A method for sealing ultra-deep foundation pits with dewatering wells under water-rich soft foundation conditions

Abstract

The present invention discloses the technical field of drainage well plugging, specifically a drainage well plugging method for ultra-deep foundation pits under water-rich soft foundation conditions. After the water pump inside the drainage well is taken out, the present invention uses a hook made of discarded steel on site to quickly crimp and seal the tray and the sealing material, then injects glue between the drainage well and the steel casing, and after the glue injection, the sealing body is completely pressed to death on the inner wall of the drainage well, thereby achieving the drainage well plugging. Finally, the top of the steel casing is filled with micro-expansion concrete, fully welded and rust-proofed, and finally the drainage well is completely plugged, which can eliminate the construction of pressurized water-rich foundation with a large amount of backwater. For the plugging process of the drainage well in the structural bottom plate of pressurized water-rich silty soil, the new drainage well plugging technology can be easily installed and easily plugged after the drainage is completed, which can completely solve the stubborn problem of water seepage in the reserved hole of the drainage well and has good durability.

Description

Technical Field

[0001] The invention relates to the technical field of drainage well plugging, and in particular to a drainage well plugging method for an ultra-deep foundation pit under water-rich soft foundation conditions. Background Art

[0002] With economic development, cities are expanding, residential areas are becoming more concentrated, and high-rise buildings, many with underground garages, are proliferating. Excavation depths are typically at least 6-8 meters, and silty soils have a low seepage coefficient. Therefore, dewatering wells are necessary to ensure adequate dewatering of the foundation pit.

[0003] Conventional dewatering wells in sandy foundations are generally located within the post-cast zone of the base slab. However, the effective impact radius of dewatering wells in silty soil is approximately 20 meters, so dewatering wells must be arranged within the base slab structure. Due to the high return volume of water in silty soil rich in confined water, CN23688990U welds a steel cover inside the steel casing to achieve internal waterproofing of the dewatering well, uses a waterstop plate to complete the external waterproofing of the dewatering well, and uses a waterstop strip to complete the waterproofing treatment between the steel casing and the dewatering well. After the water in the dewatering well is pumped out, the return volume is large, and the untimely welding of the steel cover leads to poor structural durability. Summary of the Invention

[0004] The present invention discloses a method for sealing precipitation wells rich in pressurized water by welding steel covers for waterproofing, but the method cannot achieve rapid sealing, resulting in poor durability. Therefore, a method for sealing precipitation wells for ultra-deep foundation pits under water-rich soft foundation conditions is proposed. For the sealing process of precipitation wells in the structural bottom plate of silty soil rich in pressurized water, the new precipitation well sealing technology can be easily installed and can be quickly sealed after the precipitation is completed. It can completely solve the stubborn problem of water seepage in the reserved holes of precipitation wells and has good durability.

[0005] The inventors have obtained the following technical solution through practice and summary: a method for sealing an ultra-deep foundation pit using a dewatering well under water-rich soft foundation conditions, the method steps are as follows:

[0006] Step 1: A sealing material with a closed end is hooped on the outer bottom of the steel casing. A tray with a diameter that matches the inner diameter of the steel casing is cut from waste steel plates. A corresponding ear structure is welded between the inner wall of the steel casing and the top of the tray. The ear structure is made of scrap steel bars. There are at least three groups of ear structures that are evenly distributed. Two corresponding ear structures are connected by hooks. Both ends of the hook are provided with hook bodies, and the two hook bodies are connected by a threaded sleeve, or hook bodies are provided at both ends of the hook, and the hooks are made of on-site scrap steel bars.

[0007] Step 2: Reserve a 300mm diameter steel casing with a 3mm thick water-stop steel plate at the bottom plate of the structure. The top elevation of the steel casing should be 5cm higher than the bottom plate surface. Then tie the bottom plate reinforcement and reinforce the steel casing at the same time and pour concrete. After the concrete has completely set, put in a water pump to reduce the water;

[0008] Step 3: After the structure is capped and the basement roof is backfilled, remove the water pump and place it in a tray to hold the concrete. Use the threaded sleeve to properly adjust the distance between the two hooks to keep the supporting part on the tray and the sealing material at the bottom of the steel casing in a sealed and compressed state;

[0009] Or the supporting part on the tray and the sealing material at the bottom end of the steel casing are placed in a sealed and compressed state through multiple sets of hooks and hangers;

[0010] Then pour slightly expansive concrete of a higher strength grade and vibrate it to make it dense;

[0011] Step 4: Use a steel cover plate to weld the top of the steel casing and apply anti-rust paint. After the basement floor is poured, the steel casing can be concealed.

[0012] Preferably, the sealing material includes a mounting body installed at the bottom end of the steel casing, and the mounting body is connected to a sealing body 1 and a sealing body 2 arranged in a herringbone shape, the sealing body 1 is located on the inner side of the sealing body 2 and the sealing body 2 abuts against the inner wall of the precipitation well, the sealing body 1 is suitable for being sealed and installed between the tray and the steel casing after the supporting part takes effect, and the sealing body 2 is suitable for being further pressed onto the inner wall of the precipitation well after the sealing body 1 is installed between the tray and the steel casing.

[0013] Preferably, a glue injection port and an exhaust / glue port are provided inside the steel casing. The glue injection port is a stepped hole structure. The glue injection port and the exhaust / glue port are symmetrically distributed. A glue injector is installed at the glue injection port and a glue injection head is installed at the end of the glue injector. The glue injection head is suitable for matching with the glue injection port. A mounting structure is installed on the glue injector, and the glue injector is temporarily fixed to the inside of the steel casing through the mounting structure.

[0014] Preferably, a plug is installed at the exhaust / glue port, which includes two PE films adsorbed by electrostatic force, and the plug has two states. One state is that it is located inside the steel casing and is in the exhaust / glue state when located inside the steel casing. The other state is that the space between the steel casing and the precipitation well is filled with glue and the plug is located between the steel casing and the precipitation well, and is in the blocking state at this time.

[0015] Preferably, a groove is provided at the bottom of the glue injection port, and the glue outlet on the glue injection head is eccentrically arranged. When the bottom of the glue injection head is inserted into the groove, the glue outlet and the glue injection port are adapted to overlap.

[0016] Preferably, a sealing ring is provided on the glue injection head, and after the bottom of the glue injection head is inserted into the groove, the glue outlet is in a sealed state around it.

[0017] Preferably, a waterproof steel plate is installed at the bottom of the structural base plate and at the top of the precipitation well, a waterproof roll is bonded between the waterproof steel plate and the steel casing, the top of the waterproof roll is bonded to the lower side of the waterstop steel plate and at least completely wraps the lower surface of the waterstop steel plate, and a top support anti-slip component is installed between the waterproof steel plate and the waterstop steel plate to fix the waterproof roll.

[0018] Preferably, the anti-dropping member includes a first and a second collar symmetrically arranged up and down, and a scissors support adapted to support the first and second collars;

[0019] The structures of the first and second rings are the same. Both the first and second rings include a large ring, a small ring, and a connecting piece for connecting the large ring and the small ring. The cross-sections of the large ring and the small ring are both L-shaped right-angle structures.

[0020] The scissors brace includes a first support rod and a second support rod evenly arranged in the circumferential direction. Both are rod structures with adjustable lengths and are staggered in the circumferential direction. The two ends of the first support rod are respectively hinged to the large ring of the first collar and the small ring of the second collar. The two ends of the second support rod are respectively hinged to the large ring of the second collar and the small ring of the first collar.

[0021] The structure of the small ring is a plurality of arc-shaped connecting plates distributed at equal intervals, or the large ring and the small ring are arranged in a splicing structure.

[0022] Preferably, by adjusting the length of the support rod one and the support rod two, the large ring will be crimped and fixed to the waterproof membrane on the waterstop steel plate and the water-blocking steel plate, and the small ring will be crimped and fixed to the outside of the steel casing to prevent the waterproof membrane from shifting. At the same time, the small ring ensures the sealing effect of the top of the glue injection part. The waterproof membrane must be completed before glue injection.

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

[0024] After the water pump inside the precipitation well is taken out, the present invention uses a hook and a hanging part made of waste steel on site to quickly crimp and seal the tray and the sealing material, and then injects glue between the precipitation well and the steel casing. After the glue is injected, the sealing body is completely pressed to the inner wall of the precipitation well, thereby achieving high-quality sealing of the precipitation well. Finally, the top of the steel casing is filled with micro-expansive concrete and then fully welded and rust-proofed. Finally, the precipitation well is completely sealed, which can eliminate the construction of pressurized water-rich foundation with a large amount of backwater. For the sealing process of the precipitation well in the structural bottom plate of pressurized water-rich silty soil, the new precipitation well sealing technology can be easily installed and easy to seal after precipitation is completed. It can completely solve the stubborn problem of water seepage in the reserved hole of the precipitation well and has good durability.

[0025] Waterproof steel plates are installed at the bottom of the structural base plate and the top of the precipitation well, and waterproof membranes are laid between the waterproof steel plates, steel casing and water-stop steel plates. After adjusting the support rods 1 and 2 of the scissors support, the sleeve rings 1 and 2 are crimped and fixed to the corresponding positions. At the same time, the sealing degree of the top of the injection space can be ensured. After injection, the waterproof membrane and the injected sealant can be fully bonded. The comprehensive use ensures the high-quality anti-seepage effect of the precipitation well rich in pressurized water. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 Schematic diagram of the overall structure of an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the overall structure of an embodiment of the present invention;

[0029] Figure 4 for Figure 3 A partial enlarged view of point A in the middle;

[0030] Figure 5 for Figure 3 A partial enlarged view of point B in the middle;

[0031] Figure 6 for Figure 3 The enlarged view of the part at point B during or before injection;

[0032] Figure 7 for Figure 3 A partial enlarged view of point C in the middle;

[0033] Figure 8 for Figure 3 A partial enlarged view of point D in the middle;

[0034] Figure 9 Schematic diagram of the overall structure of an embodiment of the present invention;

[0035] Figure 10 for Figure 9 Schematic diagram of the partial structure of the middle top support anti-slip component;

[0036] Figure 11 for Figure 9 Schematic diagram of the overall structure of the middle top support anti-slip component. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships 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 direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0039] Example 1, as Figure 1 、 Figure 2 、 Figure 3 As shown, a method for sealing an ultra-deep foundation pit using a dewatering well under water-rich soft foundation conditions is described, and the method steps are as follows:

[0040] Step 1: A sealing material 10 with a closed end is hooped on the bottom of the outer side of the steel casing 1, and a tray 14 with a diameter that matches the inner diameter of the steel casing 1 is cut from waste steel plates. A corresponding ear structure 15 is welded to the inner wall of the steel casing 1 and the top of the tray 14. The ear structure 15 is made of scrap steel bars. There are at least three groups of ear structures 15 that are evenly distributed. Two corresponding ear structures 15 are connected by a hook 16. Both ends of the hook 16 are provided with a hook body 17, and the two hook bodies 17 are connected by a threaded sleeve 18, or hook bodies 17 are provided at both ends of the hook 16, and the hook 16 is made of on-site scrap steel bars.

[0041] Step 2: Reserve a steel casing 1 with a diameter of 140mm and a 3mm thick water-stop steel plate 2 at the position of the structural bottom plate 19. The top elevation of the steel casing 1 is 5cm higher than the surface of the structural bottom plate 19. Then tie the bottom plate steel bars and reinforce the steel casing 1 at the same time and pour concrete. After the concrete is finally set, put in a water pump for precipitation.

[0042] Step 3: After the structure is capped and the basement roof is backfilled, the water pump is removed and placed in a tray 14 to hold the concrete. The threaded sleeve 18 is used to appropriately adjust the distance between the two hooks 17 to place the supporting portion on the tray 14 and the sealing material 10 at the bottom of the steel casing 1 in a sealed and compressed state;

[0043] Alternatively, the supporting portion on the tray 14 and the sealing material 10 at the bottom end of the steel casing 1 are placed in a sealed and compressed state through multiple sets of hooks 16;

[0044] Then pour slightly expansive concrete of a higher strength grade and vibrate it to make it dense;

[0045] Step 4: Use a steel cover plate 20 to weld the top of the steel casing 1 and apply anti-rust paint. After the basement floor is poured, the steel casing 1 can be concealed.

[0046] After the water pump is taken out, the tray 14 hooked by the hooking member 16 is quickly passed through the ear structure 15 and the sealing material 10 in a vertical state, and then the corresponding ear structure 15 is hooked through the top of the hooking member 16, so that the tray 14 seals and compresses the sealing material 10 and installs it between the steel casing 1 and the tray 14, realizing a rapid sealing and plugging structure. Then, the steel casing 1 is sealed with micro-expansive concrete injected inside, and finally the steel cover plate 20 is welded to the top of the steel casing 1 to complete the final sealing process.

[0047] Based on the above embodiments, Figure 4 As shown, the sealing material 10 includes a mounting body 11 mounted on the bottom end of the steel casing 1. The mounting body 11 is connected to a sealing body 12 and a sealing body 2 13 arranged in a herringbone pattern. The sealing body 12 is located inside the sealing body 2 13 and the sealing body 2 13 abuts the inner wall of the precipitation well 21. The sealing body 12 is adapted to be sealed and mounted between the tray 14 and the steel casing 1 after the supporting portion acts. The sealing body 2 13 is adapted to be further pressed against the inner wall of the precipitation well 21 after the sealing body 12 is mounted between the tray 14 and the steel casing 1. This ensures that the sealing body 2 13 is consistently located between the precipitation well 21 and the steel casing 1 to form a waterproof structure.

[0048] Based on the above embodiments, Figures 5 to 7 As shown, the interior of the steel casing 1 is provided with a glue injection port 3 and an exhaust / glue port 4. The glue injection port 3 is a stepped hole structure. The glue injection port 3 and the exhaust / glue port 4 are symmetrically distributed and are both located near the top of the drainage well 21. A glue injector 5 is installed at the glue injection port 3, and a glue injection head 6 is installed at the end of the glue injector 5. The glue injection head 6 is suitable for adapting to the glue injection port 3. The glue injector 5 is installed with a mounting structure 7 (a hook made of discarded steel bar heads). The glue injector 5 is temporarily fixed to the interior of the steel casing 1 through the mounting structure 7. The glue injector 5 is connected to an external glue injection supply device, and the internal space is filled with sealant (polyurethane sealant), so that the sealing body 13 is further pressed against the inner wall of the drainage well 21, thereby ensuring a waterproof effect between the two and simplifying the cushion layer laying structure. The symmetrical distribution of the glue injection port 3 and the exhaust / glue port 4 facilitates filling the internal space of the two as much as possible, ensuring the durability of the structure. This glue injection process follows the action of sealing the bottom of the steel casing 1 and before pouring concrete.

[0049] A plug 8 is installed at the vent / glue port 4. The plug 8 includes two PE films adsorbed by electrostatic force. The plug 8 has two states: one is located inside the steel casing 1, in which it is in the vent / glue state; the other is located between the steel casing 1 and the drainage well 21 after the gap between the steel casing 1 and the drainage well 21 is filled with glue, in which case it is in the blocking state. When the plug 8 is located inside the steel casing 1 during glue injection, after the gap is filled with glue, the PE film is pushed back toward the outside of the steel casing 1, forcing it to be located outside the steel casing 1. The pressure of the outer glue effectively bends and deforms the two PE films. At the same time, due to the electrostatic force between the two PE films, the sealant is adsorbed on each other, thereby ensuring that the sealant is filled and the sealing body 2 13 is sealed on the inner wall of the drainage well 21.

[0050] Based on the above embodiments, Figure 7 As shown, the bottom of the glue injection port 3 is provided with a groove 9, and the groove 9 is suitable for mounting the glue injection head 6 up and down. The glue outlet on the glue injection head 6 is arranged eccentrically. When the bottom of the glue injection head 6 is inserted into the groove 9, the glue outlet and the glue injection port 3 are suitable for coinciding. The adaptation of the groove 9 and the glue injection head 6 ensures the stability of the structure and enables pressure injection of glue at the glue injection port 3.

[0051] Based on the above embodiment, the glue injection head 6 is provided with a sealing ring (not shown in the figure). After the bottom of the glue injection head 6 is inserted into the groove 9, the glue outlet is sealed. The sealing ring can ensure that there is no glue leakage from the glue injection outlet under pressure injection conditions.

[0052] Based on the above embodiments, Figures 9 to 11As shown, a waterproof steel plate 22 is installed at the bottom of the structural base plate 19 and at the top of the precipitation well 21, and a waterproof coil 23 is bonded between the waterproof steel plate 22 and the steel casing 1. The top of the waterproof coil 23 is bonded to the lower side of the water-stop steel plate 2 and at least completely wraps the water-stop steel plate 2. A top support and anti-slip component 24 is installed between the waterproof steel plate 22 and the water-stop steel plate 2, which is suitable for fixing the waterproof coil 23. The top support and anti-slip component 24 includes a ring 1 241 and a ring 2 242 symmetrically arranged up and down, and a scissors support 243 suitable for supporting between the two. The structures of the ring 1 241 and the ring 2 242 are the same. The ring 1 241 and the ring 2 242 both include a large ring 244, a small ring 246 and A connecting piece 245 is used to connect the large ring 244 and the small ring 246. The cross-section of the large ring 244 and the small ring 246 is an L-shaped right-angle structure. The scissors strut 243 includes a support rod 1 247 and a support rod 2 248 that are evenly arranged circumferentially. Both are rod structures with adjustable lengths and are staggered along the circumference. The two ends of the support rod 1 247 are respectively hinged to the large ring 244 of the ring 1 241 and the small ring 246 of the ring 2 242. The two ends of the support rod 2 248 are respectively hinged to the large ring of the ring 242 and the small ring 246 of the ring 1 241. The structure of the small ring 246 is a plurality of arc-shaped connecting plates distributed at equal intervals, or the large ring 244 and the small ring 246 are arranged in a splicing structure. By adjusting the length of support rod 1 247 and support rod 2 248, the large ring 244 can be crimped and fixed to the corresponding position of the waterproof membrane 23, and the small ring 246 can crimp and fix the waterproof membrane 23 to the outside of the steel casing 1 to prevent the waterproof membrane 23 from shifting. At the same time, the small ring 246 can ensure the sealing effect of the top of the glue injection part. The waterproof membrane 23 must be completed before the glue injection.

[0053] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The replacement may be a replacement of a portion of a structure, device, or method step, or it may be a complete technical solution. Any equivalent replacement or modification based on the technical solution and inventive concept of the present invention shall be covered by the scope of protection of the present invention.

Claims

1. A method for plugging an ultra-deep foundation pit with a dewatering well under water-rich soft foundation conditions, characterized in that: The steps are as follows: Step 1: A sealing material with a closed end is hooped on the outer bottom of the steel casing. A tray with a diameter that matches the inner diameter of the steel casing is cut from waste steel plates. A corresponding ear structure is welded between the inner wall of the steel casing and the top of the tray. The ear structure is made of scrap steel bars. There are at least three groups of ear structures that are evenly distributed. Two corresponding ear structures are connected by hooks. Both ends of the hook are provided with hook bodies, and the two hook bodies are connected by a threaded sleeve, or hook bodies are provided at both ends of the hook, and the hooks are made of on-site scrap steel bars. Step 2: Reserve a 300mm diameter steel casing with a 3mm thick water-stop steel plate at the bottom plate of the structure. The top elevation of the steel casing should be 5cm higher than the bottom plate surface. Then tie the bottom plate reinforcement and reinforce the steel casing at the same time and pour concrete. After the concrete has completely set, put in a water pump to reduce the water; Step 3: After the structure is capped and the basement roof is backfilled, remove the water pump and place it in a tray to hold the concrete. Use the threaded sleeve to properly adjust the distance between the two hooks to keep the supporting part on the tray and the sealing material at the bottom of the steel casing in a sealed and compressed state; Or the supporting part on the tray and the sealing material at the bottom end of the steel casing are placed in a sealed and compressed state through multiple sets of hooks and hangers; Then pour slightly expansive concrete of a higher strength grade and vibrate it to make it dense; Step 4: Use a steel cover plate to weld the top of the steel casing and apply anti-rust paint. After the basement floor is poured, the steel casing can be concealed; A waterproof steel plate is installed at the bottom of the structural base plate and at the top of the precipitation well. A waterproof coil is bonded between the waterproof steel plate and the steel casing. The top of the waterproof coil is bonded to the underside of the waterstop steel plate and at least completely wraps the lower surface of the waterstop steel plate. A top support and anti-slip piece is installed between the waterproof steel plate and the waterstop steel plate to fix the waterproof coil; The anti-dropping support member includes a first and a second collar symmetrically arranged up and down, and a scissor support adapted to support the first and second collars; The structures of the first and second rings are the same. Both the first and second rings include a large ring, a small ring, and a connecting piece for connecting the large ring and the small ring. The cross-sections of the large ring and the small ring are both L-shaped right-angle structures. The scissors brace includes a first support rod and a second support rod evenly arranged in the circumferential direction. Both are rod structures with adjustable lengths and are staggered in the circumferential direction. The two ends of the first support rod are respectively hinged to the large ring of the first collar and the small ring of the second collar. The two ends of the second support rod are respectively hinged to the large ring of the second collar and the small ring of the first collar. The structure of the small ring is a plurality of arc-shaped connecting plates distributed at equal intervals, or the large ring and the small ring are arranged in a splicing structure.

2. The method for sealing a dewatering well for an ultra-deep foundation pit under water-rich soft foundation conditions according to claim 1, characterized in that: The sealing material includes an installation body installed at the bottom end of the steel casing, and the installation body is connected to a sealing body 1 and a sealing body 2 arranged in a herringbone shape. The sealing body 1 is located on the inner side of the sealing body 2 and the sealing body 2 abuts against the inner wall of the precipitation well. The sealing body 1 is suitable for being sealed and installed between the tray and the steel casing after the supporting part takes effect, and the sealing body 2 is suitable for being further pressed onto the inner wall of the precipitation well after the sealing body 1 is installed between the tray and the steel casing.

3. The method for sealing a dewatering well for an ultra-deep foundation pit under water-rich soft foundation conditions according to claim 2, characterized in that: The steel casing is provided with a glue injection port and an exhaust / glue port. The glue injection port is a stepped hole structure and is symmetrically distributed. A glue injector is installed at the glue injection port and a glue injection head is installed at the end of the glue injector. The glue injection head is suitable for matching with the glue injection port. A mounting structure is installed on the glue injector, and the glue injector is temporarily fixed to the inside of the steel casing through the mounting structure.

4. The method for sealing a dewatering well for an ultra-deep foundation pit under water-rich soft foundation conditions according to claim 3, characterized in that: A plug is installed at the exhaust / glue port, which includes two PE films adsorbed by electrostatic force. The plug has two states. One state is that it is located inside the steel casing and is in the exhaust / glue state when located inside the steel casing. The other state is that the space between the steel casing and the precipitation well is filled with glue and the plug is located between the steel casing and the precipitation well, and is in the blocking state at this time.

5. The method for sealing a dewatering well for an ultra-deep foundation pit under water-rich soft foundation conditions according to claim 3, characterized in that: The bottom of the glue injection port is provided with a groove, and the glue outlet on the glue injection head is eccentrically arranged. When the bottom of the glue injection head is inserted into the groove, the glue outlet and the glue injection port are adapted to overlap.

6. The method for sealing a dewatering well for an ultra-deep foundation pit under water-rich soft foundation conditions according to claim 4, characterized in that: The glue injection head is provided with a sealing ring, and after the bottom of the glue injection head is inserted into the groove, the glue outlet is in a sealed state around it.

7. The method for sealing a dewatering well for an ultra-deep foundation pit under water-rich soft foundation conditions according to claim 1, characterized in that: By adjusting the length of the support rod one and the support rod two, the large ring will be crimped and fixed to the waterproof membrane on the waterstop steel plate and the water-blocking steel plate, and the small ring will be crimped and fixed to the outside of the steel casing to prevent the waterproof membrane from shifting. At the same time, the small ring ensures the sealing effect of the top of the glue injection part. The waterproof membrane must be completed before glue injection.

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