Externally mounted high-pressure air curtain steel casing and construction method

Abstract

The present application provides an external high-pressure air curtain steel casing, comprising two stacked steel casing bodies, the outer surfaces of the two steel casing bodies are provided with a plurality of air curtain devices, the air curtain devices comprising two side protection steel plates fixedly connected to the sides of the steel casing bodies, a plurality of adjustable fixed pipe clamps connected between the two side protection steel plates, and a sleeve valve tube connected between the plurality of adjustable fixed pipe clamps, with a plurality of air outlet holes provided on the sleeve valve tube. The present application provides an air curtain device on the outer peripheral side of the steel casing body, and can form an air curtain between the steel casing body and the soil by supplying compressed gas to the sleeve valve tube, thereby reducing the frictional resistance between the steel casing body and the soil, thereby simplifying the extraction process and improving construction efficiency; the airflow of the air curtain rises and sprays on the surface, and combined with the presence of groundwater, it actually causes the soil to liquefy, thereby significantly reducing the frictional resistance between the steel casing and the soil.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation engineering, and in particular to an externally mounted high-pressure air curtain steel casing and a construction method thereof. Background Art

[0002] In civil engineering, saturated sandy soils present numerous challenges to bored pile drilling due to their unique physical properties, such as high moisture content, low cohesion, and internal friction angle. This is particularly true when constructing foundation treatments such as vibro-compaction piles and gravel piles. The soil structure is altered, and the connections between soil particles are weakened, further exacerbating instability during the drilling process. To address these challenges, the traditional drilling method is full-casing follow-up technology. This technology uses casing throughout the entire drilling process to protect the borehole wall, preventing collapse and ensuring smooth drilling. However, while this method solves the hole collapse problem to a certain extent, it also introduces new challenges.

[0003] Due to the high frictional resistance between the casing and the surrounding soil, especially when the casing is long, the extraction process becomes extremely difficult. This not only consumes a lot of time, manpower and material resources, but also poses a potential threat to the quality of the project. If the casing is damaged or deformed during the extraction process, it will have an adverse impact on subsequent construction work. Therefore, we have made improvements to this problem and proposed an external high-pressure air curtain steel casing and its construction method. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the existing casing has a large frictional resistance between the casing and the surrounding soil, which makes the extraction process extremely difficult.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention provides an external high-pressure air curtain steel casing and a construction method to improve the above-mentioned problems.

[0006] The specific application is as follows:

[0007] An externally mounted high-pressure air curtain steel casing comprises two stacked steel casing bodies, the outer surfaces of the two steel casing bodies being provided with a plurality of air curtain devices, the air curtain devices comprising two side protection steel plates fixedly connected to the side surfaces of the steel casing bodies, a plurality of adjustable fixed pipe clamps being connected between the two side protection steel plates, and a sleeve valve tube being connected between the plurality of adjustable fixed pipe clamps, the sleeve valve tube being provided with a plurality of air outlet holes.

[0008] As the preferred technical solution of the present application, a plurality of rubber sleeves are provided on the outer surface of the sleeve valve tube, and the positions of the plurality of rubber sleeves correspond to the positions of the plurality of air vents, so that the rubber sleeves wrap the air vents.

[0009] As a preferred technical solution of the present application, a plurality of high-pressure gas buffer baffles are fixedly connected between the two side protection steel plates, and the positions of the plurality of high-pressure gas buffer baffles respectively correspond to the positions of the plurality of air outlet holes.

[0010] As a preferred technical solution of the present application, a plurality of lateral ventilation holes are provided on the two side protection steel plates, and the positions of the lateral ventilation holes correspond to the positions of the air outlet holes.

[0011] As a preferred technical solution of the present application, the air curtain device located on the lower steel casing body is connected to a sinking wedge block and a bottom protection steel plate, and the bottom protection steel plate is fixedly connected between the bottom ends of the two side protection steel plates.

[0012] As the preferred technical solution of the present application, the sinking-aiding wedge block is fixedly connected to the top of the bottom protective steel plate, and the two sides of the sinking-aiding wedge block are respectively fixedly connected to the two side protective steel plates.

[0013] As a preferred technical solution of the present application, a connecting pipe sleeve is connected between the sleeve valve tube located below and the sleeve valve tube located above.

[0014] As a preferred technical solution of the present application, flange plates are connected to the sides of the two steel casing bodies that are close to each other, and bolts and nuts are provided between the two flange plates.

[0015] A construction method for an externally mounted high-pressure air curtain steel casing, using the externally mounted high-pressure air curtain steel casing, further comprising the following steps:

[0016] 1. After positioning and verification, lay out the cross line and the outline of the surface casing, and bury the prefabricated surface steel casing to the predetermined elevation. The surface steel casing is only used as a guide structure for the external high-pressure air curtain steel casing;

[0017] Second, use a vibrating pile driver or a hydraulic press to cooperate with the mud bucket inside the tube to grab the mud and sink the steel casing body. Under normal circumstances, the first section of the steel casing body is relatively easy to sink. According to experience, the 1t vibration force generated by the vibrating pile driver overcomes the 5t friction resistance around the outer surface of the tube. If it is found that sinking is difficult, start the air compressor to send air to the sleeve valve pipe. The air outlet on the sleeve valve pipe sprays compressed air in all directions to form an air curtain, so that a layer of air curtain is generated around the outer wall of the steel casing body to destroy the partial friction resistance of the soil on the outer wall of the steel casing body. The air flow of the air curtain rises and sprays on the surface. Due to the presence of groundwater, the soil is actually liquefied, so that the water between the surface and the steel casing body is like bubbles of boiling water, so that the steel casing body can sink smoothly.

[0018] 3. During the sinking process of the steel casing, if complex strata are found on the front and affect the sinking, different means such as suction, grabbing, high-pressure water jetting or crushing by smashing machines will be adopted to solve the problem accordingly. During the continuous sinking process of the steel casing, the slag sucked out or grabbed will be blown into the slag truck. This slag will have a sedimentation process before transportation. Clean water will flow into the drainage trough of the site through the shallow water holes on the upper part of the truck body to the water collection well, and then be pumped into the steel casing body as circulating water, and the settled slag will be transported out of the site for treatment;

[0019] 4. When the main body of the steel casing sinks to the designed elevation, the air curtain is maintained. After the bottom of the hole is cleared, the steel cage and the conduit for pouring underwater concrete are lowered. When the first preparation of underwater concrete can ensure that the height of the pouring buries the conduit by 2m, the plate can be opened, and then the main body of the steel casing is gradually pulled up. If there are difficulties in pulling up, the main body of the steel casing is loosened by a jack to destroy its critical maximum friction resistance. Then, the main body of the steel casing and the conduit are pulled up at the same time by a crane or derrick. At this time, compressed air is continuously introduced into the sleeve valve pipe to maintain the air curtain to ensure that the pulling can proceed smoothly. Since the slump of underwater concrete is 18~22cm, pumped commercial concrete is used to lift the main body of the steel casing while pouring until the pile is poured.

[0020] As the preferred technical solution of this application, it also includes:

[0021] 5. After the pile top is chiseled to the required elevation of the base, pour the foundation slab concrete according to the original procedure. According to the requirements of the building code, after the pile top is exposed by excavation, conduct a completion inspection of the pile position plane displacement.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In the solution of the present application: In order to solve the problem in the prior art that a large frictional resistance is generated between the casing and the surrounding soil, making the pulling-out process extremely difficult, the present application sets an air curtain device on the outer peripheral side of the steel casing body, and forms an air curtain between the steel casing body and the soil by supplying compressed gas to the sleeve valve tube, which can reduce the frictional resistance between the steel casing body and the soil, thereby simplifying the pulling-out process and improving construction efficiency; the air flow of the air curtain rises and sprays on the surface, and combined with the presence of groundwater, it actually causes the soil to liquefy, thereby significantly reducing the frictional resistance between the steel casing and the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of the external high-pressure air curtain steel casing provided for this application;

[0025] Figure 2 A schematic diagram of the structure of the external high-pressure air curtain steel casing provided for this application;

[0026] Figure 3A schematic diagram of the structure of the air curtain device provided in this application;

[0027] Figure 4 Schematic diagram of the explosion structure of the air curtain device provided in this application.

[0028] Indicated in the figure:

[0029] 1. Steel casing body; 101. Flange plate; 2. Air curtain device; 201. Side protection steel plate; 202. Adjustable fixed pipe clamp; 203. Sleeve valve tube; 206. High-pressure gas buffer baffle; 207. Rubber sleeve; 208. Side vent; 3. Sinking aid wedge block; 4. Bottom protection steel plate; 5. Connecting pipe sleeve. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0031] As described in the background art, due to the large frictional resistance between the casing and the surrounding soil, especially when the casing is long, the pulling-out process becomes extremely difficult, which not only consumes a lot of time and manpower and material resources, but also may pose a potential threat to the quality of the project. If the casing is damaged or deformed during the pulling-out process, it will have an adverse impact on subsequent construction work.

[0032] In order to solve this technical problem, the present invention provides an externally mounted high-pressure air curtain steel casing and a construction method.

[0033] Specifically, please refer to Figures 1-4 The external high-pressure air curtain steel casing specifically includes:

[0034] Two steel casing bodies 1 are stacked together, and several air curtain devices 2 are provided on the outer surfaces of the two steel casing bodies 1. The air curtain devices 2 include two side protection steel plates 201 fixedly connected to the side surfaces of the steel casing bodies 1. Several adjustable fixed pipe clamps 202 are connected between the two side protection steel plates 201, and sleeve valve tubes 203 are connected between the several adjustable fixed pipe clamps 202. Several air outlet holes are opened on the sleeve valve tubes 203.

[0035] The present invention provides an external high-pressure air curtain steel casing and a construction method. The present application sets an air curtain device 2 on the outer peripheral side of the steel casing body 1, and forms an air curtain between the steel casing body 1 and the soil by supplying compressed gas to the sleeve valve tube 203, which can reduce the frictional resistance between the steel casing body 1 and the soil, thereby simplifying the extraction process and improving construction efficiency; the air flow of the air curtain rises and sprays on the surface, and combined with the presence of groundwater, it actually causes the soil to liquefy, thereby significantly reducing the frictional resistance between the steel casing and the soil.

[0036] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein may be combined with each other.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0039] Example 1, please refer to Figures 1-4 , an externally mounted high-pressure air curtain steel casing, comprising two steel casing main bodies 1 stacked together, the outer surfaces of the two steel casing main bodies 1 are each provided with a plurality of air curtain devices 2, the air curtain device 2 comprises two side protection steel plates 201 fixedly connected to the side surfaces of the steel casing main body 1, a plurality of adjustable fixed pipe clamps 202 are connected between the two side protection steel plates 201, and a sleeve valve tube 203 is connected between the plurality of adjustable fixed pipe clamps 202, and a plurality of air outlet holes are opened on the sleeve valve tube 203. In this application, an air curtain device 2 is provided on the outer peripheral side of the steel casing main body 1, and compressed gas is supplied to the sleeve valve tube 203 to form an air curtain between the steel casing main body 1 and the soil, which can reduce the frictional resistance between the steel casing main body 1 and the soil, thereby simplifying the extraction process and improving construction efficiency; the air flow of the air curtain rises and sprays on the surface, and combined with the presence of groundwater, it actually causes the soil to liquefy, thereby significantly reducing the frictional resistance between the steel casing and the soil.

[0040] Further, such as Figure 3-Figure 4 As shown, a plurality of rubber sleeves 207 are provided on the outer surface of the sleeve valve tube 203. The positions of the plurality of rubber sleeves 207 correspond to the positions of the plurality of air outlets, so that the rubber sleeves 207 wrap the air outlets. The setting of the rubber sleeves 207 can protect the air outlets and avoid the situation where the air outlets are blocked by debris when there is no ventilation.

[0041] Further, such as Figure 3-Figure 4As shown, a number of high-pressure gas buffer baffles 206 are fixedly connected between the two side protection steel plates 201. The positions of the several high-pressure gas buffer baffles 206 correspond to the positions of the several air outlets. The setting of the high-pressure gas buffer baffles 206 enables the high-pressure air ejected from the air outlet to be evenly distributed in multiple directions.

[0042] Further, such as Figure 3-Figure 4 As shown, a number of side vents 208 are provided on both side protection steel plates 201. The positions of the side vents 208 correspond to the positions of the air outlets. The setting of the side vents 208 can also make the high-pressure air ejected from the air outlets evenly distributed in multiple directions.

[0043] Example 2 further optimizes the external high-pressure air curtain steel casing and construction method provided in Example 1. Specifically, Figure 3 As shown, the air curtain device 2 located on the lower steel casing body 1 is connected to a sinking wedge block 3 and a bottom protection steel plate 4. The bottom protection steel plate 4 is fixedly connected between the bottom ends of the two side protection steel plates 201. The setting of the bottom protection steel plate 4 can protect the bottom end of the sleeve valve tube 203 located below, thereby reducing the wear on its bottom.

[0044] Further, such as Figure 3 As shown, the sinking-aiding wedge block 3 is fixedly connected to the top of the bottom protective steel plate 4, and the two sides of the sinking-aiding wedge block 3 are respectively fixedly connected to the two side protective steel plates 201. The setting of the sinking-aiding wedge block 3 can play a role in cutting the soil and assisting the sinking when the steel casing body 1 sinks.

[0045] Further, such as Figure 1-Figure 2 As shown, a connecting pipe sleeve 5 is connected between the sleeve valve tube 203 located below and the sleeve valve tube 203 located above. The connecting pipe sleeve 5 is used to connect the two sleeve valve tubes 203 below and above together to realize the delivery of compressed air.

[0046] Further, such as Figure 1-Figure 2 As shown, the two steel casing bodies 1 are connected to each other on one side with flange plates 101 , and bolts and nuts are provided between the two flange plates 101 , and the two flange plates 101 can be connected together by the bolts, nuts and flange plates 101 .

[0047] Example 3, a construction method of an externally mounted high-pressure air curtain steel casing, using the externally mounted high-pressure air curtain steel casing, further comprising the following steps:

[0048] 1. After positioning and verification, lay out the cross lines and the outline of the surface casing, and bury the prefabricated surface steel casing to the predetermined elevation. Generally, the top of the casing is about 10 cm above the ground. This surface steel casing is only used as a guide structure for the external high-pressure air curtain steel casing, and its inner diameter is 10~20 mm larger than the outer diameter of the external high-pressure air curtain steel casing.

[0049] Second, use a vibrating pile driver or a hydraulic press in conjunction with a bucket inside the tube to grab the mud and sink the steel casing main body 1. Under normal circumstances, the first section of the steel casing main body 1 is relatively easy to sink. According to experience, the 1t vibration force generated by the vibrating pile driver overcomes the 5t frictional resistance around the outer surface of the tube. If the groundwater level is high and water replenishment can be timely, the method of sucking mud while vibrating and sinking can be adopted, which is more effective. If it is found that sinking is difficult, the air compressor can be started to supply air to the sleeve valve pipe 203, and the air outlet on the sleeve valve pipe 203 sprays compressed air in all directions to form an air curtain, so that a layer of air curtain is generated around the outer wall of the steel casing main body 1 to destroy the partial frictional resistance of the soil to the outer wall of the steel casing main body 1. The air flow of the air curtain rises and is ejected on the surface. Due to the presence of groundwater, the soil is actually liquefied, so that the water between the ground surface and the steel casing main body 1 is like bubbles of boiling water, so that the steel casing main body 1 can sink smoothly.

[0050] 3. During the sinking process of the steel casing body 1, if a complex stratum is found on the front and affects the sinking, different means of suction, grabbing, high-pressure water jetting or smashing are adopted to solve the problem accordingly. Therefore, the means of clearing mud in the steel casing body 1 can be used freely to select the appropriate method to calmly achieve the purpose of sinking. This is also an advantage that other bored piles cannot match. During the continuous sinking process of the steel casing body 1, the slag sucked out or grabbed is blown into the slag truck. The slag has a sedimentation process before transportation, and the clean water passes through the vehicle body. The shallow water hole at the top flows into the drainage trough of the site to the water collection well, and then is pumped into the steel casing body 1 as circulating water, and the settled slag is transported out of the site for treatment. Of course, if the sucked muddy water can meet the discharge standard, it can also be allowed to flow into the sewage pipe. The water replenishment work in the steel casing body 1 can be supplemented by pumping groundwater, tap water or nearby river water to ensure that there is a certain head when sucking mud to prevent sand from turning over at the bottom of the tube, so that mud suction or reverse circulation drilling can proceed normally. The general mud suction machine pipe diameter is 150mm, which is sufficient.

[0051] 4. After the steel casing body 1 sinks to the designed elevation, the air curtain is maintained to prevent the soil from consolidating the steel casing and affecting the pulling up of the steel casing body 1. After the bottom of the hole is cleared, the steel cage and the conduit for pouring underwater concrete are lowered. There are many ways to fix the position of the steel cage, which will not be described in detail. As long as the steel cage does not float up when pouring underwater concrete, the plate can be opened when the first preparation of underwater concrete can ensure that the height of the pouring buries the conduit 2m, and then the steel casing body 1 can be gradually pulled up. If it is difficult to pull up, the steel casing body 1 can be loosened by using a jack to destroy its critical maximum friction resistance, and then the steel casing body can be pulled up at the same time by a crane or a derrick. 1 and the conduit, at this time, compressed air is continuously introduced into the sleeve valve tube 203 to maintain the air curtain and ensure that the pulling can proceed smoothly. Since the slump of underwater concrete is 18~22cm, in order to occupy less land in the city, pumped commercial concrete is used, and the steel casing body 1 is lifted while pouring until the pile is poured. This kind of pile formation not only ensures the quality of the concrete and the protective layer of the steel cage, but also the pile wall formed by the concrete squeezed into the space left by the pulling out of the steel casing body 1 is also quite rough, which correspondingly increases the friction bearing capacity. Compared with the pile wall of the same diameter formed by mud wall or the pile wall formed by sinking the steel sleeve of the pile driver, the safety factor is much greater.

[0052] Furthermore, it also includes:

[0053] 5. After the pile top is chiseled to the required elevation of the base, the foundation slab concrete is poured according to the original procedure. According to the requirements of the building code, after the pile top is exposed by excavation, the plane displacement of the pile position is inspected for completion. Dynamic tests with large or small strains are also carried out. In addition to checking the quality of the pile, its purpose should also verify its bearing capacity. The tests are all existing technologies and will not be repeated in this application.

[0054] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0055] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned specific embodiments, or to make equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the present invention specification and drawings, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. An external high-pressure air curtain steel casing, characterized in that: The invention comprises two steel casing bodies (1) stacked together, wherein the outer surfaces of the two steel casing bodies (1) are provided with a plurality of air curtain devices (2), wherein the air curtain devices (2) comprise two side protection steel plates (201) fixedly connected to the sides of the steel casing bodies (1), a plurality of adjustable fixed pipe clamps (202) are connected between the two side protection steel plates (201), and a sleeve valve tube (203) is connected between the plurality of adjustable fixed pipe clamps (202), and a plurality of air outlet holes are provided on the sleeve valve tube (203); A plurality of high-pressure gas buffer baffles (206) are fixedly connected between the two side protection steel plates (201), and the positions of the plurality of high-pressure gas buffer baffles (206) respectively correspond to the positions of the plurality of gas outlet holes; A plurality of lateral ventilation holes (208) are provided on both side protection steel plates (201), and the positions of the lateral ventilation holes (208) correspond to the positions of the air outlet holes; A connecting pipe sleeve (5) is connected between the sleeve valve pipe (203) located below and the sleeve valve pipe (203) located above.

2. The external high-pressure air curtain steel casing according to claim 1 is characterized in that: A plurality of rubber sleeves (207) are sleeved on the outer surface of the sleeve valve tube (203), and the positions of the plurality of rubber sleeves (207) respectively correspond to the positions of the plurality of air outlet holes, so that the rubber sleeves (207) cover the air outlet holes.

3. The external high-pressure air curtain steel casing according to claim 2 is characterized in that: The air curtain device (2) located on the lower steel casing body (1) is connected to a sinking aid wedge block (3) and a bottom end protection steel plate (4), and the bottom end protection steel plate (4) is fixedly connected between the bottom ends of the two side protection steel plates (201).

4. The external high-pressure air curtain steel casing according to claim 3 is characterized in that: The sinking-aiding wedge block (3) is fixedly connected to the top of the bottom protective steel plate (4), and both sides of the sinking-aiding wedge block (3) are respectively fixedly connected to the two side protective steel plates (201).

5. The externally mounted high-pressure air curtain steel casing according to claim 4 is characterized in that: The two steel casing bodies (1) are connected to each other on one side thereof, and flange plates (101) are connected thereto, and bolts and nuts are provided between the two flange plates (101).

6. A construction method for an externally mounted high-pressure air curtain steel casing, using the externally mounted high-pressure air curtain steel casing according to claim 5, characterized in that: The following steps are also included:

1. After positioning and verification, lay out the cross line and the outline of the surface casing, and bury the prefabricated surface steel casing to the predetermined elevation. The surface steel casing is only used as a guide structure for the external high-pressure air curtain steel casing; Second, use a vibrating pile driver or a hydraulic press in conjunction with a mud bucket inside the tube to grab the mud and sink the steel casing body (1). Under normal circumstances, the first section of the steel casing body (1) is relatively easy to sink. According to experience, the 1t vibration force generated by the vibrating pile driver overcomes the 5t friction resistance around the outer surface of the tube. If it is found that sinking is difficult, start the air compressor to send air to the sleeve valve pipe (203). The air outlet on the sleeve valve pipe (203) sprays compressed air in all directions to form an air curtain, so that a layer of air curtain is generated around the outer wall of the steel casing body (1) to destroy the friction resistance of the soil on the outer wall of the steel casing body (1). The air flow of the air curtain rises and sprays on the surface. Due to the presence of groundwater, the soil is actually liquefied, so that the water between the surface and the steel casing body (1) is like bubbles of boiling water, so that the steel casing body (1) can sink smoothly; 3. During the sinking process of the steel casing body (1), if a complex stratum is found on the front side and affects the sinking, different means such as suction, grabbing, high-pressure water jetting or crushing by a smashing machine are adopted to solve the problem accordingly. During the continuous sinking process of the steel casing body (1), the slag soil sucked out or grabbed is blown into the slag truck. The slag soil has a sedimentation process before being transported. Clean water flows into the drainage trough of the site through the shallow water holes on the upper part of the truck body to the water collection well, and is then pumped into the steel casing body (1) as circulating water, and the settled slag soil is transported out of the construction site for disposal; 4. When the steel casing body (1) sinks to the design elevation, the air curtain is maintained. After the bottom of the hole is cleared, the steel cage and the conduit for pouring underwater concrete are lowered. When the first preparation of underwater concrete can ensure that the pouring height buries the conduit by 2m, the plate can be opened, and then the steel casing body (1) is gradually pulled up. If there is difficulty in pulling up, the steel casing body (1) is loosened by a jack to destroy its critical maximum friction resistance. Then, the steel casing body (1) and the conduit are pulled up at the same time by a crane or a derrick. At this time, compressed air is continuously introduced into the sleeve valve pipe (203) to maintain the air curtain and ensure that the pulling can proceed smoothly. Since the slump of underwater concrete is 18~22cm, commercial concrete is pumped and the steel casing body (1) is lifted while pouring until the pile is poured.

7. The construction method of an externally mounted high-pressure air curtain steel casing according to claim 6, characterized in that: Also includes:

5. After the pile top is chiseled to the required elevation of the base, pour the foundation slab concrete according to the original procedure. According to the requirements of the building code, after the pile top is exposed by excavation, conduct a completion inspection of the pile position plane displacement.

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