Anti-radiation system construction method for proton therapy building

Abstract

The invention discloses an anti-radiation system construction method for a proton therapy building, and the method comprises a large-volume heavy concrete construction control method and a radiation protection wall construction control method, and the large-volume heavy concrete construction control method comprises the following steps: preparing heavy concrete; comprising the steps of concrete raw material control, concrete mix proportion design, concrete trial preparation verification and concrete durability test. Concrete pouring, wherein bottom plate concrete pouring and wall and top plate concrete pouring are included; concrete temperature measurement is carried out to reflect the highest temperature rise in the concrete pouring body, the temperature difference between the inner surface and the outer surface, the cooling rate and the environment temperature; curing the concrete; the radiation protection wall construction control method comprises the steps that a tongue-and-groove-shaped construction joint and a pre-embedded curve or broken line type sleeve are adopted to hinder linear propagation of radiation; temperature control of mass concrete is taken into consideration, radiation leakage is prevented while construction convenience and concrete uniformity are guaranteed, and the radiation protection effect of the ultra-thick concrete structure is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of building technology, and in particular to a construction method of a radiation protection system for a proton therapy building. Background Art

[0002] With the rapid development of cancer treatment technology research and development in countries around the world, proton therapy for tumors has become a new generation of more effective radiotherapy technology due to its deep cutoff effect brought by the proton Bragg peak effect and more precise width direction control. Clinical results show that compared with other radiotherapy methods, especially for tumors surrounded by important tissues and organs, proton therapy shows great advantages: high accuracy, high cure rate, and few side effects. Proton therapy devices are the mainstream equipment for tumor radiotherapy in the world. At present, many places in my country are building / preparing to build proton therapy centers.

[0003] Proton therapy equipment has extremely high requirements for construction technology and radiation safety. The construction of a proton center needs to consider the radiation safety issues caused by the proton therapy equipment. Since the concrete pouring volume is large and cannot be completed in one go, in order to prevent radiation leakage, how to leave construction joints and avoid linear through-holes in the structure has become a major difficulty in proton building engineering. Therefore, this application proposes a radiation protection system construction method for proton therapy buildings to solve the above problems. Summary of the invention

[0004] In order to solve the above problems, the present application provides a construction method of a radiation protection system for a proton therapy building, which takes into account the temperature control of large-volume concrete, reduces the temperature difference between the inside and outside, avoids cracks, prevents radiation leakage while ensuring the convenience of construction and the uniformity of concrete, and ensures the radiation protection effect of ultra-thick concrete structures. The technical solution is as follows:

[0005] The present application provides a construction method for a radiation protection system for a proton therapy building, including a large-volume heavy concrete construction control method and a radiation protection wall construction control method. The large-volume heavy concrete construction control method includes the following steps: preparing heavy concrete, including concrete raw material control, concrete mix design, concrete trial mixing verification and concrete durability test; concrete pouring, including bottom plate concrete pouring and wall and top plate concrete pouring; concrete temperature measurement to reflect the maximum temperature rise, inside and outside temperature difference, cooling rate and ambient temperature in the concrete pouring body; concrete curing; the radiation protection wall construction control method includes using a "tongue-in-groove" construction joint and a pre-buried curve or broken line casing to hinder the linear propagation of radiation.

[0006] For example, in the radiation protection system construction method for a proton therapy building provided in one embodiment, the control of concrete raw materials in the large-volume heavy concrete construction control method includes the control of cement, fly ash, mineral powder, magnetite coarse aggregate, iron ore fine aggregate, ordinary fine aggregate, admixtures, special anti-cracking agents, radiation protection additives and mixing water.

[0007] For example, in the construction method of the radiation protection system for a proton therapy building provided in one embodiment, in the control of the concrete raw materials: the cement specific surface area is 300-350 m2 / kg, the alkali content is less than 0.60%, the C3A content is less than 8%, and the C3S content is less than 55%, so as to control the hydration heat and temperature rise inside the concrete; the fly ash water demand ratio does not exceed 100%, and the fluidity ratio is ≥100%; the magnetite coarse aggregate is mixed with secondary or multi-graded aggregates to meet the particle grading requirements; the fineness modulus and particle grading of the iron ore fine aggregate meet the requirements of the medium sand in the medium grading zone II of JGJ 52, the stone powder content and the organic matter content meet the requirements of JGJ 52, and the apparent density is ≥3700 kg / m 3 , mud content ≤0.5%, firmness ≤8%, chloride ion content ≤0.02%, sulfide and sulfate content calculated as SO3 ≤0.5%, and radioactivity complies with the provisions of GB6566; ordinary fine aggregate uses clean medium and coarse sand with low water absorption and small porosity, the fineness modulus is 2.4-2.8, and the particle grading meets the requirements of Zone II, the mud content in the sand ≤3.0%, and the mud content ≤1.0%; the admixture has high solid content, high water reduction rate, high fluidity and high bond stability; the radiation protection additive contains boron and chromium elements, the water content of the radiation protection additive is ≤10%, the free calcium oxide content is ≤3.0%, the chloride ion content is ≤0.02%, and the sulfur trioxide content is ≤4.0%.

[0008] For example, in the construction method of the radiation protection system for proton therapy building provided in one embodiment, the concrete mix design in the large-volume heavy concrete construction control method includes the following steps: (1) on the basis of meeting the strength and workability of concrete, by adding mineral admixtures and optimizing the reasonable combination, reducing the amount of cement and cementitious materials, determining the total amount of cement materials according to the optimal principle, reducing the heat release of hydration, and facilitating the control of shrinkage and cracking risks of concrete; (2) reasonably controlling the water-cement ratio and the maximum water consumption of concrete, while ensuring the strength, reducing the adverse effects caused by self-shrinkage; (3) further adding an appropriate amount of high-efficiency anti-cracking agent on the basis of the above steps, improving the crack resistance through the coordinated regulation of hydration rate and shrinkage history, and inhibiting concrete cracking; (4) using a water-reducing polycarboxylic acid high-performance water-reducing agent with a 28d shrinkage ratio of ≤100%, while reducing the water consumption per cubic meter of concrete, without increasing the shrinkage of concrete, improving the workability of concrete, and at the same time compacting the concrete to improve the mechanical properties and durability; in addition, appropriately entraining air in the concrete to improve the homogeneity, pumping performance and ultimate tensile value of the concrete, and improve the workability of the concrete.

[0009] For example, in the radiation protection system construction method for a proton therapy building provided in one embodiment, the concrete trial mixing verification in the large-volume heavy concrete construction control method includes: on the basis of meeting the working performance, mechanical properties, durability and crack resistance of the concrete, the concrete mix ratio is determined according to multiple trial mixing verifications, and the mix ratio uses magnetite ore and magnetite sand as coarse aggregate, which is mainly used for proton area construction.

[0010] For example, in the radiation protection system construction method for a proton therapy building provided in one embodiment, the concrete durability test in the large-volume heavy concrete construction control method includes: conducting a frost resistance test, a permeability test, a non-contact shrinkage test, a chloride ion penetration test, and an early crack resistance test on the heavy concrete, so that various indicators meet the performance requirements of heavy concrete.

[0011] For example, in the construction method of the radiation protection system for a proton therapy building provided in an embodiment, the bottom plate concrete pouring method in the large-volume heavy concrete construction control method is: the bottom plate concrete pouring adopts an oblique advancement and layered pouring method, and the pouring thickness of each layer is 400-600 mm, and the construction is organized in an oblique advancement manner from the far end to the pump direction; the concrete is vibrated using an inserted vibrator, and the vibrating rod is required to be inserted quickly and pulled out slowly to ensure that the vibrating rod is inserted to a depth and the concrete has sufficient time to be vibrated and compacted. The spacing of the vibration points is 1.5 times the effective radius of the vibrating rod, generally controlled at 400-500 mm, and the vibration time is controlled to be based on the concrete no longer sinking and no bubbles are generated. The vibration should be carried out evenly and orderly with the progress of material feeding; multiple vibrations are required in places with dense steel bars to ensure that the concrete is densely packed, and the vibration time cannot be too long at one time to prevent local concrete from over-vibration and segregation; in areas where embedded parts and steel bars are staggered and dense, thick steel bars are required to be used to assist in manual insertion and compaction.

[0012] For example, in the construction method of the radiation protection system for a proton therapy building provided in an embodiment, the method for pouring wall and top slab concrete in the large-volume heavy concrete construction control method is as follows: the slump of the wall and top slab concrete poured into the mold is controlled to be 160-200 mm, and the air content is controlled to be ≤5%; before pouring the upper side wall and top slab concrete, the upper surface of the poured lower concrete is soaked in clean water at least 24 hours in advance to allow the concrete to fully absorb water and swell, thereby achieving the purpose of reducing the shrinkage constraint on the newly poured concrete; the wall is poured in layers with a thickness of 500 mm per layer; the longitudinal pouring sequence of the top slab concrete is the same as that of the bottom slab wall, and the transverse pouring sequence of the top slab concrete is to first pour the remaining wall body, and then pour it in layers with a thickness of 300 mm per layer; a wire mesh is arranged at the junction of the two types of concrete and poured at the same time; the heavy concrete is poured first, and the heavy concrete is always kept 30-40 cm higher than the ordinary large-volume concrete.

[0013] For example, in the construction method of the radiation protection system for a proton therapy building provided in one embodiment, the arrangement of the temperature measuring points for concrete temperature measurement in the large-volume heavy concrete construction control method is as follows: at least one point in the center of the bottom plate and the top plate in the thickness direction, and at least one point on the upper and lower surfaces / bottom layers and 50 mm away from the surface / bottom surface and on the same vertical line as the center; at least one point at the bottom center, the middle center, the surface layer 50 mm away from the surface, and the top center or the surface layer 50 mm away from the top surface at 1 / 2 of the length direction of the wall along the height direction; at least one point at a location prone to cracking according to the calculation results of the design documents; three test points are arranged at each temperature measuring point in the thickness direction of the large-volume concrete, that is, temperature measuring lines of different temperatures are pre-buried at one point for surface, middle and lower temperature testing of the bottom plate.

[0014] For example, in the construction method of the radiation protection system for a proton therapy building provided in an embodiment, the concrete curing method in the large-volume heavy concrete construction control method is: the concrete is kept moist for at least 7 days; no one is allowed to go on the concrete and no formwork or brackets are installed before the strength of the concrete reaches 1.2MPa; insulation material is covered on the outer formwork of the foundation to reduce the heat dissipation on the surface of the concrete; after the large-volume concrete is poured, insulation and moisture retention measures are taken to control the temperature difference between the inside and the surface of the concrete within the design requirements; the insulation layer can be removed only after the concrete reaches 30% of the standard strength value, the internal and external temperature difference and the surface and atmosphere minimum, and the internal and external temperature difference and the surface and atmosphere minimum difference are less than 20°C for 48 consecutive hours, and the insulation layer should be removed in layers; during the curing process, if it is found that the surface is whitened due to poor covering or small shrinkage cracks appear, it should be covered immediately, and remedial measures should be taken to strengthen the curing work.

[0015] The beneficial effects of a radiation protection system construction method for a proton therapy building provided in some embodiments of the present application are as follows: to prevent radiation leakage, the present application adopts an ultra-large, ultra-thick, large-volume concrete structure as a radiation protection shielding structure for the accelerator room. The wall panels of the room for the proton therapy building are designed to be high-density, thick, and large-volume heavy concrete with good shielding function to ensure the radiation protection effect, taking into account the temperature control of the large-volume concrete, and controlling the hydration heat of the concrete when the structure thickness reaches 2m (locally 3m), reducing the temperature difference between the inside and outside, and avoiding cracks; to prevent radiation leakage, while ensuring the convenience of construction and the uniformity of concrete, a "tongue-and-groove" construction joint is used for the radiation protection wall to prevent the gap from penetrating, hindering the linear propagation of radiation, and playing a role in radiation protection. The pre-buried casing is used, and the casing is processed into an S-shaped, Z-shaped, etc. shape to replace the ordinary straight-line casing, thereby ensuring the radiation protection effect of the ultra-thick concrete structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a schematic diagram of pouring concrete for the base slab;

[0018] Figure 2 This is a schematic diagram of the layout of the bottom plate temperature measurement points;

[0019] Figure 3 This is a schematic diagram of the arrangement of temperature measurement points on the side wall;

[0020] Figure 4This is a schematic diagram of the layout of the top plate temperature measurement points;

[0021] Figure 5 This is a schematic diagram of the "convex character" of the "tongue and groove" type construction joint;

[0022] Figure 6 It is a schematic diagram of the casing S-type processing structure. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] The present application provides a method for constructing a radiation protection system for a proton therapy building, including a method for controlling the construction of a large-volume heavy concrete and a method for controlling the construction of a radiation protection wall.

[0026] To ensure the radiation protection effect, the wall panels of the computer room must be designed as high-density, thick, large-volume heavy concrete with good shielding function. The extremely strict functional requirements of the accelerator (radiation protection) greatly increase the construction difficulty for the structural crack resistance and impermeability. The construction content includes the construction of large-volume concrete of ultra-thick plates and ultra-thick walls. The choice of construction plan has a great impact on the construction quality. Therefore, it is necessary to take into account the temperature control of large-volume concrete. When the structure thickness reaches 2m (locally 3m), the hydration heat of concrete should be controlled to reduce the temperature difference between the inside and outside and avoid cracks. The large-volume heavy concrete construction control method includes the following steps:

[0027] Preparation of heavy concrete, including concrete raw material control, concrete mix design, concrete trial mix verification and concrete durability testing;

[0028] Concrete pouring, including bottom slab concrete pouring and wall and top slab concrete pouring;

[0029] Concrete temperature measurement to reflect the maximum temperature rise in the concrete casting, the temperature difference between the inside and the outside, the cooling rate and the ambient temperature;

[0030] Concrete curing.

[0031] For example, in the construction method of the radiation protection system for proton therapy buildings provided in one embodiment, the control of concrete raw materials in the large-volume heavy concrete construction control method includes the control of cement, fly ash, mineral powder, magnetite coarse aggregate, iron ore fine aggregate, ordinary fine aggregate, admixtures, special anti-cracking agents, radiation protection additives and mixing water. The raw materials selected for large-volume heavy concrete should have stable performance and meet the requirements of relevant current national and industry specifications, standards and regulations. In addition, the influence of environmental conditions should also be considered so that the prepared concrete meets the design requirements for work, mechanics, volume stability and durability. The key indicators for controlling the raw materials of concrete are as follows:

[0032] (1) Cement

[0033] Cement should meet the requirements of "General Portland Cement" (GB175), and P.O42.5 cement should be selected. The specific surface area should be 300-350 m2 / kg, the alkali content should be less than 0.60%, the C3A content should be less than 8%, and the C3S content should be less than 55%. As an example, Yadong P.O42.5 cement can be used. This cement belongs to medium-low heat cement, and has a low hydration heat, which is conducive to controlling the hydration heat and temperature rise inside the concrete. The specific indicators of cement performance are shown in Table 1:

[0034] Table 1 Specific indicators of cement performance

[0035]

[0036] (2) Fly ash

[0037] Fly ash shall meet the requirements of "Fly ash used in cement and concrete" (GB / T1596), and fly ash of grade II or above shall be used, with a water demand ratio not exceeding 100%, a fluidity ratio of ≥100%, high calcium fly ash or ground fly ash shall not be used, and desulfurization and denitrification ash that releases a strong ammonia smell during the production process is strictly prohibited; for example, as an embodiment, grade II fly ash from Ezhou Power Plant can be used, and an appropriate amount of fly ash can be added, which can not only improve the workability of concrete, but also help improve the pumping performance of concrete, reduce the hydration heat of concrete, and delay the heat peak. The specific performance indicators of fly ash are shown in Table 2:

[0038] Table 2 Specific indicators of fly ash performance

[0039]

[0040] (3) Mineral powder

[0041] The mineral powder should comply with the provisions of GB / T18046. For example, as an example, Wuxin S95 mineral powder is used. Adding an appropriate amount of mineral powder can improve the workability of concrete, improve the pumping performance of concrete, reduce the amount of cement, improve the hydration heat of concrete, and delay the heat peak. The performance indicators of the mineral powder are shown in Table 3:

[0042] Table 3 Specific indicators of mineral powder performance

[0043]

[0044] (4) Magnetite coarse aggregate

[0045] The aggregate of radiation-proof concrete should be magnetite, and hematite, limonite and pyrite should not be used (it affects the molding effect). Iron ore coarse aggregate should be mixed with secondary or multi-graded aggregates to meet the particle grading requirements. The principles for selecting aggregate raw materials mainly consider particle grading, particle shape, apparent density, harmful substance content, Fe3O4 content, etc. Based on this standard, the quality of domestic magnetite is generally average and it is difficult to meet the needs of the project. The indicators of imported magnetite are better, but the cost is high and the supply cannot be guaranteed. This application innovatively passes the first preliminary selection (to select impurities), the second magnetic separation of ore (to select iron ore that meets the requirements), and the third screening of particle grading (to select iron ore that meets the particle grading). The final iron ore has a high quality, and the relevant homogeneity, bulk density, crushing value, harmful impurities, and apparent density are greater than 4200kg / m 3 All of these are magnetite ores that meet the requirements of heavy concrete for iron ore.

[0046] (5) Iron ore fine aggregate

[0047] The fineness modulus and particle size distribution of iron ore fine aggregate should comply with the provisions of medium sand in the medium-graded zone II of JGJ 52. The stone powder content and organic matter content should comply with the provisions of JGJ 52 and the provisions shown in Table 4:

[0048] Table 4 Specific indicators of iron ore fine aggregate

[0049]

[0050] (6) Ordinary fine aggregate

[0051] Ordinary fine aggregate should meet the requirements of "Construction Sand" (GBT 14684-2011). It is advisable to use clean medium-coarse sand with low water absorption and small porosity. The fineness modulus should be 2.4-2.8, not less than 2.3 and higher than 3.0, and the particle gradation should meet the requirements of Zone II; the mud content in the sand should be ≤3.0%, and the mud block content should be ≤1.0%; sea sand, mountain sand and severely weathered porous sand should not be used. For example, as an embodiment, yellow sand is used, and its performance indicators are shown in Table 5:

[0052] Table 5 Specific performance indicators of yellow sand

[0053]

[0054] (7) Additives

[0055] Taking into account that heavy concrete is prepared using magnetite with high apparent density, if it is not properly controlled, it may lead to aggregate sinking and aggregate separation, further increasing the difficulty of crack control in large-volume concrete structures. In severe cases, it may lead to through-cracks that affect the radiation protection performance of the concrete structure. Admixtures with high fluidity, high water reduction rate, high bond stability and high solid content should be selected to ensure that the concrete has good fluidity without segregation, water seepage and aggregate sinking.

[0056] (8) Anti-cracking agent

[0057] Temperature stress plays a leading role in the cracking of ultra-large concrete structures, and the temperature control problem of modern concrete is more prominent. Relying solely on a single existing expansion agent product can no longer effectively solve the temperature shrinkage problem of concrete. In recent years, the technology of using chemical admixtures to regulate hydration heat has gradually received attention. This technology uses chemical admixtures to reduce the hydration heat release rate during the acceleration period of cement hydration, prolong the heat release process during the acceleration period of cement hydration, and make full use of the heat dissipation conditions of the structure to win precious time for structural heat dissipation, thereby achieving the purpose of greatly alleviating the concentrated heat release of hydration, weakening the temperature peak, and prolonging the temperature drop process, thereby reducing the risk of temperature cracking. The combined application of this technology and other technologies such as compensation for shrinkage provides a new idea for solving the problem of ultra-long wall concrete structures and large-volume concrete structures with serious risks of temperature cracking.

[0058] To this end, the special anti-cracking agent for large-volume concrete crack control developed by the Subote Research Institute to address the serious mismatch between the expansion process of existing materials and the temperature and shrinkage processes of concrete can be used. -V concrete (temperature control, anti-seepage) high-efficiency anti-cracking agent, thereby achieving dual regulation of temperature field and expansion process. Temperature field regulation is to intervene in the cement hydration process, adopt cement hydration heat release rate regulation chemical admixtures, and cooperate with the hydration heat release characteristics of admixtures. On the one hand, it reduces the thermal rate of cement hydration acceleration period, wins precious time for structural heat dissipation, thereby weakening the temperature peak and temperature drop process, and reducing the risk of cracking; expansion process regulation is based on the characteristics of the deformation process of the entity structure, using expansion components (calcium oxide, magnesium oxide) with different expansion characteristics to achieve phased and full-process compensation shrinkage. At the same time, the combination of hydration heat regulation materials and calcium oxide and magnesium oxide expansion agents can slow down the temperature rise rate of the structure, avoid the expansion rate of the expansion agent being too fast, win time for the establishment of effective expansion and storage of expansion pressure stress, and enhance its compensation shrinkage effect.

[0059] (9) Radiation protection additives

[0060] The radiation protection additives include elements such as boron and chromium, and the technical requirements of the radiation protection additives should comply with the provisions shown in Table 6 below:

[0061] Table 6 Specific performance indicators of radiation protection additives

[0062]

[0063] (10) Mixing water

[0064] Mixing water shall comply with the provisions of JGJ 63; the inspection items for mixing water shall comply with the provisions of JGJ 63. The inspection frequency shall comply with the provisions of GB 50201.

[0065] For example, in the construction method of the radiation protection system for a proton therapy building provided in one embodiment, the mix design meets the strength and admixture dosage requirements, and in order to improve the crack resistance of concrete, the concrete mix design in the large-volume heavy concrete construction control method should follow the following ideas:

[0066] (1) On the basis of meeting the requirements of concrete strength and workability, by adding mineral admixtures and optimizing the reasonable combination, the amount of cement and cementitious materials can be reduced as much as possible, and the total amount of cementitious materials can be determined according to the optimal principle, which can greatly reduce the heat release of hydration and help control the shrinkage and cracking risks of concrete;

[0067] (2) Reasonable control of the water-binder ratio and maximum water consumption of concrete can reduce the adverse effects of autogenous shrinkage while ensuring strength;

[0068] (3) On the basis of the above steps, an appropriate amount of high-efficiency anti-cracking agent is further added to optimize the heat release process, weaken the hydration heat release temperature peak and early heat release, and on the other hand, produce expansion to compensate for the self-shrinkage and temperature drop shrinkage of the concrete, and improve the crack resistance through the coordinated regulation of the hydration rate and the shrinkage process, thereby inhibiting the cracking of the concrete;

[0069] (4) Use water-reducing polycarboxylic acid high-performance water-reducing agent with a 28d shrinkage ratio of ≤100%. While reducing the water consumption per cubic meter of concrete, it does not increase the shrinkage of concrete, improves the working performance of concrete, and at the same time densifies the concrete, improving its mechanical properties and durability. In addition, proper air entrainment in concrete can improve the homogeneity, pumping performance and ultimate tensile value of concrete, improve the workability of concrete, and prevent excessive floating slurry during pouring, which may cause concrete cracking.

[0070] Based on the requirements of crack resistance of the main structure concrete of the proton center, combined with the above concrete mix design principles, combined with similar engineering experience and simulation calculation results, that is, the wall concrete has the highest risk of cracking, followed by the top plate, and the bottom plate has the lowest risk of cracking. Therefore, for the main structure concrete, 8% of -V concrete (temperature control, anti-seepage) high-efficiency anti-cracking agent and anti-cracking fiber can achieve good working, mechanical and durability properties while having anti-cracking properties that meet the requirements of this application.

[0071] For example, in the radiation protection system construction method for a proton therapy building provided in one embodiment, the concrete trial mixing verification in the large-volume heavy concrete construction control method includes: on the basis of meeting the working performance, mechanical properties, durability and crack resistance of the concrete, the concrete mix ratio is determined according to multiple trial mixing verifications, and the mix ratio uses magnetite ore and magnetite sand as coarse aggregate, which is mainly used for proton area construction.

[0072] For example, in the radiation protection system construction method for a proton therapy building provided in one embodiment, the concrete durability test in the large-volume heavy concrete construction control method includes: conducting a frost resistance test, a permeability test, a non-contact shrinkage test, a chloride ion penetration test, and an early crack resistance test on the heavy concrete, so that various indicators meet the performance requirements of heavy concrete.

[0073] After the concrete raw materials are well controlled, concrete transportation is required. Concrete transportation includes off-site transportation and on-site transportation:

[0074] In off-site transportation, given the importance of the proton therapy building, multiple alternative transportation routes can be used to schedule and monitor in a timely manner through GPS information to ensure that the supply of concrete is not affected by traffic during construction. At the same time, in order to avoid congestion during peak hours in the morning and evening, an alternative route is selected before construction to avoid congestion during peak hours;

[0075] During on-site transportation: arrange for special personnel to be on duty to direct on-site traffic and avoid traffic jams caused by concrete pump trucks. Traffic safety commanders should be set up at the entrances and exits of the construction site. The roads on the construction site should be smooth, and circular lanes should be set up when conditions permit. Warning signs should be set up in dangerous areas. Good lighting should be provided during nighttime construction.

[0076] For example, in the construction method of the radiation protection system for the proton therapy building provided in one embodiment, the selection principle of the concrete pump for concrete pouring in the large-volume heavy concrete construction control method is: according to the characteristics of the proton therapy building project: large concrete pouring volume, high pouring quality requirements, and no cold joints, cracks, etc., a truck pump is used for on-site pumping. The place where the concrete pump truck is set up should have a flat and solid site, unobstructed roads, convenient material feeding, close to the pouring site, convenient piping, close to drainage facilities and convenient water and power supply, and does not affect the smoothness of the construction road.

[0077] The method for pouring bottom slab concrete in the large-volume heavy concrete construction control method is as follows:

[0078] (1) The bottom slab concrete pouring adopts the method of oblique advancement and layered pouring, such as Figure 1 As shown, the pouring thickness of each layer is 400-600mm, and the construction is organized in a way of advancing obliquely from the far end to the pump direction;

[0079] (2) Concrete vibration adopts an inserted vibrator. The vibrating rod is required to be inserted quickly and pulled out slowly to ensure that the vibrating rod is inserted deep enough and the concrete has sufficient time to be vibrated and compacted. The spacing of the vibration points is 1.5 times the effective radius of the vibrating rod, generally controlled at 400-500mm. The vibration time is controlled to the point that the concrete no longer sinks and no bubbles are generated. The vibration should be carried out evenly and orderly with the progress of material feeding. No vibration should be missed and no over-vibration should be allowed.

[0080] (3) Multiple vibrations are required in areas with dense reinforcement to ensure that the concrete is densely packed. The vibration time should not be too long at a time to prevent local concrete from over-vibration and segregation. In areas where embedded parts and reinforcement are densely interlaced, thick reinforcement bars should be used to assist in manual insertion and tamping.

[0081] For example, in the construction method of the radiation protection system for a proton therapy building provided in one embodiment, the wall and top slab concrete pouring method in the large-volume heavy concrete construction control method is:

[0082] (1) The slump of the wall and top slab concrete poured into the mold is controlled within 160-200 mm, and the air content is controlled within ≤5%;

[0083] (2) In order to reduce the constraints of the cast concrete on the shrinkage of the newly cast concrete, the characteristics of concrete "shrinkage when dry and expansion when wet" are used. Before the upper side wall and top slab concrete is cast, the upper surface of the cast lower concrete is soaked in clean water at least 24 hours in advance to allow the concrete to fully absorb water and expand, thereby achieving the purpose of reducing the constraints on the shrinkage of the newly cast concrete;

[0084] (3) The wall is cast in layers with a thickness of 500 mm per layer;

[0085] (4) The longitudinal pouring sequence of the top slab concrete is the same as that of the bottom slab wall. The transverse pouring sequence of the top slab concrete is to first pour the remaining wall, and then pour in layers with a thickness of 300 mm each;

[0086] (5) Wire mesh is arranged at the junction of the two types of concrete and poured simultaneously; heavy concrete is poured first, and the heavy concrete is always kept 30-40 cm higher than the ordinary mass concrete to prevent the ordinary mass concrete from flowing into the heavy concrete area and affecting the overall radiation protection performance.

[0087] For example, in the construction method of the radiation protection system for a proton therapy building provided in one embodiment, the arrangement of monitoring points in the concrete casting body should truly reflect the maximum temperature rise, the temperature difference between the inside and the outside, the cooling rate and the ambient temperature of the concrete casting body. The arrangement of the temperature measurement points for concrete temperature measurement in the large-volume heavy concrete construction control method is as follows:

[0088] At least one location in the center of the thickness direction of the bottom plate and top plate, at least one location on the upper and lower surfaces / bottom layers and 50mm away from the surface / bottom surface and on the same vertical line as the center; at least one location in the center of the bottom, the center of the middle, the surface layer 50mm away from the surface, and the center of the top or the surface layer 50mm away from the top surface at 1 / 2 of the length direction of the wall along the height direction; at least one location in the crack-prone area according to the calculation results of the design documents;

[0089] The horizontal temperature measurement point spacing of large volume concrete is as follows: Figure 2-4 As shown, Figure 2 This is the layout diagram of the bottom plate temperature measurement points. Figure 3 This is the layout diagram of the temperature measurement points on the side wall. Figure 4 This is the layout diagram of the top plate temperature measurement points.

[0090] Three test points are arranged at each temperature measuring point along the thickness direction of large-volume concrete, that is, temperature measuring wires with different temperatures are pre-buried at one point for testing the surface, middle and lower temperatures of the bottom plate. According to the temperature measuring area, φ10 steel bars are prepared as attachment rods for the temperature measuring wires. The temperature measuring wires corresponding to different plate thicknesses are tied to the steel bars in sequence. The temperature sensitive elements of the temperature measuring wires must not touch the steel bars. The temperature measuring wires and φ10 steel bars should be waterproofed to avoid leakage of the bottom plate. When measuring temperature, portable instruments, temperature measuring probes, and temperature measuring wires are used together, and the temperature measuring points are numbered and the temperature measurement records are made so that problems can be found at any time.

[0091] For example, in the construction method of the radiation protection system for a proton therapy building provided in one embodiment, the concrete curing method in the large-volume heavy concrete construction control method is:

[0092] (1) The concrete should be kept moist for at least 7 days, preferably for more than 14 days;

[0093] (2) No one is allowed to enter the concrete before the concrete strength reaches 1.2 MPa, and no formwork or support is allowed to be installed;

[0094] (3) Cover the outer formwork of the foundation with insulation material to reduce heat dissipation from the concrete surface;

[0095] (4) After the mass concrete is poured, insulation and moisture retention measures should be taken to control the temperature difference between the interior and surface of the concrete within the design requirements;

[0096] (5) The insulation layer can only be removed after the concrete reaches 30% of the standard strength value, the temperature difference between the inside and outside and the temperature difference between the surface and the atmosphere are the lowest, and the temperature difference between the inside and outside and the temperature difference between the surface and the atmosphere are all less than 20°C for 48 consecutive hours. The insulation layer should be removed layer by layer.

[0097] (6) During the maintenance process, if the surface is found to be white or has small cracks due to shrinkage due to poor coverage, it should be covered immediately and maintenance work should be strengthened and remedial measures should be taken.

[0098] The radiation protection wall construction control method includes adopting a "tongue-and-groove" shaped construction joint and pre-buried curved or broken line sleeves to hinder the linear propagation of radiation.

[0099] Specifically, ultra-thick wall panels and high-density heavy concrete structures are used to shield radiation. The thickness of concrete components is between 1000-3850mm. To ensure construction safety and the quality of ultra-thick concrete, and in combination with concrete radiation protection requirements, the accelerator room structure is constructed in eleven stages. To prevent radiation leakage, while ensuring construction convenience and concrete uniformity, "tongue-and-groove" construction joints are used to prevent gap penetration, hinder the linear propagation of radiation, and play a role in radiation protection. The "tongue-and-groove" construction joints are "convex" as shown in the figure. Figure 5As shown; and it is not suitable to use the construction technology of post-grooving and hole-making. All pre-buried casings are used, and the casings are processed into S-shaped, Z-shaped and other shapes. Figure 6 The figure shows a schematic diagram of an S-shaped casing structure, which replaces a common straight casing and ensures the radiation protection effect of an ultra-thick concrete structure.

[0100] The construction method of the radiation protection system for proton therapy buildings in the present application controls the hydration heat, the temperature difference between the inside and outside of the structure, the maximum center temperature, etc. to meet the regulatory requirements to avoid cracks by measuring the concrete temperature; and avoids cracks caused by concrete shrinkage by adjusting the aggregate particle grading and sand ratio, admixtures, and controlling the production, pouring and maintenance of concrete.

[0101] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes, and it can be fully applicable to various fields suitable for the present application. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for constructing a radiation protection system for a proton therapy building, characterized in that: The invention comprises a large-volume heavy concrete construction control method and a radiation protection wall construction control method, wherein the large-volume heavy concrete construction control method comprises the following steps: Preparation of heavy concrete, including concrete raw material control, concrete mix design, concrete trial mix verification and concrete durability testing; Concrete pouring, including bottom slab concrete pouring and wall and top slab concrete pouring; Concrete temperature measurement to reflect the maximum temperature rise in the concrete casting, the temperature difference between the inside and the outside, the cooling rate and the ambient temperature; Concrete curing; The radiation protection wall construction control method includes adopting a "tongue-and-groove" shaped construction joint and pre-buried curved or broken line casing to hinder the linear propagation of radiation.

2. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The control of concrete raw materials in the large-volume heavy concrete construction control method includes the control of cement, fly ash, mineral powder, magnetite coarse aggregate, iron ore fine aggregate, common fine aggregate, admixture, special anti-cracking agent, radiation protection additive and mixing water.

3. The construction method of the radiation protection system for a proton therapy building according to claim 2, characterized in that: In the control of the concrete raw materials, the specific surface area of ​​cement is 300-350 m2 / kg, the alkali content is less than 0.60%, the C3A content is less than 8%, and the C3S content is less than 55% to control the hydration heat and temperature rise inside the concrete; the water demand ratio of fly ash does not exceed 100%, and the fluidity ratio is ≥100%; the magnetite coarse aggregate is mixed with secondary or multi-graded aggregates to meet the particle grading requirements; the fineness modulus and particle grading of the iron ore fine aggregate meet the requirements of the medium sand in the medium grading zone II of JGJ 52, the stone powder content and organic matter content meet the requirements of JGJ 52, and the apparent density is ≥3700 kg / m 3 , mud content ≤0.5%, firmness ≤8%, chloride ion content ≤0.02%, sulfide and sulfate content calculated as SO3 ≤0.5%, and radioactivity complies with the provisions of GB6566; ordinary fine aggregate uses clean medium and coarse sand with low water absorption and small porosity, the fineness modulus is 2.4-2.8, and the particle grading meets the requirements of Zone II, the mud content in the sand ≤3.0%, and the mud content ≤1.0%; the admixture has high solid content, high water reduction rate, high fluidity and high bond stability; the radiation protection additive contains boron and chromium elements, the water content of the radiation protection additive is ≤10%, the free calcium oxide content is ≤3.0%, the chloride ion content is ≤0.02%, and the sulfur trioxide content is ≤4.0%.

4. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The concrete mix design in the mass heavy concrete construction control method comprises the following steps: (1) On the basis of meeting the requirements of concrete strength and workability, the amount of cement and cementitious materials can be reduced by adding mineral admixtures and optimizing the mix. The total amount of cementitious materials can be determined according to the optimal principle to reduce the heat released by hydration, which is beneficial to controlling the shrinkage and cracking risks of concrete; (2) Reasonable control of the water-binder ratio and maximum water consumption of concrete to reduce the adverse effects of autogenous shrinkage while ensuring strength; (3) Further adding an appropriate amount of high-efficiency anti-cracking agent on the basis of the above steps, improving the crack resistance through coordinated regulation of hydration rate and shrinkage process, and inhibiting concrete cracking; (4) Use water-reducing polycarboxylic acid high-performance water-reducing agent with a 28d shrinkage ratio of ≤100%. While reducing the water consumption per cubic meter of concrete, it does not increase the shrinkage of concrete, improves the working performance of concrete, and at the same time densifies the concrete, improving its mechanical properties and durability. In addition, appropriate air entrainment in the concrete can improve the homogeneity, pumping performance and ultimate tensile value of the concrete, and improve the workability of the concrete.

5. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The concrete trial mix verification in the large-volume heavy concrete construction control method includes: on the basis of meeting the concrete working performance, mechanical properties, durability and crack resistance, the concrete mix ratio is determined according to multiple trial mix verifications, and the mix ratio uses magnetite and magnetite sand as coarse aggregate, which is mainly used for proton zone construction.

6. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The concrete durability test in the large-volume heavy concrete construction control method includes: conducting a frost resistance test, a permeability test, a non-contact shrinkage test, a chloride ion penetration test, and an early crack resistance test on the heavy concrete, so that various indicators meet the performance requirements of the heavy concrete.

7. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The method for pouring bottom slab concrete in the mass heavy concrete construction control method is as follows: The bottom slab concrete pouring adopts the method of oblique advancement and layered pouring. The pouring thickness of each layer is 400-600mm, and the construction is organized by oblique advancement from the far end to the pump direction. Concrete vibration adopts an inserted vibrator. The vibrating rod is required to be inserted quickly and pulled out slowly to ensure that the vibrating rod is inserted deep and the concrete has sufficient time to be vibrated and compacted. The spacing of the vibration points is 1.5 times the radius of the vibrating rod, generally controlled at 400-500mm. The vibration time is controlled when the concrete stops sinking and no bubbles are generated. Vibration should be carried out evenly and orderly with the progress of material feeding; Multiple vibrations are required in areas with dense steel bars to ensure that the concrete is densely packed. The vibration time should not be too long at a time to prevent local concrete segregation due to over-vibration. In areas where embedded parts and steel bars are densely interlaced, thick steel bars should be used with the assistance of manual insertion.

8. The construction method of the radiation protection system for a proton therapy building according to claim 7, characterized in that: The wall and top slab concrete pouring method in the large-volume heavy concrete construction control method is: The slump of the wall and top slab concrete poured into the mold is controlled at 160-200mm, and the air content is controlled at ≤5%; Before pouring the upper side wall and top slab concrete, soak the upper surface of the poured lower concrete with clean water at least 24 hours in advance to allow the concrete to fully absorb water and swell, thereby reducing the shrinkage constraint on the newly poured concrete; The wall is poured in layers with each layer being 500mm thick; The longitudinal pouring sequence of the top slab concrete is the same as that of the bottom slab wall. The transverse pouring sequence of the top slab concrete is to first pour the remaining wall, and then pour in layers with a thickness of 300mm per layer. Choose to arrange wire mesh at the junction of the two types of concrete and pour them at the same time; pour the heavy concrete first, and always keep the heavy concrete 30-40cm higher than the ordinary large-volume concrete.

9. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The arrangement of the temperature measurement points for concrete temperature measurement in the large-volume heavy concrete construction control method is as follows: At least one location in the center of the thickness direction of the bottom plate and top plate, at least one location on the upper and lower surfaces / bottom layers and 50mm away from the surface / bottom surface and on the same vertical line as the center; at least one location in the center of the bottom, the center of the middle, the surface layer 50mm away from the surface, and the center of the top or the surface layer 50mm away from the top surface at 1 / 2 of the length direction of the wall along the height direction; at least one location in the crack-prone area according to the calculation results of the design documents; Three test points are arranged at each temperature measuring point along the thickness direction of large volume concrete, that is, temperature measuring wires with different temperatures are pre-buried at one point, which are used for surface, middle and lower temperature testing of the bottom plate.

10. The construction method of the radiation protection system for a proton therapy building according to claim 1, characterized in that: The concrete curing method in the large-volume heavy concrete construction control method is: The concrete should be kept moist for at least 7 days; Before the concrete strength reaches 1.2MPa, no one is allowed to go on it or install formwork or brackets; Cover the outer formwork of the foundation with insulation material to reduce heat dissipation from the concrete surface; After the mass concrete is poured, insulation and moisture retention measures should be taken to control the temperature difference between the interior and surface of the concrete within the design requirements; The insulation layer can be removed only after the concrete reaches 30% of the standard strength value, the temperature difference between the inside and outside and the temperature difference between the surface and the atmosphere are both lower than 20°C for 48 consecutive hours. The insulation layer should be removed step by step; During the maintenance process, if it is found that the surface is not covered strictly and turns white or small cracks appear due to shrinkage, it should be covered immediately, and maintenance work should be strengthened and remedial measures should be taken.

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