Partial pre-bored precast pile self-balanced jacking construction method

Abstract

The present invention provides a self-balanced pressing construction method for partially pre-bored precast piles. In this solution, a steel pipe is pressed into the soil for partial pre-boring, and the precast pile is vertically hoisted into the pre-bored hole and then fixedly spliced. After the precast pile is hoisted to the bottom, it is pressed into the soil. The construction steps are repeated until all the precast pile units are pressed to the top of the steel pipe. Finally, synchronous grouting is carried out while the steel pipe is pulled out. On the one hand, this solution reduces the construction volume by using the method of partial pre-boring, which not only improves the construction speed but also avoids slurry wall protection, meeting the requirements of green environmental protection during the construction of precast piles. On the other hand, this solution also combines the self-balanced method, which greatly reduces the force required to remove the steel pipe compared to the traditional operation of pulling out the steel pipe at the end of the construction, meeting the requirements of economic energy conservation.

Description

Technical Field

[0001] The present invention relates to the field of pile foundations in foundation engineering, and particularly to a self-balanced pressing construction method for partially predrilled precast piles. Background Art

[0002] With the continuous development of China's modernization drive, which focuses on promoting in the direction of technology, the construction technology methods of precast piles in the field of pile foundations in the construction engineering industry also need to be continuously developed, including driven piles, vibro-driven piles, jacked piles, jetting piles, bored and cast-in-place piles, etc.

[0003] For the construction method of precast piles, while ensuring the smooth driving of the pile body, it is also necessary to consider construction efficiency, time-cost benefit, and environmental impact factors. For a certain current precast pile construction method, these factors cannot be comprehensively considered. If the construction method can be technically improved, the disadvantages can be greatly reduced and the adverse situations during construction can be minimized.

[0004] Therefore, at present, a method that comprehensively considers construction factors can be sought, which can not only improve construction efficiency but also meet the effect of green environmental protection while saving costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a self-balanced pressing construction method for partially predrilled precast piles. This solution effectively reduces the amount of soil drilling and avoids slurry wall protection through partial predrilling, while also reducing the amount of cement slurry. By adopting the self-balanced method, the construction speed is increased and the construction cost is saved.

[0006] The purpose of the present invention is achieved through the following technical solutions: A construction method for self-balanced pressing of partially predrilled precast piles includes the following steps:

[0007] Step 1: Press the steel pipe: Arrange the grouting pipe on the outer side of the steel pipe, and then set the first bolt holes on both sides of the upper part of the steel pipe; press the steel pipe into the soil body, and make the first bolt holes on the steel pipe higher than the ground;

[0008] Step 2: After all the soil in the steel pipe is removed, form a predrilled hole in the steel pipe, and the predrilled hole reaches the bottom of the steel pipe;

[0009] Step 3: Lift and place the precast pile unit and connect the piles to the bottom of the predrilled hole. The steps are as follows:

[0010] S1: Use a crane to lift a section of precast bottom pile and lift it into the steel pipe; when the precast bottom pile falls into the steel pipe and its top just exceeds the top of the steel pipe, temporarily fix the precast bottom pile with a fixing frame;

[0011] S2: Lift the precast pile unit by the crane and connect the precast pile unit to the top of the precast bottom pile;

[0012] S3: Loosen the fixing frame, use a crane to lift and lower the connected pile body. When the top end of the pile body reaches the top position of the steel pipe, temporarily fix the top end of the pile body with the fixing frame.

[0013] S4: Repeat construction steps S2 and S3, and successively install precast pile units on the upper end of the completed pile body until the lower end of the pile body reaches the bottom of the pilot hole.

[0014] Step Four: Install the unit: Install the machine base at the position of the first bolt hole provided on the upper part of the steel pipe by means of bolt connection, and install the hoist unit on the machine base.

[0015] Step Five: Connect the piles: Use a crane to lift a precast pile unit and connect the precast pile unit to the top end of the completed pile body.

[0016] Step Six: Place the pressure frame: Lift the pressure frame to the upper end of the pile body by a crane and fix the pressure frame to the upper end of the pile body with bolts.

[0017] Step Seven: Connect the hoist unit and the pressure frame: Connect the two pressure frame ear plates on both sides below the pressure frame to the hoist units on both sides of the upper part of the steel pipe through steel strands.

[0018] Step Eight: Start the hoist unit: Connect the hoist unit to the power supply, turn on the power supply and start the hoist unit, so that the hoist units on both sides of the upper part of the steel pipe pull the pressure frame to move downward at the same speed, and press the pile body into the soil through the pressure frame until the pile body is pressed into the set depth.

[0019] Step Nine: Disconnect the connection between the unit and the pressure frame: Disconnect the connection between the hoist unit and the pressure frame, remove the bolts connecting the pressure frame and the top of the pile body, and remove the pressure frame from the top end of the pile body.

[0020] Step Ten: Repeat steps Five to Nine until all precast pile units are pressed into the steel pipe.

[0021] Step Eleven: Pull out the steel pipe and simultaneously grout: Remove the machine base and the hoist unit on the steel pipe, and place the mortar spray guns in each grouting pipe respectively; slowly and evenly pull out the steel pipe with a crane, and at the same time grout the vacant position after the steel pipe is pulled out; when the steel pipe is completely pulled out of the ground and the grouting reaches the ground level, stop grouting to complete the construction.

[0022] Preferably, in step one, the grouting pipes are arranged along the axial direction of the steel pipe, and the grouting pipes are arranged in a circumferential array on the outer side of the steel pipe.

[0023] Preferably, the fixing frame includes a hoop and a support rod connected to the hoop. When fixing the precast bottom pile or precast pile unit, the hoop is clamped around the precast bottom pile or precast pile unit, and the lower end of the support rod is supported on the ground, so as to temporarily fix the precast bottom pile or precast pile unit.

[0024] Preferably, in step seven, in step one, the length of the steel pipe pressed into the soil and the total length are determined by the following steps:

[0025] It is known that the total length of the pile to be driven is L. Assuming that when the whole pile is constructed by the static pressure method, the corresponding total pressing force is F;

[0026] Take 1 / 2F as the total side friction resistance of the pressed steel pipe. This total side friction resistance can be used as the maximum uplift force that the pressed steel pipe 1 can provide, so as to achieve self-balanced pressing, and then calculate the length L1 of the steel pipe pressed into the soil inversely;

[0027] The length of the steel pipe above the ground is L2, then the total length of the steel pipe is L1 + L2;

[0028] The length of the precast pile that needs to be pressed into the bottom of the steel pipe is L - L1.

[0029] Preferably, flange plates are provided at the top end of the precast bottom pile and both ends of the precast pile unit, and bolt holes are provided on the flange plates; Pile splicing is carried out by means of flange plate connection.

[0030] Preferably, in step six, second bolt holes are provided on the pressure frame, and the second bolt holes correspond to the bolt holes on the flange plate; The pressure frame is horizontally placed at the upper end of the pile body, the second bolt holes on the pressure frame are aligned with the bolt holes on the flange plate at the upper end of the pile body, and the pressure frame is fixed to the upper end of the pile body by bolts.

[0031] Preferably, the pressure frame is a rectangular plate-like structure.

[0032] Preferably, in step seven, ear plate holes are provided on the pressure frame ear plate. After the steel strand passes through the ear plate holes on the pressure frame ear plate, it is closed to form a steel wire coil, and the hook on the winch unit locks the steel strand on the pressure frame, so as to realize the connection between the winch unit and the pressure frame.

[0033] Adopting the construction scheme provided by the present invention, compared with the prior art, it has the following characteristics and beneficial effects:

[0034] (1) Compared with the static pressure pile, the static pressure of the present invention is reduced by half, the construction speed is improved, and the construction cost is saved.

[0035] (2) Compared with the static drilling and root planting pile, the present invention effectively reduces the amount of drilled soil, avoids slurry wall protection, and the amount of cement slurry used is also correspondingly reduced, so as to achieve the effect of green environmental protection construction.

[0036] (3) The present invention combines the advantages of the static pressure pile and the static drilling and root planting pile processes, avoids their respective deficiencies, and has relatively good comprehensive technical benefits.

[0037] (4) Compared with the traditional method of pulling out the steel pipe, since the side friction resistance on the outer wall of the steel pipe reaches its limit value during the pile pressing process, it is relatively easy to pull out later. Description of the Drawings

[0038] Figure 1 It is a schematic diagram of the steel pipe required for partial hole leading provided by this solution.

[0039] Figure 2 It is a cross-sectional view of the steel pipe required for partial hole leading provided by this solution at the bolt hole.

[0040] Figure 3 It is a longitudinal sectional view of the steel pipe required for partial hole leading provided by this solution when initially pressed into the soil.

[0041] Figure 4 It is a longitudinal sectional view of the soil being taken out after the steel pipe required for partial hole leading provided by this solution is initially pressed into the soil.

[0042] Figure 5 It is a longitudinal sectional view of all the soil being taken out after the steel pipe required for partial hole leading provided by this solution is finally pressed into the soil.

[0043] Figure 6 It is a schematic diagram of a crane lifting a precast bottom pile.

[0044] Figure 7 It is a schematic diagram of a fixing frame fixing a precast bottom pile.

[0045] Figure 8 It is a schematic diagram of a crane lifting a precast pile unit.

[0046] Figure 9 It is a schematic diagram of connecting a precast pile unit to a precast bottom pile.

[0047] Figure 10 It is a schematic diagram of a fixing frame fixing a precast pile unit.

[0048] Figure 11 It is a schematic diagram of a crane lifting a precast pile unit.

[0049] Figure 12 It is a schematic diagram of connecting precast pile units.

[0050] Figure 13 It is a schematic diagram of connecting a precast pile to the bottom of the hole leading.

[0051] Figure 14 It is a schematic diagram of installing a machine base and a hoisting unit on the upper pipe wall of the steel pipe.

[0052] Figure 15 It is a schematic diagram of a hoisting machine hoisting a precast pile unit.

[0053] Figure 16 It is a schematic diagram of a fixing frame fixing the precast pile unit after pile connection.

[0054] Figure 17 It is a schematic diagram of a hoisting machine hoisting a pressure frame.

[0055] Figure 18 It is a three-dimensional view of the pressure frame provided by this solution.

[0056] Figure 19 It is a front and top view of the pressure frame provided by this solution.

[0057] Figure 20 It is a three-dimensional bottom view of the pressure frame provided by this solution.

[0058] Figure 21 It is a front sectional view of the hole part of the pressure frame provided by this solution.

[0059] Figure 22 It is a three-dimensional sectional view of the hole part of the pressure frame provided by this solution.

[0060] Figure 23 It is a schematic diagram of the connection between a winch unit and a pressure frame.

[0061] Figure 24 It is a schematic diagram of a precast pile being initially pressed into the soil.

[0062] Figure 25 It is a schematic diagram of a precast pile being finally pressed into the soil.

[0063] Figure 26 It is a schematic diagram of disconnecting the winch from the pressure frame.

[0064] Figure 27 It is a schematic diagram of all precast piles being pressed to the top of the steel pipe.

[0065] Figure 28 It is a schematic diagram of synchronous grouting during steel pipe extraction.

[0066] Figure 29 It is a schematic diagram of the overall situation after grouting is completed.

[0067] Figure 30 It is the overall process flow chart of the self-balanced construction method for partially pre-bored precast piles in this solution.

[0068] Attached drawing reference numerals: 1 - steel pipe; 2 - grouting pipe; 3 - first bolt hole; 4 - precast bottom pile; 5 - fixing frame; 6 - flange; 7 - precast pile unit; 8 - winch unit; 9 - machine base; 10 - pressure frame; 11 - pressure frame ear plate; 12 - second bolt hole; 13 - ear plate hole; 14 - bolt; 15 - hook; 16 - steel strand; 17 - power supply; 18 - mortar; 19 - mortar spray gun. Specific implementation mode

[0069] 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 belong to the scope of protection of the present invention. The overall flow chart of the solution is shown in Figure 30 as follows, and specifically includes the following implementation steps:

[0070] Step 1, press in the steel pipe: As Figure 1 shown, before the steel pipe 1 is pressed in, the grouting pipe 2 is arranged on the outer side of the steel pipe, and then the first bolt holes 3 are arranged on both sides of the upper part of the steel pipe 1. After the steel pipe 1 is pressed into the soil, the first bolt holes 3 on the steel pipe 1 are higher than the ground; the part of the steel pipe 1 pressed into the soil forms a precast pile; in the process of pressing the steel pipe 1 into the soil, the construction method of taking soil while pressing is adopted.

[0071] Among them, the length of the steel pipe 1 pressed into the soil and the total length are determined by the following steps:

[0072] 1.1 It is known that the total length of the pile body to be driven is L. Assuming that when the whole pile body is constructed by the static pressure method, the corresponding total pressing force is F;

[0073] 1.2 Take 1 / 2F as the total side friction resistance for pressing the steel pipe 1. This total side friction resistance can be used as the maximum uplift force that the steel pipe 1 can provide, so as to achieve self-balanced pressing, and thus the penetration length L1 of the steel pipe 1 is inversely calculated;

[0074] Among them, L1 can be calculated according to the total side friction resistance taken under the conditions. From fspa = π··i·si, where D is the diameter of the steel pipe and psi is the average penetration resistance of the i-th layer of soil.

[0075] 1.3 Assume that the length of the steel pipe 1 above the ground is L2 for the convenience of fixing the machine base 9 of the winch unit 8. Therefore, the total length of the steel pipe 1 is L1 + L2; the length of the steel pipe 1 above the ground, L2, can be determined according to the installation requirements of the winch unit 8 and the machine base 9, as long as the length L2 of the steel pipe 1 above the ground can meet the installation space of the winch unit 8 and the machine base 9.

[0076] 1.4 The length of the bottom of the steel pipe 1 that needs to be pressed into the soil is L - L1.

[0077] Among them, the grouting pipe 2 is arranged along the axial direction of the steel pipe 1. The first bolt holes 3 are arranged on both sides of the upper part of the steel pipe 1. The grouting pipes 2 are arranged on the outer side of the steel pipe 1 in an annular array. The grouting pipes 2 extend from the top to the bottom of the steel pipe 1.

[0078] Step 2: Making a partial pilot hole inside the steel pipe: Combining Figure 3 、 Figure 4 、 Figure 5 , since the soil inside the steel pipe 1 is cleared while the steel pipe 1 is being pressed into the soil by the method of taking soil while pressing, after all the soil inside the steel pipe 1 is taken out, a pilot hole is formed inside the steel pipe 1, and the pilot hole extends to the bottom of the steel pipe 1, as shown in Figure 5 .

[0079] Step 3: Hoisting the precast pile unit and splicing the pile to the bottom of the pilot hole: Specifically, it is divided into the following steps:

[0080] 3.1 As shown in Figure 6 , use a crane to hoist a precast bottom pile 4 to the upper part of the steel pipe 1. While slowly hoisting it into the steel pipe 1, ensure that the precast bottom pile 4 falls vertically; when the precast bottom pile 4 falls into the steel pipe 1 and the top of the precast bottom pile 4 just exceeds the top of the steel pipe 1, use a fixing frame 5 to temporarily fix the precast bottom pile 4, as shown in Figure 7 ;

[0081] 3.2 As shown in Figure 8 , use a crane to hoist the precast pile unit 7. While slowly and ensuring verticality, splice it to the precast bottom pile 4 fixed below, and use the construction method of connecting the piles through a flange 6; during pile splicing, make the coaxial connection between the precast bottom pile 4 and the precast pile unit 7;

[0082] 3.3 After pile splicing is completed, as shown in Figure 9 , loosen the fixing frame 5, and use a crane to slowly lower the spliced pile body. When the top of the pile body reaches the top position of the steel pipe 1, use a fixing frame 5 to temporarily fix the top of the pile body, as shown in Figure 10 ;

[0083] 3.4 Combining Figure 11 、 Figure 12 、 Figure 13 , repeat construction steps 3.2 and 3.3, and install the precast pile units 7 one by one at the upper end of the completed pile body until the lower end of the pile body reaches the bottom of the pilot hole, and ensure that the top of the pile body exceeds the top of the steel pipe 1.

[0084] In this step, the lower end of the precast bottom pile 4 is pointed, which is convenient for driving into the soil. The fixing frame 5 includes a hoop and a support rod connected to the hoop. When fixing the precast bottom pile 4 or the precast pile unit 7, the hoop is tightly held on the precast bottom pile 4 and the precast pile unit 7, and the lower end of the support rod is supported on the ground, so as to temporarily fix the precast bottom pile 4 or the precast pile unit 7. Flange plates 6 are provided at the top end of the precast bottom pile 4 and both ends of the precast pile unit 7, and bolt holes are provided on the flange plates 6; the connection between the precast pile units 7 or between the precast pile unit 7 and the precast bottom pile 4 is realized by means of flange connection; when splicing the piles, the flange plates 6 on two adjacent pile units are welded together, so as to realize the fixed connection between the pile units.

[0085] Step Four: Install the unit: As Figure 14 shown, the machine base 9 and the hoisting unit 8 are installed at the position of the first bolt hole 3 provided on the upper part of the steel pipe 1 by means of bolt connection; the machine base 9 is connected to the first bolt hole 3 on the upper part of the steel pipe 1 by bolts, and the hoisting unit 8 is installed on the machine base 9. In this application, there are two machine bases 9 and two hoisting machines 8, and the two machine bases 9 and the two hoisting machines 8 are respectively arranged on both sides of the upper part of the steel pipe 1.

[0086] Step Five: Splice the piles: Combining Figure 15 、 Figure 16 , the crane vertically hoists a precast pile unit 7 to the upper part of the steel pipe 1, and splices the pile with the top end of the pile body in the steel pipe 1 by means of flange plate 6 connection.

[0087] Step Six: Place the pressure frame: The specific method is as follows:

[0088] After Step Five is completed, as Figure 17 shown, use the crane to hoist the pressure frame 10 to the upper end of the pile body, and fix the pressure frame to the upper end of the pile body by bolts 14.

[0089] Among them, the structure of the pressure frame 10 is as Figures 18 - 22 shown, the pressure frame 10 is in a rectangular plate-like structure, and there are four second bolt holes 12 on the pressure frame 10, and the four second bolt holes 12 correspond to the bolt holes on the flange plate 6; the pressure frame 10 is horizontally placed at the upper end of the pile body, and the four second bolt holes on the pressure frame 10 are aligned with the bolt holes on the flange plate at the upper end of the pile body, and the pressure frame 10 is fixed to the upper end of the pile body by bolts 14. There are two pressure frame ear plates 11 below the pressure frame 10, and the pressure frame ear plates 11 are arranged on both sides of the pressure frame 10. There are ear plate holes 13 on the pressure frame ear plates 11.

[0090] Step Seven: Connect the hoisting unit and the pressure frame: As Figure 23As shown, on each of the gusset plates 11 on both sides below the pressure frame 10, there are gusset plate holes 13. The two gusset plates 11 on both sides below the pressure frame are connected to the hoist units 8 on both sides of the upper part of the steel pipe 1 through steel strands 16.

[0091] When connecting, the steel strand 16 passes through the gusset plate hole 13 on the gusset plate 11 and then closes to form a steel wire coil. The hook 15 on the hoist unit 8 hooks and locks the steel strand 16 on the pressure frame 10, thus realizing the connection between the hoist unit 8 and the pressure frame 10.

[0092] Step Eight: Start the hoist unit: As Figure 24 shown, connect the hoist unit 8 to the power supply 17, and supply power to the hoist unit 8 through the power supply 17; turn on the power supply 17, and slowly and uniformly start the hoist unit 8, so that the hoist units 8 on both sides of the upper part of the steel pipe 1 pull the pressure frame 10 to move downward at the same speed, and make the pressure frame 10 press the pile body into the soil until the pile body is pressed into the set depth; during this process, continuously monitor the verticality of the precast pile unit.

[0093] Step Nine: Disconnect the connection between the unit and the pressure frame: As Figure 25 shown, when the pile body is pressed into the set depth, at this time, part of the uppermost precast pile unit 7 is higher than the top of the steel pipe 1; disconnect the power supply 17, remove the hook 15, and after removing the bolts 14 connecting the pressure frame 10 and the end flange 6 of the precast pile, the crane lifts the pressure frame 10 and disconnects the connection between the hoist unit 8 and the pressure frame 10, as Figure 26 shown.

[0094] Step Ten: Repeat the steps: Repeat Steps Five to Nine until all the precast pile units 7 are pressed into the steel pipe 1.

[0095] Step Eleven: Pull out the steel pipe and grout synchronously, and the specific steps are as follows:

[0096] 11.1 Combine Figure 27 , Figure 28 , remove the machine base 9 and the hoist unit 8 on the steel pipe 1, and place the mortar spray guns 19 in each grouting pipe 2 respectively;

[0097] 11.2 As Figure 28 shown, slowly and uniformly pull out the steel pipe 1 with a crane, and at the same time grout the empty space after the steel pipe 1 is pulled out.

[0098] 11.3 Wait until the steel pipe 1 is completely pulled out of the ground, stop grouting after grouting to be flush with the ground, and finally conduct the verticality detection of the pile body to complete the construction, as Figure 29 shown.

[0099] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience 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 orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0100] It can be understood that the term "a" should be construed as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. The term "a" should not be construed as limiting the quantity.

[0101] Although professional terms are used more frequently herein, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0102] The present invention is not limited to the above best embodiments. Anyone can obtain other various forms of products under the inspiration of the present invention. However, regardless of any changes in its shape or structure, as long as it has a technical solution identical or similar to that of the present application, it falls within the protection scope of the present invention.

Claims

1. A self-balanced pressing construction method for partially pre-drilled precast piles, characterized in that It includes the following steps: Step 1, press in the steel pipe: Lay the grouting pipe (2) outside the steel pipe (1), and then set the first bolt holes (3) on both sides of the upper part of the steel pipe (1); Press the steel pipe (1) into the soil, and make the first bolt holes (3) on the steel pipe (1) higher than the ground; The length of the steel pipe (1) pressed into the soil and the total length are determined by the following steps: It is known that the total length of the pile to be driven is L. Assume that when the whole pile is constructed by the static pressure method, the corresponding total pressing force is F; Take 1 / 2F as the total side friction resistance for pressing the steel pipe (1). This total side friction resistance can be used as the maximum uplift force that the pressed-in steel pipe can provide, so as to achieve self-balanced pressing, and then inversely calculate the length L1 of the steel pipe (1) pressed into the soil; The length of the steel pipe (1) above the ground is L2, then the total length of the steel pipe (1) is L1 + L2; The length of the precast pile to be pressed into the bottom of the steel pipe (1) is L - L1; Step 2, after all the soil in the steel pipe (1) is taken out, form a pilot hole in the steel pipe (1), and the pilot hole reaches the bottom of the steel pipe (1); Step 3, hoist the precast pile unit and connect the piles to the bottom of the pilot hole. The steps are as follows: S1: Use a crane to hoist a precast bottom pile (4) and lift it into the steel pipe (1); When the precast bottom pile (4) falls into the steel pipe (1) and the top just exceeds the top of the steel pipe (1), temporarily fix the precast bottom pile (4) with a fixing frame (5); S2: Hoist the precast pile unit (7) by the crane and connect the precast pile unit (7) to the top of the precast bottom pile (4); S3: Loosen the fixing frame (5), use the crane to lower the connected pile body. When the top of the pile body falls to the top position of the steel pipe (1), temporarily fix the top of the pile body with the fixing frame (5); S4: Repeat the construction steps S2 and S3, and successively install the precast pile units (7) on the upper end of the completed pile body until the lower end of the pile body reaches the bottom of the pilot hole; Step 4, install the unit: Install the machine base (9) at the position of the first bolt holes (3) provided on the upper part of the steel pipe (1) by means of bolt connection, and install the hoist unit (8) on the machine base (9); Step 5, connect the piles: The crane hoists a precast pile unit (7) and connects the precast pile unit (7) to the top of the completed pile body; Step 6, place the pressure frame (10): Hoist the pressure frame (10) to the upper end of the pile body by the crane, and fix the pressure frame to the upper end of the pile body with bolts (14); Step 7, connect the hoist unit (8) and the pressure frame (10): Connect the two pressure frame ear plates (11) on both sides below the pressure frame (10) to the hoist unit (8) on both sides of the upper part of the steel pipe (1) through steel strands (16); Step 8, start the hoist unit (8): Connect the hoist unit (8) to the power supply (17), turn on the power supply (17) and start the hoist unit (8), so that the hoist units (8) on both sides of the upper part of the steel pipe (1) pull the pressure frame (10) to move downward at the same speed, and press the pile body into the soil through the pressure frame (10) until the pile body is pressed into the set depth; Step 9: Disconnect the connection between the hoisting unit (8) and the pressure frame (10), remove the bolts (14) connecting the pressure frame (10) to the top of the pile body, and move the pressure frame (10) away from the top of the pile body; Step 10: Repeat Steps 5 to 9 until all precast pile units (7) are pressed into the steel pipe (1); Step 11: Pull out the steel pipe and grout synchronously: Remove the pedestal (9) and the hoisting unit (8) on the steel pipe (1), and place the mortar spray guns (19) into the respective grouting pipes (2); Slowly and evenly pull out the steel pipe (1) with a crane, and at the same time grout the empty space after the steel pipe (1) is pulled out; When the steel pipe (1) is completely pulled out of the ground and the grouting reaches the ground level, stop grouting to complete the construction.

2. The self-balanced pressing construction method of the partially pre-bored precast pile according to claim 1, characterized in that, In Step 1, the grouting pipes (2) are arranged along the axial direction of the steel pipe (1), and the grouting pipes (2) are arranged in a circular array on the outside of the steel pipe (2).

3. The self-balanced pressing construction method of partially pre-bored precast piles according to claim 1, characterized in that The fixing frame (5) includes a hoop and support rods connected to the hoop. When fixing the precast bottom pile (4) or the precast pile unit (7), the hoop is tightened around the precast bottom pile (4) or the precast pile unit (7), and the lower ends of the support rods are supported on the ground, thereby temporarily fixing the precast bottom pile (4) or the precast pile unit (7).

4. The self-balanced pressing construction method for partially pre-bored precast piles according to claim 1, characterized in that, Flange plates (6) are provided at the top end of the precast bottom pile (4) and at both ends of the precast pile unit (7), and bolt holes are provided on the flange plates; Pile splicing is carried out by means of flange plate connection.

5. The method for self-balanced pressing construction of partially pre-bored precast piles according to claim 4, characterized in that, In Step 6, second bolt holes (12) are provided on the pressure frame (10), and the second bolt holes (12) correspond to the bolt holes on the flange plate (6); The pressure frame (10) is horizontally placed at the upper end of the pile body, the second bolt holes (12) on the pressure frame (10) are aligned with the bolt holes on the flange plate (6) at the upper end of the pile body, and the pressure frame (10) is fixed to the upper end of the pile body by bolts (14).

6. The self-balanced pressing construction method of partially pre-bored precast piles according to claim 1, characterized in that, The pressure frame (10) is of a rectangular plate-like structure.

7. The self-balanced pressing construction method of partially pre-bored precast piles according to claim 1, characterized in that, In Step 7, ear plate holes (13) are provided on the pressure frame ear plate (11), the steel strand (16) passes through the ear plate holes (13) on the pressure frame ear plate (11) and then closes to form a steel wire coil, and the hook (15) on the hoisting unit (8) hooks the steel strand (16) on the pressure frame (10), thereby realizing the connection between the hoisting unit (8) and the pressure frame (10).

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