Deepwater pressure-resistant shell pouring device and method

Abstract

The invention provides a deepwater pressure-resistant shell pouring device and method.The pouring device comprises a first mold and a second mold, the first mold comprises a first outer template, a first reinforcement cage and a first inner template, and the first reinforcement cage is located between the first outer template and the first inner template; the hemispherical end cover comprises a second outer template, a second reinforcement cage and a second inner template, and the second reinforcement cage is located between the second outer template and the second inner template; and ultra-high performance concrete is poured between the first outer formwork and the first inner formwork, ultra-high performance concrete is poured between the second outer formwork and the second inner formwork, and the ultra-high performance concrete, the first reinforcement cage and the second reinforcement cage jointly form the deepwater pressure-resistant shell. The deep-water pressure-resistant shell is poured through the pouring device, high-quality construction of the concrete deep-water pressure-resistant shell is achieved, the crack resistance and stability of the whole structure are improved, and corrosion resistance is enhanced.

Description

Technical Field

[0001] This invention relates to the field of deep-water structure engineering technology, and in particular to a deep-water pressure hull casting device and casting method. Background Technology

[0002] Currently, deep-water pressure-resistant concrete structures typically use ordinary high-strength concrete as the main material. A reinforcing cage is formed by binding a single layer of ordinary steel bars. After the reinforcing cage is placed into an integral steel mold, concrete is poured in one go or in layers without a specified thickness requirement. During vibration, there are no fixed insertion depth or spacing standards, and the operation relies solely on the experience of the construction personnel. After pouring, natural curing or simple steam curing at a constant temperature is mostly used. There are no uniform regulations for curing time. The formwork is removed directly after the concrete surface hardens. Some structures are coated with an ordinary asphalt-based anti-corrosion coating, relying on the compressive strength of the concrete itself and the crack resistance of the reinforcing steel to resist external pressure.

[0003] In existing technologies, the mix proportions of ordinary high-strength concrete used in deep-water pressure-resistant concrete structures have not been scientifically optimized, resulting in large performance fluctuations, low compressive strength, and difficulty in consistently achieving the mechanical properties required for deep-water pressure resistance. Furthermore, the concrete has weak resistance to seepage, corrosion, and aging, and is prone to pore penetration during long-term seawater immersion, leading to a decrease in structural strength. In addition, the concrete relies solely on ordinary steel reinforcement without combining it with high-tensile and corrosion-resistant composite materials, resulting in poor overall crack resistance. During pouring and transportation, through-cracks are easily formed due to stress concentration.

[0004] Due to the lack of standardized control in the construction process of deep-water pressure-resistant concrete structures, phenomena such as air bubbles and honeycomb pitting are easily generated during concrete pouring, the pouring quality cannot be guaranteed, thermal stress cracks are easily generated inside, the protective layer has poor adhesion and is easy to fall off, and the sealing performance of deep-water pressure-resistant concrete structures cannot be guaranteed. Summary of the Invention

[0005] The purpose of this invention is to provide a deep-water pressure hull casting device and casting method, which realizes the high-quality construction of concrete deep-water pressure hulls, improves the crack resistance and stability of the overall structure, and enhances the corrosion resistance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A deep-water pressure hull casting device is disclosed. The deep-water pressure hull includes a cylindrical section and two hemispherical end caps respectively disposed at both ends of the cylindrical section. The casting device includes two molds, namely a first mold and a second mold. The first mold is used to cast the cylindrical section, and the second mold is used to cast the hemispherical end caps. The first mold includes a first outer template, a first reinforcing cage, and a first inner template, with the first reinforcing cage located between the first outer template and the first inner template. The hemispherical end cap includes a second outer template, a second reinforcing cage, and a second inner template, with the second reinforcing cage located between the second outer template and the second inner template. Ultra-high performance concrete is cast between the first outer template and the first inner template, and ultra-high performance concrete is cast between the second outer template and the second inner template. After the two second molds and the first mold are spliced ​​and disassembled, the ultra-high performance concrete, the first reinforcing cage, and the second reinforcing cage together form the deep-water pressure hull.

[0007] Furthermore, in the aforementioned deep-water pressure hull casting device, the casting device also includes a base and a flange. The base is made of steel plate, and its upper surface is provided with a groove. The groove is annular, and its width matches the thickness of the first inner template. A sponge strip is pasted inside the groove. The first inner template is cylindrical, and it is composed of multiple arc-shaped cold-rolled steel plates. The lower end of the first inner template can be inserted into the groove on the base, and the upper end of the first inner template is provided with a cylindrical mold fixing fixture. The cylindrical mold fixing fixture consists of an annular positioning ring and two positioning plates. The two positioning plates are arranged in a cross shape inside the positioning ring. Multiple top supports extending towards the center of the positioning ring are provided on the inner wall of the positioning ring. The inner diameter of the positioning ring is the same as the inner diameter of the first outer template, and the multiple top supports are symmetrically distributed. The first reinforcing cage includes multiple longitudinal bars, multiple stirrups, and a carbon fiber mesh. Both the base and the cylindrical mold fixing fixture are provided with several positioning holes. The longitudinal bars are vertically arranged, and the multiple longitudinal bars are evenly distributed... The longitudinal reinforcement bars are arranged around the first inner template, with their ends located in the positioning holes on the positioning ring and the base, respectively. The carbon fiber mesh is wrapped around the outside of the longitudinal reinforcement bars, and the stirrups are sleeved on the outside of the carbon fiber mesh. Multiple stirrups are evenly distributed along the height direction of the carbon fiber mesh. The intersection of the longitudinal reinforcement bars, the stirrups, and the carbon fiber mesh is used for binding and fixing to form the first reinforcing cage. The first outer template is a cylinder, and it is made of multiple arc-shaped cold-rolled steel plates spliced ​​together. The joints of the multiple arc-shaped cold-rolled steel plates are fastened by connecting ear plates and bolts. The diameter of the first outer template is larger than that of the first inner template. The flange is set on the base, and the inner diameter of the flange is consistent with the outer diameter of the groove. The lower end of the first outer template and the bottom of the first inner template are connected by the flange. The carbon fiber mesh is a bidirectional structure, and the material of the carbon fiber mesh is a carbon fiber reinforced composite material of carbon fiber filaments and resin matrix. A steel sleeve is welded at the splice of the second mold and the first mold as a reserved rebar hole.

[0008] Furthermore, in the aforementioned deep-water pressure-resistant shell casting device, the second outer template is hemispherical, and is composed of multiple cold-rolled steel plates in the shape of spherical petals. The second outer template is mounted on a fixed support, the shape of the upper surface of which is adapted to the outer surface of the second outer template; the second reinforcing cage is composed of reinforcing bars and carbon fiber mesh, and is hemispherical, with its outer diameter smaller than the inner diameter of the second outer template and its inner diameter larger than the outer diameter of the second inner template; the second inner template is hemispherical, and is composed of multiple transparent acrylic plates in the shape of spherical petals. The second outer template and the second inner template are also connected by a spherical mold fixing fixture; the spherical mold fixing fixture includes a fixing plate and a fixing frame. The fixing plate has a circular cross-section and covers the bottom surface of the hemispherical end cap. The fixing plate is connected to both the second inner template and the second outer template. Multiple fan-shaped grouting ports are evenly arranged circumferentially on the fixing plate. Ultra-high performance concrete can be poured between the second outer template and the second inner template through the grouting ports. A cover plate is provided at the grouting port, and the shape of the cover plate is adapted to the shape of the grouting port. A steel sleeve is welded to the bottom surface of the second reinforcing cage as a reserved rebar anchoring hole.

[0009] On the other hand, a method for casting a deep-water pressure hull is provided, which utilizes the aforementioned deep-water pressure hull casting apparatus and includes the following steps: Step 1: Fabricate a deep-water pressure hull casting device. The first mold is made using the first outer formwork, the first inner formwork, and the first reinforcing cage; the second mold is made using the second outer formwork, the second inner formwork, and the second reinforcing cage. Step 2: Mixing and pouring ultra-high performance concrete. Ultra-high performance concrete was mixed according to the optimized mix proportion and poured into the first and second molds in layers. After each layer was poured, it was vibrated to ensure that the concrete was dense. Step 3, steam curing and demolding. After the concrete has initially set, the mold is subjected to stepped steam curing. Once the concrete reaches the designed demolding strength, the mold is removed and subsequent curing is carried out to complete the casting of the cylindrical section and the hemispherical end cap. Step 4: Arrange the measuring points and straighten the lead wires. Strain gauges and pressure sensors are arranged on the inner surface of the cured casting according to a preset pattern, and the strain gauges and pressure sensors are waterproofed. The leads of the strain gauges are led out through the pre-embedded wire guide. Step 5, assemble and seal. The demolded cylindrical section and hemispherical end cap are assembled to form a deep-water pressure-resistant shell; Step 6, Quality Inspection The deep-water pressure hull is subjected to visual inspection, water pressure sealing test and strength verification.

[0010] Furthermore, in the above-mentioned method for casting deep-water pressure hulls, Step 1 specifically includes: Step 11, mold pretreatment: apply an oil-based release agent to the surfaces of the first outer mold plate, the first inner mold plate, the second outer mold plate, and the second inner mold plate. Step 12: The cylindrical section is molded together. A base is made using a steel plate. The top surface of the base is calibrated using a level. The base is fixed to the working surface using expansion bolts. A groove with a width matching the thickness of the first inner template is reserved on the base. Thick sponge strips are pasted into the groove. The flange is placed on the base. The first inner template is inserted into the groove of the base, with the lower edge of the first template completely embedded in the sponge strip in the groove. The first template and the flange are welded together. A cylindrical mold fixing fixture is installed at the upper end of the first inner template. The longitudinal reinforcement is evenly arranged around the first inner template through the positioning holes on the base and the cylindrical mold fixing fixture. The carbon fiber mesh is wrapped around the outside of the longitudinal reinforcement. Finally, according to the stirrup spacing designed in the drawings, the stirrups are fitted onto the carbon fiber mesh. Ties are used to secure the carbon fiber mesh in overlapping areas and at the intersections of the carbon fiber mesh, longitudinal reinforcement, and stirrups to form the first reinforcing cage. The first outer template is installed. Tie bolts are placed between the back ribs of the first outer template and the inner template. The bolt holes are precisely machined using a hole saw. The tie bolts are tightened, and the flatness of the template surface is checked. Step 13, hemispherical end cap mold closing: First, fix the second outer template with a fixed bracket. The second outer template is made of cold-rolled steel plates in the shape of prefabricated spherical petals. Place the second steel cage inside the second outer template. Then, install the second inner template. The second inner template is made of transparent acrylic sheets. The joints are sealed with special glue and reinforced with fiberglass cloth. Hoist it with a ball mold fixing fixture. After it is lowered into place, use the ball mold fixing fixture to connect and fix the second inner template to the second outer template. Step 14, mold measurement: Measure the dimensions of the first and second molds after they are closed to ensure that the mold dimensions meet the design standards. At the same time, check that the molds are free from deformation and correctly assembled, and record the specimen model and casting date on the outer surface of the molds.

[0011] Furthermore, in the above-mentioned deep-water pressure-resistant shell casting method, in step 2, the mix proportion is optimized through a four-factor multi-level orthogonal experiment to ensure that the compressive strength of the ultra-high performance concrete is greater than 120 MPa; the ultra-high performance concrete is poured into the first mold and the second mold in layers, and each layer is vibrated after pouring. After pouring, the concrete is allowed to stand still, and grout is continuously added during the stand-up period. During the stand-up period, the concrete must be protected from freezing, and steam preheating is required before the temperature drops to 0℃; at the same time, cubic concrete specimens are poured simultaneously when pouring each mold, which are used for subsequent strength testing in conjunction with the implosion test to verify whether the compressive strength of the concrete meets the standard; when pouring concrete in layers, the concrete is poured into the mold in layers with a thickness of 5cm-10cm each time, and the thickness of each layer is 5cm-10cm, filling the entire first and second reinforcing cages layer by layer, ensuring that the first and second reinforcing cages are completely embedded in the concrete.

[0012] Furthermore, in the above-mentioned deep-water pressure-resistant shell casting method, in step 3, the stepped steam curing includes three stages: heating at a certain rate, maintaining a constant temperature, and cooling steadily. The specific parameters of the stepped steam curing are as follows: In the heating stage, the heating rate is controlled, and the temperature of the curing chamber is slowly increased from room temperature to the target temperature, with the heating rate controlled within 10℃ / h, until the set temperature of 75℃±5℃ is reached; In the constant temperature stage, the temperature is kept constant and the relative humidity is higher than 95%. Steam supply is used to ensure that the concrete surface is moist to prevent dehydration, shrinkage, and cracking. The constant temperature steam curing is carried out for 8 hours at the target temperature. After a certain period of time, the concrete enters the cooling stage. During the cooling stage, the concrete cools down steadily to near room temperature at a relatively slow rate, with the cooling rate controlled to not exceed 10°C per hour. Before demolding, it is necessary to confirm that the concrete has reached the demolding strength of the design strength. When demolding, first grind the surface of the cast part to remove excess concrete and ensure flatness. Then adjust the radius of the first or second inner template to separate the cast part from the template. Use hoisting equipment to remove the first or second inner template. Finally, loosen the fixing bolts on the outside of the mold and disassemble the mold. After demolding, the cast parts of the cylindrical section and hemispherical end cap need to be properly cured to ensure the continuous growth of the concrete strength in the later stage.

[0013] Furthermore, in the above-mentioned casting method for deep-water pressure hull, in step 4, strain gauges and pressure sensors are arranged on the inner surface of the cured casting according to a preset pattern. The strain gauges and pressure sensors are bonded to the inner surface of the casting using epoxy resin adhesive and waterproofed. The leads of the strain gauges and pressure sensors are led out through a pre-embedded wire guide. The strain gauges are arranged on the inner surface of the cylindrical section casting. The strain gauges include circumferential strain gauges and longitudinal strain gauges. The circumferential strain gauges are evenly arranged in 2-4 rings along the axial direction of the cylindrical section, with 4 circumferential strain gauges evenly arranged in each ring. The circumferential strain gauges are used to record the radial contraction and expansion behavior of the deep-water pressure hull. Two longitudinal strain gauges are arranged around two adjacent circumferential strain gauges. The longitudinal strain gauges are used to monitor the axial strain state. The leads of the strain gauges and pressure sensors are led out to the external strain gauge through the wire guide. The wire guide also serves as the inlet and outlet.

[0014] Furthermore, in the above-mentioned deep-water pressure hull casting method, in step 5, a waterproof coating with epoxy resin as the main component is brushed onto the outer surface, splicing surface and inner surface of the casting component. The splicing surface is treated, and the anchoring adhesive is injected into the anchoring holes. A thick layer of grout is applied to the splicing surface, followed by brushing on an epoxy resin layer and injecting adhesive. The cylindrical section and hemispherical end cap are assembled. After the grout has completely solidified, the assembly and sealing of the deep-water pressure hull is completed.

[0015] Furthermore, in the above-mentioned deep-water pressure-resistant shell casting method, in step 6, after assembly, the structural integrity of the deep-water pressure-resistant shell is confirmed by visual inspection, and it is free from cracks and deformation. Water is injected into the deep-water pressure-resistant shell using a wire drill, and the water pressure is used to verify the sealing performance of the deep-water pressure-resistant shell. At the same time, a strength test is carried out using a cube specimen cast simultaneously to confirm that the compressive strength of the concrete meets the requirements, and that the quality of the deep-water pressure-resistant shell meets the design requirements.

[0016] Analysis reveals that this invention discloses a deep-water pressure hull casting device and method. Through a four-factor, multi-level orthogonal experiment, the optimal mix proportion of concrete with high compressive strength is selected, solving the problems of unstable concrete performance and insufficient strength in existing technologies, thus providing a reliable material foundation for deep-water pressure hulls. A composite reinforcement cage, using ordinary steel bars and carbon fiber mesh for synergistic binding, enhances both the structural crack resistance and corrosion resistance of the deep-water pressure hull, preventing cracking and overcoming the shortcomings of existing single-reinforcement structures. The invention solves the problem of casting large-volume, thin-walled concrete shells by simultaneously casting cubic strength specimens to verify quality in real time, and by layering and vibrating the concrete to ensure density. A stepped steam curing system is adopted to control the temperature difference between the inside and outside of the concrete, avoiding thermal stress cracks; and the demolding strength is clearly defined to protect the integrity of the deep-water pressure hull. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a three-dimensional structural diagram of the first template according to an embodiment of the present invention.

[0018] Figure 2 This is a three-dimensional structural diagram of the second template according to an embodiment of the present invention.

[0019] Figure 3 This is a flowchart of a method for casting a deep-water pressure hull according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 1. First outer formwork; 2. First reinforcing cage; 3. First inner formwork; 4. Second outer formwork; 5. Second reinforcing cage; 6. Second inner formwork; 7. Base; 8. Flange; 9. Cylindrical formwork fixing fixture; 10. Positioning ring; 11. Positioning plate; 12. Top support; 13. Fixing bracket; 14. Ball formwork fixing fixture; 15. Fixing plate; 16. Fixing frame; 17. Cover plate. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. Indeed, those skilled in the art will recognize that modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention encompass such modifications and variations falling within the scope of the appended claims and their equivalents.

[0022] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," 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 do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected," "linked," and "set up" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection through intermediate components; a wired connection, a radio connection, or a wireless communication signal connection. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0023] The accompanying drawings illustrate one or more examples of the invention. The detailed description uses numerals and letters to refer to features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to refer to similar or analogous parts of the invention. As used herein, the terms “first,” “second,” and “third,” etc., are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of individual components.

[0024] like Figures 1 to 3 As shown in the embodiment of the present invention, a deep-water pressure hull casting device is provided. The deep-water pressure hull includes a cylindrical section and two hemispherical end caps respectively disposed at both ends of the cylindrical section. The casting device includes two molds, namely a first mold and a second mold. The first mold includes a first outer template 1, a first reinforcing cage 2 and a first inner template 3, with the first reinforcing cage 2 located between the first outer template 1 and the first inner template 3. The second mold includes a second outer template 4, a second reinforcing cage 5 and a second inner template 6, with the second reinforcing cage 5 located between the second outer template 4 and the second inner template 6. Ultra-high performance concrete is poured between the first outer template 1 and the first inner template 3, and ultra-high performance concrete is poured between the second outer template 4 and the second inner template 6. After the two second molds and the first mold are spliced ​​and disassembled, the ultra-high performance concrete, the first reinforcing cage 2 and the second reinforcing cage 5 together form the deep-water pressure hull.

[0025] Furthermore, such as Figure 1 As shown, the pouring device also includes a base 7 and a flange 8. The base 7 is made of steel plate, and a groove is provided on the upper surface of the base 7. The groove is annular, and the width of the groove matches the thickness of the first inner template 3. A sponge strip is pasted inside the groove. The lower end of the first inner template 3 can be inserted into the groove. When pouring the cylindrical section, the sponge strip in the groove of the base 7 can prevent concrete leakage.

[0026] The first inner template 3 is a cylinder, and is made of multiple arc-shaped cold-rolled steel plates. The lower end of the first inner template 3 can be inserted into the groove on the base 7. The upper end of the first inner template 3 is provided with a cylinder mold fixing fixture 9, which consists of an annular positioning ring 10 and two positioning plates 11. The two positioning plates 11 are arranged in a cross shape inside the positioning ring 10. Multiple top supports 12 extending towards the center of the positioning ring 10 are provided on the inner wall of the positioning ring 10. The inner diameter of the positioning ring 10 is the same as the inner diameter of the first outer template 1, and the multiple top supports 12 are symmetrically distributed. The first reinforcing cage 2 includes multiple longitudinal bars, multiple stirrups, and carbon fiber mesh. The base 7 and the cylinder mold fixing fixture 9 are both provided with several positioning holes. The longitudinal bars are arranged vertically, and the multiple longitudinal bars are evenly distributed around the first inner template 3. The two ends of the longitudinal bars are respectively located at the positioning holes. In the positioning holes on ring 10 and base 7, carbon fiber mesh is wrapped around the outside of the longitudinal reinforcement, and stirrups are sleeved on the outside of the carbon fiber mesh. Multiple stirrups are evenly distributed along the height direction of the carbon fiber mesh. The intersection of the longitudinal reinforcement, stirrups and carbon fiber mesh is used for binding and fixing to form the first reinforcing cage 2. The first outer template 1 is a cylinder. The first outer template 1 is spliced ​​from multiple arc-shaped cold-rolled steel plates. The joints of the multiple arc-shaped cold-rolled steel plates are fastened by connecting ear plates and bolts. The diameter of the first outer template 1 is larger than the diameter of the first inner template 3. The flange 8 is set on base 7. The inner diameter of the flange 8 is consistent with the outer diameter of the groove. The lower end of the first outer template 1 and the bottom of the first inner template 3 are connected by the flange 8. The carbon fiber mesh is a two-way structure. The material of the carbon fiber mesh is carbon fiber reinforced polymer (CFRP) composite material of carbon fiber filament and resin matrix. The first reinforcing cage 2 formed by the longitudinal reinforcement, stirrups and carbon fiber mesh can significantly improve the crack resistance and corrosion resistance of the deep-water pressure hull. The two ends of the first steel cage 2 are welded with steel sleeves as reserved holes for rebar installation.

[0027] The first mold adopts a double-layer steel plate structure (first inner template 3 and first outer template 1). The flange 8 is set on the base 7. The first inner template 3 is welded to the inside of the flange 8, and the first outer template 1 is welded to the outside of the flange 8 to enhance local rigidity, prevent stress concentration cracking, and form a complete steel inner mold system.

[0028] Furthermore, such as Figure 2As shown, the second outer template 4 is hemispherical and is made of multiple cold-rolled steel plates in the shape of spherical petals. The second outer template 4 is set on the fixed bracket 13, and the shape of the upper surface of the fixed bracket 13 is adapted to the outer surface of the second outer template 4. The second reinforcing cage 5 is made of reinforcing bars and carbon fiber mesh. The second reinforcing cage 5 is hemispherical. The second inner template 6 is hemispherical and is made of multiple transparent acrylic plates in the shape of spherical petals. The second outer template 4 and the second inner template 6 are also connected and fixed by a spherical mold fixing fixture 14. The ball mold fixing fixture 14 includes a fixing plate 15 and a fixing frame 16. The fixing plate 15 has a circular cross-section and covers the bottom surface of the hemispherical end cap. The fixing plate 15 is connected to both the second inner template 6 and the second outer template 4. Multiple fan-shaped grouting ports are evenly arranged on the fixing plate 15 along the circumference. Ultra-high performance concrete can be poured between the second outer template 4 and the second inner template 6 through the grouting ports. A cover plate 17 is provided at the grouting port, and the shape of the cover plate 17 is adapted to the shape of the grouting port. A steel sleeve is welded at the joint between the second mold and the first mold as a reserved rebar hole.

[0029] This invention also discloses a method for casting a deep-water pressure hull, utilizing the aforementioned deep-water pressure hull casting apparatus, such as... Figure 3 As shown, it includes the following steps: Step 1: Construct a deep-water pressure-resistant shell casting device. This involves creating a first mold using the first outer formwork 1, the first inner formwork 3, and the first reinforcing cage 2; and creating a second mold using the second outer formwork 4, the second inner formwork 6, and the second reinforcing cage 5. Specifically, this includes: Step 11, mold pretreatment, An oil-based release agent is brushed onto the surfaces of the first outer template 1, the first inner template 3, the second outer template 4, and the second inner template 6 to facilitate smooth demolding of the mold.

[0030] Step 12, close the cylindrical section mold. A base 7 is made of steel plate. The working surface is leveled, and the base 7 is placed on the working surface. The top surface of the base 7 is calibrated with a level to reduce errors. Then, the base 7 is fixed to the working surface with expansion bolts to prevent displacement during the pouring process. A groove with a width matching the thickness of the first inner template 3 is reserved on the base 7. Thick sponge strips are pasted in the groove to prevent leakage when pouring concrete into the cylindrical section. Positioning axes are marked on the base 7 on both sides of the groove as a reference for the installation of the first inner template 3. The flange 8 is placed on the base 7.

[0031] Insert the first inner template 3 into the groove of the base 7. The lower edge of the first template is completely embedded in the sponge strip in the groove. The verticality of the first inner template 3 is calibrated by plumb bob. The first template and the flange 8 are welded together. The installation of the first inner template 3 is completed.

[0032] A cylindrical mold fixing fixture 9 is installed at the upper end of the first inner mold 3. The cylindrical mold fixing fixture 9 consists of a positioning ring 10, a positioning plate 11, and a top support 12. Positioning holes are reserved on the positioning plate 11 and the top support 12. The longitudinal reinforcement bars are evenly arranged around the first inner mold 3 through the positioning holes on the base 7 and the fixing fixture, ensuring that each longitudinal reinforcement bar is vertical. The carbon fiber mesh is wrapped around the outside of the longitudinal reinforcement bars, ensuring that the carbon fiber mesh is tightly attached to the longitudinal reinforcement bars. Finally, according to the stirrup spacing designed in the drawings, the stirrups are fitted onto the carbon fiber mesh, and multiple stirrups are evenly placed along the height direction of the first inner mold 3. Tie wire is used to bind and fix the carbon fiber mesh in the overlapping area and at the intersection of the carbon fiber mesh, longitudinal reinforcement bars, and stirrups to form the first reinforcing cage 2, preventing the carbon fiber mesh and reinforcing bars from slipping or misaligning. A fixing nut is provided at the upper end of the longitudinal reinforcement. Tighten the fixing nut to fix the first steel cage 2 in the center. When adjusting the fixing nut, a torque wrench should be used to control the tightening force to prevent excessive compression that could cause the steel cage to deform. The position of the first steel cage 2 should be checked again to ensure that the error of the overlap between its axis and the axis of the first inner formwork 3 is within the allowable range.

[0033] Install the first outer template 1. The first outer template 1 adopts a modular design and is assembled piece by piece from one side during installation. The joints are secured with connecting ear plates and connecting bolts. Finally, tie bolts are installed between the back ribs of the first outer template 1 and the inner template. The bolt holes are precisely machined using a hole saw. Tighten the tie bolts and check the flatness of the template surface.

[0034] Step 13, close the hemispherical end cap mold. The hemispherical end cap mold closing process requires controlling the curvature accuracy of the cold-rolled steel plates of the spherical petals and the positioning accuracy of the second reinforcing cage 5. First, the second outer template 4 is fixed using a fixed bracket 13. The second outer template 4 and the fixed bracket 13 can be connected by welding or bolts. The second outer template 4 is constructed from prefabricated, spherical-shaped cold-rolled steel plates, and is supported by the fixed bracket 13. Before installation, the center position of the hemispherical second outer template 4 is marked on the fixed bracket 13. Using the center as a reference, the chord angle of each cold-rolled steel plate is adjusted. The continuity of the cold-rolled steel plate's curvature is checked using a string line method. Then, adjacent cold-rolled steel plates are fastened together with tie bolts.

[0035] After the second outer formwork 4 is fixed, the second reinforcing cage 5 is placed inside it. The second reinforcing cage 5 is pre-tied into a hemispherical shape according to the designed curvature in the processing area. The hooks welded to the ends of the main reinforcing bars must face the inside of the cage. During hoisting, a special balance beam is used to keep the second reinforcing cage 5 horizontal. During placement, the positioning marks on the second reinforcing cage 5 are aligned with the baseline of the second outer formwork 4. Then, the second inner formwork 6 is placed. The second inner formwork 6 is made of transparent acrylic sheets, with the joints sealed with special adhesive and reinforced with fiberglass cloth. It is hoisted using a ball mold fixing fixture 14, lowered slowly to avoid scratching the second reinforcing cage 5. After lowering into place, the ball mold fixing fixture 14 is used to connect and fix the second inner formwork 6 to the second outer formwork 4. The use of transparent acrylic sheets for the second inner formwork 6 allows for convenient real-time monitoring of the pouring process within the second mold.

[0036] Step 14, Mold Measurement: Measure the dimensions of the first and second molds after they are assembled to ensure that the mold dimensions meet the design standards. The mold thickness should be measured at least at three corners (measured once every 120°) to strictly control the error. At the same time, check that the mold is free from deformation and correctly assembled, and record the specimen model and casting date on the outer surface of the mold.

[0037] Step 2: Mixing and pouring ultra-high performance concrete. Ultra-High Performance Concrete (UHPC) was prepared according to the optimized mix proportions. The UHPC was then poured into the first and second molds in layers. After each layer was poured, it was vibrated to ensure that the concrete was compacted.

[0038] The mix proportion was optimized through a four-factor, multi-level orthogonal experiment to achieve a compressive strength greater than 120 MPa for ultra-high performance concrete. During the orthogonal experiment, the water-cement ratio, total sand-cement ratio, and water-reducing agent dosage remained constant. Four variables—fly ash content, silica fume content, steel fiber content, and cement type—were used in the multi-level orthogonal experiment. Based on the orthogonal experiment results, a mix proportion with high compressive strength, flexural strength, and axial compressive strength was selected to ensure stable concrete performance that meets the requirements for deep-water pressure resistance. In one embodiment of this invention, the orthogonal experiment variables are shown in Table 1, and the optimized mix proportion of the ultra-high performance concrete is shown in Table 2.

[0039] Table 1: Variables for Orthogonal Experiments Table 2: Optimized Ultra-High Performance Concrete Mix Proportion When mixing concrete, raw materials are prepared according to the optimized mix proportions. First, dry materials such as cement, quartz sand, silica fume, and fly ash are premixed and then put into a mixer for dry mixing. Then, water is slowly added and stirred until the mixture reaches a cohesive state. Finally, steel fibers are added while continuously stirring until there are no lumps and the consistency is uniform. The compressive strength of the mixed ultra-high performance concrete must be greater than 120 MPa to withstand the high pressure, penetration, and corrosion of the deep sea.

[0040] Before pouring, the molds are inspected to ensure they are secure and accurately positioned. Then, pouring begins, with ultra-high performance concrete poured in layers into the first and second molds. Each layer is vibrated after pouring to ensure it is dense and free of air bubbles. When pouring the cylindrical section, concrete is poured in layers of a certain thickness, gradually filling the mold and ensuring the first reinforcing cage 2 is fully embedded. When pouring the hemispherical end cap, concrete is poured through the grouting port, using a pre-welded steel sleeve to pre-reserve anchoring holes. The concrete filling in all areas must be slightly higher than the mold to prevent settlement below the design height; grouting should be added promptly after settlement. A circular hole is pre-drilled at the top of the second mold during pouring to accommodate a wire guide, which consists of a PTFE sealing ring, an embedded bolt, and a rubber ring.

[0041] After pouring, the concrete is allowed to stand still. During the stand-up period, grout is continuously added. During the stand-up period, the concrete must be protected from freezing. Steam preheating is required before the temperature drops to 0℃. At the same time, cubic concrete specimens are poured simultaneously when pouring each mold. These specimens are used for subsequent strength testing in conjunction with the implosion test to verify whether the compressive strength of the concrete meets the standard.

[0042] When pouring concrete in layers, the concrete is poured into the mold in layers of 5cm-10cm thickness each time. The thickness of each layer is 5cm-10cm, and the entire first steel cage 2 and the second steel cage 5 are filled layer by layer to ensure that the first steel cage 2 and the second steel cage 5 are completely embedded in the concrete.

[0043] Step 3, steam curing and demolding. After the concrete has initially set, the mold is subjected to stepped steam curing. Once the concrete reaches the designed demolding strength, the mold is removed and subsequent curing is carried out. Stepped steam curing includes three stages: heating at a certain rate, maintaining a constant temperature, and cooling down steadily.

[0044] The cast cylindrical section and hemispherical end cap are subjected to stepped steam curing. Specific parameters for stepped steam curing are as follows: During the heating phase, the heating rate is controlled, with the curing chamber temperature slowly increasing from room temperature to the target temperature at a rate not exceeding 10℃ / h, until the set temperature of 75℃±5℃ is reached. During the constant temperature phase, the temperature is kept constant and the relative humidity is above 95%. Steam supply ensures the concrete surface remains moist to prevent dehydration, shrinkage, and cracking. Constant temperature steam curing is carried out for at least 8 hours at the target temperature (75℃±5℃). After reaching the preset curing age, the cooling phase begins. During the cooling phase, the temperature is gradually and steadily reduced to near room temperature, with the cooling rate controlled not exceeding 10℃ per hour, until the cast part temperature returns to room temperature to avoid excessive temperature differences that could cause thermal stress cracks. Once the concrete reaches the designed demolding strength, demolding and subsequent curing are carried out.

[0045] Before demolding, it is necessary to confirm that the concrete has reached the demolding strength of the design strength. When demolding, first grind the pouring surface, remove excess concrete and ensure flatness. Then adjust the radius of the first inner formwork 3 or the second inner formwork 6 to separate the pouring part from the formwork. Use hoisting equipment to pull out the first inner formwork 3 or the second inner formwork 6. Finally, loosen the fixing bolts on the outside of the mold and dismantle the mold. After demolding, the pouring parts of the cylindrical section and the hemispherical end cap need to be properly cured to ensure that the concrete strength continues to increase in the later stage.

[0046] Step 4: Arrange the measuring points and straighten the lead wires. Strain gauges and pressure sensors are arranged on the inner surface of the cast-in-place component according to a preset pattern after curing. The strain gauges and pressure sensors are bonded to the inner surface of the cast-in-place component with epoxy resin adhesive and waterproofed. The leads of the strain gauges and pressure sensors are led out through the pre-embedded wire guide. After the cast-in-place component has cured, resistance strain gauges are attached to monitor deformation under hydrostatic pressure, while the hydrostatic pressure is monitored in real time using a pressure sensor. The strain gauges are placed on the inner surface of the cylindrical section of the cast-in-place component. In one embodiment of the invention, the strain gauges include circumferential and longitudinal strain gauges. Two to four rings of circumferential strain gauges are evenly arranged along the axial direction of the cylindrical section, with four circumferential strain gauges evenly arranged in each ring. The circumferential strain gauges are used to record the radial contraction and expansion behavior of the deep-water pressure hull. Four rows of longitudinal strain gauges are evenly arranged along the circumference of the cylindrical section. The line connecting two adjacent longitudinal strain gauges in the same row passes through the center point of the arc between two adjacent circumferential strain gauges and is collinear with a straight line parallel to the axis of the cylindrical section. The distance between two longitudinal strain gauges is equal to the distance between two circumferential strain gauges. That is, the line connecting two adjacent longitudinal strain gauges and the arc between two adjacent circumferential strain gauges are perpendicular to each other and bisect each other. Longitudinal strain gauges located at the same height should be arranged on the same cylindrical surface (i.e., the same horizontal profile) to ensure data comparability and spatial uniformity. This arrangement of strain gauges enables multi-directional, distributed strain monitoring of the vessel, providing accurate in-situ data support for analyzing its mechanical response, failure mode, and pressure-holding mechanism under hydrostatic pressure. Several pressure sensors are evenly distributed on the surface of the cast component according to its size and precision requirements.

[0047] Before attaching the strain gauge and pressure sensor, sand the mounting areas of the cylindrical section and hemispherical end cap with sandpaper to ensure a smooth and flat surface. After removing dust, clean with anhydrous ethanol or acetone to remove oil and impurities. Then, apply epoxy resin adhesive to the cleaned surface and attach the strain gauge smoothly, ensuring no air bubbles and a tight fit. After attachment, allow it to stand for a certain period of time until the adhesive is fully cured, avoiding disturbance to the strain gauge during this period. Waterproof the strain gauge and pressure sensor with waterproof material to prevent water seepage from affecting monitoring.

[0048] After the strain gauges and pressure sensors are attached, all leads are straightened out. The leads are led out to the external strain gauge through a wire guide. This wire guide can also serve as a water inlet and outlet, reducing the risk of explosion during subsequent high-pressure tests.

[0049] Step 5, assemble and seal. The demolded cylindrical section and hemispherical end cap are assembled to form a deep-water pressure-resistant shell.

[0050] Before assembly, strain gauges must be glued and waterproofed. Then, a waterproof coating primarily composed of epoxy resin is applied to the outer, joint, and inner surfaces of the cast component. The coating is applied using a combination of roller and brush to ensure waterproofing. The joint surfaces are then treated: first, sand them smooth, then use a blower to remove dust from the anchoring holes and joint surfaces. Anchoring adhesive is injected into the anchoring holes, and a thick layer of grout is applied to the joint surfaces and misalignments. Before application, sealant tape is wrapped around the top and bottom of the adhesive surfaces. The tape is removed after the grout has slightly cured, ensuring neat edges. An epoxy resin layer is then applied and injected. The cylindrical section and hemispherical end cap are then assembled. The assembly interval should not be too short to prevent damage to the incompletely cured adhesive layer. After the grout has completely solidified, the deep-water pressure-resistant shell is assembled and sealed.

[0051] Step 6, Quality Inspection The deep-water pressure hull is subjected to visual inspection, water pressure sealing test and strength verification.

[0052] After assembly, visual inspection confirmed that the deep-water pressure hull was structurally intact, free of cracks and deformation. Water was then injected into the deep-water pressure hull using a wire drill, and the water pressure was used to verify the hull's airtightness. Simultaneously, strength tests were conducted using synchronously cast cubic specimens to confirm that the concrete compressive strength met the requirements and that the quality of the deep-water pressure hull met the design requirements.

[0053] This deep-water pressure hull is suitable for concrete deep-water pressure-resistant structures in deep-sea environments with high permeability, strong corrosion, and high pressure. The above-mentioned casting method can be applied to the construction of deep-sea pressure-resistant facilities such as deep-sea exploration equipment carriers, pressure-resistant structures of deep-sea resource development platforms, and underwater nuclear wastewater storage containers.

[0054] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: 1. Through a four-factor multi-level orthogonal experiment, the optimal mix proportion of concrete with high compressive strength was selected, which solved the problems of unstable concrete performance and insufficient strength in existing technologies, and provided a reliable material basis for deep-water pressure hulls.

[0055] 2. A composite reinforcement cage (first reinforcement cage 2 and second reinforcement cage 5) is adopted, which combines ordinary steel bars and carbon fiber mesh for synergistic binding. This not only improves the structural crack resistance of the deep-water pressure hull, but also enhances its corrosion resistance, avoids cracking, and solves the defects of the existing single reinforcement structure.

[0056] 3. Solve the problem of casting large-volume thin-walled concrete shells, simultaneously cast cubic strength specimens to verify quality in real time, and cast concrete in layers and vibrate to ensure concrete density (significantly reduce porosity).

[0057] 4. Adopt a stepped steam curing system to control the temperature difference between the inside and outside of the concrete and avoid thermal stress cracks; determine the demolding strength to protect the integrity of the deep-water pressure shell.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A deep-water pressure hull casting apparatus, the deep-water pressure hull comprising a cylindrical section and two hemispherical end caps respectively disposed at both ends of the cylindrical section, characterized in that, The casting device includes two molds, namely a first mold and a second mold. The first mold is used to cast the cylindrical section, and the second mold is used to cast the hemispherical end cap. The first mold includes a first outer template, a first reinforcing cage, and a first inner template. The first reinforcing cage is located between the first outer template and the first inner template. The hemispherical end cap includes a second outer template, a second reinforcing cage, and a second inner template, wherein the second reinforcing cage is located between the second outer template and the second inner template. Ultra-high performance concrete is poured between the first outer formwork and the first inner formwork, and ultra-high performance concrete is poured between the second outer formwork and the second inner formwork. After the two second molds and the first mold are spliced ​​and disassembled, the ultra-high performance concrete, the first steel cage and the second steel cage together form the deep-water pressure-resistant shell.

2. The deep-water pressure-resistant hull casting device according to claim 1, characterized in that, The casting device also includes a base and a flange. The base is made of steel plate. The upper surface of the base is provided with a groove. The groove is annular. The width of the groove matches the thickness of the first inner template. A sponge strip is pasted inside the groove. The first inner template is a cylinder, which is spliced ​​from multiple arc-shaped cold-rolled steel plates. The lower end of the first inner template can be inserted into the groove on the base. The upper end of the first inner template is provided with a cylinder mold fixing fixture, which consists of an annular positioning ring and two positioning plates. The two positioning plates are arranged in a cross shape inside the positioning ring. Multiple top supports extending towards the center of the positioning ring are provided on the inner wall of the positioning ring. The inner diameter of the positioning ring is the same as the inner diameter of the first outer template, and the multiple top supports are symmetrically distributed. The first reinforcing cage includes multiple longitudinal bars, multiple stirrups, and a carbon fiber mesh. The base and the cylindrical mold fixing fixture are each provided with several positioning holes. The longitudinal bars are arranged vertically, and the multiple longitudinal bars are evenly distributed around the first inner mold. The two ends of the longitudinal bars are respectively located in the positioning holes on the positioning ring and the base. The carbon fiber mesh is wrapped around the outside of the longitudinal bars, and the stirrups are sleeved on the outside of the carbon fiber mesh. The multiple stirrups are evenly distributed along the height direction of the carbon fiber mesh. The intersection of the longitudinal bars, the stirrups, and the carbon fiber mesh is used for binding and fixing to form the first reinforcing cage. The first outer template is a cylinder, and it is composed of multiple arc-shaped cold-rolled steel plates spliced ​​together. The joints of the multiple arc-shaped cold-rolled steel plates are fastened by connecting ear plates and bolts. The diameter of the first outer template is larger than the diameter of the first inner template. The flange is mounted on the base, and the inner diameter of the flange is the same as the outer diameter of the groove. The lower end of the first outer template and the bottom of the first inner template are connected by the flange. The carbon fiber mesh has a bidirectional structure, and the material of the carbon fiber mesh is a carbon fiber reinforced composite material of carbon fiber filaments and resin matrix; A steel sleeve is welded at the joint between the second mold and the first mold as a reserved hole for rebar installation.

3. The deep-water pressure-resistant shell casting device according to claim 1, characterized in that, The second outer template is hemispherical and is made of multiple cold-rolled steel plates in the shape of spherical petals. The second outer template is set on a fixed support, and the shape of the upper surface of the fixed support is adapted to the outer surface of the second outer template. The second reinforcing cage is made of reinforcing bars and carbon fiber mesh. The second reinforcing cage is hemispherical. The outer diameter of the second reinforcing cage is smaller than the inner diameter of the second outer template, and the inner diameter of the second reinforcing cage is larger than the outer diameter of the second inner template. The second inner template is hemispherical and is made up of multiple transparent acrylic sheets in the shape of spherical petals. The second outer template and the second inner template are also connected by a ball mold fixing fixture; The ball mold fixing fixture includes a fixing plate and a fixing frame. The fixing plate has a circular cross-section and covers the bottom surface of the hemispherical end cap. The fixing plate is connected to both the second inner template and the second outer template. Multiple fan-shaped grouting ports are evenly arranged on the fixing plate along the circumference. Ultra-high performance concrete can be poured between the second outer template and the second inner template through the grouting ports. A cover plate is provided at each grouting port, and the shape of the cover plate is adapted to the shape of the grouting port. The bottom surface of the second steel cage is welded with a steel sleeve as a reserved hole for rebar installation.

4. A method for casting a deep-water pressure hull, using the deep-water pressure hull casting apparatus according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Fabricate a deep-water pressure hull casting device. The first mold is made using the first outer formwork, the first inner formwork, and the first reinforcing cage; the second mold is made using the second outer formwork, the second inner formwork, and the second reinforcing cage. Step 2: Mixing and pouring ultra-high performance concrete. Ultra-high performance concrete was mixed according to the optimized mix proportion and poured into the first and second molds in layers. After each layer was poured, it was vibrated to ensure that the concrete was dense. Step 3, steam curing and demolding. After the concrete has initially set, the mold is subjected to stepped steam curing. Once the concrete reaches the designed demolding strength, the mold is removed and subsequent curing is carried out to complete the casting of the cylindrical section and the hemispherical end cap. Step 4: Arrange the measuring points and straighten the lead wires. Strain gauges and pressure sensors are arranged on the inner surface of the cured casting according to a preset pattern, and the strain gauges and pressure sensors are waterproofed. The leads of the strain gauges are led out through the pre-embedded wire guide. Step 5, assemble and seal. The demolded cylindrical section and hemispherical end cap are assembled to form a deep-water pressure-resistant shell; Step 6, Quality Inspection The deep-water pressure hull is subjected to visual inspection, water pressure sealing test and strength verification.

5. The casting method for deep-water pressure hull according to claim 4, characterized in that, Step 1 specifically includes: Step 11, mold pretreatment, An oil-based release agent is brushed onto the surfaces of the first outer template, the first inner template, the second outer template, and the second inner template. Step 12, close the cylindrical section mold. A base is constructed using steel plates. The top surface of the base is calibrated with a level. The base is then fixed to the working surface using expansion bolts. A groove with a width matching the thickness of the first inner template is pre-drilled on the base. Thick sponge strips are pasted into the groove, and the flange is placed on the base. The first inner template is inserted into the groove of the base, with its lower edge completely embedded in the sponge strip. The first template and the flange are then welded together. A cylindrical mold fixing fixture is installed at the upper end of the first inner template. The longitudinal reinforcement bars are evenly arranged around the first inner template through the positioning holes on the base and the cylindrical mold fixing fixture. Carbon fiber mesh is wrapped around the outside of the longitudinal reinforcement bars. Finally, according to the stirrup spacing designed in the drawings, the stirrups are fitted onto the carbon fiber mesh. Ties are used to secure the carbon fiber mesh in overlapping areas and at the intersections of the carbon fiber mesh, longitudinal reinforcement bars, and stirrups to form the first reinforcing cage. The first outer template is then installed. Tie bolts are placed between the back ribs of the first outer template and the inner template. The bolt holes are precisely machined using a hole saw. The tie bolts are tightened, and the flatness of the template surface is checked. Step 13, close the hemispherical end cap mold. First, the second outer formwork is fixed by a fixed bracket. The second outer formwork is made of prefabricated spherical cold-rolled steel plates spliced ​​together. The second reinforcing cage is placed inside the second outer formwork. Then, the second inner formwork is installed. The second inner formwork is made of transparent acrylic sheets spliced ​​together. The joints are sealed with special glue and reinforced with fiberglass cloth. The formwork is hoisted using a spherical formwork fixing fixture. After being lowered into place, the second inner formwork is connected and fixed to the second outer formwork using the spherical formwork fixing fixture. Step 14, Mold Measurement The dimensions of the first and second molds after mold assembly are measured to ensure that the mold dimensions meet the design standards. At the same time, the molds are checked to ensure that they are free from deformation and correctly assembled. The specimen model and casting date are recorded on the outer surface of the molds.

6. The casting method for deep-water pressure hull according to claim 4, characterized in that, In step 2, the mix proportion is optimized through a four-factor multi-level orthogonal test to make the compressive strength of ultra-high performance concrete greater than 120 MPa. Ultra-high performance concrete is poured in layers into the first and second molds. After each layer is poured, it is vibrated and then allowed to stand still. During the stand-up period, grout is continuously added. During the stand-up period, the concrete must be protected from freezing. Steam preheating is required before the temperature drops to 0℃. At the same time, cubic concrete specimens are poured simultaneously with each mold. These specimens are used for subsequent strength testing in conjunction with the implosion test to verify whether the compressive strength of the concrete meets the standard. When pouring concrete in layers, pour the concrete into the mold in layers of 5cm-10cm thickness each time. The thickness of each layer is 5cm-10cm. Fill the entire first and second steel cages layer by layer to ensure that the first and second steel cages are completely embedded in the concrete.

7. The casting method for deep-water pressure hull according to claim 4, characterized in that, In step 3, the stepped steam curing includes three stages: heating at a certain rate, maintaining a constant temperature, and cooling down steadily. The specific parameters for stepped steam curing are as follows: during the heating stage, the heating rate is controlled, and the temperature of the curing chamber is slowly increased from room temperature to the target temperature. The heating rate is controlled within 10℃ / h until the set temperature of 75℃±5℃ is reached. During the constant temperature stage, the temperature is kept constant and the relative humidity is above 95%. Steam supply is used to ensure that the concrete surface is moist to prevent dehydration, shrinkage and cracking. After constant temperature steam curing at the target temperature for more than 8 hours, the cooling stage begins. During the cooling phase, the temperature is gradually and steadily reduced to near room temperature, with the cooling rate controlled to no more than 10°C per hour. Before demolding, it is necessary to confirm that the concrete has reached the demolding strength of the design strength. When demolding, first grind the surface of the cast part to remove excess concrete and ensure flatness. Then adjust the radius of the first or second inner formwork to separate the cast part from the formwork. Use hoisting equipment to pull out the first or second inner formwork. Finally, loosen the fixing bolts on the outside of the mold and disassemble the mold. After demolding, the cast parts of the cylindrical section and hemispherical end cap need to be properly cured to ensure that the concrete strength continues to increase in the later stage.

8. The casting method for deep-water pressure hull according to claim 4, characterized in that, In step 4, strain gauges and pressure sensors are arranged on the inner surface of the cured casting according to a preset pattern. The strain gauges and pressure sensors are bonded to the inner surface of the casting using epoxy resin adhesive and waterproofed. The leads of the strain gauges and pressure sensors are led out through pre-embedded wire guides. Strain gauges are arranged on the inner surface of the cylindrical section casting. The strain gauges include circumferential strain gauges and longitudinal strain gauges. The circumferential strain gauges are evenly arranged in 2-4 rings along the axial direction of the cylindrical section, with 4 circumferential strain gauges evenly arranged in each ring. The circumferential strain gauges are used to record the radial contraction and expansion behavior of the deep-water pressure hull. Two longitudinal strain gauges are arranged around two adjacent circumferential strain gauges. The longitudinal strain gauges are used to monitor the axial strain state. The leads of the strain gauges and pressure sensors are led out to the external strain gauge through a wire guide. The wire guide also serves as the inlet and outlet of the water.

9. The casting method for a deep-water pressure hull according to claim 4, characterized in that, In step 5, a waterproof coating with epoxy resin as the main component is applied to the outer surface, splicing surface and inner surface of the casting. The splicing surface is treated, and the anchoring adhesive is injected into the anchoring holes. A thick layer of grout is applied to the splicing surface, followed by an epoxy resin layer and injection of adhesive. The cylindrical section and hemispherical end cap are assembled. After the grout has completely solidified, the assembly and sealing of the deep-water pressure-resistant shell is completed.

10. The casting method for a deep-water pressure hull according to claim 4, characterized in that, In step 6, after assembly, the structure of the deep-water pressure hull is confirmed to be intact, without cracks or deformation through visual inspection. Water is injected into the deep-water pressure hull using a wire drill, and the water pressure is used to verify the sealing performance of the deep-water pressure hull. At the same time, a strength test is carried out using a cube specimen that is poured simultaneously to confirm that the compressive strength of the concrete meets the requirements and that the quality of the deep-water pressure hull meets the design requirements.

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