CN115075278A - Progressive soil taking and sinking construction system and method for underwater oversized open caisson step - Google Patents

Abstract

The invention discloses a progressive soil taking and sinking construction system for an underwater oversized open caisson step, which comprises: open caisson, multi-functional barge, borrow platform, pipeline and broken borrowing equipment, multi-functional barge is located the open caisson side, integrated water supply equipment and air feeder on the multi-functional barge, the borrowing platform set up in the open caisson top, the pipeline includes air supply pipe and delivery pipe, broken borrowing equipment set up in on the borrowing platform and including air suction dredger, double-end reamer equipment and the coaxial efflux equipment of air water, it corresponds respectively and passes through air supply pipe and delivery union coupling water supply equipment and air feeder, air suction dredger is connected with the mud pipe. The invention also discloses a construction method for progressively taking out soil and sinking the oversized open caisson step in water. In the system, all the devices and pipelines are highly integrated, so that the devices do not interfere with each other, the pipelines are regularly arranged, the method adopts step progressive soil sampling, the construction efficiency is high, and the construction safety is high.

Description

Progressive soil taking and sinking construction system and method for underwater oversized open caisson step

Technical Field

The invention relates to the technical field of open caisson construction. More particularly, the invention relates to a gradual soil taking and sinking construction system and method for an oversized open caisson step in water.

Background

The open caisson is a well cylindrical structure, and is a foundation for bridge abutment or other structures by digging soil in the well, overcoming the frictional resistance of the well wall by means of the self gravity, sinking to a designed elevation, sealing the bottom by concrete and filling the well hole. As a large-span and heavy-duty bridge becomes the main direction of bridge development, open caisson foundation application is more and more extensive.

However, the large open caisson has large plane size and deep soil-entering depth, the open caisson soil-taking and sinking construction is very complicated, especially the large open caisson soil-taking in water needs various soil-taking devices and hoisting devices and supplies power, water and gas, and soil is taken out by the soil-taking devices, conveyed to the outside of the open caisson through a soil discharge pipeline and conveyed to the shore after being processed. Traditional open caisson borrowing equipment, pipelines etc. are mixed and disorderly, and equipment operation is mutual interference, influences the efficiency of borrowing construction. The sludge discharge line is randomly arranged, the sludge and water are difficult to be collected and treated in a centralized way, and suspended matter pollution is very easy to cause to the water body. And in the large-scale open caisson construction soil taking process, the risk of sand gushing, sudden sinking and structural cracking is large, and the traditional open caisson soil taking construction method can not meet the requirements of high efficiency, safe soil taking and sinking of the large-scale open caisson.

Disclosure of Invention

The invention aims to provide a construction system and a construction method for progressively taking soil and sinking an oversized sunk well step in water.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a progressive soil borrowing and sinking construction system for an underwater oversized open caisson step, comprising: open caisson, multi-functional barge, borrow platform, pipeline and broken borrow equipment, multi-functional barge is located the open caisson side, integrated water supply equipment and air feeder on the multi-functional barge, it set up in to borrow the platform the open caisson top, the pipeline includes air supply pipe and delivery pipe, broken borrow equipment set up in it is last just to include air suction dredge, double-end reamer equipment and the coaxial efflux equipment of air water on the platform to borrow, it corresponds respectively through air supply pipe and delivery pipe are connected water supply equipment and air feeder, air suction dredge is connected with the mud pipe.

Preferably, the water supply equipment comprises a multistage centrifugal pump and a water supply main pipe, the air supply equipment comprises an air compressor, an air storage tank and an air supply main pipe, the water supply main pipe is communicated with each water supply pipe, and the air compressor is communicated with the air storage tank and then communicated with each air supply pipe through the air supply main pipe.

Preferably, the soil sampling platform comprises a track beam and a gantry crane, the track beam is arranged along the top of the open caisson, the gantry crane is arranged on the track beam, and the soil breaking and sampling equipment is mounted on the gantry crane in a hanging manner.

Preferably, the air supply pipe, the water supply pipe and the sludge discharge pipe are all steel pipes and are arranged in parallel, and the air supply pipe, the water supply pipe and the sludge discharge pipe are integrated side by side and then are arranged into a plurality of modular units which are assembled on the soil taking platform.

Preferably, still include mud-water separation system, it includes muddy water separation ship, mud barge and sets up muddy water tank, shale shaker, the sedimentation tank on the muddy water separation ship, muddy water separation ship sets up in the outside of open caisson, the mud water tank is in the symmetry sets up a pair ofly on the mud water separation ship, be provided with the shale shaker in the mud water tank in order to with muddy water vibration separation, mud water tank bottom sets up mud discharge opening intercommunication the mud barge, the intercommunication sets up between a pair of mud water tank the sedimentation tank, sedimentation tank upper portion is provided with the discharge opening, the sedimentation tank lower part also is provided with mud discharge opening, its intercommunication the mud barge.

Preferably, the multi-purpose barge is provided with a pair and is located at both ends of a diagonal line of the open caisson, respectively.

Preferably, the mud-water separation system is symmetrically arranged in a pair along two sides of the open caisson.

The invention also provides a construction method for progressively taking out soil and sinking the oversized open caisson step in water, which comprises the following steps:

the method comprises the following steps: the method comprises the following steps that soil is taken in the inner ring, soil is taken in the inner ring well hole of the open caisson through an air suction dredge, soil in the outer ring well hole of the open caisson is not taken, and at the moment, the sinking amount of the open caisson is small;

step two: taking soil in the second stage, namely taking soil in the outer ring, taking soil in the outer ring of the open caisson through an air suction dredger, but keeping the soil body close to the outer blade foot part in the outer ring of the open caisson, wherein the soil taking depth of the outer ring is smaller than that of the inner ring, and the open caisson begins to sink;

step three: taking soil in the third stage, namely breaking soil in a blind area, breaking soil in the partition wall and the shear key soil taking blind area through a gas-water coaxial jet device, and enabling the mud surface at the bottom of the open caisson to form a step shape;

step four: and taking soil at the fourth stage, namely taking broken soil at the full section, simultaneously taking or breaking soil in a well hole at the inner ring of the open caisson through an air suction dredge and an air-water coaxial jet device after a mud surface at the bottom of the open caisson forms a step shape, taking soil in a well hole at the outer ring of the open caisson, and keeping the open caisson in a stable sinking state until the open caisson sinks to the preset depth.

Preferably, the depth of soil borrowing in the inner ring well hole of the open caisson in the first step is not more than 2 m.

The invention at least comprises the following beneficial effects:

(1) according to the invention, the soil taking equipment and the hoisting equipment, namely the gantry crane, are highly integrated, so that the problems of messy soil taking equipment and pipelines and mutual interference of equipment operation are solved, the concentrated collection of muddy water is realized, the sludge is discharged after separation and precipitation, the pollution of muddy water suspended matters to a water body is avoided, and the environmental protection sinking of the open caisson is realized.

(2) The invention adopts the cooperation of various soil taking processes, can realize step progressive (blind area) soil taking, adopts the gas lift soil taking process as a whole, adopts an electric reamer, a gas-water coaxial jet device and the like to destroy soil bodies and then gas lift soil taking aiming at special soil layers such as clay layers, cemented sand layers and the like and soil taking blind areas, and improves the soil taking efficiency and the soil taking depth control precision.

(3) Compared with the soil taking at the bottom of a large pot, the step progressive soil taking method strictly controls the overbreak depth of the open caisson, simultaneously reserves the soil body of the well hole part on the outer ring of the open caisson, and the outer ring part of the open caisson is always in an effective supporting state, so that the sand gushing and sudden sinking risks of the open caisson are avoided; compared with soil taking at the bottom of a small pot, the method effectively removes the soil body support of the blind area of the inner ring part of the open caisson, avoids the condition that the open caisson is difficult to sink or sinks slowly, and greatly improves the sinking speed of the open caisson. Compared with a cross groove drawing method and other fine soil taking methods, after the step type is formed, large-scale soil taking can be synchronously performed on the inner ring and part of the outer ring of the open caisson, and the soil taking efficiency is greatly improved.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a top view of the progressive soil borrowing and sinking construction system for the underwater oversized open caisson step;

FIG. 2 is a schematic view of a multi-purpose barge according to the invention;

FIG. 3 is a schematic elevation view of a soil sampling platform according to the present invention;

FIG. 4 is a schematic plan view of the soil sampling platform of the present invention;

FIG. 5 is a schematic view of the layout of the soil sampling platform pipeline according to the present invention;

FIG. 6 is a partially enlarged schematic view of the soil sampling platform according to the present invention;

FIG. 7 is a schematic view of the soil breaking and taking apparatus of the present invention;

FIG. 8 is a top view of the mud-water separation system of the present invention;

FIG. 9 is a schematic elevation view of the step-by-step soil borrowing construction method according to the present invention;

FIG. 10 is a schematic plan view of the step-by-step soil borrowing construction method according to the present invention;

FIG. 11 is a schematic illustration of the inner ring of the present invention for taking soil;

FIG. 12 is a schematic view of the outer ring of the present invention for taking soil;

FIG. 13 is a schematic illustration of inner race blind area ground breaking according to the present invention;

FIG. 14 is a schematic diagram of a full-section ground breaking method according to the present invention.

Description of reference numerals: 1, sinking a well; 2-inner circle well; 3-outer ring well; 4-taking a soil blind area; 5, an outer blade leg; 6-partition wall; 7-shear key;

10-a multifunctional barge; 11-a multistage centrifugal pump; 12-an air compressor; 13-a gas storage tank; 14-main gas supply pipe; 15-main water supply pipe;

20, a soil taking platform; 21-a gas supply pipe; 22-a water supply pipe; 23-a sludge discharge pipe; 24-constructing a cable bridge; 25-a track beam; 26, a gantry crane;

30-air suction dredge; 31-double-ended reamer apparatus; 32-gas-water coaxial jet equipment;

40-a mud-water separation vessel; 41-a mud water tank; 42-a vibrating screen; 43-a sedimentation tank; 44-a water discharge opening; 45-sludge discharge port; 50-barge.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

As shown in fig. 1 to 8, the present invention provides a progressive soil sampling and sinking construction system for an underwater oversized open caisson step, comprising: open caisson 1, multifunctional barge 10, borrow platform 20, pipeline and broken equipment of borrowing, multifunctional barge 10 is located 1 side of open caisson, integrated water supply equipment and air feeder on the multifunctional barge 10, the platform 20 of borrowing set up in 1 top of open caisson, the pipeline includes air supply pipe 21 and delivery pipe 22, broken equipment of borrowing set up in on the platform 20 of borrowing and including air suction dredger 30, double-end reamer equipment 31 and the coaxial efflux equipment 32 of vapor-water, it corresponds respectively and passes through air supply pipe 21 and delivery pipe 22 are connected water supply equipment and air feeder, air suction dredger 30 is connected with mud pipe 23.

In the above technical solution, the multifunctional barge 10 is correspondingly integrated with power supply equipment for supplying power to each equipment corresponding to sinking and soil sampling of the open caisson 1, and the pipeline also includes a power supply pipe, which is the same as the arrangement and connection of the water supply pipe 22 and the gas supply pipe 21. Traditional open caisson 1 sinks and fetches earth the construction method different with the construction method of this application, traditional construction method generally only need air suction dredge 30 can, only set up air supply pipe 21 and supply tube can, this application is in open caisson 1 fetches earth the sinking stage, distributes to different soil layers, carries out the rational configuration of equipment of fetching earth: each well hole is provided with a set of air suction dredge 30 which is used as a main soil taking device and is mainly responsible for taking soil in the vertical direction of the well hole of the open caisson 1; aiming at special soil layers such as silty clay, cemented sand layers and the like, on the basis of an air suction dredge 30, modular electric double-head reamer equipment 31 capable of being quickly disassembled and assembled is installed, every two modular electric double-head reamer equipment are fixed on one air-lift soil sampling equipment, and the clay and cemented sand layers are cut in a mechanical destruction mode; when blind area borrowing is required, the air-water coaxial jet device 32 is installed and mainly responsible for breaking the soil in the borrowing blind area 4, and the clay is cut in an air-water mixing mode by boosting high-pressure water through the high-pressure air curtain. The water supply pipe 22 and the gas supply pipe 21 required for hydraulic breaking and gas lift soil taking are supplied from the multi-function barge 10 arranged upstream and downstream of the open caisson 1 to the soil taking platform 20 on the top surface of the open caisson 1. Each soil breaking and taking device is connected with a corresponding air supply pipe 21 and a corresponding water supply pipe 22 according to requirements.

In another technical solution, as shown in fig. 2, the water supply device includes a multistage centrifugal pump 11 and a main water supply pipe 15, the air supply device includes an air compressor 12, an air storage tank 13 and a main air supply pipe 14, the main water supply pipe 15 is connected to each water supply pipe 22, and the air compressor 12 is connected to the air storage tank 13 and then connected to each air supply pipe 21 through the main air supply pipe 14. The air supply main pipe 14 and the water supply main pipe 15 are connected with an air supply pipe 21 and a water supply pipe 22 which correspond to the soil taking platform 20 on the top surface of the open caisson 1, and the multifunctional barge 10 is used for leading shore power to the top surface of the open caisson 1, supplies water and supplies air for the soil breaking and taking equipment on the top surface of the open caisson 1 through integrally arranging equipment such as an air compressor 12 and a multistage centrifugal pump 11, and effectively ensures the safety of soil taking and sinking construction of the open caisson 1.

In another technical solution, as shown in fig. 3 and 4, the soil-taking platform 20 includes a track beam 25 and a gantry crane 26, the track beam 25 is disposed along the top of the open caisson 1, the gantry crane 26 is disposed on the track beam 25, and the soil breaking and taking devices are all mounted on the gantry crane 26 in a hanging manner. The soil sampling platform 20 and the pipeline are arranged at the top of the open caisson 1, the gantry crane 26 tracks, namely the track beam 25, the gantry crane 26, the power supply/water/gas pipeline, the sludge discharge pipeline 23 and the like are arranged on the soil sampling platform 20, and the soil sampling platform is mainly used for providing a platform for soil sampling operation of the open caisson 1.

In another technical solution, as shown in fig. 5 and 6, the air supply pipe 21, the water supply pipe 22 and the sludge discharge pipe 23 are all steel pipes and are arranged side by side in parallel, and the air supply pipe 21, the water supply pipe 22 and the sludge discharge pipe 23 are integrated side by side and then arranged as a plurality of modular units, which are assembled and installed on the soil sampling platform 20.

In above-mentioned technical scheme, traditional open caisson 1 sinks and fetches earth and does not need water, consequently just also does not need water supply equipment, also need not integrated delivery pipe 22, only need air supply pipe 21 and power supply pipe can, each pipeline of traditional construction method all need a lesson alone to make the installation on fetching earth platform 20, and traditional pipeline uses is the hose moreover, and the patchcord is pulled up and is had no chap to the installation is loaded down with trivial details, and the efficiency of construction is low. The integrated module is formed by connecting pipelines on the shore to form an integrated module, and then the integrated module is directly assembled on the soil taking platform 20, so that the rapid assembly is realized, and the pipelines are not interfered with each other and are regular. The water supply pipeline and the gas supply pipeline 21 are arranged in parallel, and high-pressure water and high-pressure gas generated by the multistage centrifugal pump 11 and the air compressor 12 on the multifunctional barge 10 can be conveyed to each well hole of the open caisson 1. The mud pipe 23 can discharge all soil taken out of the well and intensively discharge the soil to the mud-water separation vessel 40. The soil taking platform 20 is integrated with an air supply pipe 21, a water supply pipe 22, a mud discharge pipe 23, a construction cable bridge 24, a track beam 25 and the like to meet the requirements of modular design and installation, the soil taking platform is installed at the top of the open caisson 1, and a gantry crane 26 is arranged on the track beam 25.

In another technical solution, as shown in fig. 8, the system further includes a mud-water separation system, which includes a mud-water separation vessel 40, a mud barge 50, and a mud water tank 41, a vibrating screen 42, and a settling pond 43 disposed on the mud separation vessel 40, wherein the mud separation vessel 40 is disposed outside the caisson 1, the mud water tank 41 is symmetrically disposed on the mud separation vessel 40, the vibrating screen 42 is disposed in the mud water tank 41 to separate mud from water in a vibrating manner, a mud discharge port 45 is disposed at the bottom of the mud water tank 41 and communicates with the mud barge 50, the settling pond 43 is disposed between a pair of mud water tanks 41, a water discharge port 44 is disposed at the upper portion of the settling pond 43, and a mud discharge port 45 is also disposed at the lower portion of the settling pond 43 and communicates with the mud barge 50.

In the technical scheme, the muddy water is directly discharged to the river by the traditional construction method, so that serious pollution is caused. The mud-water separation ship 40 mainly comprises a mud-water tank 41, a vibrating screen 42 and a sedimentation tank 43, and can separate mud and water taken out by soil taking equipment, discharge river and transport the mud to the shore. When the open caisson 1 takes out soil, the mud-water mixture discharged from each well hole is collected into the mud-water tank 41 of the mud-water separation vessel 40 through the mud pipe 23. The mud-water mixture is distributed to two vibrating screens 42 from a mud-water tank 41, the slag with the particle size of more than 1mm is separated by screening of the vibrating screens 42, and the slag is discharged to a mud barge 50 through a mud discharge port 45 arranged at the bottom of the mud-water tank 41. The mud-water mixture with the particle size smaller than 1mm is discharged into a sedimentation tank 43, after physical sedimentation, the clear water on the surface layer is discharged into the river through a water discharge opening 44, and the slag on the bottom layer is transferred into an adjacent mud barge 50 through a bottom mud discharge opening 45.

In another embodiment, as shown in fig. 1, the multi-purpose barge 10 is provided with a pair of ports respectively located at both ends of a diagonal line of the caisson 1. And the mud-water separation systems are symmetrically arranged in a pair along two sides of the open caisson 1.

The invention also provides a construction method for progressively taking out soil and sinking in water by using the oversized open caisson 1 step, as shown in fig. 9 to 14, the progressive soil taking in the open caisson 1 step can simultaneously take out soil from the inner and outer well bores on the premise of keeping part of soil mass of the outer well bore 3, meanwhile, the support of the soil mass in the soil taking blind zone 4 of the open caisson 1 is removed by using blind zone soil breaking equipment, and the safe, controllable and stable sinking of the open caisson 1 can be realized on the premise of ensuring the soil taking and sinking effects of the open caisson 1, and the construction method specifically comprises the following steps:

the method comprises the following steps: in the first stage, soil is taken in an inner ring, as shown in fig. 11, soil is taken in an inner ring well hole 2 of the open caisson 1 through an air suction dredge 30, soil in an outer ring well hole 3 of the open caisson 1 is not taken, the soil taking depth is determined according to calculation, the soil taking depth is generally not more than 2m (specifically determined according to calculation), and at the moment, the open caisson 1 has small sinking amount under the supporting action of the soil of the outer well wall and the inner partition wall 6;

step two: taking soil at the second stage, namely taking soil at the outer ring, as shown in fig. 12, taking soil in the outer ring well hole 3 of the open caisson 1 through an air suction dredge 30, but keeping part of soil body close to the outer cutting edge foot 5 in the outer ring well hole 3 of the open caisson 1, wherein the soil taking depth at the outer ring is smaller than that at the inner ring; the width and the depth of the step are comprehensively determined according to the state of the open caisson 1, geological conditions and the like, and the open caisson 1 begins to sink at the moment;

step three: in the third stage, taking soil, namely breaking soil in a blind area, as shown in fig. 13, breaking soil in the soil taking blind area 4 of the partition wall 6 and the shear key 7 through a gas-water coaxial jet device 32 in a blind mode, so that the mud surface at the bottom of the open caisson 1 forms a step shape;

step four: and taking soil at the fourth stage, namely taking broken soil from the full section, as shown in fig. 14, after the bottom mud surface of the open caisson 1 is stepped, taking or breaking soil in the inner ring well bore 2 of the open caisson 1 through an air suction dredge 30 and a gas-water coaxial jet device 32, taking soil in the outer ring well bore 3 of the open caisson 1, and keeping the open caisson 1 in a stable sinking state until the open caisson 1 sinks to the preset depth.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims (9)

1. The utility model provides an aquatic super large open caisson step progressive borrowing and sinking construction system which characterized in that includes: open caisson, multi-functional barge, borrow platform, pipeline and broken borrow equipment, multi-functional barge is located the open caisson side, integrated water supply equipment and air feeder on the multi-functional barge, it set up in to borrow the platform the open caisson top, the pipeline includes air supply pipe and delivery pipe, broken borrow equipment set up in it is last just to include air suction dredge, double-end reamer equipment and the coaxial efflux equipment of air water on the platform to borrow, it corresponds respectively through air supply pipe and delivery pipe are connected water supply equipment and air feeder, air suction dredge is connected with the mud pipe.

2. The progressive soil sampling and sinking construction system for the underwater oversized open caisson step as claimed in claim 1, wherein the water supply equipment comprises a multistage centrifugal pump and a main water supply pipe, the air supply equipment comprises an air compressor, an air storage tank and a main air supply pipe, the main water supply pipe is communicated with each water supply pipe, and the air compressor is communicated with the air storage tank and then communicated with each air supply pipe through the main air supply pipe.

3. The progressive soil-taking and sinking construction system for the underwater oversized open caisson step as claimed in claim 1, wherein the soil-taking platform comprises a track beam and a gantry crane, the track beam is arranged along the top of the open caisson, the gantry crane is arranged on the track beam, and the soil breaking and taking equipment is mounted on the gantry crane in a hanging manner.

4. The progressive soil borrowing and sinking construction system for the underwater oversized open caisson step as claimed in claim 1, wherein the air supply pipe, the water supply pipe and the mud discharging pipe are all steel pipes and are arranged in parallel side by side, and the air supply pipe, the water supply pipe and the mud discharging pipe are integrated side by side and then are arranged into a plurality of modular units which are assembled and installed on the soil borrowing platform.

5. The progressive soil taking and sinking construction system for the underwater oversized caisson step as claimed in claim 1, further comprising a mud-water separation system, wherein the mud-water separation system comprises a mud-water separation boat, a mud barge, and a mud water tank, a vibrating screen and a sedimentation tank which are arranged on the mud-water separation boat, the mud water tank is symmetrically arranged on the mud-water separation boat, the vibrating screen is arranged in the mud water tank to separate mud from water in a vibrating manner, a mud discharge port is arranged at the bottom of the mud water tank and communicated with the mud barge, the sedimentation tank is arranged between the mud water tank and the sedimentation tank in a communicating manner, a water discharge port is arranged at the upper part of the sedimentation tank, and a mud discharge port is also arranged at the lower part of the sedimentation tank and communicated with the mud barge.

6. The progressive soil-taking sinking construction system for extra-large open caisson step in water of claim 1, wherein said multi-function barge is provided with a pair and located at both ends of diagonal line of said open caisson.

7. The progressive soil taking and sinking construction system for the underwater oversized open caisson step as claimed in claim 5, wherein a pair of mud-water separation systems is symmetrically arranged along two sides of the open caisson.

8. The progressive soil borrowing and sinking construction method for the underwater oversized open caisson step as claimed in any one of claims 1 to 7, characterized by comprising the following steps:

the method comprises the following steps: the method comprises the following steps that soil is taken in the inner ring, soil is taken in the inner ring well hole of the open caisson through an air suction dredge, soil in the outer ring well hole of the open caisson is not taken, and at the moment, the sinking amount of the open caisson is small;

step two: taking soil in the second stage, namely taking soil in the outer ring, taking soil in the outer ring of the open caisson through an air suction dredger, but keeping the soil body close to the outer blade foot part in the outer ring of the open caisson, wherein the soil taking depth of the outer ring is smaller than that of the inner ring, and the open caisson begins to sink;

step three: taking soil in the third stage, namely breaking soil in a blind area, breaking soil in the partition wall and the shear key soil taking blind area through a gas-water coaxial jet device, and enabling the mud surface at the bottom of the open caisson to form a step shape;

step four: and taking soil at the fourth stage, namely taking broken soil at the full section, simultaneously taking or breaking soil in a well hole at the inner ring of the open caisson through an air suction dredge and an air-water coaxial jet device after a mud surface at the bottom of the open caisson forms a step shape, taking soil in a well hole at the outer ring of the open caisson, and keeping the open caisson in a stable sinking state until the open caisson sinks to the preset depth.

9. The progressive soil-taking sinking construction method for the extra-large open caisson step in water as claimed in claim 8, wherein in the first step, the depth of taking soil in the inner ring well bore of the open caisson is not more than 2 m.

Images