A PHC pipe pile and its manufacturing process

Abstract

A PHC pipe pile manufacturing process, comprising a first steel reinforcement cage bound by steel bars, a circular steel partition plate and a second steel reinforcement cage bound by steel bars placed in an outer mold in sequence; concrete is laid according to the volume of the first steel reinforcement cage and the second steel reinforcement cage respectively; the first steel reinforcement cage and the second steel reinforcement cage are formed into a mold to obtain a solid section concrete pile body corresponding to the first steel reinforcement cage section and a hollow section concrete pile body corresponding to the second steel reinforcement cage section; the amount of concrete laid for the first steel reinforcement cage fills the first steel reinforcement cage section; the amount of concrete laid for the second steel reinforcement cage does not fill the second steel reinforcement cage section, and the steel bar density of the first steel reinforcement cage is greater than that of the second steel reinforcement cage. The application also provides a PHC pipe pile, comprising the solid section concrete pile body and the hollow section concrete pile body obtained by the above process and a circular steel partition plate arranged therebetween; the application replaces manual core filling construction and solves the problems of complexity, long cycle, difficult construction, unstable pullout resistance, shear resistance and bearing capacity of traditional core filling.

Description

Technical Field

[0001] The invention belongs to the field of civil engineering pile foundations, and in particular relates to a PHC pipe pile and a manufacturing process thereof. Background Art

[0002] Prestressed high-strength concrete pipe piles (PHC pipe piles) have the characteristics of good pile body quality, high vertical bearing capacity of single piles, strong adaptability to engineering geological conditions, and fast construction speed. They have been widely used in construction, highway, railway, port and other projects. A large amount of earthquake damage investigation data and theoretical analysis have shown that under the action of strong earthquakes, the connection between the PHC pipe pile foundation and the pedestal is subjected to the combined action of the maximum axial force, shear force and bending moment. However, traditional PHC pipe piles have the characteristic of hollow cross-section. According to the results of theoretical analysis, the cross-sectional area of ​​the pipe pile body has a huge impact on the shear bearing capacity of the pile body. The small shear cross-sectional area of ​​the existing annular cross-section is precisely one of the shortcomings of pipe piles. Traditional wet concrete core-filled pipe piles can refer to 1. "Prestressed Concrete Pipe Piles," National Building Standard Design Atlas, compiled by the China Architecture Standard Design Research Institute, 10G409, Beijing, China Planning Press, August 2010; and 2. "Technical Standard for Prestressed Concrete Pipe Piles," JGJ / T406-2017, Implementation Standard, February 1, 2018, Ministry of Housing and Urban-Rural Development of the People's Republic of China. In actual engineering practice, to address the issue of low shear bearing capacity of the pile body, most PHC pile body core-filling measures are implemented on-site by filling the pipe hole with reinforced concrete. However, traditional wet concrete core-filling methods have the following problems:

[0003] 1. Traditional wet concrete core filling includes setting longitudinal steel bars and spiral stirrups in the core filling part, wet pouring concrete and other processes. The operation is cumbersome, the construction period is long, the construction is difficult to control, and the quality is difficult to ensure.

[0004] 2. When the groundwater level at the construction site is high, the holes of the PHC piles are filled with water, making wet core filling construction difficult to implement and ensuring the strength quality of the cast-in-place concrete.

[0005] 3. Under the current environmental protection pressure, the core filling part of the pipe hole is still cast on site, which causes more serious environmental pollution and does not meet the requirements of the current construction industrialization situation.

[0006] 4. Traditionally, the core fill is manually poured on-site, making it difficult to maintain and compressive strength difficult to guarantee. The core fill provides the foundation's pullout bearing capacity, primarily relying on the core fill's consolidation strength and the interfacial bond strength between the core fill and the inner wall of the pile. When concrete is poured on-site, neither the core fill's consolidation strength nor the interfacial bond strength can be guaranteed. The core fill, constructed on-site for PHC piles with reinforced concrete in the pipe hole, exhibits significant disparity in consolidation. Summary of the Invention

[0007] In order to solve the problems of the conventional wet core filling in the prior art, such as cumbersome production, long cycle, difficult construction control, difficult quality assurance, and unstable pull-out bearing capacity, and to promote the assembly construction of PHC pile foundations, especially in view of the existing problem of unstable pull-out bearing capacity, the present invention provides a production process for PHC piles, comprising:

[0008] Place the first steel cage tied with steel bars, the circular steel partition 2 and the second steel cage tied with steel bars in the external mold in sequence;

[0009] Distributing concrete according to the volumes of the first reinforcement cage and the second reinforcement cage respectively;

[0010] The first and second reinforcement cages are molded to obtain a solid concrete pile body 4 corresponding to the first reinforcement cage segment and a hollow concrete pile body 5 corresponding to the second reinforcement cage segment.

[0011] The amount of concrete in the first reinforcement cage is sufficient to fill the first reinforcement cage section with the concrete;

[0012] The amount of concrete in the second reinforcement cage is less than the amount of concrete filled in the second reinforcement cage section, and the steel density of the first reinforcement cage is greater than the steel density of the second reinforcement cage.

[0013] Preferably, the binding of the first reinforcement cage includes:

[0014] From the outside to the inside, longitudinal prestressed steel bars 6 and ordinary steel bars 8 are arranged in sequence;

[0015] The prestressed steel bars 6 are tied with outer spiral stirrups 7, and the ordinary steel bars 8 are tied with inner spiral stirrups 9 to obtain a first steel cage; and a circular steel end plate 1 is set at the other end of the prestressed steel bars 6 and the ordinary steel bars 8 away from the circular steel partition 2.

[0016] Preferably, the binding of the second reinforcement cage includes:

[0017] The prestressed steel bars 6 are tied with outer spiral stirrups 7 to obtain a second steel cage; and an annular steel end plate 3 is provided at the other end of the prestressed steel bars 6 and the outer spiral stirrups 7 away from the circular steel partition 2.

[0018] Preferably, the prestressed steel bars 6 are spiral groove steel bars for low relaxation prestressed concrete with a ductility of 35 grades, a tensile strength of not less than 1420 MPa, a diameter range of 5 to 20 mm, and a number range of 7 to 20 bars.

[0019] Preferably, the diameter of the prestressed steel bar 6 is one of 9 mm, 10.7 mm, 12.6 mm, or a combination thereof.

[0020] Preferably, the common steel bars 8 are HRB400 grade hot-rolled steel bars with a diameter ranging from 5 mm to 20 mm and a number ranging from 3 to 15.

[0021] Preferably, the diameter of the ordinary steel bar 8 is 18 mm and / or 20 mm.

[0022] Preferably, the step of performing a mold-forming operation on the first and second reinforcement cages after the materials are laid to obtain a solid concrete pile body 4 corresponding to the first reinforcement cage segment and a hollow concrete pile body 5 corresponding to the second reinforcement cage segment comprises:

[0023] The first and second steel cages after the fabric is completed are molded together, and the screws of the external mold are tightened from both sides of one end of the external mold toward the other end at the same time to close the mold;

[0024] After the mold is closed, tension the first and second steel cages according to their specifications and reinforcement quantity, tighten the anchors and then unload;

[0025] Fix the peripheral mold on the centrifugal equipment for centrifugal molding;

[0026] After centrifugal forming, the external mold is heated and maintained, and after maintenance, the mold is removed and cooled;

[0027] The solid concrete pile body 4 corresponding to the first reinforcement cage segment and the hollow concrete pile body 5 corresponding to the second reinforcement cage segment are obtained.

[0028] Based on the same inventive concept, the present invention also provides a PHC pipe pile, comprising: a solid concrete pile body 4 and a hollow concrete pile body 5 obtained by the above-mentioned manufacturing process through external mold processing, and a circular steel partition 2 arranged therebetween;

[0029] The solid concrete pile body 4 is made of a first steel cage and concrete filling the first steel cage segment.

[0030] The hollow section concrete pile body 5 is made of a second steel cage and concrete with a filling volume less than the full volume of the second steel cage section; and the steel density of the first steel cage is greater than the steel density of the second steel cage.

[0031] Preferably, the solid concrete pile body 4 includes longitudinal prestressed steel bars 6, outer spiral stirrups 7, ordinary steel bars 8 and inner spiral stirrups 9.

[0032] The outer spiral stirrups 7 are cylindrical and spirally wrapped around the longitudinal prestressed steel bars 6;

[0033] The inner layer spiral stirrups 9 are cylindrical and spirally wrapped around the inner layer ordinary steel bars 8;

[0034] The other end of the solid concrete pile body 4 away from the circular steel diaphragm 2 is provided with a circular steel end plate 1, and the two ends of the inner spiral stirrup 9 are respectively connected to the circular steel end plate 1 and the circular steel diaphragm 2.

[0035] Preferably, the longitudinal prestressed steel bars 6 are cylindrical straight bars, small holes are provided on the circular steel partition 2, and the longitudinal prestressed steel bars 6 pass through the small holes on the circular steel partition 2 and are distributed in the solid section concrete pile body 4 and the hollow section concrete pile body 5.

[0036] Preferably, the hollow concrete pile body 5 further includes an outer spiral stirrup 7.

[0037] The outer spiral stirrups 7 are cylindrical and spirally wrapped around the longitudinal prestressed steel bars 6. The density of the wrapping is less than the density of the outer spiral stirrups 7 and the inner spiral stirrups 9 in the solid concrete pile body 4.

[0038] An annular steel end plate 3 is provided at the other end of the hollow concrete pile body 5 away from the circular steel partition 2, and both ends of the longitudinal prestressed steel bar 6 are connected to the circular steel end plate 1 and the annular steel end plate 3 respectively.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention provides a process for manufacturing PHC pipe piles, comprising placing a first steel cage bound by steel bars, a circular steel partition 2, and a second steel cage bound by steel bars in an external mold in sequence; distributing concrete according to the volumes of the first and second steel cages; and performing a mold-forming operation on the first and second steel cages after distributing the concrete to obtain a solid concrete pile body 4 corresponding to the first steel cage segment and a hollow concrete pile body 5 corresponding to the second steel cage segment; wherein the amount of concrete distributed in the first steel cage is sufficient to fill the first steel cage segment; the amount of concrete distributed in the second steel cage is less than the amount of concrete filling the second steel cage segment, and the steel density of the first steel cage is greater than the steel density of the second steel cage. The present invention provides a process for manufacturing PHC pipe piles that solves the problems of the prior art in traditional wet core filling, such as cumbersome production, long cycle, difficult construction control, difficult quality assurance, and unstable pull-out bearing capacity, thereby promoting the assembly construction of PHC pipe pile foundations. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flow chart of a manufacturing process of a PHC pipe pile provided by the present invention;

[0042] Figure 2A schematic diagram of the structure of a PHC pipe pile provided by the present invention;

[0043] Figure 3 A schematic diagram of a top view of a circular steel end plate 1 provided by the present invention;

[0044] Figure 4 The present invention provides Figure 3 Schematic diagram of the cross-section structure in Figure 1-1;

[0045] Figure 5 A schematic diagram of a top view of a circular steel partition 2 provided by the present invention;

[0046] Figure 6 The present invention provides Figure 5 Schematic diagram of the structure of section 2-2;

[0047] Figure 7 A schematic diagram of the top view of the annular steel end plate 3 provided by the present invention;

[0048] Figure 8 The present invention provides Figure 7 Schematic diagram of the structure of section 3-3;

[0049] Figure 9 A schematic diagram of the reinforcement structure of a PHC pipe pile provided by the present invention;

[0050] Figure 10 The present invention provides Figure 2 Schematic diagram of the AA section structure of the middle L1 segment;

[0051] Figure 11 The present invention provides Figure 2 Schematic diagram of the BB cross-section structure of the middle L2 segment.

[0052] Description of Figure Numbers:

[0053] 1-circular steel end plate; 2-circular steel partition; 3-annular steel end plate; 4-solid section concrete pile body; 5-hollow section concrete pile body; 6-outer layer longitudinal prestressed steel bars; 7-outer layer spiral stirrups; 8-ordinary steel bars; 9-inner layer spiral stirrups; L1-solid section pile body; L2-hollow section pile body. DETAILED DESCRIPTION

[0054] As attached Figure 1As shown, the present invention provides a PHC pipe pile manufacturing process, comprising: placing a first steel cage bound by steel bars, a circular steel partition 2, and a second steel cage bound by steel bars in an external mold in sequence; distributing concrete according to the volumes of the first steel cage and the second steel cage respectively; performing a mold-forming operation on the first steel cage and the second steel cage after distributing the concrete to obtain a solid concrete pile body 4 corresponding to the first steel cage segment and a hollow concrete pile body 5 corresponding to the second steel cage segment; wherein the amount of concrete distributed in the first steel cage is sufficient to fill the first steel cage segment with the concrete; the amount of concrete distributed in the second steel cage is less than the amount of concrete filling the second steel cage segment, and the steel density of the first steel cage is greater than the steel density of the second steel cage. Based on the same inventive concept, as shown in the attached Figure 2 As shown, the present invention also provides a PHC pipe pile, which comprises a solid concrete pile body 4 and a hollow concrete pile body 5. A circular steel partition 2 is provided between the two sections. The solid section is equipped with a double layer of dense spiral stirrups (outer spiral stirrups 7 and inner spiral stirrups 9), with the outer layer being longitudinal prestressed steel bars 6 and the inner layer being ordinary steel bars 8. The hollow section is equipped with a single layer of undensified spiral stirrups 7 and longitudinal prestressed steel bars 6. The cross-section and reinforcement and stirrup ratio of the solid concrete pile body 4 are greater than those of the hollow concrete pile body 5. As a result, the PHC pipe pile has significantly improved shear, bending, and axial compression bearing capacities, meeting the comprehensive load-bearing requirements of the upper section of the pile foundation close to the ground. The present invention provides a PHC pipe pile, which replaces the manual core filling construction process. A solid concrete pile body 4 of the PCH pipe pile is obtained through a prefabrication process of the PCH pipe pile. The solid concrete pile body 4 solves the cumbersome on-site pouring production of the traditional wet core filling method, shortens the long construction period, and facilitates construction control. It ensures the consolidation quality of the PHC pipe pile and solves the problem of unstable pull-out bearing capacity of the PHC pipe pile. The upper half of the PHC pipe pile is the solid concrete pile body 4, which greatly improves the shear, bending and axial compression bearing capacities of the upper section of the PCH pipe pile body, thereby promoting the assembled construction of the PHC pipe pile foundation.

[0055] In order to better understand the present invention, the present invention is further described below with reference to the accompanying drawings and examples.

[0056] Example 1:

[0057] As attached Figure 1 As shown, the present invention provides a manufacturing process for a PHC pipe pile, which is generally produced in a prefabrication factory, comprising: placing a first steel cage bound by steel bars, a circular steel partition 2, and a second steel cage bound by steel bars in an external mold in sequence; wherein the diameter of the circular steel partition 2 and the diameter of the circular steel end plate 1 are consistent with the outer diameter of the PHC pipe pile, the other end of the solid pile body section L1 is connected to the circular steel end plate 1, and the other end of the hollow pile body section L2 is connected to the annular steel end plate 3.

[0058] The present invention provides a PHC pipe pile with simple factory prefabrication technology. A circular steel partition 2 is set at a specific position of the pipe pile body. Mixed concrete materials of different volumes are respectively filled on both sides of the circular steel partition 2. When the centrifugal device rotates at high speed, the section filled with concrete becomes a solid section of the concrete pile body 4, and the other section not filled with concrete becomes a hollow section of the concrete pile body 5.

[0059] Furthermore, as attached Figures 2 to 8 As shown, the circular steel end plate 1 and the circular steel partition plate 2 are both solid circular steel plates. Anchor holes are provided at the edges of the circular steel end plate 1 and the annular steel end plate 3. Circular holes are provided on the circular steel partition plate 2 corresponding to the anchor holes. The thickness of the circular steel end plate 1 is 20mm to 30mm, and the thickness of the circular steel partition plate 2 is 10mm.

[0060] Furthermore, the external mold still adopts the traditional PHC pipe pile cylindrical steel mold.

[0061] First, clean the round steel cylinder mold of the pipe pile, remove residues such as cement slag, and apply engine oil to the edge of the mold; clean the tensioning head and tail plates, tensioning anchor screws, and screw rings, and apply lubricating oil; after preparation, place the steel cage with circular steel end plates 1, circular steel partitions 2 and annular steel end plates 3 into the mold, and install the tensioning head plate. During the entire assembly process, the straightness of the outer layer of longitudinal prestressed steel bars 6 and the inner layer of ordinary steel bars 8 should be ensured. After inspection, concrete can be placed in the steel cage inside the pipe pile.

[0062] Concrete is distributed according to the volume of the solid section (between the circular steel end plate 1 and the circular steel partition 2) corresponding to the first steel cage and the hollow section (between the circular steel partition 2 and the annular steel end plate 3) corresponding to the second steel cage;

[0063] Then, the first reinforcement cage and the second reinforcement cage after the materials are laid out are subjected to a mold-closing operation to obtain a solid section concrete pile body 4 corresponding to the first reinforcement cage segment and a hollow section concrete pile body 5 corresponding to the second reinforcement cage segment;

[0064] The amount of concrete in the first reinforcement cage is sufficient to fill the first reinforcement cage section with the concrete;

[0065] The amount of concrete in the second reinforcement cage is less than the amount of concrete filled in the second reinforcement cage section, and the steel density of the first reinforcement cage is greater than the steel density of the second reinforcement cage.

[0066] In the present invention, as shown in the attached Figure 9As shown, the binding of the first steel cage includes: arranging dense longitudinal prestressed steel bars 6 and ordinary steel bars 8 in sequence from the outside to the inside; performing dense binding of outer spiral stirrups 7 on the outside or inside of the prestressed steel bars 6, especially at the position away from both ends of the first steel cage, and performing dense binding of inner spiral stirrups 9 on the outside or inside of the ordinary steel bars 8, especially at the position away from both ends of the first steel cage. After the binding is completed, the first steel cage is obtained.

[0067] When making the first reinforcement cage, the outer longitudinal prestressed steel bars 6 and the inner longitudinal ordinary steel bars 8 used in the PCH pipe pile are grouped in equal lengths according to the length of the PCH pipe pile;

[0068] Furthermore, as attached Figure 10 As shown, the solid concrete pile body 4 includes: an inner layer of the solid concrete pile body 4 and an outer layer of the solid concrete pile body 4;

[0069] The outer layer of the solid section concrete pile body 4 is consistent with the annular diameter of the hollow section concrete pile body 5, and the annular cylindrical hollow interior is the inner layer of the solid section concrete pile body 4; the outer layer of the solid section concrete pile body 4 includes an outer layer of longitudinal prestressed steel bars 6 and an outer layer of spiral stirrups 7; the two ends of the outer layer of longitudinal prestressed steel bars 6 are anchored on the anchor holes of the circular steel end plate 1 and the annular steel end plate 3, respectively, and then the pier head of the longitudinal bar is completely placed in the countersunk hole of the end plate; one end of the outer layer of longitudinal prestressed steel bars 6 passes through the reserved circular hole of the circular steel partition 2 and is distributed in the first steel cage and the second steel cage to ensure that the longitudinal steel bars 6 are continuous throughout.

[0070] As attached Figure 9 and 10 As shown, the inner layer of the solid concrete pile body 4 includes an inner layer of longitudinal ordinary steel bars 8 and an inner layer of spiral stirrups 9;

[0071] The two ends of the inner longitudinal steel bars 8 of the solid pile section of the solid section concrete pile body 4 corresponding to the first steel cage section are welded to the circular steel end plate 1 and the circular steel partition 2, and a circular steel end plate 1 is provided at the other end of the prestressed steel bars 6 and the ordinary steel bars 8 away from the circular steel partition 2.

[0072] The outer spiral stirrups 7 and inner spiral stirrups 9 are spot-welded to the outer longitudinal prestressed steel bars 6 and the inner longitudinal conventional steel bars 8, respectively, to form the first cage. After the cage is formed, the welds should be inspected for looseness and any loose welds should be securely fastened. The welded cage framework should be neatly stacked in groups according to the specifications of the PHC piles.

[0073] The outer layer of the solid concrete pile body 4 and the inner layer of the solid concrete pile body 4 are an integrally formed solid section of the solid concrete pile body 4 , and both have the same length of L1 .

[0074] Furthermore, the outer spiral stirrups 7 are cylindrical spiral stirrups, which are spirally wrapped in the annular space of the outer layer of the solid section. Their density is greater than the density of the spiral stirrups in the annular space of the hollow section concrete pile body 5. The center of the spiral wrapping is on the central axis of the PHC pipe pile. The spacing between the dense areas of the outer spiral stirrups 7 of the solid section of the solid section concrete pile body 4 is 45 mm.

[0075] Furthermore, the outer longitudinal prestressed steel bars 6 are cylindrical straight steel bars, which are distributed in the outer layer of the solid concrete pile body 4 along the axis of the PHC pile and connected to the inner ring of the outer spiral stirrups 7 at the edge of the axial direction.

[0076] Furthermore, the outer longitudinal prestressed steel bars 6 and the hollow section longitudinal prestressed steel bars 6 are integral full-length prestressed steel bars. The two ends of the outer longitudinal prestressed steel bars 6 are anchored on the anchor holes of the circular steel end plate 1 and the annular steel end plate 3 respectively, and the middle passes through the reserved circular hole of the partition plate 2 to ensure that the longitudinal steel bars 6 are continuous throughout the length, so as to facilitate the use of prestressed tensioning construction.

[0077] Furthermore, the circular steel end plate 1 is provided with anchoring circular holes equal in number to the outer longitudinal prestressed steel bars 6, and the circular steel partition plate 2 is provided with circular holes equal in number to the outer longitudinal prestressed steel bars 6, with a diameter of not less than 20 mm, to facilitate the passage of the outer longitudinal prestressed steel bars 6.

[0078] Furthermore, the annular steel end plate 3 is an annular circular plate with the same inner and outer diameters as the hollow pile body and a thickness of 20 mm to 30 mm. It is provided with anchor holes equal in number to the outer longitudinal prestressed steel bars 6 .

[0079] Furthermore, it is characterized in that the inner layer spiral stirrups 9 are cylindrical spiral stirrups made of HPB300 grade ordinary hot-rolled steel bars, which are spirally wrapped in the inner layer of the solid section. The spiral density is greater than the spiral stirrup density in the cylindrical space of the hollow section concrete pile body 5, and the center of the spiral wrapping is on the central axis of the PHC pipe pile.

[0080] Furthermore, it is characterized in that the inner layer ordinary steel bars 8 are cylindrical steel bars, distributed in the inner layer of the solid section concrete pile body 4 along the axis direction of the PHC pipe pile, and connected to the inner ring of the inner layer spiral stirrups 9 at the edge of the axial direction.

[0081] Furthermore, the inner longitudinal reinforcement is ordinary steel bars 8, and the ends of the inner longitudinal reinforcement are welded to the circular steel end plates 1 and the circular steel diaphragms 2. The inner spiral stirrups 9 and the outer spiral stirrups 7 are spot welded to the inner ordinary steel bars 8 and the outer longitudinal prestressed steel bars 6, respectively, to form a first reinforcement cage, also known as the first steel mesh cage.

[0082] In the present invention, as shown in the attached Figure 9 As shown, the tying of the second reinforcement cage includes:

[0083] The outer layer of spiral stirrups 7 are densely tied on the outside or inside of the prestressed steel bars 6, and after the tying is completed, a second steel cage, that is, a second steel mesh cage, is obtained; and an annular steel end plate 3 is set at the other end of the prestressed steel bars 6 and the outer layer of spiral stirrups 7 away from the circular steel partition 2.

[0084] Furthermore, as attached Figure 9 and attached Figure 11 As shown, the hollow section concrete pile body 5 includes an outer layer of longitudinal prestressed steel bars 6 and an outer layer of spiral stirrups 7; the outer layer of spiral stirrups 7 are cylindrical spiral stirrups, which are spirally wrapped in the annular space of the hollow section, and the center of the dense spiral wrapping is on the central axis of the PHC pipe pile. The spacing between the non-densified area of ​​the spiral stirrups of the hollow section concrete pile body 5 is 80 mm.

[0085] As attached Figure 9 and 11 As shown, the outer layer longitudinal prestressed steel bars 6 are arranged in the annular cylindrical space of the hollow section, distributed in the outer layer of the hollow section concrete pile body 5 along the axial direction of the PHC pipe pile, and connected to the inner ring of the outer layer spiral stirrups 7 at the edge in the axial direction; the length of the hollow section concrete pile body 5 is L2.

[0086] Furthermore, the outer spiral stirrups 7 are constructed from cold-drawn low-carbon steel wire for concrete products, with a diameter ranging from 2mm to 10mm. The spacing between the reinforced outer spiral stirrups 7 in the solid section is 45mm, while the spacing between the unreinforced spiral stirrups in the hollow section is 80mm. The inner spiral stirrups 9 in the solid section are HPB300 grade, ordinary hot-rolled steel bars.

[0087] Furthermore, the diameter of the outer spiral stirrup 7 is selected to be 4 mm or 5 mm.

[0088] As attached Figure 9 The steel bar density of the first steel cage is greater than that of the second steel cage, that is, the longitudinal prestressed steel bars 6 and the inner longitudinal ordinary steel bars 8 of the first steel cage are greater in longitudinal reinforcement ratio than the longitudinal prestressed steel bars 6 of the second steel cage; the stirrup ratio of the spirally wrapped outer spiral stirrups 7 and the inner spiral stirrups 9 of the first steel cage is greater than the stirrup ratio of the spirally wrapped outer spiral stirrups 7 of the second steel cage.

[0089] As attached Figure 9As described above, since the longitudinal reinforcement ratio and stirrup ratio of the above-mentioned first steel cage are greater than those of the second steel cage, that is, the longitudinal reinforcement ratio and stirrup ratio of the solid pile body L1 section are greater than those of the hollow pile body L2 section. Therefore, the cross-sectional shear, bending and axial compression bearing capacities of the solid pile body L1 section are significantly improved, which can meet the comprehensive load-bearing requirements of the upper section of the pile foundation close to the ground.

[0090] In the present invention, as shown in the attached Figure 10 The prestressed steel bars 6 are spiral groove steel bars for low relaxation prestressed concrete with a ductility of 35 (codenamed PCB-1420-35-L-HG), with a tensile strength of not less than 1420 MPa, a diameter range of 5 to 20 mm, and a number range of 7 to 20.

[0091] Furthermore, the diameter of the prestressed steel bar 6 can be selected from 9.0 mm, 10.7 mm and 12.6 mm.

[0092] In the present invention, the diameter of the prestressed steel bar 6 is one of 9 mm, 10.7 mm, and 12.6 mm, or a combination thereof.

[0093] In the present invention, as shown in the attached Figure 10 The common steel bars 8 are HRB400 grade hot-rolled steel bars with a diameter ranging from 5 mm to 20 mm and a number ranging from 3 to 15.

[0094] In the present invention, the diameter of the ordinary steel bar 8 is 18 mm and / or 20 mm.

[0095] When spreading concrete, the concrete is evenly and densely arranged in the cylindrical steel mold of the pipe pile. More concrete is placed on the first steel cage corresponding to the solid section so that the first steel cage section is filled with concrete; less concrete is placed on the second steel cage corresponding to the hollow section so that the second steel cage section is not completely filled with concrete. The filling volume standard is set according to the prefabricated pipe pile model.

[0096] In the present invention, as shown in the attached Figure 2 The method of performing a mold-forming operation on the first and second reinforcement cages after the materials are laid to obtain a solid concrete pile body 4 corresponding to the first reinforcement cage segment and a hollow concrete pile body 5 corresponding to the second reinforcement cage segment comprises:

[0097] Then, the first and second steel cages with the fabrics completed are closed, and the screws on the external mold, i.e., the cylindrical steel mold of the pipe pile, are tightened from both sides of one end of the cylindrical steel mold to the other end at the same time with a pneumatic machine to ensure that the mold is closed.

[0098] After the mold is closed, the outer layer of the longitudinal prestressed steel bars 6 of the pipe pile are tensioned; first, the jack is put in place and aligned with the mold hole of the cylindrical steel mold of the pipe pile, and the tensioning rod is aligned with the center of the cylindrical steel mold of the pipe pile. Tensioning is carried out according to the specifications and reinforcement amount of the first and second steel cages (tensioning is carried out according to the requirements of different pipe pile specifications and reinforcement amount). During the tensioning process, the pause shall not be less than 3 times. After the longitudinal reinforcement reaches the tensioning stress, the anchor nut shall be tightened, and the anchor shall be unloaded after the tensioning force is stabilized for 30 seconds.

[0099] After the tensioning is completed, the external mold (i.e. the cylindrical steel mold of the pipe pile) is hoisted and fixed on the running wheel of the centrifuge equipment. The process parameters of the centrifuge are set, and the pipe pile concrete is centrifugally formed according to the time and speed of "low speed-low medium speed 1-low medium speed 2-medium speed-high speed". The speed and time are appropriately adjusted according to the state of the concrete during placement.

[0100] After centrifugal forming, the concrete piles centrifugally formed in the external mold (i.e., the cylindrical steel mold for the pipe pile) are subjected to high-pressure heating and steam curing. The temperature rise is generally controlled within the range of 35 degrees per hour to minimize temperature fluctuations during the constant temperature stage and strictly follow relevant specifications. The temperature rises by 8 to 10 degrees in the first 30 minutes of the heating stage, and then by 18 to 22 degrees every half an hour until the steam curing temperature reaches 90 to 95 degrees. After the curing is completed, the external mold (i.e., the cylindrical steel mold for the pipe pile) is demolded. The cross-cross method is used during demolding to avoid bending and cracking of the external mold (i.e., the cylindrical steel mold for the pipe pile), which affects the solid and hollow sections of the PHC pipe pile in the mold. After demolding, cooling and curing are carried out.

[0101] After the formwork is removed and the concrete is cooled, a variable inner diameter prestressed high-strength concrete pile is obtained, which includes a solid concrete pile body 4 corresponding to the first reinforcement cage segment and a hollow concrete pile body 5 corresponding to the second reinforcement cage segment.

[0102] The cross-section of the pipe pile body of the present invention is circular in the solid section concrete pile body 4 and annular in the hollow section concrete pile body 5. The lengths of the solid section pile body and the hollow section pile body are set according to project requirements. The total length of a single PHC pipe pile body is 11 meters, of which the length of the solid section concrete pile body 4 is 3 to 5 meters. The cross-sectional dimensions of the circular cross-section and the annular cross-section of the PHC pipe pile body and the pile body concrete strength are also set according to specific project load-bearing requirements.

[0103] Furthermore, common pile outer diameters are one of 400 mm, 500 mm and 600 mm and a combination thereof, the corresponding wall thicknesses are 95 mm, 110 mm and 130 mm, and the pile body concrete strength is C80.

[0104] The cross-sectional area of ​​the solid concrete pile body 4 is greater than the cross-sectional area of ​​the hollow concrete pile body 5 .

[0105] Example 2:

[0106] Based on the same inventive concept, the present invention also provides a PHC pile, as shown in the attached Figure 2 As shown, it includes: a solid concrete pile body 4 and a hollow concrete pile body 5 obtained by the manufacturing process of the above embodiment through external mold processing and a circular steel partition 2 arranged therebetween;

[0107] The solid concrete pile body 4 is made of a first steel cage and concrete filling the first steel cage segment.

[0108] The hollow section concrete pile body 5 is made of a second steel cage and concrete with a filling volume less than the full volume of the second steel cage section; and the steel density of the first steel cage is greater than the steel density of the second steel cage.

[0109] In the present invention, as shown in the attached Figure 9 and 10 As shown, the solid concrete pile body 4 includes longitudinal prestressed steel bars 6, outer spiral stirrups 7, ordinary steel bars 8 and inner spiral stirrups 9.

[0110] The outer spiral stirrups 7 are cylindrical and spirally wrapped around the longitudinal prestressed steel bars 6;

[0111] The inner layer spiral stirrups 9 are cylindrical and spirally wrapped around the inner layer ordinary steel bars 8;

[0112] The other end of the solid concrete pile body 4 away from the circular steel diaphragm 2 is provided with a circular steel end plate 1, and the two ends of the inner spiral stirrup 9 are respectively connected to the circular steel end plate 1 and the circular steel diaphragm 2.

[0113] In the present invention, the longitudinal prestressed steel bars 6 are columnar straight bars, as shown in the attached Figure 5 and 6 As shown, small holes are provided on the circular steel partition 2 , and the longitudinal prestressed steel bars 6 pass through the small holes on the circular steel partition 2 and are distributed in the solid section concrete pile body 4 and the hollow section concrete pile body 5 .

[0114] In the present invention, as shown in the attached Figures 2 to 11 As shown, the hollow concrete pile body 5 also includes an outer spiral stirrup 7,

[0115] The outer spiral stirrups 7 are cylindrical and spirally wrapped around the longitudinal prestressed steel bars 6 . The wrapping density is lower than the density of the spiral wrapping of the outer spiral stirrups 7 and the inner spiral stirrups 9 in the solid concrete pile body 4 .

[0116] An annular steel end plate 3 is provided at the other end of the hollow concrete pile body 5 away from the circular steel partition 2, and both ends of the longitudinal prestressed steel bar 6 are connected to the small holes of the circular steel end plate 1 and the annular steel end plate 3 respectively.

[0117] Furthermore, the circular steel end plate 1, the circular steel partition plate 2 and the annular steel end plate 3 are generally made of Q235 steel. During production, their thickness is strictly checked and their surfaces are required to be bright and free of obvious cracks.

[0118] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0119] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0120] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A process for manufacturing a PHC pile, characterized in that: include: Placing a first steel cage bound by steel bars, a circular steel partition (2), and a second steel cage bound by steel bars in an external mold in sequence; Distributing concrete according to the volumes of the first reinforcement cage and the second reinforcement cage respectively; Performing a mold-closing operation on the first and second reinforcement cages after the materials are laid to obtain a solid concrete pile body (4) corresponding to the first reinforcement cage segment and a hollow concrete pile body (5) corresponding to the second reinforcement cage segment; The amount of concrete in the first reinforcement cage is sufficient to fill the first reinforcement cage section with the concrete; The amount of concrete in the second reinforcement cage is less than the amount of concrete in the second reinforcement cage section, and the steel density of the first reinforcement cage is greater than the steel density of the second reinforcement cage; The method of performing a mold-forming operation on the first and second reinforcement cages after the materials are laid to obtain a solid concrete pile body (4) corresponding to the first reinforcement cage segment and a hollow concrete pile body (5) corresponding to the second reinforcement cage segment comprises: The first and second steel cages after the fabric is completed are molded together, and the screws of the external mold are tightened from both sides of one end of the external mold toward the other end at the same time to close the mold; After the mold is closed, tension the first and second steel cages according to their specifications and reinforcement quantity, tighten the anchors and then unload; Fix the peripheral mold on the centrifugal equipment for centrifugal molding; After centrifugal forming, the external mold is heated and maintained, and after maintenance, the mold is removed and cooled; The heating rate of the heating curing is controlled within the range of 35 degrees per hour. The temperature is increased by 8 to 10 degrees in the first 30 minutes of the heating stage, and then increased by 18 to 22 degrees every half an hour until the steaming temperature reaches 90 to 95 degrees. Obtaining a solid concrete pile body (4) corresponding to the first reinforcement cage segment and a hollow concrete pile body (5) corresponding to the second reinforcement cage segment; The tying of the first reinforcement cage includes: Longitudinal prestressed steel bars (6) and ordinary steel bars (8) are arranged in sequence from the outside to the inside; The prestressed steel bars (6) are bound with outer spiral stirrups (7), and the ordinary steel bars (8) are bound with inner spiral stirrups (9) to obtain a first steel cage; and a circular steel end plate (1) is provided at the other end of the prestressed steel bars (6) and the ordinary steel bars (8) away from the circular steel partition plate (2); The tying of the second reinforcement cage includes: The prestressed steel bars (6) are tied with outer spiral stirrups (7) to obtain a second steel cage; and an annular steel end plate (3) is provided at the other end of the prestressed steel bars (6) and the outer spiral stirrups (7) away from the circular steel partition (2); The prestressed steel bars (6) are spiral groove steel bars for low relaxation prestressed concrete with a ductility of 35, a tensile strength of not less than 1420 MPa, a diameter range of 5 to 20 mm, and a number range of 7 to 20 bars; The diameter of the prestressed steel bar (6) is one of 9 mm, 10.7 mm, 12.6 mm, or a combination thereof; The ordinary steel bars (8) are HRB400 grade hot-rolled steel bars with a diameter range of 5 mm to 20 mm and a number range of 3 to 15; The diameter of the ordinary steel bar (8) is 18 mm and / or 20 mm.

2. A PHC pile, characterized in that: include: The manufacturing process of the PHC pipe pile as claimed in claim 1 comprises a solid concrete pile body (4) and a hollow concrete pile body (5) obtained by processing with an external mold, and a circular steel partition (2) arranged therebetween; The solid concrete pile body (4) is made of a first steel cage and concrete filling the first steel cage segment; The hollow section concrete pile body (5) is made of a second steel cage and concrete with a filling volume less than the full volume of the second steel cage section; and the steel density of the first steel cage is greater than the steel density of the second steel cage.

3. The PHC pile according to claim 2, characterized in that: The solid concrete pile body (4) comprises longitudinal prestressed steel bars (6), outer spiral stirrups (7), ordinary steel bars (8) and inner spiral stirrups (9). The outer spiral stirrups (7) are cylindrical and spirally wrapped around the longitudinal prestressed steel bars (6); The inner layer spiral stirrups (9) are cylindrical and spirally wrapped around the inner layer ordinary steel bars (8); A circular steel end plate (1) is provided at the other end of the solid concrete pile body (4) away from the circular steel partition (2), and the two ends of the inner spiral stirrup (9) are respectively connected to the circular steel end plate (1) and the circular steel partition (2).

4. The PHC pile according to claim 3, characterized in that: The longitudinal prestressed steel bars (6) are columnar straight bars. Small holes are provided on the circular steel partition (2). The longitudinal prestressed steel bars (6) pass through the small holes on the circular steel partition (2) and are distributed in the solid section concrete pile body (4) and the hollow section concrete pile body (5).

5. The PHC pile according to claim 4, characterized in that: The hollow section concrete pile body (5) further includes an outer layer of spiral stirrups (7), The outer spiral stirrups (7) are cylindrical and spirally wound around the longitudinal prestressed steel bars (6). The density of the spiral windings is less than the density of the spiral windings of the outer spiral stirrups (7) and the inner spiral stirrups (9) in the solid concrete pile body (4). An annular steel end plate (3) is provided at the other end of the hollow section concrete pile body (5) away from the circular steel partition (2), and both ends of the longitudinal prestressed steel bar (6) are respectively connected to the circular steel end plate (1) and the annular steel end plate (3).

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