Pile-forming construction method for isolation cast-in-place pile in ultra-low clearance shield crossing area under high-speed rail bridge

Abstract

The invention relates to the technical field of ultra-low clearance shields, and discloses a pile forming construction method for an isolation cast-in-place pile in an ultra-low clearance shield crossing area under a high-speed railway bridge, which comprises the following construction steps of: 1) forming an ultra-low clearance area between the high-speed railway bridge and a construction site, and measuring a setting-out positioning pile position in the construction site; (2) the full-rotation all-in-one machine enters the clearance area, the full-rotation all-in-one machine is provided with a rotation base and a horizontally-moving lifting device, and the lifting device lifts the pile casing to horizontally move to the position above the rotation base and conveys the lower portion of the pile casing into the rotation base; (3) after the pile casing is pressed into the construction site by a set depth through rotation, the pile casing is continuously pressed into the soil layer through rotation of the pressure feeder until the top of the pile casing is flush with the construction site; (4) drilling is conducted in the pile casing to form a pile hole, and after slurry in the pile hole is sucked and discharged into the slurry pool, the reverse circulation slewing drilling machine is evacuated from the clearance area; and (5) a reinforcement cage is put down, concrete is poured, and the concrete is solidified and combined with the pile casing to form the cast-in-place pile of an integrated structure.

Description

Technical Field

[0001] This invention patent relates to the technical field of ultra-low clearance shield tunneling, specifically to a method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunneling crossing area under a high-speed railway bridge. Background Technology

[0002] To meet the demands of economic development and improved transportation, high-speed rail networks in many cities are constantly expanding, leading to an increasing number of underground tunnel projects, many of which involve tunnels passing under existing high-speed rail bridges. To minimize the impact of construction on existing high-speed rail bridges, protective isolation piles are installed between the bridge piers and the tunnel boring machine (TBM) before construction begins.

[0003] Due to the impact of ultra-low headroom, low-headroom rotary drilling rigs and full-casing full-rotation drilling rigs cannot meet the requirements of on-site construction due to the limitation of construction height. Although low-headroom rotary drilling rigs can meet the headroom requirements, they cannot complete the pre-installation of deep and long casings, which brings difficulties to the drilling and pile formation of isolation piles. Summary of the Invention

[0004] The purpose of this invention is to provide a method for constructing isolation piles in ultra-low clearance shield tunneling areas under high-speed railway bridges, aiming to solve the problem of difficult construction of isolation piles under ultra-low clearance areas under high-speed railway bridges in the existing technology.

[0005] This invention is implemented as follows: a method for constructing isolation cast-in-place piles in ultra-low clearance shield tunnel crossing areas under high-speed railway bridges, comprising the following construction steps:

[0006] 1) An extremely low clearance zone is formed between the high-speed railway bridge and the construction site. The pile positions are measured and marked out at the construction site, and the pile positions are located outside the shield tunnel crossing area.

[0007] 2) The full-rotation integrated machine enters the clearance area. The bottom of the full-rotation integrated machine has a traveling mechanism. The full-rotation integrated machine has a slewing base and a horizontally moving hoist. The hoist is located above the slewing base. The hoist lifts the protective cylinder and moves it horizontally to the top of the slewing base, and sends the lower part of the protective cylinder into the slewing base.

[0008] 3) The rotary seat clamps the casing and presses it into the construction site to a set depth by rotating it. Then, the presser continues to rotate and press it into the soil until the top of the casing is level with the construction site. After that, the all-rotation integrated machine leaves the clearance area.

[0009] 4) The reverse circulation rotary drilling rig enters the clearance area, drills in the casing to form a pile hole, and pumps the mud in the pile hole to the mud pool. Then the reverse circulation rotary drilling rig leaves the clearance area.

[0010] 5) The steel cage is lowered into the pile hole by an excavator, and a grouting pipe is placed. Concrete is poured into the pile hole through the grouting pipe to a set height. The concrete solidifies and combines with the casing to form a cast-in-place pile.

[0011] Optionally, the construction site consists of a layer of miscellaneous fill, a layer of silty clay, and a layer of rock from top to bottom; in construction step 3), after the casing is pressed into the construction site to a set depth, the casing passes through the miscellaneous fill layer and extends into the silty clay layer.

[0012] Optionally, the fully rotating integrated machine has a horizontal guide rail, which is arranged above the slewing base, and the hoist is connected to the horizontal guide rail; in construction step 2), the protective casing moves along the horizontal guide rail to the top of the slewing base.

[0013] Optionally, the reverse circulation rotary drilling rig includes a drill rod, a vacuum pump, and a sand pump. The drill rod has a hollow cavity inside and a drill bit at the bottom.

[0014] In construction step 4), the drill rod rotates and drills in the casing, driving the drill bit to drill in the casing to form a pile hole. The vacuum pump assists the sand and gravel pump to suck up the hollow cavity and discharge the mud in the pile hole through the hollow cavity.

[0015] Optionally, in construction step 5), the reinforcing cage is formed by sequentially connecting multiple short cage sections. The excavator sequentially lowers the multiple short cage sections into the pile hole, and welds adjacent short cage sections to the top of the pile hole so that the multiple short cage sections form a reinforcing cage with an integral structure.

[0016] Optionally, there are piers supporting the high-speed railway bridge between the high-speed railway bridge and the construction site. In construction step 1), a fence is set around the outer perimeter of the pier, and a height warning line is set on the top of the high-speed railway bridge.

[0017] Optionally, the pressure feeder includes a pressure feed cylinder, the bottom of which has a docking structure that is fixed to the top of the protective cylinder; in construction step 3), after the docking structure of the pressure feed cylinder docks with the top of the protective cylinder, the rotary seat moves upward, clamps the pressure feed cylinder, drives the pressure feed cylinder to rotate and press in, and drives the protective cylinder to rotate and press in synchronously until the top of the protective cylinder is flush with the construction site.

[0018] Optionally, the docking structure includes multiple upper notches disposed at the bottom of the pressure feeding cylinder, the multiple upper notches being recessed upwards and arranged at intervals along the circumference of the pressure feeding cylinder, and upper protrusions formed between adjacent upper notches; the top of the protective cylinder is recessed downwards to form multiple lower notches, the multiple lower notches being arranged at intervals along the circumference of the protective cylinder, and lower protrusions formed between adjacent lower notches.

[0019] The pressure feeding cylinder has an annularly arranged inner reinforcing ring inside. The inner reinforcing ring extends along the circumference of the pressure feeding cylinder and is fixedly connected to the middle of multiple upper protrusions. The inner reinforcing ring has an inner suspended section that extends laterally across the upper notch.

[0020] In construction step 3), multiple upper protrusions are inserted into multiple lower notches from top to bottom, and multiple lower protrusions are inserted into multiple upper notches from bottom to top, thereby achieving docking and fixing of the pressure delivery cylinder and the protective cylinder; the inner suspended section presses against the inner sidewall of the lower protrusions from the inside to the outside.

[0021] Optionally, the outer periphery of the pressure feeding cylinder is provided with an annularly arranged outer reinforcing ring. The outer reinforcing ring extends along the circumference of the pressure feeding cylinder and is fixedly connected to the lower part of a plurality of upper protrusions. The outer reinforcing ring has an outer suspended section that extends laterally across the upper notch. The inner suspended section and the outer suspended section are arranged in a staggered manner.

[0022] In construction step 3), multiple upper protrusions are inserted into multiple lower notches from top to bottom, and multiple lower protrusions are inserted into multiple upper notches from bottom to top, thereby achieving docking and fixing of the pressure delivery cylinder and the protective cylinder; the outer suspended section presses against the outer side wall of the lower protrusion from the outside to the inside.

[0023] Optionally, the outer side of the inner suspended section is provided with a transversely arranged inner strip groove, the middle of the inner strip groove is provided with an inner elastic strip, the middle of the inner elastic strip is fixed to the middle of the inner strip groove, the two ends of the inner elastic strip are movably arranged, and there is an internal elastic gap between the inner elastic strip and the end of the inner strip groove.

[0024] The inner side of the outer suspended section is provided with a transversely arranged outer strip groove. The middle part of the outer strip groove is provided with two outer elastic strips. The outer ends of the two outer elastic strips are respectively fixedly connected to the end of the outer strip groove. The inner ends of the outer elastic strips extend toward the middle of the outer strip groove, and there is an external elastic gap between the inner ends of the two outer strip grooves.

[0025] The outer elastic intervals are aligned with the inner elastic strips, and the two inner elastic intervals are respectively aligned with the two outer elastic strips.

[0026] In construction step 3), after the lower protrusion is inserted into the upper notch, the inner elastic strip abuts against the inner wall of the lower protrusion from the inside out and is under compression deformation, and the outer elastic strip abuts against the outer wall of the lower protrusion from the outside in and is under compression deformation.

[0027] During the drilling process where the pressure cylinder drives the casing to rotate, the inner elastic strip is subjected to circumferential compression and deforms towards the inner elastic interval, while the outer elastic strip is subjected to circumferential compression and deforms towards the outer elastic interval.

[0028] Compared with existing technologies, the present invention provides a method for constructing isolation cast-in-place piles in ultra-low clearance shield tunneling zones under high-speed railway bridges. This method isolates the shield tunneling zone from the high-speed railway bridge piers by constructing cast-in-place piles, ensuring the safety of the high-speed railway bridge during shield tunneling. A fully rotating integrated machine enters the clearance zone, and a short casing section is sunk to a set depth using a slewing base. A horizontally moving hoist then lifts the next short casing section to the top, enabling rapid casing extension in ultra-low clearance zones without the need for large cranes. Subsequently, a permanent casing wall effectively prevents the collapse of the upper backfill layer from harming the bridge. Simultaneously, the permanent casing serves as permanent protection for the pile body, effectively improving the pile's bearing capacity and ensuring the quality of pile construction. Attached Figure Description

[0029] Figure 1 This is a structural schematic diagram of the high-speed railway bridge and construction site provided by the present invention;

[0030] Figure 2 This is a construction diagram of the all-rotation integrated machine provided by the present invention;

[0031] Figure 3 This is a three-dimensional schematic diagram of the protective sleeve and the pressure feeding cylinder provided by the present invention;

[0032] Figure 4 This is a three-dimensional schematic diagram of the protective sleeve and the pressure feeding cylinder provided by the present invention;

[0033] Figure 5 This is a front view schematic diagram of the inner strip groove provided by the present invention;

[0034] Figure 6 This is a front view schematic diagram of the outer strip groove provided by the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0037] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0038] Reference Figure 1-6 The image shown is a preferred embodiment of the present invention.

[0039] The present invention provides a method for constructing isolation cast-in-place piles in ultra-low clearance shield tunnel crossing areas under high-speed railway bridges, comprising the following construction steps:

[0040] 1) An ultra-low clearance zone 101 is formed between the high-speed railway bridge 100 and the construction site. The pile positions are located on the outside of the shield tunnel crossing zone 102.

[0041] 2) The full-rotation integrated machine 200 enters the clearance area 101. The bottom of the full-rotation integrated machine 200 has a traveling mechanism 210. The full-rotation integrated machine 200 has a slewing base 230 and a horizontally moving hoist 220. The hoist 220 is located above the slewing base 230. The hoist 220 hoists the protective cylinder 300 and moves it horizontally to the top of the slewing base 230, and sends the lower part of the protective cylinder 300 into the slewing base 230.

[0042] 3) The slewing seat 230 clamps the casing 300 and presses the casing 300 into the construction site to a set depth by rotating. Then, the press feeder continues to rotate and press it into the soil until the top of the casing 300 is flush with the construction site. Then, the all-rotation integrated machine 200 is removed from the clearance area 101.

[0043] 4) The reverse circulation rotary drilling rig enters the clearance area 101, drills in the casing 300 to form a pile hole, and pumps the mud in the pile hole to the mud pool. Then the reverse circulation rotary drilling rig leaves the clearance area 101.

[0044] 5) The steel cage is lowered into the pile hole by an excavator, and a grouting pipe is placed. Concrete is poured into the pile hole through the grouting pipe to the set height. The concrete solidifies and forms a cast-in-place pile 120 that is integrated with the casing 300.

[0045] The aforementioned method for constructing isolation piles in the ultra-low clearance shield tunneling zone under the high-speed railway bridge 100 uses cast-in-place piles 120 to isolate the shield tunneling zone 102 from the piers 110 of the high-speed railway bridge 100, ensuring the safety of the high-speed railway bridge 100 during the shield tunneling process. A fully rotating integrated machine 200 enters the clearance zone 101, and a section of the casing is sunk to a set depth using a slewing seat 230. A horizontally moving hoist 220 then lifts the next short section of the casing to the top, enabling rapid extension of the casing 300 in the ultra-low clearance zone 101 without the need for a large crane. Subsequently, the permanent casing 300 serves as a protective wall, effectively preventing the collapse of the upper backfill layer from harming the bridge. Simultaneously, the permanent casing 300 provides permanent protection for the pile body, effectively improving the pile's bearing capacity and ensuring the quality of the pile construction.

[0046] The 200 fully rotary integrated machine used in this construction method can independently complete the processes of self-positioning, hoisting of the casing 300, and rotary pressing. The construction is continuous and efficient. After the casing 300 of the construction section is sunk into place, the reverse circulation rotary drilling rig takes over to drill the hole. The 200 fully rotary integrated machine moves to the next construction section to carry out the casing 300 sinking operation. The pile construction operations do not interfere with each other, and the combined flow construction is continuous and efficient.

[0047] The reverse circulation rotary drilling method uses mud wall protection and air lift reverse circulation slag removal throughout the entire process, resulting in stable borehole walls and less sediment at the bottom of the hole.

[0048] In this embodiment, in construction step 2), after setting the pile location marks for the construction section, an excavator is used to excavate a trench with a depth of 2.0m along the marks so that the first section of the casing of the cast-in-place pile 120 can be buried at one time. The first section of the casing is 2.3m long, and a 30cm long and 4cm thick tube shoe is added to its bottom. Alloy cutter teeth are provided at the bottom, and the outer diameter of the tube shoe exceeds the casing by 2cm.

[0049] During the initial casing insertion process, diaphragm cutting drilling is performed to provide a 2cm soil gap for the initial casing, reducing the external frictional resistance and making it easier for subsequent casings to sink. After the trench section is excavated, an excavator lifts each initial casing section into the trench, and the position of the initial casing is then checked and verified. Once the requirements are met, the soil is backfilled, compacted, and installed.

[0050] Next, the full-rotation integrated machine 200 was positioned on site. Steel plates were laid in the positioning area beforehand to ensure stable operation. After aligning the slewing mechanism of the full-rotation integrated machine 200 with the first section of the casing, the upper platform of the slewing mechanism was lowered to its lowest point via the hydraulic system. The hook was then positioned above the casing 300, and the winch was released to lower the hook, connecting it to the first section of the casing. The winch was then slowly retracted to lift the first section of the casing, which was already buried underground, and raised it until its top was approximately 10cm above the upper platform of the slewing mechanism. At this point, the slewing seat 230 clamped the casing 300. After releasing the lifting gear, the casing 300 was extended and then pressed down. This extension and pressing operation was repeated until the bottom of the casing 300 reached the set depth.

[0051] Specifically, the construction site consists of a layer of miscellaneous fill, a layer of silty clay, and a layer of rock from top to bottom; in construction step 3), after the casing 300 is pressed into the construction site to a set depth, the casing 300 passes through the miscellaneous fill layer and extends into the silty clay layer.

[0052] The full-rotation integrated machine 200 has a horizontal guide rail 221, which is arranged above the slewing seat 230. The hoist 220 is connected to the horizontal guide rail 221. In construction step 2), the protective casing 300 moves along the horizontal guide rail 221 to the top of the slewing seat 230.

[0053] In this embodiment, a grab bucket is connected to the horizontal guide rail 221. In construction step 3), the grab bucket moves back and forth along the horizontal guide rail 221, grabbing and unloading the soil from the casing 300. Thus, during drilling, the grab bucket is connected to the horizontal guide rail 221 and moved above the casing 300 to grab the soil from within the casing 300, achieving soil removal and unloading within the casing 300, enabling continuous and efficient multi-stage construction. By cleverly utilizing the horizontal guide rail 221 and the hoist 220, vertical hoisting is transformed into horizontal hoisting, overcoming the limitations of low clearance and ensuring the normal progress of construction.

[0054] In a preferred embodiment, the reverse circulation rotary drilling rig includes a drill rod, a vacuum pump, and a sand pump. The drill rod has a hollow cavity inside and a drill bit at the bottom.

[0055] In construction step 4), the drill rod rotates and drills within the casing 300, driving the drill bit to drill into the casing 300 to form a pile hole. A vacuum pump assists the sand and gravel pump to suction the hollow cavity, discharging the mud from the pile hole through the hollow cavity. This method is more efficient and faster than using a grab bucket for soil removal and hole cleaning, and can be further improved by using a vacuum pump for suction.

[0056] In construction step 5), the reinforcing cage is formed by sequentially connecting multiple short cage sections. The excavator sequentially lowers these short cage sections into the pile hole, and welds adjacent short cage sections at the top of the pile hole to form a single, integrated reinforcing cage structure. This achieves the reinforcing cage structure below the ultra-low clearance zone 101.

[0057] Specifically, there is a pier 110 supporting the high-speed railway bridge 100 between the high-speed railway bridge 100 and the construction site. In construction step 1), a fence is set around the outer perimeter of the pier 110, and a height warning line is set on the top of the high-speed railway bridge 100.

[0058] The pressure feeder includes a pressure feed cylinder 400, the bottom of which has a docking structure that connects and fixes to the top of the protective cylinder 300. In construction step 3), after the docking structure of the pressure feed cylinder 400 connects with the top of the protective cylinder 300, the rotary seat 230 moves upward, clamps the pressure feed cylinder 400, drives the pressure feed cylinder 400 to rotate and press in, and drives the protective cylinder 300 to rotate and press in synchronously until the top of the protective cylinder 300 is flush with the construction site. In this way, the pressure feed cylinder 400 and the protective cylinder 300 are fixedly connected through the docking structure, making them longer, and the top of the protective cylinder 300 can be pressed in until it is flush with the construction site.

[0059] Specifically, the docking structure includes multiple upper notches 411 at the bottom of the pressure feeding cylinder 400, the multiple upper notches 411 being recessed upwards and arranged at intervals along the circumference of the pressure feeding cylinder 400, and upper protrusions 410 formed between adjacent upper notches 411; the top of the protective cylinder 300 is recessed downwards to form multiple lower notches 311, the multiple lower notches 311 being arranged at intervals along the circumference of the protective cylinder 300, and lower protrusions 310 formed between adjacent lower notches 311;

[0060] The pressure feeding cylinder 400 has an annularly arranged inner reinforcing ring 420 inside. The inner reinforcing ring 420 extends along the circumference of the pressure feeding cylinder 400 and is fixedly connected to the middle of a plurality of upper protrusions 410. The inner reinforcing ring 420 has an inner suspended section that extends laterally across the upper notch 411.

[0061] In construction step 3), multiple upper protrusions 410 are inserted into multiple lower notches 311 from top to bottom, and multiple lower protrusions 310 are inserted into multiple upper notches 411 from bottom to top, thus achieving the docking and fixing of the pressure delivery cylinder 400 and the protective cylinder 300; the inner suspended section presses against the inner sidewall of the lower protrusions 310 from the inside out. In this way, through the design of the mutually cooperating upper protrusions 410 and lower notches 311, as well as the design of the lower protrusions 310 and upper notches 411, a flat docking between the protective cylinder 300 and the pressure delivery cylinder 400 is achieved. Then, through the design of the inner reinforcing ring 420, it plays a positioning role during docking, facilitating quick alignment.

[0062] In this embodiment, the outer periphery of the pressure feeding cylinder 400 is provided with an annular outer reinforcing ring 430. The outer reinforcing ring 430 extends along the circumference of the pressure feeding cylinder 400 and is fixedly connected to the lower part of multiple upper protrusions 410. The outer reinforcing ring 430 has an outer suspended section that extends laterally across the upper notch 411, and the inner suspended section and the outer suspended section are arranged in a staggered manner.

[0063] In construction step 3), multiple upper protrusions 410 are inserted into multiple lower notches 311 from top to bottom, and multiple lower protrusions 310 are inserted into multiple upper notches 411 from bottom to top, achieving docking and fixing of the pressure cylinder 400 and the protective cylinder 300; the outer suspended section presses against the outer wall of the lower protrusion 310 from the outside to the inside. In this way, the design of the outer reinforcing ring 430 restricts the lateral movement of the lower protrusion 310 passing through the outer reinforcing ring 430, achieving positioning and installation.

[0064] In this embodiment, an inner strip groove 421 is provided on the outer side of the inner suspended section, and an inner elastic strip 422 is provided in the middle of the inner strip groove 421. The middle part of the inner elastic strip 422 is fixed in the middle of the inner strip groove 421, and the two ends of the inner elastic strip 422 are movably arranged and have an internal elastic gap with the end of the inner strip groove 421.

[0065] The inner side of the outer suspended section is provided with a transversely arranged outer strip groove 431. Two outer elastic strips 432 are provided in the middle of the outer strip groove 431. The outer ends of the two outer elastic strips 432 are respectively fixedly connected to the ends of the outer strip groove 431. The inner ends of the outer elastic strips 432 extend toward the middle of the outer strip groove 431, and there is an external elastic gap between the inner ends of the two outer strip grooves 431.

[0066] The outer elastic intervals are aligned with the inner elastic strips 422, and the two inner elastic intervals are respectively aligned with the two outer elastic strips 432.

[0067] In construction step 3), after the lower protrusion 310 is inserted into the upper notch 411, the inner elastic strip 422 abuts against the inner side wall of the lower protrusion 310 from the inside out and is under compression deformation, and the outer elastic strip 432 abuts against the outer side wall of the lower protrusion 310 from the outside in and is under compression deformation.

[0068] During the rotary drilling process of the pressure feed cylinder 400 driving the casing 300, the inner elastic strip 422 is subjected to circumferential compression, deforming towards the inward elastic interval, while the outer elastic strip 432 is subjected to circumferential compression, deforming towards the outward elastic interval. Subsequently, the inner and outer elastic strips 422 and 432 press against the inner and outer walls of the lower protrusion 310 respectively during docking, creating additional compressive force. This compressive force helps enhance the docking stability between the pressure feed cylinder 400 and the casing 300. During the rotary pressing process of the pressure feed cylinder 400 driving the casing 300, especially when encountering harder geological layers, significant impact forces and vibrations are generated. The compression deformation of the inner and outer elastic strips 422 and 432 can absorb some of the horizontal impact energy, acting as a buffer and shock absorber, protecting the docking structure from damage, and also extending the service life of the equipment.

[0069] Due to the unevenness of geological conditions, the casing 300 may encounter soil layers of varying hardness during the pressing process. The elastic deformation of the inner elastic strip 422 and the outer elastic strip 432 allows for a certain relative displacement between the pressing cylinder 400 and the casing 300, thereby automatically adapting and adjusting the docking state to ensure the tightness and stability of the docking.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge, characterized in that, The construction steps include the following: 1) An extremely low clearance zone is formed between the high-speed railway bridge and the construction site. The pile positions are measured and marked out at the construction site, and the pile positions are located outside the shield tunnel crossing area. 2) The full-rotation integrated machine enters the clearance area. The bottom of the full-rotation integrated machine has a traveling mechanism. The full-rotation integrated machine has a slewing base and a horizontally moving hoist. The hoist is located above the slewing base. The hoist lifts the protective cylinder and moves it horizontally to the top of the slewing base, and sends the lower part of the protective cylinder into the slewing base. 3) The rotary seat clamps the casing and presses it into the construction site to a set depth by rotating it. Then, the presser continues to rotate and press it into the soil until the top of the casing is level with the construction site. After that, the all-rotation integrated machine leaves the clearance area. 4) The reverse circulation rotary drilling rig enters the clearance area, drills in the casing to form a pile hole, and pumps the mud in the pile hole to the mud pool. Then the reverse circulation rotary drilling rig leaves the clearance area. 5) The steel cage is lowered into the pile hole by an excavator, and a grouting pipe is placed. Concrete is poured into the pile hole through the grouting pipe to a set height. The concrete solidifies and combines with the casing to form a cast-in-place pile.

2. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 1, characterized in that, The construction site consists of a layer of miscellaneous fill, a layer of silty clay, and a layer of rock from top to bottom. In construction step 3), after the casing is pressed into the construction site to a set depth, the casing passes through the miscellaneous fill layer and extends into the silty clay layer.

3. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 1, characterized in that, The fully rotating integrated machine has a horizontal guide rail, which is arranged above the rotating base, and the hoist is connected to the horizontal guide rail; in construction step 2), the protective casing moves along the horizontal guide rail to the top of the rotating base.

4. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 1, characterized in that, The reverse circulation rotary drilling rig has a drill rod, a vacuum pump, and a sand pump. The drill rod has a hollow cavity inside and a drill bit at the bottom. In construction step 4), the drill rod rotates and drills in the casing, driving the drill bit to drill in the casing to form a pile hole. The vacuum pump assists the sand and gravel pump to suck up the hollow cavity and discharge the mud in the pile hole through the hollow cavity.

5. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 1, characterized in that, In construction step 5), the steel cage is formed by sequentially connecting multiple short cage sections. The excavator sequentially lowers the multiple short cage sections into the pile hole and welds adjacent short cage sections at the top of the pile hole so that the multiple short cage sections form a steel cage with an integral structure.

6. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 1, characterized in that, The high-speed railway bridge is supported by piers between itself and the construction site. In construction step 1), a fence is set around the outer perimeter of the piers, and a height warning line is set at the top of the high-speed railway bridge.

7. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in any one of claims 1 to 6, characterized in that, The pressure feeder includes a pressure feed cylinder, the bottom of which has a docking structure that is fixed to the top of the protective cylinder; in construction step 3), after the docking structure of the pressure feed cylinder docks with the top of the protective cylinder, the rotary seat moves upward, clamps the pressure feed cylinder, drives the pressure feed cylinder to rotate and press in, and drives the protective cylinder to rotate and press in synchronously until the top of the protective cylinder is flush with the construction site.

8. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 7, characterized in that, The docking structure includes multiple upper notches at the bottom of the pressure feeding cylinder, the multiple upper notches being recessed upwards and arranged at intervals along the circumference of the pressure feeding cylinder, with upper protrusions formed between adjacent upper notches; the top of the protective cylinder is recessed downwards to form multiple lower notches, the multiple lower notches being arranged at intervals along the circumference of the protective cylinder, with lower protrusions formed between adjacent lower notches. The pressure feeding cylinder has an annularly arranged inner reinforcing ring inside. The inner reinforcing ring extends along the circumference of the pressure feeding cylinder and is fixedly connected to the middle of multiple upper protrusions. The inner reinforcing ring has an inner suspended section that extends laterally across the upper notch. In construction step 3), multiple upper protrusions are inserted into multiple lower notches from top to bottom, and multiple lower protrusions are inserted into multiple upper notches from bottom to top, thereby achieving docking and fixing of the pressure delivery cylinder and the protective cylinder; the inner suspended section presses against the inner sidewall of the lower protrusions from the inside to the outside.

9. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 8, characterized in that, The outer periphery of the pressure feeding cylinder is provided with an annular outer reinforcing ring. The outer reinforcing ring extends along the circumference of the pressure feeding cylinder and is fixedly connected to the lower part of multiple upper protrusions. The outer reinforcing ring has an outer suspended section that extends laterally across the upper notch. The inner suspended section and the outer suspended section are arranged in a staggered manner. In construction step 3), multiple upper protrusions are inserted into multiple lower notches from top to bottom, and multiple lower protrusions are inserted into multiple upper notches from bottom to top, thereby achieving docking and fixing of the pressure delivery cylinder and the protective cylinder; the outer suspended section presses against the outer side wall of the lower protrusion from the outside to the inside.

10. The method for constructing isolation cast-in-place piles in the ultra-low clearance shield tunnel crossing area under a high-speed railway bridge as described in claim 9, characterized in that, The outer side of the inner suspended section is provided with a transversely arranged inner strip groove, and the middle part of the inner strip groove is provided with an inner elastic strip. The middle part of the inner elastic strip is fixed to the middle part of the inner strip groove, and the two ends of the inner elastic strip are movably arranged and have an internal elastic gap with the end of the inner strip groove. The inner side of the outer suspended section is provided with a transversely arranged outer strip groove. The middle part of the outer strip groove is provided with two outer elastic strips. The outer ends of the two outer elastic strips are respectively fixedly connected to the end of the outer strip groove. The inner ends of the outer elastic strips extend toward the middle of the outer strip groove, and there is an external elastic gap between the inner ends of the two outer strip grooves. The outer elastic intervals are aligned with the inner elastic strips, and the two inner elastic intervals are respectively aligned with the two outer elastic strips. In construction step 3), after the lower protrusion is inserted into the upper notch, the inner elastic strip abuts against the inner wall of the lower protrusion from the inside out and is under compression deformation, and the outer elastic strip abuts against the outer wall of the lower protrusion from the outside in and is under compression deformation. During the drilling process where the pressure cylinder drives the casing to rotate, the inner elastic strip is subjected to circumferential compression and deforms towards the inner elastic interval, while the outer elastic strip is subjected to circumferential compression and deforms towards the outer elastic interval.

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