Curved section large curvature crushed stone base bed and its laying method

Abstract

The present invention relates to the technical field of gravel base bed leveling for submarine tunnels, and in particular to a gravel base bed with large curvature in a curved section and a laying method thereof, comprising: a long ridge area near the head end of a pipe section to be installed and a short ridge area near the pipe section to be installed, the long ridge area comprising a plurality of parallel gravel ridges, each of which is parallel to the head end of the pipe section to be installed, the last gravel ridge and the tail end of the gravel base bed forming the short ridge area, the short ridge area being provided with short gravel ridges, the length of the short gravel ridge being less than that of the short gravel ridge, and the short gravel ridge being parallel to the head end of the pipe section to be installed, thereby ensuring that the elevation of the center of each ridge is the same, without elevation deviation and cumulative deviation, and enriching the gravel base bed ridge body design mode; the parallel and staggered arrangement of the gravel ridges ensures that the gravel base bed can fully support the curved pipe section without increasing the number of ship position arrangements, and can avoid the oblique movement of the stone-throwing pipe of the leveling ship, thereby reducing the laying difficulty.

Description

Technical Field

[0001] The present invention relates to the technical field of gravel base bed leveling for submarine tunnels, and in particular to a gravel base bed with large curvature in a curved section and a laying method thereof. Background Art

[0002] Undersea tunnels generally consist of straight and curved sections. The gravel bed for the straight sections is arranged along the tunnel axis. For curved sections with a smaller radius of curvature, the gravel bed can be laid using a straight-line arrangement. However, for curved sections with a larger radius of curvature, the conventional straight-line arrangement can no longer guarantee full support for the gravel bed.

[0003] If the large-curvature gravel base bed is laid out in a way that each ridge passes through the center of the circle, theoretically, since the arc length of each point on the ridge from the head end of the pipe section is different, the elevation of each ridge will be different, generally high on the outside and low on the inside, and the farther away from the head end of the pipe section, the greater the cumulative deviation, and the accumulated deviation to the last ridge will exceed the allowable range of construction error.

[0004] Therefore, it is necessary to design a gravel base bed suitable for curved sections with large curvature, so as to smoothly complete the leveling construction of the gravel base bed in the curved section and meet the installation conditions of the curved pipe section. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a curved section large-curvature gravel base bed and a laying method thereof, which can fully support the curved section pipe segment and is easy to construct.

[0006] The present invention provides a gravel base bed with a large curvature in a curved section, characterized in that the gravel base bed includes a long ridge area close to the head end of the pipe section to be installed and a short ridge area close to the pipe section to be installed, the long ridge area includes multiple parallel gravel ridges, and each of the gravel ridges is parallel to the head end of the pipe section to be installed, the last gravel ridge and the tail end of the gravel base bed form the short ridge area, short gravel ridges are arranged in the short ridge area, the length of the short gravel ridge is less than the length of the gravel ridge, and the short gravel ridge is parallel to the head end of the pipe section to be installed.

[0007] The curved section with large curvature gravel base bed of this technical solution can meet the installation and construction requirements of the curved section with large curvature immersed tube segments, and can fully support the curved section pipe segments. Each gravel ridge is set in parallel with the head end of the pipe segment, which can ensure that the elevation of the center of each ridge is the same, and there is no elevation deviation or cumulative deviation, which enriches the design method of the gravel base bed ridge body.

[0008] In some embodiments of the present application, each of the gravel ridges is of different lengths and is staggered, ensuring that the entire gravel base bed can fully support the curved pipe section without increasing the number of ship position arrangements, and avoiding the diagonal movement of the leveling ship's stone-throwing pipe, thereby reducing the difficulty of laying construction.

[0009] In some embodiments of the present application, the short ridge area is a triangular area, and the length of the short gravel ridge gradually shortens in the direction approaching the tail end of the immersed tube.

[0010] In some embodiments of the present application, the maximum distance between the position of the last short gravel ridge and the tail end of the pipe segment is no more than 2.2 m, to prevent the tail end of the pipe segment from being suspended a large distance, which would affect the later installation and construction of the pipe segment.

[0011] In some embodiments of the present application, a transition section is connected between two adjacent gravel ridges, and a transition section is also provided between two adjacent short gravel ridges, and the transition section is perpendicular to the gravel ridge.

[0012] The above-mentioned method for laying the gravel base bed specifically includes the following steps:

[0013] S1. Preparation before construction:

[0014] The leveling ship enters the construction site and takes position; the supply ship enters the construction site and takes position;

[0015] S2. Laying of gravel ridges in long ridge areas:

[0016] The gravel base bed is arranged in ship positions, with the first ship position being set at a position near the head end of the immersed tube in the long ridge area. According to the staggered and parallel distribution characteristics of the gravel ridges, the leveling ship is moved to the construction position of the first ship position, the moon pool edge of the leveling ship is adjusted to be parallel to the gravel ridge, the walking trolley and the walking cart of the leveling ship are moved, the riprap pipe on the leveling ship is moved to the starting position of the first gravel ridge in the first ship position, the riprap pipe is lowered to the construction height, the feeding ship transports the stone into the riprap pipe, and according to the coordinates and elevation parameters of each gravel ridge, the walking trolley and the walking cart are moved to lay the gravel ridges row by row until the gravel ridges in the first ship position are laid.

[0017] S3. Laying of gravel ridges for the remaining ship positions:

[0018] After the construction of the gravel ridge at the first ship position is completed, the riprap pipe is lifted a certain distance, the leveling ship is moved to the position of the second ship position, the traveling trolley and the traveling trolley are moved to the starting position of the gravel ridge at the second ship position, the riprap pipe is lowered to the construction height, and the gravel ridge is laid row by row until the gravel ridge at the second ship position is completed; the above operation is repeated until the gravel ridge in the long ridge area of ​​the last ship position is completed;

[0019] S4. Laying of short gravel ridges in short ridge areas:

[0020] After the gravel ridge of the last ridge of the last ship position is laid, the walking trolley is moved to the starting position of the first short gravel ridge. After the walking cart is moved to complete the laying of the first short gravel ridge, the scraper height is maintained unchanged, and the walking cart returns to the starting position of the first short gravel ridge. The walking trolley is moved to the starting position of the second short gravel ridge, and the walking cart is moved to complete the laying of the second short gravel ridge. Repeat the above operation until the laying of the last short gravel ridge is completed.

[0021] In some embodiments of the present application, in steps S2 and S3, when the previous gravel ridge is laid, the walking cart and the walking trolley move to the end position of the current gravel ridge, the walking cart does not move, and the walking trolley moves the distance of the ridge width. At this time, the transition section between the two gravel ridges is laid, the riprap pipe reaches the starting position of the next gravel ridge, and the walking cart is moved to lay the next gravel ridge; since the gravel ridges of the curved section pipe section are staggered and parallel, the edge of each ship position moon pool must be parallel to the gravel ridge, so when laying the transition section at a turn, only the walking trolley needs to be moved.

[0022] In some embodiments of the present application, in step S4, after the short gravel ridge is laid according to the designed length, the short gravel ridge near the tail end of the pipe segment is an intrusion ridge body, and the intrusion ridge body intrudes into the pipe segment docking position. In order to prevent the gravel from being clamped in the joint cavity during installation, part of the elevation of the intrusion ridge body is scraped off so that the elevation of the intrusion ridge body is lower than the original elevation by more than 50 cm, thereby providing safety conditions for the subsequent installation of the immersed tube.

[0023] In some embodiments of the present application, in step S4, since the length of the short gravel ridge gradually shortens in the direction approaching the tail end of the immersed tube, after the current short gravel ridge is laid, the scraper maintains the original height and returns to the starting position of the current short gravel ridge, and then moves the walking trolley diagonally to the starting position of the next short gravel ridge, and the walking trolley follows.

[0024] Based on the above technical solution, the gravel base bed of the present invention can meet the installation and construction requirements of the large-curvature immersed pipe segment in the curved section, can fully support the curved section pipe segment, and each gravel ridge is arranged in parallel with the head end of the pipe segment, which can ensure that the elevation of the center of each ridge is the same, and there is no elevation deviation or cumulative deviation, which enriches the design method of the gravel base bed ridge body;

[0025] The parallel staggered arrangement of gravel ridges ensures that the gravel base bed can fully support the curved pipe section without increasing the number of ship layouts. It also avoids the diagonal movement of the stone pipe caused by the leveling ship and reduces the difficulty of laying. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 Schematic diagram of the structure of the gravel base bed in an embodiment of the present invention;

[0028] Figure 2 This is a schematic structural diagram of the short ridge area in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of ship positioning for a gravel bed according to an embodiment of the present invention;

[0030] Figure 4 This is a position relationship diagram of the leveling ship moving to the first ship position in an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of the starting position of laying gravel ridges adjacent to ship positions in an embodiment of the present invention;

[0032] Figure 6 Schematic diagram of the structure of the gravel base bed at the joint of two immersed tubes in an embodiment of the present invention.

[0033] In the figure,

[0034] 10. Long ridge area; 11. Gravel ridge; 12. Transition section; 20. Short ridge area; 21. Short gravel ridge; 22. Intrusion into the ridge body; 30. Pipe section to be installed. DETAILED DESCRIPTION

[0035] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "transverse", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying 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 orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0037] The terms "first," "second," and "third" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first," "second," or "third" may explicitly or implicitly include one or more of such features.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] The gravel base bed with large curvature of the curved section in this embodiment is suitable for the installation of the pipe segment 30 to be installed with a curve radius of 1050m. If the traditional method of "replacing the curve with a straight line" is used to install the immersed pipe, the gravel base bed is laid out in a way that each gravel ridge passes through the center of the circle. In theory, the elevation of each ridge is different (high outside and low inside). The reason is that the arc length from each point on the ridge to the head end of the pipe segment is different, and the farther away from the head end of the pipe segment, the greater the cumulative deviation. When the last ridge reaches (l 外 -l 内 )*i 坡度 % = (150.3539m-145.6461m)*0.65% = 0.0301m, which exceeds the maximum error range allowed by the project.

[0040] like Figure 1 As shown, in this embodiment, the curved section gravel base bed with large curvature includes a long ridge area 10 near the head end of the pipe section 30 to be installed and a short ridge area 20 near the pipe section 30 to be installed. The short gravel ridge 20 is Figure 1 The remaining part of the triangular area surrounded by the dotted line is the long ridge area 10; the long ridge area 10 includes a plurality of parallel gravel ridges 11, and each gravel ridge 11 is parallel to the head end of the pipe section 30 to be installed, and the last gravel ridge 11 and the tail end of the gravel bed form the short ridge area 20. Figure 1 In the triangular area shown, a short gravel ridge 21 is provided in the short ridge area 20. The length of the short gravel ridge 21 is less than the length of the gravel ridge 11 in the long ridge area 10, and the short gravel ridge 21 is also parallel to the head end of the pipe segment 30 to be installed.

[0041] The curved section with large curvature gravel base bed of this technical solution can meet the installation and construction requirements of the curved section with large curvature immersed pipe segments, and can fully support the curved section pipe segments. Each gravel ridge is set in parallel with the head end of the pipe segment, which can ensure that the elevation of the center of each ridge is the same. A short ridge area in a triangular area is formed at the tail end of the pipe segment, and short gravel ridges are arranged in the short ridge area 20 to eliminate the elevation difference between the inside and the outside. There is no elevation deviation and cumulative deviation in the gravel base bed, which enriches the design method of the gravel base bed ridge body.

[0042] like Figure 1 As shown, the gravel base bed of this embodiment has a total of 52 ridges, including 50 gravel ridges 11 and two short gravel ridges 21. The length of each gravel ridge 11 is different and they are staggered. The length of the first 50 gravel ridges ranges from 40 to 41 meters, ensuring that the entire gravel base bed can fully support the curved pipe section without increasing the number of ship positioning times. It can also avoid the oblique movement of the stone pipe when the leveling ship is ripped, reducing the difficulty of laying construction.

[0043] like Figure 1 As shown, the short ridge area 20 is a triangular area. In this embodiment, the short ridge area 20 has two short gravel ridges 21, and the length of the short gravel ridge 21 gradually shortens as it approaches the tail end of the pipe section 30 to be installed. The length of the first short gravel ridge is 33.8m, and the length of the second short gravel ridge is 12.9m. Figure 2 As shown, the maximum suspension distance D between the last short gravel ridge 21 and the tail end of the pipe segment does not exceed 2.2 m, so as to prevent the tail end of the pipe segment from being suspended too far and affecting the later installation and construction of the pipe segment.

[0044] A transition section 12 is connected between two adjacent gravel ridges 11. The end point of the previous gravel ridge 11 and the starting point of the next gravel ridge 11 are connected by the transition section 12. A transition section is also provided between the starting points of two adjacent short gravel ridges 21. The transition section 12 is perpendicular to the gravel ridge 11. The transition sections 12 are alternately arranged at both ends of the ridge body of the gravel base bed.

[0045] Figure 1 The method for laying the gravel base bed shown specifically includes the following steps:

[0046] S1. Preparation before construction:

[0047] The leveling vessel enters the construction site and uses the anchor cable system to position the leveling vessel at the laying operation location, with the plane positioning accuracy controlled within ±100mm. The supply vessel enters the construction site and is stationed at a preset distance from the leveling vessel. In this embodiment, the supply vessel is stationed outside the leveling vessel, maintaining a distance of more than 5m from the leveling vessel to prevent the leveling vessel or the supply vessel from dragging anchor and causing a ship collision.

[0048] S2. Laying of gravel ridge at the first ship position in the long ridge area:

[0049] In accordance with the principle of including as many gravel ridges as possible in each position, Figure 1 The gravel bed shown is provided with six berths. The first to fifth berths are 9 ridges, the sixth berth is 7 ridges, and a total of 52 ridges. The first berth is located in the long ridge area 10 near the head end of the immersed tube. Figure 3 As shown; According to the staggered and parallel distribution characteristics of the gravel ridges, the leveling ship moves to the construction position of the first ship position, as shown Figure 4 shown.

[0050] Adjust the moonpool edge of the leveling ship to be parallel to the gravel ridge. Move the leveling ship's trolley and trolley, move the riprap pipe on the leveling ship to the starting position of the first gravel ridge at the first ship's position, lower the riprap pipe to the construction height, and the feed ship delivers stone into the riprap pipe. According to the coordinates and elevation parameters of the first gravel ridge, move the trolley to complete the laying of the first gravel ridge. At this time, the trolley and trolley are located at the end position of the first gravel ridge. Keeping the trolley stationary, the trolley moves vertically a distance of one ridge width to complete the laying of the transition section 12 between the first and second gravel ridges. At this time, the trolley reaches the starting position of the second gravel ridge. According to the coordinates and elevation parameters of the second gravel ridge, move the trolley to complete the laying of the second gravel ridge. Repeat the above steps until all nine gravel ridges at the first ship's position have been laid.

[0051] S3. Laying of gravel ridges for the remaining ship positions:

[0052] Since the gravel ridges 11 of the curved pipe section are arranged in parallel and staggered, the side of the moon pool of each ship position must be parallel to the gravel ridge 11. During construction, the ridges should be leveled according to the designed laying order. When changing ridges, they should be turned vertically. Just like the straight section, only the walking trolley needs to be moved. When defining the starting point of each ship position, it should be changed according to the design drawings. It cannot start only from the stern. The bow and stern of each ship position need to be alternately used as the starting point for laying the gravel ridge 11. Figure 5 As shown, it is avoided that when laying and changing ridges, the traveling cart and the traveling trolley move at the same time and the riprap pipe moves diagonally.

[0053] If the ridge is laid in straight sections, meaning the first ridge at each position always begins at the stern, then when turning in the opposite direction of the designed route, not only the trolley moves, but the large vehicle also has to follow. This makes it difficult to control the speed of the large vehicle and trolley, and controlling diagonal movement is also challenging. Therefore, when leveling curved sections, the ridge must be laid according to the movement direction specified in the design.

[0054] After the construction of the gravel ridge 11 of the first ship position is completed, the riprap pipe is lifted a certain distance to ensure the safe movement of the leveling ship and prevent the leveling ship from colliding with seabed obstacles during movement. The walking cart and the walking trolley are moved to the middle position to keep the center of gravity of the leveling ship in the middle position, and then the leveling ship is moved to the position of the second ship position. The walking cart and the walking trolley are moved to the starting position of the first gravel ridge 11 of the second ship position, the riprap pipe is lowered to the construction height, and the gravel ridges are laid row by row until the gravel ridges of the second ship position are completed.

[0055] Repeat the above operation until the laying of the fourth gravel ridge 11 at the sixth ship position is completed; the laying of the gravel ridge 11 in the long ridge area 10 is completed.

[0056] In steps S2 and S3, when the previous gravel ridge is laid, the walking cart and the walking trolley move to the end position of the current gravel ridge, the walking cart does not move, and the walking trolley moves the distance of the ridge width to complete the laying of the transition section between the two gravel ridges. The riprap pipe reaches the starting position of the next gravel ridge, and the walking cart is moved to lay the next gravel ridge; since the gravel ridges of the curved section pipe section are staggered and parallel, the edge of each ship position moon pool must be parallel to the gravel ridge, so when laying the transition section at a turn, only the walking trolley needs to be moved.

[0057] S4. Laying of short gravel ridges in short ridge areas:

[0058] After the fourth gravel ridge 11 at the sixth position is laid, a triangular area will be formed at the tail end of the pipe section. At this time, a short ridge will be arranged in the triangular area to eliminate the elevation difference between the inside and outside. Move the trolley to the starting point of the first short gravel ridge 21. This process involves laying the transition section between the end point of the last gravel ridge 11 and the starting point of the first short gravel ridge 21. Then move the trolley 33.8m to complete the laying of the first short gravel ridge 21. Then, maintain the scraper height unchanged, move the trolley back to the starting point of the first short gravel ridge, move the trolley to the starting point of the second short gravel ridge, and at the same time, lay the transition section between the starting point of the first short gravel ridge 21 and the starting point of the second short gravel ridge 21. Then move the trolley 12.9m to complete the laying of the second short gravel ridge 21. Since the length of the short gravel ridge gradually shortens toward the tail end of the immersed tube, after the first short gravel ridge is laid, the scraper maintains its original height and returns to the starting position of the first short gravel ridge, and then moves the trolley diagonally to the starting position of the second short gravel ridge, with the trolley following.

[0059] In step S4, after the short gravel ridge 21 is laid according to the designed length, the short gravel ridge near the end of the pipe segment is the intrusion ridge body 22. Figure 6As shown, the intruding ridge body 22 intrudes into the joint position of the pipe section. In order to prevent the gravel from being clamped in the joint cavity during installation, part of the elevation of the intruding ridge body 22 is scraped off, so that the elevation of the intruding ridge body 22 of the first short gravel ridge is more than 50 cm lower than the elevation of the first short gravel ridge, and the elevation of the intruding ridge body 22 of the second short gravel ridge is more than 50 cm lower than the elevation of the second short gravel ridge, providing safety conditions for the subsequent installation of the immersed tube.

[0060] A leveling head is mounted at the bottom of the riprap tube. This head further comprises a scraper and multiple hydraulic cylinders. Four hydraulic cylinders are evenly spaced around the base of the riprap tube. Each cylinder is equipped with a length sensor that communicates with the leveling vessel's measurement and control system. This transmits the cylinder's extension length in real time to the system, enabling real-time monitoring of the scraper's elevation. This allows for vertical movement and monitoring of the scraper's elevation. Furthermore, a sonar system is mounted on the outer frame of the leveling head to monitor the quality of the gravel bed.

[0061] During the bed laying and leveling operation, the moving speed of the trolley and the traveling carriage shall not exceed 2m / min. The measurement and control system of the leveling vessel will display the position and speed of the trolley and the traveling carriage in real time. This helps to ensure the stability of the leveling vessel and, in turn, the smooth progress of the gravel bed laying and leveling operation.

[0062] The gravel base bed of the present invention can meet the installation and construction requirements of the large-curvature immersed pipe segments in curved sections, and can fully support the curved section pipe segments. Each gravel ridge is arranged in parallel with the head end of the pipe segment, which can ensure that the elevation of the center of each ridge is the same, and there is no elevation deviation or cumulative deviation, which enriches the design method of the gravel base bed ridge body; the gravel ridges are arranged in parallel and staggered manner, which ensures that the gravel base bed can fully support the curved pipe segments without increasing the number of ship position arrangements, and can avoid the oblique movement of the stone pipe riprap from the leveling ship, thereby reducing the difficulty of laying.

[0063] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to preferred embodiments, persons skilled in the art should understand that the specific implementation methods of the present invention may still be modified or some technical features may be replaced by equivalents without departing from the spirit of the technical solutions of the present invention, and all of these should fall within the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A method for laying a curved section gravel base bed with large curvature, characterized by: The gravel base bed includes a long ridge area near the head end of the pipe section to be installed and a short ridge area near the pipe section to be installed. The long ridge area includes multiple parallel gravel ridges, and each of the gravel ridges is parallel to the head end of the pipe section to be installed. The last gravel ridge and the tail end of the gravel base bed form the short ridge area. Short gravel ridges are arranged in the short ridge area. The length of the short gravel ridge is less than that of the gravel ridge, and the short gravel ridge is parallel to the head end of the pipe section to be installed. The method for laying the gravel base bed comprises the following steps: S1. Preparation before construction: The leveling ship enters the construction site and takes position; the supply ship enters the construction site and takes position; S2. Laying of gravel ridge at the first ship position in the long ridge area: The gravel base bed is laid out in ship positions, with the first ship position being set at a position near the head end of the immersed tube in the long ridge area, the leveling ship is moved to the construction position of the first ship position, the moon pool edge of the leveling ship is adjusted to be parallel to the gravel ridge, the walking trolley and the walking cart of the leveling ship are moved, the riprap pipe on the leveling ship is moved to the starting position of the first gravel ridge in the first ship position, the riprap pipe is lowered to the construction height, the feeding ship transports the stone into the riprap pipe, and according to the coordinates and elevation parameters of each gravel ridge, the walking trolley and the walking cart are moved to lay the gravel ridges row by row until the gravel ridges in the first ship position are laid. S3. Laying of gravel ridges for the remaining ship positions: After the construction of the gravel ridge at the first position is completed, the riprap pipe is lifted a certain distance, the leveling ship is moved to the position of the second position, the traveling trolley and the traveling carriage are moved to the starting position of the gravel ridge at the second position, the riprap pipe is lowered to the construction height, and the gravel ridge is laid row by row until the gravel ridge at the second position is completed; the above operation is repeated until the gravel ridge in the long ridge area of ​​the last position is completed; S4. Laying of short gravel ridges in short ridge areas: After the gravel ridge of the last ridge of the last ship position is laid, the walking trolley is moved to the starting position of the first short gravel ridge. After the walking cart is moved to complete the laying of the first short gravel ridge, the scraper height is maintained unchanged, and the walking cart returns to the starting position of the first short gravel ridge. The walking trolley is moved to the starting position of the second short gravel ridge, and the walking cart is moved to complete the laying of the second short gravel ridge. Repeat the above operation until the laying of the last short gravel ridge is completed.

2. The method for laying a curved section large curvature gravel base bed according to claim 1, characterized in that: The length of each gravel ridge is different and the ridges are staggered.

3. The method for laying a curved section large curvature gravel base bed according to claim 2, characterized in that: The short ridge area is a triangular area, and the length of the short gravel ridge gradually shortens in the direction close to the tail end of the immersed tube.

4. The method for laying a curved section large curvature gravel base bed according to claim 3, characterized in that: The maximum distance between the position of the last short gravel ridge and the tail end of the pipe section is no more than 2.2m.

5. The method for laying a curved section large curvature gravel base bed according to claim 4, characterized in that: A transition section is connected between two adjacent gravel ridges, and the transition section is perpendicular to the gravel ridges.

6. The method for laying a curved segment high curvature gravel base bed according to claim 1, characterized in that: In steps S2 and S3, when the previous gravel ridge is laid, the walking cart and the walking trolley move to the end position of the current gravel ridge, the walking cart does not move, and the walking trolley moves the distance of the ridge width. At this time, the transition section between the two gravel ridges is laid, the riprap pipe reaches the starting position of the next gravel ridge, and the walking cart is moved to lay the next gravel ridge; since the gravel ridges of the curved section pipe section are staggered and parallel, the edge of each ship position moon pool must be parallel to the gravel ridge, so when laying the transition section at a turn, only the walking trolley needs to be moved.

7. The method for laying a curved segment high curvature gravel base bed according to claim 6, characterized in that: In step S4, after the short gravel ridge is laid according to the designed length, the short gravel ridge near the tail end of the pipe segment is the intrusion ridge body. The intrusion ridge body intrudes into the pipe segment docking position, and part of the elevation of the intrusion ridge body needs to be scraped off so that the elevation of the intrusion ridge body is more than 50 cm lower than the original elevation.

8. The method for laying a curved section large curvature gravel base bed according to claim 7, characterized in that: In step S4, after the current short gravel ridge is laid, the scraper maintains the original height and returns to the starting position of the current short gravel ridge, and then moves the walking trolley diagonally to the starting position of the next short gravel ridge, and the walking trolley follows.

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