Sealing device and its installation structure

Abstract

The present invention belongs to the field of prestressed technology, and mainly relates to the anti-corrosion of steel strands in saddles. The sealing device includes a front sealing unit and a rear sealing unit that are connected as a whole and arranged at intervals. The front sealing unit is provided with a second injection hole connecting the front end of the front sealing unit and the airspace between the front and rear sealing units. The sealing material is fed into the cavity between the front sealing unit, the rear sealing unit, the steel strand and the seat body from the second injection hole and fills the gap therebetween, which can effectively ensure the sealing performance between the sealing device and the steel strand and the saddle body. When the two ends of the saddle body are respectively sealed and connected to the sealing device, the interior of the saddle body can reach an ideal vacuum state. When the anti-corrosion material is injected and the saddle is vacuumed, the anti-corrosion material can fill all the gaps in the saddle body, thereby ensuring the anti-corrosion effect of the steel strand in the saddle body.

Description

Technical Field

[0001] The invention belongs to the technical field of prestressing, and mainly relates to the anti-corrosion of steel strands in cable saddles. Background Art

[0002] Cable saddles are used to redirect prestressed steel strands. Commonly used at bridge towers, they allow the strands to pass from one side of the tower to the other without interruption, ensuring the continuity of the prestressed strands. The strands within the saddle are exposed and curved, requiring sealing material to be filled into the saddle and ensure a tight seal between the saddle ends and the strands.

[0003] Chinese patent CN102939420A discloses a sealing device. The sealing device 122 is sequentially provided with a front extrusion plate 500, a transition pad 501, a sealing pad 503, an extrusion pad 505, and a rear extrusion plate 507, from the outside in. The non-rigid sealing pad 503 primarily seals the interior of the saddle body 121, isolating it from the external environment. However, in actual use, it was found that the compression and deformation of the sealing pad 503, combined with the steel strands, failed to isolate the saddle body 121 from the external environment. The sealing material was unable to completely fill the internal cavity of the saddle body 121, leaving some of the steel strands exposed and open to the outside air. This caused the steel strands to rust and fail, impacting bridge safety.

[0004] To avoid the above situation, Chinese patent CN205954470U discloses a steering sealing device for a cable saddle of a low-tower cable-stayed bridge, comprising a transition plate 1, a rubber plate 2, and a pressure plate 3. The step hole 7 provided on the transition plate 1 is equipped with a sealing gasket 8. The rubber plate 2 has a wedge-shaped end face, and the rear end of the rubber plate 2 is slightly larger than the inner wall of the saddle component. This can improve the sealing effect at the joint between the rubber plate 2 and the inner wall of the saddle, but still cannot improve the sealing performance of the sealing device and the steel strand. Summary of the Invention

[0005] The object of the present invention is to provide a sealing device and an installation structure thereof that can overcome the defects of the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is:

[0007] A sealing device comprises a front sealing unit and a rear sealing unit connected as one body, each provided with a cable hole for a steel strand to pass through and a first injection hole for an anti-corrosion material to pass through; a limit block is provided between the front and rear sealing units to maintain a minimum distance between the two; the front sealing unit is provided with a second injection hole connecting the front end of the front sealing unit with the airspace between the front and rear sealing units; the cavity of the first injection hole is isolated from the airspace between the front and rear sealing units; the rear sealing unit comprises a rear sealing gasket which is in contact with the steel strand and the cable saddle to form a sealing fit.

[0008] A mounting structure for a sealing device, wherein the front end plate of a front sealing unit is connected to the end of a seat body of a saddle so that a rear sealing unit, a limit block and part of the front sealing unit are accommodated in the seat body of the saddle; a steel strand passes through the sealing device through a cable hole, and a rear sealing gasket is fitted with the outer peripheral surface of the steel strand and the inner wall surface of the seat body to form a surface seal, and sealing material is fed in from a second injection hole and fills the cavity between the front sealing unit, the rear sealing unit, the steel strand and the seat body; after the sealing material solidifies, the outer end of the sealing device is isolated from the internal cavity of the seat body.

[0009] Compared to the prior art, the present invention has the following technical advantages: Sealing material is injected between the saddle body and the sealing device through the second injection hole, filling the gaps between the sealing device, the steel strand, and the saddle body with the sealing material, effectively ensuring the sealing performance between the sealing device, the steel strand, and the saddle body. When both ends of the saddle body are sealed with the sealing device, the interior of the saddle body can achieve an ideal vacuum state. While the anti-corrosion material is being injected, the saddle body is simultaneously vacuumed, allowing the anti-corrosion material to fill all gaps in the saddle body, thereby ensuring the anti-corrosion effect on the steel strand within the saddle body. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The following is a brief description of the contents and symbols in the drawings of this specification:

[0011] Figure 1 It is a three-dimensional schematic diagram of the sealing device during assembly;

[0012] Figure 2 yes Figure 1 A partial enlarged schematic diagram;

[0013] Figure 3 It is a three-dimensional schematic diagram of the sealing device when it is assembled on the saddle;

[0014] Figure 4 is a three-dimensional schematic diagram of the sealing device;

[0015] Figure 5 It is a cross-sectional schematic diagram of the sealing device when assembled on the saddle;

[0016] Figure 6 is a cross-sectional schematic diagram when the sealing material is injected from the second injection hole;

[0017] Figure 7 yes Figure 6 A partial enlarged schematic diagram;

[0018] Figure 8 It is a cross-sectional schematic diagram when the anti-corrosion material is injected from the first injection hole;

[0019] Figure 9 yes Figure 8 A partial enlarged schematic diagram.

[0020] In the figure: 11. front sealing unit, 111. front end plate, 112. front pressure plate, 113. front sealing gasket, 114. front transition gasket, 12. rear sealing unit, 121. rear pressure plate, 122. rear end plate, 123. rear sealing gasket, 124. rear transition gasket, 13. cable threading hole, 14. first injection hole, 15a. first limit block, 15b. second limit block, 151. first through hole, 16. second injection hole, 20. steel strand, 21. outer sheath, 30. cable saddle, 31. seat body, 33. cable threading channel, 41. solidified sealing material. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention will be further described in detail below through description of embodiments in conjunction with the accompanying drawings. Example 1

[0022] A sealing device includes a front sealing unit 11 and a rear sealing unit 12, which are integrally connected. In this embodiment, the front and rear sealing units 11 and 12 are connected by bolts. The front and rear sealing units 11 and 12 are each provided with a hole for the passage of a connecting bolt, which passes through the hole to connect the front and rear sealing units 11 and 12. The front and rear sealing units 11 and 12 are each provided with a cable hole 13 for the passage of a steel strand 20 and a first injection hole 14 for the passage of an anti-corrosion material. In other words, the cable hole 13 and the first injection hole 14 connect the two ends of the sealing device 10.

[0023] The front and rear sealing units 11 and 12 are arranged at intervals and a limit block is provided between them. The limit block abuts against the adjacent surfaces of the front and rear sealing units 11 and 12 to maintain the minimum distance between them. The front sealing unit 11 is provided with a second injection hole 16 connecting the front end of the front sealing unit 11 and the gap between the front and rear sealing units 11 and 12. Figure 5 As shown, for the convenience of assembly, the sealing device whose part extends into the saddle 30 is matched with the inner wall surface clearance of the saddle seat body 31. In order to prevent the anti-corrosion material from seeping out from the circumferential gap between the two, after the sealing device is connected to the end of the saddle 30, the sealing material is fed into the airspace enclosed by the front sealing unit 11, the rear sealing unit 12 and the saddle seat 31 from the second injection hole 16. The sealing material blocks the gap between the front sealing unit 11, the rear sealing unit 12 and the inner wall of the seat body 31, which can effectively ensure the circumferential sealing effect of the sealing device and the inner wall of the saddle seat body 31.

[0024] To prevent sealing material from entering the interior of the saddle 31 through the gap between the outer periphery of the rear sealing unit 12 and the base 31, or the gap between the cable insertion hole 13 on the rear sealing unit 12 and the steel strand 20, the rear sealing unit 12 includes a rear sealing gasket 123 that forms a seal with the steel strand 20 and the cable saddle base 31. That is, when the sealing device is connected to the cable saddle base 31, the rear sealing gasket 123 forms a circumferential surface seal with the inner wall of the base 31; when the steel strand 20 passes through the cable insertion hole 13, the rear sealing gasket 123 forms a circumferential surface seal with the steel strand 20. Specifically, in this embodiment, the rear sealing unit 12 is composed of several plate-like components, including a rear pressure plate 121, a rear end plate 122, and a rear sealing gasket 123 sandwiched therebetween. The plate profiles of the rear pressure plate 121, the rear end plate 122, and the rear sealing gasket 123 are substantially identical. In this way, the rear sealing gasket 123 will be deformed by the compression of the rear pressure plate 121 and the rear end plate 122. The deformed rear sealing gasket 123 will protrude radially outwards and fit into the adjacent object, thus achieving a preliminary seal and preventing gas or liquid from entering the rear end of the rear sealing gasket 123. Figure 5 、 6 As shown, the rear sealing gasket 123 has a certain thickness. A force is applied to the sealing device 10 assembled at the end of the seat body 31 along its thickness direction to make the rear pressure plate 121 and the rear end plate 122 move toward each other. The rear sealing gasket 123 sandwiched between the rear pressure plate 121 and the rear end plate 122 is squeezed by the plate body and deformed to protrude outward so as to form a sealing fit with the seat body 31 and the steel strand 20. In this way, after the sealing material is injected between the front sealing unit 11 and the rear sealing unit 12 from the second injection hole 16, the sealing material can only fill the gap at the outer end of the rear sealing gasket 123.

[0025] To prevent the sealing material from filling the interior of the saddle 31 through the first injection hole 14, the cavity of the first injection hole 14 should be isolated from the airspace between the front and rear sealing units 11 and 12. In this embodiment, a tube is used to penetrate and connect the front and rear sealing units 11 and 12. In this way, the lumen of the tube constitutes the first injection hole 14 and can connect the two ends of the sealing device 10.

[0026] The front sealing unit 11 includes a front end plate 111 , a connecting flange 32 is provided at the end of the cable saddle body 31 , and a cable passage 33 is provided inside for the steel strand 20 to pass through.

[0027] When this embodiment is installed on the saddle 30, as shown in the attached Figure 5-9 As shown, first connect the front end plate 111 of the front sealing unit 11 and the connecting flange 32 of the saddle 30, so that the rear sealing unit 12, the limit block and part of the front sealing unit 11 are accommodated in the seat 31 of the saddle 30. Then, the steel strand 20 is threaded through the threading hole 13 and passes through the sealing device 10. Figure 1As shown, the two ends of the saddle 30 are connected to the sealing device 10 respectively. After the steel strand 20 passes through the cable holes 13 on the sealing device 10 at both ends of the saddle 30, as shown in the attached figure, Figure 6 As shown, the rear pressure plate 121 and the rear end plate 122 are squeezed to deform the rear sealing gasket 123 and form a sealing fit with the inner wall surface of the seat body 31 and the outer peripheral surface of the steel strand 20. The sealing material is then fed in from the second injection hole 16 and fills the airspace between the front sealing unit 11, the rear sealing unit 12, the steel strand 20 and the seat body 31. The sealing material overflows from the hole or gap at the end surface of the sealing device 10, indicating that the sealing material has filled the outer end gap of the rear sealing gasket 123.

[0028] The sealing material has a certain fluidity when injected into the sealing device. After being injected into the airspace for a certain period of time, it solidifies and seals the gap. After the sealing material solidifies, it can isolate the chambers on the front and rear sides of the seat body 31 on the rear sealing gasket 123, thereby meeting the vacuum sealing requirements. The sealing material used in this embodiment is polyurethane, which expands slightly after solidification and has a low adhesion force. The expansion of the sealing material can ensure its sealing performance, and the low adhesion force facilitates the replacement of the steel strand 20. Since the steel strand 20 may cause a certain deviation of the sealing device 10 after tensioning, in other embodiments, the sealing material can also be injected into the airspace enclosed by the front sealing unit 11, the rear sealing unit 12, the steel strand 20 and the seat body 31 after the initial tensioning or tensioning of the steel strand 20 is completed, so as to ensure its sealing performance. After the sealing device 10 at both ends of the seat body 31 is well sealed with the seat body 31 and the steel strand 20, as shown in the attached Figure 8 As shown, anti-corrosion material is injected into the saddle body 31 from one end thereof through the first injection hole 14 on the sealing device 10, and the other end of the saddle body 31 is connected to a vacuum pump to remove gas and moisture from the saddle body 31. When the anti-corrosion material overflows from the first injection hole 14 of the sealing device 10 located at the other end of the saddle body 31, the first injection holes 14 on the sealing devices 10 at both ends of the saddle body 31 are sealed, completing the anti-corrosion operation of the saddle 30.

[0029] The sealing device 10 of this embodiment is provided with a gap for accommodating sealing material between the front and rear sealing units 11 and 12. During specific implementation, after the sealing device 10 is installed on the cable saddle 30 and the cable threading or tensioning operation of the steel strand 20 is completed, the sealing material is injected into the gap between the front and rear sealing units 11 and 12. This not only facilitates the installation of the sealing device 10, but also enables the sealing material to fully fill the gaps between the sealing device 10, the steel strand 20 and the seat body 31, and match the contour of the gap, thereby effectively avoiding the problem that prefabricated flexible sealing materials such as sealing rubber sleeves and sealing rubber rings are subjected to uneven force in the assembled state, causing local areas to separate from the seat body 31 or the steel strand 20, or the local areas to be subjected to excessive stress and easily worn, resulting in sealing failure.

[0030] It should also be noted that the steel strands 20 located within the saddle 30 are exposed and require anti-corrosion treatment. The anti-corrosion material used in this embodiment is initially liquid, exhibits good fluidity, and has a lower viscosity than the sealing material. After a certain period of time, it solidifies, and the curing time is longer than that of the sealing material. The rear sealing gasket 123, after being squeezed and deformed by the rear pressure plate 121 and rear end plate 122, forms a surface seal or line seal with the saddle body 31 and the steel strands 20. However, the sealing effect does not achieve vacuum sealing. Because the saddle 31 is high in the middle and low at both ends, the rear sealing gasket 123 can only prevent the anti-corrosion material from escaping from the gaps between the components. However, due to its inherent properties, the anti-corrosion material cannot remain at the top of the saddle 31. As a result, the top of the saddle 30 at the middle and high point cannot be fully filled with the anti-corrosion material, leaving residual air inside the saddle 30. This makes it impossible to guarantee the anti-corrosion performance of the steel strands 20 at the high point within the saddle 30, and thus the service life of the steel strands 20, creating a safety hazard for the project. Therefore, in this embodiment, the front end of the rear sealing gasket 123 is filled with sealing material. After the sealing material filled in the sealing devices at both ends of the saddle 30 solidifies, the saddle body of the saddle 30 located between the sealing devices can reach a vacuum sealing condition. In this way, the saddle 30 is vacuumed while the anti-corrosion material is injected, so that the anti-corrosion material can enter the tiny gap to fill all the cavities inside the saddle 30, thereby expelling all the air inside the saddle 30 and achieving a good anti-corrosion effect. Example 2

[0031] The difference between this embodiment and the first embodiment is that the front sealing unit 11 is composed of several plate-shaped components. The front sealing unit 11 includes a front end plate 111, a front pressure plate 112, and a front sealing gasket 113 sandwiched between the two. The plate profiles of the front end plate 111, the front pressure plate 112, and the front sealing gasket 113 are basically the same. The front sealing gasket 113 can be deformed by the compression of the front end plate 111 and the front pressure plate 112. After deformation, the front sealing gasket 113 protrudes radially outward and can fit with the adjacent object to achieve preliminary sealing. Figure 5 、 6As shown, the front sealing gasket 113 has a certain thickness, which drives the front end plate 111 and the front pressure plate 112 to move toward each other, so that the front sealing gasket 113 sandwiched between the front end plate 111 and the front pressure plate 112 is squeezed by the plate body and deformed and protruded outward to form a sealing fit with the seat body 31 and the steel strand 20. In a specific implementation, tightening the connecting bolts causes the front sealing gasket 113 and the rear sealing gasket 123 to deform respectively and seal with the seat body 31 and the steel strand 20. In this way, the airspace between the front sealing unit 11, the rear sealing unit 12, the seat body 31 and the steel strand 20 can only communicate with the outside world through the second injection hole 16. The sealing device 10 needs to be provided with at least two second injection holes 16. The sealing material is injected from one second injection hole 16. When the sealing material overflows from the other second injection hole 16, it means that the area between the two injection holes is filled with the sealing material. After the sealing material solidifies, the anti-corrosion material can be injected into the seat body 31.

[0032] To ensure effective filling of the sealing and anti-corrosion materials, the second injection holes 16 are arranged in a high-low configuration. Specifically, when the sealing material is injected from the lower injection hole, if the sealing material overflows from the higher injection hole, it indicates that the sealing material level is not lower than that of the higher injection hole. Therefore, as long as the higher injection hole is positioned above the desired sealing area, a sealing effect can be guaranteed. Similarly, the first injection hole 14 for injecting the anti-corrosion material should also be arranged in a high-low configuration. Specifically, while ensuring a seal between the sealing device 10 and the seat body 31, the anti-corrosion material is injected at a low position at one end of the saddle 30. When the anti-corrosion material overflows from a higher position at the other end of the saddle 30, it indicates that the anti-corrosion material has filled the internal space of the seat body 31. In order to ensure the versatility of the sealing device 10 in this embodiment, two first injection holes 14 arranged at different heights are provided on the sealing device 10. During the specific implementation, the first injection hole 14 at a higher position on the sealing device 10 at the injection end of the saddle 30 and the first injection hole 14 at a lower position on the sealing device 10 at the other end of the saddle 30 are blocked, so as to ensure the convenient and reliable filling of the anti-corrosion material.

[0033] To facilitate assembly and prevent the stopper from separating from the front and rear pressure plates 112 and 121 or from falling out from between the front and rear sealing units 11 and 12, thereby preventing the spacing between the front and rear sealing units 11 and 12 from being maintained, in this embodiment, the front and rear pressure plates 112 and 121 are made of metal and welded together to form an integral body. In other embodiments, the front and rear pressure plates 112 and 121 may also be an integrally formed structure.

[0034] Specifically, in this embodiment, the stoppers include first and second tubular stoppers 15a and 15b. The first stopper 15a transitions between the front and rear sealing units 11 and 12, with the tubular aperture of the first stopper 15a forming the middle section of the first injection hole 14. The second stopper 15b is located at the rear end of the second injection hole 16, connecting the second injection hole 16 with the airspace between the front and rear sealing units 11 and 12. In other words, the stoppers in this embodiment both maintain the minimum spacing between the front and rear sealing units 11 and 12 and form an inlet channel for the sealing or anti-corrosion material. The stoppers forming the inlet channel for the sealing or anti-corrosion material are necessarily arranged at different heights relative to the first and second injection holes 14 and 16. In this embodiment, two second limit blocks 15b are provided corresponding to the second injection holes 16. The second limit block 15b at the lower position is provided below the lowest-position rope hole 13, and the second limit block 15b at the higher position is provided above the highest-position rope hole 13. If the line connecting the hole centers of the two second injection holes 16 is located within the plumb plane, then when the sealing material overflows from the high-position injection hole, there may be areas on the sides of the second injection holes 16 that have not yet been filled with the sealing material. Therefore, in order to ensure the filling effect of the sealing material, in this embodiment, the hollow line connecting the two second injection holes 16 is arranged at an angle to the plumb line, and the line connecting the tube centers of the second limit blocks 15b is also arranged at an angle to the plumb line. The specific embodiment of this embodiment is shown in the attached figure. Figure 3 、 4 As shown, the cable hole 13 is arranged in the middle of the sealing device 10 in a square area, and the two second injection holes 16 are located outside the two diagonal corners of the square area. In this way, the sealing material is injected from the second injection hole 16 located at the lower position.

[0035] This embodiment is shown in the attached Figure 6-9 As shown, the first and second limit blocks 15a, 15b are generally stepped tubes with a large middle section and small ends. The end faces of the large diameter sections of the first and second limit blocks 15a, 15b respectively abut against the adjacent components of the front and rear sealing units 11, 12, and the small diameter sections are inserted into the holes arranged in the adjacent components of the front and rear sealing units 11, 12. Among them, the second limit block 15b is located between the front and rear sealing units 11, 12 and has a first through hole 151 for the passage of sealing material. As shown in the attached figure Figure 6 、 7 As shown, in this embodiment, the opening of the first through hole 151 of the second limit block 15b located at a low position faces downward, and the opening of the first through hole 151 of the second limit block 15b located at a high position faces upward, so that the sealing material can fill the gap, thereby ensuring the sealing effect between the sealing device 10 and the saddle 31 and the steel strand 20.

[0036] The installation structure of the sealing device 10 of this embodiment is shown in the attached Figure 5 、 6As shown, the front end plate 111 is connected to the end of the base 31 of the saddle 30, so that the rear sealing unit 12, the limit block, and part of the front sealing unit 11 are accommodated in the base 31 of the saddle 30. The steel strand 20 passes through the sealing device 10 through the cable hole 13. The front sealing gasket 113 is squeezed by the front end plate 111 and the front pressure plate 112, deforming and abutting the outer peripheral surface of the steel strand 20 and the inner wall of the base 31 to form a surface seal. The rear sealing gasket 123 is squeezed by the rear pressure plate 121 and the rear end plate 122, deforming and abutting the outer peripheral surface of the steel strand 20 and the inner wall of the base 31 to form a surface seal. Sealing material is introduced from the second injection hole 16 and fills the cavity between the front sealing unit 11, the rear sealing unit 12, the steel strand 20, and the base 31. After the sealing material solidifies, it isolates the outer end of the sealing device 10 from the internal cavity of the base 31.

[0037] The base 31 of the saddle 30 is provided with a cable passage 33 for the steel strand 20 to pass through and maintain its position. The outer sheath 21 of the steel strand 20 extends into the base 31 through the cable passage hole 13. The end of the outer sheath 21 is located at the rear end of the rear sealing gasket 123 and the front end of the cable passage 33. The front and rear sealing gaskets 113 and 123 seal with the outer sheath 21 of the steel strand 20. This ensures that the exposed steel strand 20 is located in the cavity filled with the anti-corrosion material, effectively ensuring the anti-corrosion effect of the steel strand 20 and extending its service life. Example 3

[0038] The difference between this embodiment and the second embodiment is that a front transition pad 114 is sandwiched between the front end plate 111 and the front pressure plate 112, and a rear transition pad 124 is sandwiched between the rear pressure plate 121 and the rear end plate 122. Figure 6 As shown, the front and rear transition pads 114 and 124 are arranged away from the limit blocks, the front transition pad 114 is clamped between the front end plate 111 and the front rubber pad 113, and the rear transition pad 124 is clamped between the rear rubber pad 123 and the rear end plate 122, and the thickness of the front transition pad 114 is greater than that of the rear transition pad 124.

[0039] In this embodiment, the front and rear sealing pads 113 and 123 are made of an elastic material, the front and rear transition pads 114 and 124 are made of a polymer material, the front end plate 111, the front pressure plate 112, the stopper, the rear pressure plate 121, and the rear end plate 122 are made of a metal material, and the bolts 17 sequentially penetrate the front and rear sealing units 11 and 12 and are threadedly connected to the rear end plate 122. Tightening the bolts 17 causes the front end plate 111 and the rear end plate 122 to move toward each other, thereby applying a force to the front and rear rubber pads 113 and 123, causing them to deform.

[0040] The specific details of this embodiment are as shown in the attached Figure 3As shown, the front end plate 111 is in the shape of a ring plate. The middle part of the front end plate 111 is a through hole in the shape of a square. There are eight bolts 17 arranged around the through hole at intervals in the circumference. The first and second injection holes 14 and 16 are also arranged on the outer periphery of the through hole. Figure 2 As shown, in this embodiment, a first plug 141 is used to block the first injection hole 14, and a second plug 161 is used to block the second injection hole 16; the front end plate 111 is connected to the connecting flange 32 of the saddle 30 by means of mounting screws 18. The mounting screws 18 are located outside the bolts 17, the first injection hole 14, and the second injection hole 16, and are arranged circumferentially around the plate body of the front end plate 111.

Claims

1. A sealing device, characterized in that: A front sealing unit (11) and a rear sealing unit (12) are connected as one body, and the front sealing unit (11) and the rear sealing unit (12) are provided with a cable hole (13) for the steel strand (20) to pass through and a first injection hole (14) for the anti-corrosion material to pass through; a limit block is provided between the front and rear sealing units (11, 12) to maintain a minimum distance between the two; the front sealing unit (11) is provided with a second injection hole (16) connecting the front end of the front sealing unit (11) and the airspace between the front and rear sealing units (11, 12); the cavity of the first injection hole (14) is isolated from the airspace between the front and rear sealing units (11, 12); the rear sealing unit (12) includes a rear sealing gasket (123) that is in contact with the steel strand (20) and the seat (31) of the cable saddle (30) to form a sealing fit; The limiting block comprises a first limiting block (15a, 15b) and a second limiting block (15a, 15b) which are tubular as a whole. The first limiting block (15a) transitionally connects the front and rear sealing units (11, 12). The tube hole of the first limiting block (15a) constitutes the middle hole body of the first injection hole (14). The second limiting block (15b) is arranged at the rear end of the second injection hole (16). The second limiting block (15b) communicates with the airspace between the second injection hole (16) and the front and rear sealing units (11, 12). The two second limit blocks (15b) are arranged in a high and low arrangement, the second limit block (15b) at the low position is arranged below the lowest cable hole (13), and the second limit block (15b) at the high position is arranged above the highest cable hole (13); the two second limit blocks (15b) are arranged at an angle between a line connecting the tube cores and a plumb line; The first and second limiting blocks (15a, 15b) are generally in the form of stepped tubes with a large middle section and small ends. The end faces of the large diameter sections of the first and second limiting blocks (15a, 15b) respectively abut against the adjacent components of the front and rear sealing units (11, 12), and the small diameter sections are inserted into holes corresponding to the adjacent components of the front and rear sealing units (11, 12). The second limiting block (15b) is provided with a first through hole (151) on the tube body located between the front and rear sealing units (11, 12) for the passage of sealing material. The front sealing unit (11) includes a front end plate (111), a front pressure plate (112), and a front sealing gasket (113) sandwiched between the two, and the front sealing gasket (113) is deformed by the compression of the front end plate (111) and the front pressure plate (112); the rear sealing unit (12) includes a rear pressure plate (121), a rear end plate (122), and a rear sealing gasket (123) sandwiched between the two, and the rear sealing gasket (123) is deformed by the compression of the rear pressure plate (121) and the rear end plate (122); A front transition pad (114) is sandwiched between the front end plate (111) and the front pressure plate (112), and a rear transition pad (124) is sandwiched between the rear pressure plate (121) and the rear end plate (122). The thickness of the front transition pad (114) is greater than the thickness of the rear transition pad (124). The front and rear transition pads (114, 124) are arranged away from the limit block. The front and rear sealing pads (113, 123) are made of elastic material, and the front and rear transition pads (114, 124) are made of polymer material. The front end plate (111), the front pressure plate (112), the limit block, the rear pressure plate (121), and the rear end plate (122) are made of metal material. Bolts (17) sequentially penetrate the front and rear sealing units (11, 12) and are threadedly connected to the rear end plate (122).

2. The sealing device according to claim 1, characterized in that: The front pressing plate (112), the limiting block, and the rear pressing plate (121) are fixedly connected as one body.

3. An installation structure using the sealing device according to claim 1, characterized in that: The front end plate (111) of the front sealing unit (11) is connected to the end of the base body (31) of the saddle (30) so that the rear sealing unit (12), the limit block and part of the front sealing unit (11) are accommodated in the base body (31) of the saddle (30); the steel strand (20) passes through the sealing device (10) through the cable hole (13); the rear sealing gasket (123) is in contact with the outer peripheral surface of the steel strand (20) and the inner wall surface of the base body (31) to form a surface seal; the sealing material is fed from the second injection hole (16) and fills the cavity between the front sealing unit (11), the rear sealing unit (12), the steel strand (20) and the base body (31); after the sealing material is solidified, the outer end of the sealing device (10) and the internal cavity of the base body (31) are isolated.

4. An installation structure using the sealing device according to claim 1, characterized in that: The front end plate (111) is connected to the end of the seat body (31) of the cable saddle (30) so that the rear sealing unit (12), the limit block and part of the front sealing unit (11) are accommodated in the seat body (31) of the cable saddle (30); the steel strand (20) passes through the sealing device (10) through the cable hole (13), and the front sealing gasket (113) is deformed by the compression of the front end plate (111) and the front pressure plate (112) and is in contact with the outer peripheral surface of the steel strand (20) and the inner wall surface of the seat body (31) to form a surface seal. The rear sealing gasket (123) is deformed by the compression of the rear pressure plate (121) and the rear end plate (122) and fits with the outer peripheral surface of the steel strand (20) and the inner wall surface of the seat body (31) to form a surface sealing fit. The sealing material is fed from the second injection hole (16) and fills the cavity between the front sealing unit (11), the rear sealing unit (12), the steel strand (20) and the seat body (31). After the sealing material is solidified, it isolates the outer end of the sealing device (10) from the internal cavity of the seat body (31).

5. The mounting structure according to claim 3 or 4, characterized in that: A cable passage (33) is provided in the seat body (31) for the steel strand (20) to pass through and maintain the posture of the steel strand (20). The outer sheath (21) of the steel strand (20) extends into the interior of the seat body (31) through the cable passage hole (13). The end of the outer sheath (21) is located at the rear end of the rear sealing pad (123) and the front end of the cable passage (33).

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