Rotary excavating cast-in-place pile construction system for reducing diffusion of karst cave concrete

Abstract

The invention discloses a rotary excavating cast-in-place pile construction system for reducing karst cave concrete diffusion, which comprises a karst cave concrete anti-diffusion device and a construction method, the karst cave concrete anti-diffusion device is adopted in the construction method, and the karst cave concrete anti-diffusion device comprises a reinforcement cage, a waterproof pipe, a mold protection device, a first limiting ring and a second limiting ring; the mold protection device comprises a steel protection pipe, a valve pipe and a pushing mechanism. The method comprises the steps that the mold protection device enters the pile hole, the reinforcement cage enters the valve pipe, the cast-in-place pile is integrally poured, and the bottom bearing platform and the top bearing platform are poured. Overall pouring of the cast-in-place pile in the karst cave area can be achieved, the forming quality of the cast-in-place pile is fully guaranteed, the waterproof effect is improved, and the construction efficiency is improved while concrete waste is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of cast-in-place pile construction, and in particular to a rotary bored cast-in-place pile construction system for reducing the diffusion of karst cave concrete. Background Art

[0002] my country's karst area is vast. With the rapid development of my country's infrastructure projects, more and more engineering construction projects will encounter karst geological conditions, and karst caves have caused great trouble to the progress of the projects.

[0003] At present, in the process of engineering pile construction under the above geological conditions, most engineering teams usually directly drill the pile hole, and then put down the steel cage to pour concrete to form it, so that the concrete can be poured into the cave at the same time. However, since the internal space of the cave is usually large, in the actual construction process, a large amount of concrete is used to fill the cave, which greatly increases the amount of concrete used and the engineering cost is high.

[0004] The existing patent document CN117127614A provides some improvements in the construction process of rotary bored piles to reduce the diffusion of concrete in the karst cave area, which includes the following steps: S1, detecting the karst cave data at the construction site; S2, performing rotary bored pile hole shaping; S3, draining the pile hole; S4, making a steel cage, referring to the karst cave data recorded in steps S1 and S2, and setting an isolation net on the steel cage that can isolate the concrete from diffusing outward; S5, lowering the steel cage so that the isolation net is sealed in the karst cave; S6, casting and shaping the pile hole. In the process of casting and shaping the bored piles in this application, the isolation net can block the karst cave location and reduce the diffusion of concrete in the karst cave area. This saves the amount of concrete and further reduces the project cost. However, the patent document has the following defects:

[0005] (1) Bored piles need to be cast in sections, which increases the risk of broken piles, makes the concrete in the pile body easy to segregate, and significantly reduces construction efficiency.

[0006] (2) During the process of rotary drilling of the pile hole, the soil around the cave is easily loosened. Although the document tied an isolation net outside the steel cage, it is difficult to ensure that the soil at the junction of the pile hole and the cave will not collapse during the construction process, and there is still a great risk of concrete waste. Summary of the invention

[0007] The present invention provides a rotary bored pile construction system for reducing the diffusion of karst cave concrete, aiming to solve the problems described in the background technology parts (1) and (2).

[0008] To solve the above problems, the technical solution of the present invention is:

[0009] A rotary bored pile construction system for reducing the diffusion of karst concrete, comprising a karst concrete diffusion prevention device and a construction method, wherein the construction method adopts the karst concrete diffusion prevention device, the karst concrete diffusion prevention device comprising a steel cage, a waterproof pipe, and a mold protection device, wherein a first limiting ring is connected to the top of the steel cage, a second limiting ring is welded to the bottom, and a waterproof pipe is coaxially clamped between the first limiting ring and the second limiting ring and located at the outer periphery of the steel cage;

[0010] The mold protection device comprises a steel protective tube and a valve tube, wherein the valve tube is formed by connecting two or more arc-shaped plates, the inner diameter of the valve tube formed by connecting is the same as the outer diameter of the waterproof tube, the valve tube is located inside the steel protective tube, and the inner wall of the steel protective tube is provided with a push mechanism connected to the outer wall of each arc-shaped plate;

[0011] The waterproof pipe is arranged inside the valve pipe. When the pushing mechanism pushes the valve pipe into a complete pipe, the inner wall of the valve pipe fits with the outer wall of the waterproof pipe. The construction method adopts the above-mentioned karst concrete anti-diffusion device.

[0012] The steel cage comprises a plurality of longitudinal bars arranged in the longitudinal direction and evenly distributed around the axis of the steel cage, and a plurality of annular steel bars are evenly welded between the inner walls of the plurality of longitudinal bars in the height direction;

[0013] The first limiting ring is an inverted "convex" structure, and the second limiting ring is an upright "convex" structure and is coaxial with the steel cage.

[0014] Preferably, the upper end of the waterproof tube is clamped in the small diameter section of the inverted "convex" structure, and the outer wall of the waterproof tube is flush with the outer wall of the large diameter section of the inverted "convex" structure. The first limiting ring has a plurality of connecting holes evenly distributed around the axis, and the inner hole of the first limiting ring is used to pass through the first conduit for pouring concrete.

[0015] Preferably, the longitudinal reinforcements are opposite to the connecting holes one by one, the top of the longitudinal reinforcement passes through the connecting hole and is coaxially welded with an auxiliary suspension rod, the top of the outer wall of the longitudinal reinforcement is provided with an external thread, and a limit nut for limiting the position of the first limit ring is screwed thereon, and the auxiliary suspension rod is used to connect the lifting equipment.

[0016] Preferably, the top of the upright "convex" structure of the second limiting ring is welded to the bottom end of the longitudinal rib, the lower end of the waterproof tube is clamped with the small diameter section of the upright "convex" structure, and the outer surface of the waterproof tube is flush with the outer surface of the large diameter section of the upright "convex" structure.

[0017] Preferably, the waterproof tube is a rubber tube or a PVC tube or a PE tube.

[0018] Preferably, the length of the steel protective tube is the same as the height of the pile hole of the cast-in-place pile, the length of the valve tube is the same as the length of the waterproof tube, and the jacking mechanism includes one or more electrically controlled telescopic devices arranged at the upper and lower ends of the arc plate;

[0019] One end of the electric telescopic device is hinged to the inner wall of the steel protective tube, and the other end is hinged to the outer wall of the arc plate. The axis of the electric telescopic mechanism intersects with the axis of the valve tube. The inner wall of the arc plate is provided with an elastic buffer layer.

[0020] Preferably, it also includes a top base molded casing, which includes a cylinder with an open upper end, a through hole coaxially opened at the bottom of the cylinder, the inner diameter of the through hole is the same as the outer diameter of the waterproof pipe, and a plurality of embedded steel bars are radially welded on the outer wall where the top end of the cylinder is located.

[0021] Preferably, the construction method comprises the following steps:

[0022] S1. Detecting cave data at the construction location by detection equipment, wherein the cave data at least includes the location, height and span of the cave;

[0023] S2, the pile hole is formed by rotary drilling, and the lower end of the pile hole is 3 meters lower than the bottom of the karst cave at the junction of the pile hole;

[0024] S3, draining the pile hole;

[0025] S4, hoisting the mold protection device as a whole into the pile hole, so that the steel protection pipe is located at a position close to or close to the inner wall of the pile hole, and the bottom end of the steel protection pipe is against the bottom of the pile hole;

[0026] S5. Ground personnel control the electric control telescopic device to move synchronously, so that the valve tube forms a complete pipeline; then, with the cooperation of the lifting equipment, the steel cage with the waterproof pipe pre-clamped is lowered with the inner wall of the pipeline as the guide hole, so that the second limit ring contacts the bottom of the pile hole;

[0027] S6. Setting up a bracket on the ground around the pile hole, fixing the auxiliary suspension rod through the bracket, so that the steel cage maintains the existing posture; inserting the first guide tube through the inner hole of the first limit ring, and casting the cast-in-place pile as a whole. During this process, the valve tube protects the outer wall of the waterproof tube to ensure that it withstands the force of the concrete during casting;

[0028] S7. After the cast-in-place pile is formed, the electric-controlled telescopic device retracts, and the valve tube is decomposed into two or more arc-shaped plates. The arc-shaped plates move toward the side of the steel protective tube due to the retraction of the electric-controlled telescopic device. Then, the mold protection device is lifted up by the lifting equipment so that the bottom of the mold protection device is 2.5 meters away from the bottom of the pile hole;

[0029] S8, inserting a second conduit into the gap between the arc plate and the waterproof pipe, the second conduit being inserted into the annular space to be poured between the bottom of the mold protection device and the bottom of the pile hole, injecting self-compacting concrete slurry according to the capacity of the annular space to be poured, and forming the bottom cap of the cast-in-place pile after the self-compacting slurry is formed;

[0030] S9, remove the bracket, hoist out the mold protection device as a whole, open an annular groove on the outer periphery of the upper end of the pile hole, insert the molded casing at the top of the pile hole, the outer wall of the molded casing fits with the inner wall of the pile hole, the through hole and the outer wall of the waterproof pipe are matched, and the embedded steel bars are welded to the top cap steel cage in the annular groove;

[0031] S10, pour concrete into the formed casing and the annular groove to form the top cap, and cut off the auxiliary hanger at the top of the cast-in-place pile.

[0032] The rotary bored pile construction system for reducing the diffusion of karst cave concrete of the present invention has the following beneficial effects:

[0033] The present invention can realize the integral casting of bored piles in karst cave areas, fully ensure the molding quality of bored piles, improve the waterproof effect, avoid concrete waste and improve construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 , a schematic diagram of the structure of the valve tube and the waterproof tube of the present invention when they are separated;

[0035] Figure 2 , a schematic diagram of the structure of the valve tube and the waterproof tube of the present invention when they are attached together;

[0036] Figure 3 , a schematic structural diagram of the mold protection device of the present invention when the bottom is 2.5 meters away from the bottom of the pile hole;

[0037] Figure 4 , a schematic diagram of the structure of the bottom support and the top support of the present invention;

[0038] Figure 5 , a schematic diagram of the top view of the structure of the molded casing of the present invention;

[0039] Figure 6 , a schematic diagram of the top view of the structure of the mold protection device and the waterproof pipe of the present invention.

[0040] Figure 7 , a front view structural schematic diagram of the first limiting ring of the present invention.

[0041] Figure 8 , a schematic diagram of the top view of the structure of the first limiting ring of the present invention.

[0042] Fig. 9 , a schematic diagram of the structure of the second limiting ring of the present invention cooperating with the bottom of the waterproof pipe.

[0043] 1: cave, 2: pile hole, 3: steel cage, 31. longitudinal reinforcement; 32. auxiliary hanger; 4: soil, 5. steel protective pipe; 6. valve tube; 61. arc plate; 7. waterproof pipe; 8. jacking mechanism; 9. second limiting ring; 10. first limiting ring; 101. small diameter section of inverted "convex" structure; 102. connecting hole; 103. inner hole of the first limiting ring; 11: limiting nut, 12: bracket, 13: annular space to be poured, 14: gap between valve plate and waterproof pipe, 15: bottom pedestal, 16: formed casing, 17: embedded steel bars, 18: top pedestal, 19: concrete. DETAILED DESCRIPTION

[0044] The following describes in detail the implementation mode of the present invention in a step-by-step manner. The description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0045] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the purpose of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, and a specific direction structure and operation, and therefore cannot be understood as a limitation on the present invention.

[0046] Example 1

[0047] In the initial embodiment, the present invention is a rotary bored pile construction system for reducing the diffusion of karst concrete, such as Figure 1-9 As shown, it includes a karst cave concrete anti-diffusion device and a construction method. The karst cave concrete anti-diffusion device includes a steel cage 3, a waterproof pipe 7, and a mold protection device. The top of the steel cage 3 is connected to a first limiting ring 10, and the bottom is welded with a second limiting ring 9. Between the first limiting ring 10 and the second limiting ring 9 and located at the outer periphery of the steel cage 3, a waterproof pipe 7 is coaxially clamped.

[0048] The mold protection device includes a steel protective tube 5 and a valve tube 6. The valve tube 6 is formed by connecting two or more arc plates 61. The inner diameter of the connected valve tube 6 is the same as the outer diameter of the waterproof tube 7. The valve tube 6 is located inside the steel protective tube 5. The inner wall of the steel protective tube 5 is provided with a pushing mechanism 8 connected to the outer wall of each arc plate 61. The waterproof tube 7 is arranged on the inner side of the valve tube 6. Figure 6 As shown, when the pushing mechanism 8 pushes the valve tube 6 to form a complete pipe, the inner wall of the valve tube 6 fits with the outer wall of the waterproof tube 7.

[0049] In this embodiment, the mold protection device protects the inner wall of the pile hole on the one hand, and protects the waterproof tube by driving the valve tube to form on the other hand, effectively preventing the waterproof tube from rupturing during the pouring process, and then assisting the bored pile to be formed in one time through overall pouring, avoiding the quality risks brought by segmented pouring.

[0050] By setting up the waterproof pipe, on the one hand, the bored pile can have a good waterproof function, so that the bored pile can adapt to the special geological conditions of the karst cave area. At the same time, the waterproof pipe retains the distance between it and the steel cage through the constraints of the first limiting ring and the second limiting ring, which is suitable for the precise forming of the steel protection layer.

[0051] Example 2

[0052] In a further embodiment, Figure 1-9 As shown, the first limiting ring 10 is an inverted "convex" structure, the upper end of the waterproof tube 7 is clamped in the small diameter section 101 of the inverted "convex" structure, the outer wall of the waterproof tube 7 is flush with the outer wall of the large diameter section of the inverted "convex" structure, and the first limiting ring 10 is evenly distributed with a plurality of connecting holes 102 around the axis, and the inner hole 103 of the first limiting ring is used to pass through the first conduit for pouring concrete.

[0053] like Figure 1-9 As shown, the steel cage 3 includes a plurality of longitudinal bars 31 which are arranged longitudinally and evenly distributed around the axis of the steel cage, a plurality of annular steel bars (hoops) are evenly welded between the inner walls of the plurality of longitudinal bars 31 along the height direction, the longitudinal bars 31 are opposite to the connecting holes 102 one by one, the top of the longitudinal bars 31 passes through the connecting holes 102 and is coaxially welded with an auxiliary suspension rod 32, the top of the outer wall of the longitudinal bars 31 is provided with an external thread, and a limiting nut 11 for limiting the position of the first limiting ring 10 is screwed, and the auxiliary suspension rod 32 is used to connect the lifting equipment.

[0054] Example 3

[0055] In a further embodiment, Figure 1-9 As shown, the second limiting ring 9 is a positive "convex" structure and is coaxial with the steel cage 3. The top of the positive "convex" structure is welded to the bottom end of the longitudinal reinforcement 31, and the lower end of the waterproof tube 7 is clamped with the small diameter section of the positive "convex" structure (such as Fig. 9 As shown in FIG. 1 , the outer surface of the waterproof tube 7 is flush with the outer surface of the large diameter section of the upright "convex" structure. The waterproof tube 7 is a rubber tube or a PVC tube or a PE tube.

[0056] like Figure 1-9As shown, the length of the steel protective tube 5 is the same as the height of the pile hole 2 of the bored pile, the length of the valve tube 6 is the same as the length of the waterproof tube 7, and the pushing mechanism 8 includes one or more electrically controlled telescopic devices, such as electric push rods, cylinders, and hydraulic cylinders, arranged at the upper and lower ends of the arc plate. One end of the electrically controlled telescopic device is hinged to the inner wall of the steel protective tube 5, and the other end is hinged to the outer wall of the arc plate 61. The axis of the electrically controlled telescopic mechanism intersects with the axis of the valve tube 6, that is, both are pushed in the direction of the axis of the valve tube to prevent deviation. The inner wall of the arc plate 61 is provided with an elastic buffer layer to fit the waterproof tube tightly.

[0057] In a further embodiment, Figure 1-9 As shown, it also includes a top support 18 forming casing 16, the forming casing 16 includes a cylinder with an open upper end, and a through hole is coaxially opened at the bottom of the cylinder, such as Figure 5 As shown, the inner diameter of the through hole is the same as the outer diameter of the waterproof pipe 7, and a plurality of embedded steel bars 17 are radially welded on the outer wall where the top end of the cylinder is located.

[0058] Example 4

[0059] Based on the above embodiments, this embodiment discloses a construction method of a karst cave concrete diffusion prevention device, such as Figure 1-9 As shown, the following steps are included:

[0060] S1. Detecting cave data at the construction location by detection equipment, wherein the cave data at least includes the location, height and span of cave 1;

[0061] S2, the pile hole 2 is formed by rotary drilling, and the lower end of the pile hole 2 is 3 meters lower than the bottom of the cave 1 bordering the pile hole;

[0062] S3, draining the pile hole 2;

[0063] S4, hoist the mold protection device as a whole into the pile hole 2, so that the steel protection pipe 5 is located in a position close to or close to the inner wall of the pile hole 2, and the bottom end of the steel protection pipe 5 is against the bottom of the pile hole 2;

[0064] S5, such as Figure 2 As shown, the ground personnel control the electric control telescopic device to move synchronously, so that the valve tube 6 forms a complete pipeline; then, with the cooperation of the lifting equipment, the steel cage 3 with the waterproof tube 7 pre-clamped is lowered with the inner wall of the pipeline as the guide hole, so that the second limit ring 9 contacts the bottom of the pile hole 2;

[0065] S6, such as Figure 2As shown, a bracket 12 is set up on the ground around the pile hole 2, and the auxiliary suspension rod 32 is fixed by the bracket 12 to keep the steel cage 3 in the existing posture; the first guide tube is inserted through the inner hole 103 of the first limiting ring to cast the cast-in-place pile as a whole. During this process, the valve tube 6 protects the outer wall of the waterproof tube 7 to ensure that it withstands the force of the concrete during casting;

[0066] S7, such as Figure 3 As shown, after the cast-in-place pile is formed, the electric-controlled telescopic device retracts, and the valve tube 6 is decomposed into two or more arc-shaped plates 61. The arc-shaped plates 61 move toward the side of the steel protective tube 5 due to the retraction of the electric-controlled telescopic device. Then, the mold protection device is lifted upward by the lifting equipment so that the bottom of the mold protection device is 2.5 meters away from the bottom of the pile hole.

[0067] S8, inserting a second conduit into the gap between the arc plate 61 and the waterproof pipe 7, the second conduit is inserted into the annular space 13 to be poured between the bottom of the mold protection device and the bottom of the pile hole, injecting self-compacting concrete slurry according to the capacity of the annular space 13 to be poured, and the self-compacting slurry is formed to form the bottom cap 15 of the cast-in-place pile;

[0068] S9, remove the bracket 12, hoist out the mold protection device as a whole, open an annular groove on the outer periphery of the upper port of the pile hole 2, insert the molded casing 16 at the top of the pile hole, the outer wall of the molded casing 16 is fitted with the inner wall of the pile hole 2, the through hole and the outer wall of the waterproof pipe 7 are matched, and the embedded steel bar 17 is welded to the top cap 18 steel cage in the annular groove;

[0069] S10, pouring concrete 19 into the forming casing 16 and the annular groove to form the top cap 18, and cutting off the auxiliary suspension rod 32 at the top of the cast-in-place pile.

Claims

1. A rotary bored pile construction system for reducing the diffusion of karst concrete, characterized by: It includes a karst cave concrete anti-diffusion device and a construction method. The construction method adopts the karst cave concrete anti-diffusion device. The karst cave concrete anti-diffusion device includes a steel cage, a waterproof pipe, and a mold protection device. The top of the steel cage is connected with a first limiting ring, the bottom is welded with a second limiting ring, and a waterproof pipe is coaxially clamped between the first limiting ring and the second limiting ring and located at the outer periphery of the steel cage. The mold protection device comprises a steel protective tube and a valve tube, wherein the valve tube is formed by connecting two or more arc-shaped plates, the inner diameter of the valve tube formed by connecting is the same as the outer diameter of the waterproof tube, the valve tube is located inside the steel protective tube, and the inner wall of the steel protective tube is provided with a push mechanism connected to the outer wall of each arc-shaped plate; The waterproof pipe is arranged inside the valve pipe. When the pushing mechanism pushes the valve pipe into a complete pipe, the inner wall of the valve pipe fits with the outer wall of the waterproof pipe. The construction method adopts the above-mentioned karst concrete anti-diffusion device. The steel cage comprises a plurality of longitudinal bars arranged in the longitudinal direction and evenly distributed around the axis of the steel cage, and a plurality of annular steel bars are evenly welded between the inner walls of the plurality of longitudinal bars in the height direction; The first limiting ring is an inverted "convex" structure, and the second limiting ring is an upright "convex" structure and is coaxial with the steel cage.

2. A rotary bored pile construction system for reducing the diffusion of karst concrete as claimed in claim 1, characterized in that: The upper end of the waterproof pipe is clamped on the small diameter section of the inverted "convex" structure, and the outer wall of the waterproof pipe is flush with the outer wall of the large diameter section of the inverted "convex" structure. The first limiting ring is provided with a plurality of connecting holes evenly distributed around the axis, and the inner hole of the first limiting ring is used to pass through the first conduit for pouring concrete.

3. A rotary bored pile construction system for reducing the diffusion of karst concrete as claimed in claim 2, characterized in that: The longitudinal reinforcements are opposite to the connecting holes one by one, the top of the longitudinal reinforcements passes through the connecting holes and is coaxially welded with an auxiliary suspension rod, the top of the outer wall of the longitudinal reinforcements is provided with an external thread and is screwed with a limit nut for limiting the position of the first limit ring, and the auxiliary suspension rod is used to connect the lifting equipment.

4. A rotary bored pile construction system for reducing the diffusion of karst concrete as claimed in claim 3, characterized in that: The top of the upright "convex" structure of the second limiting ring is welded to the bottom end of the longitudinal rib, the lower end of the waterproof tube is clamped with the small diameter section of the upright "convex" structure, and the outer surface of the waterproof tube is flush with the outer surface of the large diameter section of the upright "convex" structure.

5. A rotary bored pile construction system for reducing the diffusion of karst cave concrete as claimed in claim 4, characterized in that: The waterproof tube is a rubber tube, a PVC tube or a PE tube.

6. A rotary bored pile construction system for reducing the diffusion of karst concrete as claimed in claim 5, characterized in that: The length of the steel protective pipe is the same as the height of the pile hole of the cast-in-place pile, the length of the valve pipe is the same as the length of the waterproof pipe, and the jacking mechanism includes one or more electrically controlled telescopic devices arranged at the upper and lower ends of the arc plate; One end of the electric telescopic device is hinged to the inner wall of the steel protective tube, and the other end is hinged to the outer wall of the arc plate. The axis of the electric telescopic mechanism intersects with the axis of the valve tube. The inner wall of the arc plate is provided with an elastic buffer layer.

7. A rotary bored pile construction system for reducing the diffusion of karst concrete as claimed in claim 6, characterized in that: It also includes a top base forming casing, which includes a cylinder with an open upper end and a through hole coaxially opened at the bottom of the cylinder. The inner diameter of the through hole is the same as the outer diameter of the waterproof pipe, and a plurality of embedded steel bars are radially welded on the outer wall where the top end of the cylinder is located.

8. A rotary bored pile construction system for reducing the diffusion of karst cave concrete as claimed in claim 7, characterized in that: The construction method includes the following steps: S1. Detecting cave data at the construction location by detection equipment, wherein the cave data at least includes the location, height and span of the cave; S2, the pile hole is formed by rotary drilling, and the lower end of the pile hole is 3 meters lower than the bottom of the karst cave at the junction of the pile hole; S3, draining the pile hole; S4, hoisting the mold protection device as a whole into the pile hole, so that the steel protection pipe is located at a position close to or close to the inner wall of the pile hole, and the bottom end of the steel protection pipe is against the bottom of the pile hole; S5. Ground personnel control the electric control telescopic device to move synchronously, so that the valve tube forms a complete pipeline; then, with the cooperation of the lifting equipment, the steel cage with the waterproof pipe pre-clamped is lowered with the inner wall of the pipeline as the guide hole, so that the second limit ring contacts the bottom of the pile hole; S6. Setting up a bracket on the ground around the pile hole, fixing the auxiliary suspension rod through the bracket, so that the steel cage maintains the existing posture; inserting the first guide tube through the inner hole of the first limit ring, and casting the cast-in-place pile as a whole. During this process, the valve tube protects the outer wall of the waterproof tube to ensure that it withstands the force of the concrete during casting; S7. After the cast-in-place pile is formed, the electric-controlled telescopic device retracts, and the valve tube is decomposed into two or more arc-shaped plates. The arc-shaped plates move toward the side of the steel protective tube due to the retraction of the electric-controlled telescopic device. Then, the mold protection device is lifted up by the lifting equipment so that the bottom of the mold protection device is 2.5 meters away from the bottom of the pile hole; S8, inserting a second conduit into the gap between the arc plate and the waterproof pipe, the second conduit being inserted into the annular space to be poured between the bottom of the mold protection device and the bottom of the pile hole, injecting self-compacting concrete slurry according to the capacity of the annular space to be poured, and forming the bottom cap of the cast-in-place pile after the self-compacting slurry is formed; S9, remove the bracket, hoist out the mold protection device as a whole, open an annular groove on the outer periphery of the upper end of the pile hole, insert the molded casing at the top of the pile hole, the outer wall of the molded casing fits with the inner wall of the pile hole, the through hole and the outer wall of the waterproof pipe are matched, and the embedded steel bars are welded to the top cap steel cage in the annular groove; S10, pour concrete into the formed casing and the annular groove to form the top cap, and cut off the auxiliary hanger at the top of the cast-in-place pile.

Images