A miniature steel pipe pile tower foundation and its construction method

Abstract

This invention discloses a micro-steel pipe pile tower foundation and its construction method, comprising a micro-steel pipe installed in a pile hole, the micro-steel pipe being filled with cement mortar, a ground platform connected to the top of the micro-steel pipe, and multiple overflow ports symmetrically opened at the bottom of the micro-steel pipe, each of which is hinged with a compression mechanism for forming an enlarged head at the pile end; a prestressing application mechanism, the bottom of which is drivenly connected to the multiple compression mechanisms, and the top of which is fixedly connected to the ground platform. This invention improves the horizontal bearing capacity through the prestressing application mechanism and, through the compression of the compression mechanisms, integrally forms an enlarged head with the cement mortar, thereby improving the pull-out bearing capacity. This achieves an overall improvement in the performance of the micro-steel pipe pile tower foundation, offering the beneficial effects of increased construction efficiency, reduced labor intensity, and lower operational risks.

Description

Technical Field

[0001] This invention relates to the field of pole and tower foundation technology, and more specifically, to a miniature steel pipe pile pole and tower foundation and its construction method. Background Technology

[0002] Due to the limitations of the terrain, large construction machinery is difficult to use, so most power transmission line foundations in high-altitude mountainous areas still rely on manually excavated boreholes. However, the low-pressure, low-oxygen, and low-temperature working environment in high-altitude areas makes it difficult for workers to adapt, resulting in extremely low efficiency. Furthermore, manually excavated boreholes require significant depths, posing substantial safety risks to workers during excavation. Therefore, there is an urgent need to develop a novel micro-steel pipe pile tower foundation technology suitable for mechanized construction in high-altitude mountainous areas, thereby reducing construction safety risks and labor intensity while improving construction efficiency.

[0003] Miniature steel pipe pile foundations are a new type of foundation developed from rock anchor foundations and miniature concrete pile foundations, combining the advantages of both and offering wider applicability. Compared to ordinary rock anchor foundations, steel pipe piles have a larger bonding surface and better bonding performance. The steel pipes can also withstand greater horizontal forces, exhibiting the characteristics of "small diameter, high strength." The diameter and wall thickness of the steel pipe piles are more flexible, ranging from 80 to 350 mm in diameter and 4 to 25 mm in wall thickness, allowing for the selection of appropriate specifications based on the stress conditions. Miniature steel pipe pile foundations can utilize small-scale mechanical drilling, eliminating the need to transport air compressors to the tower site, resulting in shorter construction time and greater ease of construction.

[0004] In high-altitude transmission line areas, the constant strong winds, snow, and other extreme weather conditions, along with the tension of the power lines, subject the transmission line tower foundations to alternating compressive / uplift loads and horizontal loads, seriously threatening the safety and stability of the transmission line foundation engineering. Under the action of strong winds and other loads, the windward side of the transmission line tower foundation needs to simultaneously bear a large uplift load and a certain proportion of horizontal load, among which uplift resistance is the main controlling factor for the stability of the tower foundation. Existing transmission line tower foundations are at risk of uplift or overturning under strong winds and other loads, meaning that existing transmission line tower foundations do not have the load-bearing capacity under strong winds and other loads, seriously threatening the safety and stability of the transmission line foundation engineering.

[0005] How to develop transmission line tower foundations with high load-bearing capacity, short construction period, and high degree of mechanization is a key technical issue restricting the rapid development of the power industry in high-altitude mountainous areas. Summary of the Invention

[0006] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0007] To achieve these objectives and other advantages of the present invention, a miniature steel pipe pile tower foundation is provided, comprising a miniature steel pipe disposed in a pile hole, the miniature steel pipe being filled with cement mortar, and a ground bearing platform being connected to the top of the miniature steel pipe;

[0008] The bottom of the micro steel pipe is symmetrically provided with multiple overflow ports, and each of the multiple overflow ports is hinged with a pressing mechanism for forming an enlarged head at the pile end.

[0009] The prestressing application mechanism has its bottom connected to a plurality of the extrusion mechanisms, and its top is fixedly connected to the ground support.

[0010] Preferably, the extrusion mechanism includes a valve, the top of which is hinged to the micro steel pipe via a rotating shaft, and the valve is located inside the overflow port. A triangular inner wedge is integrally formed and protrudes from the inner side of the valve, and the triangular inner wedge is connected to the prestressing application mechanism. An outer wedge for wedging into the soil is also integrally formed and protrudes from the outer side of the valve.

[0011] Preferably, the prestressing application mechanism includes:

[0012] Prestressed steel bars are threaded through the miniature steel pipes, and the top of the prestressed steel bars passes through the ground foundation.

[0013] A pushing component is disposed at the bottom of the prestressed steel bar, and the pushing component abuts against the plurality of the extrusion mechanisms respectively;

[0014] An anchoring assembly is disposed on top of the prestressed steel reinforcement and abuts against the ground foundation.

[0015] Preferably, the push component includes:

[0016] An anchor plug in the shape of a cone is inserted through the prestressed steel bar, and the outer side of the anchor plug abuts against the plurality of the extrusion mechanisms respectively;

[0017] An anchor plate is fixedly connected to the bottom end of the prestressed steel bar, and the anchor plate abuts against the inner bottom end of the anchor plug.

[0018] Preferably, the anchoring assembly includes a bearing plate that passes through the prestressed steel bars, with the bottom end of the bearing plate abutting against the ground platform and the top end of the bearing plate connected to the prestressed steel bars via an anchor.

[0019] Preferably, the bottom end of the micro steel pipe is provided with multiple symmetrically integrally formed protrusions.

[0020] Preferably, the outer wall of the micro steel pipe is also fixedly connected to two grouting pipes, with one end of the two grouting pipes located at the middle of the bottom end of the micro steel pipe, and the other end of the two grouting pipes penetrating the ground support.

[0021] Preferably, the top end of the micro steel pipe is integrally formed with a flange for connecting the extended steel pipe, and multiple ribs are symmetrically connected between the flange and the outer wall of the micro steel pipe.

[0022] A construction method for a miniature steel pipe pile tower foundation includes the following steps:

[0023] S1. Use small machinery to drill pile holes at the designed location and insert miniature steel pipes into the pile holes;

[0024] S2. Fill the interior of the micro steel pipe with cement mortar;

[0025] S3. Lift the upper end of the prestressed steel bar, and the anchor plate drives the anchor plug to move upward to squeeze the triangular inner wedge, thereby causing the flap to squeeze the soil in the pile hole. The outer wedge on the flap wedged into the soil to increase the friction. The cement mortar in the micro steel pipe entered the squeezed soil to form the pile end enlarged head.

[0026] S4. Construct a ground support around the top of the micro steel pipe and leave holes for the prestressed steel bars to pass through.

[0027] S5. The prestressed steel bars are connected to the bearing plate through anchorages, thereby applying prestress to the prestressed steel bars. The prestress is then applied to the ground bearing platform through the bearing plate.

[0028] S6. After grouting, cement grout is squeezed into the soil layer at the pile end by two grouting pipes fixed to the outer wall of the micro steel pipe. Some of the cement grout seeps into the cracks to form grout veins. After grouting is completed, the grouting port is sealed.

[0029] Preferably, the water-cement ratio of the cement slurry is 0.5 to 0.7;

[0030] The grouting volume of the cement slurry is obtained by the formula:

[0031] G c =α s nd+α p d

[0032] Among them: G c For grouting volume, α s α is the empirical coefficient for the amount of grouting on the pile side. p is the empirical coefficient for the amount of grouting at the pile tip, n is the number of grouting sections on the pile side, and d is the pile diameter;

[0033] The grouting control pressure of the cement slurry is derived from the formula:

[0034]

[0035] Where: P c To control the grouting pressure, P cd The pressure is the control pressure for grouting at the pile tip, and h is the height difference between the pipeline at the pressure sensor and the grouting device on the pile side. d λ is the height difference between the pipeline at the pressure sensor and the grouting device at the pile end, G is the self-weight of the pile, and λ is the height difference between the pipeline at the pressure sensor and the grouting device at the pile end. i q is the pull-out coefficient. ik Let l be the standard value of the side friction resistance of the i-th soil pile. i Let A be the thickness of soil layer i. p This represents the cross-sectional area of ​​the pile end.

[0036] The present invention has at least the following beneficial effects:

[0037] Firstly, this invention utilizes a tower foundation with micro-steel pipe piles as the main structure, enabling mechanized construction, reducing safety risks and labor intensity, and improving construction efficiency. This avoids the need for manual excavation of foundations in transmission line projects, making it suitable for the construction of transmission line tower foundations in high-altitude mountainous areas and showing promising prospects.

[0038] Secondly, this invention combines micro-steel pipe piles, prestressing, and post-grouting technologies. The micro-steel pipe piles and prestressed steel bars improve horizontal bearing capacity, the anchor plug compression forming an enlarged head improves tensile bearing capacity, and post-grouting at the pile end improves compressive bearing capacity. Therefore, this novel micro-steel pipe pile tower foundation possesses excellent comprehensive bearing capacity.

[0039] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the present invention.

[0041] Figure 2 This is a schematic diagram of the miniature steel pipe connection of the present invention.

[0042] Figure 3 This is a schematic diagram of the extrusion mechanism of the present invention.

[0043] Figure 4 This is a schematic diagram of the connection of the push component of the present invention.

[0044] Figure 5 This is a schematic diagram of the anchoring component connection of the present invention.

[0045] Figure 6 This is a schematic diagram of the flange connection according to the present invention. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0047] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0048] It should be noted that in the description of this invention, the orientations or positional relationships indicated by terms are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Furthermore, in this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Moreover, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0051] Figure 1 An embodiment of the present invention is shown, which includes a micro steel pipe 2 disposed in a pile hole 1, the micro steel pipe 2 being filled with cement mortar 3, and a ground bearing platform 4 being connected to the top of the micro steel pipe 2;

[0052] The bottom of the micro steel pipe 2 is symmetrically provided with multiple overflow ports 21, and each of the multiple overflow ports 21 is hinged with a pressing mechanism 5 for forming the pile end enlargement head 7.

[0053] The prestressing application mechanism 6 is connected at its bottom to a plurality of the extrusion mechanisms 5, and the top of the prestressing application mechanism 6 is fixedly connected to the ground support platform 4.

[0054] The diameter of the miniature steel pipe 2 is no more than 400 mm, and the wall thickness is 4 to 25 mm.

[0055] The surface of the micro steel pipe 2 is coated with an anti-corrosion material to prevent the micro steel pipe 2 from rusting.

[0056] Working Principle: During the construction of the tower foundation, after drilling the pile hole 1 at the designed location, a miniature steel pipe 2 is placed inside the pile hole 1, and cement mortar 3 is filled into the inside of the miniature steel pipe 2. The cement mortar 3 flows from the bottom of the miniature steel pipe 2 into the gap between the miniature steel pipe 2 and the pile hole 1, forming external cement mortar 3. Then, the prestressing application mechanism 6 drives the extrusion mechanism 5, causing the extrusion mechanism 5 to continuously extrude the soil outward, forcing some of the external cement mortar 3 into the surrounding soil. The cement mortar 3 inside the miniature steel pipe 2 enters the extruded soil, forming the pile end enlarged head 7. Subsequently, a ground bearing platform 4 is constructed around the top of the miniature steel pipe 2, and the top of the prestressing application mechanism 6 is connected to the ground bearing platform 4 to apply prestress. In this technical solution, the horizontal bearing capacity is improved by the prestressing application mechanism 6, and the extrusion of the extrusion mechanism 5 causes the cement mortar 3 to form the enlarged head 7 integrally, improving the pull-out bearing capacity. This achieves an improvement in the comprehensive performance of the miniature steel pipe 2 pile tower foundation, with the beneficial effects of improving construction efficiency, reducing labor intensity, and reducing operational risks.

[0057] As described above, the extrusion mechanism 5 includes a flap 51. The top of the flap 51 is hinged to the micro steel pipe 2 via a rotating shaft, and the flap 51 is located inside the overflow port 21. A triangular inner wedge 52 is integrally formed and protrudes from the inner side of the flap 51, and the triangular inner wedge 52 is connected to the prestressing application mechanism 6. An outer wedge 53 for wedging into the soil is also integrally formed and protrudes from the outer side of the flap 51.

[0058] Working principle: When the prestressing application mechanism 6 is lifted, the prestressing application mechanism 6 abuts against the triangular inner wedge 52. As the prestressing application mechanism 6 moves upward, the triangular inner wedge 52 pushes the valve 51 outward to squeeze it, and the outer wedge 53 wedges into the soil. As the valve 51 continues to squeeze the soil outward, the cement mortar 3 in the micro steel pipe 2 enters the squeezed soil to form the pile end enlarged head 7.

[0059] As described above, the prestressing application mechanism 6 includes:

[0060] The prestressed steel bar 61 is threaded through the micro steel pipe 2, and the top of the prestressed steel bar 61 passes through the ground support 4.

[0061] A pushing component 62 is disposed at the bottom of the prestressed steel bar 61, and the pushing component 62 abuts against the plurality of extrusion mechanisms 5 respectively;

[0062] An anchoring component 63 is disposed on top of the prestressed steel bar 61 and abuts against the ground bearing platform 4.

[0063] Working principle: After the micro steel pipe 2 is filled with cement mortar 3, the upper end of the prestressed steel bar 61 is lifted, which causes the prestressed steel bar 61 to drive the pushing component 62 to move upward. After the pushing component 62 contacts the triangular inner wedge 52, the pushing valve 51 is squeezed outward, and the outer wedge 53 is wedged into the soil. The cement mortar 3 in the micro steel pipe 2 enters the squeezed soil to form the pile end enlarged head 7. After the ground bearing platform 4 is constructed around the top of the micro steel pipe 2, the prestressed steel bar 61 is connected to the ground bearing platform 4 through the anchoring component 63 to apply prestress.

[0064] As described above, the push component 62 includes:

[0065] An anchor plug 621, which is in the shape of a cone, is inserted through the prestressed steel bar 61, and the outer side of the anchor plug 621 abuts against the plurality of the extrusion mechanisms 5 respectively.

[0066] An anchor plate 622 is fixedly connected to the bottom end of the prestressed steel bar 61, and the anchor plate 622 abuts against the inner bottom end of the anchor plug 621.

[0067] Working principle: After the micro steel pipe 2 is filled with cement mortar 3, the upper end of the prestressed steel bar 61 is lifted, so that the anchor plate 622 abuts against the inner bottom end of the anchor plug 621. The anchor plate 622 drives the anchor plug 621 to move upward. After the cone-shaped anchor plug 621 contacts the triangular inner wedge 52, it pushes the valve 51 outward to squeeze, thereby realizing the pushing of the valve 51.

[0068] As described above, the anchoring component 63 includes a pressure plate 631, which is inserted through the prestressed steel bar 61, and the bottom end of the pressure plate 631 abuts against the ground platform 4, and the top end of the pressure plate 631 is connected to the prestressed steel bar 61 through an anchor 632.

[0069] Working principle: After constructing the ground bearing platform 4 around the top of the micro steel pipe 2, the bearing plate 631 is inserted through the prestressed steel bar 61, and the bearing plate 631 is connected to the prestressed steel bar 61 through the anchor 632, thereby applying prestress to the prestressed steel bar 61, so that the bearing plate 631 applies the prestress to the ground bearing platform 4.

[0070] As described above, the bottom end of the micro-steel pipe 2 is symmetrically and integrally formed with multiple support legs 23. These support legs 23 at the bottom end of the micro-steel pipe 2 prevent a seal from forming at the bottom end after it is placed inside the pile hole 1, thus ensuring that the cement mortar 3 inside the micro-steel pipe 2 can flow from the bottom of the micro-steel pipe 2 into the gap between the micro-steel pipe 2 and the pile hole 1, forming cement mortar 3 outside the pipe.

[0071] As described above, the outer wall of the micro steel pipe 2 is also fixedly connected with two grouting pipes 22, and one end of the two grouting pipes 22 is located at the middle of the bottom end of the micro steel pipe 2, and the other end of the two grouting pipes 22 passes through the ground support 4.

[0072] The grouting pipe 22 is a steel pipe with a diameter of 25-38 mm and a wall thickness of not less than 2.8 mm.

[0073] Working principle: After prestressing is applied to the prestressed steel bar 61, cement grout is injected into the two grouting pipes 22 through the ground grouting equipment. The cement grout squeezes the soil layer at the pile end, and some cement grout seeps into the cracks to form grout veins 8, thereby reducing the void ratio and improving the compressive bearing capacity of the pile end.

[0074] In the above scheme, the top end of the micro steel pipe 2 is integrally formed with a flange 24 for connecting the extended steel pipe, and multiple ribs 25 are symmetrically connected between the flange 24 and the outer wall of the micro steel pipe 2.

[0075] Working principle: When the length of the micro steel pipe 2 cannot meet the construction requirements, the extended steel pipe is connected by the flange 24 integrally formed and protruding at the top of the micro steel pipe 2, thereby extending the length of the micro steel pipe 2 to meet different pile length requirements, and the structural strength of the flange 24 is guaranteed by multiple ribs 25.

[0076] Example:

[0077] A construction method for a miniature steel pipe pile tower foundation includes the following steps:

[0078] S1. At the design location of the micro steel pipe pile tower foundation in the high-altitude route area, a small mechanical drill is used to drill pile holes 1, and micro steel pipes 2 are inserted into pile holes 1.

[0079] S2. Fill the interior of the micro steel pipe 2 with cement mortar 3;

[0080] S3. Lift the upper end of the prestressed steel bar 61. The anchor plate 622 drives the anchor plug 621 to move upward and squeeze the triangular inner wedge 52, thereby causing the valve 51 to squeeze the soil in the pile hole 1. The outer wedge 53 on the valve 51 wedges into the soil to increase friction. The cement mortar 3 in the micro steel pipe 2 enters the squeezed soil to form the pile end enlarged head 7.

[0081] S4. Construct a ground support platform 4 around the top of the micro steel pipe 2, and leave holes for the prestressed steel bars 61 to pass through.

[0082] S5. The prestressed steel bar 61 is connected to the bearing plate 631 through the anchor 632, thereby applying prestress to the prestressed steel bar 61. The prestress is applied to the ground bearing platform 4 through the bearing plate 631.

[0083] S6. After grouting, the cement grout is squeezed into the soil layer at the pile end by two grouting pipes 22 fixed to the outer wall of the micro steel pipe 2. Some of the cement grout seeps into the cracks to form grout veins 8. After grouting is completed, the grouting port is sealed.

[0084] The water-cement ratio of the cement slurry is 0.5 to 0.7;

[0085] The grouting volume of the cement slurry is obtained by the formula:

[0086] G c =α s nd+α p d

[0087] Among them: G c For grouting volume, α s α is the empirical coefficient for the amount of grouting on the pile side. p is the empirical coefficient for the amount of grouting at the pile tip, n is the number of grouting sections on the pile side, and d is the pile diameter;

[0088] Among them, the empirical coefficient α for pile side grouting volume s The empirical coefficient α for pile tip grouting volume p The range of values ​​is shown in Table 1;

[0089]

[0090] Table 1

[0091] The grouting control pressure of the cement slurry is derived from the formula:

[0092]

[0093] Where: P c To control the grouting pressure, P cd The pressure is the control pressure for grouting at the pile tip, and h is the height difference between the pipeline at the pressure sensor and the grouting device on the pile side. d λ is the height difference between the pipeline at the pressure sensor and the grouting device at the pile end, G is the self-weight of the pile, and λ is the height difference between the pipeline at the pressure sensor and the grouting device at the pile end. i q is the pull-out coefficient. ik Let l be the standard value of the side friction resistance of the i-th soil pile. i Let A be the thickness of soil layer i. pThis represents the cross-sectional area of ​​the pile end.

[0094] Wherein, the pull-out coefficient λ i Take the values ​​from Table 2;

[0095] <![CDATA[λ i ]]> 0.7～0.8 0.5～0.7

[0096] Table 2

[0097] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A miniature steel pipe pile tower foundation, comprising miniature steel pipes installed in pile holes, the miniature steel pipes being filled with cement mortar, and a ground bearing platform connected to the top of the miniature steel pipes, characterized in that: The bottom of the micro steel pipe is symmetrically provided with multiple overflow ports, and each of the multiple overflow ports is hinged with a pressing mechanism for forming an enlarged head at the pile end. The prestressing application mechanism has its bottom connected to a plurality of the extrusion mechanisms, and its top is fixedly connected to the ground support platform. The bottom end of the micro steel pipe is symmetrically and integrally formed with multiple support legs. Two grouting pipes are also fixedly connected to the outer wall of the micro steel pipe, with one end of the two grouting pipes located at the middle of the bottom end of the micro steel pipe, and the other end of the two grouting pipes passing through the ground support platform. The prestressing application mechanism includes: Prestressed steel bars are threaded through the miniature steel pipes, and the top of the prestressed steel bars passes through the ground foundation. A pushing component is disposed at the bottom of the prestressed steel bar, and the pushing component abuts against the plurality of the extrusion mechanisms respectively; An anchoring assembly is disposed on top of the prestressed steel reinforcement and abuts against the ground foundation.

2. The miniature steel pipe pile tower foundation according to claim 1, characterized in that, The extrusion mechanism includes a valve, the top of which is hinged to the micro steel pipe via a rotating shaft, and the valve is located inside the overflow port. A triangular inner wedge is integrally formed and protrudes from the inner side of the valve, and the triangular inner wedge is connected to the prestressing application mechanism. An outer wedge for wedging into the soil is also integrally formed and protrudes from the outer side of the valve.

3. The miniature steel pipe pile tower foundation according to claim 1, characterized in that, The push component includes: An anchor plug in the shape of a cone is inserted through the prestressed steel bar, and the outer side of the anchor plug abuts against the plurality of the extrusion mechanisms respectively; An anchor plate is fixedly connected to the bottom end of the prestressed steel bar, and the anchor plate abuts against the inner bottom end of the anchor plug.

4. The miniature steel pipe pile tower foundation according to claim 1, characterized in that, The anchoring assembly includes a bearing plate that passes through the prestressed steel bars, with the bottom end of the bearing plate abutting against the ground platform and the top end of the bearing plate connected to the prestressed steel bars via an anchor.

5. The miniature steel pipe pile tower foundation according to claim 1, characterized in that, The top of the micro steel pipe is integrally formed with a flange for connecting the extended steel pipe, and multiple ribs are symmetrically connected between the flange and the outer wall of the micro steel pipe.

6. A construction method for a miniature steel pipe pile tower foundation according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Use small machinery to drill pile holes at the designed location and insert miniature steel pipes into the pile holes; S2. Fill the inside of the micro steel pipe with cement mortar; S3. Lift the upper end of the prestressed steel bar, and the anchor plate drives the anchor plug to move upward to squeeze the triangular inner wedge, thereby causing the flap to squeeze the soil in the pile hole. The outer wedge on the flap wedged into the soil to increase the friction. The cement mortar in the micro steel pipe entered the squeezed soil to form the pile end enlarged head. S4. Construct a ground support around the top of the micro steel pipe and leave holes for the prestressed steel bars to pass through. S5. The prestressed steel bars are connected to the bearing plate through anchorage, thereby applying prestress to the prestressed steel bars. The prestress is then applied to the ground bearing platform through the bearing plate. S6. After grouting, cement grout is squeezed into the soil layer at the pile end by two grouting pipes fixed to the outer wall of the micro steel pipe. Some of the cement grout seeps into the cracks to form grout veins. After grouting is completed, the grouting port is sealed.

7. The construction method for miniature steel pipe pile tower foundation according to claim 6, characterized in that, The water-cement ratio of the cement slurry is 0.5~0.7; The grouting volume of the cement slurry is obtained by the formula: Among them: G c For grouting volume, α s α is the empirical coefficient for the amount of grouting on the pile side. p is the empirical coefficient for the amount of grouting at the pile tip, n is the number of grouting sections on the pile side, and d is the pile diameter; The grouting control pressure of the cement slurry is derived from the formula: Where: P c To control the grouting pressure, P cd The pressure is the control pressure for grouting at the pile tip, and h is the height difference between the pipeline at the pressure sensor and the grouting device on the pile side. d G represents the height difference between the pipeline at the pressure sensor and the grouting device at the pile end, and G is the self-weight of the pile. The pull-out coefficient, For the first Standard value of side friction resistance of layered soil piles for The thickness of the soil layer, A p This represents the cross-sectional area at the pile end.

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