A triangular pile with reinforcing ribs and a method of manufacturing the same

Abstract

The application discloses a triangular pile with reinforcing ribs and a preparation method thereof, and relates to the technical field of prefabricated concrete piles. The triangular pile comprises a solid prefabricated concrete pile body, the cross section of which is triangular, and the three corners are all provided with chamfers. The chamfer width of the top corner is smaller than the bottom edge width, so that the cross section forms a guiding cross section which is narrow at the top and wide at the bottom. At least one side of the pile body is provided with concave or convex reinforcing ribs in the longitudinal direction of the pile body. The reinforcing ribs at the same longitudinal position can be connected to each other to form annular grooves or protrusions which surround the pile body. A longitudinal grouting pipe is embedded in the pile body, which is used for high-pressure grouting to the pile bottom and the soil around the pile after the pile is sunk. The preparation method adopts an adjustable mold. The chamfer and the reinforcing rib specifications are adjusted by replacing the corner mold assembly and the reinforcing rib forming module. The steel reinforcement cage is put into the mold, the concrete is prepared, the concrete is poured and vibrated, the steam curing is carried out, and the pile is demolded and delivered. The application can reduce the pile sinking resistance, improve the side friction resistance and the bearing capacity, has the post-grouting reinforcement function, and is suitable for a wide range of applications.

Description

Technical Field

[0001] This invention relates to the field of precast concrete pile technology, and in particular to a triangular pile with reinforcing ribs and its preparation method. Background Technology

[0002] Precast concrete piles are widely used in building foundation engineering due to their advantages such as high bearing capacity, fast construction speed, and stable quality. Currently, the most commonly used precast piles in engineering are cylindrical piles, square piles, or pipe piles, which have relatively regular cross-sectional shapes, and the outer circumference of the pile body is usually a smooth surface or equipped with annular ribs.

[0003] However, the above-mentioned traditional precast piles have the following problems in practical applications:

[0004] First, the pile driving resistance is relatively high. During the pile driving process, conventional precast piles with circular or square cross-sections experience concentrated compression on the pile tip and surrounding soil, especially in harder soil layers or dense sand layers. This significantly increases the pile driving resistance, leading to reduced pile driving efficiency and even requiring larger pile driving equipment, thus increasing construction costs.

[0005] Second, the side friction resistance of the pile body is not fully utilized. Traditional precast piles rely mainly on the friction between the pile body and the soil to provide bearing capacity. For precast piles with smooth surfaces, their side friction resistance is relatively limited; even if some pile types are equipped with annular ribs, the rib structure is usually arranged around the entire pile body, with a simple structural form that is difficult to adjust flexibly according to actual stratum conditions, and it is easy to cause local stress concentration in specific soil layers, affecting the load-bearing performance of the pile body.

[0006] Third, the cross-sectional guidance is insufficient. Although precast piles with triangular cross-sections have appeared, their cross-sections are usually regular triangles or only have simple chamfering treatment in some areas. During the sinking process, the pile body lacks a clear guiding cross-section that is narrower at the top and wider at the bottom, making it difficult to effectively reduce the frictional resistance on the pile side while ensuring the penetration ability of the pile tip, thus limiting its applicability in complex geological conditions.

[0007] Fourth, the reinforcement effect of the pile tip and surrounding soil is limited. Traditional precast piles usually rely solely on the contact between the pile body and the soil to provide bearing capacity. For situations where the bearing layer at the pile tip is weak or the soil around the pile is disturbed, there is a lack of effective post-grouting reinforcement methods, which makes it difficult to further improve the bearing capacity of the pile foundation, especially in projects with high bearing capacity requirements.

[0008] In addition, existing precast pile molds are mostly fixed cross-section structures, which are difficult to adapt to flexible adjustments for different cross-sectional shapes and the arrangement of reinforcing ribs. Furthermore, the casting, vibration, and curing processes for irregular cross-sections are not yet perfect, resulting in unstable product quality.

[0009] To address the above problems, this invention proposes a triangular pile with reinforcing ribs and its preparation method. Summary of the Invention

[0010] The purpose of this invention is to provide a triangular pile with reinforcing ribs and its preparation method, so as to solve the problems of high pile driving resistance, insufficient utilization of pile body side friction resistance, insufficient cross-sectional guidance, lack of post-grouting reinforcement methods, poor mold adaptability, and complex preparation process in the prior art.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0012] On one hand, the present invention provides a triangular pile with reinforcing ribs, comprising:

[0013] The triangular pile is a solid precast concrete pile, and the cross-section of the triangular pile is a triangular section.

[0014] The three corners of the triangular cross-section are all chamfered, forming a top chamfer and two bottom chamfers respectively; wherein, the width of the top chamfer is less than the width of the remaining part of the bottom edge after the two bottom chamfers, so that the triangular pile cross-section forms a guide section that is narrow at the top and wide at the bottom;

[0015] In this article, "the width of the chamfer" refers to the length of the chamfer's hypotenuse for a beveled angle and the chord length of the chamfer's arc for a rounded angle; "the width of the remaining part of the bottom edge after being chamfered by two bottom corners" refers to the straight-line distance between the two bottom corner chamfer endpoints.

[0016] The mechanism by which the above-mentioned triangular cross-section design, which is narrower at the top and wider at the bottom, reduces pile driving resistance is as follows: Compared with traditional triangular piles with uniform cross-section, the cross-section with a narrower top and wider bottom forms a guiding cross-section during the pile driving process. This guiding cross-section structure can guide the soil around the pile to spread out to both sides and downwards along the inclined surface of the pile side, reducing the end resistance that the pile end needs to overcome to directly penetrate the soil. At the same time, since the pile body cross-section gradually narrows from bottom to top, the lateral compression of the pile body by the soil side is reduced compared with piles with uniform cross-section, and the growth rate of the pile side friction is slowed down, thereby effectively reducing the overall penetration resistance throughout the entire pile driving process.

[0017] On at least one side of the triangular pile, concave or convex reinforcing ribs are provided at intervals along the longitudinal direction of the pile body; wherein, the concave or convex direction of the reinforcing ribs is perpendicular to the side on which they are located.

[0018] At least one grouting pipe is pre-embedded inside the triangular pile body, and the grouting pipe extends longitudinally along the pile body and penetrates the triangular pile body.

[0019] The triangle can be any triangle, but in a preferred embodiment, the triangle is an isosceles triangle or an equilateral triangle.

[0020] Preferably, the chamfer is a rounded corner or a beveled corner; in this invention, chamfer is a general term for both beveled corners and rounded corners, and does not specifically refer to a beveled corner.

[0021] Meanwhile, the lengths of the three sides of the triangle, as well as the form and size of each chamfer, can be designed and adjusted according to actual engineering needs.

[0022] Preferably, the distance between two adjacent reinforcing ribs on the same side is 0.5 meters to 1.5 meters;

[0023] As a special implementation, when the three sides are provided with the reinforcing ribs and are spaced at the same interval, the reinforcing ribs on the three sides located in the same longitudinal position are connected to each other by the reinforcing rib connecting sections provided at the chamfer, forming a ring-shaped protrusion around the pile body, thus forming a triangular bamboo joint pile.

[0024] Preferably, the grouting pipe has at least one of the following two structures:

[0025] The first type: The lower end of the grouting pipe extends to the bottom of the pile and is provided with a grout outlet, which is used to inject high-pressure grout into the bottom of the pile and the surrounding soil after the pile is driven into the pile; the grout outlet has a one-way check structure; wherein, the one-way check structure only allows the grout to be injected outward, automatically blocking the reverse flow of concrete or grout into the pipe, preventing pipe blockage and ensuring the effectiveness of grouting.

[0026] The second method involves a grouting pipe with at least one grout outlet near the outer periphery of the pile body. A ruptureable sealing element is installed at each outlet, which ruptures when the grouting pressure reaches a set value, injecting grout into the surrounding soil. During pile driving and pouring, the ruptureable sealing element seals the outlet, preventing blockage by mud, water, or concrete. During grouting, when the grouting pressure reaches the set value, the sealing element ruptures, allowing grout to be ejected at high pressure from the outlet and diffuse into the surrounding soil, thereby improving the grouting effect.

[0027] On the other hand, the present invention provides a method for preparing a triangular pile with reinforcing ribs, which includes the following steps:

[0028] S1. Preparation and adjustment of molds: Provide adjustable molds for triangular piles, and select and install the appropriate specifications of corner mold components according to the target pile type;

[0029] The adjustable mold includes a mold body, and the mold body has a mold cavity with a triangular cross-section. The top width of the mold cavity is smaller than the bottom width, so that the cross-section of the formed pile body forms a guide section that is narrow at the top and wide at the bottom.

[0030] The mold body has detachable corner mold components at three corners for forming chamfers of different curvatures, angles or lengths;

[0031] A side reinforcing rib forming structure is detachably installed on at least one inner side of the mold body. The side reinforcing rib forming structure is provided with reinforcing rib protrusions protruding into the mold cavity or reinforcing rib grooves recessed into the mold cavity. By replacing reinforcing rib forming structures of different specifications, the spacing and / or depth of the reinforcing ribs can be adjusted.

[0032] The corner mold assembly is equipped with a detachable corner reinforcing rib forming structure, which is either a corner reinforcing rib protrusion or a corner reinforcing rib groove. When the corner reinforcing rib forming structure is installed, the side reinforcing rib forming structures of the corner reinforcing rib forming structure are aligned and connected, so that the pile body forms an annular reinforcing rib around the pile body. When the corner reinforcing rib forming structure is removed, the annular reinforcing rib is broken at the corner, so that the pile body forms an independent reinforcing rib only on the side, and the chamfer remains smooth.

[0033] S2. Reinforcing cage processing and placement: A reinforcing cage matching the triangular cross-section is tied, the reinforcing cage including longitudinal main bars and spiral stirrups; grouting pipes are pre-embedded in the reinforcing cage, and triangular cross-section positioning clamps are installed; the tied reinforcing cage is hoisted into the mold and fixed in the mold cavity by the positioning clamps; wherein, the longitudinal main bars are ordinary reinforcing bars or prestressed reinforcing bars; when the longitudinal main bars are ordinary reinforcing bars, prestressing is not applied; when the longitudinal main bars are prestressed reinforcing bars, prestressing is applied.

[0034] S3. Concrete mix design: Prepare concrete with a strength grade of not less than C40, wherein the concrete includes cement, mineral admixtures, coarse and fine aggregates and additives;

[0035] S4. Pouring and Vibrating: The prepared concrete is poured into the mold cavity in layers from the top narrow side direction. Each layer is vibrated with an immersion vibrator. During vibration, the three corner areas of the mold cavity and the corresponding positions of the reinforcing rib forming structure are vibrated. The connection between the corner reinforcing rib forming structure and the side reinforcing rib forming structure is vibrated a second time. The vibrator needs to penetrate into the lower layer of concrete until the concrete fills the mold cavity and is compacted.

[0036] S5. Steam curing: The cast-in-place pile body is subjected to zoned temperature-controlled steam curing. The zoned temperature-controlled steam curing system sets up independent temperature control zones for the corner area and the middle area of ​​the triangular cross-section. Different heating rates and constant temperatures are used for curing the corner area and the middle area. The heating rate of the corner area is lower than that of the middle area, and the constant temperature of the corner area is lower than that of the middle area.

[0037] S6. Demolding and Shipment: After curing, first remove the corner mold components, then separate the side molds, demold, and inspect the pile body according to the standards. Only after passing the inspection will the pile be shipped out of the factory.

[0038] Preferably, in step S2, the grouting pipe is fixed to the reinforcing cage by binding or clamping; when pile bottom grouting is used, the lower end of the grouting pipe extends to the pile bottom and is provided with a grout outlet; when pile side grouting is used, the grouting pipe wall is provided with a grout outlet hole, and a ruptureable sealing component is provided at the grout outlet hole.

[0039] Preferably, when the longitudinal main reinforcement is prestressed steel bar, between steps S2 and S3, tensioning plates are installed at both ends of the mold cavity to apply prestress to the longitudinal main reinforcement in the steel cage to control the tension stress value and anchor it to the tensioning plate; after steam curing is completed in step S5, the prestress is released and the mold is removed.

[0040] Preferably, the prestressing is released after the concrete strength has reached more than 75% of the design strength.

[0041] Preferably, in step S4, the pouring depth of each layer of concrete is controlled within 300mm. The vibrator is inserted quickly and withdrawn slowly and vertically into the concrete, with an insertion depth of 50~100mm. Vibration is stopped when the concrete no longer sinks significantly, the surface is covered with slurry, and no large number of air bubbles escape. Vibration of the upper layer of concrete must be completed before the initial setting of the lower layer of concrete.

[0042] In step S5, due to the structural characteristics of a triangular cross-section—high concrete density at the corners and relatively uniform thickness at the center—the heat of hydration release and heat accumulation rate in the corner region are significantly higher than in the center region during steam curing. If the corners and center regions are heated at the same rate and constant temperature, a large temperature gradient will form between them, leading to uneven volume expansion between the corner and center concrete. This, in turn, causes temperature stress concentration. When the temperature stress exceeds the tensile strength of the corner concrete, microcracks or even through-cracks will occur, severely affecting the durability and structural strength of the pile. This invention addresses the aforementioned thermodynamic characteristics of the triangular cross-section by using a lower heating rate and lower constant temperature in the corner region, where heat accumulation is likely, and a relatively higher heating rate and constant temperature in the center region, where heat dissipation is better. This differentiated temperature control synchronizes the temperature changes across the triangular cross-section, reducing the temperature difference between the corners and center, thereby eliminating or significantly reducing temperature stress, preventing corner cracking, and ensuring the curing quality of irregularly shaped cross-section piles.

[0043] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0044] This invention features low pile driving resistance and strong penetration capability. By designing the pile cross-section as a triangle and chamfering the three corners, a guide section shape with a narrow top and wide bottom is formed at the pile end. During pile driving, this guide section guides the surrounding soil to spread along the inclined surface of the pile side, reducing the pile end penetration resistance. At the same time, as the cross-section gradually narrows from bottom to top, the squeezing effect of the soil on the pile body is weakened, and the increase of pile side friction is slowed down, resulting in a significant reduction in overall pile driving resistance. Especially in harder soil layers or dense sand layers, the penetration resistance of the guide section pile is more advantageous than that of the uniform cross-section pile, effectively reducing the difficulty and energy consumption of pile driving construction.

[0045] This invention significantly improves the side friction resistance of the pile body. By setting concave or convex reinforcing ribs at intervals along the longitudinal direction of the pile body on at least one side of the triangular pile body, a concave or convex pile-soil contact surface is formed on the side of the pile body, which effectively increases the contact area between the pile body and the soil and forms a mechanical interlocking effect at the pile-soil interface, thereby enhancing the side friction resistance of the pile body and improving the bearing capacity of a single pile.

[0046] The cross-section of this invention is highly adaptable and can meet different engineering needs. The triangular cross-section can be an equilateral triangle or an isosceles triangle, and the chamfers at the three corners can be rounded or beveled. The chamfer length can be adjusted according to actual needs, so that the pile cross-section can flexibly adapt to different geological conditions and bearing capacity requirements.

[0047] This invention has a post-grouting reinforcement function. By pre-embedding a grouting pipe inside the pile body, with the lower end of the grouting pipe extending to the bottom of the pile and having a grout outlet, or with a grout outlet hole with a ruptureable sealing device on the pipe wall, high-pressure grouting can be performed on the bottom of the pile and the soil around the pile after the pile body is driven, which further improves the bearing capacity of the pile end and the frictional resistance of the pile side, and improves the overall stress performance of the pile foundation.

[0048] The present invention features a flexible manufacturing process and a highly adjustable mold. By using an adjustable mold, the curvature, angle, or length of the chamfer, as well as the spacing and protrusion height of the reinforcing ribs, can be adjusted by replacing different specifications of the corner mold components and reinforcing rib forming modules. This allows for the production of multiple specifications of piles from a single mold, reducing mold manufacturing costs and improving production efficiency and product adaptability.

[0049] The pile body of this invention has stable and reliable quality. Through process control such as layered pouring, key vibration of concrete in the corner area and the reinforcing rib forming area, zoned temperature-controlled steam curing, and release of prestressing after the concrete strength reaches more than 75% of the design strength, the compactness and structural strength of the irregular cross-section pile body are effectively guaranteed, and the product quality is stable.

[0050] This invention features a curing process with good adaptability and reliable product quality. Addressing the structural characteristics of triangular cross-section piles—heat accumulation at the corners and rapid heat dissipation at the sides and center—it employs a steam curing strategy with independent temperature control for the corners and sides / center. The corner areas utilize a lower heating rate and constant temperature to prevent cracks caused by temperature stress concentration. The sides / center areas utilize a relatively higher heating rate and constant temperature, ensuring overall curing efficiency and achieving uniform temperature across the irregular cross-section. This effectively improves the finished product qualification rate and long-term durability of the triangular piles. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of a triangular bamboo-shaped pile with concave reinforcing ribs provided in an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the triangular bamboo-shaped pile with outwardly protruding reinforcing ribs provided in an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of a triangular pile structure with differentiated concave reinforcing rib spacing provided in an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of the rear side of a triangular pile with differentiated concave reinforcing rib spacing provided in an embodiment of the present invention;

[0055] Figure 5 This is a schematic diagram of a method for preparing a triangular pile with reinforcing ribs according to an embodiment of the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Example 1: A triangular pile with an irregular triangular cross-section and differentiated reinforcing rib spacing

[0058] This embodiment provides a triangular pile with reinforcing ribs, including a triangular pile body. The triangular pile body is a solid precast concrete pile with an irregular triangular cross-section, meaning that the three sides are not equal in length. In this embodiment, the total length of the pile body is 12m.

[0059] In this embodiment, the cross-section of the triangular pile is an irregular triangle with a base of 400mm, a left side of 500mm, and a right side of 450mm. All three chamfers are beveled. Specifically, at the apex, 50mm is cut off from both the left and right sides to form the beveled angle. Using the law of cosines, the calculated width of the beveled angle at the apex is approximately 41.8mm. Similarly, at the lower left base, 40mm is cut off from both the base and left side to form the lower left beveled angle; and at the lower right base, 30mm is cut off from both the base and right side to form the lower right beveled angle (the term "cut off" is used here to illustrate the cross-sectional shape; in reality, this triangular pile is generated in one pour using a mold). Clearly, the width of the apex beveled angle (41.8mm) is less than the remaining width (330mm) of the base after the two bottom bevels, creating a guide section that is narrower at the top and wider at the bottom.

[0060] Reinforcing ribs are only provided on the three sides of the triangular pile, with no reinforcing ribs provided on the chamfered corner. Recessed reinforcing ribs are spaced at intervals along the longitudinal direction of the pile on all three sides of the triangular pile. The direction of the indentation of the reinforcing rib is perpendicular to the side it is located on. In this embodiment, the depth of the indentation of the reinforcing rib is 30mm, and the width is 50mm. The spacing between the reinforcing ribs on the three sides is different: the spacing between two adjacent reinforcing ribs on the first side is 0.5m, the spacing between two adjacent reinforcing ribs on the second side is 1.0m, and the spacing between two adjacent reinforcing ribs on the third side is 1.5m. The reinforcing ribs on the three sides are staggered in the longitudinal direction of the pile.

[0061] At least one grouting pipe is pre-embedded inside the triangular pile body, extending longitudinally along the pile body and penetrating the triangular pile body. In this embodiment, there is one grouting pipe, which is located at the geometric center of the pile body cross-section. The lower end of the grouting pipe extends to the bottom of the pile and is provided with a grout outlet, which is used to perform high-pressure grouting to the bottom of the pile and the surrounding soil after the pile body is driven into the ground.

[0062] In this embodiment, the triangular pile has a triangular cross-section at the pile end, and all three corners are chamfered, forming a guide shape that is narrow at the top and wide at the bottom. This facilitates soil dispersion along the pile side, reduces pile driving resistance, and results in high pile driving efficiency. Each of the three sides is equipped with concave reinforcing ribs at varying intervals, allowing for flexible arrangement based on the stress characteristics of different sides of the pile. This increases the pile's side friction resistance while improving its adaptability to stress in different directions. Furthermore, the irregular triangular cross-section allows for the installation of reinforcing ribs on one or more sides of the pile, depending on the production process and mold configuration (see Embodiment 2), further enhancing the pile's adaptability to complex working conditions. After pile driving is completed, high-pressure grouting can be performed on the pile bottom and surrounding soil through a grouting pipe to further improve the pile end bearing capacity and side friction resistance, thereby improving the overall load-bearing performance of the pile foundation.

[0063] Example 2: A triangular pile with a single-sided reinforcing rib

[0064] The difference between this embodiment and embodiment 1 is that the reinforcing rib is only set on one side of the triangular pile, and no reinforcing rib is set on the other two sides.

[0065] In this embodiment, reinforcing ribs are disposed on one side of the triangular pile body and are arranged at intervals along the longitudinal direction of the pile body. The reinforcing ribs are concave reinforcing ribs with a depth of 30mm and a width of 50mm, and the distance between two adjacent reinforcing ribs is 1.0m.

[0066] The remaining structures, including the cross-sectional shape of the triangular pile, the chamfering form, the arrangement of the grouting pipes, and the recessed direction and size of the reinforcing ribs, are the same as in Example 1 and will not be described again.

[0067] This embodiment of the triangular pile features a reinforcing rib on only one side, making it suitable for engineering scenarios where a significant increase in side friction resistance is needed on one side of the pile, while maintaining low driving resistance on the other sides. The single-sided reinforcing rib effectively increases the pile-soil contact area and mechanical interlocking on that side, while reducing structural changes on the other sides, thus helping to control driving resistance and maintain pile stress balance. After pile driving is completed, high-pressure grouting can be performed on the pile bottom and surrounding soil through a grouting pipe to further enhance the pile tip bearing capacity and side friction resistance, thereby improving the overall load-bearing performance of the pile foundation.

[0068] Example 3: A triangular pile with an equilateral triangular cross section and rounded chamfers.

[0069] The difference between this embodiment and Embodiment 1 is that the cross-section of the triangular pile is an equilateral triangle, and all three chamfers are rounded. The grouting pipe is a side-grouting system with grout outlet holes on the pipe wall. In this embodiment, the total length of the pile is 12m.

[0070] In this embodiment, the front side length of the triangular pile body is 500mm. All three corners of the triangular pile body are rounded, and the width of each rounded corner is 80mm (referring to the chord length). The chord of the top chamfered arc is horizontal, and the chord of the bottom chamfered arc forms a 60-degree angle with the horizontal, ensuring that the three surfaces after cutting remain equal (340mm). The width of the top chamfer is less than the width of the remaining portion of the bottom edge after the two bottom chamfers, creating a guide section that is narrower at the top and wider at the bottom.

[0071] The triangular pile has recessed reinforcing ribs spaced longitudinally along its three sides. The recesses of the reinforcing ribs are perpendicular to the side they are located on. In this embodiment, the recess depth of the reinforcing ribs is 30 mm and the width is 50 mm. The spacing between the reinforcing ribs on the three sides is different: the spacing between two adjacent reinforcing ribs on the first side is 0.5 m, the spacing between two adjacent reinforcing ribs on the second side is 1.0 m, and the spacing between two adjacent reinforcing ribs on the third side is 1.5 m. The reinforcing ribs on the three sides are staggered in the longitudinal direction of the pile.

[0072] At least one grouting pipe is pre-embedded inside the triangular pile, extending longitudinally and penetrating the pile. In this embodiment, there is a single grouting pipe positioned near one of its sides, with the grout outlet on the pipe wall facing the soil around that side to ensure the grout can be directly sprayed and diffused into the surrounding soil. The grouting pipe wall has a grout outlet near the outer periphery of the pile. A ruptureable sealing element is installed at the grout outlet, which is used to rupture and open the outlet when the grouting pressure reaches a set value, allowing for high-pressure grouting into the surrounding soil. In this embodiment, the ruptureable sealing element is made of a brittle plastic sheet with a rupture pressure set at 2.0 MPa to 4.0 MPa. The sealing component is fixed to the outside of the grout outlet by bonding or hot melting. It can seal the grout outlet during the pile driving and pouring stages to prevent mud or concrete from clogging the channel. When high-pressure grouting is carried out after the pile is driven, the sealing component will break on its own when the grouting pressure reaches the set value. The grout will be sprayed out from the grout outlet under high pressure and spread to the soil around the pile, thereby improving the pile side friction and the overall bearing capacity of the pile foundation.

[0073] The triangular pile in this embodiment has a good geometric symmetry due to its equilateral triangular cross-section, which is beneficial for the force balance and guiding stability of the pile body during the pile driving process. All three chamfers are rounded, resulting in a smoother contact between the pile corners and the soil during driving, reducing stress concentration at the corners and lowering the risk of corner damage. The reinforcing ribs on the three sides are spaced differently, allowing for flexible arrangement according to the stress characteristics of different sides of the pile in the actual strata, increasing the pile's side friction resistance while improving its adaptability to non-uniform lateral loads. After pile driving is completed, high-pressure grouting can be performed on the pile bottom and surrounding soil through grouting pipes to further improve the pile tip bearing capacity and side friction resistance, thus improving the overall load-bearing performance of the pile foundation.

[0074] Example 4: A triangular bamboo-joint pile with an equilateral triangular cross section and annular concave reinforcing ribs.

[0075] This embodiment provides a triangular pile with reinforcing ribs, which differs from Embodiment 3 in that the concave reinforcing ribs on the three sides are spaced at the same distance, and the concave reinforcing ribs located in the same longitudinal position are interconnected to form an annular groove around the pile body, constituting a triangular bamboo-joint pile. In this embodiment, the total length of the pile body is 12m.

[0076] See Figure 1 , Figure 1 This is a schematic diagram of the structure of a triangular bamboo-shaped pile with concave reinforcing ribs provided in an embodiment of the present invention. Specifically, the triangular pile body is a solid precast concrete pile with an equilateral triangle cross-section. All three corners are rounded. Concave reinforcing ribs are provided on the three sides and the rounded corners. The reinforcing ribs are spaced at the same intervals and are connected to each other in the same longitudinal position to form an annular groove around the pile body. A grouting pipe is pre-embedded inside the pile body.

[0077] In this embodiment, the front side length of the triangular pile body is 500mm. All three corners of the triangular pile body are rounded, and the width of each rounded corner is 80mm (referring to the chord length). The chord of the top chamfer is horizontal, and the chord of the bottom chamfer is at a 60-degree angle to the horizontal, ensuring that the three surfaces after the cut are still equal (340mm). The width of the top chamfer is less than the width of the remaining portion of the bottom edge after the two bottom chamfers, creating a guide section that is narrower at the top and wider at the bottom.

[0078] The triangular pile has inwardly recessed reinforcing ribs spaced longitudinally along its three sides and chamfer. The recessed direction of the reinforcing ribs is perpendicular to the side they are located on. In this embodiment, the recess depth of the reinforcing ribs is 30mm and the width is 50mm. The reinforcing ribs on the three sides are spaced equally, with a distance of 1.0m between adjacent ribs. The reinforcing ribs on the three sides located in the same longitudinal position are interconnected by reinforcing rib connecting sections at the chamfer, forming an annular groove surrounding the triangular pile, giving the pile a bamboo-like structure.

[0079] At least one grouting pipe is pre-embedded inside the triangular pile body, extending longitudinally along the pile body and penetrating the triangular pile body. In this embodiment, there is one grouting pipe, which is located at the geometric center of the pile body cross-section. The lower end of the grouting pipe extends to the bottom of the pile and is provided with a grout outlet, which is used to perform high-pressure grouting to the bottom of the pile and the surrounding soil after the pile body is driven into the ground.

[0080] The triangular bamboo-joint pile in this embodiment has an equilateral triangular cross-section, resulting in a more uniform stress distribution on its three sides. The reinforcing ribs on the three sides connect to each other in the same longitudinal position to form annular grooves, creating multiple continuous annular friction interfaces between the pile and the soil. This further increases the pile side friction resistance compared to Embodiments 1 and 2, significantly enhancing the single pile bearing capacity. Simultaneously, the annular grooves continuously compact the soil around the pile during pile driving, improving its mechanical properties. After pile driving is completed, high-pressure grouting can be performed on the pile bottom and surrounding soil through a grouting pipe to further improve the pile tip bearing capacity and pile side friction resistance, thus improving the overall stress performance of the pile foundation.

[0081] Example 5: Schematic diagram of a triangular pile structure with differentiated concave reinforcing rib spacing.

[0082] The difference between this embodiment and embodiment 4 is that the spacing between the concave reinforcing ribs in this embodiment is different, and the reinforcing ribs are not connected to each other and are formed in an interlaced manner.

[0083] See Figure 3 , Figure 3 This is a schematic diagram of a triangular pile structure with differentiated concave reinforcing rib spacing provided in an embodiment of the present invention. In the diagram, the reinforcing ribs on the left and right sides of the triangular pile are interlocked but not connected. (See also...) Figure 4 , Figure 4 This is a schematic diagram of the rear side of a triangular pile with differentiated concave reinforcing rib spacing provided in an embodiment of the present invention; the rear side has only one concave reinforcing rib, which is not connected to the concave reinforcing ribs on the left and right sides, and the three concave reinforcing ribs form an interlaced structure.

[0084] With the aforementioned staggered arrangement, the concave reinforcing ribs on different sides of the pile will not form a continuous circumferential weakening surface within the same horizontal section, thus avoiding a reduction in pile section stiffness due to the continuous presence of circumferential grooves. Simultaneously, the concave reinforcing ribs on each side can still increase the contact area between that side and the soil, improving the pile's side friction resistance. Furthermore, because the concave reinforcing ribs are staggered, the forces on the pile in each direction are more dispersed during pile driving, which is beneficial for improving the pile's adaptability to non-uniform lateral loads. In addition, the staggered arrangement of the concave reinforcing ribs reduces the amount of concrete missing within the same section, helping to ensure the overall structural strength of the pile and reducing the risk of cracking due to excessive weakening of local sections. This structure is suitable for engineering scenarios requiring differentiated improvement of side friction resistance on each side while controlling the weakening of the pile section.

[0085] Example 6: A triangular bamboo-joint pile with an equilateral triangular cross section and annular outward-convex reinforcing ribs.

[0086] The difference between this embodiment and embodiment 4 is that the reinforcing rib in this embodiment is an outwardly convex reinforcing rib;

[0087] See Figure 2 , Figure 2 This is a schematic diagram of the structure of a triangular bamboo-shaped pile with externally protruding reinforcing ribs provided in an embodiment of the present invention. Specifically, the triangular pile body is a solid precast concrete pile with an equilateral triangular cross section. All three corners are rounded. Externally protruding reinforcing ribs are provided on the three sides and the rounded corners. The reinforcing ribs are spaced at the same intervals and are connected to each other in the same longitudinal position to form a ring-shaped protrusion around the pile body. A grouting pipe is pre-embedded inside the pile body.

[0088] The triangular bamboo-joint pile in this embodiment has an equilateral triangular cross-section, resulting in good geometric symmetry and a relatively balanced force distribution on the three sides, which is beneficial for guiding stability and uniform force distribution during pile driving. The outwardly protruding reinforcing ribs on the three sides are interconnected at the same longitudinal position through the reinforcing rib connecting sections at the chamfer, forming multiple continuous annular protrusions around the pile body, giving the pile a bamboo-joint shape. Compared to the independent reinforcing ribs on the sides in Embodiment 2, the annular protrusions form a complete and continuous annular mechanical interlocking surface at the pile-soil interface, allowing for more efficient utilization of pile side friction and a significant increase in the vertical bearing capacity of a single pile. Simultaneously, the annular protrusions continuously compact the soil around the pile during pile driving, improving the density and mechanical properties of the surrounding soil. Compared to the annular concave reinforcing ribs in Embodiment 4, the outwardly protruding reinforcing ribs have a more direct compaction effect on the soil around the pile during pile driving, but the way the contact area between the pile side and the soil increases differs. Both can be flexibly selected according to actual geological conditions and construction process requirements. After the pile is driven, high-pressure grouting can be injected into the pile bottom and the surrounding soil through the grouting pipe to further improve the pile end bearing capacity and pile side friction, improve the overall stress performance of the pile foundation, and meet the engineering scenarios with high bearing capacity requirements.

[0089] Example 7: A method for preparing an equilateral triangular bamboo-joint pile with annular concave reinforcing ribs.

[0090] This embodiment uses the preparation of the equilateral triangular bamboo-joint pile with annular concave reinforcing ribs described in Embodiment 4 as an example to illustrate the preparation method of the triangular pile with reinforcing ribs of the present invention. This preparation method is also applicable to the triangular piles described in other embodiments.

[0091] See Figure 5 , Figure 5 This is a schematic flowchart of a method for preparing a triangular pile with reinforcing ribs according to an embodiment of the present invention. The preparation method of this embodiment includes the following steps:

[0092] S1. Mold preparation and adjustment.

[0093] The mold body is composed of a bottom mold, two side molds, a top corner mold assembly, two bottom corner mold assemblies, and two front and rear end molds. The top corner mold has a pre-drilled casting hole with the same width (80mm) as the corner mold.

[0094] The inner length of the bottom mold is 12m, and the inner width is 340mm.

[0095] The inner width of the end mold is 340mm.

[0096] Both side molds have an inner length of 12m, an inner width of 340mm, and a wall thickness of 20mm. The lower ends of the two side molds are spliced ​​to the two sides of the bottom mold, and the upper ends of the two side molds are joined together to form the apex of a triangular mold cavity. A pouring opening with a width of 80mm is reserved between the upper ends of the two side molds, extending longitudinally along the pile body.

[0097] Two bottom corner mold assemblies are installed at the corners where the bottom mold meets the two side molds. These bottom corner mold assemblies are detachable, with an inner forming surface that is arc-shaped with a chord length of 80mm, used to create rounded bottom corners. The bottom corner mold assemblies are fixed to the bottom and side molds with bolts. After installation, their inner forming surfaces are flush with the inner walls of the bottom and side molds, and sealing strips are installed at the joints.

[0098] Side reinforcing ribs are formed on the three sides and installed on the inner sides of the two side molds and the bottom mold, respectively. In this embodiment, the side reinforcing ribs are reinforcing ribs protruding into the mold cavity, with a width of 50mm and a protrusion height of 30mm. The reinforcing ribs on the three sides are at the same longitudinal height. Corner reinforcing ribs are formed at corresponding positions on the bottom corner mold assembly. In this embodiment, the corner reinforcing ribs are corner reinforcing ribs with a width of 50mm and a protrusion height of 30mm, and are aligned and connected to the reinforcing ribs on the adjacent sides.

[0099] The reinforcing ribs are fixed to the mold body with bolts, and the spacing between the reinforcing rib protrusions is 1.0m. Sealing strips are installed at the joints of each module to prevent grout leakage during pouring.

[0100] After the above components are assembled, an equilateral triangular mold cavity with a narrow top and wide bottom cross-section is formed. The front side length of the chamfer corresponding to the mold cavity cross-section is 500mm, the chord length of each of the three chamfers is 80mm, and the remaining length of each of the three sides after chamfering is 340mm. The three side reinforcing ribs and the corner reinforcing ribs together form a complete annular molding cavity. By replacing the bottom corner mold components and reinforcing rib molding structures of different specifications, the chamfer chord length, the spacing between reinforcing ribs, and the depth of concavity and convexity can be adjusted.

[0101] S2. Reinforcing cage processing and placement into the formwork.

[0102] A reinforcing cage matching an equilateral triangular cross-section is tied. The reinforcing cage includes longitudinal main bars and spiral stirrups. Triangular cross-section positioning clamps are installed on the reinforcing cage. The tied reinforcing cage is then hoisted into the mold and fixed inside the mold cavity by the positioning clamps.

[0103] The longitudinal main reinforcement bars are ordinary steel bars or prestressed steel bars; when the longitudinal main reinforcement bars are ordinary steel bars, no prestress is applied, and when the longitudinal main reinforcement bars are prestressed steel bars, prestress is applied; in this embodiment, prestressed steel bars are used.

[0104] In this embodiment, grouting pipes are also pre-embedded in the reinforcing cage, and the grouting pipes are fixed to the reinforcing cage by binding or clamping. Depending on the grouting method, the arrangement of the grouting pipes is as follows:

[0105] When using the pile bottom grouting method, the grouting pipe runs longitudinally through the pile body, extending to the designed position at the pile bottom. The lower end has a grout outlet with a one-way check valve. Before pouring, the outlet is temporarily sealed with an end cap to prevent concrete from clogging the grouting pipe during pouring. After pile driving is completed, high-pressure grouting is injected into the pile bottom and surrounding soil through the grouting pipe.

[0106] When using pile-side grouting, the grouting pipe has a grout outlet near the outer periphery of the pile body, facing the surrounding soil. A ruptureable plug is installed at the grout outlet. During the pouring and pile driving stages, the plug seals the grout outlet to prevent mud or concrete from clogging the channel. After pile driving, when high-pressure grouting is performed, the plug ruptures when the grouting pressure reaches the set value, allowing grout to diffuse from the outlet into the surrounding soil.

[0107] When grouting is required at multiple longitudinal positions on the pile body, multiple grouting pipes are pre-embedded in the pile body, and each grouting pipe has a grout outlet hole located at different longitudinal positions.

[0108] The two grouting methods described above can be used individually or in combination. After the grouting pipe is fixed, the subsequent concrete pouring process can proceed. In this embodiment, the equilateral triangular bamboo-joint pile of Example 4 is prepared by bottom grouting, with one grouting pipe positioned at the center of the pile cross-section.

[0109] In this embodiment, prestressed steel bars are used, so this step also includes prestressing tensioning:

[0110] Tensioning plates are installed at both ends of the mold cavity. Pre-tensioning is applied to the longitudinal main bars in the steel cage to control the tension stress value, and the bars are anchored to the tensioning plates.

[0111] In this embodiment, the tensile stress value is controlled to be 0.70 times the standard value of the tensile strength of prestressed steel bars.

[0112] S3, Concrete preparation.

[0113] Prepare concrete with a strength grade of C60. Concrete includes cement, mineral admixtures, coarse and fine aggregates, and additives.

[0114] In this embodiment, the cement dosage is 400 kg / m³, the mineral admixture is a compound of fly ash and mineral powder, the dosage is 20% of the total amount of cementitious materials, the water-cement ratio is 0.30, the sand ratio is 40%, and the admixture is polycarboxylate high-performance water-reducing agent, the dosage of which is determined according to the slump requirement.

[0115] The slump of the concrete mixture is controlled between 80 and 120 mm to ensure that the concrete can fully fill the corner areas of the mold cavity and the forming groove of the reinforcing ribs.

[0116] S4. Pouring and vibrating to form the shape.

[0117] The prepared concrete is poured into the mold in layers through the pouring port at the top of the mold cavity. The pouring depth of each layer of concrete is controlled within 300mm.

[0118] After each layer is poured, an immersion vibrator is used for compaction. The vibrator is inserted quickly and withdrawn slowly, and inserted vertically into the concrete to a depth of 50–100 mm.

[0119] During vibration, focus on the three corner areas of the mold cavity and the corresponding positions of the reinforcing rib forming structures. Perform secondary vibration at the junction of the corner reinforcing rib forming structures (corner reinforcing rib protrusions) and the side reinforcing rib forming structures (side reinforcing rib protrusions) to ensure that the concrete in the annular forming cavity is dense.

[0120] Vibrate until the concrete no longer settles significantly, the surface becomes smooth and no large number of air bubbles escape.

[0121] Vibration of the upper layer of concrete must be completed before the initial setting of the lower layer of concrete.

[0122] Before the top concrete has initially set, the top corner mold is installed at the corner where the two side molds meet, and the mold is closed. Then, pouring continues through the pouring hole of the top corner mold to complete the final shaping of the top corner mold.

[0123] S5, Steam curing.

[0124] The completed pile body is subjected to zoned temperature-controlled steam curing. The zoned temperature-controlled steam curing system sets up independent temperature control zones for the corner areas and the middle areas of the triangular cross-section. Specifically, a first temperature sensor is embedded on the outer side of the three corners of the mold cavity, and a second temperature sensor is embedded on the outer side of the middle of the three sides to monitor the temperature of each zone in real time.

[0125] In this embodiment, the heating rate of the corner region is controlled within 10℃ / h, and the heating rate of the edge-middle region is controlled within 15℃ / h. The constant temperature of the corner region is controlled at 60℃, and the constant temperature of the edge-middle region is controlled at 70℃. The constant temperature time for both is 8 hours. The cooling rate for both is controlled within 10℃ / h. When the measured temperature difference between the corner region and the edge-middle region exceeds 15℃, the heating power of the edge-middle region is automatically reduced to reduce the temperature difference.

[0126] By using different heating rates and constant temperatures in the corner and middle areas, the temperature changes in different parts of the irregular cross-section tend to be consistent, reducing temperature stress and preventing corner cracking.

[0127] S6. Demolding and shipping.

[0128] First, remove the two bottom corner mold components to create space for demolding at the corners with the annular protrusions. Then separate the two side molds, and finally remove the pile from the bottom mold.

[0129] The pile body undergoes quality inspection according to standards, including checking appearance quality, cross-sectional dimensions, location of reinforcing ribs, and patency of grouting pipes. Pile bodies are released from the factory only after passing inspection.

[0130] Since this embodiment uses prestressed steel bars, this step also includes releasing the prestress before demolding, as detailed below:

[0131] After curing, once the concrete strength reaches more than 75% of the design strength, the prestressing is released. After the prestressing is released, the formwork is demolded.

[0132] The preparation method of this embodiment, through the combination of adjustable molds, detachable corner mold components, and reinforcing rib forming modules, enables the production of triangular piles with different cross-sectional specifications, different chamfering forms, and different reinforcing rib spacing and protrusion heights using a single mold. The mold has strong adaptability and high production efficiency. Simultaneously, through layered casting, focused vibration, zoned temperature-controlled curing, and the application and release control of pre-tensioning, the compactness, structural strength, and appearance quality of the triangular irregular cross-section piles are ensured, resulting in a high product qualification rate.

[0133] Comparative Example 1

[0134] This comparative example provides an equilateral triangular pile, whose structure, size and manufacturing process are basically the same as those in Example 4. The only difference is that the steam curing stage does not use zoned temperature control, but instead uses a uniform temperature regime for the entire pile body.

[0135] The test results show that the corner crack occurrence rate of equilateral triangular piles using uniform temperature control curing is about 15% to 20%; while the corner crack occurrence rate of equilateral triangular piles using zoned temperature control curing in Example 4 is reduced to below 2%. This indicates that zoned temperature control curing can effectively reduce the risk of corner cracking of irregular cross-section piles and improve the product qualification rate.

[0136] The detection method for the aforementioned corner crack occurrence rate is as follows: After curing and demolding, each equilateral triangular pile in the same batch undergoes a visual inspection, with a focus on the three corner areas. A crack width gauge is used to measure the crack width, and a crack width greater than 0.1 mm is considered a crack. The corner crack occurrence rate is calculated as the ratio of the number of piles with corner cracks to the total number of piles inspected.

[0137] Comparative Example 2

[0138] This comparative example provides an equilateral triangular pile, whose cross-sectional shape, chamfer form, and grouting pipe arrangement are the same as those in Example 4. The only difference is that no concave reinforcing ribs are provided on the side of the pile body, that is, the outer circumference of the pile body is a smooth surface.

[0139] The test results show that, under the same geological conditions, the vertical bearing capacity of the triangular pile in this comparative example is reduced by about 20% to 35% after pile driving compared with Example 4. This indicates that the reinforcing ribs can effectively increase the contact area between the pile body and the soil, improve the pile side friction, and make a significant contribution to the bearing capacity of the pile foundation.

[0140] The above-mentioned method for testing the vertical bearing capacity of a single pile is as follows: Under the same geological conditions, a single pile vertical static load test is conducted on triangular piles without reinforcing ribs and triangular piles with reinforcing ribs, respectively. Vertical loads are applied in stages and the settlement at the pile top is observed. The ultimate vertical bearing capacity of the single pile is determined based on the load-settlement curve and compared with it.

[0141] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A triangular pile with reinforcing ribs, characterized in that, include: The triangular pile is a solid precast concrete pile, and the cross-section of the triangular pile is a triangular section. The three corners of the triangular cross-section are all chamfered, forming a top chamfer and two bottom chamfers respectively; wherein, the width of the top chamfer is less than the width of the remaining part of the bottom edge after the two bottom chamfers, so that the triangular pile cross-section forms a guide section that is narrow at the top and wide at the bottom; On at least one side of the triangular pile, concave or convex reinforcing ribs are provided at intervals along the longitudinal direction of the pile body; wherein, the concave or convex direction of the reinforcing ribs is perpendicular to the side on which they are located. At least one grouting pipe is pre-embedded inside the triangular pile body, and the grouting pipe extends longitudinally along the pile body and penetrates the triangular pile body.

2. The triangular pile with reinforcing ribs according to claim 1, characterized in that, The triangle is an equilateral triangle or an isosceles triangle.

3. The triangular pile with reinforcing ribs according to claim 1, characterized in that, The chamfer is either a rounded corner or a beveled corner.

4. The triangular pile with reinforcing ribs according to claim 1, characterized in that, The spacing between two adjacent reinforcing ribs on the same side is 0.5 meters to 1.5 meters; when all three sides are provided with reinforcing ribs and the spacing is the same, the reinforcing ribs on the three sides located in the same longitudinal position are connected to each other by the reinforcing ribs set at the chamfer, forming a triangular bamboo joint pile.

5. The triangular pile with reinforcing ribs according to claim 1, characterized in that, The grouting pipe has at least one of the following two structures: The lower end of the grouting pipe extends to the bottom of the pile and is provided with a grout outlet, which is used to inject high-pressure grout into the bottom of the pile and the surrounding soil through the grout outlet after the pile body is driven into the pile. The slurry outlet has a one-way check valve structure; The grouting pipe has at least one grout outlet hole near the outer periphery of the pile body. The grout outlet hole is equipped with a ruptureable sealing element, which is used to rupture and inject grout into the soil around the pile when the grouting pressure reaches a set value.

6. A method for preparing a triangular pile with reinforcing ribs, used to prepare a triangular pile with reinforcing ribs as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation and adjustment of molds: Provide adjustable molds for triangular piles, and select and install the appropriate specifications of corner mold components according to the target pile type; The adjustable mold includes a mold body, and the mold body has a mold cavity with a triangular cross-section. The top width of the mold cavity is smaller than the bottom width, so that the cross-section of the formed pile body forms a guide section that is narrow at the top and wide at the bottom. The mold body has detachable corner mold components at three corners for forming chamfers of different curvatures, angles or lengths; At least one inner side of the mold body is equipped with a detachable side reinforcing rib forming structure. The side reinforcing rib forming structure is provided with reinforcing rib protrusions protruding into the mold cavity or reinforcing rib grooves recessed into the mold cavity. By replacing reinforcing rib forming structures of different specifications, the spacing and / or depth of the reinforcing ribs can be adjusted. The corner mold assembly is equipped with a detachable corner reinforcing rib forming structure, which is either a corner reinforcing rib protrusion or a corner reinforcing rib groove. When the corner reinforcing rib forming structure is installed, the side reinforcing rib forming structures of the corner reinforcing rib forming structure are aligned and connected, so that the pile body forms an annular reinforcing rib around the pile body. When the corner reinforcing rib forming structure is removed, the annular reinforcing rib is broken at the corner, so that the pile body forms an independent reinforcing rib only on the side, and the chamfer remains smooth. S2. Reinforcing cage processing and placement: Bind a reinforcing cage that matches the triangular cross-section. The reinforcing cage includes longitudinal main bars and spiral stirrups. Pre-embed grouting pipes on the reinforcing cage and install triangular cross-section positioning clamps. Hoist the bound reinforcing cage into the mold and fix it in the mold cavity using the positioning clamps. S3. Concrete mix design: Prepare concrete with a strength grade of not less than C40, wherein the concrete includes cement, mineral admixtures, coarse and fine aggregates and additives; S4. Pouring and Vibrating: The prepared concrete is poured into the mold cavity in layers from the top narrow side. Each layer is vibrated with an immersion vibrator. During vibration, the three corner areas of the mold cavity and the corresponding positions of the reinforcing ribs are vibrated. The connection between the corner reinforcing ribs and the side reinforcing ribs is vibrated a second time. The vibrator needs to penetrate into the lower layer of concrete until the concrete fills the mold cavity and is compacted. S5. Steam curing: The cast-in-place pile body is subjected to zoned temperature-controlled steam curing. The zoned temperature-controlled steam curing system sets up independent temperature control zones for the corner area and the middle area of ​​the triangular cross-section. Different heating rates and constant temperatures are used for curing the corner area and the middle area. The heating rate of the corner area is lower than that of the middle area, and the constant temperature of the corner area is lower than that of the middle area. S6. Demolding and Shipment: After curing, first remove the corner mold components, then separate the side molds, demold, and inspect the pile body according to the standards. Only after passing the inspection will the pile be shipped out of the factory.

7. The method for preparing a triangular pile with reinforcing ribs according to claim 6, characterized in that, In step S2, the grouting pipe is fixed to the reinforcing cage by binding or clamping; when pile bottom grouting is used, the lower end of the grouting pipe extends to the pile bottom and is provided with a grout outlet; when pile side grouting is used, the grouting pipe wall is provided with a grout outlet hole, and a ruptureable sealing device is provided at the grout outlet hole.

8. The method for preparing a triangular pile with reinforcing ribs according to claim 6, characterized in that, Between steps S2 and S3, tensioning plates are installed at both ends of the mold cavity to apply pre-tensioning prestress to the longitudinal main bars in the steel cage to control the tensioning stress value and anchor them to the tensioning plates; in step S6, after curing and before demolding, the prestress is released first.

9. The method for preparing a triangular pile with reinforcing ribs according to claim 8, characterized in that, The release of prestressing is carried out after the concrete strength reaches more than 75% of the design strength.

10. The method for preparing a triangular pile with reinforcing ribs according to claim 6, characterized in that, In step S4, the pouring depth of each layer of concrete is controlled within 300mm. The vibrator is inserted quickly and pulled out slowly and inserted vertically into the concrete to a depth of 50-100mm. Vibration is stopped when the concrete no longer sinks significantly, the surface is covered with slurry, and no large number of air bubbles escape. Vibration of the upper layer of concrete must be completed before the initial setting of the lower layer of concrete.

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