CN115030206A

CN115030206A - Open caisson construction method

Info

Publication number: CN115030206A
Application number: CN202210724404.XA
Authority: CN
Inventors: 李波; 陈长; 刘嘉仪; 郭睿
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2022-06-24
Filing date: 2022-06-24
Publication date: 2022-09-09

Abstract

The invention discloses a sunk well construction method, which comprises the following steps: firstly, prefabricating a sunk well at a well mouth position, and putting a supporting cylinder in the prefabricated sunk well; secondly, excavating and removing an annular soil body between the open caisson and the supporting barrel, ensuring that the open caisson and the supporting barrel sink synchronously in the soil body excavating and removing process, and performing primary bottom sealing on an annular area between the open caisson and the supporting barrel after the open caisson and the supporting barrel sink synchronously to a specified depth; then, excavating the soil body in the supporting cylinder until reaching the specified depth; and finally, removing the supporting cylinder and taking out, and carrying out secondary bottom sealing on the whole area of the bottom of the open caisson. The method is divided into two sections for taking soil, the soil taking in the first section annular area realizes the sinking of the open caisson, and the soil body in the supporting cylinder maintains the weight for the bottom of the open caisson in the process, so that the problem of bottom soil gushing is solved. Along with the reduction of the soil gushing amount at the bottom of the well, on one hand, the problem of surrounding surface subsidence is relieved, and the damage of foundation settlement to the surrounding environment is reduced; on the other hand, the excavation amount of the soil body is reduced, and the construction efficiency is improved.

Description

Open caisson construction method

Technical Field

The invention relates to the technical field of open caisson construction, in particular to an open caisson construction method.

Background

The foundation method for open caisson construction is that firstly, a cylindrical structure of the open caisson is constructed on the ground, then, the open caisson is dug in the well by machinery and manpower, so that the open caisson is sunk to a designed elevation by overcoming the frictional resistance of the well wall, the counter force of the blade foot and the buoyancy of water under the enclosing action of the well wall and other auxiliary measures, and then, the bottom is closed, and an internal structure is constructed. In the excavation process, because the soil body is dug away in the well, there is pressure differential in the inside and outside soil body of well under the dead weight effect, and the outside soil body of well extrudees inwards, presents the phenomenon of surging in to the well, causes near soil body settlement on a large scale, brings the potential safety hazard for the surrounding environment, and the sand that constantly surges in the well also causes the trouble for the construction. The following method is commonly adopted in the related technology to solve the problem of bottom soil inrush in the open caisson chamber:

(1) solidifying soft soil foundation method: the reinforcement measure of the soft soil foundation in the open caisson chamber is mainly grouting reinforcement, and the silt soil body is reinforced by injecting high-pressure cement slurry into silt soil so as to prevent the soil body from upwelling. (2) A foundation pit enclosure method: the pile bodies such as steel plate piles, channel steel and the like are driven into the outer wall of the well chamber to exceed the cutting edge for a certain depth, so that a reliable curtain is formed to reduce the surrounding soil pressure, and the soil mass in the well chamber is prevented from upwelling. In the method, the foundation pit enclosure still causes excessive sinking of the peripheral soil body due to the fact that the enclosure pile is long, construction difficulty is high, cost is high, and disturbance on the soil body around the well body is excessive. (3) Wet bottom sealing construction method: the open caisson wet bottom sealing construction is that a submersible is submerged by a diver to set up a pouring platform after water is stored and back-pressed to sludge by utilizing the dead weight pressure of water, and underwater concrete pouring is carried out through a guide pipe. The method has high danger, and the concrete poured and sunk through the guide pipe is easy to be polluted by silt and cannot generate strength, so the reliability is low.

The method solves the problems of long construction duration, high cost and poor safety existing in the process of bottom soil burst in the open caisson chamber, mostly ignores the influence on the surrounding environment in the construction process, and is only limited to the condition of small size even considering the influence on adjacent buildings.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a construction method of an open caisson, which has small influence on the surrounding soil environment and reduces the problem of soil inrush at the bottom of a well chamber of the open caisson.

The embodiment of the invention provides a sunk well construction method, which comprises the following steps:

prefabricating a sunk well at a well mouth position, and putting a supporting cylinder in the prefabricated sunk well;

excavating an annular soil body between the open caisson and the supporting barrel, and ensuring that the open caisson and the supporting barrel sink synchronously in the soil body excavating process;

when the open caisson and the supporting cylinder are synchronously sunk to a specified depth, carrying out primary bottom sealing on an annular area between the open caisson and the supporting cylinder, wherein the specified depth is the designed excavation depth of the open caisson;

excavating soil in the supporting cylinder until reaching the specified depth;

and disassembling and taking out the supporting cylinder, and performing secondary bottom sealing on the whole area of the bottom of the open caisson.

According to the embodiment of the invention, the method has the following beneficial effects: the open caisson construction method provided by the application is characterized in that the open caisson is prefabricated at the position of a well mouth, and a supporting cylinder is placed in the prefabricated open caisson; firstly, excavating an annular soil body between an open caisson and a supporting barrel, ensuring that the open caisson and the supporting barrel sink synchronously in the soil body excavating process, and performing primary bottom sealing on an annular area between the open caisson and the supporting barrel after the open caisson and the supporting barrel sink synchronously to a specified depth; secondly, excavating the soil body in the supporting cylinder until reaching the specified depth; then the supporting cylinder is dismantled and taken out; and finally, carrying out secondary bottom sealing on the whole area of the bottom of the open caisson. According to the method, the traditional one-time open caisson construction is improved into two stages for soil taking, soil in an annular area at the first stage is excavated to realize open caisson sinking, and in the open caisson sinking process, the soil in a support cylinder can maintain enough weight on the bottom of a well, so that the problem of soil gushing at the bottom of a well chamber is effectively reduced; along with the reduction of the soil burst amount at the bottom of the well, on one hand, the problem of the collapse of the surrounding ground surface is relieved, the safety of important existing facilities near the open caisson is ensured, and the damage of foundation settlement to the surrounding environment is reduced; on the other hand, the excavation amount of the soil body is reduced, and the construction efficiency is improved.

According to some embodiments of the invention, a plurality of partition plates are arranged in an annular area between the open caisson and the support cylinder to connect the open caisson and the support cylinder into a whole so as to ensure that the open caisson and the support cylinder sink synchronously.

According to some embodiments of the invention, the open caisson is prefabricated in a plurality of sections, a first section of the open caisson is prefabricated at the position of a wellhead, a support cylinder is placed in the prefabricated first section of the open caisson, an annular soil body between the first section of the open caisson and the support cylinder is dug out, and the first section of the open caisson and the support cylinder are ensured to sink synchronously in the digging out process;

after the first section of open caisson and the supporting cylinder are synchronously sunk for a first depth, a second section of open caisson is prefabricated on the upper portion of the first section of open caisson, and the second section of open caisson and the first section of open caisson are arranged in an aligned mode;

continuously excavating the annular soil body between the second section of the open caisson and the support barrel until the second section of the open caisson and the support barrel synchronously sink to a second depth;

and repeating the operations in sequence, prefabricating a plurality of sections of open caisson arranged in an aligned mode and sinking until the first section of open caisson sinks to a specified depth.

According to some embodiments of the present invention, the height value of the first section of the open caisson is greater than the first depth value, the height value of the second section of the open caisson is greater than the second depth value, and so on, the height value of each section of the open caisson is greater than the depth value of the corresponding sinking.

According to some embodiments of the present invention, the supporting cylinder is manufactured and assembled in several sections, first placing a first section of supporting cylinder in a prefabricated first section of caisson, after the first section of caisson and the first section of supporting cylinder are synchronously sunk to a first depth, prefabricating a second section of caisson on the first section of caisson, and arranging the second section of caisson in alignment with the first section of caisson, and assembling a second section of supporting cylinder on the first section of supporting cylinder, and arranging the second section of supporting cylinder in alignment with the first section of supporting cylinder, wherein,

the height of the first section of supporting cylinder is the same as that of the first section of open caisson, and the height of the second section of supporting cylinder is the same as that of the second section of open caisson;

repeating the above operations in sequence, after prefabricating the open caisson every time, correspondingly assembling the supporting cylinders with the same height as the prefabricated open caisson in the prefabricated open caisson.

According to some embodiments of the invention, the process of prefabricating the open caisson at the wellhead location and placing the support cylinder in the open caisson is embodied as follows: and excavating and leveling a field at the position of a well mouth, erecting and pouring a formwork on the leveled ground, forming an open caisson after concrete is poured and molded, and placing a support cylinder at the central position of the open caisson after the open caisson is prefabricated.

According to some embodiments of the invention, the support cylinder is made of metal, and the method of assembly between the sections of support cylinder is welding.

According to some embodiments of the invention, a plurality of suction dredge machines are adopted for simultaneous construction in the process of excavating the soil body in the supporting cylinder until the soil body reaches the specified depth, so that the large-area soil body in the supporting cylinder can be quickly taken out.

According to some embodiments of the invention, the first and second back covers are both processed using concrete-sprayed back covers.

According to some embodiments of the invention, the cross-sectional shape of the support cylinder is adjusted according to the design shape of the open caisson.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic view of a state after a first section of open caisson is prefabricated at a wellhead and is placed in a first section of supporting cylinder in the construction process of the open caisson construction method provided by the embodiment of the application;

fig. 2 is a schematic view of a state after an open caisson is sunk to a specified depth in a construction process of the open caisson construction method provided by the embodiment of the application;

fig. 3 is a schematic state diagram after a first bottom sealing is finished in a construction process of the open caisson construction method provided by the embodiment of the application;

fig. 4 is a schematic view of a soil excavation process inside a support cylinder in the construction process of the open caisson construction method provided by the embodiment of the application;

fig. 5 is a schematic state diagram after the second bottom sealing is finished in the construction process of the open caisson construction method provided in the embodiment of the present application;

fig. 6 is a schematic plan view of a caisson in a construction process according to the caisson construction method provided by the embodiment of the present application.

Reference numerals: the open caisson comprises an open caisson 100, a first section of open caisson 110, a second section of open caisson 120, a supporting cylinder 200, a first section of supporting cylinder 210, a second section of supporting cylinder 220, a first bottom sealing 300, a second bottom sealing 400, a partition 500 and a soil body 600.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, a plurality of means is one or more, a plurality of means is two or more, and greater than, less than, more than, etc. are understood as excluding the essential numbers, and greater than, less than, etc. are understood as including the essential numbers. The terms first, second and the like in the description and in the claims, and the drawings described above, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, unless explicitly defined otherwise, terms such as set, mounted, connected, etc., should be interpreted broadly, such as a fixed connection or a movable connection, and may be a detachable connection or a non-detachable connection, or an integral connection; either directly or indirectly through intervening media, or through both elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The open caisson is a well cylindrical structure, and is a foundation for bridge abutment or other structures by digging soil in the open caisson, overcoming the frictional resistance of the well wall by means of the self gravity, sinking to a designed elevation, and then sealing the bottom by concrete. The open caisson construction is essentially a construction process of sinking a structure cast in advance on the ground into the ground to a certain depth by digging earth to form an underground structure. In the excavation process, because the soil body is dug away in the well, there is pressure differential in the inside and outside soil body of well under the dead weight effect, leads to the outside soil body of well to inwards extrude, presents the phenomenon of surging in to the well, causes near soil body settlement on a large scale, brings the potential safety hazard for the surrounding environment, and the sand that constantly has gushed in the well also causes the trouble for the construction.

In order to solve the problems, the application provides a sunk well construction method which is suitable for sunk well construction in a muddy soft soil foundation or a high-water-level sandy soil layer and relieves the problem of soil gushing at the bottom of a sunk well 100 in the construction process, so that the influence on the surrounding environment and adjacent buildings is reduced, and the method specifically comprises the following steps: firstly, prefabricating the open caisson 100 at a wellhead position, and placing a support cylinder 200 in the prefabricated open caisson 100; secondly, excavating the annular soil body 600 between the open caisson 100 and the support barrel 200, ensuring that the open caisson 100 and the support barrel 200 sink synchronously in the excavating process of the soil body 600, and performing primary bottom sealing 300 on the annular area between the open caisson 100 and the support barrel 200 after the open caisson 100 and the support barrel 200 sink synchronously to a specified depth; then, excavating the soil body 600 in the supporting cylinder 200 until reaching the designated depth; finally, the supporting cylinder 200 is disassembled and taken out, and the whole area of the bottom of the open caisson 100 is subjected to secondary bottom sealing 400.

Note that the specified depth refers to a designed excavation depth of the open caisson 100. Referring to fig. 1, the process of prefabricating the open caisson 100 at the wellhead position and placing the support cylinder 200 in the open caisson 100 is specifically as follows: and excavating and leveling a field at the position of a well mouth, erecting and pouring a formwork on the leveled ground, forming the open caisson 100 after concrete is poured and molded, and placing the supporting cylinder 200 at the central position of the open caisson 100 after the open caisson 100 is prefabricated. Compared with the traditional open caisson construction operation, the method has the advantages that the disposable soil body excavation is changed into the two-stage soil body excavation in the mode that the supporting barrel 200 is arranged inside the open caisson 100. The object excavated in the first stage is a soil body 600 in an annular area between the open caisson 100 and the supporting cylinder 200, and the first stage is to sink the wall of the open caisson 100 and ensure that the open caisson 100 and the supporting cylinder 200 sink synchronously in the excavation process, so that the open caisson 100 or the supporting cylinder 200 is prevented from deviating to a large extent and inconvenience is brought to later construction.

In the first stage excavation process, the open caisson 100 and the supporting cylinder 200 sink synchronously under the action of self gravity, the soil body 600 in the supporting cylinder 200 is kept still, and the soil body 600 can provide enough weight for the bottom surface of the open caisson 100 under the action of gravity, so that the problem that a large amount of soil gushes into a well chamber is solved. Along with the rapid reduction of the soil gushing amount at the bottom of the open caisson 100, on one hand, the soil excavation amount can be reduced, and the construction efficiency is improved; on the other hand, the surface around the construction point can be prevented from collapsing, the damage of foundation settlement to the surrounding environment is reduced, and the safety of important existing facilities near the open caisson 100 is better guaranteed. Further, in the sinking process of the open caisson 100, the supporting cylinder 200 also plays a role in maintaining the stability of the internal central soil body 600, and the smooth excavation of the soil body 600 in the annular area is guaranteed.

Further, the present application connects the open caisson 100 and the support cylinder 200 as one body with a plurality of spacers 500 to ensure synchronous sinking between the open caisson 100 and the support cylinder 200. Referring to fig. 6, as an example, in an embodiment of the present invention, 6 partition boards 500 are distributed in a circumferential array in an annular region between the open caisson 100 and the support caisson 200, and both ends of each partition board 500 are respectively connected to the open caisson 100 and the support caisson 200, so that the open caisson 100 and the support caisson 200 are integrated, thereby ensuring that they are synchronously sunk during the excavation process of the first stage. In other embodiments, the number of the partition plates 500 may be other values, and the distribution mode may also be designed in other forms, so as to ensure that the partition plates 500 connect the caisson 100 and the support cylinder 200 as a synchronously movable whole, which is not further limited herein.

It should be noted that, the supporting cylinder 200 is made of metal, and the metal has a certain strength, and is convenient for the later-stage second-stage soil body 600 to be dismantled after excavation is finished. For example, in an embodiment of the present application, the supporting cylinder 200 is made of a welded steel plate, and besides, other metal materials such as copper, aluminum, etc. may also be used, which is not illustrated herein. Further, the partition plate 500 may also be made of metal, such as steel plate, copper plate, etc., and the partition plate 500 and the support cylinder 200 may be connected by welding, which is not limited in this application.

Along with the first stage excavation, the open caisson 100 and the support cylinder 200 keep synchronously sinking until the open caisson sinks to a specified depth and then stops sinking, and then the annular area between the open caisson 100 and the support cylinder 200 is subjected to first bottom sealing 300. Wherein the first back cover 300 is a concrete sprayed back cover. And after the first bottom sealing 300 is finished, performing second-stage excavation on the soil body 600 inside the supporting cylinder 200. It should be noted that, in the second stage excavation process, a plurality of suction dredge machines are used for simultaneous construction, so that the large-area soil body 600 inside the supporting cylinder 200 can be quickly taken out, the construction period can be controlled on one hand, and the problem of soil gushing at the bottom of the open caisson 100 can be further reduced on the other hand.

And after the soil body 600 in the supporting cylinder 200 is excavated to a specified depth, stopping the second-stage excavation, disassembling the supporting cylinder 200 and taking out the supporting cylinder from the open caisson 100, and finally performing second bottom sealing 400 on the whole bottom area of the open caisson 100. Similar to the first back cover 300, the second back cover 400 also uses a concrete-sprayed back cover. The excavation of the soil body 600 in the well chamber of the open caisson 100 is divided into two stages, so that the difficulty of construction of the open caisson 100 is reduced on one hand, and the problem that the soil body 600 around the open caisson 600 sinks due to the problem of well bottom soil inrush is solved on the other hand.

Further, referring to fig. 1 to 5, in order to facilitate the excavation of the soil body 600 in the first stage of the annular region, in an embodiment of the present application, the open caisson 100 is divided into a plurality of sections for prefabrication. Firstly, referring to fig. 1, a first section of open caisson 110 is prefabricated at a wellhead position, a support cylinder 200 is placed in the prefabricated first section of open caisson 110, an annular soil body 600 between the first section of open caisson 110 and the support cylinder 200 is excavated, and the first section of open caisson 110 and the support cylinder 200 are ensured to sink synchronously along with the excavation of the annular soil body 600. After the first-stage caisson 110 and the support cylinder 200 are synchronously sunk to the first depth, the second-stage caisson 120 is prefabricated at the upper part of the first-stage caisson 110, and the second-stage caisson 120 is aligned with the first-stage caisson 110.

It should be noted that the height value of the first open caisson 110 is greater than the first depth value, that is, the first open caisson 110 is not completely submerged into the ground surface, but a small portion of the first open caisson 110 is left on the upper portion of the ground surface, which facilitates the subsequent prefabrication of the second open caisson 120 on the first open caisson 110. Further, the process of prefabricating the second section of open caisson 120 on the first section of open caisson 110 is to erect formwork and pour above the first section of open caisson 110, form the second section of open caisson 120 after pouring is completed, and ensure that the second section of open caisson 120 is aligned with the first section of open caisson 110.

After the prefabrication of the second section of the open caisson 120 is completed, continuously excavating the annular soil body 600 between the second section of the open caisson 120 and the support barrel 200 until the second section of the open caisson 120 and the support barrel 200 sink synchronously to a second depth; similarly, the height value of the second section of caisson 120 is greater than the second depth value, that is, the second section of caisson 120 is not completely sunk into the ground surface, but a small portion of caisson is left on the upper portion of the ground surface, which facilitates the subsequent prefabrication of a third section of caisson (not shown) on the second section of caisson 120. The prefabrication process of the third section of the open caisson is the same as that of the second section of the open caisson 120, and the third section of the open caisson is also aligned with the first section of the open caisson 110 and the second section of the open caisson 120.

Referring to fig. 2, the above operations are sequentially repeated, that is, a plurality of sections of the open caisson 100 are prefabricated and sunk, wherein the height value of each section of the open caisson 100 is greater than the depth value of the corresponding sinking, until the first section of the open caisson 110 is sunk to a designated depth, the complete excavation of the soil in the annular area is completed. And subsequently, referring to the open caisson construction process with the open caisson 100 as a whole, performing subsequent construction operations such as excavation of the soil body 600 inside the first bottom sealing 300 and the second stage of the supporting cylinder 200, dismantling of the supporting cylinder 200, and second bottom sealing 400. The open caisson 100 is prefabricated in sections, so that on one hand, pouring and forming of each open caisson section are facilitated, and on the other hand, excavation of soil bodies 600 in each annular area section is facilitated.

Similarly, in one embodiment of the present application, the support cartridge 200 is fabricated and assembled in several sections to facilitate the fabrication and transportation of the support cartridge 200. First, a first section of support cylinder 210 is placed in a prefabricated first section of open caisson 110, after the first section of open caisson 110 and the first section of support cylinder 210 sink synchronously to a first depth, a second section of open caisson 120 is prefabricated on the first section of open caisson 110, so that the second section of open caisson 120 and the first section of open caisson 110 are arranged in an aligned manner, and a second section of support cylinder 220 is assembled on the first section of support cylinder 210, so that the second section of support cylinder 220 and the first section of support cylinder 210 are arranged in an aligned manner. It should be noted that the height of the first section of the support cylinder 210 is the same as the height of the first section of the caisson 110, and the height of the second section of the support cylinder 220 is the same as the height of the second section of the caisson 120. And repeating the operations in sequence, and correspondingly assembling the supporting cylinders with the same height as the prefabricated open caisson in the prefabricated open caisson after prefabricating the open caisson every time. Further, when the support cylinder 200 is made of metal, the first section of support cylinder 210 and the second section of support cylinder 220 are assembled by welding, and similarly, the support cylinders 200 are assembled by welding.

In the construction process, the open caisson 100 and the supporting cylinder 200 are prefabricated in sections in sequence, the annular soil body 600 between each section of open caisson 100 and the supporting cylinder 200 is excavated until the state shown in fig. 2, namely, the first section of open caisson 110 sinks to the designated depth, and at this time, the excavation of the soil body 600 in the first stage is finished. Next, referring to fig. 3, a first bottoming 300 is performed on the annular region between the chamber bottom caisson 100 and the support cylinder 200. Then, referring to fig. 4, the central soil body 600 inside the supporting cylinder 200 is excavated in the second stage, and a plurality of suction dredge machines are used for construction at the same time in the process, so that the central large-area columnar soil body 600 is taken out quickly. Finally, referring to fig. 5, after the support cylinder 200 and the partition 500 inside the caisson 100 are disassembled and removed, the whole area of the bottom of the caisson 100 is subjected to secondary bottom sealing 400.

It should be noted that the support cylinder 200 is located at the center of the open caisson 100 in the present application, and the cross-sectional shape of the support cylinder 200 is adjusted according to the design shape of the open caisson 100. Referring to fig. 6, in an embodiment of the present invention, the open caisson 100 has a circular cross-sectional shape, and the supporting cylinder 200 also has a circular cross-sectional shape, and the two are concentrically arranged. The support cylinder 200 is located inside the open caisson 100, and thus the diameter of the support cylinder 200 is smaller than the diameter of the open caisson 100. In other embodiments, if the cross-sectional shape of the caisson 100 is rectangular, the cross-sectional shape of the supporting cylinder 200 can be adjusted to be rectangular, and the application is not limited thereto.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims

1. The open caisson construction method is characterized by comprising the following steps:

excavating an annular soil body between the open caisson and the support barrel, and ensuring that the open caisson and the support barrel sink synchronously in the soil body excavating process;

when the open caisson and the supporting barrel synchronously sink to a specified depth, carrying out primary bottom sealing on an annular area between the open caisson and the supporting barrel, wherein the specified depth is the designed excavation depth of the open caisson;

excavating soil in the supporting cylinder until reaching the specified depth;

2. The method as claimed in claim 1, wherein a plurality of partitions are formed in the annular region between the caisson and the support casing to connect the caisson and the support casing together, thereby ensuring the caisson and the support casing to sink synchronously.

3. The open caisson construction method according to claim 2, wherein the open caisson is prefabricated in several sections, the first section of open caisson is prefabricated at the position of a wellhead, the supporting barrel is placed in the prefabricated first section of open caisson, the annular soil body between the first section of open caisson and the supporting barrel is excavated, and the first section of open caisson and the supporting barrel are ensured to be synchronously sunk in the excavation process;

after the first section of the open caisson and the supporting cylinder are synchronously sunk for a first depth, prefabricating a second section of the open caisson on the upper part of the first section of the open caisson, and aligning the second section of the open caisson with the first section of the open caisson;

4. The open caisson construction method of claim 3, wherein the height of the first section of open caisson is greater than a first depth value, the height of the second section of open caisson is greater than a second depth value, and so on, the height of each section of open caisson is greater than the depth value of the corresponding sinking.

5. The open caisson construction method of claim 3, wherein the supporting cylinders are fabricated and assembled in several sections, first placing a first section of supporting cylinder in a prefabricated first section of open caisson, after the first section of open caisson and the first section of supporting cylinder are synchronously sunk to a first depth, prefabricating a second section of open caisson on the first section of open caisson so that the second section of open caisson is aligned with the first section of open caisson, and assembling a second section of supporting cylinder on the first section of supporting cylinder so that the second section of supporting cylinder is aligned with the first section of supporting cylinder, wherein,

and repeating the operations in sequence, and correspondingly assembling the supporting cylinders with the same height as the prefabricated open caisson in the prefabricated open caisson after prefabricating the open caisson every time.

6. The open caisson construction method according to claim 1, wherein the process of prefabricating the open caisson at the wellhead position and placing the support cylinder in the open caisson comprises: and excavating and leveling the field at the position of the wellhead, pouring a vertical mold on the leveled ground, forming the open caisson after concrete is poured and molded, and placing the supporting cylinder at the central position of the open caisson after the open caisson is prefabricated.

7. The open caisson construction method of claim 5, wherein said supporting cylinder is made of metal, and the assembling method between the supporting cylinders is welding.

8. The open caisson construction method of any one of claims 1 to 5, wherein a plurality of suction dredge machines are used for simultaneous construction in the process of excavating the soil body in the supporting cylinder until the soil body reaches the designated depth, so as to realize rapid extraction of the large-area soil body in the supporting cylinder.

9. The method of claim 1, wherein the first and second bottom sealing processes use concrete injection bottom sealing.

10. The open caisson construction method of any one of claims 1 to 6, wherein the cross-sectional shape of said support cylinder is adjusted according to the design shape of said open caisson.