A modular underwater maintenance staircase and its assembly method

Abstract

This invention relates to the field of staircase technology, specifically a modular underwater maintenance staircase and its assembly method. The invention comprises a maintenance staircase consisting of at least two stair sections connected end-to-end. Both ends of the maintenance staircase are hinged to a structural wall via hinge seats. At adjacent ends of adjacent stair sections, a first hinge sleeve and a second hinge sleeve, coaxially penetrated by pins, are pre-embedded and fixed to form a hinge joint for the hinged floating of adjacent stair sections. Damping shafts are pre-embedded and fixed to the sidewalls at adjacent ends of adjacent stair sections. Each damping shaft has a first hook and a second hook that rotatably engage with each other to form a Jennings hook. The Jennings hooks are arranged in two sets symmetrically on both sides of the adjacent ends of adjacent stair sections. This invention improves construction efficiency, enhances adaptability to aquatic environments, improves structural safety, and reduces negative environmental impacts during construction and assembly.

Description

Technical Field

[0001] This invention relates to the field of staircase technology, specifically a modular underwater maintenance staircase and its assembly method. Background Technology

[0002] For water-related environments such as rainwater storage tanks, reservoirs, and dams, which often involve the maintenance of internal areas, as described in the text of Chinese Patent Publication No. CN208415476U entitled "Deep Foundation Pit Rainwater Storage Tank with Maintenance Platform", steel ladders are installed on the inner wall of the tank to allow people to climb to various heights inside the tank for maintenance work.

[0003] Currently, the staircases used for maintenance in the aforementioned water-related environments are mainly of two types: steel structure staircases and concrete staircases. Steel structure staircases are mostly of the type described in the cited patent, which is a fixed, integrated structure formed by on-site welding. Concrete staircases are also mostly of the type of fixed, integrated structure, primarily using the casting mold described in the text of Chinese Patent Publication No. CN216860108U entitled "A Precast Casting Mold for Dam Slope Gallery," and are constructed using on-site casting.

[0004] Since the structural walls constituting the inner walls of rainwater storage tanks, reservoirs, and dams are mostly inclined, staircases are often installed with their bottoms attached to these inclined structural walls to achieve better stability. However, the aforementioned integrated fixed staircase structures still have the following problems when applied in water-related environments: First, both types of staircase structures rely on on-site welding or casting, which involves cumbersome construction and is greatly affected by the water environment, resulting in long construction times and low construction efficiency. Second, integrated fixed staircases are difficult to adapt to the slight deformations of the reservoir dam body caused by water erosion, exhibiting poor adaptability. Third, the rigid welded joints of integrated fixed staircases lack effective buffering and self-adaptive mechanisms, making them susceptible to structural damage due to water impact or dam deformation, thus limiting safety. Fourth, welding processes generate noise, harmful gases, and light pollution, while on-site concrete casting requires formwork and other procedures, consuming manpower and resources. Therefore, these issues urgently need to be addressed. Summary of the Invention

[0005] To avoid and overcome the technical problems existing in the prior art, the present invention provides a modular underwater maintenance staircase and assembly method, which can improve construction efficiency, enhance adaptability to water-related environments, improve structural safety, and reduce the negative environmental impact during construction and assembly.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A modular underwater maintenance staircase includes a maintenance staircase consisting of at least two stair sections connected end to end. The two ends of the maintenance staircase are respectively hinged to the structural wall via hinge seats. The adjacent ends of adjacent stair sections are respectively pre-embedded with a first hinge sleeve and a second hinge sleeve that can be coaxially passed through by a pin, so as to jointly form a hinge joint for the hinged floating of adjacent stair sections. The side walls of the adjacent ends of adjacent stair sections are respectively pre-embedded with damping shafts. Each of the two damping shafts has a first hook and a second hook that cooperate with each other to form a James hook. The James hook is set as two sets symmetrically arranged on both sides of the adjacent ends of adjacent stair sections. The hinge axis of the hinge seat, the hinge axis of the hinge joint, the axis of the damping shaft, and the central axis of the James hook are all parallel to the length direction of the horizontal step surface of the stair section.

[0008] As a further aspect of the present invention, the installation height of the James hook is lower than the installation height of the hinge joint.

[0009] As a further embodiment of the present invention: the first hinge sleeve is fixed on the vertical stair wall at the end of the stair section. The first hinge sleeve includes a first fixing plate fixed to the vertical stair wall and a first sleeve fixed on the first fixing plate for a pin to pass through coaxially. The first fixing plate is bolted to the vertical stair wall, and a first pre-embedded tenon is also fixed on the first fixing plate and embedded in the vertical stair wall.

[0010] As a further embodiment of the present invention: the second hinge sleeve is fixed on the horizontal step surface at the first end of the stair section. The second hinge sleeve includes a second fixing plate fixed to the horizontal step surface and a second sleeve fixed on the second fixing plate for the pin to pass through coaxially. The second fixing plate is bolted to the vertical step wall, and a second pre-embedded tenon is also fixed on the second fixing plate and embedded in the horizontal step surface.

[0011] As a further aspect of the present invention: a set of hinge sleeve units consisting of two first hinge sleeves and a second hinge sleeve located between them, wherein at least two sets of hinge sleeve units are arranged sequentially along the hinge axis direction of the hinge joint.

[0012] As a further embodiment of the present invention: the pin includes a rod body that passes through the first hinge sleeve and the second hinge sleeve and a nut that is threaded onto the tail of the rod body. The head of the rod body has a protrusion, and the protrusion at the head of the rod body and the nut at the tail restrict the pin from separating from the first hinge sleeve and the second hinge sleeve.

[0013] As a further embodiment of the present invention: the vertical step walls at the near ends of adjacent stair sections are arranged close together, and there is a floating interval between the vertical step walls of the two for the hinged floating of adjacent stair sections, and a buffer component is provided at the floating interval.

[0014] As a further embodiment of the present invention: the buffer assembly includes a first buffer and a second buffer, which are respectively fixed on the vertical stair walls at the near ends of adjacent stair sections. The first buffer and the second buffer are both located on the same circumference with the hinge axis of the hinge section as the center.

[0015] As a further embodiment of the present invention: the first buffer and the second buffer are both made of rubber, silicone or buffer springs, and both are fixed to the vertical step wall by anchors.

[0016] Assembly method, applied to the aforementioned modular underwater maintenance staircase, includes the following steps:

[0017] S1. Hinge and fix the first stair section to the upper part of the structural wall;

[0018] S2. Hoist the first end of the adjacent lower stair section to the tail end of the adjacent upper stair section, and snap-fit ​​the first hook and the second hook that form the James hook at the near ends of the two.

[0019] S3. Using the snap-fit ​​assembled James hook as the rotating floating node, adjust the lower stair section and align the axes of the first hinge sleeve and the second hinge sleeve. Then, coaxially pass the rod of the pin through the first hinge sleeve and the second hinge sleeve, and screw a nut into the tail of the rod.

[0020] S4. Install the adjacent lower stair sections in sequence until the last stair section and its adjacent upper stair section are completed. At this point, the lower wall of the maintenance staircase composed of all stair sections is arranged in close contact with the structural wall. Finally, the tail end of the last stair section is hinged and installed on the lower part of the structural wall.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The maintenance staircase of this application is constructed by combining multiple stair sections. The stair sections are connected by hinged joints and James hooks, which makes the construction process convenient and efficient and reduces the negative impact on the environment during construction and assembly. Furthermore, under the combined effect of the two connections of hinged joints and James hooks, the slope can be adaptively adjusted when subjected to continuous impact loads caused by water fluctuations. The buffer device inside the James hook also has a certain buffering effect, converting the impact force into controllable deformation. This allows the system to continue to operate well in different situations in water, enhancing its adaptability to water-related environments and its safety of use.

[0023] Furthermore, when the inclined wall of the structural wall undergoes slight hollow changes due to the weak scouring effect of the water flow, the maintenance personnel can step on the hollow area of ​​the structural wall and the maintenance staircase will adjust to a certain adaptive angle under the weight of their feet, so that the bottom of the maintenance staircase is as close to the structural wall as possible. When the hollow area of ​​the structural wall is larger, the maximum adaptive adjustment angle of the maintenance staircase can be limited by the James hook when the maintenance personnel step on it. While the maintenance staircase is as close to the structural wall as possible, it avoids large deformation of the maintenance staircase and excessive swaying when walking.

[0024] 2. The installation height of the James hook is lower than that of the hinge joint. This results in the overall structural stiffness curve of the maintenance staircase being a double-folded line due to the superposition of the two connection effects of the hinge joint and the James hook. Under low load, the hinge joint dominates, while under high load, the James hook intervenes, which can reduce the increase in stiffness and avoid brittle failure.

[0025] 3. The layout, where the first hinge sleeve is fixed to the vertical step wall at the end of the stair section, and the second hinge sleeve is fixed to the horizontal step surface at the beginning of the stair section, ensures that both the first and second hinge sleeves are exposed within the construction worker's field of vision, facilitating accurate alignment during construction. Furthermore, both the first and second hinge sleeves are fixed to the stair section using fixing plates. In addition to bolt anchoring, pre-embedded tenons and mortises within the stair section significantly enhance the connection stability between the hinge sleeves and the stair section.

[0026] 4. Based on the fact that the first and second hinge sleeves can be easily and accurately aligned coaxially during assembly, a hinge sleeve unit is formed by two first hinge sleeves and a second hinge sleeve located between them. The hinge sleeve unit is set to be arranged in at least two groups along the hinge axis of the hinge joint, which effectively enhances the connection stability between adjacent stair sections.

[0027] 5. The vertical step walls at the near ends of adjacent stair sections are arranged close together, and there is a floating gap between the vertical step walls for the hinged floating of adjacent stair sections, with a buffer component installed at the floating gap. The buffer component prevents direct impact damage to the stair surface at the connection point when the angle changes, effectively extending the service life of the staircase, reducing the consumption of manpower and material resources for later maintenance, and achieving energy conservation.

[0028] 6. The buffer assembly includes a first buffer and a second buffer, which are respectively fixed to the vertical stair walls at the near ends of adjacent stair sections. This means that when the adaptive adjustment angle of the staircase is being inspected, the collision between the first and second buffers is buffered, and the buffer structure does not need to act directly on the stair section, further reducing damage to the stair section.

[0029] 7. The maintenance staircase, assembled from multiple hinged stair sections, allows for better fit of the bottom of the staircase against the inclined surface of the structural wall. It also enables underwater assembly operations, which are difficult to achieve with welding and monolithic casting, even in wet environments. During assembly, the stair sections are assembled sequentially according to the site conditions, and the connection is completed by impact using a James hook. This rapid positioning and snap-fitting eliminates the need for complex equipment, shortening the operation time. Subsequently, using the James hook as a rotating floating node, the stair sections are adjusted to quickly and accurately align the first and second hinge sleeves coaxially, and finally, a pin is inserted to ensure coaxial penetration, further guaranteeing the efficiency of the assembly operation. Compared to traditional welding methods, this avoids the adverse environmental impact of some welding-related harmful gases. Compared to monolithic casting, it eliminates the need for cumbersome on-site assembly of casting molds and post-casting curing procedures, reducing on-site operations, noise, and harmful gas generation, thus minimizing the impact on the surrounding environment. Attached Figure Description

[0030] Figure 1 This is a partial front view structural diagram of the present invention.

[0031] Figure 2 This is a partial top view of the exploded structure of the present invention.

[0032] Figure 3 This is a partial first side view of the structure of the present invention.

[0033] Figure 4 This is a partial second side view of the structure of the present invention.

[0034] Figure 5 This is a partial structural diagram of the present invention and the distribution of structural walls.

[0035] In the diagram: 10, stair section; 20, hinge section; 21, first hinge sleeve; 211, first fixing plate; 212, first sleeve; 213, first embedded tenon and mortise; 22, second hinge sleeve; 221, second fixing plate; 222, second sleeve; 223, second embedded tenon and mortise; 23, pin; 231, rod body; 232, nut; 30, James hook; 31, first hook part; 32, second hook part; 40, buffer assembly; 50, structural wall. Detailed Implementation

[0036] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] For ease of understanding, the specific structure and operation of the present invention will be further described below with reference to the accompanying drawings:

[0038] The specific structure of this invention is as follows: Figure 1-5 As shown, its main structure includes a maintenance staircase consisting of at least two stair sections 10 connected end to end. The two ends of the maintenance staircase are hinged to the structural wall 50 (such as the inclined dam wall of a dam or the inclined pool wall of a rainwater storage tank, etc.) via hinge seats. Furthermore, adjacent stair sections 10 have pre-embedded and fixed first hinge sleeves 21 and second hinge sleeves 22, which can be coaxially penetrated by pins 23, to collectively form a hinge section 20 for the hinged floating of adjacent stair sections 10, with the hinge axis parallel to the hinge axis of the hinge seat. Damping shafts are pre-embedded and fixed on the adjacent sidewalls of adjacent stair sections 10. Each damping shaft has a first hook portion 31 and a second hook portion 32 that rotatably engage with each other to form a James hook 30. The damping shafts (shaft structures with damping material on them) serve two purposes: firstly, they utilize their damping characteristics to prevent the first hook portions 31 and 32 from rotating, ensuring stability before engagement and guaranteeing a stable connection; secondly, they utilize the rotational characteristics of the first hook portions 31 and 32 when subjected to forces exceeding the damping force, allowing the maintenance staircase to float stably within a certain range without interference. Furthermore, the James hooks 30 are arranged in two symmetrical sets on the adjacent sides of adjacent stair sections 10. After the two James hooks 30 are installed, the axes of the first hinge sleeve 21 and the second hinge sleeve 22 are ensured to be parallel, providing technical support for subsequent convenient installation. The rotation axis of the hinge seat, the hinge axis of the hinge section 20, the axis of the damping shaft, and the James hook 30 are all parallel to the length direction of the horizontal step surface of the stair section 10, that is, the stair section 10 and the structural wall 50 can produce a hinged swinging motion.

[0039] The aforementioned Jan coupler 30 is a Jan coupler used in existing technology for connecting train carriages. Its principle is based on a crab-claw-like mechanical structure to achieve automatic locking and separation of carriages. Its core components include the coupler head, coupler tongue, and buffer device, and are manufactured using high-strength steel to ensure traction stability. Specific detailed connection structures and principles are existing technology and will not be elaborated here.

[0040] The maintenance staircase of this application, under the combined action of the aforementioned hinge joint 20 and James hook 30, can adaptively adjust its slope when subjected to continuous impact loads caused by water fluctuations. This allows for continued operation even under various conditions in the water. Simultaneously, the buffer device within the James hook 30 provides a buffering effect, converting impact force into controllable deformation and ensuring the structural safety and stability of the maintenance staircase. Furthermore, when the inclined wall of the structural wall 50 experiences slight hollow changes due to the weak scouring effect of water flow, maintenance personnel walking on these hollow areas can cause the maintenance staircase to adaptively adjust its angle under the weight of their footsteps, ensuring the bottom of the staircase fits as close as possible to the structural wall 50. Conversely, when the hollow areas of the structural wall 50 are larger, the James hook 30 limits the maximum adaptive adjustment angle of the maintenance staircase when personnel step on it, ensuring the staircase fits as close as possible to the structural wall 50 while preventing significant deformation and excessive swaying during walking. In addition, the floating mechanism formed by the hinge joint 20 and the James hook 30 also has good anti-slip and anti-shear stability and wave impact adaptive toughness.

[0041] Based on the above, such as Figure 3 As shown, the installation height of the James hook 30 is lower than that of the hinge joint 20. This results in the overall structural stiffness curve of the maintenance staircase being a double-broken line under the combined effect of the two connection functions of the hinge joint 20 and the James hook 30. Under low load, the hinge joint 20 dominates, while under high load, the James hook 30 intervenes, which can reduce the increase in stiffness and avoid brittle failure.

[0042] Based on the above, such as Figure 3 As shown, the first hinge sleeve 21 is fixed to the vertical step wall at the end of the stair section 10. The first hinge sleeve 21 includes a first fixing plate 211 fixed to the vertical step wall and a first sleeve 212 fixed to the first fixing plate 211, through which a pin 23 can pass coaxially. The first fixing plate 211 is bolted to the vertical step wall, and a first pre-embedded tenon 213 pre-embedded into the vertical step wall is also fixed on the first fixing plate 211.

[0043] The second hinge sleeve 22 is fixed on the horizontal step surface at the first end of the stair section 10. The second hinge sleeve 22 includes a second fixing plate 221 fixed to the horizontal step surface and a second sleeve 222 fixed on the second fixing plate 221 through which a pin 23 can pass coaxially. The second fixing plate 221 is bolted to the vertical step wall, and a second pre-embedded tenon 223 pre-embedded in the horizontal step surface is also fixed on the second fixing plate 221.

[0044] Both the first hinge sleeve 21 and the second hinge sleeve 22 are fixed to the stair section 10 using a fixing plate. In addition to bolt anchoring, pre-embedded tenons and mortises are also provided within the stair section 10, significantly enhancing the connection stability between the hinge sleeve and the stair section 10. Furthermore, the arrangement of fixing the first hinge sleeve 21 to the vertical step wall at the tail end of the stair section 10, and the second hinge sleeve 22 to the horizontal step surface at the head end of the stair section 10, ensures that both the first hinge sleeve 21 and the second hinge sleeve 22 are exposed within the worker's field of vision, facilitating accurate alignment of the two hinge sleeves during construction.

[0045] Based on the above, such as Figure 2 As shown, a hinge sleeve unit is formed by two first hinge sleeves 21 and a second hinge sleeve 22 located between them. At least two sets of these hinge sleeve units are arranged sequentially along the hinge axis of the hinge joint 20. Based on the fact that the first hinge sleeves 21 and the second hinge sleeves 22 can be easily and accurately aligned coaxially, this application provides a configuration of multiple hinge sleeve units, effectively enhancing the connection stability between adjacent stair sections 10.

[0046] Based on the above, such as Figure 2 As shown, the pin 23 includes a rod 231 that passes through the first hinge sleeve 21 and the second hinge sleeve 22, and a nut 232 threadedly connected to the tail of the rod 231. The head of the rod 231 has a protrusion, and the protrusion at the head of the rod 231 and the nut 232 at the tail restrict the separation of the pin 23 from the first hinge sleeve 21 and the second hinge sleeve 22. This pin 23 structure design allows for quick and convenient installation and high stability. In actual implementation, the pin 23 can also be a smooth rod structure, with separation restricted at both ends by R-pins.

[0047] Because the water flow may have slight fluctuations, the adaptive adjustment angle of the maintenance staircase may cause a minor impact on the staircase. To reduce this impact damage, such as... Figure 4 As shown, the vertical step walls at the near ends of adjacent stair sections 10 are arranged close together, and there is a floating interval between the two vertical step walls for the hinged floating of adjacent stair sections 10, and a buffer component 40 is provided at the floating interval. The buffer component 40 is set to avoid direct impact on the stair surface at the connection point when the angle changes, thus preventing damage, effectively extending the service life of the staircase, reducing the consumption cost of manpower and material resources for later maintenance, and achieving energy saving.

[0048] like Figure 2 and Figure 4As shown, the buffer assembly 40 includes a first buffer and a second buffer, which are respectively fixed to the vertical stair walls at the near ends of adjacent stair sections 10. The first buffer and the second buffer are both located on the same circumference with the hinge axis of the hinge section 20 as the center. This means that when the adaptive adjustment angle of the stair is being inspected, the collision buffer is between the first buffer and the second buffer, and the buffer structure does not need to act directly on the stair section 10, further reducing the damage to the stair section 10.

[0049] Specifically, both the first and second buffer components are made of rubber, silicone, or buffer springs, all of which possess good cushioning performance. For example... Figure 4 As shown, all of them are fixed to the vertical staircase wall by anchors. Since the buffer component 40 mainly bears the compressive force, the anchor in this embodiment can be a plate that is fixed to the staircase section 10 by bolts or pins.

[0050] It is worth mentioning that, in actual implementation, the preferred hinge joint 20 and James hook 30 of this application are both made of high-strength steel, ensuring the strength of the maintenance staircase of this application. Furthermore, the main material for each staircase section 10 is lightweight high-strength concrete with a strength grade of C40 or higher; the reinforcing steel is HRB400 grade threaded steel as the main reinforcement and HPB300 grade plain round steel as the distribution reinforcement. During fabrication, a high-precision steel mold is used for casting. In mold design, a CNC machine tool is used to process the steel combination mold, and the inner surface is sprayed with a high-polymer release agent to ensure that the flatness error of the formed surface is sufficiently small.

[0051] The assembly method of the aforementioned modular underwater maintenance staircase includes the following steps:

[0052] S1. Hinged and fixed the first stair section 10 to the upper part of the structural wall 50.

[0053] S2. Hoist the first end of the adjacent lower stair section 10 to the tail end of the adjacent upper stair section 10, and snap-fit ​​the first hook part 31 and the second hook part 32 of the James hook 30 at their near ends.

[0054] S3. Obviously, after the assembly of the James hook 30 in step S2 is completed, the axes of the first hinge sleeve 21 and the second hinge sleeve 22 are arranged in parallel. At this time, taking the snap-fit ​​assembled James hook 30 as the rotating floating node, the lower stair section 10 is quickly adjusted so that the axes of the first hinge sleeve 21 and the second hinge sleeve 22 are aligned. After that, the rod body 231 of the pin 23 is coaxially passed through the first hinge sleeve 21 and the second hinge sleeve 22, and the nut 232 is threaded onto the tail of the rod body 231.

[0055] S4. Install the adjacent lower stair sections 10 sequentially until the last stair section 10 and its adjacent upper stair section 10 are completed. At this point, if Figure 5As shown, the lower wall of the maintenance staircase, which consists of all the stair sections 10, is fitted to the structural wall 50, and the tail end of the last stair section 10 is finally hinged and installed on the lower part of the structural wall 50.

[0056] Unlike steel staircases with a welded, integrated structure, and also unlike traditional concrete staircases with a molded, integrated structure, the maintenance staircase of this application adopts a combined structure composed of multiple stair sections 10 hinged together.

[0057] This articulated assembly structure allows the bottom of the maintenance staircase to better conform to the inclined surface of the structural wall 50, while also enabling underwater assembly operations that are difficult to achieve with welding and integral casting in a wet environment. During assembly, simply assemble the stair sections 10 sequentially according to the staircase site, and complete the connection by impacting with the James hook 30. This allows for quick positioning and snapping without complex equipment, shortening the operation time. Subsequently, using the James hook 30 as a rotating floating node, the stair section 10 is adjusted to quickly and accurately align the first hinge sleeve 21 and the second hinge sleeve 22 coaxially, and finally, the pin 23 is inserted coaxially through, further ensuring the high efficiency of the assembly operation. Compared to traditional welding methods, this invention avoids the adverse environmental impact of some of the harmful gases produced during welding. Compared to integrated casting, it eliminates the need for cumbersome on-site assembly of casting molds and post-casting curing procedures. The maintenance staircase of this application moves the casting and curing of stair section 10 to the processing site in advance. The first hinge sleeve 21, the second hinge sleeve 22, and the James hook 30 are all pre-embedded and fixed at the processing site. Therefore, the stair section 10 can be used directly after being transported to the construction site, which can reduce cumbersome operations on the construction site, reduce noise, reduce the generation of harmful gases, and reduce the impact on the surrounding environment.

[0058] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0060] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A modular underwater maintenance stairway, characterized in that, The maintenance staircase is composed of at least two stair segments (10) connected in sequence, and the two ends of the maintenance staircase are respectively hingedly installed on the structural wall (50) through the hinged seat; the proximal ends of the adjacent stair segments (10) are respectively pre-buried and fixed with the first hinged sleeve (21) and the second hinged sleeve (22) which can be coaxially penetrated by the pin bolt (23), so as to jointly constitute the hinged segment (20) for the hinged floating of the adjacent stair segments (10); the proximal end side walls of the adjacent stair segments (10) are respectively pre-buried and fixed with the damping shaft, and the two damping shafts are respectively and reversibly fitted with the first hook part (31) and the second hook part (32) which are matched with each other and constitute the Jan hook (30), and the Jan hook (30) is arranged as two groups which are symmetrically arranged on the two sides of the proximal ends of the adjacent stair segments (10), the hinged axis of the hinged seat, the hinged axis of the hinged segment (20), the axis of the damping shaft and the central axis of the Jan hook (30) are all parallel to the length direction of the horizontal step surface of the stair segment (10); the installation height of the Jan hook (30) is lower than that of the hinged segment (20); the first hinged sleeve (21) is fixed on the vertical step wall of the tail end of the stair segment (10), and the first hinged sleeve (21) comprises the first fixed plate (211) fixed with the vertical step wall and the first sleeve (212) coaxially penetrated by the pin bolt (23) and fixed on the first fixed plate (211), the first fixed plate (211) is bolted and anchored with the vertical step wall, and the first fixed plate (211) is further fixed with the first pre-buried mortise and tenon part (213) pre-buried in the vertical step wall; the second hinged sleeve (22) is fixed on the horizontal step surface of the head end of the stair segment (10), and the second hinged sleeve (22) comprises the second fixed plate (221) fixed with the horizontal step surface and the second sleeve (222) coaxially penetrated by the pin bolt (23) and fixed on the second fixed plate (221), the second fixed plate (221) is bolted and anchored with the vertical step wall, and the second fixed plate (221) is further fixed with the second pre-buried mortise and tenon part (223) pre-buried in the horizontal step surface.

2. A modular underwater maintenance stair according to claim 1, characterized in that Two first hinged sleeves (21) and one second hinged sleeve (22) located between the two first hinged sleeves (21) constitute a hinged sleeve unit, and the hinged sleeve unit is arranged as at least two groups arranged in sequence along the hinged axis direction of the hinged segment (20).

3. A modular underwater maintenance stair according to claim 1, wherein, The pin bolt (23) comprises the rod body (231) penetrating the first hinged sleeve (21) and the second hinged sleeve (22) and the nut (232) screwed at the tail of the rod body (231), the head of the rod body (231) has a protrusion, and the separation of the pin bolt (23) from the first hinged sleeve (21) and the second hinged sleeve (22) is limited by the protrusion of the head of the rod body (231) and the nut (232) at the tail of the rod body (231).

4. A modular underwater maintenance stair according to claim 1, wherein, The vertical step walls of the proximal ends of the adjacent stair segments (10) are arranged in proximity, and there is a floating interval for the hinged floating of the adjacent stair segments (10) between the vertical step walls, and the floating interval is provided with the buffer assembly (40).

5. A modular underwater maintenance stair according to claim 4, wherein, The buffer assembly (40) comprises a first buffer and a second buffer fixed on the vertical stair walls of the proximal ends of the adjacent stair segments (10) respectively, and the first buffer and the second buffer are located on the same circle with the hinge axis of the hinge segment (20) as the center.

6. A modular underwater maintenance stair according to claim 5, wherein, The first buffer and the second buffer are rubber or silicone or buffer springs, and are fixed on the vertical stair walls by anchorages.

7. Assembly method applied to a modular underwater maintenance stair according to claim 1, characterized in that, The method comprises the following steps: S1, hinge-fixing the first stair segment (10) to the upper part of the structure wall (50); S2, hoisting the proximal end of the adjacent lower stair segment (10) to the tail end of the adjacent upper stair segment (10), and assembling the first hook part (31) and the second hook part (32) of the Jan hook (30) between the two; S3, taking the assembled Jan hook (30) as a rotating floating node, adjusting the lower stair segment (10) and aligning the axes of the first hinge sleeve (21) and the second hinge sleeve (22), then coaxially penetrating the rod body (231) of the pin bolt (23) through the first hinge sleeve (21) and the second hinge sleeve (22), and screwing the nut (232) at the tail of the rod body (231); S4, sequentially installing the adjacent lower stair segments (10) until the last stair segment (10) and the adjacent upper stair segment (10) are completed, at this time, the lower wall of the maintenance stair formed by all the stair segments (10) is arranged in close contact with the structure wall (50), and finally the tail end of the last stair segment (10) is hinge-installed at the lower part of the structure wall (50).

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