Construction method of deep foundation pit retaining piles in open excavation section of access line

Abstract

The present invention discloses a method for constructing retaining piles for a deep foundation pit in an open-cut section of an access line. During the construction of the retaining piles, a transfer platform is provided to transport a horizontally placed steel cage, and the steel cage is quickly moved to the vicinity of a pile hole. Then, the transfer platform is used as a bottom support, and a lifting device is used to adjust the steel cage from a horizontal state to a vertical state, thereby realizing rapid steering adjustment of the steel cage, shortening the distance and time for the steel cage to reach the pile hole after being manufactured, and facilitating improving the pile hole construction efficiency of the retaining piles.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation pit construction, and more specifically, to a method for constructing deep foundation pit retaining piles in an open excavation interval of an access line. Background Art

[0002] During the construction of deep foundation pit retaining piles in the open excavation section of the entry and exit lines, the steel cage needs to be processed and hoisted into the pile hole after the drilling is completed. Before hoisting the steel cage, the steel cage needs to be moved to the vicinity of the pile hole and then lifted. If the required steel cage is relatively long, it needs to be hoisted in sections. During the lifting process, multiple lifting points need to be set for a single steel cage to lift it simultaneously, and then the steel cage is adjusted to a vertical state in the air, and finally slowly lowered to the pile hole. The whole process mainly relies on the truck crane to lift and move the steel cage, which is slow, affecting the overall construction efficiency of the retaining piles. When the truck crane is lifting the steel cage, it even requires manual cooperation to pull the steel cage, which also poses a safety risk. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] Another object of the present invention is to provide a method for constructing deep foundation pit retaining piles in an open excavation section of an access line, so as to solve the technical problem of low efficiency in lifting steel cages during retaining pile construction in the prior art.

[0005] In order to achieve these purposes and other advantages according to the present invention, a method for constructing deep foundation pit retaining piles in an open excavation interval of an access line is provided, comprising the following steps:

[0006] S1. Drilling and cleaning the pile holes for retaining piles;

[0007] S2, making a steel cage, setting up a transfer platform, setting walking wheels for driving the transfer platform at the bottom of the transfer platform, placing the steel cage horizontally on the transfer platform, and moving the transfer platform to the vicinity of the pile hole;

[0008] S3, using a lifting device to lift the steel cage on the transfer platform and adjust the steel cage to a vertical state on the transfer platform;

[0009] S4, after the steel cage of step S3 is translated to the top of the pile hole to be constructed, it falls into the pile hole and takes place;

[0010] S5. After placing the guide tube in the pile hole, clean the hole for the second time and then pour underwater concrete.

[0011] Preferably, the transfer platform comprises:

[0012] The bottom plate is arranged horizontally, the walking wheels are arranged at the bottom of the bottom plate, the upper surface of the bottom plate is used to place the steel cage along the length direction, a two-stage stepped trough is opened outward along the length direction at one end of the bottom plate, and a baffle is arranged at the other end, a driving motor is installed on one side of the lower step of the trough, and the output shaft of the driving motor is parallel to the width direction of the bottom plate and a convex key is arranged on the surface;

[0013] A limiting cylinder is placed on the upper surface of the upper step of the trough platform and is axially penetrated, the axial direction of the limiting cylinder is consistent with the length direction of the bottom plate, the inner cross-sectional size of the limiting cylinder is larger than the outer diameter of the steel cage, the inner side of the limiting cylinder is flush with the surface of the bottom plate at the lowest height, the limiting cylinder extends along the length direction of the bottom plate to the top of the lower step of the trough platform on the side in contact with the upper surface of the upper step of the trough platform and is connected with a sleeve, a groove is provided on the inner side of the sleeve corresponding to the convex key, the sleeve is axially sleeved on the output shaft of the driving motor after the groove is aligned with the convex key, and when the limiting cylinder rotates 90° toward the outer side of the bottom plate along the output shaft of the driving motor, the bottom of the limiting cylinder just contacts the upper surface of the lower step of the trough platform;

[0014] When the steel cage is placed horizontally on the transfer platform, the axial direction of the limiting cylinder is horizontal, and then the steel cage is placed on the bottom plate, and one end of the steel cage is extended into the limiting cylinder. After the transfer platform is driven to move to the vicinity of the pile hole, the lifting device lifts the steel cage and starts the drive motor to rotate 90° at the same time so that the opening of the limiting cylinder faces upward, so as to cooperate with the rotation of the steel cage to a vertical state. At this time, the limiting cylinder is placed on the upper surface of the lower step of the trough platform, and the lifting device will be in a vertical state and then continue to step S4.

[0015] Preferably, the limiting cylinder is formed by a C-shaped cylinder and a cover plate detachably connected, and the sleeve is connected to the outer side of the end portion on one side of the middle of the C-shaped cylinder;

[0016] Before placing the steel cage on the base plate, remove the cover plate and place the steel cage on the base plate by the lifting equipment. At this time, one end of the steel cage is located in the C-shaped cylinder. Then the cover plate and the C-shaped cylinder are spliced ​​to form the limiting cylinder. After that, the drive motor is started and rotated 90° to rotate the steel cage to a vertical state.

[0017] Preferably, the cover plate extends horizontally and radially outward at the end portion on the opposite side of the sleeve to form a shelf, and a limiting frame is fixed on the top peripheral ground at the pile hole, the limiting frame includes a horizontally arranged square frame, the center of the square frame is aligned with the axis of the pile hole, a reinforcing plate is connected to each top corner of the square frame, and the reinforcing plate is provided with a docking groove on one side facing the center of the square frame, the shelf and the sleeve are symmetrically arranged at both ends of the bottom of the limiting cylinder and have an overall size larger than the pile hole, and docking blocks are respectively arranged at the outer end top corners of the sleeve and the shelf, and each docking block is embedded in a docking groove when the opening direction of the limiting cylinder is facing upward and placed on the inner side of the square frame;

[0018] After the steel cage is adjusted to a vertical state by using the limiting cylinder, the limiting cylinder is moved as a whole along the axial direction of the output shaft of the driving motor. As the lifting equipment is translated synchronously, the sleeve is allowed to leave the output shaft of the driving motor until it is transferred to the square frame, and each docking block and docking groove are aligned, so that the inner axis of the limiting cylinder is aligned with the axis of the pile hole, and then the steel cage is lowered into the pile hole along the inner side of the limiting cylinder.

[0019] Preferably, the cover plate and the middle side of the C-shaped tube are provided with hanging ears at the end facing away from the sleeve, and each pair of hanging ears has a rod inserted therein;

[0020] After the steel cage is adjusted to a vertical state, an insertion rod is inserted into each pair of hanging ears, and the insertion rod passes through the corresponding position of the steel cage. Then, the lifting equipment is used to lift and translate the steel cage. At this time, the limiting cylinder is synchronously moved at the bottom of the steel cage by the insertion rod. Then, when the steel cage moves to the top of the limiting frame, the position of the limiting cylinder is adjusted to make the docking block embedded in the docking groove, and the lifting equipment synchronously pulls the upper end of the steel cage to quickly position the steel cage at the center of the pile hole.

[0021] Preferably, the outer side of the limiting cylinder is a square structure in the radial cross-sectional direction, and the inner side of the C-shaped cylinder is an arc-shaped structure arranged toward the cover plate.

[0022] Preferably, a limit seat is provided on the surface of the base plate, and a plurality of limit seats are arranged at intervals along the length direction of the base plate and are located in the same vertical plane as the inner axial direction of the C-shaped cylinder. One of the steel cages is horizontally placed on a row of limit seats and the radial direction of the steel cage is limited by the limit seats.

[0023] Preferably, a counterweight block is provided at the bottom of the opposite end of the bottom plate and the limiting cylinder.

[0024] The present invention includes at least the following beneficial effects: the method for constructing retaining piles for deep foundation pits in the open-cut section of the entry and exit lines of the present invention provides a transfer platform to transport the horizontally placed steel cage during the construction of the retaining piles, quickly moves the steel cage to the vicinity of the pile hole, and then uses the transfer platform as a bottom support and cooperates with the lifting equipment to adjust the steel cage from a horizontal state to a vertical state, thereby realizing rapid steering adjustment of the steel cage, shortening the distance and time for the steel cage to reach the pile hole after production, which is beneficial to improving the pile hole construction efficiency of the retaining piles.

[0025] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a main structural diagram of the steel cage of the present invention placed horizontally on a transfer platform;

[0027] Figure 2 This is a front structural diagram of the limiting cylinder of the present invention when it is adjusted to be axially vertical;

[0028] Figure 3 It is a top view of the structure of the limiting cylinder of the present invention;

[0029] Figure 4 This is a top view of the structure in which a limiting cylinder is docked in the middle of a limiting frame in an embodiment of the present invention.

[0030] Figure numerals in the specification: 1. steel cage, 2. transfer platform, 3. walking wheel, 4. pile hole, 5. bottom plate, 6. upper step of trough platform, 7. lower step of trough platform, 8. baffle, 9. driving motor, 10. cam, 11. limiting cylinder, 12. sleeve, 13. C-shaped cylinder, 14. cover plate, 15. shelf, 16. square frame, 17. reinforcement plate, 18. docking groove, 19. hanging ear, 20. limiting seat, 21. counterweight. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the materials can be obtained from commercial channels unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0033] like Figure 1-4 As shown, the present invention provides a method for constructing deep foundation pit retaining piles in an open excavation interval of an access line, comprising the following steps:

[0034] S1. Drill and clean the pile holes 4 of the retaining piles.

[0035] After the casing is buried at the upper end of the pile hole 4, the drilling rig is in place, the drill bit is aligned with the pile position, and the rotary drilling is used for hole drilling. The mud circulation system of the rotary drilling is composed of a mud pool, a sedimentation tank, a mud pump, etc., and drainage and slurry discharge facilities are set. After the hole is drilled to the designed depth, the hole depth, hole diameter, verticality, mud concentration, sediment thickness and other indicators are tested and checked. Only after confirming that they meet the requirements can the next process be carried out. After the hole is drilled, the hole is cleaned with a rotary drilling hole cleaning drill bit to remove the sediment at the bottom of the hole, and the mud viscosity is measured as the hole is cleaned. When the mud viscosity is 35-45s from the hole to the exit, and the sediment thickness at the bottom of the hole is not more than 10cm, the hole cleaning is completed and the next process is entered.

[0036] S2, make a steel cage 1, set up a transfer platform 2, set walking wheels 3 at the bottom of the transfer platform 2 for driving the transfer platform 2 to walk, place the steel cage 1 horizontally on the transfer platform 2, and move the transfer platform 2 to the vicinity of the pile hole 4.

[0037] To prevent the steel cage 1 from twisting and deforming when it is hoisted, a reinforcing hoop with a diameter of 20mm is generally added every 2.0m inside the main reinforcement, and the main reinforcement is welded on site. Four 20mm earrings are set every 5m on the main reinforcement on the four sides of the steel cage 1 as positioning pads to keep the protective layer at 70mm. The allowable deviations for the production and hoisting of the steel skeleton are: main reinforcement spacing ±10mm; hoop spacing ±20mm; skeleton outer diameter ±10m; skeleton inclination ±0.5%; skeleton protective layer thickness ±20mm; skeleton center plane position 20mm; skeleton top elevation ±20mm; skeleton bottom elevation ±50mm. The steel cage 1 is transported to the vicinity of the pile hole 4 by the transfer platform 2. The walking wheel 3 is also driven by an electric control or remote control drive structure as needed to achieve automatic walking.

[0038] S3. Use the lifting equipment to lift the steel cage 1 on the transfer platform 2 and adjust the steel cage 1 to a vertical state on the transfer platform 2. The steel cage 1 is hoisted in place by a 25t truck crane. The horizontal hoisting is still transported by a flatbed truck. The steel cage 1 is turned from horizontal to vertical by the main hook and auxiliary hook of the crane. It is flipped in the air, and the transfer platform 2 is used as the bottom support or flip fulcrum of the steel cage 1. After it is upright and stabilized, all the steel bars are borne by the main hook.

[0039] S4, after the steel cage 1 of step S3 is horizontally moved to the top of the pile hole 4 to be constructed, it is dropped into the pile hole 4 and put into place. The automobile hoist drives the steel cage 1 to slowly drop into the pile hole 4 and put it into place. During the process of lowering, the auxiliary hook is unhooked. After lowering into place, two No. 16 channel steel cross arms are passed through the top hoisting ring of the steel cage 1, and it is hung at the hole mouth and then the main hook is removed.

[0040] S5. After placing the guide tube in the pile hole 4, the hole is cleaned for the second time and then poured with underwater concrete.

[0041] Operations such as hole cleaning, lowering of guide tubes, and pouring of underwater concrete can be carried out using existing technologies, which will not be described in detail here. By setting up a transfer platform 2, the steel cage 1 can be quickly moved to the vicinity of the pile hole 4, and then the transfer platform 2 is used as the bottom support to facilitate the steering adjustment of the steel cage 1 by the lifting equipment, thereby shortening the transportation distance and time of the steel cage 1 to reach the pile hole 4 after production, which is beneficial to improving the construction efficiency of the pile hole 4 of the retaining pile.

[0042] The shelf 15 is flush with the outer end of the sleeve 12 in the axial direction of the limiting cylinder 11 .

[0043] In another technical solution, Figure 1-4 As shown, the transfer platform 2 includes:

[0044] The bottom plate 5 is horizontally arranged, the walking wheel 3 is arranged at the bottom of the bottom plate 5, the upper surface of the bottom plate 5 is used to place the steel cage 1 along the length direction, the bottom plate 5 is provided with a two-stage stepped slot outward along the length direction at one end thereof, and a baffle 8 is arranged at the other end thereof, a driving motor 9 is installed on one side of the lower step 7 of the slot, the output shaft of the driving motor 9 is parallel to the width direction of the bottom plate 5 and a convex key 10 is arranged on the surface thereof;

[0045] The limiting cylinder 11 is placed on the upper surface of the upper step 6 of the slot table and is axially penetrated. The axial direction of the limiting cylinder 11 is consistent with the length direction of the bottom plate 5. The inner cross-sectional size of the limiting cylinder 11 is larger than the outer diameter of the steel cage 1. The inner side of the limiting cylinder 11 is flush with the surface of the bottom plate 5 at the lowest height. The limiting cylinder 11 extends along the length direction of the bottom plate 5 to the top of the lower step 7 of the slot table on the side in contact with the upper surface of the upper step 6 of the slot table and is connected with a sleeve 12. The inner side of the sleeve 12 is provided with a groove corresponding to the convex key 10. The sleeve 12 is axially sleeved on the output shaft of the drive motor 9 after the groove is aligned with the convex key 10. When the limiting cylinder 11 rotates 90° toward the outside of the bottom plate 5 along the output shaft of the drive motor 9, the bottom of the limiting cylinder 11 just contacts the upper surface of the lower step 7 of the slot table.

[0046] When the steel cage 1 is placed horizontally on the transfer platform 2, the axial direction of the limiting cylinder 11 is horizontal, and then the steel cage 1 is placed on the bottom plate 5, and one end of the steel cage 1 is extended into the limiting cylinder 11, and then the transfer platform 2 is driven to move to the vicinity of the pile hole 4, the lifting equipment lifts the steel cage 1, and at the same time starts the drive motor 9 to rotate 90° so that the opening of the limiting cylinder 11 faces upward, so as to cooperate with the rotation of the steel cage 1 to a vertical state. At this time, the limiting cylinder 11 is placed on the upper surface of the lower step 7 of the trough table, and the lifting equipment will be in a vertical state and then continue to step S4.

[0047] Before transporting the steel cage 1, one end of the steel cage 1 is placed in the limiting cylinder 11, which is beneficial to the limiting protection of the steel cage 1 during transportation. When the transfer platform 2 moves to the vicinity of the pile hole 4, the steel cage 1 is towed by a lifting equipment such as a car crane, and the drive motor 9 is controlled to rotate at a lower speed, thereby driving the limiting cylinder 11 to rotate to cooperate and guide the steel cage 1 to adjust its state, and the bottom plate 5 can also be used as a platform support during the adjustment process. The construction method of this scheme improves the adjustment efficiency and operation safety of the lifting equipment.

[0048] In another technical solution, Figure 1-4 As shown, the limiting cylinder 11 is formed by a C-shaped cylinder 13 and a cover plate 14 which are detachably connected, and the sleeve 12 is connected to the outer side of the end portion of the middle side of the C-shaped cylinder 13;

[0049] Before placing the steel cage 1 on the base plate 5, remove the cover plate 14 and place the steel cage 1 on the base plate 5 by the lifting equipment. At this time, one end of the steel cage 1 is located in the C-shaped cylinder 13. Then, the cover plate 14 and the C-shaped cylinder 13 are spliced ​​to form the limiting cylinder 11. After that, the drive motor 9 is started and rotated 90° to rotate the steel cage 1 to a vertical state.

[0050] By configuring the limiting cylinder 11 as a detachably connected combined structure, it is more flexible when placing the reinforcement cage 1, and the construction efficiency is further improved.

[0051] In another technical solution, Figure 1-4 As shown, the cover plate 14 extends radially outward horizontally at the end on the side opposite to the sleeve 12 to form a shelf 15, and a limiting frame is fixed on the top peripheral ground at the pile hole 4, the limiting frame includes a horizontally arranged square frame 16, the center of the square frame 16 is aligned with the axis of the pile hole 4, and a reinforcing plate 17 is connected to each vertex of the square frame 16, and the reinforcing plate 17 is provided with a docking groove 18 on one side facing the center of the square frame 16, the shelf 15 and the sleeve 12 are symmetrically arranged at both ends of the bottom of the limiting tube 11 and the overall size is larger than the pile hole 4, and docking blocks are respectively arranged at the outer end vertex corners of the sleeve 12 and the shelf 15, and when the opening direction of the limiting tube 11 is facing upward and placed on the inner side of the square frame 16, each docking block is embedded in a docking groove 18;

[0052] After the steel cage 1 is adjusted to a vertical state by using the limiting cylinder 11, the limiting cylinder 11 is moved as a whole along the axial direction of the output shaft of the driving motor 9. As the lifting equipment is synchronously translated, the sleeve 12 leaves the output shaft of the driving motor 9 until it is transferred to the square frame 16, and each docking block is aligned with the docking groove 18, so that the inner axis of the limiting cylinder 11 is aligned with the axis of the pile hole 4, and then the steel cage 1 is lowered into the pile hole 4 along the inner side of the limiting cylinder 11.

[0053] After the limiting cylinder 11 becomes vertical, the limiting cylinder 11 can be manually moved outward along the axial direction of the output shaft of the driving motor 9, so that the limiting cylinder 11 gradually separates from the output shaft of the driving motor 9. During the movement, the automobile crane synchronously translates the lifted steel cage 1, or the limiting cylinder 11 is manually moved to cooperate with the movement of the automobile crane. Since the limiting cylinder 11 is a through structure, during the translation of the steel cage 1, the position of the limiting cylinder 11 can be manually adjusted up and down as needed to facilitate the movement of the limiting cylinder 11. When the limiting cylinder 11 and the steel cage 1 move to the pile hole 4, the automobile crane moves following the adjustment of the limiting cylinder 11, and the docking block is manually embedded in the docking groove 18, and the shelf 15 and the sleeve 12 are jointly supported on the ground outside the pile hole, thereby completing the positioning of the limiting cylinder 11, thereby quickly realizing the positioning of the steel cage 1, which is beneficial to the subsequent lowering process of the steel cage 1.

[0054] In another technical solution, Figure 1-3 As shown, the cover plate 14 and the middle side of the C-shaped tube 13 are provided with hanging ears 19 opposite to each other at the end facing away from the sleeve 12, and each pair of hanging ears 19 has a rod inserted therein;

[0055] After the steel cage 1 is adjusted to a vertical state, a rod is inserted into each pair of hanging ears 19, and the rod passes through the corresponding position of the steel cage 1. Then, the lifting equipment is used to lift and translate the steel cage 1. At this time, the limiting cylinder 11 is synchronously moved at the bottom of the steel cage 1 by the rod. Then, when the steel cage 1 moves to the top of the limiting frame, the position of the limiting cylinder 11 is adjusted to make the docking block embedded in the docking groove 18, and the lifting equipment synchronously pulls the upper end of the steel cage 1 so that the steel cage 1 is quickly located at the center of the pile hole 4.

[0056] The limiting cylinder 11 as a whole can be set as a light-weight structure, so that when it is supported at the bottom of the steel cage 1 by inserting a rod, deformation tension on the steel cage 1 is avoided, and the trouble of manual operation is reduced. Manual operation only needs to align the limiting cylinder 11 near the pile hole 4.

[0057] In another technical solution, Figure 3-4 As shown, the outer side of the limiting cylinder 11 is a square structure in the radial cross-sectional direction, and the inner side of the C-shaped cylinder 13 is an arc-shaped structure arranged toward the cover plate 14 .

[0058] By setting the left side of the C-shaped cylinder 13 to be arc-shaped, on the one hand, it is convenient to limit the storage of the steel cage 1 when the steel cage 1 is horizontally oriented, and on the other hand, it plays a certain limiting and guiding role when the steel cage 1 is lowered. The inner side size of the limiting cylinder 11 is slightly larger than the maximum diameter of the steel cage 1.

[0059] In another technical solution, Figure 1-2 As shown, a limit seat 20 is provided on the surface of the base plate 5, and a plurality of limit seats 20 are arranged at intervals along the length direction of the base plate 5, and are located in the same vertical plane as the inner axial direction of the C-shaped cylinder 13. One of the steel cages 1 is horizontally placed on a row of limit seats 20 and the radial direction of the steel cage 1 is limited by the limit seats 20.

[0060] By providing the limiting seat 20 , the steel cage 1 is limited when the transfer platform 2 moves, thereby preventing the steel cage 1 from rolling off the bottom plate 5 .

[0061] In another technical solution, Figure 1-2 As shown, a counterweight block 21 is arranged at the bottom of the opposite end of the bottom plate 5 and the limiting cylinder 11. The counterweight block 21 is arranged to improve the balance of the left and right ends of the entire transfer platform 2.

[0062] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for constructing deep foundation pit retaining piles in an open excavation section of an access line, characterized in that: The steps include: S1. Drilling and cleaning the pile holes for retaining piles; S2. Make a steel cage and set up a transfer platform. The bottom of the transfer platform is provided with walking wheels for driving the transfer platform to walk. The transfer platform includes: The bottom plate is arranged horizontally, the walking wheels are arranged at the bottom of the bottom plate, the upper surface of the bottom plate is used to place the steel cage along the length direction, a two-stage stepped trough is opened outward along the length direction at one end of the bottom plate, and a baffle is arranged at the other end, a driving motor is installed on one side of the lower step of the trough, and the output shaft of the driving motor is parallel to the width direction of the bottom plate and a convex key is arranged on the surface; The limiting cylinder is placed on the upper surface of the upper step of the trough platform and is axially penetrated, the axial direction of the limiting cylinder is consistent with the length direction of the bottom plate, the inner cross-sectional size of the limiting cylinder is larger than the outer diameter of the steel cage, the inner side of the limiting cylinder is flush with the surface of the bottom plate at the lowest height, the limiting cylinder extends along the length direction of the bottom plate to the top of the lower step of the trough platform on the side in contact with the upper surface of the upper step of the trough platform and is connected with a sleeve, the inner side of the sleeve is provided with a groove corresponding to the convex key, the sleeve is axially sleeved on the output shaft of the driving motor after the groove is aligned with the convex key, when the limiting cylinder rotates 90° toward the outer side of the bottom plate with the output shaft of the driving motor, the bottom of the limiting cylinder just contacts the upper surface of the lower step of the trough platform; the limiting cylinder is detachably connected by a C-shaped cylinder and a cover plate, the sleeve is connected to the outer side of the end of the middle side of the C-shaped cylinder; the outer side of the limiting cylinder is a square structure in the radial cross-sectional direction, and the inner side of the C-shaped cylinder is an arc-shaped structure arranged toward the cover plate; Before placing the steel cage on the bottom plate, the cover plate is disassembled, and the axial direction of the limiting cylinder is horizontal. The steel cage is horizontally placed on the transfer platform, and the steel cage is placed on the bottom plate by a lifting device. At this time, one end of the steel cage is located in the C-shaped cylinder, and then the cover plate and the C-shaped cylinder are spliced ​​to form the limiting cylinder, and then the transfer platform is driven to move to the vicinity of the pile hole; S3, using the lifting equipment to lift the steel cage on the transfer platform, and at the same time start the drive motor to rotate 90 degrees so that the opening of the limit cylinder faces upward, and rotate the steel cage to a vertical state on the transfer platform, at which time the limit cylinder is placed on the upper surface of the lower step of the trough platform; S4, after the steel cage of step S3 is translated to the top of the pile hole to be constructed, it falls into the pile hole and takes place; S5. After placing the guide tube in the pile hole, clean the hole for the second time and then pour underwater concrete.

2. The method for constructing deep foundation pit retaining piles in the open excavation section of the access line according to claim 1, characterized in that: The cover plate is horizontally extended radially outward at the end on the side opposite to the sleeve to form a shelf, and a limiting frame is fixed on the top peripheral ground at the pile hole, the limiting frame includes a horizontally arranged square frame, the center of the square frame is aligned with the axis of the pile hole, a reinforcing plate is connected to each top corner of the square frame, and the reinforcing plate is provided with a docking groove on the side facing the center of the square frame, the shelf and the sleeve are symmetrically arranged at both ends of the bottom of the limiting cylinder and the overall size is larger than the pile hole, and docking blocks are respectively arranged at the outer end top corners of the sleeve and the shelf, and each docking block is embedded in a docking groove when the opening direction of the limiting cylinder is facing upward and placed on the inner side of the square frame; After the steel cage is adjusted to a vertical state by using the limiting cylinder, the limiting cylinder is moved as a whole along the axial direction of the output shaft of the driving motor. As the lifting equipment is translated synchronously, the sleeve is allowed to leave the output shaft of the driving motor until it is transferred to the square frame, and each docking block and docking groove are aligned, so that the inner axis of the limiting cylinder is aligned with the axis of the pile hole, and then the steel cage is lowered into the pile hole along the inner side of the limiting cylinder.

3. The method for constructing deep foundation pit retaining piles in the open excavation section of the access line as claimed in claim 2, characterized in that: The cover plate and the middle side of the C-shaped tube are provided with hanging ears at the end facing away from the sleeve, and each pair of hanging ears has a rod inserted therein; After the steel cage is adjusted to a vertical state, an insertion rod is inserted into each pair of hanging ears, and the insertion rod passes through the corresponding position of the steel cage. Then, the lifting equipment is used to lift and translate the steel cage. At this time, the limiting cylinder is synchronously moved at the bottom of the steel cage by the insertion rod. Then, when the steel cage moves to the top of the limiting frame, the position of the limiting cylinder is adjusted to make the docking block embedded in the docking groove, and the lifting equipment synchronously pulls the upper end of the steel cage to quickly position the steel cage at the center of the pile hole.

4. The method for constructing deep foundation pit retaining piles in the open excavation section of the access line according to claim 1, characterized in that: A limiting seat is arranged on the surface of the bottom plate, and a plurality of limiting seats are arranged at intervals along the length direction of the bottom plate and are located in the same vertical plane as the inner axial direction of the C-shaped cylinder. One steel cage is horizontally placed on a row of limiting seats and the radial direction of the steel cage is limited by the limiting seats.

5. The method for constructing deep foundation pit retaining piles in the open excavation section of the access line according to claim 1, characterized in that: A counterweight block is arranged at the bottom of the opposite end of the bottom plate and the limiting cylinder.

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