A full-assembled threaded steel pipe UHPC composite pile foundation and a construction method thereof

Abstract

This invention discloses a fully prefabricated UHPC (Ultra-High-Pressure Polymer) threaded steel pipe composite pile foundation and its construction method, relating to the field of pile foundation technology. The device includes a support platform and multiple pile foundation units. The support platform has multiple mounting grooves, and the upper end of each pile foundation unit extends into one of these grooves. Each pile foundation unit includes a threaded steel pipe pilot pile and several threaded steel pipe extension piles, which are connected sequentially from top to bottom. The upper end of the threaded steel pipe pilot pile can connect to the lower end of the lowest threaded steel pipe extension pile. The pilot pile contains a pilot precast filling pile, and each threaded steel pipe extension pile contains an extension precast filling pile. Both the pilot precast filling pile and the extension precast filling piles are made of UHPC. This invention effectively solves the problems of complex construction procedures, long construction periods, insufficient bearing capacity, and environmental pollution caused by on-site grouting in traditional grouting threaded steel pipe pile construction.

Description

Technical Field

[0001] This invention relates to the field of pile foundation technology, and in particular to a fully assembled threaded steel pipe UHPC composite pile foundation and its construction method. Background Technology

[0002] Reinforced concrete bored piles and precast PHC piles are currently the most widely used pile foundation structures in large-scale engineering projects. Among them, the construction technology of reinforced concrete bored piles is relatively mature and can withstand large vertical and horizontal loads. However, when using the process of drilling holes on-site and pouring concrete underwater, it often causes serious environmental pollution, extremely long construction periods, high labor intensity, and difficulty in inspecting the actual pile quality. This is especially true in urban environments where environmental protection requirements are higher and living areas are becoming increasingly dense, making construction difficult. In addition, the difficulty in transporting and constructing large drilling equipment in mountainous areas or scenic spots with complex terrain also limits the application of bored piles.

[0003] Traditional high-strength prestressed concrete (PHC) pipe piles are widely used in a large number of construction projects due to their high structural strength, easy quality inspection, economy, and ease of rapid on-site construction. However, the disadvantages of PHC pipe piles are: (1) due to limitations in construction equipment, the pile size cannot be too large, resulting in weak bending and shear resistance; (2) due to the heavy self-weight of concrete, the length of a single pile section should not be too large after considering transportation factors, and the multi-joint structure will reduce the overall pile bearing capacity; (3) the pile driving process is prone to pile misalignment (misalignment of pile joints), which leads to pile body bending cracks or even pile breakage; (5) the pile joints are welded on-site, which has high requirements for the on-site environment and construction team, and the joints are prone to rust, affecting the durability of the pile foundation.

[0004] Besides the two types of pile foundation structures mentioned above, precast threaded steel pipe pile structures are also widely used in many small structures due to their simple construction. However, when applied to concrete buildings or bridge structures with greater load-bearing requirements, they often have insufficient load-bearing capacity.

[0005] Therefore, there is an urgent need in this field for a fully assembled threaded steel pipe UHPC composite pile foundation and its construction method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a fully assembled UHPC (Ultra-High-Pressure Polymer) threaded steel pipe composite pile foundation and its construction method, which solves the technical problems existing in the prior art. By utilizing the excellent compressive strength and toughness of UHPC, the size of the components is greatly reduced while ensuring the strength and stability of the components, thus reducing the requirements for mechanical transportation and hoisting capabilities during assembly and construction. It has the characteristics of being green and environmentally friendly, simple and quick to construct, reliable in quality, significantly improved in bearing capacity, and wide in applicability. It can effectively solve the problems of complex construction procedures, long construction period, insufficient bearing capacity, and environmental pollution caused by on-site grouting of traditional grouted threaded steel pipe piles.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention discloses a fully assembled threaded steel pipe UHPC composite pile foundation, including a support cap and multiple pile foundation units. The support cap is provided with multiple mounting grooves, and the upper end of each pile foundation unit extends into the mounting groove.

[0009] The pile foundation unit includes a threaded steel pipe pilot pile and several threaded steel pipe extension piles, which are connected sequentially from top to bottom. The upper end of the threaded steel pipe pilot pile can be connected to the lower end of the threaded steel pipe extension pile located at the bottom.

[0010] The pilot pile of the threaded steel pipe is provided with a pilot precast filling pile inside, and each extension pile of the threaded steel pipe is provided with an extension precast filling pile inside. The pilot precast filling pile and the extension precast filling pile are both made of UHPC.

[0011] Preferably, the lower end of the threaded steel pipe extension pile is provided with a connecting sleeve, the lower end of the connecting sleeve is provided with a plurality of sleeve slots, the upper end of the threaded steel pipe pilot pile is provided with a plurality of connecting bolts, the connecting bolts can be inserted into the sleeve slots, and the connecting bolts can be threadedly connected to a connecting nut after passing through the sleeve slots.

[0012] Preferably, the lower end of the connecting sleeve located at the lowest end is provided with three sleeve slots, the three sleeve slots are evenly distributed in the circumferential direction of the connecting sleeve, and the included angle between the centers of two adjacent sleeve slots is 120°.

[0013] The upper end of the threaded steel pipe pilot pile is provided with two layers of bolt groups, each of which includes three connecting bolts. The included angle between the centers of two adjacent connecting bolts in each bolt group is 120°.

[0014] Preferably, the inner and outer walls of the threaded steel pipe pilot pile and the threaded steel pipe extension pile are both provided with a galvanized layer.

[0015] Preferably, the connection between the threaded steel pipe pilot pile and the lowermost threaded steel pipe extension pile is staggered with the connection between the pilot precast filling pile and the lowermost extension precast filling pile.

[0016] Preferably, the mounting groove is a circular groove, the depth of the mounting groove is greater than the diameter of the threaded steel pipe extension pile, the inner diameter of the mounting groove is the same as the outer diameter of the threaded steel pipe extension pile, and the distance between two adjacent mounting grooves is greater than or equal to the diameter of the threaded steel pipe extension pile.

[0017] Preferably, the support platform is a cuboid structure with dimensions of 2.50m × 2.50m × 1.00m, and has 16 mounting grooves.

[0018] Preferably, there are two threaded steel pipe extension piles, the length of the two threaded steel pipe extension piles is 3m, and the length of the threaded steel pipe pilot pile is 4m.

[0019] This invention also discloses a construction method for a fully prefabricated threaded steel pipe UHPC composite pile foundation, which includes the following steps based on the above-mentioned fully prefabricated threaded steel pipe UHPC composite pile foundation:

[0020] S1. Precast support pile cap, pilot precast filling pile and extended precast filling pile: Based on the inner diameter of the threaded steel pipe pilot pile and the threaded steel pipe extended pile, make molds with the same inner diameter, and pour the corresponding pilot precast filling pile and extended precast filling pile according to the design parameters; make the template of the support pile cap according to the design dimensions of the support pile cap, and set the number of installation grooves at the bottom corresponding to the number of pile foundation units, and pour and cure the corresponding support pile cap according to the design parameters;

[0021] S2. Piling of threaded steel pipe pilot piles: The threaded steel pipe pilot piles and prefabricated pilot precast filling piles are transported to the site. At the pre-positioned center of the pile foundation, the threaded steel pipe pilot piles are driven into the soil using a pile driving machine. The pilot precast filling piles are then vertically hoisted to directly above the threaded steel pipe pilot piles. Finally, the pilot precast filling piles are driven into the threaded steel pipe pilot piles until the top of the pilot precast filling piles reaches the predetermined position at the top of the threaded steel pipe pilot piles.

[0022] S3. Splicing of threaded steel pipe extension piles: The threaded steel pipe extension pile is suspended above the threaded steel pipe pilot pile, and then lowered so that the lower end of the first threaded steel pipe extension pile is inserted along the upper end of the pilot precast filling pile. Then, the connecting sleeve at the lower end of the first threaded steel pipe extension pile is connected to the upper end of the threaded steel pipe pilot pile and fixed with connecting bolts, so that the threaded steel pipe extension pile and the threaded steel pipe pilot pile are combined into a whole.

[0023] S4. Threaded steel pipe extension pile construction: Connect the top of the first threaded steel pipe extension pile to a pile driving machine. Use the pile driving machine to drive the first threaded steel pipe extension pile into the soil. After the first threaded steel pipe extension pile is driven into the soil, hang the first precast infill pile vertically directly above the first threaded steel pipe extension pile. Insert the bottom of the first precast infill pile into the first threaded steel pipe extension pile and lower it until the bottom of the first precast infill pile reaches the top of the pilot precast infill pile.

[0024] S5. If the bottom of the threaded steel pipe pilot pile does not reach the designed pile bottom elevation after the first threaded steel pipe extension pile is screwed into the soil, then repeat steps S3 and S4 to continue adding threaded steel pipe extension piles until the bottom of the threaded steel pipe pilot pile reaches the designed pile bottom elevation and the top of the uppermost threaded steel pipe extension pile is level with the top of its corresponding extension precast filling pile.

[0025] S6. Repeat steps S1-S5 to screw all the necessary individual piles supporting the pile cap into the soil to form a pile group.

[0026] S7. Vertically hoist the prefabricated support platform above the pile group, align the pre-reserved installation groove below the support platform with the corresponding pile foundation unit, and hoist the support platform downwards until the pile foundation unit is completely inserted into the pre-reserved installation groove of the support platform.

[0027] Preferably, flatbed trucks are used for transportation in steps S2-S7, and crawler cranes are used for hoisting.

[0028] The present invention achieves the following technical effects compared to the prior art:

[0029] 1. All components in this invention (including threaded steel pipe pilot piles, threaded steel pipe extension piles, support caps, pilot precast filling piles, extension precast filling piles, and connecting bolts) can be precast components, which can be precast in large quantities in the factory and then assembled on site. This can effectively solve the problems of slow progress, large construction area, and serious environmental pollution in traditional cast-in-place pile foundation construction methods.

[0030] 2. In this invention, both the pilot precast filling piles and the extension piles are filled with UHPC material. The ultra-high strength, high toughness, and ultra-high tensile strength of UHPC (ultra-high performance concrete) can be utilized to overcome the problems of insufficient bearing capacity and easy cracking of ordinary concrete pile foundations in bridge engineering applications. On the other hand, under the same stress conditions, the self-weight of the pile foundation can be reduced, creating favorable conditions for the prefabrication, transportation, and assembly of composite piles.

[0031] 3. Due to the high density, high strength, high toughness, and super tensile strength and excellent wear resistance of UHPC, the corrosion resistance, durability and explosion resistance of this invention are significantly improved compared with ordinary concrete. It can adapt well to various harsh environments and greatly expand the application scope of assembled threaded steel pipe piles in bridge engineering.

[0032] 4. The support platform in this invention is prefabricated, which can effectively solve the series of quality problems caused to the components by the large amount of hydration heat generated during the pouring of large volume concrete.

[0033] 5. This invention adopts a fully prefabricated design, which has the advantages of fast construction speed, simple process, easy control of project quality, and small construction site occupation;

[0034] 6. The present invention does not require high mechanical transportation and hoisting capabilities during construction, saving manpower and facilitating mechanization. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a diagram illustrating the first arrangement of the fully assembled threaded steel pipe UHPC composite pile foundation in Example 1.

[0037] Figure 2 This is a diagram illustrating the second arrangement of the fully assembled threaded steel pipe UHPC composite pile foundation in Example 1;

[0038] Figure 3 This is a schematic diagram of the threaded steel pipe extension pile in the fully assembled threaded steel pipe UHPC composite pile foundation of Example 1;

[0039] Figure 4 This is a schematic diagram of the threaded steel pipe pilot pile in the fully assembled threaded steel pipe UHPC composite pile foundation of Example 1;

[0040] Figure 5 This is a top view of the threaded steel pipe pilot pile in the fully assembled threaded steel pipe UHPC composite pile foundation of Example 1;

[0041] Figure 6 This is a schematic diagram of the pilot precast filling pile in the fully assembled threaded steel pipe UHPC composite pile foundation of Example 1;

[0042] Figure 7This is a schematic diagram of the extended precast infill pile in the fully assembled threaded steel pipe UHPC composite pile foundation of Example 1;

[0043] Figure 8 This is a flowchart illustrating the construction method of the fully assembled threaded steel pipe UHPC composite pile foundation in Example 2.

[0044] In the diagram: 1-Threaded steel pipe pilot pile; 2-Pilot precast filling pile; 3-Threaded steel pipe extension pile; 4-Extended precast filling pile; 5-Supporting pile cap; 6-Installation groove; 7-Connecting sleeve; 8-Connecting nut; 9-Sleeve slot; 10-Connecting bolt. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The purpose of this invention is to provide a fully assembled UHPC (Ultra-High-Pressure Polymer) threaded steel pipe composite pile foundation and its construction method, which solves the technical problems existing in the prior art. By utilizing the excellent compressive strength and toughness of UHPC, the size of the components is greatly reduced while ensuring the strength and stability of the components, thus reducing the requirements for mechanical transportation and hoisting capabilities during assembly and construction. It has the characteristics of being green and environmentally friendly, simple and quick to construct, reliable in quality, significantly improved in bearing capacity, and wide in applicability. It can effectively solve the problems of complex construction procedures, long construction period, insufficient bearing capacity, and environmental pollution caused by on-site grouting of traditional grouted threaded steel pipe piles.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1

[0049] like Figures 1-7 As shown, this embodiment provides a fully assembled threaded steel pipe UHPC composite pile foundation, including a support cap 5 and multiple pile foundation units. The multiple pile foundation units form a pile group. The support cap 5 is provided with multiple mounting grooves 6. The number of mounting grooves 6 corresponds to the number of pile foundation units that need to be fixed. The upper end of the pile foundation unit extends into and is fixed in a corresponding mounting groove 6.

[0050] The pile foundation unit includes a threaded steel pipe pilot pile 1 and several threaded steel pipe extension piles 3. The outer side of both the threaded steel pipe pilot pile 1 and the several threaded steel pipe extension piles 3 are provided with threaded structures, while the lower end of the threaded steel pipe pilot pile 1 is a tapered structure. The several threaded steel pipe extension piles 3 are connected sequentially from top to bottom, and the upper end of the threaded steel pipe pilot pile 1 can be connected to the lower end of the threaded steel pipe extension pile 3 located at the bottom.

[0051] The pilot pile 1 of the threaded steel pipe has a pilot precast filling pile inside. Each extension pile 3 of the threaded steel pipe has a corresponding extension precast filling pile 4 inside. The pilot precast filling pile and the extension precast filling pile 4 are both made of UHPC. They are precast in the factory using ultra-high performance concrete. Utilizing the high strength, high toughness and ultra-high tensile properties of ultra-high performance concrete (UHPC), the tensile strength of the UHPC filling pile body material is 15MPa~40MPa and the compressive strength is 150MPa~200MPa. Its bearing capacity is more than 5 times that of traditional pipe piles. The bearing capacity of the UHPC filling pile body can generally be controlled by the strength of the pile body concrete, so that the vertical compressive bearing capacity of the pipe pile can be fully utilized. The pile adopts a segmented installation method, which facilitates transportation, simplifies installation, and greatly improves construction efficiency.

[0052] In practical applications, the fully prefabricated threaded steel pipe UHPC composite pile foundation has two different pile foundation layout forms for different terrains:

[0053] like Figure 1 As shown, the first arrangement is: the individual pile foundation is perpendicular to the lower surface of the supporting pile cap 5, which is suitable for relatively flat plains with level ground.

[0054] like Figure 2 As shown, arrangement form two: the pile foundation unit and the lower surface of the supporting pile cap 5 have a certain angle, which is suitable for mountainous areas with more complex terrain, slopes, etc.

[0055] In this embodiment, as Figure 3 As shown, the lower end of the threaded steel pipe extension pile 3 is provided with a connecting sleeve 7. The lower end of the connecting sleeve 7 is provided with a number of sleeve slots 9 evenly distributed in the circumferential direction. The upper end of the threaded steel pipe pilot pile 1 is provided with a number of connecting bolts 10. The connecting bolts 10 can be inserted into the corresponding sleeve slots 9. After the connecting bolts 10 pass through the sleeve slots 9, they can be threadedly connected to the connecting nuts 8.

[0056] When the lower end of the threaded steel pipe extension pile 3 located at the bottom is connected to the upper end of the threaded steel pipe pilot pile 1, the connecting bolts 10 at the upper end of the threaded steel pipe extension pile 3 are inserted into the corresponding sleeve slots 9, and then the connecting nuts 8 are tightened to fix it.

[0057] It should be noted that when two or more threaded steel pipe extension piles 3 are installed, the connection method of two adjacent threaded steel pipe extension piles 3 is the same as described above. That is, the connecting sleeve 7 at the lower end of the upper threaded steel pipe extension pile 3 is connected and fixed to the connecting bolt 10 at the upper end of the lower threaded steel pipe extension pile 3.

[0058] That is, when multiple threaded steel pipe extension piles 3 are provided, each threaded steel pipe extension pile 3 has a connecting sleeve 7 at its lower end and multiple connecting bolts 10 at its upper end. It should be noted that the uppermost threaded steel pipe extension pile 3 does not need to be equipped with connecting bolts 10 because it needs to be connected to the support platform 5.

[0059] In this embodiment, the lower end of the connecting sleeve 7 is provided with three sleeve grooves 9, which are evenly distributed in the circumferential direction of the connecting sleeve 7, and the included angle between the centers of two adjacent sleeve grooves 9 is 120°. Furthermore, the length of the connecting sleeve 7 is 0.60m, the width of the sleeve grooves 9 is 30mm, and the length of the sleeve grooves 9 is 0.42m. When multiple threaded steel pipe extension piles 3 are provided, the remaining dimensions are the same.

[0060] Corresponding to the connecting sleeve 7, the upper end of the threaded steel pipe pilot pile 1 is provided with two layers of bolt groups. Of course, those skilled in the art can also set it to one, three, four or more layers according to actual needs. Each bolt group includes three connecting bolts 10. The connecting bolts 10 are existing high-strength bolts with a diameter of 40mm. The inner diameter of the matching connecting nut 8 is 40mm and the outer diameter is 80mm. The included angle between the centers of two adjacent connecting bolts 10 in each bolt group is 120°. The distance between the two corresponding connecting bolts 10 is 0.2m, and the distance from the upper connecting bolt 10 to the top of the bolted steel pipe pilot pile is 0.2m. Furthermore, the upper ends of the remaining threaded steel pipe extension piles 3 (except for the threaded steel pipe extension piles 3 connected to the support pile 5) are also provided with connecting bolts 10, and the size and distribution are the same as the connecting bolts 10 on the threaded steel pipe pilot pile 1.

[0061] In this embodiment, both the inner and outer walls of the threaded steel pipe pilot pile 1 and the threaded steel pipe extension pile 3 are provided with a galvanized layer for rust prevention, which effectively increases the corrosion resistance of the threaded steel pipe pilot pile 1 and the threaded steel pipe extension pile 3 and extends their service life.

[0062] In this embodiment, the connection between the threaded steel pipe pilot pile 1 and the lowermost threaded steel pipe extension pile 3 is staggered with the connection between the pilot precast filling pile 2 and the lowermost extension precast filling pile. This design not only improves the bearing capacity of the composite pile, but also facilitates the combined installation of the threaded steel pipe pilot pile 1 and the threaded steel pipe extension pile 3 during construction.

[0063] Structurally, the upper end of the pilot precast filling pile 2 is higher than the upper end of the threaded steel pipe pilot pile 1. Similarly, the upper end of the bottommost (first) extended precast filling pile 4 is higher than the upper end of the bottommost (first) threaded steel pipe extended pile 3. The upper end of the second extended precast filling pile 4 is also higher than the upper end of the second threaded steel pipe extended pile 3, and so on. This continues until the upper end of the highest (last) extended precast filling pile 4 is flush with the upper end of the highest (last) threaded steel pipe extended pile 3.

[0064] Furthermore, the length of the threaded steel pipe extension pile 3 located in the middle position (i.e., excluding the threaded steel pipe extension pile 3 at the top) must be the same as the length of its corresponding extended precast filling pile 4, and the length of the extended precast filling pile 4 above the corresponding threaded steel pipe extension pile 3 must be greater than the diameter of the threaded steel pipe extension pile 3. The length of the threaded steel pipe extension pile 3 at the top must be greater than the length of its corresponding extended precast filling pile 4, thus achieving a flush top between the uppermost threaded steel pipe extension pile 3 and the extended precast filling pile 4.

[0065] In this embodiment, the mounting groove 6 is a circular groove, the size of which must match the uppermost threaded steel pipe extension pile 3. The depth of the mounting groove 6 is greater than the diameter of the threaded steel pipe extension pile 3, specifically, the depth of the mounting groove 6 must be no less than 1.5 times the diameter of the threaded steel pipe extension pile 3. The inner diameter of the mounting groove 6 is the same as the outer diameter of the threaded steel pipe extension pile 3, and the distance between two adjacent mounting grooves 6 is greater than or equal to the diameter of the threaded steel pipe extension pile 3.

[0066] In this embodiment, the support platform 5 is a cuboid structure with dimensions of 2.50m × 2.50m × 1.00m. The support platform 5 has 16 mounting grooves 6 with an inner diameter of 0.30m and a depth of 0.40m. The center-to-center distance between any two mounting grooves 6 in both the horizontal and vertical directions is 0.60m, and the vertical distance from the center of the outermost mounting groove 6 in both the horizontal and vertical directions to the edge of the support platform 5 is 0.50m. Of course, the shape details and dimensions can be determined according to the shape of the bridge pier or column to be supported above the support platform 5, and the number of mounting grooves 6 is determined by the bearing capacity and the number of individual pile foundations to be supported below.

[0067] In this embodiment, two threaded steel pipe extension piles 3 are provided, each with a length of 3m. The length of the threaded steel pipe pilot pile 1 is 4m, and the total length of the pile foundation is 10.00m. The outer diameter of both the threaded steel pipe pilot pile 1 and the threaded steel pipe extension pile 3 is 0.30m, the inner diameter is 0.26m, and the wall thickness is 20mm. Starting 0.80m from the bottom, the threaded steel pipe pilot pile 1 tapers downwards in a variable cross-section manner to the bottom, with a complementary angle of 11.00°.

[0068] Of course, in other embodiments, there may be three or more threaded steel pipe extension piles 3, which are ultimately determined by the design elevation of the pile bottom; the lengths of the threaded steel pipe extension piles 3 and the threaded steel pipe pilot piles 1 are determined according to the capabilities of the construction machinery.

[0069] The inner diameter of the pilot precast filling pile 2 and the two extended precast filling piles 4 is 0.26m, and the length of the pilot precast filling pile 2 is 4.29m. When the pilot precast filling pile 2 is fully lowered into the threaded steel pipe pilot pile 1 during construction, the top of the pilot precast filling pile 2 is 0.40m higher than the top of the threaded steel pipe pilot pile 1. The length of the extended precast filling pile 4 corresponding to the first threaded steel pipe extension pile 3 is 3.00m, and the length of the extended precast filling pile 4 corresponding to the second threaded steel pipe extension pile 3 (i.e., connected to the support pile 5) is 2.60m. When the extended precast filling pile 4 corresponding to the second threaded steel pipe extension pile 3 is lowered into the second threaded steel pipe extension pile 3, the top surface of the second extended precast filling pile 4 is flush with the top surface of the second threaded steel pipe extension pile 3.

[0070] In this embodiment, the steel cages used for the pilot precast filling pile and the extended precast filling pile 4 are all ordinary ribbed steel bars. The ordinary ribbed steel bars are HRB400, and the steel bar diameter is 12mm, 25mm or 28mm.

[0071] Example 2

[0072] like Figure 8 As shown, this embodiment provides a construction method for a fully prefabricated threaded steel pipe UHPC composite pile foundation, based on the fully prefabricated threaded steel pipe UHPC composite pile foundation of Embodiment 1, including the following steps:

[0073] S1, Precast Support Foundation 5, Pilot Precast Filling Piles and Extended Precast Filling Piles 4: Based on the inner diameter of the threaded steel pipe pilot pile 1 and the threaded steel pipe extended pile 3, molds with the same inner diameter are made, and the corresponding pilot precast filling piles and extended precast filling piles 4 are poured according to the design parameters; the template of the support foundation 5 is made according to the design dimensions of the support foundation 5, and the number of installation grooves 6 corresponding to the number of pile foundation units is set at the bottom, and the corresponding support foundation 5 is poured and cured according to the design parameters;

[0074] S2. Piling of the threaded steel pipe pilot pile 1: The threaded steel pipe pilot pile 1 and the prefabricated pilot precast filling pile 2 are transported to the site. At the center position of the pre-positioned pile foundation, the threaded steel pipe pilot pile 1 is driven into the soil layer by a pile driving machine. The pilot precast filling pile 2 is vertically hoisted to directly above the threaded steel pipe pilot pile 1. Then the pilot precast filling pile 2 is sent into the threaded steel pipe pilot pile 1 until the top of the pilot precast filling pile 2 reaches the predetermined position at the top of the threaded steel pipe pilot pile 1.

[0075] S3. Splicing of threaded steel pipe extension pile 3: The threaded steel pipe extension pile 3 is suspended above the threaded steel pipe pilot pile 1, and then lowered so that the lower end of the first threaded steel pipe extension pile 3 is inserted along the upper end of the pilot precast filling pile 2. Then the connecting sleeve 7 at the lower end of the first threaded steel pipe extension pile 3 is connected to the upper end of the threaded steel pipe pilot pile 1 and fixed with connecting bolts 10, so that the threaded steel pipe extension pile 3 and the threaded steel pipe pilot pile 1 are combined into a whole.

[0076] S4. Pile Construction of Threaded Steel Pipe Extension Pile 3: Connect the top of the first threaded steel pipe extension pile 3 to a pile driving machine. Drive the first threaded steel pipe extension pile 3 into the soil layer using the pile driving machine. After the first threaded steel pipe extension pile 3 is driven into the soil, hang the first extended precast filling pile 4 vertically directly above the first threaded steel pipe extension pile 3. Insert the bottom of the first extended precast filling pile 4 into the first threaded steel pipe extension pile 3 and lower it until the bottom of the first extended precast filling pile 4 reaches the top of the pilot precast filling pile 2.

[0077] S5. If the bottom of the first threaded steel pipe extension pile 3 has not reached the designed pile bottom elevation after being screwed into the soil, then repeat the construction steps S3 and S4 and continue to add threaded steel pipe extension piles 3 until the bottom of the threaded steel pipe pilot pile 1 reaches the designed pile bottom elevation and the top of the uppermost threaded steel pipe extension pile 3 is level with the top of its corresponding extended precast filling pile 4.

[0078] S6. Repeat steps S1-S5 to screw all the necessary individual piles supporting the pile cap 5 into the pile soil to form a pile group.

[0079] S7. Vertically hoist the prefabricated support platform 5 above the pile group, align the pre-reserved installation groove 6 below the support platform 5 with the corresponding pile foundation unit, and hoist the support platform 5 downwards until the pile foundation unit is completely inserted into the pre-reserved installation groove 6 of the support platform 5.

[0080] In this embodiment, in steps S2-S7, flatbed trucks with a load capacity of 1000 tons or more are used for transportation, and crawler cranes with a load capacity of 300 tons or more are used for hoisting.

[0081] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A fully prefabricated UHPC composite pile foundation with threaded steel pipe, characterized in that: It includes a support platform and multiple pile foundation units. The support platform is provided with multiple mounting grooves, and the upper end of each pile foundation unit extends into the mounting groove. The pile foundation unit includes a threaded steel pipe pilot pile and several threaded steel pipe extension piles, which are connected sequentially from top to bottom. The upper end of the threaded steel pipe pilot pile can be connected to the lower end of the threaded steel pipe extension pile located at the bottom. The pilot pile of the threaded steel pipe is provided with a pilot precast filling pile inside, and each extension pile of the threaded steel pipe is provided with an extension precast filling pile inside. The pilot precast filling pile and the extension precast filling pile are both made of UHPC.

2. The fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 1, characterized in that: The lower end of the threaded steel pipe extension pile is provided with a connecting sleeve, and the lower end of the connecting sleeve is provided with several sleeve slots. The upper end of the threaded steel pipe pilot pile is provided with several connecting bolts. The connecting bolts can extend into the sleeve slots, and the connecting bolts are connected by connecting nuts after passing through the sleeve slots.

3. The fully assembled threaded steel pipe UHPC composite pile foundation according to claim 2, characterized in that: The lower end of the connecting sleeve located at the lowest end is provided with three sleeve slots. The three sleeve slots are evenly distributed in the circumferential direction of the connecting sleeve, and the included angle between the centers of two adjacent sleeve slots is 120°. The upper end of the threaded steel pipe pilot pile is provided with two layers of bolt groups, each of which includes three connecting bolts. The included angle between the centers of two adjacent connecting bolts in each bolt group is 120°.

4. The fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 1, characterized in that: The inner and outer walls of both the threaded steel pipe pilot pile and the threaded steel pipe extension pile are provided with a galvanized layer.

5. The fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 1, characterized in that: The connection between the threaded steel pipe pilot pile and the lowest threaded steel pipe extension pile is staggered with the connection between the pilot precast filling pile and the lowest extension precast filling pile.

6. The fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 1, characterized in that: The mounting groove is a circular groove, the depth of the mounting groove is greater than the outer diameter of the threaded steel pipe extension pile, the inner diameter of the mounting groove is the same as the outer diameter of the threaded steel pipe extension pile, and the distance between two adjacent mounting grooves is greater than or equal to the diameter of the threaded steel pipe extension pile.

7. The fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 1, characterized in that: The support platform is a cuboid structure with dimensions of 2.50m × 2.50m × 1.00m, and has 16 mounting grooves.

8. The fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 1, characterized in that: The threaded steel pipe extension pile is provided in two sections, each with a length of 3m, and the threaded steel pipe pilot pile has a length of 4m.

9. A construction method for a fully prefabricated UHPC composite pile foundation with threaded steel pipe, characterized in that, The fully assembled threaded steel pipe UHPC composite pile foundation according to claim 1 includes the following steps: S1. Precast support pile cap, pilot precast filling pile and extended precast filling pile: Based on the inner diameter of the threaded steel pipe pilot pile and the threaded steel pipe extended pile, make molds with the same inner diameter, and pour the corresponding pilot precast filling pile and extended precast filling pile according to the design parameters; make the template of the support pile cap according to the design dimensions of the support pile cap, and set the number of installation grooves at the bottom corresponding to the number of pile foundation units, and pour and cure the corresponding support pile cap according to the design parameters; S2. Piling of threaded steel pipe pilot piles: The threaded steel pipe pilot piles and prefabricated pilot precast filling piles are transported to the site. At the pre-positioned center of the pile foundation, the threaded steel pipe pilot piles are driven into the soil using a pile driving machine. The pilot precast filling piles are then vertically hoisted to directly above the threaded steel pipe pilot piles. Finally, the pilot precast filling piles are driven into the threaded steel pipe pilot piles until the top of the pilot precast filling piles reaches the predetermined position at the top of the threaded steel pipe pilot piles. S3. Splicing of threaded steel pipe extension piles: The threaded steel pipe extension pile is suspended above the threaded steel pipe pilot pile, and then lowered so that the lower end of the first threaded steel pipe extension pile is inserted along the upper end of the pilot precast filling pile. Then, the connecting sleeve at the lower end of the first threaded steel pipe extension pile is connected to the upper end of the threaded steel pipe pilot pile and fixed with connecting bolts, so that the threaded steel pipe extension pile and the threaded steel pipe pilot pile are combined into a whole. S4. Threaded steel pipe extension pile construction: Connect the top of the first threaded steel pipe extension pile to a pile driving machine. Use the pile driving machine to drive the first threaded steel pipe extension pile into the soil. After the first threaded steel pipe extension pile is driven into the soil, hang the first precast infill pile vertically directly above the first threaded steel pipe extension pile. Insert the bottom of the first precast infill pile into the first threaded steel pipe extension pile and lower it until the bottom of the first precast infill pile reaches the top of the pilot precast infill pile. S5. If the bottom of the threaded steel pipe pilot pile does not reach the designed pile bottom elevation after the first threaded steel pipe extension pile is screwed into the soil, then repeat steps S3 and S4 to continue adding threaded steel pipe extension piles until the bottom of the threaded steel pipe pilot pile reaches the designed pile bottom elevation and the top of the uppermost threaded steel pipe extension pile is level with the top of its corresponding extension precast filling pile. S6. Repeat steps S1-S5 to screw all the necessary individual piles supporting the pile cap into the soil to form a pile group. S7. Vertically hoist the prefabricated support platform above the pile group, align the pre-reserved installation groove below the support platform with the corresponding pile foundation unit, and hoist the support platform downwards until the pile foundation unit is completely inserted into the pre-reserved installation groove of the support platform.

10. The construction method of the fully prefabricated threaded steel pipe UHPC composite pile foundation according to claim 9, characterized in that: In steps S2-S7, flatbed trucks are used for transportation, and crawler cranes are used for hoisting.

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