Anti-cracking formwork system for anti-radiation concrete wall and non-through-seam construction method of anti-cracking formwork system

Abstract

The invention discloses a radiation-proof concrete wall anti-cracking formwork system and a non-through-seam construction method, and belongs to the field of civil engineering. After the wall body is segmented, double-pump symmetrical layered pouring is performed; double staggered-platform rabbets are arranged between the sections to form nonlinear occlusion; a hollow partition component with a filling cavity is arranged in the path of the opposite-pull screw, and the radiation straight-through is cut off after concrete filling; the low-hydration-heat gel system is matched with real-time temperature measurement and adjustable heat preservation, and the temperature difference between the inside and the outside is smaller than or equal to 20 DEG C. The hollow partition component can be expanded into a stepped density inclined plane multi-layer prefabricated block, and the ray disturbing effect is improved. The ultra-thick anti-radiation wall has been applied to a wall body of a flaw detection room with the thickness of 2.65-3.10 m, realizes zero-through-joint and zero-penetrating-crack, meets the requirements of zero-through-joint, zero-leakage and zero-penetrating-crack, and is suitable for ultra-thick anti-radiation structures of nuclear facilities, proton treatment centers and the like.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to a crack-resistant formwork system for ultra-thick radiation-proof concrete walls and a seamless construction method thereof, which is applicable to the construction of building structures with extremely high requirements for radiation protection performance, such as nuclear power plants, flaw detection rooms, and proton therapy centers. Background Technology

[0002] With the development of nuclear industry, medical radiotherapy, particle accelerators, and other fields, the demand for radiation-shielding building structures is increasing. Radiation-shielding concrete walls, as a key structure for shielding radiation, are typically over 2 meters thick, and in some critical areas even exceed 3 meters. These ultra-thick concrete walls not only require excellent radiation shielding performance but also must meet stringent standards of being crack-free, seamless, and leak-free to prevent radiation leakage and ensure the safety of personnel and equipment.

[0003] However, in actual construction, ultra-thick radiation-proof concrete walls face the following technical challenges: 1. Crack control is difficult Large-volume concrete is prone to temperature stress during hydration. If not properly controlled, it is very easy for temperature difference cracks or shrinkage cracks to occur, affecting structural integrity and radiation protection performance.

[0004] 2. High risk of open seams Traditional construction joint treatments are mostly planar joints, which easily form through gaps, becoming channels for radiation leakage and failing to meet the sealing requirements of radiation protection structures.

[0005] 3. Poor adaptability of template system Conventional formwork systems are not optimized for ultra-thick walls, resulting in problems such as unstable reinforcement, loose joints, and rough interface treatment, leading to poor concrete surface quality and defects at the joints.

[0006] 4. The construction joint has a simple structure. In existing technologies, construction joints mostly use straight flat joints or simple tongue and groove joints, lacking multi-layer anti-penetration structural design, making it difficult to effectively block the extension of horizontal or vertical cracks in ultra-thick walls.

[0007] 5. The tie rod forms a potential channel. Traditional tie rods penetrate the wall, and without special treatment, potential crack channels can easily form along the rod path, increasing the risk of radiation leakage.

[0008] In summary, current technologies have not yet developed a comprehensive, integrated solution for preventing cracks and through-joint joints in the construction of ultra-thick radiation-shielding concrete walls. Therefore, there is an urgent need for a novel crack-resistant formwork system and a seamless construction method to address these technical challenges and improve the overall safety and durability of radiation-shielding structures. Summary of the Invention

[0009] This invention aims to solve the problems of through-joints and harmful cracks that easily occur during the construction of existing ultra-thick radiation-shielding concrete walls, preventing radiation leakage due to structural cracks and ensuring the overall airtightness, structural safety, and radiation protection performance of the wall. Simultaneously, it addresses the shortcomings of traditional formwork systems in ultra-thick wall construction, such as loose joints, unstable reinforcement, and improper treatment of construction joints, providing a systematic construction method that is structurally sound, convenient to construct, and has controllable quality.

[0010] To achieve the above objectives, the present invention is implemented as follows: A crack-resistant formwork system for radiation-shielding concrete walls and a seamless construction method thereof, comprising: The segmented continuous casting module is used to divide the ultra-thick wall vertically into several sections that can be constructed simultaneously, and to complete the concrete supply in a layered, cyclical and uninterrupted manner, thereby eliminating cold joints. Interface anti-penetration construction module, set at the horizontal / vertical interface of adjacent construction sections, is used to form at least one non-linear interlocking channel to block the direct path of radiation and cracks; The template-screw integrated sealing module includes a reusable positioning tongue and groove unit at the top of the template and a tie screw unit with a filling cavity in the middle section, which is used to transmit the template fixing force between sections and at the same time cut off the radial penetration of the screw channel; The hydration heat and shrinkage synergistic control module is used to dynamically adjust the internal temperature drop rate of concrete through cementitious material system optimization, real-time temperature difference monitoring and variable angle insulation coverage, so that the temperature difference between the inside and outside surfaces is always below the cracking threshold. The above modules work together to ensure that the wall has no through cracks or straight channels after curing, thus meeting the sealing requirements of the radiation protection structure.

[0011] Furthermore, a "double-staggered tongue-and-groove unit" is incorporated into the anti-penetration interface structure module, creating a stepped interlocking structure along the wall thickness direction. At least one step exhibits a three-stage variation relative to the wall surface: "recessed-protruding-recessed." This increases the tortuosity of the ray propagation path, significantly improving shielding redundancy. Simultaneously, the stepped interlocking structure releases shrinkage stress, reducing the risk of interface cracking.

[0012] Based on any of the aforementioned solutions, in the template-screw integrated sealing module, the "filling cavity" is a "hollow partition component" on the tie rod path. This component allows concrete slurry to enter and, after hardening, forms a "discontinuous medium layer" together with the screw, thereby cutting off the straight-line propagation of radiation. This overcomes the defect of traditional through-bolts easily forming radiation channels, while utilizing the shielding properties of concrete itself to replace part of the metal shielding, balancing cost and effectiveness.

[0013] Based on the aforementioned hollow partition component, this component is further configured to consist of "at least two layers of prefabricated blocks of different densities and / or different materials stacked sequentially along the direction of ray incidence" to disrupt and attenuate the ray propagation path and penetration rate. Through the combination of density and material gradients, the ray scattering and absorption efficiency can be significantly improved without increasing the component thickness, reducing the dependence on the overall wall thickness.

[0014] Based on the aforementioned gradient precast blocks, the precast blocks are further embedded into the "central opening of a flat steel plate," and this flat steel plate is welded to two coaxially arranged tie rod bodies to form an "integrated load-bearing and partition component." In this way, the original tensile function of the tie rods is preserved, and the "shielding unit" and "load-bearing unit" are integrated in the same position, avoiding additional space occupation within the wall and improving construction efficiency.

[0015] Based on the aforementioned "Crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method," the following further features are added to the "Hydration heat and shrinkage synergistic control module": Low hydration heat gelling system – reducing temperature rise through mineral admixtures and crack-resistant additives; Adjustable heat dissipation / insulation device – Based on measured temperature data, selectively exposes or covers the template surface to control the cooling gradient in a programmed manner; Induced joint release unit – used to pre-set closable energy-dissipating joints in areas of wall stress concentration, guiding the orderly release of shrinkage energy without forming harmful cracks.

[0016] The above three sub-features together constitute an active-passive temperature control-crack resistance system, which can adapt to the construction of large-volume concrete with different seasons and different cross-sectional thicknesses.

[0017] Furthermore, based on the aforementioned basic scheme, the "segmented continuous casting module" adopts a "dual-pump symmetrical placement + internal vibration synchronous follow" process to ensure that each layer of concrete is covered by the upper layer of concrete before initial setting, thereby "self-healing" potential cold joints. In this way, the risk of "cold joints" is moved forward to the casting stage and eliminated through technological means, reducing the reliance on subsequent grouting or surface repair.

[0018] Building upon the aforementioned double-staggered tongue-and-groove unit, a tongue-and-groove is further formed by "detachable formwork components and rebar positioning parts." The formwork components remain inside the wall after demolding, serving as the "alignment benchmark" for the next construction section, achieving "zero-gap connection" during formwork installation. This combines "structural shielding" with "formwork positioning function," reducing repetitive processing and improving construction accuracy and efficiency.

[0019] Through the aforementioned progressively advanced technical solutions, this invention provides system-level protection for the three core indicators of "crack prevention, through-crack prevention, and radiation penetration prevention": stepped tongue and groove joints and gradient precast blocks jointly extend the radiation path; hollow partition components cut off the screw channel; closed-loop temperature control and induced joint release actively suppress temperature-shrinkage cracks; and integrated formwork-tongue and groove-positioning improves construction accuracy. Each layer of additional features functions independently yet synergistically, ensuring that the ultra-thick radiation-proof concrete wall maintains high shielding performance and high integrity throughout its entire lifespan. Attached Figure Description

[0020] Figure 1 This is a diagram showing the vertical segmented pouring sequence of the wall in this invention.

[0021] Figure 2 This is a schematic diagram of the interface treatment at the construction joint location of new and old concrete in this invention.

[0022] Figure 3 This is a plan and cross-sectional view of the horizontal construction joint construction measures for concrete walls in this invention.

[0023] Figure 4 This is a detailed diagram of the tie rod construction in this invention. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0025] Example 1: A. This embodiment is located in the flaw detection room area of ​​a certain ship digital development support condition construction project. The main radiation protection structure has a planar dimension of 29.85 m × 27.55 m, a wall thickness of 2.65 m, 2.7 m, 2.75 m, and 3.1 m, and a top plate thickness of 2.1 m. The designed radiation source is a 6 MV linear accelerator, and the requirements are "zero through seams, zero leakage, and zero penetrating cracks".

[0026] B. Specific construction process of the four major modules Segmented continuous casting module ① Vertical segmentation: according to Figure 1 The entire wall is divided into six sections along its height, each with a net height of 2.8 m. This takes into account the elevation of the attached second-floor structure and the location of equipment openings, ensuring that the edge of the opening is ≥300 mm away from the construction joint.

[0027] ② Dual-pump symmetrical material distribution: Two 47 m truck-mounted pumps are arranged in each section, advancing obliquely from the far end to the pump position. Each layer is 500 mm thick. The vibrator has an action radius of 1.4 times the spacing (400-500 mm) with quincunx-shaped insertion points. Insert quickly and pull out slowly. The upper layer is re-vibrated to the lower layer by 50 mm to ensure self-healing between layers.

[0028] ③ Cold joint control: The upper layer of concrete must be covered before the lower layer initially sets. The initial setting time should be tested on site using a portable penetration resistance meter. If the interval due to equipment failure is longer than the initial setting time, it should be treated as a construction joint and a double tongue-and-groove joint should be made.

[0029] Interface anti-penetration construction module ① Double error in Taiwan-funded enterprises ( Figure 3 ): Two 400 mm (width) × 400 mm (height) wooden boxes are prefabricated in the middle of each wall section. The wooden boxes are made of 18 mm plywood, with φ10 mm holes drilled around them. φ8 steel bars are passed through and spot welded to the main reinforcement to prevent them from floating or shifting upwards.

[0030] ② Formation of staggered steps: The middle area is poured first, followed by the two sides. The middle concrete surface is 100 mm lower than the outer side. After demolding, a three-stage "concave-convex-concave" staircase is formed, with a step depth of 50 mm and a height difference of 100 mm. The ray propagation path is increased by more than 1.4 times.

[0031] ③ Template reference retention: The bottom plate of the wooden box is not removed during demolding and serves as the alignment reference for the next section of the template, achieving "zero gap connection" ( Figure 2 This helps prevent grout leakage at the joints.

[0032] Template-Screw Integrated Sealing Module ① Top edge strip ( Figure 2 ): Nail an 18 mm × 30 mm strip along the top edge of the template. Remove it after the concrete has set, leaving a small tongue and groove joint. The top M16 high-strength bolt is not removed 150 mm from the finished surface and is used directly as the bottom fixing point of the next section of the template.

[0033] ② Hollow partition component: A 100 mm × 50 mm × 3 mm steel plate box (with a 50 mm × 18 mm long hole in the center of the flat steel plate) is inserted into the middle section of the tie rod, and the following components are inserted sequentially along the incident direction of the rays inside the box: First layer: 2 mm tungsten-nickel alloy sheet, density 17 g / cm³ 3 ; Second layer: 5 mm boron-aluminum composite board, boron content 2.5%, density 2.7 g / cm³ 3 ; Third layer: 3 mm ordinary steel backing plate, density 7.85 g / cm³ 3 .

[0034] The steel plate box is fully welded to the two coaxial screw bodies on both sides, with a weld height of 3 mm. The box body is equipped with φ6 vent holes at the top and bottom to ensure that the concrete is filled densely and form a "discontinuous medium layer".

[0035] ③ Effect: Actual measurements show that this component has an additional attenuation rate of ≥12% for 6 MV X-rays and completely blocks the screw through the gap.

[0036] Hydration heat and contraction coordinated control module ① Mixing ratio (per m) 3 ): 320 kg of P·O42.5 cement, 40 kg of Grade II fly ash, 25 kg of S95 mineral powder, 8 kg of crack-resistant agent-V, 1.0% of polycarboxylate superplasticizer, water-cement ratio 0.38, slump 160±20 mm, air content ≤5%.

[0037] ② Temperature measurement points: Three measurement points along the wall thickness surface - center - back, automatic data collection once every 10 minutes; Control indicators: Tmax≤60 ℃, temperature difference between inside and outside ≤20 ℃, cooling rate≤2 ℃ / d.

[0038] ③ Curing: Immediately after finishing, cover with 0.2 mm plastic film + two layers of cotton felt. The insulation layer is removed in layers after the concrete strength reaches 30% of the design value and the temperature difference is less than 20 ℃ for 48 consecutive hours. The total curing period is 14 days.

[0039] C. Extended Implementation In another embodiment, the prefabricated blocks of the hollow partition component can be replaced with a "stepped density" structure: the density along the ray direction increases from 2.2 g / cm³. 3 →7.8 g / cm 3 →17 g / cm 3 The scattering probability is increased by increasing the angle between the interface of each layer and the incident angle of the ray at 30-45°. This further extends the path and increases the scattering probability. This solution also embeds an opening in the planar steel plate and welds it coaxially with the two screw sections, replacing the parallel stacked structure of this embodiment.

[0040] D. Test results Twenty-eight days after wall completion, radiographic testing was conducted according to GBZ / T 144. No continuous cracks longer than 50 mm were found, and there were no penetrating channels. Infrared thermography showed a maximum surface-to-interior temperature difference of 18 °C. The concrete core sample strength was 58 MPa, its impermeability was >P12, and its chloride ion diffusion coefficient was <500 °C. This meets the design requirements of "zero through cracks, zero leakage, and zero penetrating cracks."

[0041] The above modules can be moved as a whole to ultra-thick radiation protection structures such as proton therapy rooms and nuclear facility shielding walls. Only the wall thickness, segment height, and number of hollow partition components need to be adjusted according to the shielding level, without changing the core process logic.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A crack-resistant formwork system for radiation-shielding concrete walls and a seamless construction method thereof, characterized in that, include: The segmented continuous casting module is used to divide the ultra-thick wall vertically into several sections that can be constructed simultaneously, and to complete the concrete supply in a layered, cyclical and uninterrupted manner, thereby eliminating cold joints. Interface anti-penetration construction module, set at the horizontal / vertical interface of adjacent construction sections, is used to form at least one non-linear interlocking channel to block the direct path of radiation and cracks; The template-screw integrated sealing module includes a reusable positioning tongue and groove unit at the top of the template and a tie screw unit with a filling cavity in the middle section, which is used to transmit the template fixing force between sections and at the same time cut off the radial penetration of the screw channel; The hydration heat and shrinkage synergistic control module is used to dynamically adjust the internal temperature drop rate of concrete through cementitious material system optimization, real-time temperature difference monitoring and variable angle insulation coverage, so that the temperature difference between the inside and outside is always below the cracking threshold. The above modules work together to ensure that the wall has no through cracks or straight channels after curing, thus meeting the sealing requirements of the radiation protection structure.

2. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 1, characterized in that, The interface anti-penetration construction module includes a double staggered tongue and groove unit. The tongue and groove unit forms a stepped interlocking in the wall thickness direction, and at least one step has a three-stage change relative to the wall surface: concave-convex-recessed.

3. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 1 or 2, characterized in that, The filling cavity in the template-screw integrated sealing module is a hollow partition component on the path of the tie screw. The component allows concrete slurry to enter and, after hardening, forms a discontinuous medium layer with the screw, thereby cutting off the linear propagation of radiation.

4. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 3, characterized in that, The hollow partition component consists of at least two layers of prefabricated blocks of different densities and / or materials stacked sequentially along the direction of ray incidence, in order to disrupt and attenuate the ray propagation path and penetration rate.

5. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 4, characterized in that, The precast block is embedded in the central opening of the flat steel plate, and the flat steel plate is welded to two coaxially arranged tie rod bodies to form an integrated load-bearing and partition component.

6. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 1, characterized in that, The hydration heat and contraction coordinated control module includes: The low hydration heat cementitious system reduces temperature rise through mineral admixtures and crack-resistant additives; An adjustable heat dissipation / insulation device selectively exposes or covers the template surface based on measured temperature data, thereby controlling the cooling gradient through a program. The induction joint release unit is used to pre-set a closable energy-dissipating joint in the stress concentration area of ​​the wall, guiding the orderly release of shrinkage energy without forming harmful cracks.

7. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 1, characterized in that, The segmented continuous casting module adopts a dual-pump symmetrical material distribution + internal vibration synchronous follow process to ensure that each layer of concrete is covered by the upper layer of concrete before initial setting, thereby self-healing potential cold joints.

8. The crack-resistant formwork system for radiation-shielding concrete walls and its seamless construction method according to claim 2, characterized in that, The double staggered tongue and groove unit is formed by a detachable template assembly and a steel reinforcement positioning component. After the template is removed, it is left inside the wall to serve as the alignment reference for the next construction section, thus achieving zero-gap connection of the template installation.

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