A protective device for rotary bored piles in silty areas

Abstract

This invention discloses a protective device for rotary-drilled cast-in-place piles in silty areas, comprising a support cylinder and several retaining cylinders. The support cylinder is installed at the upper end of the pile hole. Upper connecting seats are provided on both the left and right sides of the upper end of the retaining cylinder, and lower connecting seats are provided on both the front and rear sides of the lower end of the retaining cylinder. An axial splicing mechanism corresponding to the upper connecting seat is provided on the lower connecting seat. When two adjacent retaining cylinders abut against each other, the axial splicing mechanism automatically completes the locking connection between the adjacent retaining cylinders under vertical pressure. Positioning channels are provided on both sides of the inner wall of the support cylinder, including a first positioning groove, a transition groove, and a second positioning groove. This invention achieves precise splicing and settlement of retaining cylinders in silty strata through a three-level positioning channel coordinated guidance and an axial self-locking splicing mechanism, thus constructing a continuous support column.

Description

Technical Field

[0001] This invention relates to the field of cast-in-place pile technology, specifically a protective device for rotary cast-in-place piles in silty areas. Background Technology

[0002] When a bored cast-in-place concrete pile needs to pass through soft soil layers such as quicksand or silt, a steel casing can be used to protect the borehole wall to prevent the borehole from collapsing during drilling and concrete pouring.

[0003] Due to height limitations of the steel casing settling equipment and length limitations of the steel casing transport vehicles, the length of a single steel casing section cannot be too long. When a large length of steel casing is required, it is generally necessary to manufacture the steel casing in sections and then extend each section.

[0004] Currently, steel casings are generally connected by welding on site. The overall strength, rigidity and sealing performance of the extended steel casing can be guaranteed. However, a lot of welding work is required on site, which results in low construction efficiency. If the length is too long, the difficulty of welding and inserting the steel casing will increase. Moreover, when the steel casing is recycled, it needs to be cut at the weld and re-sectioned with gas cutting. After repeated welding and cutting, the steel casing is damaged and destroyed, resulting in a short service life. Summary of the Invention

[0005] The purpose of this invention is to provide a protective device for rotary drilling piles in silty areas, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a protective device for rotary bored piles in silt areas, comprising a support cylinder and several retaining cylinders. The support cylinder is used to be installed at the pile opening at the upper end of the pile hole. The upper left and right sides of the upper end of the retaining cylinder are provided with upper connecting seats, and the lower front and rear sides of the lower end of the retaining cylinder are provided with lower connecting seats. The lower connecting seats are provided with axial splicing mechanisms corresponding to the upper connecting seats. When two adjacent retaining cylinders abut against each other, the axial splicing mechanisms on them automatically complete the locking connection of the adjacent retaining cylinders under the vertical pressure drive.

[0007] Positioning channels are provided on both sides of the inner wall of the support cylinder. The positioning channels include a first positioning groove, a transition groove, and a second positioning groove. The size of the transition groove is adapted to the size of the upper connecting seat and the lower connecting seat after splicing. The first positioning groove is opened vertically on the upper part of the inner wall of the support cylinder, the transition groove is opened horizontally on the middle part of the inner wall of the support cylinder, and the second positioning groove is opened vertically on the lower part of the inner wall of the support cylinder. The first positioning groove and the second positioning groove are respectively connected to the two sides of the transition groove. The lower connecting seat of the first support cylinder descends vertically along the first positioning groove, rotates into the transition groove, and then sinks down to the end of the second positioning groove. At this time, the upper connecting seat is simultaneously mounted on the transition groove. After the subsequent cylinder is lowered and axial splicing is triggered, the positioning channel guidance process is repeated to form a continuous support cylinder column extending downward from the support cylinder.

[0008] Furthermore, a ring frame is rotatably embedded inside the support cylinder, and a gear ring is fitted on the outer wall of the ring frame. A motor is installed at the top of the support cylinder, and the output shaft of the motor extends through the support cylinder and has a gear at its end that meshes with the gear ring. Each of the first positioning slots has a receiving slot on its side wall. A through slot is horizontally opened in the middle of the transition slot. The inner end face of the through slot extends to communicate with the inner wall of the ring frame, and one end of the through slot extends to communicate with the corresponding receiving slot. Supports are provided on both the front and rear sides of the inner wall of the ring frame. The other end of the support passes through the through slot and has an arc-shaped push plate at its end. The arc-shaped push plate can move from the receiving slot to the second positioning slot under the drive of the ring frame, thereby pushing the lower connecting seat of the support cylinder to move horizontally, so that it can accurately transition from the first positioning slot position to the second positioning slot, realizing the automated switching of the settlement path of the support cylinder.

[0009] Furthermore, guide blocks are provided on both the left and right sides of the top of the support cylinder. The guide blocks have guide grooves on their inner sides that are adapted to the upper and lower connecting seats. The guide grooves are connected to the first positioning grooves. The structure of the guide grooves is a progressively contracting shape from top to bottom.

[0010] Furthermore, the axial splicing mechanism includes a connecting block and locking blocks disposed on both sides of the connecting block. Grooves are provided on both sides of the bottom of the connecting block, and the locking blocks are slidably fitted into the corresponding grooves. A spring is connected between the inner end of the locking block and the groove. A connecting port adapted to the connecting block is provided at the top of the upper connecting seat, and locking holes adapted to the locking blocks are provided on both the left and right sides of the inner wall of the connecting port. Several sliding rods are provided inside the lower connecting seat, and the connecting block is slidably fitted into the lower connecting seat via the sliding rods. A first lead screw is rotatably disposed in the center of the lower connecting seat, and the first lead screw is threadedly connected to the connecting block. A first slot is provided on the outer end face of the lower connecting seat, and a first knob is rotatably disposed within the first slot. The rotating shaft of the first knob extends through and is connected to the first lead screw via a bevel gear transmission.

[0011] Furthermore, unlocking blocks are slidably fitted into the card holes on both sides, and a bidirectional lead screw is rotatably provided at the bottom of the connection port. The unlocking blocks on both sides are threadedly connected to the two sides of the bidirectional lead screw respectively. A second slot is provided on the outer end face of the upper connecting seat, and a second knob is rotatably provided in the second slot. The rotating shaft of the second knob extends through and is connected to the bidirectional lead screw through a bevel gear transmission.

[0012] Furthermore, a first adjustment groove is formed in the area from the bottom of the first positioning groove to the bottom of the support cylinder, and the first adjustment groove is connected to the first positioning groove; a second adjustment groove is formed in the area from the top of the second positioning groove to the top of the support cylinder, and the second adjustment groove is connected to the second positioning groove; a first adjustment plate is slidably embedded in the first adjustment groove, and a first airbag is connected between the first adjustment groove and the first adjustment plate; a second adjustment plate is slidably embedded in the second adjustment groove, and a second airbag is connected between the second adjustment groove and the second adjustment plate; an air pipe is provided at the top of the support cylinder, and a control valve is provided on the air pipe; the other end of the air pipe is connected to each of the first and second airbags through several branch pipes; the bottoms of the first and second adjustment plates are both inclined structures.

[0013] Furthermore, both the top end of the upper connecting seat and the bottom end of the lower connecting seat are provided with mud-guiding inclined surfaces, and both the left and right ends of the mud-guiding inclined surfaces of the lower connecting seat are provided with chamfered structures orthogonal to the rotation direction of the support cylinder.

[0014] Furthermore, a sealing edge is provided at the top of the support cylinder, the sealing edge is located inside the upper connecting seat, and a sealing groove adapted to the sealing edge is provided at the bottom of the support cylinder.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. This invention achieves precise splicing and settlement of support cylinders in silty soil strata through a three-level positioning channel coordinated guidance and axial self-locking splicing mechanism; the first support cylinder is lowered through the first positioning groove, rotated through the transition groove, and settled twice through the second positioning groove to form a spatial misalignment fulcrum, and the subsequent cylinder is automatically locked by spring blocks when it is lowered, thus constructing a continuous support column; moreover, this device achieves settlement work simultaneously during the splicing process, realizing a continuous operation closed loop of "settling upon splicing", providing unprecedented process stability and timeliness guarantee for the construction of ultra-deep piles in soft soil layers.

[0017] 2. By instantaneously engaging the lower connecting seat spring block with the upper connecting seat locking hole, the traditional welding process is replaced, greatly improving the splicing efficiency of a single support cylinder. Furthermore, by replacing welding with an axial mechanical self-locking mechanism, instant splicing and non-destructive disassembly and recycling of the support cylinder are achieved, completely avoiding thermal damage and cutting damage.

[0018] 3. The progressive guide groove at the top of the support cylinder, combined with the positioning groove design, corrects the initial posture error of the support cylinder. The electromechanical drive push plate precisely switches the settlement path, completely solving the stubborn problems of support cylinder offset, jamming, and grout leakage in traditional processes. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the assembled structure of the protective device of the present invention;

[0020] Figure 2 This is an exploded view of the protective device of the present invention;

[0021] Figure 3 This is a schematic diagram of the ring frame structure of the present invention;

[0022] Figure 4 This is a top view of the ring frame installation of the present invention;

[0023] Figure 5 This is a schematic diagram of the support cylinder structure of the present invention;

[0024] Figure 6 This is a schematic diagram of the lower connecting seat structure of the present invention;

[0025] Figure 7 This is a schematic diagram of the upper connecting seat structure of the present invention;

[0026] Figure 8 This is a cross-sectional view of the support cylinder structure of the present invention.

[0027] In the diagram, the components are: support cylinder-1, support cylinder-2, upper connecting seat-3, lower connecting seat-4, first positioning groove-5, transition groove-6, second positioning groove-7, ring frame-8, gear ring-9, motor-10, storage groove-11, through groove-12, bracket-13, arc-shaped push plate-14, guide block-15, guide groove-16, connecting block-17, locking block-18, groove-19, spring-20, connection port-21, locking hole-22, slide rod-23, first lead screw-24, first knob-25, unlocking block-26, bidirectional lead screw-27, second knob-28, first adjusting plate-29, second adjusting plate-30, air pipe-31, control valve-32, and sealing edge-33. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figures 1 to 8As shown, a protective device for rotary bored piles in silty areas includes a support cylinder 1 and several support cylinders 2. The support cylinder 1 is used to install at the pile opening at the upper end of the pile hole. The upper left and right sides of the upper end of the support cylinder 2 are provided with upper connecting seats 3, and the lower front and rear sides of the lower end of the support cylinder 2 are provided with lower connecting seats 4. The lower connecting seats 4 are provided with an axial splicing mechanism corresponding to the upper connecting seats 3. When two adjacent support cylinders 2 abut against each other, the axial splicing mechanism on them automatically completes the locking connection of the adjacent support cylinders 2 under the vertical pressure drive.

[0030] Positioning channels are provided on both sides of the inner wall of the support cylinder 1. The positioning channels include a first positioning groove 5, a transition groove 6, and a second positioning groove 7. The size of the transition groove 6 is adapted to the size of the upper connecting seat 3 and the lower connecting seat 4 after splicing. The first positioning groove 5 is opened vertically on the upper part of the inner wall of the support cylinder 1, the transition groove 6 is opened horizontally on the middle part of the inner wall of the support cylinder 1, and the second positioning groove 7 is opened vertically on the lower part of the inner wall of the support cylinder 1. The first positioning groove 5 and the second positioning groove 7 are respectively connected to the two sides of the transition groove 6. The lower connecting seat 4 of the first section of the support cylinder 2 descends vertically along the first positioning groove 5, rotates into the transition groove 6, and then sinks to the end of the second positioning groove 7. At this time, the upper connecting seat 3 is simultaneously mounted on the transition groove 6. After the subsequent cylinder body is lowered and axial splicing is triggered, the positioning channel guidance process is repeated to form a continuous support cylinder 2 column extending downward from the support cylinder 1.

[0031] In this embodiment, a ring frame 8 is rotatably embedded inside the support cylinder 1, and a gear ring 9 is sleeved on the outer wall of the ring frame 8. A motor 10 is provided at the top of the support cylinder 1. The output shaft of the motor 10 extends through into the support cylinder 1 and its end is provided with a gear that meshes with the gear ring 9. Each side wall of the first positioning groove 5 is provided with a receiving groove 11. A through groove 12 is horizontally provided in the middle of the transition groove 6. The inner end face of the through groove 12 extends to communicate with the inner wall of the ring frame 8. One end of the through groove 12 extends to communicate with the corresponding receiving groove 11. Supports 13 are provided on both the front and rear sides of the inner wall of the ring frame 8. The other end of the support 13 passes through the through groove 12 and its end is provided with an arc-shaped push plate 14. The arc-shaped push plate 14 can move from the receiving groove 11 to the second positioning groove 7 under the drive of the ring frame 8.

[0032] The ring frame 8 is driven to rotate by the motor 10, which drives the arc-shaped push plate 14 at the end of the support 13 to move horizontally. After the upper connecting seat 3 and the lower connecting seat 4 are spliced ​​at the first positioning groove 5, they need to sink from the second positioning groove 7 through the transition groove 6. This switching process is driven by the arc-shaped push plate 14. The arc surface of the push plate contacts the side wall of the spliced ​​upper connecting seat 3 and the lower connecting seat 4, applying a horizontal thrust. The push plate continues to push it to move horizontally along the transition groove 6 until the connecting seat enters the second positioning groove 7. During the time when the lower connecting seat 4 of the support cylinder 2 continues to descend along the second positioning groove 7, but the upper connecting seat 3 has not yet entered the first positioning groove 5, the ring part rotates in the opposite direction, driving the arc-shaped push plate 14 to quickly reset into the storage groove 11.

[0033] In this embodiment, guide blocks 15 are provided on both the left and right sides of the top of the support cylinder 1. The guide blocks 15 have guide grooves 16 that are adapted to the upper connecting seat 3 and the lower connecting seat 4 on their inner sides. The guide grooves 16 are connected to the first positioning groove 5. The structure of the guide grooves 16 is a progressively contracting shape from top to bottom.

[0034] The opening width at the top of the guide groove 16 allows the support cylinder 2 to be inserted within a tilt range of ±15°, accommodating the initial positioning error of the construction machinery; the narrowing of the guide groove 16 from top to bottom gradually corrects the posture of the support cylinder 2 through physical constraints.

[0035] In this embodiment, the axial splicing mechanism includes a connecting block 17 and locking blocks 18 disposed on both sides of the connecting block 17. Grooves 19 are provided on both sides of the bottom of the connecting block 17. The locking blocks 18 are slidably assembled in the corresponding grooves 19, and a spring 20 is connected between the inner end of the locking block 18 and the groove 19. The top of the upper connecting seat 3 is provided with a connecting port 21 that matches the connecting block 17. The left and right sides of the inner wall of the connecting port 21 are provided with locking holes 22 that match the locking blocks 18. A plurality of sliding rods 23 are provided in the lower connecting seat 4. The connecting block 17 is slidably assembled in the lower connecting seat 4 through the sliding rods 23. A first lead screw 24 is rotatably disposed in the middle of the lower connecting seat 4. The first lead screw 24 is threadedly connected to the connecting block 17. A first slot is provided on the outer end face of the lower connecting seat 4. A first knob 25 is rotatably disposed in the first slot. The rotating shaft of the first knob 25 extends through and is connected to the first lead screw 24 through a bevel gear transmission.

[0036] When the upper and lower support cylinders 2 come into contact, the connecting block 17 of the lower connecting seat 4 is inserted into the connecting port 21 of the upper connecting seat 3, and the locking block 18 is squeezed and compressed into the groove 19. After reaching the position of the locking hole 22, the spring 20 pops out the locking block 18, completing the mechanical interlock. At the same time, the torque is transmitted by rotating the first knob 25 to drive the bevel gear set to rotate the first lead screw 24, so that the connecting block 17 slides inward along the slide rod 23 until the connecting block 17 is completely retracted into the lower connecting seat 4. After the connecting block 17 is retracted, the outer surface of the lower connecting seat 4 forms a complete plane, which avoids the deformation of the connecting block 17 due to collision during transportation. At the same time, the lower connecting seat 4 of the lowest support cylinder 2 does not need to be connected to the adjacent support cylinder 2. The retraction of the connecting block 17 can avoid hard contact with the bottom rock and soil layer, prevent the cutting edge of the locking block 18 from chipping or the guide from shifting. After the retraction, the bottom surface of the lower connecting seat 4 forms a complete streamlined structure, which reduces the resistance of silt disturbance during sinking and improves the settlement efficiency.

[0037] Unlocking blocks 26 are slidably fitted in the two side holes 22. A bidirectional lead screw 27 is rotatably installed at the bottom of the connection port. The two unlocking blocks 26 are threadedly connected to the two sides of the bidirectional lead screw 27 respectively. A second slot is opened on the outer end face of the upper connecting seat 3. A second knob 28 is rotatably installed in the second slot. The rotating shaft of the second knob 28 extends through and is connected to the bidirectional lead screw 27 through bevel gear transmission.

[0038] When the support cylinder 2 needs to be disassembled, simply turn the second knob 28, and the two-way screw 27 will drive the unlocking blocks 26 on both sides to move inward synchronously. The inward movement of the unlocking blocks 26 will squeeze the locking block 18, causing the locking block 18 to retract into the groove 19. At this time, the connecting block 17 can be pulled out from the connecting port 21.

[0039] In this embodiment, a first adjustment groove is formed in the area from the bottom end of the first positioning groove 5 to the bottom end of the support cylinder 1, and the first adjustment groove is connected to the first positioning groove 5; a second adjustment groove is formed in the area from the top end of the second positioning groove 7 to the top end of the support cylinder 1, and the second adjustment groove is connected to the second positioning groove 7; a first adjustment plate 29 is slidably embedded in the first adjustment groove, and a first airbag is connected between the first adjustment groove and the first adjustment plate 29; a second adjustment plate 30 is slidably embedded in the second adjustment groove, and a second airbag is connected between the second adjustment groove and the second adjustment plate 30; an air pipe 31 is provided at the top end of the support cylinder 1, and a control valve 32 is provided on the air pipe 31; the other end of the air pipe 31 is connected to each of the first airbags and the second airbags through several branch pipes; the bottom of the first adjustment plate 29 and the second adjustment plate 30 are both inclined structures.

[0040] After the concrete pouring of the bored pile is completed, the support casing 2 needs to be pulled out before initial setting. When the support casing 2 needs to be lifted, the air pipe 31 is opened through the control valve 32. During the lifting process of the support casing 2, the upper connecting seat 3 or the lower connecting seat 4 will contact the bottom slope of the first adjusting plate 29 or the second adjusting plate 30, pushing the first adjusting plate 29 or the second adjusting plate 30 to slide inward into the first adjusting groove or the second adjusting groove; so that the gas in the first air bag and the second air bag is vented outward; when the first adjusting plate 29 and the second adjusting plate 30 move inward, they will make way for the vertical channel of the first positioning groove 5 and the second positioning groove 7, completely removing the mechanical obstruction between the connecting seat and the support casing 1, ensuring that the support casing 2 is lifted without resistance, so that the support casing 2 does not need to rotate and move in the opposite direction according to the steps during settlement when it is lifted, and can be lifted directly;

[0041] When the support cylinder 1 is installed in another pile hole to continue working, it is only necessary to connect the air pipe 31 through the air pump and inject compressed air into the air pipe 31. The airbag pushes the first adjusting plate 29 and the second adjusting plate 30 to extend outward. The protruding first adjusting plate 29 continues to bear the load for the upper connecting seat 3 that descends from the first positioning groove 5, ensuring that the support cylinder 2 can be hung on the support cylinder 1. The protruding second adjusting plate 30 can limit the second positioning groove 7 and prevent the lower connecting seat 4 that has settled into the second positioning groove 7 from floating back due to the reaction force of the silt.

[0042] In this embodiment, both the top of the upper connecting seat 3 and the bottom of the lower connecting seat 4 are provided with mud guiding slopes, and both the left and right ends of the mud guiding slopes of the lower connecting seat 4 are provided with chamfered structures orthogonal to the rotation direction of the support cylinder 2; when the support cylinder 2 is lifted, the mud guiding slopes will guide the attached silt outwards and slide it down; when the support cylinder 2 sinks, the slopes compress the silt in front to form a fluid stripping layer, and the chamfered structure enhances the mud discharge efficiency under rotation, thereby preventing the support cylinder 2 from moving and damaging the inner wall of the pile hole.

[0043] In this embodiment, a sealing edge 33 is provided at the top of the support cylinder 2. The sealing edge 33 is located inside the upper connecting seat 3. A sealing groove that matches the sealing edge 33 is provided at the bottom of the support cylinder 2. The sealing groove at the bottom of the support cylinder 2 and the sealing edge 33 at the top of the upper support cylinder 2 are spliced ​​together to form a physical fit and seal, which can prevent leakage of the subsequently poured concrete and also prevent concrete from entering between the upper connecting seat 3 and the lower connecting seat 4 and solidifying, ensuring that the upper connecting seat 3 and the lower connecting seat 4 can be easily separated.

[0044] The working principle of this embodiment is as follows:

[0045] After the drilling and mud removal of the cast-in-place piles are completed, the support cylinder 1 is fixed at the pile hole opening as a reference platform. Its built-in three-level positioning channels (first positioning groove 5 → transition groove 6 → second positioning groove 7) constitute a precision guiding system for the settlement of the support cylinder 2. After the first section of the support cylinder 2 is inserted into the support cylinder 1, the lower connecting seat 4 descends vertically along the first positioning groove 5, rotates 90° to enter the horizontal transition groove 6, and then settles twice along the second positioning groove 7 to the target depth, forming the initial support point with spatial misalignment.

[0046] The subsequent support cylinder 2 is automatically connected through an axial splicing mechanism: when the new support cylinder 2 is lowered, the connecting block 17 of its lower connecting seat 4 is inserted into the locking hole 22 of the upper connecting seat 3 of the installed cylinder, and the spring 20 drives the locking block 18 to pop out to complete the mechanical interlock; after locking, the cylinder repeats the process of "vertical descent → rotation → secondary settlement", and extends section by section to the bottom of the pile hole under the guidance of the support cylinder 1 to form a continuous support column, so as to splice and settle the corresponding number of support cylinders 2 according to the design depth.

[0047] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A protective device for rotary-drilled cast-in-place piles in silt areas, characterized in that: It includes a support cylinder and several support cylinders. The support cylinder is used to be installed at the pile opening at the upper end of the pile hole. The upper left and right sides of the upper end of the support cylinder are provided with upper connecting seats, and the lower front and rear sides of the lower end of the support cylinder are provided with lower connecting seats. The lower connecting seats are provided with axial splicing mechanisms corresponding to the upper connecting seats. When two adjacent support cylinders abut each other, the axial splicing mechanisms on them automatically complete the locking connection of the adjacent support cylinders under the vertical pressure drive. Positioning channels are provided on both sides of the inner wall of the support cylinder. The positioning channels include a first positioning groove, a transition groove, and a second positioning groove. The size of the transition groove is adapted to the size of the upper connecting seat and the lower connecting seat after splicing. The first positioning groove is opened vertically on the upper part of the inner wall of the support cylinder, the transition groove is opened horizontally on the middle part of the inner wall of the support cylinder, and the second positioning groove is opened vertically on the lower part of the inner wall of the support cylinder. The first positioning groove and the second positioning groove are respectively connected to the two sides of the transition groove. The lower connecting seat of the first support cylinder descends vertically along the first positioning groove, rotates into the transition groove, and then sinks down to the end of the second positioning groove. At this time, the upper connecting seat is simultaneously mounted on the transition groove. After the subsequent cylinder is lowered and axial splicing is triggered, the positioning channel guidance process is repeated to form a continuous support cylinder column extending downward from the support cylinder.

2. The protective device for rotary drilling piles in silt areas according to claim 1, characterized in that: A ring frame is rotatably embedded inside the support cylinder. A gear ring is fitted on the outer wall of the ring frame. A motor is installed at the top of the support cylinder. The output shaft of the motor extends through the support cylinder and has a gear at its end that meshes with the gear ring. Each of the first positioning slots has a receiving slot on its side wall. A through slot is horizontally opened in the middle of the transition slot. The inner end face of the through slot extends to communicate with the inner wall of the ring frame. One end of the through slot extends to communicate with the corresponding receiving slot. Supports are provided on both the front and rear sides of the inner wall of the ring frame. The other end of the support passes through the through slot and has an arc-shaped push plate at its end. The arc-shaped push plate can move from the receiving slot to the second positioning slot under the drive of the ring frame, thereby pushing the lower connecting seat of the support cylinder to move horizontally, so that it can accurately transition from the first positioning slot to the second positioning slot, realizing the automated switching of the settlement path of the support cylinder.

3. The protective device for rotary drilling piles in silt areas according to claim 1, characterized in that: Guide blocks are provided on both the left and right sides of the top of the support cylinder. The guide blocks have guide grooves on their inner sides that are adapted to the upper and lower connecting seats. The guide grooves are connected to the first positioning grooves. The structure of the guide grooves is a progressively contracting shape from top to bottom.

4. The protective device for rotary drilling piles in silt areas according to claim 1, characterized in that: The axial splicing mechanism includes a connecting block and locking blocks disposed on both sides of the connecting block. Grooves are provided on both bottom sides of the connecting block, and the locking blocks are slidably fitted into the corresponding grooves. A spring connects the inner end of the locking block to the groove. A connecting port adapted to the connecting block is provided at the top of the upper connecting seat, and locking holes adapted to the locking blocks are provided on both the left and right sides of the inner wall of the connecting port. Several sliding rods are provided inside the lower connecting seat, and the connecting block is slidably fitted into the lower connecting seat via the sliding rods. A first lead screw is rotatably disposed in the center of the lower connecting seat, and the first lead screw is threadedly connected to the connecting block. A first slot is provided on the outer end face of the lower connecting seat, and a first knob is rotatably disposed within the first slot. The rotating shaft of the first knob extends through and is connected to the first lead screw via a bevel gear transmission.

5. A protective device for rotary drilling piles in silt areas according to claim 4, characterized in that: Unlocking blocks are slidably fitted into the card holes on both sides. A bidirectional lead screw is rotatably provided at the bottom of the connection port. The unlocking blocks on both sides are threadedly connected to the two sides of the bidirectional lead screw. A second slot is provided on the outer end face of the upper connecting seat. A second knob is rotatably provided in the second slot. The rotating shaft of the second knob extends through and is connected to the bidirectional lead screw through a bevel gear transmission.

6. A protective device for rotary drilling piles in silt areas according to claim 1, characterized in that: A first adjustment groove is formed in the area from the bottom of the first positioning groove to the bottom of the support cylinder, and the first adjustment groove is connected to the first positioning groove; a second adjustment groove is formed in the area from the top of the second positioning groove to the top of the support cylinder, and the second adjustment groove is connected to the second positioning groove; a first adjustment plate is slidably embedded in the first adjustment groove, and a first airbag is connected between the first adjustment groove and the first adjustment plate; a second adjustment plate is slidably embedded in the second adjustment groove, and a second airbag is connected between the second adjustment groove and the second adjustment plate; an air pipe is provided at the top of the support cylinder, and a control valve is provided on the air pipe; the other end of the air pipe is connected to each of the first and second airbags through several branch pipes; the bottoms of the first and second adjustment plates are both inclined structures.

7. A protective device for rotary drilling piles in silt areas according to claim 1, characterized in that: Both the top of the upper connecting seat and the bottom of the lower connecting seat are provided with mud guiding slopes, and both the left and right ends of the mud guiding slope of the lower connecting seat are provided with chamfer structures orthogonal to the rotation direction of the support cylinder.

8. A protective device for rotary drilling piles in silt areas according to claim 1, characterized in that: The top of the support cylinder is provided with a sealing edge, which is located inside the upper connecting seat. The bottom of the support cylinder is provided with a sealing groove that matches the sealing edge.

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