Pile casing for cast-in-situ bored pile of foundation pit

Abstract

The invention discloses a pile casing for a cast-in-situ bored pile of a foundation pit, and relates to the technical field of building foundation equipment. Comprising a plurality of supporting frames arranged on the inner side of a pile casing body, each supporting frame comprises a center block located in the center, a plurality of supporting rods distributed at equal intervals are connected to the outer side of each center block, sliding rods are fixed to the supporting rods, moving rods are arranged at the other ends of the sliding rods, sliding holes are formed in the moving rods, and arc-shaped supporting rods are fixed to the ends of the outer sides of the moving rods. The pile casing main body is supported from the inner side through the multiple supporting frames, deformation of the pile casing main body is prevented, after the supporting frames move upwards and break away from the vertical sliding rails, limiting on the sliding rods and the movable rods is relieved through the limiting mechanisms, the movable rods move in the direction close to the center block along the sliding rods, and the pile casing main body is prevented from being deformed. And then the supporting frame can be taken out from the upper end of the pile casing main body, so that the strength of the pile casing can be improved, the supporting frame can be reused in other pile casings, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of construction foundation equipment, and specifically relates to a casing for bored cast-in-place piles in foundation pits. Background Art

[0002] The casing is a key device used in the construction of bored cast-in-place piles to fix the pile position, protect the hole opening, and maintain the stability of the hole wall. It is usually made of steel or reinforced concrete, and forms a closed guiding structure by being buried on the ground or underwater. Its core functions include: isolating surface water and sundries to prevent the hole opening from collapsing, maintaining the mud level in the hole to balance the lateral pressure of the soil mass, guiding the drill bit to drill vertically and reducing the hole deviation. In complex geological conditions (such as soft soil, quicksand layer) or deep-water operations, the casing needs to be deeply buried or spliced and designed to penetrate into the stable soil layer. Its diameter is usually 20 cm - 40 cm larger than the pile diameter, and the wall thickness is determined according to the geological load (4 mm - 12 mm for steel casing, 8 cm - 10 cm for reinforced concrete casing). During the construction process, the perpendicularity deviation (≤1%) and the splicing tightness need to be strictly controlled to ensure the construction quality and structural safety of the pile foundation.

[0003] The structural strength of the casing is crucial. For example, a casing for bored cast-in-place piles in foundation pits disclosed in the patent publication number CN219080300U includes a body, and a support frame is arranged inside the body. The support frame includes a main support rod that fits the inner wall of the body, and a number of extended sub-skeletons are symmetrically arranged on the main support rod, and the extended sub-skeletons fit the inner wall of the body. For the casing for bored cast-in-place piles in foundation pits provided by this utility model, when the body needs to be taken out during the pouring of concrete, the hook of the crane is hooked on the pulling ring, and then pulled. At this time, the extended sub-skeletons can play a good supporting role to avoid the body being deformed by the pulling force, can maintain a cylindrical shape to reduce the damage to the soil surface, and can also facilitate the removal of the body. It is also provided with a hammering ring and a cutting edge, and the cutting edge can be squeezed into the soil by hammering the hammering ring during the installation of the body, which is convenient for installation and reduces the damage to the body.

[0004] Although the above-mentioned casing provides a strengthening structure, due to the limitation of the casing wall thickness, the strengthening effect is limited. When the casing penetrates deep into the ground, hammering and vibration need to be provided from above. The part deep into the ground is supported by the soil and is not easily deformed, but there is no support on both the inner and outer sides of the part above the ground. Especially when the casing is relatively long, it is prone to deformation during the hammering process. Summary of the Invention

[0005] The purpose of the present invention is to provide a casing for bored cast-in-place piles in foundation pits to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A casing pipe for a bored cast-in-place pile in a foundation pit, comprising a casing pipe main body. A hammering sleeve is arranged at the upper end of the casing pipe main body, and the hammering sleeve covers the upper edge of the casing pipe main body. A cutting inlet is arranged at the lower end of the casing pipe main body. A plurality of vertically distributed and circumferentially evenly arranged vertical sliding rails are fixed on the inner wall of the casing pipe main body, and pointed ends are arranged at the lower ends of the vertical sliding rails. A plurality of support frames are arranged inside the casing pipe main body, and the support frames are evenly distributed up and down at equal intervals inside the casing pipe main body. The support frame includes a central block located at the central position. A plurality of evenly distributed support rods are connected to the outside of the central block, and sliding rods are fixed on the support rods. The other ends of the sliding rods are provided with moving rods. Slide holes are formed in the moving rods, and the sliding rods are slidably inserted into the slide holes. A limiting mechanism is further arranged on the moving rod for limiting the sliding of the sliding rod. An arc-shaped support rod is fixed at the outer end of the moving rod. A chute is formed in the middle position of the arc-shaped support rod, and the arc-shaped support rod is slidably arranged on the vertical sliding rail through the chute.

[0007] Preferably, the limiting mechanism includes a sliding sleeve slidably arranged on the outside of the moving rod. A top rod is fixed on the outside of the sliding sleeve. One end of the top rod abuts against the vertical sliding rail, and an inclined surface is arranged at the end of the top rod close to the vertical sliding rail. Two symmetrically distributed round holes are formed in the sliding sleeve. Limiting blocks are slidably arranged in the round holes. One end of the limiting block close to the slide hole is hemispherical, and the other end is an inclined surface. The hemispherical end of the limiting block abuts against the end of the sliding rod. Two triangular grooves with inclined bottoms are formed on the inner surface of the sliding sleeve, and the inclined surface of the limiting block abuts against the bottom of the triangular groove. A tension spring is arranged in the slide hole, and the two ends of the tension spring are respectively fixed to the bottom of the slide hole and the sliding rod.

[0008] Preferably, a fixing sleeve is fixed at the end of the sliding rod inside the slide hole, and the fixing sleeve is sleeved on the outside of the tension spring. The outside of the fixing sleeve abuts against the limiting block. An extension sleeve is arranged at one end of the sliding sleeve close to the central block, and the extension sleeve is sleeved on the outside of the support rod.

[0009] Preferably, a plurality of first annular grooves are evenly distributed on the outside of the moving rod, and first sealing rings are sleeved in the first annular grooves. The outside of the first sealing rings abuts against the inner wall of the sliding sleeve. A plurality of second annular grooves are evenly distributed on the outside of the support rod, and second sealing rings are sleeved in the second annular grooves. The outside of the second sealing rings abuts against the inner wall of the extension sleeve.

[0010] Preferably, a plurality of evenly distributed connecting rods are fixed on the central block. The support rods are respectively connected to the corresponding connecting rods. First half-width plates are arranged on the support rods, and second half-width plates are arranged on the connecting rods. The first half-width plates and the second half-width plates are detachably connected by a plurality of fixing bolts. Support connecting rods are arranged between both sides of the connecting rod and both ends of the arc-shaped support rod.

[0011] Preferably, the support link includes a first link hinged to the side end of the connecting rod. A first long slot is provided at one end of the first link away from the connecting rod. A second link is hinged to the end of the arc-shaped support rod. A second long slot is provided at one end of the second link away from the arc-shaped support rod. The first link and the second link are fixed by two connecting bolts.

[0012] Preferably, two square holes are provided on the sliding sleeve, and square blocks are arranged in the square holes. A triangular groove is provided inside the square block. A number of connecting ears are fixed on the sliding sleeve, and the connecting ears are located on both sides of the square holes. A connecting seat is provided at the upper end of the square block, and a fixing hole is provided in the connecting seat. An installation bolt is arranged between the two connecting ears, and the installation bolt penetrates through the fixing hole.

[0013] Preferably, a lifting lug is fixed above the central block, and the lifting lug is integrally formed with the central block.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The main body of the casing is supported from the inside by a plurality of support frames to prevent the main body of the casing from deforming. When the casing penetrates deep into the ground, the support frame located below is blocked by the soil inside the main body of the casing. At this time, the arc-shaped support rod and the vertical slide rail slide relative to each other. The support frames inside the main body of the casing will all gather at the part of the main body of the casing above the ground. After moving the support frame upward and disengaging it from the vertical slide rail, the limit on the slide rod and the moving rod is released by the limiting mechanism, so that the moving rod moves along the slide rod towards the central block. Then the support frame can be taken out from the upper end of the main body of the casing. This can not only improve the strength of the casing, but also the support frame can be reused in other casings, reducing costs.

[0015] At the same time, the limiting mechanism can prevent the moving rod from contracting and provide a supporting force for the main body of the casing. When the arc-shaped support rod disengages from the vertical slide rail upward, the limiting mechanism can drive the moving rod to contract, facilitating the removal of the support frame, and it is relatively convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an overall axonometric structural schematic diagram of the present invention.

[0017] Figure 2 It is an internal structural schematic diagram of the main body of the casing in the present invention.

[0018] Figure 3 It is an overall structural schematic diagram of the support frame in the present invention.

[0019] Figure 4 It is a partial structural schematic diagram of the support frame in the present invention.

[0020] Figure 5 It is an internal structural schematic diagram of the sliding sleeve in the present invention.

[0021] Figure 6 Schematic cross-sectional structure diagram of the moving rod in the present invention.

[0022] Figure 7 Schematic disassembly structure diagram of the square block in the present invention.

[0023] In the figure: 1. Casing main body; 2. Hammering sleeve; 3. Vertical slide rail; 4. Cutting inlet; 5. Pointed head; 6. Central block; 7. Support rod; 8. Slide rod; 9. Moving rod; 10. Slide hole; 11. Arc-shaped support rod; 12. Tension spring; 13. Limit block; 14. Sliding sleeve; 15. Thrust rod; 16. Triangular groove; 17. Fixed sleeve; 18. Extension sleeve; 19. First sealing ring; 20. Second sealing ring; 21. Connecting rod; 22. First half-width plate; 23. Second half-width plate; 24. Fixed bolt; 25. First connecting rod; 26. Second connecting rod; 27. Second long slot; 28. First long slot; 29. Connecting bolt; 30. Square hole; 31. Connecting ear; 32. Square block; 33. Connecting seat; 34. Mounting bolt; 35. Lifting lug. Specific embodiments

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0025] As Figures 1-7 shown, the present invention provides a casing for bored cast-in-place piles in foundation pits, including a casing main body 1. A hammering sleeve 2 is provided at the upper end of the casing main body 1, and the hammering sleeve 2 covers the upper edge of the casing main body 1. A cutting inlet 4 is provided at the lower end of the casing main body 1. A plurality of vertically distributed slide rails 3 are fixed on the inner wall of the casing main body 1, and a pointed head 5 is provided at the lower end of the vertical slide rail 3. A plurality of support frames are provided inside the casing main body 1, and the support frames are evenly distributed up and down at equal intervals inside the casing main body 1. The support frame includes a central block 6 located at the center position. A plurality of evenly distributed support rods 7 are connected to the outside of the central block 6, and a slide rod 8 is fixed on the support rod 7. The other end of the slide rod 8 is provided with a moving rod 9. A slide hole 10 is opened on the moving rod 9, and the slide rod 8 is slidably inserted into the slide hole 10. A limiting mechanism is also provided on the moving rod 9 for restricting the sliding of the slide rod 8. An arc-shaped support rod 11 is fixed at the outer end of the moving rod 9. A chute (not marked in the figure) is opened at the middle position of the arc-shaped support rod 11, and the arc-shaped support rod 11 is slidably arranged on the vertical slide rail 3 through the chute.

[0026] It should be noted that multiple support frames are located inside the casing body 1 and can provide support to the casing body 1 from the inside to prevent the casing body 1 from deforming. When the casing penetrates deep into the ground, the hammering sleeve 2 bears the impact force, which can prevent the upper end of the casing body 1 from deforming. The cutting inlet 4 cuts the soil, and the casing body 1 moves downward. The support frames located below are blocked by the soil inside the casing body 1. At this time, the arc-shaped support rod 11 and the vertical slide rail 3 slide relative to each other. When the casing body 1 descends to the set height, the support frames inside it will all gather in the part of the casing body 1 above the ground. After moving the support frame upward and disengaging it from the vertical slide rail 3, the limit on the slide rod 8 and the moving rod 9 is released by the limit mechanism, so that the moving rod 9 moves along the slide rod 8 towards the direction close to the central block 6. Then the support frame can be taken out from the upper end of the casing body 1, and the support frame can be reused in other casings.

[0027] As Figure 6 shown, the limit mechanism includes a sliding sleeve 14 slidably arranged outside the moving rod 9, and a push rod 15 is fixed to the outside of the sliding sleeve 14. One end of the push rod 15 abuts against the vertical slide rail 3, and an inclined surface (not marked in the figure) is arranged at the end of the push rod 15 close to the vertical slide rail 3. Two symmetrically distributed round holes (not marked in the figure) are opened in the sliding sleeve 14. A limit block 13 is slidably arranged in the round hole. One end of the limit block 13 close to the sliding hole 10 is hemispherical, and the other end is an inclined surface. The hemispherical end of the limit block 13 abuts against the end of the slide rod 8. Two triangular grooves 16 with inclined bottoms are opened on the inner surface of the sliding sleeve 14, and the inclined surface of the limit block 13 abuts against the bottom of the triangular groove 16. A tension spring 12 is arranged in the sliding hole 10, and both ends of the tension spring 12 are fixed to the bottom of the sliding hole 10 and the slide rod 8 respectively.

[0028] It should be noted that the moving rod 9 and the slide rod 8 tend to approach each other under the pulling force of the tension spring 12, but due to the blocking of the limit block 13, the moving rod 9 and the slide rod 8 cannot approach each other. Furthermore, it can provide a supporting force from the inside of the casing body 1 to prevent the casing body 1 from deforming. When the support frame moves above the vertical slide rail 3, the push rod 15 loses the blocking of the vertical slide rail 3. At this time, the tension spring 12 pulls the moving rod 9, and the moving rod 9 approaches the slide rod 8. The end of the slide rod 8 abuts against the limit block 13 and forces the limit block 13 to move outward. Since the push rod 15 loses the blocking of the vertical slide rail 3, under the interaction of the triangular groove 16 and the limit block 13, the push rod 15 moves towards the direction close to the inner wall of the casing body 1. Therefore, when the arc-shaped support rod 11 slides on the vertical slide rail 3, the limit mechanism can prevent the moving rod 9 from contracting and provide a supporting force to the casing body 1. When the arc-shaped support rod 11 moves upward and disengages from the vertical slide rail 3, the limit mechanism can drive the moving rod 9 to contract, facilitating the removal of the support frame.

[0029] As Figure 5 and Figure 6As shown in the figure, a fixed sleeve 17 is fixed at one end of the sliding rod 8 inside the sliding hole 10, and the fixed sleeve 17 is sleeved outside the tension spring 12. The outside of the fixed sleeve 17 abuts against the limit block 13. One end of the sliding sleeve 14 close to the central block 6 is provided with an extension sleeve 18, and the extension sleeve 18 is sleeved outside the support rod 7.

[0030] It should be noted that the fixed sleeve 17 can provide a supporting force for the limit block 13 to prevent the limit block 13 from entering the inside of the sliding hole 10 and causing the device to jam. The extension sleeve 18 and the sliding sleeve 14 can cooperate to sleeve the support rod 7 and the moving rod 9 at the same time, improve the connection strength, prevent the sliding rod 8 between the two from bending and deforming when providing a supporting force for the casing main body 1, and improve the structural strength.

[0031] As Figure 5 shown, a number of equally spaced first annular grooves (not marked in the figure) are provided on the outside of the moving rod 9, and a first sealing ring 19 is sleeved in the first annular groove. The outside of the first sealing ring 19 abuts against the inner wall of the sliding sleeve 14. A number of equally spaced second annular grooves (not marked in the figure) are provided on the outside of the support rod 7, and a second sealing ring 20 is sleeved in the second annular groove. The outside of the second sealing ring 20 abuts against the inner wall of the extension sleeve 18.

[0032] It should be noted that the use environment of the casing is generally a mixed environment of mud, water and sand. It is inevitable that the support frame comes into contact with the turbid mixture, or even is directly immersed in the mud and water. When the sliding sleeve 14 and the extension sleeve 18 slide with the inner support rod 7 and the moving rod 9, the first sealing ring 19 and the second sealing ring 20 can prevent impurities such as mud, water and sand from entering the inside, prevent structural wear or jamming, and multiple first sealing rings 19 and second sealing rings 20 can improve the sealing effect.

[0033] As Figure 4 shown, a number of equally spaced connecting rods 21 are fixed on the central block 6. The support rods 7 are respectively connected to the corresponding connecting rods 21. A first half-width plate 22 is provided on the support rod 7, and a second half-width plate 23 is provided on the connecting rod 21. The first half-width plate 22 and the second half-width plate 23 are detachably connected by a plurality of fixing bolts 24, and support connecting rods are provided between both sides of the connecting rod 21 and both ends of the arc-shaped support rod 11.

[0034] It should be noted that the support rod 7 can be disassembled and installed through the fixing bolts 24. In actual use, the support frame can be reused, but the width of the casing main body 1 is different in different construction operations. At this time, the support rod 7 can be disassembled and then connected to the central block 6 with connecting rods 21 of different lengths to improve the reuse effect of the support frame, and the support connecting rods on both sides can further improve the supporting force of the arc-shaped support rod 11.

[0035] AsFigure 4 As shown, the support link includes a first link 25 hinged to the side end of the connecting rod 21. One end of the first link 25 away from the connecting rod 21 is provided with a first long slot 28. The end of the arc-shaped support rod 11 is hinged with a second link 26. One end of the second link 26 away from the arc-shaped support rod 11 is provided with a second long slot 27. And the first link 25 and the second link 26 are fixed by two connecting bolts 29.

[0036] It should be noted that before the connecting bolts 29 are tightened, they can slide in the first long slot 28 and the second long slot 27. Therefore, the length of the support link formed by the first link 25 and the second link 26 is adjustable. By adjusting the length of the support link, the radian of the arc-shaped support rod 11 can be changed. When matching the casing body 1 with different diameters, it can fit more closely to the inner wall of the casing body 1 and play a better supporting effect.

[0037] As Figure 7 shown, two square holes 30 are opened on the sliding sleeve 14, and a square block 32 is arranged in the square holes 30. A triangular groove 16 is opened on the inner side of the square block 32. A number of connecting ears 31 are fixed on the sliding sleeve 14, and the connecting ears 31 are located on both sides of the square holes 30. A connecting seat 33 is arranged at the upper end of the square block 32, and a fixing hole (not marked in the figure) is opened in the connecting seat 33. An installation bolt 34 is arranged between the two connecting ears 31, and the installation bolt 34 penetrates through the fixing hole.

[0038] It should be noted that after the installation bolt 34 is removed, the square block 32 can be taken out of the square hole 30. The inner side of the square block 32 is the limiting block 13. After removing the square block 32, the worn limiting block 13 can be replaced, and maintenance can also be carried out when the equipment is stuck, which is more convenient to operate. Moreover, when assembling the equipment, the sliding sleeve 14 can be first sleeved from one end of the moving rod 9, and then the square hole 30 is aligned with the round hole, which is more convenient for installation.

[0039] As Figure 3 shown, a lifting lug 35 is fixed above the center block 6, and the lifting lug 35 is integrally formed with the center block 6.

[0040] It should be noted that when the casing body 1 is slightly deformed during use, the inner wall of the casing body 1 is pressed against the arc-shaped support rod 11, and it is difficult to take out the support frame by manpower. At this time, a lifting device can be used to lift the entire support frame upward through the lifting lug 35, which is more convenient for actual use.

[0041] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended embodiments and their equivalents.

Claims

1. A casing for a bored cast-in-place pile in a foundation pit, comprising a casing main body (1), characterized in that: A hammering sleeve (2) is provided at the upper end of the casing body (1). The hammering sleeve (2) covers the upper edge of the casing body (1). A cutting inlet (4) is provided at the lower end of the casing body (1). A plurality of vertically distributed vertical slide rails (3) are fixed on the inner wall of the casing body (1), and a pointed end (5) is provided at the lower end of the vertical slide rail (3). A plurality of support frames are provided inside the casing body (1), and the support frames are vertically distributed at equal intervals inside the casing body (1). The support frame includes a central block (6) located at the central position. A plurality of support rods (7) are connected to the outside of the central block (6) at equal intervals. A slide rod (8) is fixed on the support rod (7). A moving rod (9) is provided at the other end of the slide rod (8). A slide hole (10) is formed in the moving rod (9), and the slide rod (8) is slidably inserted into the slide hole (10). A limiting mechanism is further provided on the moving rod (9) for limiting the sliding of the slide rod (8). An arc-shaped support rod (11) is fixed at the outer end of the moving rod (9). A chute is formed at the middle position of the arc-shaped support rod (11), and the arc-shaped support rod (11) is slidably arranged on the vertical slide rail (3) through the chute.

2. The casing for a bored cast-in-place pile in a foundation pit according to claim 1, characterized in that: The limiting mechanism includes a sliding sleeve (14) slidably arranged on the outside of the moving rod (9). A push rod (15) is fixed on the outside of the sliding sleeve (14). One end of the push rod (15) abuts against the vertical slide rail (3), and an inclined surface is provided at the end of the push rod (15) close to the vertical slide rail (3). Two symmetrically distributed circular holes are formed in the sliding sleeve (14). A limiting block (13) is slidably arranged in the circular holes. One end of the limiting block (13) close to the slide hole (10) is hemispherical, and the other end is an inclined surface. The hemispherical end of the limiting block (13) abuts against the end of the slide rod (8). Two triangular grooves (16) with inclined bottoms are formed on the inner surface of the sliding sleeve (14), and the inclined surface of the limiting block (13) abuts against the bottom of the triangular groove (16). A tension spring (12) is arranged in the slide hole (10), and both ends of the tension spring (12) are fixed to the bottom of the slide hole (10) and the slide rod (8) respectively.

3. The casing for bored cast-in-place pile in foundation pit according to claim 2, characterized in that: A fixing sleeve (17) is fixed at the end of the slide rod (8) inside the slide hole (10). The fixing sleeve (17) is sleeved on the outside of the tension spring (12). The outside of the fixing sleeve (17) abuts against the limiting block (13). An extension sleeve (18) is provided at the end of the sliding sleeve (14) close to the central block (6). The extension sleeve (18) is sleeved on the outside of the support rod (7).

4. A casing for a bored cast-in-place pile in a foundation pit according to claim 3, characterized in that: A plurality of first annular grooves are formed at equal intervals on the outside of the moving rod (9), and a first sealing ring (19) is sleeved in the first annular grooves. The outside of the first sealing ring (19) abuts against the inner wall of the sliding sleeve (14). A plurality of second annular grooves are formed at equal intervals on the outside of the support rod (7), and a second sealing ring (20) is sleeved in the second annular grooves. The outside of the second sealing ring (20) abuts against the inner wall of the extension sleeve (18).

5. The casing for a bored cast-in-place pile in a foundation pit according to claim 1, characterized in that: A number of connecting rods (21) evenly distributed at equal intervals are fixed on the central block (6). The support rods (7) are respectively connected to the corresponding connecting rods (21). A first half-width plate (22) is arranged on the support rod (7), and a second half-width plate (23) is arranged on the connecting rod (21). The first half-width plate (22) and the second half-width plate (23) are detachably connected by a plurality of fixing bolts (24). And support connecting rods are arranged between both sides of the connecting rod (21) and both ends of the arc-shaped support rod (11).

6. The casing for bored cast-in-place pile in foundation pit according to claim 5, characterized in that: The support connecting rod includes a first connecting rod (25) hinged to the side end of the connecting rod (21). A first long slot (28) is arranged at one end of the first connecting rod (25) away from the connecting rod (21). A second connecting rod (26) is hinged to the end of the arc-shaped support rod (11). A second long slot (27) is opened at one end of the second connecting rod (26) away from the arc-shaped support rod (11). And the first connecting rod (25) and the second connecting rod (26) are fixed by two connecting bolts (29).

7. A casing for a bored cast-in-place pile in a foundation pit according to claim 2, characterized in that: Two square holes (30) are opened on the sliding sleeve (14). And a square block (32) is arranged in the square hole (30). A triangular groove (16) is opened on the inner side of the square block (32). A number of connecting ears (31) are fixed on the sliding sleeve (14), and the connecting ears (31) are located on both sides of the square hole (30). A connecting seat (33) is arranged at the upper end of the square block (32), and a fixing hole is opened in the connecting seat (33). An installation bolt (34) is arranged between the two connecting ears (31), and the installation bolt (34) penetrates through the fixing hole.

8. A casing for a bored cast-in-place pile in a foundation pit according to claim 1, characterized in that: A lifting lug (35) is fixed above the central block (6), and the lifting lug (35) is integrally formed with the central block (6).

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