboat maintains dominant traction, and the main towing cable should be extended to the 100-meter length required by shallow water regulations to provide sufficient buffer; the third and fourth tugboats stabilize the caisson, and the first tugboat directly behind the caisson slowly decelerates, increasing the distance between it and the rear of the caisson to 30 meters (reference). Figure 5 The core control of the formation was safely and smoothly transferred from the auxiliary tugboats in multiple directions to the main tugboat and the first tugboat (directly behind) that was about to be positioned, in preparation for the liberation of the third and fourth tugboats.

[0067] Step 22: The first tugboat, under rear control, coordinates with the main tugboat to stabilize the course of the caisson. After confirming a smooth transfer of control and stable attitude, the third and fourth tugboats release their mooring lines and withdraw from the formation to await further orders (see reference). Figure 6 ).

[0068] The conversion of the deep-water to shallow-water floating transport formation involves changing the formation's posture from a "highly efficient and dynamic" posture adapted to long-distance navigation in open seas to a "flexible and defensive" posture designed to respond to complex near-shore currents and narrow channels. The deep-water to shallow-water floating transport formation is converted into a mixed formation of main tugboat towing and auxiliary tugboat alongside. One auxiliary tugboat is used on each side of the caisson for alongside towing, while another auxiliary tugboat located behind the caisson approaches and pushes it towards the caisson.

[0069] like Figures 7-8 The conversion of the floating transport fleet from deep water to shallow water includes the following steps:

[0070] Step 31: The main tugboat and the first tugboat maintain the stability and course of the caisson. The third and fourth tugboats, which had previously withdrawn, move to the right and left rear of the caisson, respectively, and reconnect with the restraint cables to the caisson (see reference). Figure 7 ).

[0071] Step 32: After the main tugboat, the third tugboat, and the fourth tugboat stabilize the caisson's attitude together, control the switch from the first tugboat to the third and fourth tugboats, so that the main tugboat, the third tugboat, and the fourth tugboat form a typical "triangle" stable layout in the shallow water area.

[0072] The first tugboat accelerated forward and moved close to the stern of the caisson (reference). Figure 8 This close-fitting maneuver involves turning / towing the first tugboat from behind into a moored guard vessel, ready to provide immediate and powerful power support in case of emergency, in order to prevent loss of control in narrow and shallow waterways.

[0073] The transition from the shallow water area to the bridge site involves a complete handover of towing power and control in the narrowest and most complex section of water, from the shallow water area to the final bridge site. This allows the 10,000-ton caisson to be freed from long-range towing and controlled with millimeter-level precision by multiple tugboats, preparing it for final sinking and landing. The transition from the shallow water area to the bridge site involves auxiliary tugboats pushing the caisson's sides. Four auxiliary tugboats are positioned on either side of the caisson, pushing against the side walls while the main tugboat detaches and leaves the convoy.

[0074] like Figures 9-13 The shallow water area to bridge site grouping conversion includes the following steps:

[0075] Step 41: The main tugboat, along with the first, third, and fourth tugboats, stabilizes the caisson. The second tugboat, which is on standby, slowly approaches and secures itself to the left front side of the caisson using a jacking motion (see reference). Figure 9 This creates a stable environment for the first trailer to be released from its restraints and moved to its new location.

[0076] Step 42: The main tugboat, along with the second, third, and fourth tugboats, stabilizes the caisson. The first tugboat releases its mooring line from the rear of the caisson. After detaching, the first tugboat moves to the right front side of the caisson and secures its mooring line to the right front side of the caisson using a pushing motion (see reference). Figure 10 This allows force to be transferred from the rear to the side.

[0077] Step 43: The main tugboat, along with the first, second, and third tugboats, stabilizes the caisson. The fourth tugboat releases the mooring line on the left rear side of the caisson, turns, and moves to the left rear side of the caisson, then moors itself to the left rear side of the caisson by pushing (see reference). Figure 11 ).

[0078] Step 44: The main tugboat, along with the first, second, and fourth tugboats, stabilizes the caisson. The third tugboat releases the mooring line on the right rear side of the caisson, turns, and moves to the right rear side of the caisson, then moors itself to the right rear side of the caisson by pushing it (see reference). Figure 12 ).

[0079] Step 45: The first, second, third, and fourth tugboats stabilize the caisson; the main tugboat is released from the forward towing point of the caisson; the main tugboat departs from the convoy; and the caisson is fully taken over by the first, second, third, and fourth tugboats (see reference). Figure 13 ).

[0080] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for long-distance floating transport of large caissons at sea using multiple tugboats in a tandem configuration, characterized in that: The floating and transport of each caisson is carried out by a multi-tugboat coordinated formation, which includes one main tugboat and four auxiliary tugboats. The main tugboat is positioned at the front of the formation and is used to tow the caisson; the auxiliary tugboats are distributed around the caisson and are used to apply jacking or towing at different positions of the caisson. The direction and attitude of the caisson are controlled by the coordinated operation of at least two of the auxiliary tugboats. The method includes the conversion of floating transport formations from dock to shallow water, from shallow water to deep water, from deep water to shallow water, and from shallow water to bridge site. The floating transport formation from the dock to the shallow water area is converted into a formation of main tugboat towing and auxiliary tugboat towing. In the transition section from the dock area to the shallow water area, the main tugboat begins to intervene and connects to the towing point on the caisson through the rope. Two to four auxiliary tugboats are used to tow and push the caisson to keep it within a certain range. The shallow water to deep water floating formation is converted into a long-distance towing formation with main tugboats and auxiliary tugboats lined up one after the other, with the caisson in the middle. The main tugboat lifts and tows the caisson in front, one of the auxiliary tugboats stabilizes the caisson behind, and the remaining auxiliary tugboats are put on standby. The deep-water to shallow-water floating formation is converted into a mixed formation of main tugboat towing and auxiliary tugboat alongside towing. One of the auxiliary tugboats is used on each side of the caisson for alongside towing, and the auxiliary tugboat located behind the caisson approaches the caisson and pushes it. The formation from the shallow water area to the bridge site is converted into a formation using auxiliary tugboats pushing the caisson. Four of the auxiliary tugboats are distributed on both sides of the caisson wall. The auxiliary tugboats push the caisson wall, and the main tugboat is released and leaves the formation.

2. The method for long-distance floating transport of large caissons at sea using multiple tugboats and assemblies, as described in claim 1, is characterized in that: The entire conversion process from the dock to the shallow water area for floating and grouping is completed by one main tugboat and four auxiliary tugboats working together. After the caisson is docked, the four auxiliary tugboats apply pushes on both sides of the caisson to adjust its course and attitude. The four auxiliary tugboats are designated as the first tugboat, the second tugboat, the third tugboat, and the fourth tugboat. The first and third tugboats are located on the right side of the caisson, while the second and fourth tugboats are located on the left side of the caisson.

3. The method for long-distance floating transport of large caissons at sea using multiple tugboats and assemblies, as described in claim 2, is characterized in that: The conversion from docking to shallow water floating transport fleet includes the following steps: Step 11: After the caisson is launched from the dock, the four auxiliary tugboats are used to push and stabilize the caisson in the center of the channel. The main tugboat intervenes and connects to the towing point in front of the caisson through the rope. The main tugboat begins to slowly tighten and increase the force on the rope, so that it is slowly released to the predetermined length of 100 meters. Step 12: The main tugboat, along with the first, second, and fourth tugboats, stabilizes the caisson body, while the third tugboat is turned and moved to the right rear side of the caisson for mooring. Step 13: The main tugboat, along with the first, second, and third tugboats, stabilizes the caisson body, while the fourth tugboat is turned and moved to the left rear side of the caisson for mooring. Step 14: Use the main tugboat, the third tugboat, and the fourth tugboat to stabilize the main body of the caisson. The second tugboat withdraws from the formation, and the first tugboat turns and moves to the rear of the caisson to moor its cables, forming a combination in which the main tugboat pulls from the front and the first tugboat pushes from the rear.

4. The method for long-distance floating transport of large caissons at sea using multiple tugboats and assemblies, as described in claim 3, is characterized in that: The conversion of the floating transport fleet from shallow water to deep water includes the following steps: Step 21: The main tugboat maintains dominant traction, the third and fourth tugboats stabilize the caisson, and the first tugboat directly behind the caisson slowly decelerates and increases the distance between it and the rear of the caisson to 30 meters. Step 22: The first tugboat controls the caisson from the rear and works with the main tugboat to stabilize its course. After the third and fourth tugboats release their mooring lines, they withdraw from the formation and stand by.

5. The method for long-distance floating transport of large caissons at sea using multiple tugboats as described in claim 4, characterized in that: The conversion of the floating transport fleet from deep water to shallow water includes the following steps: Step 31: The main tugboat and the first tugboat maintain the stability and course of the caisson, while the third and fourth tugboats, which were previously withdrawn, move to the right rear and left rear of the caisson, respectively, and reconnect with the restraint cables to the caisson. Step 32: The main tugboat, the third tugboat, and the fourth tugboat work together to stabilize the caisson, while the first tugboat accelerates forward and moves close to the stern of the caisson.

6. The method for long-distance floating transport of large caissons at sea using multiple tugboats as described in claim 5, characterized in that: The transition from shallow water area to bridge site grouping includes the following steps: Step 41: The main tugboat, together with the first, third, and fourth tugboats, stabilizes the caisson, while the second tugboat, which is on standby, slowly approaches and is moored to the left front side of the caisson by pushing. Step 42: The main tugboat, along with the second, third, and fourth tugboats, stabilizes the caisson. The first tugboat releases its mooring line from the rear of the caisson. After detaching, the first tugboat moves to the right front side of the caisson and moors itself to the right front side of the caisson by pushing. Step 43: The main tugboat, together with the first tugboat, the second tugboat, and the third tugboat stabilizes the caisson. The fourth tugboat releases the mooring line on the left rear side of the caisson, turns and moves to the left rear side of the caisson, and moors itself to the left rear side of the caisson by pushing. Step 44: The main tugboat, together with the first tugboat, the second tugboat, and the fourth tugboat, stabilizes the caisson. The third tugboat releases the mooring line on the right rear side of the caisson, turns and moves to the right rear side of the caisson, and moors itself to the right rear side of the caisson by pushing. Step 45: The first tugboat, the second tugboat, the third tugboat and the fourth tugboat stabilize the caisson, the main tugboat is released from the towing point in front of the caisson, the main tugboat leaves the formation, and the caisson is completely taken over by the first tugboat, the second tugboat, the third tugboat and the fourth tugboat.

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