Drilling and grouting integrated screw pile foundation construction method

Abstract

The invention discloses a drilling and grouting integrated screw pile foundation construction method which uses a screw pile to form a screw pile foundation and comprises the steps that the screw pile comprises a pile disc and a grout spraying opening, the grout spraying opening is formed in the upper end of the pile disc in the radial direction, the screw pile is rotated so that the screw pile can spirally penetrate into a soil body downwards, and in the spiral downward penetrating process of the screw pile, the grout spraying opening is formed in the pile disc. And slurry is injected into the spiral pile, the slurry is sprayed out from the slurry spraying opening and is sprayed into the groove, so that the slurry flows along the spiral path of the groove, the groove is formed by the hole wall of the broken hole of the pile disc, and the spiral path of the groove is a rotary moving path formed by the hole wall of the broken hole of the pile disc. While the uplift bearing capacity or the compression bearing capacity of the screw pile is improved, the material and construction cost is reduced, and the compactness of a soil body is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation construction methods, and specifically to an integrated drilling and grouting spiral pile foundation construction method. Background Art

[0002] The spiral pile foundation is an important pile foundation and is widely used in geotechnical engineering such as transmission and transformation line projects, wind power, photovoltaic power generation, and pipeline foundations. In order to improve the uplift bearing capacity or compressive bearing capacity of the spiral pile, multiple pile disks are added to the spiral pile foundation. During the construction of the spiral pile foundation, a certain torque and / or pressure need to be applied to the spiral pile foundation to screw the spiral pile into the soil mass. Such construction of the spiral pile foundation means that for each additional pile disk, due to the need to overcome the additional friction between the spiral pile foundation and the soil mass, the torque needs to be increased. Thus, when the number of spiral pile disks is relatively large, it is often difficult to find a matching torque construction device that can apply a large torque, resulting in an obstacle to the application of spiral piles. In addition, when the number of pile disks is relatively large, the construction of the spiral pile foundation will increase the disturbed area of the soil mass and reduce the density of the soil mass, thereby reducing the uplift bearing capacity or compressive bearing capacity of the spiral pile to a certain extent.

[0003] Most of the spiral drills / spiral drilling rigs retrieved by the applicant adopt a relatively long pile disk, which spirally winds from one end of the pile body and extends to the other end close to the pile disk, and the slurry spraying ports for slurry output are often arranged on the outer side in the radial direction of the pile disk and arranged along the spiral direction of the pile disk, or directly arranged on the pile body and arranged along the axial direction of the pile body. For example, in the Chinese utility model patent with the publication number CN203188200U retrieved by the applicant, the spraying holes are arranged on the outer wall of the drill pipe and distributed along the axial direction of the drill pipe.

[0004] As Figure 1 shown, for the spiral drill / spiral drilling rig with such an arrangement of slurry spraying holes, when using this spiral drill for construction, the slurry ejected from the slurry spraying port will be sprayed on the surface of the soil hole wall penetrated by the spiral drill, and the slurry will flow downward along the surface of the soil hole wall under the action of gravity to cover the surface of the soil hole wall. Figure 1 What is shown by the red frame in

[0005] is the result of the slurry being sprayed on the surface of the soil hole wall and flowing downward along the surface of the soil hole wall. Based on such a spiral drill after construction by grouting, the slurry cannot enter the interior of each layer of soil, but can only be sprayed on the hole wall surface of the hole to reinforce the hole wall to prevent collapse.

[0006] At present, in order to improve the uplift bearing capacity or compressive bearing capacity of traditional screw piles, the number of pile plates or the diameter of the pile plates is usually increased, which increases the steel cost. Moreover, the more the number of pile plates and the larger the diameter of the pile plates, the more mechanical equipment with a larger installation torque is required for construction, increasing the construction cost. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a construction method for a drilling and grouting integrated screw pile foundation, which can solve the problems described in the background technology.

[0008] The technical solution to achieve the purpose of the present invention is: a construction method for a drilling and grouting integrated screw pile foundation, using a screw pile to form the screw pile foundation, including,

[0009] The screw pile includes a pile plate and a slurry injection port, and the slurry injection port is arranged radially along the upper end of the pile plate.

[0010] Rotate the screw pile so that the screw pile spirally penetrates downward into the soil body. During the process of the screw pile spirally penetrating downward, inject slurry into the screw pile. The slurry is ejected from the slurry injection port and ejected into the groove, so that the slurry flows along the spiral path of the groove. The groove is formed by the hole wall of the broken hole of the pile plate, and this spiral path of the groove is the rotational movement path formed by the hole wall of the broken hole of the pile plate.

[0011] Further, rotate the screw pile so that the screw pile spirally penetrates downward into the soil body. During the process of the screw pile spirally penetrating downward, inject slurry into the screw pile. The slurry is ejected from the slurry injection port and ejected into the groove, so that the slurry flows along the spiral path of the groove. The groove is formed by the hole wall of the broken hole of the pile plate, and this spiral path of the groove is the rotational movement path formed by the hole wall of the broken hole of the pile plate. Its specific implementation process includes the following steps:

[0012] Step S1: Apply torque and downward pressure to the screw pile to make the screw pile enter the soil body;

[0013] Step S2: When the pile plate on the screw pile completely enters the soil body, rotate the screw pile one more week, and then start grouting.

[0014] The slurry injection port is arranged radially along the upper end of the pile plate, so that the slurry ejected from the slurry injection port is ejected along the spiral path of the pile plate breaking the soil body into the spiral groove on the hole wall of the soil body.

[0015] Step S3: While rotating the screw pile to increase the grouting depth, inject slurry at the same time. When the screw pile reaches the designed depth, stop rotating the screw pile. After stopping grouting, the construction of the screw pile foundation is completed.

[0016] Further, before step S1, the following steps are also included:

[0017] Step S1-1: Analyze the soil type, density, and groundwater level, and determine the length of the screw pile and the spiral pitch of the pile disk based on the analysis results of the soil type, density, and groundwater level.

[0018] Further, after step S1-1 and before step S1, the following steps are also included:

[0019] Step S1-2: Determine the setting method of the end of the pile disk of the screw pile based on the function of the screw pile.

[0020] Further, after step S1-2 and before step S1, the following steps are also included:

[0021] Step S1-3: Adjust the parameters of the screw pile to ensure that the slurry can flow normally and spray out from the slurry injection port. The parameters of the screw pile include the pressure and flow rate parameters of the high-pressure pump, grouting pipe, and slurry injection port.

[0022] Further, in step S2, the grouted slurry is cement slurry prepared according to a preset water-cement ratio.

[0023] Further, the water-cement ratio is 1:1 - 1.5:1.

[0024] Further, before step S1, the following steps are also included:

[0025] Use a theodolite or total station to correct the position and verticality of the anchor rod. The screw pile is constructed at the position of the anchor rod along this verticality, and torque and downward pressure are applied to the screw pile.

[0026] Further, an external torsion application device is used to apply torsional force and downward pressure to the load transfer device on the screw pile to apply torque and downward pressure to the screw pile.

[0027] Further, in step S3, after stopping the rotation of the screw pile, the following is also included,

[0028] Continue grouting until the slurry overflows and then stop grouting, thus completing the construction of the screw pile foundation.

[0029] Advantages of the present invention: While improving the uplift bearing capacity or compressive bearing capacity of the screw pile, the present invention reduces material and construction costs and enhances soil density. Description of the Drawings

[0030] Figure 1 It is a schematic diagram after the grouting effect of the construction of the traditional screw pile foundation acts on the hole wall;

[0031] Figures 2 - 5 It is a schematic diagram of the structure of the screw pile foundation from different visual angles;

[0032] Figure 6 Schematic diagram of the formed screw pile foundation

[0033] Figure 7 including Figure 1 Schematic diagram for comparison with the simulation of the penetration of the screw pile of this embodiment into the soil. The right half of the figure is the simulation schematic diagram of the penetration of the screw pile of this embodiment into the soil. The yellow in the figure represents the soil, and the gray spiral shape is the screw pile foundation formed by using the screw pile. The left half is Figure 1 ;

[0034] In the figure, 1 - load transfer device, 2 - fixing part, 21 - transverse rod, 22 - inclined rod, 3 - slurry pipe joint, 4 - partition piece, 5 - pile body, 51 - pile body column, 52 - pile body tip, 6 - pile plate, 7 - slicing head, 8 - slurry injection port, 9 - fixing ring, 10 - slurry pipe, 11 - connecting rod, 12 - sleeve, 13 - rotary joint Specific implementation mode

[0035] The following further describes the present invention in conjunction with the attached drawings and specific implementation schemes

[0036] As Figures 2 - 7 shown, a construction method for an integrated drilling and grouting screw pile foundation includes the following steps

[0037] Step 1: Analyze the soil type, density and groundwater level, and determine parameters such as the length of the screw pile and the spiral pitch of the pile plate 6 based on the analysis results of the soil type, density and groundwater level

[0038] The length of the screw pile in this embodiment is characterized by the number of turns of the screw pile, 1 ≤ the number of turns of the screw pile < 2

[0039] In this step, at the target construction site where the screw pile foundation needs to be formed, analyze the soil type, density and groundwater level of the site, so as to determine the screw pile with the corresponding length and spiral intercept, and carry out grouting construction based on this screw pile to obtain the screw pile foundation at the target construction site

[0040] Step 2: If the screw pile is mainly used for uplift resistance, the tail end of the pile plate 6 of the screw pile is tilted upward; if the screw pile is used for compression resistance, the tail end of the pile plate 6 of the screw pile is tilted downward

[0041] It can be understood that during the construction process of the screw pile, it generally plays two roles, namely uplift resistance and compression resistance. When the role of uplift resistance is greater than that of compression resistance, it can be considered that it is mainly used for uplift resistance. When the role of compression resistance is greater than that of uplift resistance, it can be considered that it is mainly used for compression resistance

[0042] It can also be understood that according to whether the function is anti-pulling or anti-compression, corresponding screw piles with the end tilted upward or the end tilted downward set in advance (produced) can be selected, or it can be set by structurally arranging movable connections and temporarily adjusting the end of the pile plate 6 to tilt upward or downward on-site according to the function. That is, the end of the pile plate 6 is movably installed and can be adjusted to tilt upward or downward, or different screw piles with the end tilted upward or downward can be produced, and the corresponding screw pile can be selected according to the usage requirements.

[0043] Step 3: Calibrate and adjust the pressure and flow parameters of equipment such as the high-pressure pump, grouting pipe, and grout spraying nozzle 8 to ensure good sealing of the pipeline for the slurry flow, prevent blockage, so as to ensure that the slurry can flow normally and spray out from the grout spraying nozzle 8 to complete the grouting operation.

[0044] Step 4: Prepare cement slurry as the slurry according to the preset water-cement ratio, and the water-cement ratio is usually 1:1 - 1.5:1.

[0045] Step 5: Use a theodolite or total station or other equipment to correct the position and verticality of the anchor rod.

[0046] Step 6: The screw pile is constructed at the position of the anchor rod and along this verticality, applying torque and downward pressure to the screw pile to make the screw pile enter the soil body. The anchor rod is only allowed to rotate in one direction, for example, only clockwise rotation, that is, the anchor rod rotates clockwise throughout the construction process to avoid disturbing the undisturbed soil.

[0047] It can be understood that a torsional force and a downward pressure can be applied to the load transfer device 1 on the screw pile through an external torsional force applying device, so as to apply torque and downward pressure to the screw pile.

[0048] Step 7: When the pile plate 6 on the screw pile completely enters the soil body, rotate the screw pile one more week, that is, rotate the screw pile one circle, and then start grouting, that is, pour the cement slurry as the slurry into the slurry conveying device on the screw pile, and the slurry finally sprays out from the grout spraying nozzle 8.

[0049] The grout spraying nozzle 8 is arranged along the radial direction at the upper end of the pile plate 6, so that the slurry sprayed out from the grout spraying nozzle 8 can be sprayed into the spiral groove on the soil body hole wall along the spiral path of the pile plate 6 breaking the soil body. The slurry is mixed with the soil particles in the soil body, and after the slurry solidifies, it can form a consolidated screw pile foundation with the soil body, thus forming a screw pile foundation in the spiral groove.

[0050] Compared with traditional screw piles, since the slurry spraying orifice 8 is arranged along the radial direction of the pile plate 6, during the process of the pile plate 6 breaking through the soil hole wall to form a groove, the slurry ejected from the slurry spraying orifice 8 is directly sprayed onto the groove. And as the screw pile is screwed into the soil downward, the pile plate 6 forms a spiral groove path, and the slurry flows along this spiral groove path, thereby forming a screw pile foundation, which increases the uplift bearing capacity or compressive bearing capacity of the screw pile foundation. In addition, the pile plate 6 does not need to be arranged along the axial direction of the pile body 5 for a long length as in the traditional case, that is, there is no need to arrange multiple turns of the pile plate 6, and only one turn of the pile plate 6 needs to be arranged. Of course, in actual use, it is also feasible to arrange multiple turns of the pile plate 6. Arranging one turn of the pile plate 6 reduces the number of pile plates 6, thereby reducing the disturbance to the soil and reducing the construction cost.

[0051] Step 8: Rotate the screw pile while increasing the grouting depth, and grout at the same time. When the screw pile reaches the designed depth, stop rotating the screw pile and continue grouting until it is found that the slurry overflows and then stop grouting, thereby completing the construction of the screw pile foundation.

[0052] In order to implement the above construction method of the integrated drilling and grouting screw pile foundation, the present invention also provides an integrated drilling and grouting screw pile foundation structure, and using this screw pile foundation structure can implement the above construction method of the integrated drilling and grouting screw pile foundation.

[0053] The screw pile foundation structure includes a pile body 5, and a pile plate 6, a slurry conveying device, and a load transfer device 1 arranged on the pile body 5. The load transfer device 1 is arranged on the outer wall at the upper end of the pile body 5. The pile plate 6 is provided with a slurry spraying orifice 8, and the slurry conveying device is connected to the slurry spraying orifice 8 in a communicating manner, so that slurry can be poured into the slurry spraying orifice 8 through the slurry conveying device, and the slurry is sprayed out from the slurry spraying orifice 8 to the outside to achieve grouting.

[0054] The pile plate 6 spirally surrounds the outer wall of the pile body 5, and 1 ≤ the number of spiral turns of the pile plate 6 < 2, that is, the number of spiral turns of the pile plate 6 is at least 1 turn and cannot exceed 2 turns. On the premise of satisfying the formation of the screw pile foundation structure, the length of the pile plate 6 is reduced as much as possible, so as to avoid disturbing the soil and improve the uplift bearing capacity or compressive bearing capacity.

[0055] It can be understood that the above limitation of the number of spiral turns of the pile plate 6 within the range of 1 - 2 turns is for the purpose of not setting too many turns, so as to avoid excessive torque caused by too many pile plates 6 or too long length. Therefore, in actual situations, the number of turns can also be appropriately increased according to the situation, for example, exceeding two turns and limited within 2 - 3 turns. It is more appropriate to set the number of spiral turns of the pile plate 6 within the range of [1, 2).

[0056] The slurry spraying orifice 8 is arranged at the end edge along the radial direction at the upper end of the pile plate 6, and multiple slurry spraying orifices 8 can be arranged and distributed along the radial direction. Refer to Figure 2, the slurry spraying ports 8 are arranged at the uppermost end of the pile plate 6 along the radial direction away from the pile body 5, that is, arranged at the side (not the outer edge) of the upper end of the pile plate 6, and a plurality of slurry spraying ports 8 are arranged at intervals.

[0057] One end of the slurry conveying device extends into the pile plate 6 and is connected and communicated with the slurry spraying ports 8.

[0058] As Figure 6 shown, the slurry spraying ports 8 are arranged at the end edge along the radial direction of the upper end of the pile plate 6, so that during the process of the pile body 5 spirally penetrating into the soil, the pile plate 6 breaks through the hole wall of the hole and forms strip-shaped grooves on the hole wall. The grooves are spiral. The slurry spraying ports 8 rotate and move downward following the pile plate 6, so that the slurry spraying ports 8 move along the spiral grooves, and the slurry sprayed from the slurry spraying ports 8 is sprayed into the grooves, thereby forming a spiral pile foundation.

[0059] Exemplarily, a slicing head 7 is connected to the end edge along the radial direction of the lower end of the pile plate 6. The slicing head 7 gradually decreases in radial thickness away from the pile body 5, that is, thicker inside and thinner outside, and the slicing head 7 gradually increases in thickness along the spiral ascending direction, that is, the outer side edge is thinner. Such a slicing head 7 is beneficial to break through the soil, thereby forming the grooves of the spiral pile.

[0060] It can be understood that the slicing head 7 and the pile plate 6 can be an integral structure.

[0061] Exemplarily, a fixing ring 9 is also connected to the end edge along the radial direction of the upper end of the pile plate 6. The fixing ring is detachably or fixedly sleeved on the pile plate 6, and the slurry spraying ports 8 extend from the pile plate 6 and are arranged on the fixing ring 9.

[0062] Exemplarily, the pile body 5 includes a pile body column 51 and a pile body pointed head 52. The pile body pointed head 52 is fixed at one end of the pile body column 51. The pile body pointed head 52 and the pile body column 51 can be an integral structure. The pile plate 6 spirally surrounds the pile body column 51. One end of the pile body pointed head 52 away from the pile body column 51 is pointed.

[0063] The pile body column 51 is a column with a cavity. The pile body pointed head 52 is a solid structure or the pile body 5 does not have a pile pointed head. When the pile body 5 does not have a pile pointed head, a partition sheet 4 is also arranged in the cavity of the pile body column 51. The partition sheet 4 divides the cavity into two parts. One cavity is communicated with the pile body pointed head 52, and the other cavity is isolated from the pile body pointed head 52 and not communicated. The slurry conveying device is located in the cavity isolated from the pile body pointed head 52, so as to avoid damage to the slurry conveying device caused by soil extrusion during the rotation and sinking process of the spiral pile.

[0064] Exemplarily, the slurry delivery device includes a slurry delivery pipe joint 3, a rotary joint 13 and a slurry delivery pipe 10. The slurry delivery pipe joint 3 is plugged into the rotary joint 13 and connected to the rotary joint 13. The rotary joint 13 is connected to the slurry delivery pipe 10. One end of the slurry delivery pipe 10 extends into the pile plate 6 and is connected to the grouting port 8. The rotary joint 13 includes an upper rotating head and a lower rotating head. The upper rotating head and the lower rotating head are sleeved and rotatably connected, so that the upper rotating head and the lower rotating head can rotate relative to each other. The slurry delivery pipe joint 3 is connected to the upper rotating head, and the slurry delivery pipe 10 is connected to the lower rotating head. Through the relatively rotatable upper rotating head and the lower rotating head, when the pile body 5 rotates and penetrates into the soil, the slurry delivery pipe 10 and the lower rotating head rotate with the pile body 5, and the upper rotating head remains fixed and rotates relative to the lower rotating head, thereby avoiding twisting the slurry delivery device into a twisted shape, so that the external slurry injection device can be well connected to the slurry delivery pipe 10 structure.

[0065] Exemplarily, the slurry delivery device further includes a first fixing member 2 and a second fixing member, one end of the first fixing member 2 is connected to the rotary joint 13, and can be connected to the upper rotary head or the lower rotary head to fix the rotary joint 13, and the other end of the first fixing member 2 is fixedly connected to the inner wall of the cavity of the pile body 5. One end of the second fixing member is connected to the slurry delivery pipe 10, and the other end is fixedly connected to the inner wall of the cavity of the pile body 5. The second fixing member is located below the first fixing member.

[0066] Exemplarily, the first fixing member 2 includes a transverse rod 21 and an oblique rod 22, one end of the transverse rod 21 is connected to the rotary joint 13, and the other end of the transverse rod 21 is fixedly connected to the inner wall of the cavity of the pile body 5, one end of the oblique rod 22 is connected to the transverse rod 21, and the other end is fixedly connected to the inner wall of the cavity of the pile body 5, and the oblique rod 22 is obliquely arranged below the transverse rod, and the oblique rod serves to enhance support.

[0067] Exemplarily, the second fixing member includes a connecting rod 11 and a sleeve 12 . The sleeve 12 is sleeved on the slurry delivery pipe 10 . One end of the connecting rod 11 is connected to the sleeve 12 , and the other end of the connecting rod 11 is fixedly connected to the inner wall of the cavity of the pile body 5 .

[0068] The load transfer device 1 is a block structure, and is provided with a plurality of load transfer devices 1. Each load transfer device 1 is arranged around the pile body 5 at intervals along the circumference. A notch is provided on one side of the load transfer device 1. The notch is provided to facilitate the torsion process of the state. The external torsion device that applies torque and downward pressure can be easily aligned with the load transfer device 1 through the notch, and the connection is not easy to fall off, so a stable connection is maintained.

[0069] The present invention improves the pull-out bearing capacity or the compressive bearing capacity of the screw pile, reduces the material and construction costs, and enhances the soil density.

[0070] The embodiments disclosed in this specification are only an illustration of the unilateral features of the present invention. The protection scope of the present invention is not limited to this embodiment, and any other functionally equivalent embodiments fall within the protection scope of the present invention. For those skilled in the art, various corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A construction method for an integrated drilling and grouting screw pile foundation, using screw piles to form the screw pile foundation, characterized in that, including, The screw pile includes a pile plate and a slurry injection port. The slurry injection port is arranged radially at the upper end of the pile plate. Rotate the screw pile so that the screw pile spirally penetrates into the soil downward. During the process of the screw pile spirally penetrating into the soil downward, inject slurry into the screw pile. The slurry is ejected from the slurry injection port and ejected into the groove, so that the slurry flows along the spiral path of the groove. The groove is formed by the hole wall of the broken hole of the pile plate, and the spiral path of the groove is the rotational movement path formed by the hole wall of the broken hole of the pile plate.

2. The construction method of the integrated drilling and grouting screw pile foundation according to claim 1, characterized in that, Rotate the screw pile so that the screw pile spirally penetrates into the soil downward. During the process of the screw pile spirally penetrating into the soil downward, inject slurry into the screw pile. The slurry is ejected from the slurry injection port and ejected into the groove, so that the slurry flows along the spiral path of the groove. The groove is formed by the hole wall of the broken hole of the pile plate, and the spiral path of the groove is the rotational movement path formed by the hole wall of the broken hole of the pile plate. The specific implementation process includes the following steps: Step S1: Apply torque and downward pressure to the screw pile to make the screw pile enter the soil. Step S2: When the pile plate on the screw pile completely enters the soil, rotate the screw pile one more turn, and then start grouting. The slurry injection port is arranged radially at the upper end of the pile plate, so that the slurry ejected from the slurry injection port is ejected along the spiral path of the pile plate breaking the soil into the spiral groove on the soil hole wall. Step S3: Rotate the screw pile while grouting to increase the grouting depth. When the screw pile reaches the designed depth, stop rotating the screw pile. After stopping grouting, the construction of the screw pile foundation is completed.

3. The construction method of the integrated drilling and grouting spiral pile foundation according to claim 2, characterized in that, Before step S1, the following steps are also included: Step S1-1: Analyze the soil type, density and groundwater level, and determine the length of the screw pile and the spiral pitch of the pile plate based on the analysis results of the soil type, density and groundwater level.

4. The construction method of the integrated drilling and grouting spiral pile foundation according to claim 3, characterized in that, After step S1-1 and before step S1, the following steps are also included: Step S1-2: Determine the setting method of the tail end of the pile plate of the screw pile based on the function of the screw pile.

5. The construction method of the integrated drilling and grouting spiral pile foundation according to claim 4, characterized in that After step S1-2 and before step S1, the following steps are also included: Step S1-3: Adjust the parameters of the screw pile to ensure that the slurry can flow normally and be ejected from the slurry injection port. The parameters of the screw pile include the pressure and flow rate parameters of the high-pressure pump, grouting pipe and slurry injection port.

6. The construction method of the integrated drilling and grouting spiral pile foundation according to any one of claims 1-5, characterized in that In step S2, the grouting slurry is the cement slurry prepared according to the preset water-cement ratio.

7. The construction method of the integrated drilling and grouting spiral pile foundation according to claim 6, characterized in that, The water-cement ratio is 1:1 - 1.5:

1.

8. The construction method of the integrated drilling and grouting spiral pile foundation according to any one of claims 1-5, characterized in that Before step S1, the following steps are also included: Use a theodolite or total station to correct the position and verticality of the anchor rod. The screw pile is constructed at the position of the anchor rod and along this verticality, and torque and downward pressure are applied to the screw pile.

9. The construction method of the integrated drilling and grouting spiral pile foundation according to claim 8, characterized in that, Use an external torsion application device to apply torsion force and downward pressure to the load transfer device on the screw pile to apply torque and downward pressure to the screw pile.

10. The construction method of the integrated drilling and grouting spiral pile foundation according to any one of claims 1-5, characterized in that, In step S3, after stopping rotating the screw pile, it also includes Continue grouting until the slurry overflows and then stop grouting, so as to complete the construction of the screw pile foundation.

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