Height-adjustable U-shaped channel mold and preparation method of special molding material

Abstract

The invention relates to the technical field of precast concrete component production, in particular to a height-adjustable U-shaped channel mold and a preparation method of a special molding material. A first end mold assembly and a second end mold assembly are arranged on the stable bottom frame in parallel in the U-shaped channel forming direction, and a side mold assembly and an inner mold assembly are arranged between the first end mold assembly and the second end mold assembly and surround each other to form a U-shaped channel forming cavity. A replacement panel is arranged on the inner side wall of the side mold assembly in the height direction, and a plurality of height adjusting blocks are laid at the bottom of a forming cavity between the inner mold assembly and the side mold assembly and used for achieving production of U-shaped channels of different height specifications. The bottoms of the first end mold assembly, the second end mold assembly and the side mold assembly are each provided with a plurality of rotating shaft assemblies and rotationally connected with the stable bottom frame. A pull rod assembly is arranged between the first end mold assembly and the second end mold assembly. According to the invention, flexible height adjustment of the U-shaped channel mold and accurate preparation and maintenance of the forming material are realized, and the requirements of diversified projects on the specification and performance of the U-shaped channel are met.

Description

Technical Field

[0001] This invention relates to the field of precast concrete component production technology, and in particular to a height-adjustable U-shaped channel mold and a method for preparing special molding materials. Background Technology

[0002] In the current precast concrete U-shaped channel production process, traditional technical solutions have several limitations that urgently need to be addressed: First, the height of traditional U-shaped channel molds is fixed. If U-shaped channel products of different heights need to be produced, the entire set of molds must be replaced, which not only significantly increases equipment procurement and storage costs but also prolongs production time, resulting in low production efficiency and difficulty in adapting to diverse specification requirements in engineering projects. Second, the splicing of various components of the mold mostly relies on simple bolt connections, lacking precise positioning structures. This makes it prone to misalignment and grout leakage due to assembly errors, affecting the flatness of the U-shaped channel's appearance and weakening its structural integrity, increasing potential problems in later engineering projects. Third, during the demolding process, the disassembly of the mold's enclosing structure is cumbersome and often requires external force to forcibly dismantle it. Fourth, concrete is prone to cracking due to volume shrinkage after pouring, and traditional curing methods rely heavily on the natural environment, making it difficult to precisely control temperature and humidity, which can lead to uneven curing. This makes it difficult for key performance indicators such as 28-day compressive strength and impermeability grade of the U-shaped channel to consistently meet standards, affecting the service life of the project. Fifth, in the preparation of traditional concrete materials, fiber-reinforcing materials are prone to agglomeration and uneven mixing of dry materials, which further affects the overall performance of the concrete and fails to fully utilize the role of reinforcing materials. Therefore, developing a U-shaped channel mold with adjustable height, convenient demolding, and effective prevention of concrete shrinkage cracks, as well as a method for preparing its molding materials, is of great practical significance. Summary of the Invention

[0003] To address some of the problems existing in the prior art, this invention provides a height-adjustable U-shaped channel mold. This mold enables flexible adjustment of the height of the U-shaped channel forming cavity, meeting the production needs of U-shaped channels of different heights and specifications. It significantly improves the versatility and utilization rate of the mold and is widely used in water conservancy projects such as farmland irrigation and urban drainage.

[0004] To achieve the above objectives, the present invention provides a height-adjustable U-shaped channel mold, including a stable base frame for supporting the overall structure; a first end mold assembly and a second end mold assembly are arranged parallel to each other along the U-shaped channel forming direction on the stable base frame, and a side mold assembly and an inner mold assembly are arranged between the first end mold assembly and the second end mold assembly, which together form a U-shaped channel forming cavity; positioning pin assemblies are fitted on the first end mold assembly and the second end mold assembly and are respectively connected to the side mold assembly for clearance fit at the mold splicing point to avoid misalignment and slurry leakage; a replaceable insert is provided on the inner side wall of the side mold assembly along the height direction, the replaceable insert can be disassembled and replaced individually, and a sealing strip is embedded at the splicing seam; the bottom of the forming cavity between the inner mold assembly and the side mold assembly is laid with There are multiple height adjustment blocks with various thicknesses, used for stepped height adjustment to achieve U-shaped channel production of different height specifications; the uppermost height adjustment block is also equipped with a floating forming strip to compensate for the volume shrinkage after concrete pouring in real time and avoid shrinkage cracks; the bottom of the first end mold assembly, the second end mold assembly, and the side mold assembly are all equipped with multiple sets of rotating shaft assemblies, which are rotatably connected to the stable base frame through the rotating shaft assemblies, with a rotation angle of 0° to 90°, for quickly releasing the enclosure support to assist demolding; the outer walls of the first end mold assembly, the second end mold assembly, and the side mold assembly are all equipped with flap support assemblies, and a tie rod assembly is also provided between the first end mold assembly and the second end mold assembly for adjusting the tightness of the connection with the side mold assembly.

[0005] One beneficial effect of this invention is that: the stable base provides a solid bearing foundation for the overall structure, while the positioning pin assembly between the first and second end mold components enables precise splicing, effectively avoiding misalignment and grout leakage at the mold splicing points, thus ensuring the quality of the U-shaped channel forming; the detachable replaceable inserts on the inner wall of the side mold components and the height adjustment blocks of various thicknesses between the inner and side mold components allow for the production of U-shaped channels of different heights without replacing the entire set of molds, significantly reducing equipment investment and specification switching costs; the floating forming strip on the uppermost height adjustment block can compensate for the volume shrinkage after concrete pouring in real time, effectively preventing shrinkage cracks; the bottom of the first, second, and side mold components is rotatably connected to the stable base via a rotating shaft assembly, and with the flap support assembly on the outer wall and the tie rod assembly between the components, the tightness of the connection between each component can be flexibly adjusted to ensure the stability of the enclosure, while also enabling rapid rotation and demolding, avoiding damage to the blank during demolding, significantly improving production efficiency and yield; at the same time, the structural design of each component takes into account both disassembly and stability, facilitating later maintenance and component replacement, and extending the overall service life of the mold.

[0006] As a further improvement of the present invention, in order to enhance the structural strength of the first end mold assembly, optimize its compatibility with other components, and improve assembly stability, the first end mold assembly includes a first end plate body, and a plurality of first connecting partitions are arranged in parallel on the outer end face of the first end plate body; an insertion forming plate is provided on the inner end face of the first end plate body, and screw fasteners are fitted on the insertion forming plate and detachably connected to the inner end face of the first end plate body through the screw fasteners; steel pipes are also symmetrically arranged on both sides of the first end plate body, and a locking block is welded to the outer end of the steel pipe.

[0007] As a further improvement of the present invention, in order to enhance the structural strength of the second end mold assembly, optimize its connection compatibility with other components, and improve assembly accuracy and stability, the second end mold assembly includes a second end plate body, and a plurality of second connecting partitions are arranged parallel to each other on the outer end surface of the second end plate body; a socket forming plate is provided on the inner end surface of the second end plate body, and a plurality of mounting positioning holes are evenly spaced on the socket forming plate; connecting blocks are also symmetrically arranged on both sides of the second end plate body, and an arc-shaped plate is welded to the outer end of the connecting block.

[0008] As a further improvement of the present invention, in order to significantly enhance the deformation resistance of the side mold assembly and ensure the appearance and structural accuracy of the U-shaped channel after molding, the side mold assembly includes a symmetrically arranged side mold body. Multiple molding blocks are spaced apart on the inner sidewall of the side mold body and located at the upper end of the replaceable panel. Multiple nuts and fasteners are fitted onto the replaceable panel and are detachably connected to the side mold body via these fasteners. A molding circular module is also provided between the molding blocks. A bending plate is provided on the upper outer side of the side mold body, with a bending angle of 90°. A reinforcing rib is provided on the lower outer side of the side mold body, with several reinforcing ribs evenly spaced apart.

[0009] As a further improvement of the present invention, in order to provide a stable load-bearing foundation, while ensuring compatibility with other supporting components, improving service life, and avoiding structural failure due to poor welding or easy rusting, the stable base frame includes parallel second channel steels, with first channel steels welded perpendicularly between the second channel steels; a third channel steel is welded along the length of the first channel steel, the width of the third channel steel corresponding to the bottom width of the inner mold component, and a plurality of slots are evenly spaced on it; the welds between the first channel steel, the second channel steel, and the third channel steel are full welds, and rust prevention treatment is performed after welding.

[0010] As a further improvement of the present invention, in order to provide vertical support force, assist in mold stability, and facilitate operation and improve ease of use, the flip plate support assembly includes a support plate, a flip plate, a handle, and bolt and nut connectors; one end of the support plate is fixedly connected to the outer side wall of the first end mold assembly, the second end mold assembly, and the side mold assembly, and the other end of the support plate is rotatably connected to one end of the flip plate through bolt and nut connectors, with a rotation angle of 0° to 180°; a handle is provided at the free end of the flip plate, and the outer surface of the handle is covered with an anti-slip rubber sleeve; the handle is turned and drives the flip plate to rotate, so that the top of the free end of the flip plate abuts against the stable base frame, providing vertical support force.

[0011] As a further improvement of the present invention, in order to ensure the stability of the shaft assembly connection, reduce the wear between the shaft and the copper sleeve, and facilitate maintenance, the shaft assembly includes a shaft, and a copper sleeve is fitted on the outer side of the shaft; a straight-through oil injection cup is provided at one end of the shaft, and the oil outlet of the straight-through oil injection cup is connected to the internal oil passage of the shaft for injecting lubricating oil into the mating surface between the shaft and the copper sleeve to reduce wear; tilting plates are provided on both sides of the copper sleeve on the shaft, and fixing plates are symmetrically fitted on the outer side of the copper sleeve; the fixing plates are welded and fixed to the stabilizing base, and the tilting plates are respectively fixedly connected to the bottom of the first end mold assembly, the second end mold assembly and the side mold assembly; an annular groove is provided at the other end of the shaft, and a shaft elastic retaining ring is fitted in the annular groove to limit the axial displacement of the shaft during operation.

[0012] As a further improvement of the present invention, in order to flexibly adjust the tightness of the connection of each component and ensure the stability of the mold enclosure; at the same time, to achieve rapid demolding and avoid damage to the blank during demolding, significantly improving production efficiency and yield; the pull rod assembly includes a connecting pull rod, a flip claw, and a connecting pin; one end of the connecting pull rod is equipped with a flange nut fastener, and the other end is provided with a pull plate; the connecting pin is provided on the pull plate, and the flip claw is rotatably connected to the pull plate through the connecting pin; the connecting pull rod abuts against the second end mold assembly through the flange nut fastener, and the connecting pull rod is clamped onto the first end mold assembly through the pull plate and the flip claw; a pressure rod is also connected to the flip claw, and when the pressure rod is moved, it drives the flip claw to rotate, thereby achieving clamping or loosening with the first end mold assembly.

[0013] This invention also provides a method for preparing special materials for U-shaped channel forming. This method has a standardized process, is highly operable, suitable for large-scale production, and can stably output high-performance U-shaped channel products, meeting the requirements for component strength and durability. The method includes the following steps:

[0014] Step 1: Raw material pretreatment and precise batching. Silicate cement is selected and sieved through an 80-mesh screen before use to remove agglomerated particles. Continuously graded granite crushed stone with a particle size of 5–20 mm, a mud content ≤1%, and a needle-like / flaky particle content ≤5% is selected; it is rinsed with clean water until the surface is free of dust and then dried to a moisture content ≤1%. Medium sand with a fineness modulus of 2.3–3.0, a mud content ≤3%, and a mud lump content ≤1% is selected; it is dried to a moisture content of 3–5%. Pure tap water with a pH of 6.5–7.5 is used. Basalt fiber is selected and pretreated with 0.5% polyvinyl alcohol dispersant for 10–15 minutes to prevent clumping. High-activity silica fume with a silica content ≥90% is selected; it is stored in a sealed container and allowed to return to room temperature before use. Polycarboxylate superplasticizer with a water reduction rate ≥25% is selected and diluted before use.

[0015] Step Two: Staged Mixing and Stirring. In the dry mixing stage, add the weighed cement, continuously graded crushed stone, medium sand, and silica fume to an external forced mixer. Set the mixing speed to 180–200 rpm and dry mix for 1–2 minutes until the mixture is uniform in color and shows no obvious particle stratification. In the fiber dispersion stage, maintain the constant speed and slowly add basalt fibers, continuing to mix for 30–60 seconds. The high-speed shearing of the mixer ensures the fibers are evenly dispersed without agglomeration. In the wet mixing stage, mix water and polycarboxylate superplasticizer evenly and slowly inject into the mixer. Adjust the speed to 220–240 rpm and wet mix for 2–3 minutes. During this period, stop the machine 2–3 times to observe and break up any localized dry clumps. After mixing, check the slump of the concrete mixture, controlling it to 50–80 mm. If it does not meet the standard, adjust the water amount until it does.

[0016] Step 3: Mold Preparation and Casting. First, clean the mold by blowing away dust and debris from the molding cavity with compressed air at 0.6–0.8 MPa. Then, evenly apply a water-based release agent to the side mold components, inner mold components, replacement panels, and floating molding strips. Let it stand for 5–10 minutes until the release agent forms a film. Next, cast the mixture in two stages. For the first stage, cast to half the height of the molding cavity and vibrate with a high-frequency vibrator for 30–40 seconds, keeping the vibrator 5–10 mm away from the mold to avoid collisions. After vibration, cast the mixture a second time until it is flush with the top of the mold and vibrate again for 20–30 seconds until no air bubbles overflow from the surface of the mixture and the slurry is evenly distributed. During the casting process, promptly clean up any mixture that overflows from the mold to prevent it from solidifying and affecting demolding.

[0017] Step 4: Multi-stage curing treatment. The pre-curing stage involves covering the top of the mold with plastic film after pouring, placing the mold and the U-shaped channel blank in a curing chamber at a temperature of 20-25℃ and relative humidity ≥90% for 2-4 hours to allow the concrete to initially set and prevent excessive evaporation of surface moisture. The steam curing stage involves removing the plastic film after pre-curing, transferring the mold and blank into the steam curing chamber, closing the chamber door, and starting the steam generator to raise the temperature to 45-55℃ at a rate of 5-10℃ / h. The temperature is recorded every 30 minutes to ensure uniform heating. Once the set temperature is reached, maintain constant temperature curing for 6-8 hours, with relative humidity ≥95% during this period, and continuously replenish steam through the steam generator. After the constant temperature period, increase the steam rate by 3-5℃ / h. The cooling rate should be adjusted to bring the temperature down to room temperature. Rapid cooling is strictly prohibited during the cooling process to avoid temperature cracks in the concrete. The natural curing stage involves opening the steam curing chamber door after steam curing and allowing it to stand for 1-2 hours. Then, the mold is removed. First, the tie rod assembly is loosened, then the flip-plate support assembly is flipped over, and finally, the first end mold assembly, the second end mold assembly, and the side mold assembly are opened through the rotating shaft assembly. The demolded U-shaped channel is then transferred to the natural curing area. During this period, the surface is covered with burlap sacks or geotextile and watered 3-4 times a day to keep the product surface moist. Natural curing takes 7-14 days. During the curing period, the ambient temperature must be ≥5℃. If the ambient temperature is <5℃, rock wool blankets must be used for insulation. After curing, the 28-day compressive strength of the U-shaped channel is tested to be ≥C30 and the impermeability grade is ≥P6. If the requirements are met, it is considered a qualified finished product.

[0018] Another beneficial effect of this invention is that: precise pretreatment of raw materials ensures their purity and performance stability, laying the foundation for the overall performance of concrete; the staged mixing process controls the dry mixing speed and time to achieve uniform mixing of dry materials, maintains the speed to add fibers to ensure uniform dispersion, adjusts the speed for wet mixing and tests the slump, effectively ensuring the uniformity and fluidity of the concrete mixture and meeting molding requirements; in the mold preparation stage, compressed air cleaning and water-based release agent application ensure a clean molding environment, and two-stage pouring combined with high-frequency vibration ensures concrete density and avoids internal air bubbles; multi-stage curing treatment prevents excessive evaporation of moisture from the concrete surface through pre-curing, steam curing precisely controls the heating and cooling rate and temperature and humidity to promote strength development, and natural curing ensures stable strength in the later stage, effectively avoiding temperature cracks and shrinkage cracks. At the same time, the demolding steps and temperature control requirements for the curing environment are clearly defined to ensure that the U-shaped channel meets the specifications and standards, resulting in a high finished product qualification rate.

[0019] In operation, this invention first constructs a height-adjustable U-shaped channel mold, with a stable base supporting the entire structure. A first end mold assembly and a second end mold assembly are arranged parallel to each other along the U-shaped channel forming direction on the stable base. A side mold assembly and an inner mold assembly are positioned between the first and second end mold assemblies, forming a U-shaped channel forming cavity. Positioning pins on the first and second end mold assemblies are connected to the side mold assemblies to achieve a gap fit at the mold joints, preventing misalignment and slurry leakage. Replaceable inserts, which can be individually removed and replaced along the height direction, are installed on the inner wall of the side mold assemblies, with sealing strips embedded at the joints. Height-adjustable blocks of various thicknesses are laid at the bottom of the forming cavity between the inner mold assembly and the side mold assemblies to achieve stepped height adjustment. To meet the production needs of U-shaped channels of different heights and specifications, floating forming strips are installed on the uppermost height adjustment block to compensate for the volume shrinkage of concrete after pouring and avoid shrinkage cracks. Simultaneously, multiple sets of rotating shaft assemblies are installed at the bottom of the first end mold assembly, the second end mold assembly, and the side mold assembly, which are connected to the stable base frame by rotation from 0° to 90° to quickly release the enclosure support and assist in demolding. Flip plate support assemblies are installed on the outer walls of all three. Tie rod assemblies are installed between the first and second end mold assemblies to adjust the tightness of the connection with the side mold assembly. Next, the special materials for U-shaped channel forming are prepared. First, raw material pretreatment and precise batching are carried out, using silicate cement and granules that have been sieved through an 80-mesh screen to remove lumps before use. The following materials are used: continuously graded granite crushed stone with a diameter of 5-20mm, a mud content of ≤1%, a needle-like particle content of ≤5%, washed with clean water until the surface is free of floating dust and then dried to a moisture content of ≤1%; medium sand with a fineness modulus of 2.3-3.0, a mud content of ≤3%, a mud lump content of ≤1%, and dried to a moisture content of 3-5%; pure tap water with a pH of 6.5-7.5; basalt fibers pretreated with 0.5% polyvinyl alcohol dispersant for 10-15 minutes to prevent agglomeration; high-activity silica fume with a silica content of ≥90% and stored in a sealed container and restored to room temperature before use; and polycarboxylate superplasticizer with a water reduction rate of ≥25% and diluted before use. The mixture is then stirred in stages. In the dry mixing stage, the weighed cement, continuously graded crushed stone, medium sand, and silica fume are added. The external forced mixer is used, and the mixing speed is set to 180-200 r / min for dry mixing for 1-2 minutes until the mixture is uniform in color and there is no obvious particle stratification. During the fiber dispersion stage, the basalt fiber is slowly added while maintaining the constant speed, and mixing is continued for 30-60 seconds. The high-speed shearing of the mixer ensures that the fiber is evenly dispersed without agglomeration. During the wet mixing stage, water and polycarboxylate superplasticizer are mixed evenly and then slowly injected into the mixer. The speed is adjusted to 220-240 r / min, and wet mixing is carried out for 2-3 minutes. During this period, the machine is stopped 2-3 times to observe and break up any local dry material clumps. After mixing, the slump of the concrete mixture is tested and controlled to be 50-80 mm. If it does not meet the standard, the water volume is adjusted until it does. Then, the mold is prepared and the concrete is poured and formed. Initially, 0.6-0.8MPa compressed air is used to blow away dust and debris from the molding cavity to clean the mold. Next, a water-based release agent is evenly applied to the side mold assembly, inner mold assembly, replacement inserts, and floating molding strip surfaces, and allowed to stand for 5-10 minutes until the release agent forms a film. Then, the mold is poured in two stages. The first pour reaches half the height of the molding cavity, and a high-frequency vibrator is used to compact it for 30-40 seconds, maintaining a 5-10mm distance between the vibrator and the mold to avoid collision. After compaction, the second pour is made until it is flush with the top of the mold, and then vibrated again for 20-30 seconds until no air bubbles remain on the surface of the mixture. The overflow and slurry should be evenly distributed. During the pouring process, any overflowing mixture from the mold should be cleaned promptly to prevent it from affecting demolding after solidification. Finally, a multi-stage curing treatment should be carried out. In the pre-curing stage, after pouring, the top of the mold should be covered with plastic film, and the mold and U-shaped channel blank should be placed in a curing room with a temperature of 20-25℃ and a relative humidity of ≥90% for 2-4 hours to allow the concrete to initially set and prevent excessive evaporation of surface moisture. After pre-curing, the plastic film should be removed, and the mold and blank should be transferred to a steam curing room. The curing room door should be closed, and the steam generator should be started at 5-10℃. The temperature in the curing chamber is raised to 45-55℃ at a heating rate of h, with the temperature recorded every 30 minutes to ensure uniform heating. Once the set temperature is reached, it is maintained at a constant temperature for 6-8 hours, with the relative humidity in the curing chamber ≥95% during this period, and steam is continuously supplied via a steam generator. After the constant temperature period, the temperature is lowered to room temperature at a rate of 3-5℃ / h, and rapid cooling is strictly prohibited during the cooling process to avoid temperature cracks in the concrete. After steam curing is completed, the door of the steam curing chamber is opened and the chamber is left to stand for 1-2 hours before removing the mold. First, the tie rod assembly is loosened. Next, flip the flap support assembly, and finally open the enclosed first end mold assembly, second end mold assembly, and side mold assembly through the rotating shaft assembly. Transfer the demolded U-shaped channel to the natural curing area. During this period, cover its surface with burlap sacks or geotextile, and sprinkle water 3-4 times daily to keep the product surface moist. Allow it to cure naturally for 7-14 days. Ensure the ambient temperature is ≥5℃ during curing. If the ambient temperature is <5℃, cover with rock wool blankets for insulation. After curing, test the U-shaped channel's 28-day compressive strength to be ≥C30 and its impermeability grade to be ≥P6. If these requirements are met, it is considered a qualified finished product. Attached Figure Description

[0020] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings:

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 This is the front view of the present invention.

[0023] Figure 3 This is a left-side view of the present invention.

[0024] Figure 4 For the present invention Figure 2Schematic diagram of the cross section at point AA.

[0025] Figure 5 This is a schematic diagram of the structure of the first end module assembly in this invention. Figure 1 .

[0026] Figure 6 This is a schematic diagram of the structure of the first end module assembly in this invention. Figure 2 .

[0027] Figure 7 This is a schematic diagram of the structure of the second end module assembly in this invention. Figure 1 .

[0028] Figure 8 This is a schematic diagram of the structure of the second end module assembly in this invention. Figure 2 .

[0029] Figure 9 This is a schematic diagram of the side mold assembly in the present invention. Figure 1 .

[0030] Figure 10 This is a schematic diagram of the side mold assembly in the present invention. Figure 2 .

[0031] Figure 11 This is a schematic diagram of the side mold assembly in this invention.

[0032] Figure 12 This is a schematic diagram of the flap support assembly in this invention. Figure 1 .

[0033] Figure 13 This is a schematic diagram of the flap support assembly in this invention. Figure 2 .

[0034] Figure 14 This is a schematic diagram of the rotating shaft assembly in this invention.

[0035] Figure 15 This is a schematic diagram of the tie rod assembly in this invention.

[0036] Figure 16 This is a schematic diagram of the finished product molding material preparation process in this invention.

[0037] Among them, 1 is the first end mold assembly, 101 is the socket forming plate, 102 is the first end plate body, 103 is the first connecting partition, 104 is the screw fastener, 105 is the steel pipe, 106 is the clamping block; 2 is the second end mold assembly, 201 is the socket forming plate, 202 is the second end plate body, 203 is the second connecting partition, 204 is the connecting block, 205 is the arc plate, 206 is the mounting positioning hole, 3 is the positioning pin assembly; 4 is the side mold assembly, 401 is the side template body, 402 is the forming mold block, 403 is the forming round module, 404 is the bending plate, 405 is the nut fastener, 406 is the reinforcing rib plate, 5 is the inner mold assembly, and 6 is the stabilizing base. Frame, 601 First channel steel, 602 Second channel steel, 603 Third channel steel, 604 Slot, 7 Flip plate support assembly, 701 Support plate, 702 Flip plate, 703 Handle, 704 Bolt and nut connector, 8 Shaft assembly, 801 Straight-through pressure injection cup, 802 Shaft, 803 Flip plate, 804 Copper sleeve, 805 Fixing plate, 806 Shaft elastic retaining ring, 9 Tie rod assembly, 901 Flange nut fastener, 902 Connecting tie rod, 903 Tie plate, 904 Flip claw, 905 Connecting pin, 906 Pressure rod, 10 Replacement panel, 11 Floating forming strip, 12 Height adjustment block. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solutions in this application, the following description is provided in conjunction with the appendix. Figure 1-16 The present invention will be further described below. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] like Figure 1-15The illustrated height-adjustable U-shaped channel mold includes a stable base frame 6 for supporting the overall structure. A first end mold assembly 1 and a second end mold assembly 2 are arranged parallel to each other along the U-shaped channel forming direction on the stable base frame 6. A side mold assembly 4 and an inner mold assembly 5 are arranged between the first end mold assembly 1 and the second end mold assembly 2, forming a U-shaped channel forming cavity. Positioning pin assemblies 3 are fitted onto the first end mold assembly 1 and the second end mold assembly 2, and are connected to the side mold assembly 4 respectively, for clearance fitting at the mold joints to prevent misalignment and grout leakage. A replaceable insert 10 is provided on the inner wall of the side mold assembly 4 along the height direction. The replaceable insert 10 can be individually disassembled and replaced, and a tight seal is embedded at the joint. Sealing strips; multiple height adjustment blocks 12 are laid at the bottom of the forming cavity between the inner mold assembly 5 and the side mold assembly 4. The thickness of the height adjustment blocks 12 varies and is used for stepped height adjustment to achieve the production of U-shaped channels of different height specifications; a floating forming strip 11 is also provided on the uppermost height adjustment block 12 to compensate for the volume shrinkage after concrete pouring in real time and avoid shrinkage cracks; multiple sets of rotating shaft assemblies 8 are provided at the bottom of the first end mold assembly 1, the second end mold assembly 2 and the side mold assembly 4, and are rotatably connected to the stable base frame 6 through the rotating shaft assembly 8. The rotation angle is 0° to 90°, which is used to quickly release the enclosure support to assist demolding; the first end mold assembly 1, the second end mold assembly 2 and the side mold assembly 4 are all provided with multiple sets of rotating shaft assemblies 8. A flap support assembly 7 is installed on the outer side wall of component 4. A tie rod assembly 9 is also provided between the first end mold assembly 1 and the second end mold assembly 2 for adjusting the tightness of the connection with the side mold assembly 4. The first end mold assembly 1 includes a first end plate body 102, and a plurality of first connecting partitions 103 are arranged parallel to each other on the outer end face of the first end plate body 102. An insertion forming plate 101 is provided on the inner end face of the first end plate body 102, and a screw fastener 104 is fitted on the insertion forming plate 101 and detachably connected to the inner end face of the first end plate body 102 through the screw fastener 104. Steel pipes 105 are also symmetrically arranged on both sides of the first end plate body 102. The outer end is welded with a locking block 106; the second end mold assembly 2 includes a second end plate body 202, and a plurality of second connecting partitions 203 are arranged parallel to each other on the outer end face of the second end plate body 202; a socket forming plate 201 is provided on the inner end face of the second end plate body 202, and a plurality of mounting positioning holes 206 are evenly spaced on the socket forming plate 201; connecting blocks 204 are also symmetrically arranged on both sides of the second end plate body 202, and an arc plate 205 is welded to the outer end of the connecting block 204; the side mold assembly 4 includes a symmetrically arranged side template body 401, and a plurality of forming molding blocks 402 are spaced apart on the inner side wall of the side template body 401 and located at the upper end of the replacement insert 10;The replaceable panel 10 is fitted with multiple nuts and fasteners 405, which are detachably connected to the side template body 401. A forming circular module 403 is also provided between the forming molding blocks 402. A bending plate 404 is provided on the upper outer side of the side template body 401, with a bending angle of 90°. A reinforcing rib 406 is provided on the lower outer side of the side template body 401, with several reinforcing ribs 406 evenly spaced. The stabilizing base frame 6 includes parallel second channel steels 602, with a first channel steel 601 vertically welded between the second channel steels 602. A third channel steel 601 is welded along the length of the first channel steel 601. The width of the three channel steels 601 corresponds to the bottom width of the inner mold assembly 5, and several slots 604 are evenly spaced on them; the welds between the first channel steel 601, the second channel steel 602, and the third channel steel 601 are fully welded and rust-proofed after welding; the flip plate support assembly 7 includes a support plate 701, a flip plate 702, a handle 703, and bolt and nut connectors 704; one end of the support plate 701 is fixedly connected to the outer side wall of the first end mold assembly 1, the second end mold assembly 2, and the side mold assembly 4, and the other end of the support plate 701 is rotatably connected to one end of the flip plate 702 through bolt and nut connectors 704, with a rotation angle of 0° to 180°; the free... The shaft assembly 8 is provided with a handle 703, the outer surface of which is covered with an anti-slip rubber sleeve. The handle 703 is turned to rotate the flap 702, causing the top of the free end of the flap 702 to abut against the stable base 6, providing vertical support. The shaft assembly 8 includes a shaft 802, the outer side of which is fitted with a copper sleeve 804. One end of the shaft 802 is provided with a straight-through oil injection cup 801, the oil outlet of which communicates with the internal oil passage of the shaft 802, for injecting lubricating oil into the mating surface between the shaft 802 and the copper sleeve 804 to reduce wear. Tilting plates 803 are provided on both sides of the copper sleeve 804 on the shaft 802, and the outer side of the copper sleeve 804 is also symmetrically fitted with... A fixed plate 805 is provided; the fixed plate 805 is welded and fixed to the stable base frame 6; the tilting plate 803 is fixedly connected to the bottom of the first end mold assembly 1, the second end mold assembly 2 and the side mold assembly 4 respectively; the other end of the rotating shaft 802 is provided with an annular groove, and a shaft elastic retaining ring 806 is inserted in the annular groove to limit the axial displacement of the rotating shaft 802 during operation; the tie rod assembly 9 includes a connecting tie rod 902, a flipping claw 904 and a connecting pin 905; one end of the connecting tie rod 902 is equipped with a flange nut fastener 901, and the other end is provided with a pull plate 903; the connecting pin 905 is provided on the pull plate 903, and the flipping claw 904 is rotatably connected to the pull plate 903 through the connecting pin 905;The connecting rod 902 abuts against the second end mold assembly 2 via a flange nut fastener 901. The connecting rod 902 is also secured to the first end mold assembly 1 via a pull plate 903 and a flipper 904. A pressure rod 906 is also connected to the flipper 904. When the pressure rod 906 is moved, it causes the flipper 904 to rotate, thereby locking or releasing it from the first end mold assembly 1.

[0041] like Figure 1-16 The method for preparing a special material for U-shaped channel forming, as shown, includes the following steps:

[0042] Step 1: Raw material pretreatment and precise batching. Silicate cement is selected and sieved through an 80-mesh screen before use to remove agglomerated particles. Continuously graded granite crushed stone with a particle size of 5–20 mm, a mud content ≤1%, and a needle-like / flaky particle content ≤5% is selected; it is rinsed with clean water until the surface is free of dust and then dried to a moisture content ≤1%. Medium sand with a fineness modulus of 2.3–3.0, a mud content ≤3%, and a mud lump content ≤1% is selected; it is dried to a moisture content of 3–5%. Pure tap water with a pH of 6.5–7.5 is used. Basalt fiber is selected and pretreated with 0.5% polyvinyl alcohol dispersant for 10–15 minutes to prevent clumping. High-activity silica fume with a silica content ≥90% is selected; it is stored in a sealed container and allowed to return to room temperature before use. Polycarboxylate superplasticizer with a water reduction rate ≥25% is selected and diluted before use.

[0043] Step Two: Staged Mixing and Stirring. In the dry mixing stage, add the weighed cement, continuously graded crushed stone, medium sand, and silica fume to an external forced mixer. Set the mixing speed to 180–200 rpm and dry mix for 1–2 minutes until the mixture is uniform in color and shows no obvious particle stratification. In the fiber dispersion stage, maintain the constant speed and slowly add basalt fibers, continuing to mix for 30–60 seconds. The high-speed shearing of the mixer ensures the fibers are evenly dispersed without agglomeration. In the wet mixing stage, mix water and polycarboxylate superplasticizer evenly and slowly inject into the mixer. Adjust the speed to 220–240 rpm and wet mix for 2–3 minutes. During this period, stop the machine 2–3 times to observe and break up any localized dry clumps. After mixing, check the slump of the concrete mixture, controlling it to 50–80 mm. If it does not meet the standard, adjust the water amount until it does.

[0044] Step 3: Mold Preparation and Casting. First, clean the mold by blowing away dust and debris from the molding cavity with compressed air at 0.6–0.8 MPa. Then, evenly apply a water-based release agent to the surfaces of the side mold assembly 4, inner mold assembly 5, replacement panel 10, and floating molding strip 11, and let it stand for 5–10 minutes until the release agent forms a film. Then, cast the mixture in two stages. The first stage involves casting to half the height of the molding cavity and vibrating with a high-frequency vibrator for 30–40 seconds, keeping the vibrator 5–10 mm away from the mold to avoid collisions. After vibration, cast the mixture a second time until it is flush with the top of the mold and vibrate again for 20–30 seconds until no air bubbles overflow from the surface of the mixture and the slurry is uniform. During the casting process, promptly clean up any mixture overflowing from the mold to prevent it from solidifying and affecting demolding.

[0045] Step 4: Multi-stage curing treatment. The pre-curing stage involves covering the top of the mold with plastic film after pouring, placing the mold and the U-shaped channel blank in a curing chamber at a temperature of 20-25℃ and relative humidity ≥90% for 2-4 hours to allow the concrete to initially set and prevent excessive evaporation of surface moisture. The steam curing stage involves removing the plastic film after pre-curing, transferring the mold and blank into the steam curing chamber, closing the chamber door, and starting the steam generator to raise the temperature to 45-55℃ at a rate of 5-10℃ / h. The temperature is recorded every 30 minutes to ensure uniform heating. Once the set temperature is reached, maintain constant temperature curing for 6-8 hours, with relative humidity ≥95% during this period, and continuously replenish steam through the steam generator. After the constant temperature period, cool down at a rate of 3-5℃ / h. The temperature is lowered to room temperature at a rapid rate. Rapid cooling is strictly prohibited during the cooling process to avoid temperature cracks in the concrete. The natural curing stage involves opening the steam curing chamber door after steam curing and allowing it to stand for 1-2 hours. Then, the mold is removed. First, the tie rod assembly 9 is loosened, then the flip-plate support assembly 7 is flipped over, and finally, the first end mold assembly 1, the second end mold assembly 2, and the side mold assembly 4 are opened through the rotating shaft assembly 8. The demolded U-shaped channel is then transferred to the natural curing area. During this period, the surface is covered with burlap sacks or geotextile and watered 3-4 times a day to keep the product surface moist. Natural curing lasts for 7-14 days. During the curing period, the ambient temperature must be ≥5℃. If the ambient temperature is <5℃, rock wool blankets must be used for insulation. After curing, the 28-day compressive strength of the U-shaped channel is tested to be ≥C30 and the impermeability grade is ≥P6. If the requirements are met, it is considered a qualified finished product.

[0046] In operation, this invention first constructs a height-adjustable U-shaped channel mold, supported by a stable base frame 6. A first end mold assembly 1 and a second end mold assembly 2 are arranged parallel to each other along the U-shaped channel forming direction on the stable base frame 6. A side mold assembly 4 and an inner mold assembly 5 are positioned between the first end mold assembly 1 and the second end mold assembly 2, forming a U-shaped channel forming cavity. Positioning pin assemblies 3, fitted on the first and second end mold assemblies 1 and 2 respectively, connect to the side mold assembly 4 to achieve a gap fit at the mold joints, preventing misalignment and grout leakage. Replaceable inserts 10, which can be individually disassembled and replaced along the height direction on the inner wall of the side mold assembly 4, are fitted with sealing strips at the joints. Height-adjustable blocks 12 of various thicknesses are laid at the bottom of the forming cavity between the inner mold assembly 5 and the side mold assembly 4 to achieve stepped height adjustment, meeting the production needs of U-shaped channels of different heights. A floating forming strip 11 is installed on the uppermost height-adjustable block 12 to compensate for volume shrinkage after concrete pouring in real time, preventing product leakage. Shrinkage cracks are generated. Simultaneously, multiple sets of rotating shaft assemblies 8 are installed at the bottom of the first end mold assembly 1, the second end mold assembly 2, and the side mold assembly 4. These rotating shaft assemblies 8 are connected to the stable base frame 6 at a 0°–90° rotation angle to quickly release the enclosure support and assist in demolding. Flip plate support assemblies 7 are installed on the outer walls of all three. A tie rod assembly 9 is installed between the first end mold assembly 1 and the second end mold assembly 2 to adjust the tightness of the connection with the side mold assembly 4. Next, the preparation of special materials for U-shaped channel forming is carried out, starting with… Raw material pretreatment and precise batching: Silicate cement that has been sieved through an 80-mesh screen to remove agglomerated particles before use; continuously graded granite crushed stone with a particle size of 5–20 mm, a mud content ≤1%, and a needle-like / flaky particle content ≤5%, washed with clean water until surface dust-free and dried to a moisture content ≤1%; medium sand with a fineness modulus of 2.3–3.0, a mud content ≤3%, and a clay lump content ≤1%, dried to a moisture content 3–5%; and pure tap water with a pH value of 6.5–7.5.Pre-treating with 5% polyvinyl alcohol dispersant for 10-15 minutes to prevent clumping; high-activity silica fume with silica content ≥90% and sealed storage, restored to room temperature before use; and polycarboxylate-based water-reducing agent with a water reduction rate ≥25% and diluted before use; then performing staged mixing. In the dry mixing stage, weighed cement, continuously graded crushed stone, medium sand, and silica fume are added to an external forced mixer, and the mixing speed is set to 180-200 r / min. Dry mixing is carried out for 1-2 minutes until the mixture is uniform in color and there is no obvious particle stratification. Fiber dispersion stage. While maintaining a constant rotation speed, slowly add basalt fibers and continue mixing for 30-60 seconds. High-speed shearing in the mixer ensures the fibers are evenly dispersed without agglomeration. In the wet mixing stage, mix water and polycarboxylate superplasticizer evenly and slowly inject into the mixer. Adjust the rotation speed to 220-240 r / min and wet mix for 2-3 minutes, stopping the machine 2-3 times to break up any localized dry clumps. After mixing, check the slump of the concrete mixture and control it to 50-80 mm. If it does not meet the standard, adjust the water volume until it does. Then prepare the molds and pour the concrete into shape, initially using 0.6-0.8MPa compressed air is used to blow away dust and debris from the molding cavity to clean the mold. Next, a water-based release agent is evenly applied to the surfaces of the side mold assembly 4, inner mold assembly 5, replacement insert 10, and floating molding strip 11, and allowed to stand for 5-10 minutes until the release agent forms a film. Then, the mold is poured in two stages. The first stage pours to half the height of the molding cavity and is compacted for 30-40 seconds using a high-frequency vibrator, maintaining a 5-10mm distance between the vibrator and the mold to avoid collision. After compaction, the second stage pours to the top of the mold and is compacted again for 20-30 seconds until the mixture reaches the surface. No air bubbles overflowed, and the slurry flowed evenly. During the pouring process, any overflowing mixture from the mold was promptly cleaned to prevent it from affecting demolding after solidification. Finally, a multi-stage curing process was implemented. In the pre-curing stage, after pouring, the top of the mold was covered with plastic film, and the mold, along with the U-shaped channel blank, was placed in a curing chamber at a temperature of 20–25℃ and a relative humidity ≥90% for 2–4 hours to allow the concrete to initially set and prevent excessive evaporation of surface moisture. After pre-curing, the plastic film was removed, and the mold, along with the blank, was transferred to a steam curing chamber. The curing chamber door was closed, and the steam generator was started at 5–10℃ / The temperature in the curing chamber is raised to 45-55℃ at a heating rate of h, with the temperature recorded every 30 minutes to ensure uniform heating. Once the set temperature is reached, it is maintained at a constant temperature for 6-8 hours, with the relative humidity in the curing chamber ≥95% during this period. Steam is continuously supplied via a steam generator. After the constant temperature period, the temperature is lowered to room temperature at a rate of 3-5℃ / h. Rapid cooling is strictly prohibited during this process to avoid temperature cracks in the concrete. After steam curing is complete, the steam curing chamber door is opened and the chamber is left to stand for 1-2 hours. Then, the mold is removed, first by loosening the tie rod assembly 9, then... Flip the flap support assembly 7, and finally open the enclosed first end mold assembly 1, second end mold assembly 2, and side mold assembly 4 via the rotating shaft assembly 8. Transfer the demolded U-shaped channel to the natural curing area. During this period, cover its surface with burlap sacks or geotextile, and sprinkle water 3-4 times a day to keep the product surface moist. Allow it to cure naturally for 7-14 days. Ensure the ambient temperature is ≥5℃ during curing. If the ambient temperature is <5℃, cover it with rock wool blankets for insulation. After curing, test the 28-day compressive strength of the U-shaped channel to be ≥C30 and the impermeability grade to be ≥P6. If the requirements are met, it is considered a qualified finished product.

[0047] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and these substitutions and modifications are all within the protection scope of this invention.

Claims

1. A height-adjustable U-shaped channel mold, comprising a stable base frame (6) for supporting the overall structure; characterized in that: The stable base frame (6) is provided with a first end mold assembly (1) and a second end mold assembly (2) arranged parallel to the U-shaped channel forming direction. A side mold assembly (4) and an inner mold assembly (5) are arranged between the first end mold assembly (1) and the second end mold assembly (2), which enclose each other to form a U-shaped channel forming cavity. A positioning pin assembly (3) is provided on the first end mold assembly (1) and the second end mold assembly (2), and is connected to the side mold assembly (4) through the positioning pin assembly (3) to provide clearance fit at the mold splicing point and avoid misalignment and leakage. A replacement panel (10) is provided on the inner side wall of the side mold assembly (4) along the height direction. The replacement panel (10) can be disassembled and replaced separately, and a sealing strip is embedded at the splicing seam. A plurality of height adjustment blocks (12) are laid at the bottom of the forming cavity between the inner mold assembly (5) and the side mold assembly (4). The thickness specifications of the ) are in various sizes, which are used for step-by-step adjustment of height to realize the production of U-shaped channels with different height specifications; the uppermost height adjustment block (12) is also provided with a floating forming strip (11) to compensate for the volume shrinkage after concrete pouring in real time and avoid shrinkage cracks; the bottom of the first end mold assembly (1), the second end mold assembly (2) and the side mold assembly (4) are all provided with multiple sets of rotating shaft assemblies (8) and are rotatably connected to the stable base frame (6) through the rotating shaft assembly (8), with a rotation angle of 0° to 90°, which is used to quickly release the enclosure support to assist demolding; the outer walls of the first end mold assembly (1), the second end mold assembly (2) and the side mold assembly (4) are all equipped with flip plate support assemblies (7), and a tie rod assembly (9) is also provided between the first end mold assembly (1) and the second end mold assembly (2) to adjust the tightness of the connection with the side mold assembly (4).

2. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The first end mold assembly (1) includes a first end plate body (102), and a plurality of first connecting partitions (103) are arranged in parallel on the outer end face of the first end plate body (102); a socket forming plate (101) is provided on the inner end face of the first end plate body (102), and a screw fastener (104) is provided on the socket forming plate (101) and is detachably connected to the inner end face of the first end plate body (102) through the screw fastener (104); steel pipes (105) are also symmetrically arranged on both sides of the first end plate body (102), and a clamping block (106) is welded to the outer end of the steel pipe (105).

3. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The second end mold assembly (2) includes a second end plate body (202), and a plurality of second connecting partitions (203) are arranged in parallel on the outer end face of the second end plate body (202); a socket forming plate (201) is provided on the inner end face of the second end plate body (202), and a plurality of mounting positioning holes (206) are evenly spaced on the socket forming plate (201); connecting blocks (204) are also symmetrically arranged on both sides of the second end plate body (202), and an arc plate (205) is welded to the outer end of the connecting block (204).

4. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The side mold assembly (4) includes a symmetrically arranged side mold body (401). Multiple molding blocks (402) are spaced apart on the inner side wall of the side mold body (401) and located at the upper end of the replacement panel (10). Multiple nuts and fasteners (405) are fitted on the replacement panel (10) and are detachably connected to the side mold body (401) through the nuts and fasteners (405). A molding round module (403) is also arranged between the molding blocks (402). A bending plate (404) is provided on the upper outer side of the side mold body (401), and the bending angle of the bending plate (404) is 90°. A reinforcing rib (406) is provided on the lower outer side of the side mold body (401), and several reinforcing ribs (406) are evenly spaced apart.

5. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The stabilizing base frame (6) includes parallel second channel steels (602), and a first channel steel (601) is vertically welded between the second channel steels (602); a third channel steel (601) is welded along the length of the first channel steel (601), the width of the third channel steel (601) corresponds to the bottom width of the inner mold assembly (5), and a number of slots (604) are evenly spaced on it; the welds between the first channel steel (601), the second channel steel (602) and the third channel steel (601) are fully welded, and rust prevention treatment is performed after welding.

6. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The flap support assembly (7) includes a support plate (701), a flap (702), a handle (703), and a bolt and nut connector (704). One end of the support plate (701) is fixedly connected to the outer side wall of the first end mold assembly (1), the second end mold assembly (2), and the side mold assembly (4). The other end of the support plate (701) is rotatably connected to one end of the flap (702) through the bolt and nut connector (704) passing through it, with a rotation angle of 0° to 180°. The free end of the flap (702) is provided with a handle (703), and the outer surface of the handle (703) is covered with an anti-slip rubber sleeve. The handle (703) is turned and drives the flap (702) to rotate, so that the top of the free end of the flap (702) abuts against the stable base frame (6) to provide vertical support force.

7. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The rotating shaft assembly (8) includes a rotating shaft (802), and a copper sleeve (804) is fitted on the outer side of the rotating shaft (802); a straight-through pressure injection cup (801) is provided at one end of the rotating shaft (802), and the oil outlet of the straight-through pressure injection cup (801) is connected to the internal oil passage of the rotating shaft (802) for injecting lubricating oil into the mating surface of the rotating shaft (802) and the copper sleeve (804) to reduce wear; tilting plates (804) are provided on both sides of the copper sleeve (804) on the rotating shaft (802). 3) A fixing plate (805) is symmetrically fitted on the outside of the copper sleeve (804); the fixing plate (805) is welded and fixed to the stable base frame (6); the tilting plate (803) is fixedly connected to the bottom of the first end mold assembly (1), the second end mold assembly (2) and the side mold assembly (4) respectively; the other end of the rotating shaft (802) is provided with an annular groove, and a shaft elastic retaining ring (806) is inserted in the annular groove to limit the axial displacement of the rotating shaft (802) during operation.

8. The height-adjustable U-shaped channel mold according to claim 1, characterized in that: The pull rod assembly (9) includes a connecting pull rod (902), a flip claw (904), and a connecting pin (905); one end of the connecting pull rod (902) is equipped with a flange nut fastener (901), and the other end is provided with a pull plate (903); the connecting pin (905) is provided on the pull plate (903), and the flip claw (904) is rotatably connected to the pull plate (903) through the connecting pin (905); the connecting pull rod (902) abuts against the second end mold assembly (2) through the flange nut fastener (901), and the connecting pull rod (902) is clamped on the first end mold assembly (1) through the pull plate (903) and the flip claw (904); a pressure rod (906) is also connected to the flip claw (904), and when the pressure rod (906) is moved, it drives the flip claw (904) to rotate, thereby achieving clamping or loosening with the first end mold assembly (1).

9. A method for preparing a special material for U-shaped channel forming, characterized in that: Includes the following steps: Step 1: Raw material pretreatment and precise batching. Silicate cement is selected and sieved through an 80-mesh screen before use to remove agglomerated particles. Continuously graded granite crushed stone with a particle size of 5–20 mm, a mud content ≤1%, and a needle-like / flaky particle content ≤5% is selected; it is rinsed with clean water until the surface is free of dust and then dried to a moisture content ≤1%. Medium sand with a fineness modulus of 2.3–3.0, a mud content ≤3%, and a mud lump content ≤1% is selected; it is dried to a moisture content of 3–5%. Pure tap water with a pH of 6.5–7.5 is used. Basalt fiber is selected and pretreated with 0.5% polyvinyl alcohol dispersant for 10–15 minutes to prevent clumping. High-activity silica fume with a silica content ≥90% is selected; it is stored in a sealed container and allowed to return to room temperature before use. Polycarboxylate superplasticizer with a water reduction rate ≥25% is selected and diluted before use. Step Two: Staged Mixing and Stirring. In the dry mixing stage, add the weighed cement, continuously graded crushed stone, medium sand, and silica fume to an external forced mixer. Set the mixing speed to 180–200 rpm and dry mix for 1–2 minutes until the mixture is uniform in color and shows no obvious particle stratification. In the fiber dispersion stage, maintain the constant speed and slowly add basalt fibers, continuing to mix for 30–60 seconds. The high-speed shearing of the mixer ensures the fibers are evenly dispersed without agglomeration. In the wet mixing stage, mix water and polycarboxylate superplasticizer evenly and slowly inject into the mixer. Adjust the speed to 220–240 rpm and wet mix for 2–3 minutes. During this period, stop the machine 2–3 times to observe and break up any localized dry clumps. After mixing, check the slump of the concrete mixture, controlling it to 50–80 mm. If it does not meet the standard, adjust the water amount until it does. Step 3: Mold preparation and casting. First, clean the mold by blowing away dust and debris from the molding cavity with compressed air at 0.6-0.8 MPa. Then, evenly apply water-based release agent to the surfaces of the side mold assembly (4), inner mold assembly (5), replacement panel (10), and floating molding strip (11), and let it stand for 5-10 minutes until the release agent forms a film. Then, cast the mixture in two stages. The first stage is to cast to half the height of the molding cavity and vibrate with a high-frequency vibrator for 30-40 seconds. The vibrator should be 5-10 mm away from the mold to avoid collisions. After vibration, cast the mixture to the top of the mold and vibrate again for 20-30 seconds until there are no bubbles overflowing from the surface of the mixture and the slurry is uniform. During the casting process, clean up any mixture overflowing from the mold in time to prevent it from solidifying and affecting demolding. Step 4: Multi-stage curing treatment. The pre-curing stage involves covering the top of the mold with plastic film after pouring, placing the mold and the U-shaped channel blank in a curing chamber at a temperature of 20-25℃ and relative humidity ≥90% for 2-4 hours to allow the concrete to initially set and prevent excessive evaporation of surface moisture. The steam curing stage involves removing the plastic film after pre-curing, transferring the mold and blank into the steam curing chamber, closing the chamber door, and starting the steam generator to raise the temperature to 45-55℃ at a rate of 5-10℃ / h. The temperature is recorded every 30 minutes to ensure uniform heating. Once the set temperature is reached, maintain constant temperature curing for 6-8 hours, with relative humidity ≥95% during this period, and continuously replenish steam through the steam generator. After the constant temperature period, lower the temperature at a rate of 3-5℃ / h. When the temperature reaches room temperature, rapid cooling is strictly prohibited during the cooling process to avoid temperature cracks in the concrete. The natural curing stage is as follows: after steam curing is completed, open the door of the steam curing chamber, let it stand for 1 to 2 hours, then remove the mold, first loosen the tie rod assembly (9), then flip the flip plate support assembly (7), and finally open the enclosed first end mold assembly (1), second end mold assembly (2) and side mold assembly (4) through the rotating shaft assembly (8) to transfer the demolded U-shaped channel to the natural curing area. During this period, cover the surface with burlap sacks or geotextile, sprinkle water 3 to 4 times a day to keep the product surface moist, and cure naturally for 7 to 14 days. At the same time, ensure that the ambient temperature is ≥5℃ during the curing period. If the ambient temperature is <5℃, it is necessary to cover it with rock wool blankets for heat preservation. After curing is completed, test the 28-day compressive strength of the U-shaped channel to be ≥C30 and the impermeability grade to be ≥P6. If the requirements are met, it is a qualified finished product.

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