Construction method of ultra-large-volume concrete structure for linear accelerator

Abstract

The invention belongs to the technical field of medical engineering, and particularly relates to a construction method of an ultra-large-volume concrete structure for a linear accelerator, which comprises concrete raw material selection and mix proportion design, design of a building template supporting and reinforcing system, and crack control measures of the ultra-large-volume concrete structure for the linear accelerator. A building formwork supporting and reinforcing system comprises a wall formwork supporting system, a top plate side formwork supporting system, a top plate formwork supporting system and a method for arranging split bolt joint positions between walls and plates. The building formwork supporting and reinforcing system has the beneficial effects that crack control is conducted on an engineering structure from the whole process of concrete raw materials, additives and the construction technology, and the construction efficiency is improved; the split bolts and the cooling water circulation cooling pipe network enhance the integrity and stability of the wall body and prevent the formwork from expanding, so that rays emitted by the linear accelerator are effectively shielded.

Description

Technical Field

[0001] The invention relates to the technical field of medical engineering, and in particular to a construction method of an ultra-large volume concrete structure for a linear accelerator. Background Art

[0002] The high-energy electromagnetic radiation of medical electron linear accelerators can cause harm to surrounding medical personnel, so the linear accelerator must be installed in a large concrete structure with radiation protection function. The bottom plate, side wall and top plate of the structure all need to be poured with large concrete. However, when the concrete is constructed on site, the through-type tension bolt reinforcement form is difficult to meet the construction requirements. The main reason is that the construction is difficult and it is easy to leave construction joints and through cracks, which affects the crack resistance and integrity of the concrete, and further affects the radiation protection effect of the engineering structure. Summary of the invention

[0003] The present invention is aimed at the above-mentioned problems and specifically designs a construction method for a super-large concrete structure for a linear accelerator, which controls cracks in the engineering structure from the perspective of the entire process of concrete raw materials, additives and construction technology.

[0004] To achieve the above object, the present invention provides a construction method for a super-large concrete structure for a linear accelerator, comprising the following steps: Step 1: Select the raw materials for concrete and design the mix ratio. Ordinary Portland cement is selected as the cementitious material. Non-alkali-active coarse aggregate, crushed stone with a particle size of 5-10 mm, crushed stone with a particle size of 10-20 mm, continuous grading is used for aggregate grading, and machine-made medium sand is used for fine aggregate. Step 2: Building formwork support reinforcement system, including wall formwork support system, top plate side formwork support system, top plate formwork support system, and the setting method of the tension bolt node between the wall and the plate; Step 3: Control of cracks in concrete structure: After the reinforcement of the wall and top plate of the linear accelerator room is tied, before the template is installed, a cooling water circulation cooling pipe network made of galvanized steel pipes is installed between the wall steel meshes, and the steel pipe risers are fixed to the additional reinforcement of the wall steel meshes with wire ties; After the steel mesh in the middle layer of the floor slab is tied, the cooling water circulation and cooling pipe network is installed horizontally in the floor slab; Step 4. After the concrete curing period is over, use high-grade expansive cement mortar for grouting and filling. Pour the prepared grouting material into the cooling water pipe from a low point until grouting material flows out from a high point of the cooling water pipe. Seal the water outlet, continue to hold the pressure for 30 seconds, and then seal the grouting hole.

[0005] Furthermore, in the step 1, F·II grade fly ash and S95 grade mineral powder are added into the concrete.

[0006] Furthermore, in the step 1, the concrete is mixed with admixtures, and a slow-setting high-efficiency water-reducing agent and a SY-G high-performance expansion anti-cracking agent are added.

[0007] Furthermore, in step 1, the concrete slump is required to be 180±20 mm and the bulk density is not less than 2.35 t / m³.

[0008] Preferably, in the step 1, the amount of silicate cement is 210kg / m³, the amount of crushed stone with a particle size of 5-10mm is 220kg / m³, the amount of crushed stone with a particle size of 10-20mm is 820kg / m³, the fineness modulus of sand in the machine-made sand is 2.6, and the amount is 785kg / m³; the amount of F·Ⅱ grade fly ash is 65kg / m³, the amount of S95 grade mineral powder is 95kg / m³, the amount of slow-setting high-efficiency water reducing agent is 8.5kg / m³, and the amount of SY-G type high-performance expansion anti-cracking agent is 35kg / m³.

[0009] Furthermore, in the step 2, the wall formwork is assembled with thick plywood to form the panel, square steel is used as the secondary rib, double steel pipes are used as the main rib, and tension bolts are set between the relative formworks; the top plate side formwork is made of thick coated plywood, square steel is used as the secondary back rib, double steel pipes are used as the main rib, and tension bolts are set between the formworks; the top plate formwork is made of thick plywood, square steel is used as the secondary keel, channel steel is used as the main keel, and the support system adopts a disc-type steel pipe full-span support frame, and the top of the neutral rod of the support frame is connected to the main keel through an adjustable bracket.

[0010] Furthermore, in the tension bolt node method in step 2, tension bolts with an inclination angle of 45° are used to connect two adjacent formworks at the corners of the wall, cross-arranged tension bolts with an inclination angle of 45° are used at the intersection of the T-shaped wall to connect the wing plate at the corner of the T-shaped wall and the wall plate opposite to the wing plate, and tension bolts are used to connect the two opposite formworks in the local thickened area of ​​the wall.

[0011] Furthermore, in step three, the cooling water pipes are arranged along the length direction of the wall, and the outermost cooling water pipes are 1.5m to 2.0m away from the edge of the concrete; the water inlet of the cooling water pipe is connected to the on-site loop temporary fire-fighting pipeline, and a gate valve is set at the interface.

[0012] Furthermore, in step three, when the cooling water temperature is too high, the water inlet flow rate and water temperature are adjusted to keep the temperature difference between the water inlet and the inner side of the concrete between 15°C and 25°C, and the difference between the outlet water temperature and the inlet water temperature between 3°C and 6°C.

[0013] Furthermore, in step 4, during the burying and pouring process of the cooling water pipe, the joint part is sealed by wrapping with tape.

[0014] In summary, the present invention has the following advantages and beneficial technical effects: 1. In order to reduce the hydration heat, the present invention reduces the amount of cement as much as possible under the premise of ensuring the quality of concrete, selects ordinary silicate cement with good crack resistance and low hydration heat; in order to ensure the cohesiveness, water retention and fluidity of the concrete mixture, fly ash and mineral powder are added, which not only improves the workability of the concrete and increases the density of the concrete, but also replaces part of the cement material and further reduces the hydration heat; the added admixture has efficient water reduction and slump protection effects, can better improve the stratification and bleeding phenomena of concrete, and improve the anti-segregation ability of concrete.

[0015] 2. The setting of the tension bolts in the present invention is used to enhance the integrity and stability of the wall, prevent the formwork from expanding, and ensure that the spacing between the inner and outer formworks meets the design requirements, thereby ensuring the integrity, rigidity and strength of the formwork structure; installing the tension bolts at an angle of 45° can increase the friction between the bolts and the formwork, thereby preventing the bolts from loosening during the concrete pouring process. This installation method enables the bolts to better resist rotation and loosening when subjected to lateral force, thereby ensuring the shear resistance and stability of the formwork and the pouring quality of concrete, thereby effectively shielding the rays emitted by the linear accelerator.

[0016] 3. The present invention installs a cooling water circulation cooling device in the template to control and reduce the temperature in the template. The cooling water circulates in the pipe network and takes away the heat in the template through the thermal conductivity of the water pipe, thereby taking away the heat released by the concrete to achieve the purpose of cooling. This helps to reduce the temperature stress and cracks caused by the hydration heat of the concrete. In addition, the water outlet can also be used for sprinkling and curing of concrete on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 It is a schematic diagram of a part of the structure of the top plate in the present invention; Figure 2 It is a schematic diagram of the reinforcement method of the template at the corner of the wall in the present invention; Figure 3 It is a schematic diagram of the reinforcement method of the template at the intersection of the T-shaped wall in the present invention; Figure 4 It is a schematic diagram of the reinforcement method of the template in the local thickening area of ​​the wall in the present invention.

[0018] The reference numerals in the accompanying drawings are: 1. Channel steel; 2. Square steel; 3. Thick plywood; 4. Tension bolts. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the implementation of the present invention clearer, the technical solution in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions; the described embodiments are part of the embodiments of the present invention, not all of the embodiments; the embodiments and directional terms described below with reference to the drawings are exemplary and intended to be used to explain the present invention, and cannot be understood as limitations on the present invention; based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings: The following is combined with Figure 1-Figure 4 The present invention is described in further detail: like Figure 1-Figure 4 As shown, this embodiment discloses a construction method for a super-large concrete structure for a linear accelerator, comprising the following steps: Step 1: Concrete raw material selection and mix ratio design. To reduce hydration heat, the amount of cement should be minimized while ensuring the quality of concrete. Ordinary Portland cement P·O42.5 with good crack resistance and low hydration heat should be selected, with a dosage of 210kg / m³. Coarse aggregate uses non-alkali-active coarse aggregate with a mud content of less than 0.9%, crushed stone with a particle size of 5-10mm, a dosage of 220kg / m³, and crushed stone with a particle size of 10-20mm, a dosage of 820kg / m³, and continuous grading is maintained; fine aggregate uses machine-made medium sand with a fineness modulus of 2.6 and a dosage of 785kg / m³; In order to ensure the cohesiveness, water retention and fluidity of the concrete mixture, 65kg / m³ of F·Ⅱ grade fly ash and 95kg / m³ of S95 grade mineral powder are added into the concrete; Add admixtures to the concrete, including 8.5kg / m³ slow-setting high-efficiency water-reducing agent and 35kg / m³ SY-G high-performance expansion anti-cracking agent; The concrete slump requirement is 180±20mm, and the bulk density is not less than 2.35t / m³; Step 2: Formwork support reinforcement system. The preferred thickness of the side walls of the engineering structure associated with the present invention is: 1700mm, 2200mm, 2500mm, 3000mm, the preferred thickness of the top plate is: 1700mm, 3000mm, and the concrete strength grade is C35.

[0020] 1) The parameters of the wall formwork support system are as follows: 2) The side formwork of the top plate in the side formwork support system adopts 15mm thick film-coated plywood, the vertically arranged square steel 2 is used as the secondary back rib, with a spacing of 150mm, the horizontally arranged double steel pipes are used as the main rib, with a spacing of 350mm, the specification of the tension bolts 4 is M16, and the horizontal spacing is 350mm; the tension bolts 4 of this length and size specification use two M16 tension bolts 4, and the C16 steel bars are welded in the middle to extend the length, the double-sided welding lap length is ≥5d, and the single-sided welding ≥10d; 3) If Figure 1 As shown in the figure, the top plate formwork support system is designed with the following parameters: 4) Setting method of 4-node position of wall and slab tension bolts like Figure 2 As shown, at the corner of the wall, multiple M16 tension bolts 4 with an inclination angle of 45° are set, and the adjacent spacing is 400mm, as a reinforcement measure for two adjacent templates. Multiple tension bolts 4 are set at the other wall positions to connect the two opposite templates, and the spacing of the tension bolts 4 is 350mm; like Figure 3 As shown, two pairs of tension bolts 4 are cross-set at the intersection of the T-shaped wall and are inclined at an angle of 45°, as a reinforcement measure for the wing plate at the corner and the wall plate opposite to the wing plate. Multiple tension bolts 4 are set at the other wall positions to connect the two opposite templates. The spacing between the tension bolts 4 is preferably: 200mm, 350mm; like Figure 4 As shown, in the local thickening area of ​​the wall, multiple groups of tension bolts 4 are set along the direction of the wall to connect the two opposite templates, with a spacing of 200mm, and tension bolts 4 are set perpendicular to the direction of the wall to connect the two opposite templates, with a spacing of 150mm; Step 3: Crack control measures for ultra-large concrete structures for linear accelerators: After the reinforcement of the wall and top plate of the linear accelerator room is tied, before the template is installed, a cooling water circulation and cooling pipe network made of DN32 galvanized steel pipes is installed between the wall steel meshes, and the steel pipe risers are reliably fixed on the additional reinforcement of the wall steel mesh with wires; after the reinforcement of the middle layer of the floor slab is tied, a set of cooling water circulation and cooling pipe network is installed horizontally in the floor slab using DN32 galvanized steel pipes; The cooling water pipes are arranged along the length of the wall, with a vertical spacing of 2m along the wall, and the outermost cooling water pipe is 1.5m~2.0m away from the edge of the concrete; the water inlet of the cooling water pipe is connected to the temporary fire-fighting pipeline of the loop on site, and a DN50 gate valve is installed at the interface to facilitate timely control of opening and closing, and the water outlet is used for sprinkling and curing of concrete on site; When the cooling water temperature is too high, cold water should be added at the water inlet to make the water temperature at the water inlet lower than the temperature inside the concrete, the temperature difference is maintained between 15℃ and 25℃, and the difference between the outlet water temperature and the inlet water temperature is maintained between 3℃ and 6℃; the cooling rate should not be greater than 2℃ / d, and should not be greater than 1℃ / 4h; Step 4: During the laying and pouring of cooling water pipes, the joints are sealed with tape to prevent water leakage. After the concrete curing period, high-grade expansive cement mortar with a sand-to-water ratio of 1:0.5 is used for grouting and filling. The prepared grouting material is poured into the cooling water pipe from a low point until grouting material flows out from a high point of the cooling water pipe. The water outlet is sealed, and the pressure is maintained for 30 seconds before sealing the grouting hole.

[0021] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A construction method for a super-large concrete structure for a linear accelerator, characterized in that: The following steps are involved: Step 1: Select the raw materials for concrete and design the mix ratio. Ordinary Portland cement is selected as the cementitious material. Non-alkali-active coarse aggregate, crushed stone with a particle size of 5-10 mm, crushed stone with a particle size of 10-20 mm, continuous grading is used for aggregate grading, and machine-made medium sand is used for fine aggregate. Step 2: Building formwork support reinforcement system, including wall formwork support system, top plate side formwork support system, top plate formwork support system, and the setting method of the tension bolt node between the wall and the plate; Step 3: Control of cracks in concrete structure: After the reinforcement of the wall and top plate of the linear accelerator room is tied, before the template is installed, a cooling water circulation cooling pipe network made of galvanized steel pipes is installed between the wall steel meshes, and the steel pipe risers are fixed to the additional reinforcement of the wall steel meshes with wire ties; After the steel mesh in the middle layer of the floor slab is tied, the cooling water circulation and cooling pipe network is installed horizontally in the floor slab; Step 4. After the concrete curing period is over, use high-grade expansive cement mortar for grouting and filling. Pour the prepared grouting material into the cooling water pipe from a low point until grouting material flows out from a high point of the cooling water pipe. Seal the water outlet, continue to hold the pressure for 30 seconds, and then seal the grouting hole.

2. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In the step 1, F·II grade fly ash and S95 grade mineral powder are added into the concrete.

3. The construction method of a super-massive concrete structure for a linear accelerator according to claim 2, characterized in that: In the step 1, concrete is mixed with admixtures, and a slow-setting high-efficiency water-reducing agent and a SY-G high-performance expansion anti-cracking agent are added.

4. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In the step 1, the concrete slump is required to be 180±20mm and the bulk density is not less than 2.35t / m³.

5. The construction method of a super-massive concrete structure for a linear accelerator according to claim 3, characterized in that: In the step 1, the amount of silicate cement is 210kg / m³, the amount of crushed stone with a particle size of 5-10mm is 220kg / m³, the amount of crushed stone with a particle size of 10-20mm is 820kg / m³, the fineness modulus of sand in the machine-made sand is 2.6, and the amount is 785kg / m³; the amount of F·Ⅱ grade fly ash is 65kg / m³, the amount of S95 grade mineral powder is 95kg / m³, the amount of slow-setting high-efficiency water reducing agent is 8.5kg / m³, and the amount of SY-G type high-performance expansion anti-cracking agent is 35kg / m³.

6. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In the step 2, the wall formwork is assembled with thick plywood to form the panel, square steel is used as the secondary rib, double steel pipes are used as the main rib, and tension bolts are set between the relative formworks; the top plate side formwork is made of thick coated plywood, square steel is used as the secondary back rib, double steel pipes are used as the main rib, and tension bolts are set between the formworks; the top plate formwork is made of thick plywood, square steel is used as the secondary keel, channel steel is used as the main keel, and the support system adopts a disc-type steel pipe full-span support frame, and the top of the neutral rod of the support frame is connected to the main keel through an adjustable bracket.

7. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In the second step, the tension bolt node method is to use tension bolts with an inclination angle of 45° to connect the two adjacent formworks at the corners of the wall, and cross-set tension bolts with an inclination angle of 45° are used at the intersection of the T-shaped wall to connect the wing plate at the corner of the T-shaped wall and the wall plate opposite to the wing plate. Tension bolts are used to connect the two opposite formworks in the local thickened area of ​​the wall.

8. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In the step three, the cooling water pipes are arranged along the length direction of the wall, and the outermost cooling water pipes are 1.5m to 2.0m away from the edge of the concrete; the water inlet of the cooling water pipe is connected to the temporary fire-fighting pipeline of the loop on site, and a gate valve is set at the interface.

9. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In step three, when the cooling water temperature is too high, the water inlet flow rate and water temperature are adjusted to keep the temperature difference between the water inlet and the inner side of the concrete between 15°C and 25°C, and the difference between the outlet water temperature and the inlet water temperature between 3°C and 6°C.

10. The construction method of a super-massive concrete structure for a linear accelerator according to claim 1, characterized in that: In the step 4, during the burying and pouring process of the cooling water pipe, the joint part is sealed by wrapping with tape.

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