Pile cap prefabricated structure and construction method

Abstract

The application discloses a kind of bearing platform prefabricated structure and construction method, it includes multiple independent bearing platform units, and two adjacent bearing platform units can be fixedly connected between, bearing platform unit is the concrete pre-pouring square body with through-hole, the bottom reinforcement cage of bearing platform unit, outer arched reinforcement cage, inner arched reinforcement cage and middle reinforcement cage are all embedded in bearing platform unit by concrete pouring;Each bearing platform unit corresponds to nest one foundation pile, and the concrete poured by two inner arched reinforcement cage and middle reinforcement cage pours the vault flush, so that the upper surface poured by middle reinforcement cage and the bottom surface poured by outer arched reinforcement cage form through-hole between;The bottom surface poured by inner arched reinforcement cage and the upper surface poured by the bottom reinforcement cage form through-hole between.The bearing platform structure of the application can greatly reduce construction time by prefabricated production, and the bearing platform obtained by splicing has the advantages of strong overall compression resistance, good stability and the like, and has popularization prospect and practical value.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology. More specifically, this invention relates to a precast pier cap structure and its construction method. Background Technology

[0002] A pile cap is a reinforced concrete platform set on top of a pile foundation to bear and distribute the load transmitted from the pier. It connects several or even a dozen piles together to form a pile foundation and provides support for the superstructure.

[0003] With the trend towards prefabrication and assembly of land bridges, existing technologies disclose prefabricated pier caps and piers (Announcement No. CN110230319A). These technologies describe prefabricating pier caps into multiple independent pier cap units. The weight of each individual pier cap unit is reduced by utilizing these modular components, facilitating lifting with smaller hoisting equipment. However, each modular pier cap requires high strength and is constructed using cast concrete, resulting in a still significant weight and posing considerable challenges to on-site construction and transportation. Summary of the Invention

[0004] One objective of this invention is to provide a prefabricated foundation structure and construction method. This method utilizes prefabricated foundation units produced in a prefabrication plant in a standardized, large-scale manner, significantly reducing on-site construction time. Furthermore, the internal and external arched structures and through-hole design within the prefabricated foundation units help reduce overall temperature differences, promote structural rigidity, and result in foundations with strong overall compressive strength, good stability, and high load-bearing capacity. Prefabricated foundations also offer advantages such as light weight, facilitating on-site construction and transportation, and saving materials, making them promising for widespread application and practical value.

[0005] To achieve these and other advantages according to the invention, the invention provides a precast foundation structure comprising: a plurality of independent foundation units, wherein adjacent foundation units are fixedly connected, wherein each foundation unit is a precast concrete square body with through holes, and each foundation unit includes:

[0006] A bottom steel reinforcement cage is flatly embedded in the entire lower part of the foundation unit;

[0007] An outer arched steel cage, which is an arc-shaped steel reinforcement connection structure, spans across and covers the bottom steel cage, and the two ends of the outer arched steel cage are connected to the bottom steel cage.

[0008] Two inner arched steel cages, both with arc-shaped steel reinforcement connection structures, are located inside the outer arched steel cage and on the inner sides of the two arch feet of the outer arched steel cage, respectively. The inner arched steel cages overlap and are fixedly connected with the arc surface of the outer arched steel cage. The two inner arched steel cages span across and cover the two ends of the bottom steel cage, and the two ends of the inner arched steel cages are connected to the bottom steel cage.

[0009] The central steel cage is fixed between the arch tops of the two inner arched steel cages;

[0010] A connecting groove is used for nested connection with the foundation pile. The connecting groove is located at the center of the lower part of the foundation unit, between the arch feet of the two inner arched steel cages, and below the middle steel cage. The bottom steel cage surrounds the outer perimeter of the connecting groove. The connecting groove is provided with a grouting inlet and outlet that communicates with the outside. The height of the connecting groove is 1 / 3 to 1 / 2 of the height of the foundation unit.

[0011] The bottom reinforcing cage, outer arched reinforcing cage, inner arched reinforcing cage, and middle reinforcing cage are all embedded in the foundation unit by concrete pouring; each foundation unit corresponds to a nested foundation pile, and the concrete poured for the two inner arched reinforcing cages and the middle reinforcing cage is poured to be flush with their arch tops, so that a through hole is formed between the upper surface of the middle reinforcing cage and the bottom surface of the outer arched reinforcing cage; a through hole is formed between the bottom surface of the inner arched reinforcing cage and the upper surface of the bottom reinforcing cage.

[0012] Preferably, the specific structure that enables two adjacent support units to be fixedly connected is as follows: the connecting surface of the support unit is provided with a groove with a groove opening larger than the bottom of the groove, and a channel is provided from the upper surface of the support unit to the side wall of the groove, through which the groove can be connected to the outside.

[0013] Preferably, the groove is a truncated quadrangular shape, and the connecting surface of the support unit and the bottom of the groove are provided with outwardly extending reinforcing bars.

[0014] Preferably, a reserved ring channel is provided at the lower part of the non-connecting surface of the pier unit. The reserved ring channels of the spliced ​​pier unit can be connected to the outer perimeter in sequence to form an outer ring around the entire pier, which is used to install a ring-shaped steel cage to surround the lower part of the spliced ​​pier and cast into a ring-shaped reinforcing beam.

[0015] This invention also provides a construction method for a precast foundation structure, which utilizes the aforementioned precast foundation structure and includes the following steps:

[0016] 1) Within the environment enclosed by the cofferdam and the bottom sealing concrete layer, the piles are set to extend to the same height. Using hoisting equipment, the foundation unit is hoisted and lowered according to the set dimensions, so that the connecting groove of the foundation unit fits onto the corresponding pile. The height of the pile extending from the bottom sealing concrete layer is 2-3cm smaller than the height of the connecting groove, and the outer diameter of the pile is 3-4cm smaller than the inner diameter of the connecting groove. The foundation unit fits onto the pile and is flush with and presses against the bottom sealing concrete layer. A 40-50cm wet joint is left between two adjacent foundation units. All the through holes of the foundation units spliced ​​into the entire foundation are oriented in the same or parallel directions.

[0017] 2) Erect formwork for the wet joint between two adjacent foundation units, insert reinforcing bars into the ducts, and at the same time, install an annular reinforcing cage around the entire foundation to surround the lower part of the spliced ​​foundation, and erect formwork around the annular reinforcing cage.

[0018] 3) Through the grouting inlet and outlet on the connecting groove, the pile foundation is grouted and tightly connected to the connecting groove. At the same time, concrete is poured into the wet joint and the ring steel cage to form a tightly poured wet joint and a reinforced beam. After curing to the specified strength, the formwork can be removed.

[0019] Preferably, step 2) further includes: horizontally installing multiple telescopic cylinders on the inner side of the cofferdam to push the vertically installed template to move horizontally, thereby controlling the distance between the template and the pier unit, and providing support for the template.

[0020] Preferably, for foundations requiring the splicing of two foundation unit heights, the following is also included:

[0021] A side wall reinforcement cage with a height 50cm lower than the overall height of the pier is placed at the arch feet on both sides of the entire pier. The side wall reinforcement cage is fixedly connected to the ring reinforcement cage of each layer. The template installed on the side wall reinforcement cage is at the same height as the entire pier. The side wall reinforcement cage is located between the side wall of the entire pier and the template, and then it is cast in place.

[0022] The present invention has at least the following beneficial effects:

[0023] First, the foundation unit cast by this invention can be mass-produced and standardized in a prefabrication plant, and can be quickly assembled at the construction site, thus improving efficiency.

[0024] Secondly, the internal and external arched structure and through-hole design of the prefabricated foundation unit of this invention are conducive to reducing the overall temperature difference, promoting structural rigidity, and the overall compressive strength, stability and load-bearing capacity of the spliced ​​foundation are strong. It also has the advantages of light weight, which is conducive to on-site construction and transportation and saves materials. It has the prospects for promotion and practical value.

[0025] 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

[0026] Figure 1 This is a schematic diagram of one implementation of the prefabricated foundation unit of the foundation according to the present invention.

[0027] Figure 2 This is a schematic diagram of one implementation of the prefabricated foundation structure of the present invention, showing the splicing of two foundation units.

[0028] Figure 3 This is a schematic diagram of another implementation of the prefabricated foundation structure of the present invention, showing the splicing of two foundation units.

[0029] Figure 4 This is a schematic diagram of one implementation method of the prefabricated pier structure construction of the present invention;

[0030] Figure 5 This is a schematic diagram illustrating one implementation method of the prefabricated pier structure construction of the present invention.

[0031] Among them, concrete 1; outer arched steel cage 2; inner arched steel cage 3; connecting groove 4; foundation unit 5; foundation pile 6; wet joint 7; reserved ring 8; bottom sealing concrete layer 9; reinforcing beam 10; formwork 11; telescopic cylinder 12; cofferdam 13; through hole 14; middle steel cage 15; bottom steel cage 16; duct 17; groove 18; side wall steel cage 19. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description.

[0033] 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.

[0034] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the structures and components described are commercially available. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship 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 a limitation of this invention.

[0035] like Figure 1-5 As shown, the present invention provides a precast foundation structure, which includes multiple independent foundation units, and adjacent foundation units can be fixedly connected. Each foundation unit is a precast concrete square body with through holes 14. The foundation unit 5 includes:

[0036] A bottom steel cage 16 is flatly embedded in the entire lower part of the foundation unit;

[0037] An outer arched steel cage 2, which is an arc-shaped steel reinforcement connection structure, is embedded in the foundation unit, spans and covers the bottom steel cage 16, and the two ends of the outer arched steel cage 2 are connected to the bottom steel cage 16.

[0038] Two inner arched steel cages 3, both of which are arc-shaped steel reinforcement connection structures, are arranged inside the outer arched steel cage 2 and are respectively located on the inner side of the two arch feet of the outer arched steel cage 2. The inner arched steel cage 3 and the inner tangent arc surface of the outer arched steel cage 2 overlap with the arc surface of the outer arched steel cage 2 and are fixedly connected by steel bars. The two inner arched steel cages 3 are embedded in the foundation unit and respectively span over and cover the two ends of the bottom steel cage 16. The two ends of the inner arched steel cage 3 are connected to the bottom steel cage 16.

[0039] The central steel reinforcement cage 15 is fixed between the arch tops of the two inner arched steel reinforcement cages 3 and embedded in the foundation unit.

[0040] The connecting groove 4 is used for nested connection with the foundation pile 6. The connecting groove 4 is located in the center of the lower part of the foundation unit, between the arch feet of the two inner arched steel cages 3, and below the middle steel cage 15. The bottom steel cage 16 surrounds the outer periphery of the connecting groove 4. The connecting groove 4 is provided with a grouting inlet and outlet that communicates with the outside. The height of the connecting groove 4 is 1 / 3 to 1 / 2 of the height of the foundation unit.

[0041] The bottom reinforcing cage 16, the outer arched reinforcing cage 2, the inner arched reinforcing cage 3, and the middle reinforcing cage 15 are all embedded in the foundation unit by pouring concrete 1; each foundation unit is nested with a foundation pile 6, and the concrete poured by the two inner arched reinforcing cages 3 and the middle reinforcing cage 15 is poured to make their arch tops flush, so that a through hole 14 is formed between the upper surface of the middle reinforcing cage 15 and the bottom surface of the outer arched reinforcing cage 2; a through hole 14 is formed between the bottom surface of the inner arched reinforcing cage 3 and the upper surface of the bottom reinforcing cage 16.

[0042] The precast foundation structure of this invention consists of multiple foundation units. Each foundation unit is fixed to the inner side of an outer arched steel cage 2 by two inner arched steel cages 3. A central steel cage 15 is fixed between the arch tops of the two inner arched steel cages 3. A connecting groove 4 is placed between the inner arched steel cages 3 and below the central steel cage 15, and is surrounded by a bottom steel cage 16. The structure is rigid and integrally cast. Under load, the foundation transmits the external force on the foundation to the pile and the bottom and middle of the foundation unit through the axial force of the inner and outer arched structures. The force at the bottom and middle of the foundation unit is then correspondingly transmitted to the pile and the bottom sealing concrete layer, making the axial force, shear force, and bending moment at the pile top evenly distributed, which is beneficial to improving the load-bearing capacity and stability of the structure. The through hole 14 formed by the precast structure of this invention can also reduce the weight of the precast foundation, which is beneficial to on-site construction and transportation, and saves materials. It has high promotion prospects and practical value.

[0043] Based on the above implementation, the specific structure that enables the fixed connection between two adjacent foundation units is as follows: the connecting surface of the foundation unit is provided with a groove 18 with a groove opening larger than the bottom of the groove, and a channel 17 is provided from the upper surface of the foundation unit to the side wall of the groove 18. The groove 18 can be connected to the outside through the channel 17, which is conducive to the concrete connection between the foundation units, and facilitates the concrete to fill the groove 18, making the splice tight and firm. In addition, steel bars with a diameter more than five times smaller than the inner diameter of the channel 17 can be inserted into the groove 18 and cast into an integral wet joint 7 to further improve the connection effect.

[0044] Based on the above implementation, the groove 18 is a truncated quadrangular shape, and the connecting surface of the support unit and the bottom of the groove 18 are provided with outwardly extending steel bars, which facilitates casting and stable connection. The diameter of the steel bars can be 8mm.

[0045] Based on the above implementation, a reserved ring channel 8 is provided at the lower part of the non-connecting surface of the pier unit. The reserved ring channel 8 of the spliced ​​pier unit can be connected to the outer perimeter in sequence to form an outer ring around the entire pier. This ring is used to install a ring-shaped steel cage, which surrounds the lower part of the spliced ​​pier and is cast to form a ring-shaped reinforcing beam 10, thereby improving the overall stability and giving full play to the advantages of arch bending moment load.

[0046] The reserved ring channel 8 of the foundation unit of the present invention can be set with a depth of 10cm and a width of 10cm, which is conducive to the embedding of the ring-shaped steel cage and integral casting, thereby improving the strength. The foundation unit can be set with a height of 1m or 2m, a length of 2m or 4m, and a width of 2m or 4m, or it can be prefabricated according to special construction requirements.

[0047] Experiment 1

[0048] According to such Figure 3 The above-described pier unit structure of the present invention, taking a pier unit with a height of 2m, a length of 4m, and a width of 4m as an example, has two layers: the outer arched steel cage 2 and the inner arched steel cage. The height between the two layers is 100mm, and the grid size is 200mm×200mm. Steel reinforcement supports with a diameter of 8mm are provided between the two layers at 200mm intervals. The clear span of the through-hole 14 formed by the inner arched steel cage 3 is 0.8m, and the clear rise is 0.08m. The clear span of the through-hole 14 formed by the outer arched steel cage 2 is 2.5m, and the clear rise is 0.25m. The bottom steel cage 16 and the middle steel cage 15 are both double-layered, with a height between the two layers of 400mm and a grid size of 200mm×200mm. The concrete thickness is 0.0mm, the rebar diameter is 8mm; the bottom thickness of the foundation unit is 0.8m; the size of the opening of the truncated pyramidal groove 18 is 150mm×150mm, the bottom is 100mm×100mm, the distance between the opening and the bottom is 150mm, and the inner diameter of the channel 17 is 80mm; the height of the connecting groove 4 is 0.8m, and the inner diameter is 1.5m; the depth of the reserved ring channel 8 is 10cm, and the width is 10cm; the concrete is poured according to the concrete mix proportion in Table 1 and conventionally cured. Samples of the obtained product are taken, and at 28 days of age, 16 test areas are uniformly sampled on the surface of the foundation using the rebound method. The estimated compressive strength of the concrete is above 40 MPa, meeting the C40 strength grade requirement. The maximum temperature difference and temperature stress of the foundation unit are calculated according to the "Standard for Construction of Mass Concrete GB 50496-2018" and are shown in Table 2.

[0049] Experiment 2

[0050] For a standard square-shaped foundation unit structure, taking a foundation unit with a height of 2m, a length of 4m, and a width of 4m as an example, the reinforcing cage is a square reinforcing cage embedded inside the foundation unit. The mesh size is 200mm × 200mm, the reinforcing bar diameter is 8mm, and the reinforcing cage is 1.5m high, 3.5m long, and 3.5m wide. Simultaneously, a 150mm × 150mm groove with a truncated quadrangular groove 18 is fitted on the connection surface of the foundation unit. The groove bottom is 100mm × 100mm. The gap between the bottom of the channel and the concrete is 150mm, and the inner diameter of the channel 17 is 80mm; the height of the connecting channel 4 is 0.8m and the inner diameter is 1.5m; the depth and width of the reserved ring channel 8 are 10cm; the concrete is poured according to the concrete mix proportion in Table 1 and conventionally cured. Samples of the resulting product were taken, and at 28 days of age, 16 test areas were uniformly sampled on the surface of the foundation using the rebound method. The estimated compressive strength of the concrete was above 40 MPa, meeting the C40 strength grade requirement. The maximum temperature difference and temperature stress of the foundation unit were calculated according to the "Standard for Construction of Mass Concrete GB 50496-2018" and are shown in Table 2.

[0051] Table 1: Concrete Mix Proportions

[0052]

[0053]

[0054] Table 2: Maximum Temperature Difference and Temperature Stress of Foundation Unit

[0055]

[0056] As can be seen from the results in Table 2, the maximum temperature difference between the inner and outer surfaces of the foundation unit of the present invention is 10.1℃. The small temperature difference and low temperature stress are beneficial to the stability of the foundation structure, and improve the load-bearing capacity, stiffness and durability, which is superior to the conventional square foundation unit structure.

[0057] Experiment 3

[0058] like Figure 4 The schematic diagram illustrates how, using the prefabricated foundation unit from Experiment 1, four foundation units are assembled into a single layer to form the entire foundation (approximately 8.4m × 8.4m × 2m) using the following construction method. The annular steel reinforcement cage has a cross-section of 40cm × 40cm, with its length determined by the encircling length. The mesh size is 200mm × 200mm, and the steel reinforcement diameter is 8mm. The steps are as follows:

[0059] 1) Within the environment enclosed by the cofferdam 13 and the bottom sealing concrete layer 9, the piles 6 are set to extend to the same height. Using hoisting equipment, the foundation unit is hoisted and lowered according to the set dimensions, so that the connecting groove 4 of the foundation unit is fitted with the corresponding pile 6. The height of the pile 6 extending from the bottom sealing concrete layer 9 is 2-3cm smaller than the height of the connecting groove 4, and the outer diameter of the pile 6 is 3-4cm smaller than the inner diameter of the connecting groove 4. The foundation unit is fitted with the pile 6 and is flush with and presses against the bottom sealing concrete layer 9. A 40cm wet joint is left between two adjacent foundation units. All the through holes 14 of the foundation units spliced ​​into the entire foundation are oriented in the same or parallel direction, which is conducive to the drainage and filling of sand during backfilling, or to partially leaving it on the ground to reduce the impact of airflow or water flow.

[0060] 2) Erect formwork 11 at the wet joint between two adjacent foundation units, insert steel bars with a diameter of 10mm into the duct 17, and at the same time, install an annular steel cage around the entire foundation to surround the lower part of the spliced ​​foundation, and erect formwork around the annular steel cage; wherein, multiple telescopic cylinders 12 are horizontally arranged inside the cofferdam 13 to push the vertically arranged formwork 11 to move horizontally, thereby controlling the distance between the formwork and the foundation unit and providing support for the formwork.

[0061] 3) Through the grouting inlet and outlet on the connecting groove 4, the pile foundation is grouted and tightly connected to the connecting groove 4. Simultaneously, concrete is poured into the wet joint and the annular reinforcing cage according to the concrete mix proportions in Table 1, forming a densely poured wet joint and reinforcing beam 10. After curing to the specified strength, the formwork can be removed. The estimated compressive strength of the concrete in the entire foundation, measured at 28 days of age using the rebound method in 16 uniformly sampled areas on the foundation surface, is also above 40 MPa, meeting the C40 strength grade requirement. The maximum temperature difference and temperature stress of the entire foundation, calculated according to the "Standard for Construction of Mass Concrete GB 50496-2018", are shown in Table 3.

[0062] Table 3: Maximum temperature difference and temperature stress of the entire foundation

[0063]

[0064] Experiment 4

[0065] See Figure 5The schematic diagram (showing only the splicing of two foundation units per floor) illustrates how, using the prefabricated foundation units from Experiment 1, two floors of 32 foundation units are spliced ​​together to form the entire foundation (approximately 17.2m × 17.2m × 4.4m). The annular steel reinforcement cage has a cross-section of 40cm × 40cm, its length determined by the encircling length, a mesh size of 200mm × 200mm, and a steel bar diameter of 8mm. The side wall steel reinforcement cage 19 has a cross-section of 80cm × 80cm, its height determined by the overall foundation height, a mesh size of 200mm × 200mm, and a steel bar diameter of 8mm. The steps are as follows:

[0066] 1) Within the environment enclosed by the cofferdam 13 and the bottom sealing concrete layer 9, the piles 6 are set to extend to the same height. Using hoisting equipment, the foundation unit is hoisted and lowered according to the set dimensions. First, the first layer is spliced, so that the connecting groove 4 of the foundation unit of the first layer is fitted with the corresponding pile 6. The height of the pile 6 extending from the bottom sealing concrete layer 9 is 2-3cm smaller than the height of the connecting groove 4, and the outer diameter of the pile 6 is 3-4cm smaller than the inner diameter of the connecting groove 4. The foundation unit is fitted with the pile 6 and is flat and pressed against the bottom sealing concrete layer 9. A 40cm wet joint is left between two adjacent foundation units. Then, the second layer is stacked and spliced ​​accordingly. A 40cm wet joint is left between two adjacent upper and lower foundation units. All the through holes 14 of the foundation units of the entire foundation are spliced ​​to have the same or parallel orientation, which is beneficial for the drainage and filling of sand during backfilling, or for partially leaving it on the ground to reduce the impact of airflow or water flow.

[0067] 2) Erect formwork for the wet joint between two adjacent foundation units, connect the upper duct 17 with the lower duct 17, and insert 10mm diameter steel bars into the duct 17 for connection. At the same time, install annular steel cages around the outer ring of the entire foundation for both layers, surround the lower part of each layer of the spliced ​​foundation, and erect formwork around the annular steel cages.

[0068] 3) At the arch feet on both sides of the entire pier, a side wall reinforcement cage 19 with a height 50cm lower than the height of the entire pier is lowered. The side wall reinforcement cage 19 is fixedly connected to the annular reinforcement cage of each layer. The template installed on both sides of the side wall reinforcement cage 19 is at the same height as the entire pier. The side wall reinforcement cage 19 is located between the side wall of the entire pier and the template. Among them, multiple telescopic cylinders 12 are horizontally arranged inside the cofferdam 13 to push the vertically arranged template to move horizontally, thereby controlling the distance between the template and the pier unit and providing support for the template.

[0069] 3) Through the grouting inlet and outlet on the connecting groove 4, the pile foundation is grouted and tightly connected to the connecting groove 4. Simultaneously, concrete is poured into the wet joint, the side wall reinforcement cage 19, and the annular reinforcement cage according to the concrete mix proportions in Table 1, forming a densely poured wet joint, reinforced column, and reinforced beam 10. After curing to the specified strength, the formwork can be removed. At 28 days of age, the estimated compressive strength of the concrete in 16 test areas uniformly sampled on the surface of the entire foundation using the rebound method is also above 40 MPa, meeting the C40 strength grade requirement. The maximum temperature difference and temperature stress of the entire foundation are calculated according to the "Standard for Construction of Mass Concrete GB 50496-2018", as shown in Table 4.

[0070] Table 4: Maximum temperature difference and temperature stress of the entire foundation

[0071]

[0072] As can be seen from the results in Tables 3 and 4, the precast foundation units of this invention, produced in large quantities and in a standardized manner at the prefabrication plant, significantly reduce on-site construction time. Furthermore, the internal and external arched structures and through-hole design of the precast foundation units help reduce overall temperature differences, promote structural rigidity, and result in foundations with strong overall compressive strength, good stability, and high load-bearing capacity. They also offer advantages such as lightweight construction, ease of on-site construction and transportation, and material savings, making them promising for widespread application and practical value.

[0073] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0074] 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 examples shown and described herein.

Claims

1. A prefabricated foundation structure, comprising multiple independent foundation units, wherein two adjacent foundation units can be fixedly connected, characterized in that, The foundation unit is a precast concrete square body with through holes, and the foundation unit includes: A bottom steel reinforcement cage is flatly embedded in the entire lower part of the foundation unit; An outer arched steel cage, which is an arc-shaped steel reinforcement connection structure, spans across and covers the bottom steel cage, and the two ends of the outer arched steel cage are connected to the bottom steel cage. Two inner arched steel cages, both with arc-shaped steel reinforcement connection structures, are located inside the outer arched steel cage and on the inner sides of the two arch feet of the outer arched steel cage, respectively. The inner arched steel cages overlap and are fixedly connected with the arc surface of the outer arched steel cage. The two inner arched steel cages span across and cover the two ends of the bottom steel cage, and the two ends of the inner arched steel cages are connected to the bottom steel cage. The central steel cage is fixed between the arch tops of the two inner arched steel cages; A connecting groove is used for nested connection with the foundation pile. The connecting groove is located at the center of the lower part of the foundation unit, between the arch feet of the two inner arched steel cages, and below the middle steel cage. The bottom steel cage surrounds the outer perimeter of the connecting groove. The connecting groove is provided with a grouting inlet and outlet that communicates with the outside. The height of the connecting groove is 1 / 3 to 1 / 2 of the height of the foundation unit. The bottom reinforcing cage, outer arched reinforcing cage, inner arched reinforcing cage, and middle reinforcing cage are all embedded in the foundation unit by concrete pouring; each foundation unit corresponds to a nested foundation pile, and the concrete poured for the two inner arched reinforcing cages and the middle reinforcing cage is poured to be flush with their arch tops, so that a through hole is formed between the upper surface of the middle reinforcing cage and the bottom surface of the outer arched reinforcing cage; a through hole is formed between the bottom surface of the inner arched reinforcing cage and the upper surface of the bottom reinforcing cage.

2. The prefabricated pier structure as described in claim 1, characterized in that, The specific structure that enables two adjacent support units to be fixedly connected is as follows: the connecting surface of the support unit is provided with a groove with a groove opening larger than the bottom of the groove, and a channel is provided from the upper surface of the support unit to the side wall of the groove, through which the groove can be connected to the outside.

3. The prefabricated pier structure as described in claim 2, characterized in that, The groove is a truncated quadrangular shape, and the connecting surface of the support unit and the bottom of the groove are provided with outwardly extending steel bars.

4. The prefabricated pier structure as described in claim 3, characterized in that, The lower part of the non-connecting surface of the foundation unit is provided with a reserved ring channel. The reserved ring channels of the spliced ​​foundation unit can be connected to the outer perimeter in sequence to form an outer ring around the entire foundation. This ring is used to install a ring-shaped steel cage, which surrounds the lower part of the spliced ​​foundation and is then cast to form a ring-shaped reinforcing beam.

5. A construction method for precast foundation structures, characterized in that, The application of the precast pier structure as described in any one of claims 1-4 includes the following steps: 1) Within the environment enclosed by the cofferdam and the bottom sealing concrete layer, the piles are set to extend to the same height. Using hoisting equipment, the foundation unit is hoisted and lowered according to the set dimensions, so that the connecting groove of the foundation unit fits onto the corresponding pile. The height of the pile extending from the bottom sealing concrete layer is 2-3cm smaller than the height of the connecting groove, and the outer diameter of the pile is 3-4cm smaller than the inner diameter of the connecting groove. The foundation unit fits onto the pile and is flush with and presses against the bottom sealing concrete layer. A 40-50cm wet joint is left between two adjacent foundation units. All the through holes of the foundation units spliced ​​into the entire foundation are oriented in the same or parallel directions. 2) Erect formwork for the wet joint between two adjacent foundation units, insert reinforcing bars into the ducts, and at the same time, install an annular reinforcing cage around the entire foundation to surround the lower part of the spliced ​​foundation, and erect formwork around the annular reinforcing cage. 3) Through the grouting inlet and outlet on the connecting groove, the pile foundation is grouted and tightly connected to the connecting groove. At the same time, concrete is poured into the wet joint and the ring steel cage to form a tightly poured wet joint and a reinforced beam. After curing to the specified strength, the formwork can be removed.

6. The construction method as described in claim 5, characterized in that, Step 2) also includes: horizontally installing multiple telescopic cylinders on the inner side of the cofferdam to push the vertically installed template to move horizontally.

7. The construction method as described in claim 6, characterized in that, For foundations that require splicing two layers of foundation unit height, the following is also included: A side wall reinforcement cage with a height 50cm lower than the overall height of the pier is placed at the arch feet on both sides of the entire pier. The side wall reinforcement cage is fixedly connected to the ring reinforcement cage of each layer. The template installed on the side wall reinforcement cage is at the same height as the entire pier. The side wall reinforcement cage is located between the side wall of the entire pier and the template, and then it is cast in place.

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