Open caisson bottom sealing auxiliary system and open caisson bottom sealing method

Abstract

The invention belongs to the technical field of underground engineering, and discloses an open caisson bottom sealing auxiliary system and an open caisson bottom sealing method. The open caisson bottom sealing auxiliary system comprises a splicing device and a covering film assembly. The splicing device is arranged on an inner well wall in the circumferential direction. The covering film assembly comprises a first covering film and a second covering film, the first covering film is provided with a first joint edge enclosed in the circumferential direction of the inner well wall, the second covering film is provided with a second joint edge, and the splicing device moves in the circumferential direction so that the second joint edge can be directly connected to the first joint edge; when the covering film assembly is in a sinking state, the first covering film wraps the inner well wall in a surrounding mode, and the second covering film is arranged on the inner well wall in a curled mode. The second joint edge is connected to the covering film assembly behind the first joint edge, the covering film assembly can be folded to a pouring state under the action of gravity, at the moment, the first covering film and the second covering film are both attached to the excavation face, and a closed pouring face is formed on the excavation face. According to the open caisson bottom sealing method, the bottom sealing quality of the open caisson can be improved, and construction efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering, and in particular to a caisson bottom sealing auxiliary system and a caisson bottom sealing method. Background Art

[0002] A caisson is a common shaft-shaped structure in underground engineering, usually used as the foundation of bridge piers or other structures; the basic principle of its sinking is to utilize the deadweight of the shaft and the friction between the shaft wall and the soil layer, and to dig soil inside the shaft so that the shaft gradually sinks in the soil layer.

[0003] After the caisson is sunk, the bottom of the caisson needs to be sealed to improve the stability and safety of the caisson. Before sealing the bottom, the inner wall of the well needs to be cleaned to remove the silt and sediment attached to the well wall, so as to improve the bonding quality between the bottom seal concrete and the well wall. The commonly used method for cleaning the well wall is to manually go down to the bottom of the well to clean the well wall, but this method has the problems of low cleaning efficiency and insufficient cleaning effect, and there is also a certain risk for caissons that need to be cleaned underwater. Summary of the invention

[0004] The purpose of the present invention is to provide a caisson bottom sealing auxiliary system and a caisson bottom sealing method, which can improve the bottom sealing quality of the caisson and accelerate the construction efficiency.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] Caisson bottom sealing auxiliary system, including:

[0007] A splicing device, wherein the splicing device is movably arranged on the inner wall of the caisson along the circumferential direction;

[0008] A covering film assembly, comprising a first covering film and a second covering film, wherein the first covering film has a first joint edge enclosed along the circumference of the inner well wall, and the second covering film has a second joint edge, the first joint edge and the second joint edge have the same length, and the splicing device can move along the circumference to connect the second joint edge to the first joint edge;

[0009] The covering film assembly has a sinking state and a casting state. When the covering film assembly is in the sinking state, the first covering film surrounds and covers the inner well wall, and the second covering film is rolled and arranged on the inner well wall;

[0010] The covering film assembly after the second joining edge is connected to the first joining edge can be folded to the casting state under the action of gravity. When the covering film assembly is in the casting state, the first covering film and the second covering film are both attached to the excavation surface and form a closed casting surface on the excavation surface.

[0011] Preferably, the first covering film has a free end and a fixed end, the fixed end is away from the wellhead and fixedly arranged at the upper end of the blade foot, the upper end of the blade foot is the end of the inner well wall close to the blade foot ring, the free end is close to the wellhead and is detachably connected to the inner well wall, and the first joining edge is arranged at the free end.

[0012] Preferably, a hanging ring is provided on the inner well wall, and the free end is attached to the hanging ring by a connecting rope.

[0013] Preferably, the splicing device can cut the connecting rope by moving circumferentially.

[0014] Preferably, the bottom sealing auxiliary system further comprises a bundling assembly, and when the covering film assembly is in the sinking state, the bundling assembly is used to fold and fix the second covering film to the inner well wall on the side of the first joint edge close to the wellhead.

[0015] Preferably, the bundling assembly includes an electromagnet, an adsorbent and a strap, the electromagnet is arranged on the inner well wall, one end of the strap is fixed to the inner well wall, the other end of the strap is provided with an adsorbent, the strap rests on the folded second covering film, and the electromagnet can adsorb the adsorbent when energized.

[0016] Preferably, a mud-isolating net is provided on the second covering film, and the mud-isolating net is used for filtering mud and sand on the excavation surface.

[0017] The caisson bottom sealing method, using the above-mentioned caisson bottom sealing auxiliary system, comprises the following steps:

[0018] S1, wrapping the first covering film around the inner well wall, and fixing the end of the first covering film away from the wellhead to the upper end of the blade foot, the upper end of the blade foot is the end of the inner well wall close to the blade foot ring, and connecting the end of the first covering film close to the wellhead to the inner well wall;

[0019] S2, rolling up the second covering film and setting it on the inner well wall, and installing the splicing device on the inner well wall;

[0020] S3, excavating the soil layer to sink the caisson to a specified depth;

[0021] S4, connecting the first joint edge and the second joint edge to the splicing device respectively, and driving the splicing device to move along the circumference of the inner well wall so that the second joint edge is directly connected to the first joint edge;

[0022] S5, removing the end of the first covering film close to the wellhead, so that the covering film assembly is folded to a casting state under the action of gravity;

[0023] S6. pouring bottom sealing concrete onto the casting surface.

[0024] Preferably, step S1 further comprises: brushing glue between the first covering film and the inner well wall.

[0025] Preferably, after removing the end of the first covering film close to the wellhead in step S5, the method further comprises:

[0026] A heavy object is placed on the covering film assembly.

[0027] The beneficial effects of the present invention are:

[0028] The caisson bottom sealing auxiliary system provided by the present invention comprises a splicing device and a covering film assembly, the covering film assembly comprises a first covering film and a second covering film, and the splicing device is movably arranged on the inner well wall of the caisson along the circumferential direction; because when the covering film assembly is in a sinking state, the first covering film surrounds and covers the inner well wall, so during the sinking process of the caisson, the first covering film plays a role of isolating the soil from the inner well wall, ensuring that the inner well wall within the pouring height range of the bottom sealing concrete is clean and free of mud when the caisson sinks, and the bonding quality of the bottom sealing concrete and the inner well wall can be guaranteed without manual cleaning of the wall, thereby greatly improving the construction efficiency and construction safety; because when the covering film assembly is in a pouring state, the first covering film and the second covering film are both attached to the excavation surface and form a The covering membrane assembly forms a closed casting surface, so the covering membrane assembly can effectively isolate the soil of the excavation surface, prevent the mud and sand on the excavation surface from mixing into the concrete when casting the bottom sealing concrete and affecting the quality of the bottom sealing, and improve the waterproof effect of the bottom sealing; because when the covering membrane assembly is in a sinking state, the second covering membrane is rolled up and arranged on the inner well wall, and therefore will not affect the excavation of the soil and the discharge of earthwork below the caisson; because when the covering membrane assembly is folded to the casting state, the splicing device will connect the second joint edge to the first joint edge directly, so the splicing device can completely splice the second covering membrane to the first covering membrane along the circumference of the inner well wall to form an enclosed whole, thereby ensuring that when the covering membrane assembly is attached to the excavation surface, a closed casting surface can be formed.

[0029] By using the caisson bottom sealing method, a first covering film is coated on the inner wall of the caisson, thereby preventing the caisson from adhering to the inner wall during the sinking process, ensuring that the inner wall of the caisson within the pouring height range of the bottom sealing concrete is clean and free of mud, and the bonding quality of the bottom sealing concrete and the inner wall can be guaranteed without manual cleaning of the wall, thereby greatly improving the construction efficiency and construction safety; and because when the covering film assembly is in a pouring state, the first covering film and the second covering film can be respectively attached to the excavation surface and form a closed pouring surface, the covering film assembly can effectively isolate the excavated soil, thereby preventing mud and sand on the excavation surface from being mixed into the concrete when pouring the bottom sealing concrete and affecting the bottom sealing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a covering membrane assembly provided by a specific embodiment of the present invention when it is in a sinking state;

[0031] Figure 2 is a schematic structural diagram of a first covering film and a second covering film provided in a specific embodiment of the present invention;

[0032] Figure 3 It is a side view of the caisson after the bottom sealing is completed provided by a specific embodiment of the present invention.

[0033] In the figure:

[0034] 100-caisson;

[0035] 1- Splicing device;

[0036] 2-track;

[0037] 3-covering membrane assembly; 31-first covering membrane; 32-second covering membrane; 321-mud screen;

[0038] 4- Hanging loop. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0040] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0042] In the description of this embodiment, the terms "upper", "lower", "right", "left" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0043] like Figure 1 and Figure 2 As shown, the present invention provides a caisson bottom sealing auxiliary system, which includes a splicing device 1 and a covering film assembly 3. The splicing device 1 is movably arranged on the inner wall of the caisson 100 along the circumferential direction; the covering film assembly 3 includes a first covering film 31 and a second covering film 32, the first covering film 31 has a first joint edge circumferentially enclosed along the inner wall, the second covering film 32 has a second joint edge, the first joint edge and the second joint edge are of the same length, and the splicing device 1 can move along the circumferential direction to connect the second joint edge to the first joint edge directly; the covering film assembly 3 has a sinking state and a casting state. When the covering film assembly 3 is in the sinking state, the first covering film 31 surrounds and covers the inner wall, and the second covering film 32 is curled and arranged on the inner wall; the covering film assembly 3 after the second joint edge is connected to the first joint edge can be folded to the casting state under the action of gravity. When the covering film assembly 3 is in the casting state, the first covering film 31 and the second covering film 32 are both attached to the excavation surface, and a closed casting surface is formed on the excavation surface.

[0044] In this embodiment, since the first covering film 31 surrounds and covers the inner well wall when the covering film assembly 3 is in a sinking state, the first covering film 31 plays a role of isolating the soil from the inner well wall during the sinking process of the caisson 100, ensuring that the inner well wall within the pouring height range of the bottom concrete is clean and free of mud when the caisson 100 sinks, and the bonding quality of the bottom concrete and the inner well wall can be guaranteed without manual cleaning of the wall, thereby greatly improving the construction efficiency and construction safety; since the first covering film 31 and the second covering film 32 are both attached to the excavation surface and form a closed pouring surface when the covering film assembly 3 is in a pouring state, the covering film assembly 3 can effectively isolate the soil on the excavation surface, avoiding The mud and sand on the excavation surface are mixed into the concrete when pouring the bottom sealing concrete, which affects the quality of the bottom sealing and improves the waterproof effect of the bottom sealing; because when the covering membrane assembly 3 is in a sinking state, the second covering membrane 32 is curled and arranged on the inner well wall, and therefore will not affect the excavation and earth discharge below the caisson 100; because when the covering membrane assembly 3 is folded to the pouring state, the splicing device 1 will connect the second joint edge to the first joint edge directly, so the splicing device 1 can completely splice the second covering membrane 32 to the first covering membrane 31 along the circumference of the inner well wall to form an enclosed whole, thereby ensuring that when the covering membrane assembly 3 is attached to the excavation surface, a closed pouring surface can be formed.

[0045] Specifically, the first covering film 31 is rectangular. When the covering film assembly 3 is in a sunken state, the second covering film 32 is folded and curled and arranged on the inner well wall. The first covering film 31 is circumferentially attached to the inner well wall to completely cover the inner well wall within the pouring height of the bottom concrete. The long side of the first covering film 31 close to the wellhead is the first joint side, and the vertical short side of the first covering film 31 is not less than the pouring height of the bottom concrete. When the covering film assembly 3 is in a pouring state, the second covering film 32 is released and connected to the first covering film 31 under the drive of the splicing device 1. The unfolded second covering film 32 is circular, and the circumference of the second covering film 32 is the second joint side, which is equal to the length of the first joint side of the first covering film 31. Therefore, when the first joint side and the second joint side are connected face to face, the second covering film 32 is completely spliced ​​at the end of the first covering film 31.

[0046] Specifically, the connection method between the first joining edge and the second joining edge can be set according to actual needs; illustratively, zipper teeth are provided on the first joining edge and the second joining edge, and the splicing device 1 includes a driving motor, a running wheel and a pulling head matching the chain teeth, the running wheel is connected to the driving motor, the pulling head is arranged on the running wheel, and the two ends of the pulling head are respectively connected to the first joining edge and the second joining edge, the driving motor can be remotely controlled to start and stop from the ground, and the pulling head can be remotely controlled from the ground to separate the first joining edge and the second joining edge, and a circumferential track 2 is provided on the inner well wall above the first joining edge, and the running wheel of the splicing device 1 is arranged on the track 2 and can move along the track 2 under the drive of the driving motor to pull the first joining edge and the second joining edge together, thereby forming a zipper structure.

[0047] Furthermore, the first covering film 31 has a free end and a fixed end, the fixed end is away from the wellhead and fixedly arranged at the upper end of the blade foot, the upper end of the blade foot is the end of the inner well wall close to the blade foot ring, the free end is close to the wellhead and is detachably connected to the inner well wall, and the first joint edge is arranged at the free end. Specifically, the fixed end is pre-embedded in the inner well wall, and the track 2 is arranged on the inner well wall above the free end; when the first covering film 31 is unfolded and the first joint edge and the second joint edge are connected by the splicing device 1, the staff removes the free end of the first covering film 31 from the inner well wall, and the second covering film 32 of the first covering film 31 can be folded down with the plane where the fixed end is located as the flipping surface under the action of its own gravity. While the first covering film 31 and the second covering film 32 are both covering the excavation surface, the first covering film 31 can also cover the side wall of the blade foot. In this embodiment, the first covering film 31 and the second covering film 32 are both a highly flexible polymer film made of polyetheretherketone. It has good flexibility and waterproofness.

[0048] Specifically, Figure 1 As shown, a hanging ring 4 is provided on the inner well wall, the free end is attached to the hanging ring 4 by a connecting rope, the hanging ring 4 is pre-buried on the inner well wall, and the free end is hung on the hanging ring 4 by a connecting rope. The structure is simple and convenient for subsequent removal.

[0049] Furthermore, the splicing device 1 can cut the connecting rope when it moves in the circumferential direction. A cutting knife is provided on the pulling head of the splicing device 1. When the splicing device 1 moves in the forward direction along the circumference of the inner well wall, the blade of the cutting knife faces away from the connecting rope at the free end. When the splicing device 1 moves in the reverse direction along the circumference of the inner well wall, the blade of the cutting knife faces the connecting rope at the free end. After the splicing device 1 moves a complete circle along the track 2 to connect the first joining edge and the second joining edge, the pulling head of the splicing device 1 is disengaged from the first joining edge and the second joining edge under the remote control of the staff, and moves in the reverse direction along the track 2, thereby cutting the connecting rope at the free end. At this time, the first covering film 31 and the second covering film 32 are spliced ​​into a whole, and the free end of the first covering film 31 is disconnected from the inner well wall and can be folded downward under the action of gravity.

[0050] Furthermore, if Figure 1 As shown, the bottom sealing auxiliary system also includes a bundling assembly. When the covering film assembly 3 is in a sunken state, the bundling assembly is used to fold and fix the second covering film 32 on the inner well wall of the first joint edge close to the wellhead. Since the second covering film 32 is folded and fixed on the inner well wall by the bundling assembly when the covering film assembly 3 is in a sunken state, it does not affect the excavated earth and the construction equipment from the wellhead to the excavation surface.

[0051] The specific structure of the bundling assembly can be set according to actual needs, as long as it can ensure that the second covering film 32 is firmly fixed to the inner well wall and is easy to disassemble; illustratively, the staff folds the second covering film 32 into a curled state in advance, and the bundling assembly includes an electromagnet, an adsorbent and a strap, the electromagnet is arranged on the inner well wall, one end of the strap is fixed to the inner well wall, and the other end of the strap is provided with an adsorbent, the strap is against the folded second covering film 32, and the electromagnet can adsorb the adsorbent after being energized, thereby fixing the second covering film 32 to the inner well wall; when the caisson 100 sinks to the specified depth, the staff stops energizing the electromagnet, the strap falls off the electromagnet, and the second covering film 32 can be detached from the inner well wall and unfolded under the drive of the splicing device 1.

[0052] In order to further improve the quality of the bottom seal, a mud-blocking net portion 321 is provided on the second covering film 32, and the mud-blocking net portion 321 is used to filter the mud on the excavation surface; the mud-blocking net portion 321 is arranged in the central area of ​​the second covering film 32. When the first covering film 31 and the second covering film 32 are attached to the excavation surface under the action of gravity, the mud-blocking net portion 321 can filter the mud on the excavation surface and only allow water to pass through, thereby discharging the water under the covering film assembly 3, avoiding the occurrence of bulging below when pouring the bottom seal concrete, thereby ensuring the quality of the bottom seal.

[0053] This embodiment also provides a caisson bottom sealing method, using the above-mentioned caisson bottom sealing auxiliary system, including the following steps:

[0054] S1. Wrap the first covering film 31 around the inner well wall, and fix the end of the first covering film 31 away from the wellhead to the upper end of the blade foot, the upper end of the blade foot is the end of the inner well wall close to the blade foot ring, and connect the end of the first covering film 31 close to the wellhead to the inner well wall; specifically, the staff pre-embeds the fixed end of the first covering film 31 into the upper end of the blade foot of the inner well wall of the caisson 100, and a hanging ring 4 is also pre-embedded on the inner well wall. The staff hangs the free end of the first covering film 31 on the hanging ring 4 through a connecting rope, so that the first covering film 31 covers the inner well wall.

[0055] S2. Roll up the second covering film 32 and set it on the inner well wall, and install the splicing device 1 on the inner well wall; specifically, the staff folds the second covering film 32 into a rolled state, and uses a bundling assembly to fix the shielded second covering film 32 on the inner well wall above the first joint edge; then set the splicing device 1 on the track 2 of the inner well wall.

[0056] S3, excavating the soil layer to sink the caisson 100 to a specified depth; since the inner well wall is coated with the first covering film 31, the first covering film 31 can isolate the soil and the inner well wall during the sinking process of the caisson 100.

[0057] S4, connecting the first joint edge and the second joint edge to the splicing device 1 respectively, driving the splicing device 1 to move along the circumference of the inner well wall, so that the second joint edge is directly connected to the first joint edge.

[0058] Specifically, the splicing device 1 includes a driving motor, running wheels and a pulling head matching the chain teeth, the running wheels are arranged on a track 2 on the inner well wall and can move along the track 2; after the caisson 100 sinks to a specified depth, the staff connects the two ends of the pulling head to the first joining edge and the second joining edge respectively, and controls the driving motor to drive the running wheels to rotate, thereby making the splicing device 1 move along the circumference of the inner well wall, and pull the first joining edge and the second joining edge together during the movement.

[0059] S5. Remove the end of the first covering film 31 close to the wellhead, so that the covering film assembly 3 is folded to the casting state under the action of gravity. Specifically, after the splicing device 1 moves a complete circle in the circumferential direction, the first covering film 31 and the second covering film 32 are completely spliced, and then the free end of the first covering film 31 is removed from the inner well wall, and then the first covering film 31 and the second covering film 32 are folded downward under the action of gravity and respectively attached to the outer surface of the opening.

[0060] S6. Pour bottom concrete onto the casting surface.

[0061] By using the caisson bottom sealing method, the first covering film 31 is coated on the inner wall of the caisson 100, thereby preventing the caisson 100 from adhering to the inner wall during the sinking process, ensuring that the inner wall of the caisson 100 within the casting height range of the bottom sealing concrete is clean and free of mud, and the bonding quality of the bottom sealing concrete and the inner wall can be guaranteed without manual cleaning of the wall, thereby greatly improving the construction efficiency and construction safety; and because when the covering film assembly 3 is in a casting state, the first covering film 31 and the second covering film 32 can be respectively attached to the excavation surface and form a closed casting surface, the covering film assembly 3 can effectively isolate the excavated soil, thereby preventing the mud and sand on the excavation surface from being mixed into the concrete when casting the bottom sealing concrete and affecting the bottom sealing quality.

[0062] In order to improve the coating effect of the first covering film 31 on the inner well wall, so as to prevent soil from entering between the first covering film 31 and the inner well wall through the joint between the free end and the inner well wall during the sinking process of the caisson 100, step S1 also includes: brushing glue between the first covering film 31 and the inner well wall. In this embodiment, when the free end is hung on the hanging ring 4 by the connecting rope, the staff brushes glue between the inner well wall and the first covering film 31 to make the first covering film 31 better fit with the inner well wall; specifically, the adhesive force of the brushed glue or adhesive does not need to be too strong, it only needs to ensure that the first covering film 31 does not separate from the inner well wall, so as to prevent the subsequent covering film assembly 3 from being unable to be folded to the casting state under the action of gravity.

[0063] In order to enable the covering film assembly 3 to be smoothly folded downward to the casting state, after removing the end of the first covering film 31 close to the wellhead in step S5, the step also includes: placing heavy objects on the covering film assembly 3; specifically, after cutting off the connecting rope on the free end of the first covering film 31, the staff places heavy objects on the second covering film 32, so that the first covering film 31 can be smoothly folded downward with the plane where the fixed end is located as the flipping surface, and the speed of flipping the covering film assembly 3 downward is accelerated, thereby improving the construction efficiency.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Caisson bottom sealing auxiliary system, characterized in that: include: A splicing device (1), the splicing device (1) being movably arranged on the inner wall of the caisson (100) along the circumferential direction; The covering film assembly (3) comprises a first covering film (31) and a second covering film (32), wherein the first covering film (31) has a first joint edge enclosed along the circumference of the inner well wall, and the second covering film (32) has a second joint edge, the first joint edge and the second joint edge are of the same length, and the splicing device (1) can move along the circumference to connect the second joint edge to the first joint edge in a facing direction; The covering film assembly (3) has a sinking state and a casting state. When the covering film assembly (3) is in the sinking state, the first covering film (31) surrounds and covers the inner well wall, and the second covering film (32) is rolled up and arranged on the inner well wall. The covering film assembly (3) after the second joint edge is connected to the first joint edge can be folded to the casting state under the action of gravity. When the covering film assembly (3) is in the casting state, the first covering film (31) and the second covering film (32) are both attached to the excavation surface, and a closed casting surface is formed on the excavation surface.

2. The caisson bottom sealing auxiliary system according to claim 1, characterized in that: The first covering film (31) has a free end and a fixed end, the fixed end is away from the wellhead and fixedly arranged at the upper end of the blade foot, the upper end of the blade foot is the end of the inner well wall close to the blade foot ring, the free end is close to the wellhead and is detachably connected to the inner well wall, and the first joint edge is arranged at the free end.

3. The caisson bottom sealing auxiliary system according to claim 2, characterized in that: A hanging ring (4) is provided on the inner well wall, and the free end is tied to the hanging ring (4) via a connecting rope.

4. The caisson bottom sealing auxiliary system according to claim 3, characterized in that: The splicing device (1) can cut the connecting rope by moving in the circumferential direction.

5. The caisson bottom sealing auxiliary system according to claim 1, characterized in that: The bottom sealing auxiliary system also includes a tying assembly, which is used to fold and fix the second covering film (32) on the inner well wall of the first joint edge close to the wellhead when the covering film assembly (3) is in the sinking state.

6. The caisson bottom sealing auxiliary system according to claim 5, characterized in that: The bundling assembly comprises an electromagnet, an adsorbent and a strap, wherein the electromagnet is arranged on the inner well wall, one end of the strap is fixed to the inner well wall, the other end of the strap is provided with an adsorbent, the strap rests on the folded second covering film (32), and the electromagnet can adsorb the adsorbent after being energized.

7. The caisson bottom sealing auxiliary system according to claim 1, characterized in that: The second covering film (32) is provided with a mud-isolating net portion (321), and the mud-isolating net portion (321) is used to filter mud and sand on the excavation surface.

8. A method for sealing the bottom of a caisson, using the caisson bottom sealing auxiliary system as claimed in any one of claims 1 to 7, comprising the following steps: S1, wrapping the first covering film (31) around the inner well wall, and fixing the end of the first covering film (31) away from the well head to the upper end of the blade foot, the upper end of the blade foot is the end of the inner well wall close to the blade foot ring, and connecting the end of the first covering film (31) close to the well head to the inner well wall; S2, rolling up the second covering film (32) and placing it on the inner well wall, and installing the splicing device (1) on the inner well wall; S3, excavating the soil layer to sink the caisson (100) to a specified depth; S4, connecting the first joint edge and the second joint edge to the splicing device (1) respectively, and driving the splicing device (1) to move along the circumference of the inner well wall so that the second joint edge is directly connected to the first joint edge; S5, removing the end of the first covering film (31) close to the wellhead, so that the covering film assembly (3) is folded to a casting state under the action of gravity; S6. pouring bottom sealing concrete onto the casting surface.

9. The method for sealing the bottom of a caisson according to claim 8, characterized in that: Step S1 also includes: brushing glue between the first covering film (31) and the inner well wall.

10. The method for sealing the bottom of a caisson according to claim 8, characterized in that: After the end of the first covering film (31) close to the wellhead is removed in step S5, the method further comprises: A heavy object is placed onto the covering film assembly (3).

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