A new type of assembled steel pipe pile support and water stop method

Abstract

The present application relates to the field of foundation pit support, and discloses a novel assembled steel pipe row pile support and water stopping method, the novel assembled steel pipe row pile support comprising a middle steel pipe pile, a corner steel pipe pile and a connecting steel pipe, an open round steel pipe is arranged on the pile body of the middle steel pipe pile and the corner steel pipe pile, the open round steel pipe has a circumferential notch, and a 'T' shaped split toe is distributed on the inner side of the notch, the adjacent pile bodies are connected through the nesting engagement of the connecting steel pipe inserted into the open round steel pipe, and a continuous row pile structure is formed, the present application forms a mechanical sealing water stopping system, adapts to different stratum water stopping requirements, the core components are prefabricated in the factory and connected in an assembled manner, the construction is simplified and the cycle is shortened, the steel pipe pile can be recycled and reused, the cost is reduced, and the present application is green and environmentally friendly, the support structure has high rigidity and clear force transmission, is suitable for deep foundation pits and protects surrounding buildings and pipes, the special corner steel pipe pile realizes seamless connection at the corner, the connecting limb plate can be adjusted as required, and the geological adaptability is improved.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support technology, and more specifically, to a novel prefabricated steel pipe pile support and water-stopping method. Background Technology

[0002] Deep foundation pit construction refers to a complete set of support, excavation and monitoring technologies developed in underground space development to ensure the safety of deep foundation pit excavation and underground structure construction. Its core includes retaining structures mainly based on diaphragm walls, reinforced concrete or steel pipe internal support systems, advanced construction methods such as reverse construction / semi-reverse construction, as well as auxiliary measures such as soil reinforcement and dewatering. It addresses challenges such as the protection of adjacent buildings and underground pipelines and the control of stratum deformation in complex environments, and achieves safe and green construction of deep foundation pit projects.

[0003] In the construction of deep foundation pit projects, traditional concrete piles are expensive, have poor water-stopping effect, and are not suitable for reuse, which seriously affects the construction cycle and project cost of foundation pit projects. In addition, the installation and dismantling of traditional steel support systems are mostly done on-site in a piecemeal manner, with low standardization of components, complex connection node treatment, low construction efficiency, and strong dependence on the technical level of construction personnel. Summary of the Invention

[0004] This invention provides a novel prefabricated steel pipe pile support and water-stopping method, which solves the technical problems of high cost of concrete piles, poor water-stopping, low standardization of steel support system, low on-site assembly efficiency and complex joint treatment in related technologies.

[0005] This invention provides a novel prefabricated steel pipe pile support system, comprising central steel pipe piles, corner steel pipe piles, and connecting steel pipes; The central steel pipe pile and the corner steel pipe pile are equipped with open circular steel pipes. The open circular steel pipes have circumferential notches, and "T"-shaped toes are distributed inside the notches. Adjacent piles are nested and interlocked by inserting connecting steel pipes into open circular steel pipes to form a continuous pile structure. The "T"-shaped toe seals the pores between piles under the pressure of the stratum, and works in conjunction with the water-stopping material to form a mechanical sealing water-stopping system.

[0006] As a further optimization of the present invention, the central steel pipe pile is a hot-rolled round steel pipe, with an open round steel pipe welded to one side and a steel pipe welded to the other side through a connecting limb plate. The outer diameter of the connecting steel pipe is smaller than the inner diameter of the open circular steel pipe. Adjacent middle steel pipe piles are interlocked by inserting the connecting steel pipe into the open circular steel pipe. The number of connecting plates is determined according to the soil conditions. A single connecting plate is used when the soil is hard, and two connecting plates are used when the soil is soft.

[0007] As a further optimization of the present invention, the corner steel pipe pile is a round steel pipe, and an open round steel pipe II and an open round steel pipe III are welded to it in two mutually perpendicular directions respectively. Both open circular steel pipes 2 and 3 have notches around their circumferences, with "T"-shaped toes distributed inside the notches. These toes are used to connect the middle steel pipe piles in the long and short directions of the foundation pit, achieving structural transition and closure at the corners.

[0008] As a further optimization of the present invention, the "T"-shaped toes distributed inside the circumferential notch of the open circular steel pipe deform under the squeezing action of the stratum mudstone and soil when the connecting steel pipe is inserted, thereby sealing the gap between the "T"-shaped toes and the connecting steel pipe. In sandy, water-rich strata, the ends of the "T"-shaped toe are pre-coated with hemp fibers mixed with butter, sealant, or quick-setting mortar to form an enhanced waterproof sealing layer.

[0009] As a further optimization of the present invention, it also includes steel brackets, steel walers, horizontal steel supports, and supporting steel columns; The steel bracket is composed of two pentagonal steel plates welded together, with an internal horizontal support plate and vertical stiffening ribs, welded to the side of the central steel pipe pile; The steel waler is a composite beam structure formed by welding the upper and lower flanges of double H-beams. Vertical stiffening ribs one and two are welded on both sides of the composite beam at intervals of 0.5 to 1.0 meters, forming a closed force transmission structure around the perimeter of the foundation pit. The steel walers are placed on steel brackets and are bolted to the horizontal steel supports.

[0010] As a further optimization of the present invention, the horizontal steel support is prefabricated in sections from rolled H-beams, with bolt holes reserved in the end flanges and webs of each section, and rapid splicing is achieved by adding steel plates and bolt groups through openings; The supporting steel columns are integral rolled box-shaped steel columns, combined rectangular steel pipe columns, or lattice columns. The bottom is embedded in the jet grouting pile or cast-in-place pile foundation, and the top is welded with an open end plate, which is connected to the lower flange of the horizontal steel support by bolts.

[0011] A novel prefabricated steel pipe pile support and water-stopping method, employing the aforementioned novel prefabricated steel pipe pile support, includes the following steps: Measurement and positioning: Level the site, measure the boundary line of the foundation pit and the control coordinate points of the support piles, and mark them on the ground; Piles are driven: Water-stopping material is applied to the "T"-shaped toe ends of the open circular steel pipes. Vibratory hammers or static pressure equipment are used to drive the middle steel pipe piles one by one along the long side of the foundation pit, so that the connecting steel pipes are inserted into the open circular steel pipes to form a closed structure that interlocks with each other. Corner construction: Using the connecting steel pipe of the last central steel pipe pile at the corner of the foundation pit as a positioning fulcrum, the corner steel pipe pile is lifted and driven, so that the open round steel pipes on both sides of the corner steel pipe pile are inserted into the connecting steel pipe. Waler installation: Excavate the first layer of foundation pit to the elevation of the bottom of the steel corbel, weld the steel corbel to the side of the central steel pipe pile, and install the steel waler; Construction of the support system: Construction of the steel column foundation, installation of horizontal steel supports by lifting in sections, and bolt connection with the steel walers and support steel columns; Layered excavation: Excavate in layers with a thickness not exceeding 3.0m, first supporting and then excavating, gradually constructing to the design elevation of the foundation.

[0012] As a further optimization of the present invention, during pile driving: a theodolite or plumb bob is used to assist in measuring and maintaining the verticality of the pile body; After the driving is completed, the inside of the steel pipe pile is filled with sand excavated from the foundation pit, and small-diameter end-sealing steel pipes can be used for tamping to enhance the rigidity of the pile body. During the installation of the walers and the layered excavation, steel brackets were welded multiple times at different heights of the central steel pipe piles according to the excavation depth of the foundation pit, and multiple horizontal steel supports were installed in layers.

[0013] As a further optimization of the present invention, during the construction of the support system, the horizontal steel support is divided into several standard segments according to the span and hoisting capacity, and the segments are quickly spliced ​​together by adding steel plates with holes and bolt groups. The spacing of the supporting steel columns is determined based on the span and deflection of the horizontal steel supports.

[0014] As a further optimization of the present invention, a recycling step is also included: After the foundation slab is completed, the horizontal steel supports are removed layer by layer from bottom to top; After the foundation construction is completed, the steel walers will be removed. After the foundation pit is backfilled and compacted, the central and corner steel pipe piles are removed one by one using pile extraction machinery. After each pile extraction, the pores are backfilled and compacted using grouting or fluidized solidified soil to prevent ground cracking and deformation, thus enabling the reuse of steel pipe piles.

[0015] The beneficial effects of this invention are as follows: 1. This invention utilizes the deformation sealing of the inner "T"-shaped toe of the open circular steel pipe under the pressure of the stratum to form a mechanical sealing water-stopping system in combination with the synergistic effect of water-stopping materials. In sandy and water-rich strata, an enhanced sealing layer can also be formed by pre-coating water-stopping materials to seal the gaps between piles and meet the water-stopping needs of different strata in the foundation pit.

[0016] 2. In this invention, the core components of the support system, such as the central steel pipe piles, corner steel pipe piles, and horizontal steel supports, are all factory-prefabricated standardized products. Adjacent piles are connected by nesting and interlocking, and the horizontal steel supports are quickly assembled using bolt groups. The steel walers, steel corbels, and horizontal steel supports are also connected by bolts, replacing the traditional method of on-site assembly of steel supports. This simplifies node processing, reduces reliance on the technical level of construction personnel, and enables rapid assembly and construction of foundation pit support, shortening the construction cycle.

[0017] 3. After the foundation pit construction of this invention is completed, the core components such as the central steel pipe piles and corner steel pipe piles can be removed by pile extraction machinery and reused after simple processing. Compared with the traditional concrete piles, which are not recyclable and have high costs, this invention reduces the cost of engineering materials. At the same time, after the piles are extracted, the pores are backfilled by grouting or fluidized solidified soil to reduce ground cracking and deformation and reduce the generation of construction waste, which is in line with the concept of green construction.

[0018] 4. The steel pipe piles in the middle of this invention can be filled with sand and compacted to enhance the rigidity of the pile body. The steel walers adopt a double H-shaped steel composite beam structure and are equipped with vertical stiffening ribs to form a closed force transmission structure. The horizontal steel supports can be set in layers according to the depth of the foundation pit. The bottom of the support steel columns is embedded with jet grouting piles / cast-in-place piles. The overall support system has a clear force transmission path, strong bearing capacity, reduces ground deformation, and is suitable for deep foundation pit projects with different excavation depths. At the same time, it can protect the safety of adjacent buildings and underground pipelines.

[0019] 5. This invention designs a special corner steel pipe pile, which sets open circular steel pipes with "T"-shaped toes in two mutually perpendicular directions. This can achieve seamless connection between the steel pipe piles in the middle of the long and short sides of the foundation pit, complete the structural transition and closure at the corner, and solve the problems of difficult connection and poor sealing of traditional support structures at the corner of the foundation pit. Moreover, the number of connecting plates can be flexibly adjusted according to the soil conditions, further improving the adaptability of the support system to different geological conditions.

[0020] 6. This invention adopts a construction method of layered excavation (layer thickness not exceeding 3.0m) and support before excavation. According to the excavation depth of the foundation pit, steel brackets can be welded at different heights of steel pipe piles and horizontal steel supports can be installed in layers. The construction can be carried out step by step to the design elevation of the foundation. This reduces soil deformation and support structure displacement during the foundation pit excavation process, reduces safety hazards such as foundation pit collapse, and improves the safety of deep foundation pit excavation and underground structure construction. Attached Figure Description

[0021] Figure 1 This is a structural schematic diagram of a novel prefabricated steel pipe pile support proposed in this invention; Figure 2 This is a schematic diagram of the central steel pipe pile structure proposed in this invention; Figure 3 This is a schematic diagram of the corner steel pipe pile proposed in this invention; Figure 4 This is a schematic diagram of the cross-sectional structure of the steel waler proposed in this invention; Figure 5 This is a schematic diagram of the connection structure between the steel bracket and the steel waler proposed in this invention.

[0022] In the picture: 1. Central steel pipe pile; 2. Open round steel pipe I; 3. Connecting limb plate; 4. Connecting steel pipe; 5. Corner steel pipe pile; 6. Open round steel pipe II; 7. Open round steel pipe III; 8. Steel waler; 9. Corner brace; 10. Horizontal steel support; 11. Supporting steel column; 12. Steel bracket; 13. H-beam I; 14. Vertical stiffening rib I; 15. H-beam II; 16. Vertical stiffening rib II. Detailed Implementation

[0023] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0024] Example 1 Reference Figures 1 to 5 As shown, a new type of prefabricated steel pipe pile support includes a central steel pipe pile 1, an open round steel pipe 1 2, a connecting limb plate 3, a connecting steel pipe 4, a corner steel pipe pile 5, an open round steel pipe 2 6, an open round steel pipe 3 7, a steel waler 8, a corner brace 9, a horizontal steel support 10, a supporting steel column 11, a steel corbel 12, an H-beam 13, a vertical stiffening rib 14, an H-beam 2 15, and a vertical stiffening rib 2 16. Corner brace 9 is installed at the corner of steel waler 8.

[0025] The central steel pipe pile 1 is a hot-rolled round steel pipe of a certain diameter and wall thickness. An open round steel pipe 2 is welded to one side, and a connecting leg plate 3 is welded to the other side. Steel brackets 12 are welded to the side of the central steel pipe pile 1 on a plane perpendicular to the line connecting the open round steel pipe 2 and the connecting leg plate 3. After the central steel pipe piles 1 are interconnected to form a pile bank, they are connected to open round steel pipes 6 at both corners. The diameter of the open round steel pipe 2 is larger than that of the connecting steel pipe 4, and it has a notch on its circumference, the width of which is slightly larger than the thickness of the connecting limb plate 3. "T"-shaped toes are distributed on the inner side of the circumferential notch. The connecting steel pipe 4 can be freely inserted into the open round steel pipe 2. The connecting plate 3 is a steel plate of a certain thickness and width, and the end is welded to the connecting steel pipe 4; The diameter of the connecting steel pipe 4 is smaller than the inner diameter of the open round steel pipe 2, which ensures that the open round steel pipe 2 can be freely inserted and pulled out. The diameter of the open circular steel pipe 26 is larger than that of the connecting steel pipe 4, and there is a notch on its circumference, the width of which is slightly larger than the thickness of the connecting limb plate 3. A corner steel pipe pile 5 is welded to one side of the open circular steel pipe 26; The corner steel pipe pile 5 is a round steel pipe with a certain diameter and a certain wall thickness. An open round steel pipe 2 6 is welded on one side, and an open round steel pipe 3 7 is welded on the other side. The open circular steel pipe 37 has a notch on its circumference, the diameter of which is larger than that of the connecting steel pipe 4, and the width of the notch is slightly greater than the thickness of the connecting limb plate 3. "T"-shaped toes are distributed on the inner side of the circumferential notch. The connecting steel pipe 4 can be freely inserted into the open circular steel pipe 37. The steel bracket 12 is a bracket support composed of two pentagonal steel plates welded together. The steel plates have a certain wall thickness. Two horizontal support plates are welded between the two pentagonal steel plates at the top and bottom, and a vertical stiffening rib is welded between the horizontal support plates. A steel waler 8 is placed on top. The steel waler 8 is a composite beam formed by welding the upper and lower flanges of rolled H-beams 13 and 15 respectively. Vertical stiffeners 14 and 16 are welded to both sides of the composite beam, forming a closed structure around the perimeter of the foundation pit. One side of the steel waler 8 is connected to the horizontal steel support 10 by welding or bolting. The horizontal steel support 10 uses rolled H-beams and is divided into multiple segments according to the structural span capacity, enabling industrial prefabrication. Each segment has pre-drilled bolt holes on its end flanges and webs, and they are quickly connected to each other using perforated additional steel plates to form a complete horizontal support that participates in load-bearing. Depending on the magnitude of the bending deformation generated by the horizontal steel support 10, supporting steel columns 11 can be appropriately added at the bottom of the beam within the span. The supporting steel column 11 can be a whole rolled box steel column, a combined rectangular steel pipe column or a lattice column. The bottom is embedded in the jet grouting pile or the cast-in-place pile, and the top is welded with an open end plate and connected to the lower flange of the horizontal steel support 10 by bolts. The vertical stiffener 14 is a steel plate of a certain thickness. The three sides of the steel plate are welded to the upper flange, lower flange and web of the rolled H-beam 13 to form a short stiffener. The vertical stiffener 216 is a steel plate of a certain thickness. The three sides of the steel plate are welded to the upper flange, lower flange and web of the rolled H-beam 215 to form a short stiffener. A novel prefabricated steel pipe pile support and water-stopping method, employing the aforementioned novel prefabricated steel pipe pile support, includes the following steps: First, level the site, measure the boundary line of the foundation pit and the control coordinate points of the support piles, and mark them on the ground with lime. Apply a mixture of hemp fiber and grease, sealant, or quick-setting mortar to the "T"-shaped toe ends of the open circular steel pipes 2 and 6. Using a vibratory hammer or static pressure equipment, drive the piles one by one from the middle of the long side of the foundation pit towards the other. Simultaneously, drive or press the first central steel pipe pile 1 into the pit along the measured control points, using a theodolite or plumb line to maintain the verticality of the pile. Continue by lifting the second central steel pipe pile 1 using the same method, and insert the open circular steel pipe 2 into the connecting steel pipe 4 to form an interlocking closed structure. Repeat this process to complete the driving of the central steel pipe piles 1 on one side of the foundation pit. To ensure the rigidity of the steel pipe piles, fill the inside of the steel pipes with leveled excavated sand, and if necessary, use small-diameter end-sealing steel pipes for compaction.

[0026] Once all the central steel pipe piles 1 on one side of the foundation pit are completed along the predetermined direction, the connecting steel pipe 4 of the last central steel pipe pile 1 near the corner of the foundation pit is used as a positioning fulcrum to lift the corner steel pipe pile 5. The open circular steel pipes 2 6 or 3 7 on both sides of the corner steel pipe pile 5 are then inserted into and wrapped around the connecting steel pipe 4. A vibratory hammer or static pressure equipment is then used for driving, thus completing the construction of the corner steel pipe pile 5. Following the predetermined pile driving sequence, the first central steel pipe pile 1 in the vertical direction of the short side is driven, and the connecting steel pipe 4 is inserted into the open circular steel pipe 3 7. This process is repeated to complete the construction of the steel pipe piles in the short side direction.

[0027] After the support piles on both the long and short sides of the foundation pit have been constructed, the decision to add a pile cap beam can be made based on the excavation depth. If the foundation pit is deep and the soil quality is poor, a steel cap beam or concrete cap beam should be added to the top of the row of piles formed by the central steel pipe piles 1 and the corner steel pipe piles 5. Then, the first layer of foundation pit soil is excavated, with the initial excavation depth reaching the bottom elevation of the steel corbel 12 on the pile side. The steel corbel 12 is welded to the side of the central steel pipe pile 1 according to the design position, and the steel waler 8 is installed. The central support steel column 11 is constructed using spiral drilling, SMW method piles, or bored cast-in-place piles, ensuring that the support steel column 11 is inserted into the pile hole filled with cement grout. After the concrete in the pile hole has initially set, the horizontal steel supports 10 are installed in sections according to the lifting capacity of a single piece of equipment. The installation of the horizontal steel supports 10 proceeds from one end to the other, and high-strength bolts with pre-drilled holes are used to connect them to the steel walers 8 and the supporting steel columns 11. The number of horizontal steel supports 10 installed should be determined based on the length of the long side of the foundation pit. After the horizontal steel supports 10 are installed, the foundation pit is excavated again, with an excavation depth not exceeding 3.0m. Steel brackets 12 need to be welded again to the lower side of the central steel pipe pile 1, and then the horizontal steel supports 10 are installed in sections. Following a 3.0m layer excavation thickness, the supports are installed first, followed by excavation, gradually progressing to the design elevation of the foundation.

[0028] After the foundation slab is completed, as the building or structure grows, the horizontal steel supports 10 should be removed gradually from bottom to top, and should be removed in layers. After the foundation construction is completed, the steel walers 8 should be removed. After the foundation pit is backfilled and compacted, the central steel pipe piles 1 and the corner steel pipe piles 5 should be removed one by one using pile extraction machinery. After each pile extraction, the gaps should be filled and compacted with grout or fluidized solidified soil to prevent ground cracking and deformation caused by pile extraction. The central steel pipe piles 1 and the corner steel pipe piles 5 can be reused.

[0029] Example 2 Based on Example 1, an open circular steel pipe 2 is welded to one side of the central steel pipe pile 1, and a connecting steel pipe 4 with connecting limb plate 3 is welded to the other side. By hammering or static pressure on the top of the steel pipe pile, the connecting steel pipe 4 is inserted into the open circular steel pipe 2, which can realize the rapid connection between the central steel pipe piles on the long and short sides of the deep foundation pit. The open round steel pipe 26 has "T"-shaped toes distributed on the inner side of the notch. When the connecting steel pipe 4 is inserted into the open round steel pipe 26, the gap between the "T"-shaped toes and the connecting steel pipe 4 can be quickly sealed under the squeezing action of the silty soil and rock in the stratum. If it is in a sandy, water-rich stratum, it is necessary to seal the ends of the "T"-shaped toes with hemp fiber mixed with grease, sealant, or quick-setting mortar in advance to stop the water. The corner steel pipe pile 5 has two open circular steel pipes 6 and 7 welded in two mutually perpendicular directions, and the connecting steel pipe 4 at one end of the middle steel pipe pile 1 near the corner is inserted into it, which can achieve a perfect transition from the long side to the short side support of the foundation pit. Example 3 Based on the above embodiments, a steel bracket 12 is designed on the side near the top of the middle steel pipe pile 1. The steel bracket 12 is welded to the middle steel pipe pile 1. Two pentagonal steel plates are symmetrically arranged along the pile axis. An "I"-shaped stiffening rib is welded between the two steel plates, which can effectively prevent structural buckling deformation. The steel walers 8 are continuously arranged around the perimeter of the foundation pit as a force transmission structure. They are formed by welding rolled H-beam 13 and H-beam 25 together. Vertical stiffening ribs 14 and 26 are welded on both sides along the longitudinal axis at intervals of 0.5 to 1.0 meters to increase the structural rigidity. Example 4 Based on the above embodiments, the connecting plate 3 is a steel plate of a certain thickness. One end is welded to the side of the central steel pipe pile 1, and the other end is welded to the side of the connecting steel pipe 4. The number of connecting plates 3 should be determined according to the soil conditions. If the soil is hard, a single connecting plate 3 should be used; if the soil is soft, two connecting plates 3 should be used for better support. The horizontal steel support 10 should be divided into several standard segments according to the span and the hoisting capacity of the primary equipment. The flanges and webs between the segments are quickly connected by bolt groups, and the ends are connected by bolts at the upper and lower flanges of the steel waler 8. The supporting steel columns 11 are standardized processed components, using whole rolled box-section steel columns, combined rectangular steel pipe columns, or lattice columns. All of these components can be prefabricated in the factory. The distribution spacing should be determined according to the span and deflection deformation of the horizontal steel supports 10, and a sufficient number of supporting steel columns 11 should be set. The upper and lower ends of the supporting steel columns 11 are bolted to the horizontal steel supports 10 using end plates.

[0030] The embodiments of the present invention have been described above, but the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the embodiments described above, all of which are within the protection scope of the embodiments described above.

Claims

1. A novel prefabricated steel pipe pile support system, characterized in that, It includes central steel pipe piles (1), corner steel pipe piles (5) and connecting steel pipes (4); The central steel pipe pile (1) and the corner steel pipe pile (5) are provided with open circular steel pipes. The open circular steel pipes have circumferential notches and "T"-shaped toes are distributed inside the notches. Adjacent piles are nested and interlocked by inserting connecting steel pipes (4) into open circular steel pipes to form a continuous pile structure; The "T"-shaped toe seals the pores between piles under the pressure of the stratum, and works in conjunction with the water-stopping material to form a mechanical sealing water-stopping system.

2. The novel prefabricated steel pipe pile support according to claim 1, characterized in that: The central steel pipe pile (1) is a hot-rolled round steel pipe, with an open round steel pipe (2) welded on one side and a connecting steel pipe (4) welded on the other side through a connecting limb plate (3). The outer diameter of the connecting steel pipe (4) is smaller than the inner diameter of the open round steel pipe (2). The adjacent middle steel pipe piles (1) are connected by inserting the connecting steel pipe (4) into the open round steel pipe (2).

3. The novel prefabricated steel pipe pile support according to claim 1, characterized in that: The corner steel pipe pile (5) is a round steel pipe, and open round steel pipe two (6) and open round steel pipe three (7) are welded in two mutually perpendicular directions respectively. Both the second (6) and the third (7) of the open circular steel pipes have notches around their circumferences. The inner side of the notches is distributed with "T"-shaped toes, which are used to connect the middle steel pipe piles (1) in the direction of the long side and the short side of the foundation pit, so as to realize the structural transition and closure at the corner.

4. The novel prefabricated steel pipe pile support according to claim 1, characterized in that: The "T"-shaped toes distributed inside the circumferential notch of the open circular steel pipe deform under the squeezing action of the stratum mudstone and soil when the connecting steel pipe (4) is inserted, thus sealing the gap between the "T"-shaped toes and the connecting steel pipe (4). In sandy, water-rich strata, the ends of the "T"-shaped toe are pre-coated with hemp fibers mixed with butter, sealant, or quick-setting mortar to form an enhanced waterproof sealing layer.

5. The novel prefabricated steel pipe pile support and water-stopping method according to claim 1, characterized in that: It also includes steel brackets (12), steel walers (8), horizontal steel supports (10) and supporting steel columns (11); The steel bracket (12) is composed of two pentagonal steel plates welded together, with a horizontal support plate and vertical stiffening ribs inside, which are welded to the side of the central steel pipe pile (1); The steel waler (8) is a composite beam structure formed by welding the upper and lower flanges of double H-shaped steel. Vertical stiffening ribs one (14) and two vertical stiffening ribs two (16) are welded at intervals on both sides of the composite beam to form a closed force transmission structure around the perimeter of the foundation pit. The steel waler (8) rests on the steel bracket (12) and is bolted to the horizontal steel support (10).

6. A novel prefabricated steel pipe pile support according to claim 5, characterized in that: The horizontal steel support (10) is prefabricated in sections from rolled H-beams. Bolt holes are reserved in the end flanges and webs of each section. Rapid splicing is achieved by adding steel plates and bolt groups through openings. The supporting steel column (11) is a whole rolled box-shaped steel column, a combined rectangular steel pipe column or a lattice column. The bottom is embedded in the jet grouting pile or cast-in-place pile foundation, and the top is welded with an open end plate. It is connected to the lower flange of the horizontal steel support (10) by bolts.

7. A novel prefabricated steel pipe pile support and water-stopping method, employing the novel prefabricated steel pipe pile support as described in any one of claims 1 to 6, characterized in that: Includes the following steps: Measurement and positioning: Level the site, measure the boundary line of the foundation pit and the control coordinate points of the support piles, and mark them on the ground; Piles are driven: Water-stopping material is applied to the "T"-shaped toe end of the open round steel pipe, and the middle steel pipe piles (1) are driven one by one along the long side of the foundation pit using a vibratory hammer or static pressure equipment, so that the connecting steel pipe (4) is inserted into the open round steel pipe to form a closed structure that interlocks with each other. Corner construction: Using the connecting steel pipe (4) of the last middle steel pipe pile (1) at the corner of the foundation pit as a positioning fulcrum, lift and drive the corner steel pipe pile (5) so that the open round steel pipes on both sides of the corner steel pipe pile (5) are inserted into the connecting steel pipe (4). Waler installation: Excavate the first layer of foundation pit to the bottom elevation of the steel corbel (12), weld the steel corbel (12) to the side of the middle steel pipe pile (1), and install the steel waler (8). Construction of the support system: The foundation of the support steel column (11) is constructed, and the horizontal steel support (10) is installed in sections by lifting and installing it. The support steel column (11) is connected with the steel waler (8) and the support steel column (11) by bolts. Layered excavation: Excavate in layers with a thickness not exceeding 3.0m, first supporting and then excavating, gradually constructing to the design elevation of the foundation.

8. A novel prefabricated steel pipe pile support and water-stopping method according to claim 7, characterized in that: During pile driving: Use a theodolite or plumb bob to assist in measuring and maintaining the verticality of the pile; After the driving is completed, the inside of the steel pipe pile is filled with sand excavated from the foundation pit, and small-diameter end-sealing steel pipes can be used for tamping to enhance the rigidity of the pile body. During the installation of the walers and the layered excavation, steel brackets (12) are welded multiple times at different heights of the central steel pipe pile (1) according to the excavation depth of the foundation pit, and multiple horizontal steel supports (10) are installed in layers.

9. A novel prefabricated steel pipe pile support and water-stopping method according to claim 7, characterized in that: During the construction of the support system, the horizontal steel support (10) is divided into several standard segments according to the span and hoisting capacity. The segments are quickly spliced ​​together by adding steel plates with holes and bolt groups. The spacing of the supporting steel columns (11) is determined based on the span and deflection of the horizontal steel supports (10).

10. A novel prefabricated steel pipe pile support and water-stopping method according to claim 7, characterized in that: It also includes a recycling step: After the foundation slab is completed, the horizontal steel supports are removed layer by layer from bottom to top (10). After the foundation construction is completed, the steel walers are removed (8); After the foundation pit is backfilled and compacted, the middle steel pipe pile (1) and the corner steel pipe pile (5) are removed one by one using pile extraction machinery. After each pile extraction, the pores are backfilled and compacted using grouting or fluidized solidified soil to prevent ground cracking and deformation, thus enabling the reuse of steel pipe piles.

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