Large prefabricated structure undocking method based on own traction system

Abstract

The invention discloses a large prefabricated structure undocking method based on an own traction system. The traction system comprises a winch and a steering saddle on the top of the prefabricated structure, a cable tying column on the top of the dock wall and a cable. At least four traction systems are arranged. The method comprises the following steps: step 1, for a traction system at the front part of a prefabricated structure, connecting a cable with cable tying columns on two sides closest to a dock entrance; for the traction system at the rear part, a cable is connected with the cable tying columns at the two sides at the rear part; 2, injecting water into the dock; during water injection, according to the height difference between the prefabricated structure and the top of the dock wall, all the sets of winches are started to take up and pay off the cable; 3, a winch is started to synchronously tighten the front mooring rope and synchronously release the rear mooring rope so as to pull the prefabricated structure to move to the dock entrance; 4, the left rear portion and the right rear portion of the prefabricated structure are connected with the adjacent cable tying columns through auxiliary ropes; connecting the rear cable to a cable tying column closer to the prefabricated structure; and then the auxiliary rope is removed.

Description

Technical Field

[0001] The invention relates to the technical field of offshore caisson construction, and in particular to a method for undocking a large prefabricated structure. Background Art

[0002] With the rapid development of construction technology in the infrastructure field, prefabricated structures such as large caissons and caissons have been widely used in various projects. Due to the characteristics of the project, the construction environment and other factors, some projects cannot manufacture these large prefabricated structures in the construction area, so they are often welded and assembled in the dry environment of the dock. After the large prefabricated structure is manufactured, water is poured into the dock to a sufficient height to make it float by opening the dock door. Then the tugboat enters the dock and uses the mooring posts and other structures of these large prefabricated structures to tow them and float them to the bridge site.

[0003] The above is the traditional construction method for undocking large prefabricated structures such as large caissons and caissons, which has the following shortcomings: (1) If the dock width is insufficient, it is impossible to arrange auxiliary tugs on the side of the large prefabricated structure, and it can only be towed by the main tug in front. Due to the lack of lateral constraints, the towed prefabricated structure may swing during movement, thereby colliding with the dock, causing damage to both the prefabricated structure and the dock; (2) When there is an auxiliary tug operating on the side, if the main tug in front is not operated properly, it is easy for the towed prefabricated structure to deviate from the predetermined track, and it may squeeze the auxiliary tug together with the dock wall, which will cause greater safety risks to the hull and construction personnel; (3) This construction method requires a large number of tugboats, and the rental cost is high; and this method has high requirements for the synchronization and coordination of construction, so it also requires more manpower. Summary of the invention

[0004] The main technical problem to be solved by the present invention is to provide a method for undocking a large prefabricated structure, which can stably and safely undock the prefabricated structure with a relatively low construction cost by utilizing its own traction system.

[0005] In order to solve the above technical problems, the present invention provides a method for undocking a large prefabricated structure based on a self-propelled traction system, based on the following hardware foundations:

[0006] The dock comprises a dock chamber, a dock wall and a dock opening; the dock wall extends on both sides of the dock chamber, and the dock opening is located at one end of the dock chamber close to the water area; the prefabricated structure is located in the dock chamber and undocking in the direction of the dock opening;

[0007] A traction system, comprising a winch, a steering saddle, a plurality of mooring posts and a cable; the winch is installed on a construction platform on the top of the prefabricated structure to retract and release the cable; the steering saddle is installed on the edge of the top of the prefabricated structure; the steering saddle is constructed with a trumpet-shaped cable passage, the trumpet of which faces the outside of the prefabricated structure; the plurality of mooring posts are installed on the top of the dock walls on both sides of the dock and are arranged at intervals along the extension direction of the dock walls; the cable comprises a first end and a second end, the first end is fixed to the winch, and the second end extends from the winch, passes through the cable passage of the steering saddle, and is finally connected to the mooring post;

[0008] At least four groups of the traction systems are arranged in the dock, including traction system A, traction system B, traction system C and traction system D; in the undocking direction of the prefabricated structure, the traction system A and traction system B are arranged at the front of the construction platform, and are located on the left and right sides respectively; the traction system C and traction system D are arranged at the rear of the construction platform, and are located on the left and right sides respectively;

[0009] The method comprises the following steps:

[0010] Step 1: Connect the cable; in traction system A, connect the cable to the left mooring post closest to the dock; in traction system B, connect the cable to the right mooring post closest to the dock; in traction system C, connect the cable to a mooring post behind the left side of the steering saddle; in traction system D, connect the cable to a mooring post behind the right side of the steering saddle;

[0011] Step 2: Filling water and floating up; filling water into the dock chamber until the water level meets the conditions for undocking; during the water filling process, each group of winches needs to be started to retract and release each group of cables according to the height difference between the prefabricated structure and the top of the dock wall;

[0012] Step 3: Towing out of the dock; for traction system A and traction system B, the winches in the system are turned on to synchronously tighten the two cables in the front. At the same time, for traction system C and traction system D, the winches in the system are turned on to synchronously release the two cables in the rear to tow the prefabricated structure to the dock.

[0013] In a preferred embodiment, after step 3, there is step 4: system transformation;

[0014] At least two auxiliary ropes are used to connect the left rear part and the right rear part of the prefabricated structure to the adjacent mooring posts respectively and tension them; then, in the traction system C, the second end of the rope is released from the original mooring post and connected to the adjacent mooring post at the left rear of the steering saddle; in the traction system D, the second end of the rope is released from the original mooring post and connected to the adjacent mooring post at the right rear of the steering saddle; further, the auxiliary rope is released.

[0015] In a preferred embodiment, in step 3, when the prefabricated structure approaches the dock, the rope-collecting rate of the winches in traction system A and traction system B and the rope-releasing rate of the winches in traction system C and traction system D are controlled to decelerate the prefabricated structure.

[0016] In a preferred embodiment, in step 3, the moving speed of the prefabricated structure is no more than 0.5 m / s.

[0017] In a preferred embodiment, in step 1, after the cables in each group of traction systems are correctly connected, each group of winches is started to tighten the cables.

[0018] In a preferred embodiment, in step 2, when the prefabricated structure floats up, each group of winches is started to coordinate the length of each group of cables to fine-tune the center line of the prefabricated structure to coincide with the center line of the dock chamber.

[0019] In a preferred embodiment, in step 2, the top of the prefabricated structure is higher than the top of the dock wall; during the water injection process, each group of winches is started to synchronously release each group of cables.

[0020] In a preferred embodiment, the direction in which the winch retracts and releases the cable is different from the extension direction of the cable channel in the steering saddle; the traction system also includes a reversing wheel; the reversing wheel is installed on the construction platform and is located near the intersection of the center lines of the winch and the steering saddle; the reversing wheel has rotational freedom in the horizontal plane; after the cable is led out from the winch, it is partially wrapped around the annular wheel and extends toward the steering saddle.

[0021] In a preferred embodiment, the steering saddle includes a bottom plate, side plates and a movable top plate; the bottom plate is trumpet-shaped and tilted or bent downward in the direction of the trumpet mouth; the two arc-shaped side plates are fixedly connected to the left and right sides of the bottom plate in the extension direction, and together with the top of the bottom plate, they construct a trumpet-shaped cable passage; the two side plates and the bottom of the bottom plate construct a support cavity, and the support cavity is filled with concrete; the side plate is fixedly connected to a stiffening frame on the side facing away from the cable passage; the movable top plate is detachably connected to the top of the stiffening frames on both sides to straddle the top of the cable passage.

[0022] In a preferred embodiment, the traction system also includes a rope loop and a shackle; the rope loop is connected end to end through the shackle and then mounted on the mooring post; the shackle can be opened and closed; the second end of the cable is provided with an annular rope loop; in steps 1 to 3, the cable is connected to the mooring post by passing the rope loop through the shackle.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] The method provided by the present invention uses the winch of the large prefabricated structure to retract and release the cable connected to the dock wall, and uses the principle of "action and reaction" between objects to safely and stably pull the prefabricated structure forward and out of the dock. This method uses the self-contained traction system to replace the tugboat, cleverly avoiding the problem of the prefabricated structure lateral squeezing the auxiliary tug due to improper main tug operation, limited space, etc., which not only improves construction safety, but also reduces rental cost investment.

[0025] Secondly, at least four traction systems work together at the four corners of the prefabricated structure to control the precise movement of the prefabricated structure in the four directions of front, back, left, and right, and to maintain dynamic balance. This method effectively solves the problem of the prefabricated structure swaying left and right and colliding with the dock wall due to the abandonment of lateral auxiliary towing in a narrow dock, and thus has high engineering applicability.

[0026] In addition, because this method can use the winch to accurately control the prefabricated structure, when encountering an emergency or approaching the destination, the prefabricated structure has a higher braking performance, which is lacking in most towing and undocking methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic plan view of the traction system in Embodiment 1 of the present invention installed on a steel caisson;

[0028] Figure 2 It is a schematic elevation view of the traction system in Embodiment 1 of the present invention installed on a steel caisson;

[0029] Figure 3 It is a plan view schematic diagram of the reversing wheel, the second base and the fixing frame described in Example 1 of the present invention;

[0030] Figure 4 It is a cross-sectional schematic diagram of the reversing wheel, the second base and the fixing frame described in Example 1 of the present invention;

[0031] Figure 5 It is a schematic plan view of the steering saddle described in Example 1 of the present invention;

[0032] Figure 6It is a schematic elevation view of the steering saddle described in Example 1 of the present invention;

[0033] Figure 7 It is a three-dimensional schematic diagram of the mooring bitt, rope loop and shackle described in Example 1 of the present invention;

[0034] Figure 8 It is a schematic diagram of the steel caisson in the initial position before being undocking in Example 1 of the present invention;

[0035] Fig. 9 It is a schematic diagram of the system conversion of the steel caisson at the dock entrance in Example 1 of the present invention;

[0036] Fig.10 It is a schematic diagram of the steel caisson in Example 1 of the present invention being moved to the docking port;

[0037] Fig.11 It is a plan view schematic diagram of the traction system described in Example 2 of the present invention installed on a steel caisson.

[0038] Markings in the figure are: 1- winch, 10- first base, 2- reversing wheel, 20- second base, 21- fixed frame, 211- fixed shaft, 212- limiting part, 3- steering saddle, 31- bottom plate, 311- grouting hole, 32- side plate, 321- stiffening frame, 33- movable top plate, 34- support cavity, 35- cable passage, 30- third base, 301- pier, 302- steel corbel, 4- mooring post, 41- column cap, 42- rope loop, 43- shackle, 5- cable, 51- first end, 52- second end, 53- rope loop, 6- steel caisson, 61- cofferdam, 62- construction platform, 7- dock, 71- dock room, 72- dock wall, 73- dock mouth, 8- fiber rope. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "installed / connected", "connected", etc. should be understood in a broad sense. 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 the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0042] Example 1

[0043] like Figures 1 to 10 As shown, the embodiment of the present invention provides a method for undocking a large prefabricated structure based on a self-powered traction system. In this embodiment, the prefabricated structure is a steel caisson 6.

[0044] First, the hardware basis of the method, namely the dock and the traction system, is explained with reference to the diagram. Figure 8 to Figure 10 As shown, the dock 7 includes a dock chamber 71, a dock wall 72, and a dock opening 73. The dock wall 72 extends on both sides of the dock chamber 71, and the dock opening 73 is located at one end of the dock chamber 71 close to the water area. The steel caisson 6 is located in the dock chamber 71 and is undocking in the direction of the dock opening 73. The traction system includes: a winch 1 installed on the top of the steel caisson 6, a reversing wheel 2, a steering saddle 3, a mooring post 4 arranged on the top of the dock wall 72, and a cable 5.

[0045] like Figure 1 , Figure 2 As shown, the winch 1 is installed on the construction platform 62 at the top of the steel caisson 6 through the first base 10. The first base 10 is a rigid spatial structure welded from a number of steel sections. The bottom of the first base 10 is welded to the construction platform 62, and an operating platform is provided on the top to fix the winch 1 and for the operator to stand. In this embodiment, the first steel section adopts double-pieced No. 25 I-beams, and the steel grade is 0235B. The first base 10 is 6.5 meters long, 3.5 meters wide, and 2.0 meters high. The maximum traction force of the winch 1 is 25 tons.

[0046] like Figure 1 to Figure 4As shown, the reversing wheel 2 is a groove fixed pulley, which is installed on the construction platform 62 through a fixing frame 21 and a second base 20. Similar to the first base 10, the second base 20 is a rigid space structure welded by a plurality of steel sections. The bottom of the second support is welded to the construction platform 62, and the fixing frame 21 is fixed to the top. The fixing frame 21 is a steel structure. In this traction system, the reversing wheel 2 is used to reverse the cable 5 in the horizontal direction. Therefore, the necessary structural features of the fixing frame 21 are: a fixed shaft 211 is provided in the vertical direction, and the reversing wheel 2 is sleeved on the fixed shaft 211 so that it has rotational freedom in the horizontal plane; secondly, the fixing frame 21 is provided with a limiting portion 212 at the bottom and top of the reversing wheel 2, and the limiting portion 212 is limitedly matched with the reversing wheel 2 in the vertical direction to prevent the reversing wheel 2 from being separated from the fixed shaft 211. In this embodiment, the second steel section is the same as the first steel section. The second base 20 is 2.0 meters long, 1.0 meters wide and 0.5 meters high. The diameter of the reversing wheel 2 is 70 centimeters.

[0047] like Figure 1 , Figure 5 and Figure 6As shown, the steering saddle 3 includes a bottom plate 31, a side plate 32 and a movable top plate 33. On the horizontal plane, the bottom plate 31 is trumpet-shaped, with a relatively wide flared opening and a relatively narrow closed opening; in the vertical direction, the bottom plate 31 gradually tilts or bends downward from a position close to the closed opening to the flared opening. Two arc-shaped side plates 32 are welded to the left and right sides of the extension direction of the bottom plate 31, and together with the top of the bottom plate 31, a trumpet-shaped cable passage 35 is constructed to position and guide the cable 5 when it is retracted. The trumpet mouth of the cable passage 35 faces the outside of the steel caisson 6. The two side plates 32 and the bottom of the bottom plate 31 construct a support cavity 34. In order to provide the bearing capacity and structural stability of the steering saddle 3, the support cavity 34 is filled with concrete, and correspondingly, a grouting hole 311 is provided on the bottom plate 31 to facilitate grouting. The side plate 32 is fixed with a stiffening frame 321 on the side facing away from the cable passage 35. The stiffening frame 321 is a rigid structure formed by staggered welding of several steel plates. When the working angle of the wire rope is large, the side plate 32 is bent outward by the wire rope. At this time, the vertical stiffening frame 321 can transfer part of the force to the steel caisson 6 to achieve force unloading. The movable top plate 33 is detachably connected to the top of the stiffening frames 321 on both sides through a bolt assembly to straddle the top of the cable passage 35. In this way, the cable passage 35 forms a closed loop on the vertical plane, limiting the cable 5 from flying out of the cable passage 35 from the top when passing quickly. In this embodiment, the steering saddle 3 is 1.9 meters long, 1.7 meters wide and 0.9 meters high. The bottom plate 31, side plate 32, stiffening frame 321 and movable top plate 33 are made of steel plates, and the steel grade is Q335. The concrete filled in the support cavity 34 is graded C30. In general, the steering saddle 3 adopts a trumpet-shaped structure, which can adapt to the cables 5 supported at multiple angles, creating a higher degree of flexibility for the undocking construction of the steel caisson 6; at the same time, this structure reduces the friction between the steel wire rope and makes the traction system run more smoothly.

[0048] like Figure 2As shown, the steering saddle 3 is fixed to the top of the cofferdam 61 (hereinafter referred to as "cofferdam 61") of the steel caisson 6 through the third base 30. The third base 30 includes a pier 301 and a steel corbel 302. The pier 301 is cast on the top of the cofferdam 61 with concrete, and its function is to connect the cofferdam 61 upward to the height of the construction platform 62, so that when the steering saddle 3 is installed on the pier 301, it is convenient to cooperate with the reversing wheel 2 in the horizontal direction. In order to facilitate the cable passing, the steering saddle 3 extends a distance to the outside of the cofferdam 61. Therefore, the steel corbel 302 is fixed to the outside of the pier 301. The steel corbel 302 is a rigid structure welded by a plurality of steel plates. The top of the steel corbel 302 is welded to the bottom of the steering saddle 3 to support the extended section of the latter. There are many ways to fix the steel corbel 302 to the pier 301. For example, the steel corbel 302 can be partially embedded in the pier 301; for another example, a connecting plate is embedded on the outside of the pier 301, and the steel corbel 302 is welded to the connecting plate; for another example, a steel structure box is wrapped outside the pier 301, and the steering saddle 3 is welded to the outside of the box. As a mature prior art, this article does not limit this connection method. In this embodiment, the steel corbel 302 is 2.6 meters long, 2.2 meters wide, and 1.8 meters high, and is welded with 30 mm thick Q355 steel plates.

[0049] like Figures 7-10 As shown, the mooring post 4 is fixed to the top of the dock wall 72 by a plurality of bolt assemblies. The mooring post 4 is provided with a column cap 41 for limiting. A rope loop 42 and a shackle 43 are also used in conjunction with the mooring post 4. The rope loop 42 adopts a steel wire rope with a diameter of 32 mm, and is connected end to end through the shackle 43 and then sleeved on the mooring post 4. The shackle 43 can be opened and closed, and is connected to the outside with a rope. In this embodiment, the maximum load capacity of the shackle 43 is 25 tons. In the extension direction of the dock wall 72, a plurality of the mooring posts 4 are arranged at intervals. The mooring posts 4 on the dock walls 72 on both sides of the dock 7 are symmetrically arranged about the center line of the dock 7.

[0050] The cable 5 is a steel wire rope with a diameter of 53 mm and a single length of 210 meters. For the convenience of description, the end of the cable 5 fixed on the steel caisson 6 is defined as the first end 51, and the other end is defined as the second end 52. Generally speaking, the first end 51 is fixed to the drum of the winch 1, and the second end 52 is led out from the winch 1, passes through the steering saddle 3, and extends out from the steel caisson 6. Figure 1As shown, similar to the layout shown in this embodiment, in some existing traction systems, in order to optimize the wiring of the power supply and streamline the configuration of the operators, multiple winches 1 are centrally installed near the middle of the construction platform 62. In this way, the retracting and releasing direction of the cable 5 by the winch 1 cannot be in line with the extension direction of the cable passage 35 on the steering saddle 3. In order to reduce the wear of the cable 5 and avoid the cable 5 from getting stuck, the reversing wheel 2 is arranged near the intersection of the center line of the winch 1 and the steering saddle 3. The cable 5 led out from the winch 1 is partially arranged on the reversing wheel 2, and its own extension direction is adjusted to the center line of the winch 1 and the steering saddle 3, reducing the friction with the winch 1 and the steering saddle 3, and realizing the smooth and stable operation of the traction system. It can be understood that due to the limitations of the on-site conditions, the actual routing of the cable 5 does not completely coincide with the center line of the winch 1 and the steering saddle 3, but as long as the deflection angle is controlled within a reasonable range, it will not affect the actual operation of the traction system.

[0051] In order to enable the steel caisson 6 to move in the extension direction of the dock 7, the second end 52 of the cable 5 extends from the steering saddle 3 and is connected to the mooring posts 4 on the dock walls 72 on both sides. Figure 1 As shown, the second end portion 52 is provided with an annular rope loop 53 to quickly and stably connect with the shackle 43 on the mooring post 4. For the convenience of the following description, the direction of the steel caisson 6 toward the dock opening 73 is defined as the front, and the direction away from the dock opening 73 is defined as the rear. The principle of the undocking method is that when the steel caisson 6 is in a floating state, the front cable 5 is symmetrically connected to the mooring posts 4 on both sides of the undocking direction of the steel caisson 6, and the front winch 1 is started to synchronously tighten the part of the cable 5, so that the steel caisson 6 can be pulled toward the dock opening 73 through the principle of "action and reaction" between the dock wall 72 and the steel caisson 6. During this process, in order to prevent the rear of the steel caisson 6 from swaying, the rear cable 5 is symmetrically connected and tensioned with the mooring posts 4 on both sides of the rear of the steel caisson 6. While the steel caisson 6 moves toward the dock opening 73, the rear winch 1 is turned on to slowly and synchronously relax this part of the cable 5. In this way, the tension on the left and right sides of the steel caisson 6 is balanced, thereby avoiding tail swaying.

[0052] Combination Figure 8, the component numbers of the traction system are explained. In the present embodiment, four groups of traction systems are arranged in the dock 7, namely, traction system A, traction system B, traction system C and traction system D. It should be understood that in other embodiments, the traction systems may also be 6 groups, 8 groups or more. In the undocking direction of the steel caisson 6, the traction system A and traction system B are arranged at the front of the construction platform 62, and are respectively located on the left and right sides of the construction platform 62; the traction system C and traction system D are arranged at the rear of the construction platform 62, and are respectively located on the left and right sides of the construction platform 62. For the traction system A, the components in the system are respectively marked as: winch 1A, reversing wheel 2A, steering saddle 3A and cable 5A. The numbering of the components in the traction system B, traction system C and traction system D refers to the traction system A. In the undocking direction of the steel caisson 6, the mooring posts 4 located on the left dock wall 72 are marked in sequence from the dock opening 73 as follows: L1, L2, L3, L4, L5...; the mooring posts 4 located on the right dock wall 72 are marked in sequence from the dock opening 73 as follows: R1, R2, R3, R4, R5...

[0053] Now, in combination with the above hardware foundation and its numbering, the method is introduced. The method comprises the following steps:

[0054] Step 1: Connect the cable 5. Figure 8 As shown, at the front side of the steel caisson 6, the cable 5A is connected to the shackle 43 on the mooring post 4L1, and the cable 5B is connected to the shackle 43 on the mooring post 4R1; at the rear side of the steel caisson 6, the cable 5C is connected to the shackle 43 on the mooring post 4L6, and the cable 5D is connected to the shackle 43 on the mooring post 4R6. After all the groups of cables 5 are correctly connected, start each group of winches 1 to tighten the cables 5.

[0055] It should be explained that the cables 5C and 5D located at the rear side are more for balancing the left and right pulling forces of the steel caisson 6. As long as the second end 52 is connected to the mooring posts 4 behind the steering saddles 3C and 3D, and the left and right sides are symmetrically connected, the subsequent water injection and floating and the movement of the steel caisson 6 will not be affected. Therefore, in other embodiments, the mooring posts 4 connected to the cables 5C and 5D respectively should not be limited to L6 and R6. Corresponding to this step, the "front", "rear", "left" and "right" described in step 1 of claim 1 are relative to the undocking direction of the steel caisson 6.

[0056] Step 2: Fill with water to float. Fill water into the dock chamber 71 until the water level meets the conditions for undocking. During the water filling process, the steel caisson 6 will gradually float up. Therefore, it is necessary to start each group of winches 1 to slowly retract and release each group of cables 5 according to the height difference between the steel caisson 6 and the top of the dock wall 72, so that the cables 5 are in a slightly tightened state. At the same time, in order to ensure that the steel caisson 6 has a stable moving path and posture during the undocking process, the center line of the steel caisson 6 is fine-tuned to coincide with the center line of the dock chamber 71 as much as possible.

[0057] Combined with step 2, it can be explained why in step 1, it is not recommended to connect the cables 5C and 5D to the mooring posts 4 located in front of the steering saddles 3C and 3D, respectively. This is because: if the cables 5C and 5D are connected to the mooring posts 4 in front, the steel caisson 6 will move forward under the traction of each group of cables 5 during the process of water injection and buoyancy. If the water level in the dock 71 is not high, the steel caisson 6 is very likely to rub against the dock 71 at the bottom and cause structural damage.

[0058] Step 3: Towing out of the dock. When the water level in the dock chamber 71 rises to the set water level, start the winch 1A and winch 1B to synchronously tighten the cables 5A and 5B at the same rotation speed v1; at the same time, start the winch 1C and winch 1D to synchronously release the cables 5C and 5D at the same rotation speed v2 to control the steel caisson 6 to move to the dock opening 73 at a rate not exceeding 0.5 m / s. When the steel caisson 6 approaches the dock opening 73, the rope-retracting rate of the cables 5A and 5B and the rope-releasing rate of the cables 5C and 5D should be controlled to slowly decelerate the steel caisson 6. When the steel caisson 6 reaches the dock opening 73 and stops moving, tighten each group of cables 5 to stabilize the steel caisson 6.

[0059] Step 4: System transformation. When the steel caisson 6 is waiting for shipment at the dock 73, the construction personnel need to constantly start the winch 1 to fine-tune the posture of the steel caisson 6. However, at this time, the cables 5C and 5D are relatively long, and the angles formed with the left and right sides of the steel caisson 6 are relatively small, so that the cables 5C and 5D have relatively small vertical forces on the left and right sides of the steel caisson 6 when they are in tension, which brings certain operational difficulties to stabilizing the steel caisson 6. Therefore, in order to improve the stability of the steel caisson 6, the cables 5C and 5D are connected to the closer mooring posts 4.

[0060] like Fig. 9 As shown, two fiber ropes 8 are used to connect the left and right sides of the steel caisson 6 to the mooring posts 4L3 and 4L4 respectively and tighten them. Fig.10As shown, the second end 52 of the cable 5C is released from the mooring post 4L6 and replaced with the mooring post 4L4; similarly, the second end 52 of the cable 5D is released from the mooring post 4R6 and replaced with the mooring post 4R4. After the cables 5C and 5D are symmetrically connected and tensioned, the fiber rope 8 is released to complete the system transformation. It should be understood that the fiber rope 8 is the auxiliary rope described in the claims.

[0061] Similarly, when the connection point is changed, the cables 5C and 5D only need to be connected to the mooring posts 4 close to the steering saddles 3C and 3D and located behind the steering saddles 3C and 3D. Therefore, in other embodiments, the cables 5C and 5D can also be connected to the mooring posts 4L3 and 4L4 respectively.

[0062] Since the construction process of floating the steel caisson 6 by a tugboat is a common prior art and is not the focus of the present invention, it will not be described in detail herein. At this point, the steel caisson 6 has completed the undocking construction.

[0063] In summary, the method provided in the embodiment of the present invention uses the winch 1 of the steel caisson 6 to retract and release the cable 5 connected to the dock wall 72, and uses the principle of "action and reaction" between objects to safely and stably pull the steel caisson forward and out of the dock. This method uses a self-contained traction system to replace the tugboat, cleverly avoiding the problem of the steel caisson 6 squeezing the auxiliary tug sideways due to improper main tug operation, limited space, etc., which not only improves construction safety, but also reduces rental cost investment.

[0064] Secondly, at least four traction systems cooperate at the four corners of the steel caisson 6 to control the steel caisson 6 to move accurately in the four directions of front, back, left, and right, and to maintain dynamic balance. This method effectively solves the problem of the steel caisson 6 swinging left and right and colliding with the dock wall 72 due to the abandonment of lateral auxiliary towing in a narrow dock, and thus has high engineering applicability.

[0065] In addition, precisely because this method can utilize the winch 1 to precisely control the caisson, when encountering an emergency or approaching the destination, the steel caisson 6 has a higher braking performance, which is lacking in most towing and undocking methods.

[0066] Example 2

[0067] like Fig.11As shown, the embodiment of the present invention provides a method for undocking a large prefabricated structure based on a self-owned traction system, which is different from the method provided in Example 1 in that the hardware foundation applicable to the method is different. Specifically, the winch 1 is arranged on or near the center line of the steering saddle 3, and the retracting and releasing direction of the cable 5 is toward the steering saddle 3. Therefore, the traction system does not have the reversing wheel 2 and the matching second support and fixing frame 21 to reverse the cable 5 between the winch 1 and the steering saddle 3.

[0068] Except for the above differences, the rest of the method provided in this embodiment, including the specific undocking operation steps, is the same as the method provided in Embodiment 1.

[0069] The above description is only a preferred specific implementation mode of the present invention, and does not limit the patent scope of the present invention. Any technical equivalent changes made using the contents of the present invention specification shall fall within the protection scope of the present invention.

Claims

1. A method for undocking a large prefabricated structure based on a self-propelled traction system, characterized in that: Based on the following hardware foundation: The dock comprises a dock chamber, a dock wall and a dock opening; the dock wall extends on both sides of the dock chamber, and the dock opening is located at one end of the dock chamber close to the water area; the prefabricated structure is located in the dock chamber and undocking in the direction of the dock opening; A traction system, comprising a winch, a steering saddle, a plurality of mooring posts and a cable; the winch is installed on a construction platform on the top of the prefabricated structure to retract and release the cable; the steering saddle is installed on the edge of the top of the prefabricated structure; the steering saddle is constructed with a trumpet-shaped cable passage, the trumpet of which faces the outside of the prefabricated structure; the plurality of mooring posts are installed on the top of the dock walls on both sides of the dock and are arranged at intervals along the extension direction of the dock walls; the cable comprises a first end and a second end, the first end is fixed to the winch, the second end extends from the winch, passes through the cable passage of the steering saddle, and is finally connected to the mooring post; At least four groups of the traction systems are arranged in the dock, including traction system A, traction system B, traction system C and traction system D; in the undocking direction of the prefabricated structure, the traction system A and traction system B are arranged at the front of the construction platform, and are located on the left and right sides respectively; the traction system C and traction system D are arranged at the rear of the construction platform, and are located on the left and right sides respectively; The method comprises the following steps: Step 1: Connect the cable; in traction system A, connect the cable to the left mooring post closest to the dock; in traction system B, connect the cable to the right mooring post closest to the dock; in traction system C, connect the cable to a mooring post behind the left side of the steering saddle; in traction system D, connect the cable to a mooring post behind the right side of the steering saddle; Step 2: Filling water and floating up; filling water into the dock chamber until the water level meets the conditions for undocking; during the water filling process, each group of winches needs to be started to retract and release each group of cables according to the height difference between the prefabricated structure and the top of the dock wall; Step 3: Towing out of the dock; for traction system A and traction system B, the winches in the system are turned on to synchronously tighten the two cables in the front. At the same time, for traction system C and traction system D, the winches in the system are turned on to synchronously release the two cables in the rear to tow the prefabricated structure to the dock.

2. A method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: After step 3, there is step 4: system transformation; At least two auxiliary ropes are used to connect the left rear part and the right rear part of the prefabricated structure to the adjacent mooring posts respectively and tension them; then, in the traction system C, the second end of the rope is released from the original mooring post and connected to the adjacent mooring post at the left rear of the steering saddle; in the traction system D, the second end of the rope is released from the original mooring post and connected to the adjacent mooring post at the right rear of the steering saddle; further, the auxiliary rope is released.

3. A method for undocking a large prefabricated structure based on a self-propelled traction system according to any one of claims 1 or 2, characterized in that: In step 3, when the prefabricated structure approaches the dock, the rope-collecting rates of the winches in traction systems A and B and the rope-releasing rates of the winches in traction systems C and D are controlled to decelerate the prefabricated structure.

4. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: In step 3, the moving speed of the prefabricated structure is no more than 0.5 m / s.

5. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: In step 1, after all cables in the traction systems are correctly connected, start each group of winches to tighten the cables.

6. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: In step 2, when the prefabricated structure floats up, each group of winches is started to coordinate the length of each group of cables, so as to fine-tune the center line of the prefabricated structure to coincide with the center line of the dock chamber.

7. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: In step 2, the top of the prefabricated structure is higher than the top of the dock wall; during the water injection process, each group of winches is started to synchronously release each group of cables.

8. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: The direction of cable retraction and release of the winch is different from the extension direction of the cable channel in the steering saddle; the traction system also includes a reversing wheel; the reversing wheel is installed on the construction platform and is located near the intersection of the center lines of the winch and the steering saddle; the reversing wheel has rotational freedom in the horizontal plane; after the cable is led out from the winch, it is partially wrapped around the annular wheel and extends toward the steering saddle.

9. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: The steering saddle includes a bottom plate, side plates and a movable top plate; the bottom plate is trumpet-shaped and tilted or bent downward in the direction of the trumpet mouth; the two arc-shaped side plates are fixedly connected to the left and right sides of the bottom plate in the extension direction, and together with the top of the bottom plate, they construct a trumpet-shaped cable passage; the two side plates and the bottom of the bottom plate construct a support cavity, and the support cavity is filled with concrete; the side plate is fixedly connected to a stiffening frame on the side facing away from the cable passage; the movable top plate is detachably connected to the top of the stiffening frames on both sides to straddle the top of the cable passage.

10. The method for undocking a large prefabricated structure based on a self-propelled traction system according to claim 1, characterized in that: The traction system also includes a rope loop and a shackle; the rope loop is connected end to end through the shackle and then sleeved on the mooring post; the shackle can be opened and closed; the second end of the cable is provided with an annular rope loop; in steps 1 to 3, the cable is connected to the mooring post by passing the rope loop through the shackle.

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