Process for removing existing cast-in-situ bored pile foundation in small space and application of process

Abstract

The invention discloses a process for removing a pile foundation of an existing cast-in-situ bored pile in a small space, which is characterized in that the pile foundation of the existing cast-in-situ bored pile is sectionally twisted off by matching a full-rotation sleeve with an auxiliary part within a limited height range, and then broken piles / fragments are recycled until the whole pile foundation is removed; segmented twist-off is completed in a sound insulation space formed by the sound insulation barrier, and noise generated in the segmented twist-off process is lower than 75 db. The removing technology is mainly applied to the construction environment with the small external space and the high silence requirement for disturbing residents, and then the pile foundation can be thoroughly removed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of removal of existing pile foundation, in particular to a process for removing existing bored pile foundation in a small space and application thereof. BACKGROUND

[0002] With the further development of urban construction, the space of existing projects is greatly limited, especially with too many buildings, such as in some projects, the ground buildings have been demolished, but the pile foundation has not been removed, and at the same time, in Singapore and other regions, the requirements for construction noise are relatively high, and the construction requirements need to be fully considered. SUMMARY

[0003] The purpose of the present application is to provide a process for removing existing bored pile foundation in a small space to ensure the smooth development of subsequent wall construction.

[0004] To achieve the above purpose, the present application is realized by the following technical scheme.

[0005] The process for removing existing bored pile foundation in a small space is to twist and break the existing bored pile foundation in segments through a full-rotation sleeve and an auxiliary part in a limited height range, and then recycle the broken pile / pieces until the entire pile foundation removal is completed. The segmented twisting and breaking is completed in a soundproof space formed by a sound barrier, and the noise generated during the segmented twisting and breaking process is lower than 75db.

[0006] Further, the segmented twisting and breaking specifically includes the following steps from top to bottom: S1) rotating the drill rig to the pile position; S2) the crawler crane places the sleeve into the rotary drill and drills into the sleeve; S3) the auxiliary part is arranged between the sleeve and the pile-breaking structure of the rotary drill; S4) the rotary drill rotates into the existing bored pile foundation to drive the twisted pile foundation; S5) the crawler crane lifts the sleeve, and the hammer head grab device recycles the broken pile / pieces; Repeat steps S3) to S5) until the entire existing bored pile foundation removal is completed.

[0007] Further, the step S4) specifically includes the following steps: S41) initial force application stage: the rotary drill rotates to gradually loosen the connection between the pile foundation and the surrounding soil layer; S42) insertion and pressurization stage: the auxiliary part is gradually inserted between the pile foundation and the rotary sleeve, and an increasing extrusion force is applied; Further, the step S42) inserting the pressurization phase is specifically by the wedge weight at the sleeve to increase the extrusion force constantly.

[0008] S43) stress concentration and fracture phase: the insertion and force application process of the auxiliary member causes local stress concentration of the pile foundation, and the pile foundation is broken, bent or directly twisted at the maximum stress point; S44) pile foundation twisting phase: when the auxiliary member is fully inserted and reaches the maximum force, the pile foundation is twisted at the breaking point, and the pile foundation is removed.

[0009] Further, the bottom of the auxiliary member forms an inclined friction surface, which produces a wedge effect at step S43), which causes stress concentration at the set point of the pile foundation, resulting in bending, breaking or direct twisting of the pile foundation.

[0010] Further, the existing bored pile foundation includes high-rise buildings, large bridges, urban old bridges or subway station construction beams.

[0011] Further, in construction, the ground elevation is +13.5m, and the average top elevation of the existing bored pile foundation to be removed is +9.0m.

[0012] Further, the sound insulation space is specifically a first enclosure space formed by a sound insulation barrier at the twisting position, and a second enclosure space formed by a dust screen above the first enclosure space, and the first enclosure space is partially located in the second enclosure space.

[0013] Further, the limited height range in the small space is specifically a construction environment with a maximum construction height of less than or equal to 17m.

[0014] The application of the existing bored pile foundation removal process in the small space as described above in the environmentally sensitive area, including the city or the ocean. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 The step of segmented twisting provided by the present application; Fig. 2 The structure diagram of adding a rotary drilling machine in the segmented twisting provided by the present application; Fig. 3 The structure diagram of adding a sleeve in the segmented twisting provided by the present application; Fig. 4 The structure diagram of adding an auxiliary member in the segmented twisting provided by the present application; Fig. 5 The state diagram of twisting in the segmented twisting provided by the present application; Fig. 6A structure diagram after torsion breaking in the segmented torsion breaking provided by the present application is shown; Fig.: 100, auxiliary part; 200, rotary drilling machine; 300, casing pipe; 400, existing bored pile foundation. DETAILED DESCRIPTION

[0016] The present application will be described in detail below with reference to the embodiments shown in the drawings, but it should be noted that these embodiments are not a limitation on the present application, and equivalent transformations or substitutions of function, method or structure made by those skilled in the art based on these embodiments are within the scope of protection of the present application.

[0017] Referring to the drawings, Figs. 1-6 The existing bored pile foundation removal process in the small space in the embodiment is specifically that, in a limited height range, the existing bored pile foundation 400 is torsion broken in sections by the full-rotation sleeve cooperating with the auxiliary part 100, and then the broken pile / pieces are recovered until the entire pile foundation removal is completed. The segmented torsion breaking is completed in the sound insulation space formed by the sound insulation barrier, and the noise generated in the segmented torsion breaking process is lower than 75 db. Specifically, in an application, the construction noise beside the machine is measured to be 73.4 db by using equipment monitoring, and the monitoring point near the building shows 71.3 db. In actual construction, the noise generated by the operation of the on-site generator is 80.3 db, and the noise generated by the operation of other cranes is 76.7 db, thereby significantly reducing the noise and avoiding the influence on residents.

[0018] The technical solution in the embodiment is used for a certain part of a confidential project in Singapore, and the specific introduction is as follows: First, project introduction.

[0019] The Cross Island Line (CRL) in the project will be the longest fully underground line in Singapore, with a total length of more than 50 kilometers. It will serve the existing and future developments of the eastern, western and northeastern corridors, connecting major hubs such as Jurong Lake District, Punggol Digital District and Changi area. There will be eight (8) interchange stations when it is in operation. This means that residents can choose more travel routes to reach their destinations. The second phase of CRL (CRL2) is about 15 kilometers long and includes six (6) underground stations. The CR208 metro interchange station project of the second phase of the Cross Island Metro Line in Singapore is the eighth route of the Singapore Metro, providing another alternative route for passengers currently taking the "East-West Line". The main content of the project is to design, coordinate and build the metro transfer station of the Cross Island Line (CR17). Due to the higher noise-related requirements in Singapore and the construction in the city, the environmental restrictions need to be fully considered, and in the pile foundation removal in the hard soil layer, deep pile foundation or complex environment, the requirements of the local environment and construction noise in Singapore need to be considered.

[0020] For the above project, the ground building has been demolished, but the pile foundation has not been removed. According to the overlap check of the diaphragm wall plan layout according to the new subway transfer station design profile and the original building pile foundation plan layout, there are 29 pile foundations mainly affecting the construction of the diaphragm wall, with pile diameters ranging from 0.3m to 1.2m, and the as-built drawings are incomplete, so it is impossible to determine the depth of the pile foundation and other information. In order to ensure the subsequent construction of the diaphragm wall, the 29 pile foundations that have been identified must be removed before the construction of the diaphragm wall. The construction height in this project is below 15m, and there are many existing buildings around the construction site, making the entire construction space narrow and limited.

[0021] For the pile pulling scheme in the prior art, it is generally as follows: (1) Hydraulic pile pulling machine: uses the huge pulling force generated by the hydraulic system to pull the pile out of the ground.

[0022] (2) Vibration pile pulling machine: reduces the friction between the pile and the soil through high-frequency vibration to achieve pile pulling.

[0023] (3) Static pressure pile pulling technology: uses static pressure to slowly pull the pile out of the ground, suitable for occasions with high requirements for the impact on the surrounding environment.

[0024] (4) Full-rotation casing pile pulling technology: full-rotation casing pile pulling technology refers to the use of a special rotating device (usually a casing drill) to insert or pull out the casing through rotation. This technology not only improves construction efficiency, but also effectively reduces the disturbance of pile foundation stress, helping to reduce the impact on the surrounding environment during construction. Compared with traditional static pile pulling or hammer pile pulling methods, full-rotation casing pile pulling technology has stronger adaptability and precise control ability.

[0025] In this project, the original ground elevation on site is +13.5m, and the average top elevation of the pile to be removed is +9.0m. The technology in this embodiment is to use wedge-shaped blocks to break the existing pile foundation into small sections for easy removal, and to operate under low clearance conditions. If the casing method is used alone, it needs to consider how to remove the pile after removing the soil around the pile. At this time, the length of the removed pile cannot be effectively controlled, making it difficult to carry out the construction. Therefore, the full-rotation casing method with wedge-shaped components needs to be considered in this embodiment, i.e. the auxiliary part in this embodiment is a wedge-shaped block. After using the above scheme in this embodiment, the segmented torsional breaking is as follows: S1) Rotate the drill to the pile position; S2) The caterpillar crane places the sleeve into the rotary drill and drills into the sleeve; S3) Set the auxiliary part between the sleeve and the rotary drill's pile breaking structure; S4) The rotary drill extends into the existing bored pile foundation and rotates, driving the torsional breaking pile foundation; The step S4) specifically comprises the following steps: S41) Initial force application stage: the rotary drilling rig rotates to drive the sleeve to rotate, gradually loosening the connection between the pile foundation and the surrounding soil; S42) Insertion and pressure application stage: the auxiliary member is gradually inserted between the pile foundation and the rotary sleeve, and an increasing extrusion force is applied, specifically, the increasing extrusion force is achieved by relying on the self-weight of the wedge during the insertion process.

[0026] S43) Stress concentration and rupture stage: the insertion and force application process of the auxiliary member causes local stress concentration of the pile foundation, and the pile foundation is broken, bent or directly twisted at the point of maximum stress; In this embodiment, the bottom of the auxiliary member 100 forms an inclined friction surface, which produces a wedge effect at step S43), which causes stress concentration at the set point of the pile foundation, resulting in bending, breaking or direct twisting of the pile foundation.

[0027] S44) Pile foundation twisting stage: when the auxiliary member 100 is fully inserted and reaches the maximum force, the pile foundation is twisted at the breaking point, and the pile foundation is removed.

[0028] S5) The crawler crane lifts the sleeve, and the hammer head grab device recovers the broken pile / pieces; Repeat steps S3) to S5) until the entire existing bored pile foundation removal is completed.

[0029] The working principle of the full-rotation sleeve pile pulling in the above scheme is as follows: The full-rotation sleeve is a device that contacts the surface of the pile foundation by rotating. It is usually made of steel and has a sleeve shape. Its core function is to generate friction by rotating and form strong contact with the surface of the pile foundation. The rotation of the rotary sleeve can achieve the following purposes: (1) Reduce friction: the rotation of the rotary sleeve can reduce the friction between the pile foundation and the soil, loosen the connection between the pile foundation and the surrounding soil. This can effectively reduce the resistance during pile pulling, making it easier to remove.

[0030] (2) Enhance the stability of the pile foundation: the rotating force of the rotary sleeve can be distributed around the pile foundation, helping to maintain the stability of the pile foundation and providing support for subsequent twisting operations.

[0031] (3) Local stress concentration: during rotation, the surface of the pile foundation will generate stress concentration due to rotation, laying the foundation for the insertion and destruction of the wedge-shaped member.

[0032] In this embodiment, the working principle of the auxiliary member 100 formed by the wedge-shaped member is as follows: The wedge-shaped member is a device with a wedge-shaped tip, used in conjunction with a rotary sleeve. Its main function is to generate concentrated stress through the gradual insertion of the gap between the pile foundation and the rotary sleeve, ultimately leading to the rupture or torsional fracture of the pile foundation. The specific process is as follows: (1) Insertion of force: While the rotary sleeve is rotating, the wedge-shaped member is gradually inserted between the pile foundation and the sleeve. The insertion of the wedge-shaped member will push the local area of the pile foundation outward, generating a destructive extrusion force.

[0033] (2) Wedge effect: The wedge-shaped member gradually expands the gap between the pile foundation and the surrounding soil, exerting increasing lateral pressure. This pressure generates strong stress concentration at a certain point of the pile foundation, leading to bending, rupture, or direct torsional fracture of the pile foundation.

[0034] (3) Torsional fracture effect: When the wedge-shaped member is fully inserted and sufficient pressure is applied, the pile foundation appears to be twisted or fractured at its stress point. The wedge-shaped member completes the physical destruction of the pile foundation by directly acting on the structural layer of the pile foundation.

[0035] The destruction mechanism of the torsional pile foundation in this embodiment is as follows: When the rotary sleeve and the wedge-shaped member work together, the destruction mechanism of the torsional pile foundation can be divided into the following stages: (1) Initial force application stage: The rotation of the rotary sleeve generates friction, gradually loosening the connection between the pile foundation and the surrounding soil. At this time, the wedge-shaped member has not been inserted, and the initial loosening of the pile foundation can reduce the resistance of subsequent operations.

[0036] (2) Insertion and pressure application stage: The wedge-shaped member is gradually inserted between the pile foundation and the rotary sleeve, and an increasing extrusion force is applied. As the wedge-shaped member is inserted, the stress point of the pile foundation begins to concentrate.

[0037] (3) Stress concentration and rupture stage: The insertion and force application process of the wedge-shaped member will cause local stress concentration of the pile foundation, resulting in cracks, bending, or direct torsional fracture at the point of maximum stress.

[0038] (4) Pile foundation torsional fracture stage: When the wedge-shaped member is fully inserted and reaches the maximum force, the pile foundation is torsionally fractured at the point of destruction, and the pile foundation is completely removed.

[0039] The full-rotation sleeve pile in this embodiment uses the following devices and equipment: 1) Full-rotation sleeve machine; For rotary casing machines, Nippon Sharyo RT200 and RT-150AII were selected based on the pile diameter range of 0.3m-1.2m to be removed. The RT200 can construct 1m~2m casing, with a deadweight of approximately 35t and dimensions of 4.8mX2.1mX2.1m. The maximum pullout force is 3450kN and the maximum downforce is 590kn+250kN. The RT-150AII can construct 0.8m~1.5m casing, with a deadweight of approximately 26t and dimensions of 4.2mX1.6mX2.1m. The maximum pullout force is 2050kN and the maximum downforce is 360kN+200kN.

[0040] 2) casing; The bottom of the casing is designed with a cutting drill bit and a cutting shoe.

[0041] 3) Hammer grab; Depending on the diameter of the pile to be removed, two types are available: SKD-20 and SKN-12. The SKD-20 has a deadweight of 4.85t and can clamp piles with a maximum diameter of 1.84m. The SKN-12 has a deadweight of 2.2t and can clamp piles with a maximum diameter of 1m.

[0042] 4) Auxiliary parts, i.e. wedge-shaped components; The wedge-shaped component is 0.63m long, 0.6m wide, 5.5m high and weighs 5.5t.

[0043] 5) Other equipment; A 75t crawler crane, a 120t crawler crane and a 320 excavator.

[0044] The full-rotation casing pile extraction process in this embodiment is as follows: (1) Survey and stake out, and mark the pile positions on site according to the plan; (2) Install the rotary drilling rig 200 directly on the pile position; (3) Use a crawler crane to place the casing 300 into the full-rotation drilling rig 200 and drill into the casing 300; (4) Insert a wedge-shaped member between the casing 300 and the pile-breaking structure (i.e., the existing bored pile foundation 400), and rotate the casing 300 to separate the piles; (5) Use hammer grab device to recover broken piles / debris; (6) Extending the casing by bolting and expanding the casing; (7) Repeat the above steps until all piles are removed; (8) Backfill the LSS to the ground with concrete buckets and remove all casings.

[0045] For noise control and dust control during construction, soundproof barriers and dust screens are set up. According to the current noise monitoring results on site, no additional soundproof barriers are needed during the day, and 30-meter static wind automatic fog cannon machines are used for dust control.

[0046] Specifically, it is a soundproof space, which specifically includes a first enclosure space formed by a soundproof barrier at the twist-off position, and a second enclosure space formed by a dust screen above the first enclosure space. The first enclosure space is partially located in the second enclosure space.

[0047] The equipment vibration level is not greater than 15 mm / s.

[0048] For broken pile and soil treatment, excavators are used to load and transport to designated disposal points.

[0049] The removal technology in this embodiment can be widely applied in the following fields: (1) Urban infrastructure construction: When old bridges in cities are demolished or subway stations are built, this technology can effectively avoid the impact of noise and vibration generated during construction on surrounding buildings.

[0050] (2) Large-scale infrastructure construction: For example, pile foundation demolition work of high-rise buildings, large bridges and other projects, which can effectively improve the demolition efficiency and ensure construction safety.

[0051] The process technology advantages in this embodiment include: (1) High efficiency: Compared with traditional pile pulling technology, using a full-rotation sleeve and wedge-shaped components to twist off the pile foundation can quickly disassemble the pile foundation, especially in complex geological conditions, it can more effectively break through the tight connection between the pile foundation and the soil layer.

[0052] (2) Low environmental disturbance: The technology produces less vibration and noise, effectively reducing the impact on the surrounding environment, especially suitable for environmentally sensitive areas such as cities or oceans.

[0053] (3) Strong adaptability: The combination of full-rotation sleeve and wedge-shaped components makes the technology adaptable to different pile foundation types, soil conditions and pile foundation depths. It has strong adaptability to pile foundations in hard soil or rock layers.

[0054] (4) High precision: Through precise mechanical control, it can achieve precise management of the pile foundation demolition process, reducing the risk of misoperation and potential safety risks.

[0055] The full-rotation sleeve wedge-shaped component torsional pile foundation technology is an innovative pile foundation removal method, which has significant advantages in construction efficiency, environmental protection, construction precision, etc. Through reasonable control of the force application process, combined with advanced equipment and technology, this technology can achieve efficient and safe pile foundation removal under complex geological conditions. With the continuous optimization and intelligent development of the technology, it will be widely used in more engineering projects in the future, promoting the technological progress in the field of engineering construction.

[0056] Referring to the accompanying Figs. 1-6 In this embodiment, the entire bored pile removal project is introduced as follows when it is applied specifically: 1. Bored pile removal procedure, positioning the crane.

[0057] First, place the base plate of the casing rotator, make sure the work platform must be flat and compacted. Check the position of the corner point according to the measurement point given by MainCo.

[0058] Mark the position of the base plate and place it in place.

[0059] Install the casing rotator (i.e. rotary drill 200) on top of the base plate.

[0060] Spot weld the base plate to the base plate of the casing rotator to reduce the movement of the rotator that may occur during operation.

[0061] Use the crane to lift the first reel of casing 300 with a shoe, insert the casing 300 into the casing rotator.

[0062] Drive the casing 300 through the obstacle by the casing rotator (i.e. rotary drill 200).

[0063] Use the first length of the driven casing to continue to extend the casing (by bolting) and cut it off when the bored pile structure is in place.

[0064] After drilling through the bored pile structure, ignite the wedge and place it into the casing. Block the wedge between the casing and the bored pile structure, rotate the casing to break it, and separate the broken piece from the bored pile structure.

[0065] Use the grab bucket to remove the debris and fragments of the bored pile.

[0066] After cutting the bored pile structure, lift the wedge and place it into the casing. Block the wedge between the casing and the bored pile structure, rotate the casing to break it, and separate the bored pile from the bored pile structure.

[0067] Use the grab bucket to remove the debris and fragments of the bored pile.

[0068] Set the grab bucket, place it into the casing. Use the grab bucket to grab the debris and fragments of the bored pile from the pit.

[0069] Use the broken pieces of the drilled pile to lift the grab bucket and discard the debris into the drilled tank.

[0070] Extend the casing and continue breaking and removing debris.

[0071] Bolt the extension casing and extend the casing. Repeat the above process to continue breaking the drilled pile and removing debris.

[0072] If necessary, use the clamp to break up large pieces of debris.

[0073] Install the clamp using the crane.

[0074] Place the clamp into the casing until it is in contact with the debris and extend the side panels of the clamp until they are in contact with the casing. Rotate the housing and use the soil breaker to further break up the debris into smaller pieces.

[0075] Use the grab bucket to remove the debris and pieces of the drilled pile.

[0076] Set up the grab bucket and use the grab bucket to remove the broken pieces.

[0077] Continue to dismantle the entire drilled pile structure; Repeat the above process until the entire drilled pile structure is cleaned up.

[0078] Move the machine and accessories to the next drilled pile location and repeat the dismantling.

[0079] The full-rotation casing pile extractor in the prior art is more suitable for ring cutting processes, and then it is more suitable for silty, sandy silt layers, and the like, and the diameter needs to be expanded, while the embodiment is more suitable for hard layers, and the cutting at the bottom of the casing 300 is completed, that is, the cutting is performed from top to bottom to segmentally twist and break, which is safer than the whole extraction in the prior art, and the perpendicularity and the like does not need to be considered too much. If the whole is extracted at one time, the perpendicularity of the casing 300 needs to be ensured, and the deviation in the extraction is avoided.

[0080] The scheme in the embodiment is also applied to the demolition of bridge plates and reinforced concrete piles, and the like, and the twisting and breaking of the pile foundation is performed skillfully, so that the extraction of the pile foundation is realized in multiple construction modes, especially in the pile foundation demolition in the city and the case of height limitation, and efficient, fast and safe construction is realized.

[0081] In the embodiment, the actual measurement of the machine is 73.4 db, and the monitoring point near the building shows 71.3 db (there are a generator 80.3 db and other cranes 76.7 db in operation on the site), and the noise requirements of a working day in Singapore are as shown in Table 1: The structure in this embodiment fully meets the above-mentioned noise requirements.

[0082] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0083] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0084] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. The process for removing existing bored pile foundations in a small space is characterized by: Within a limited height range, the existing bored pile foundation is twisted off in sections by using a full-rotation sleeve in conjunction with auxiliary parts, and the broken piles / fragments are then recovered until the entire pile foundation is removed; The segmented twisting is completed in the soundproof space formed by the sound insulation barrier, and the noise generated during the segmented twisting process is less than 75db.

2. The process for removing an existing bored pile foundation in a small space according to claim 1, characterized in that: The segmented twisting and breaking is specifically performed from top to bottom in the following steps: S1) The rotary drilling rig is placed at the pile position; S2) The crawler crane places the sleeve into the rotary drilling rig and drills into the sleeve; S3) arranging the auxiliary member between the sleeve and the pile breaking structure of the rotary drilling rig; S4) The rotary drilling rig is inserted into the existing bored pile foundation and rotates to break the pile foundation; S5) Crawler crane lifts sleeve and recovery hammer grab device recovers broken piles / fragments; Repeat steps S3) to S5) until the entire existing bored pile foundation is removed.

3. The process for removing an existing bored pile foundation in a small space according to claim 2, characterized in that: The step S4) specifically includes the following steps: S41) Initial force application stage: The rotary drill rotates, driving the sleeve to rotate, gradually loosening the connection between the pile foundation and the surrounding soil layer; S42) Insertion and pressurization stage: the auxiliary parts are gradually inserted between the pile foundation and the rotary casing, and an increasing squeezing pressure is applied; S43) Stress concentration and rupture stage: The insertion and force application of auxiliary components will cause local stress concentration in the pile foundation, and failure will occur at the point of maximum stress, causing the pile foundation to crack, bend or directly break; S44) Pile foundation twisting-off stage: When the auxiliary parts are fully inserted and the maximum force is reached, the pile foundation twists off at the failure point and the pile foundation is completely dismantled.

4. The process for removing an existing bored pile foundation in a small space according to claim 3, characterized in that: The insertion and pressurization stage in step S42) is specifically to continuously increase the squeezing force by the deadweight of the wedge block located at the sleeve.

5. The process for removing an existing bored pile foundation in a small space according to claim 3, characterized in that: The bottom of the auxiliary component forms an inclined friction surface, which produces a wedge effect in step S43 ), and the wedge effect causes stress concentration at the set point of the pile foundation, resulting in bending, cracking or direct twisting of the pile foundation.

6. The process for removing an existing bored pile foundation in a small space according to claim 1, characterized in that: The existing bored pile foundations include pile foundations in beams of high-rise buildings, large bridges, old urban bridges or subway stations.

7. The process for removing an existing bored pile foundation in a small space according to claim 1, characterized in that: During construction, the ground elevation was +13.5m, and the average elevation of the top of the existing bored cast-in-place pile foundations to be removed was +9.0m.

8. The process for removing an existing bored pile foundation in a small space according to claim 1, characterized in that: The soundproof space is specifically located at a first enclosed space formed by a soundproof barrier at the twist-off point, and a second enclosed space formed by a dustproof net above the first enclosed space, and the first enclosed space is partially located within the second enclosed space.

9. The process for removing an existing bored pile foundation in a small space according to claim 8, characterized in that: The restricted height range in the small space is specifically a construction environment where the maximum construction height is less than or equal to 17m.

10. Application of the process for removing existing bored pile foundations in a small space according to any one of claims 1 to 9 in environmentally sensitive areas, wherein the environmentally sensitive areas include cities or oceans.

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