Steel plate composite concrete protection structure and design method thereof

Abstract

The invention relates to a steel plate composite concrete protection structure which comprises an outer side steel plate, a foam energy absorption layer and a concrete layer, the outer side steel plate is located on the outermost side of the protection structure, and the foam energy absorption layer is located on the inner side of the outer side steel plate; the concrete layer is located on the inner side of the protection structure compared with the foam energy absorption layer; the invention further relates to a design method of the protection structure, the design method is used for designing the protection structure, and the design method comprises the first step of determining the maximum impact energy needing to be borne by the protection structure, the second step of determining the total energy capable of being absorbed by the protection structure, and the third step of determining the maximum impact energy needing to be borne by the protection structure. The maximum impact energy needing to be borne by the protection structure is compared with the total energy capable of being absorbed by the protection structure. The protection structure has the advantages of being good in impact resistance, small in protection structure section thickness, light in structure, simplified in construction and the like, and the protection structure designed according to the design method is more practical.

Description

Technical Field

[0001] The present application relates to the field of nuclear power engineering technology, and in particular to a steel plate composite concrete protective structure and a design method thereof. Background Art

[0002] Due to the complexity and particularity of the functions of nuclear power plants, once the structure of a nuclear power plant is destroyed, a large amount of radioactive materials will leak out, with very serious consequences. Therefore, under external impact loads, especially when facing the impact of large missiles (such as commercial large aircraft), how to improve the safety performance of the protective structure of nuclear power plants, reduce the damage to the internal structure, and ensure its functionality and safety is a problem worthy of attention. At present, the common nuclear power plant protective structure at home and abroad is the traditional reinforced concrete structure. In order to achieve the integrity of the internal structure in response to the impact of large missiles, the thickness of the protective structure is usually more than one meter, and the steel bars inside the concrete are densely arranged. There are problems such as low impact resistance, heavy structure, complex construction, long construction period, and high cost.

[0003] Other protective structures are also disclosed in the prior art. For example, CN114352086A discloses an impact-resistant containment structure, which includes: a cylinder with a circular cross-section as a typical section, the inner layer of the cylinder is a shell, and the outer layer is an anti-collision structure. The shell and the anti-collision structure are seamlessly nested and connected as a whole through N steel skeletons, integrating the protective function into the containment of a single item, which can save cost and facilitate construction. The anti-collision structure is distributed on the outside of the shell, formed as a whole by the steel skeleton, and connected to the prestressed reinforced concrete shell. This impact-resistant containment structure enables the traditional prestressed reinforced concrete containment to have a strong ability to resist aircraft impact. For another example, CN222276335U discloses an explosion-proof vibration-damping energy-absorbing wall structure, comprising a base wall panel body, the surface of which is provided with a reinforcement component; a reinforcement component is provided on this device, and when in use, a precast concrete layer is poured between two base wall panel bodies, and an elastic steel plate is provided between the precast concrete layers to improve the energy absorption effect of the wall, a plurality of protrusions are installed on the surface of the elastic steel plate, a gap is left between the cast precast concrete layers, and a viscoelastic damping material is poured between the two cast precast concrete layers to improve the seismic and shock-absorbing performance of the wall, and the installation component is cooperated to install the precast concrete block in the installation frame, and a card block is installed on the surface of the installation frame and a card slot is opened on the other side, the card block on one installation frame is clamped into the card slot opened on the surface of the other installation frame, and the two installation frames are fixed to each other by fixing bolts b, which is convenient for assembling the wall and easy to install.

[0004] However, these existing protective structures fail to completely solve the above problems, and there is no corresponding structural design method. Summary of the invention

[0005] The purpose of this application is to solve the above-mentioned technical problems, in order to ensure that the protective structure of the nuclear power plant has good impact resistance, while greatly reducing the cross-sectional thickness of the protective structure, achieving effects such as lightweight structure and simplified construction.

[0006] To achieve the above-mentioned objectives, the first aspect of the present application proposes a steel plate composite concrete protective structure, comprising an outer steel plate, a foam energy absorption layer, and a concrete layer, wherein the outer steel plate is located at the outermost side of the protective structure, the foam energy absorption layer is located on the inner side of the outer steel plate, and the concrete layer is located further inside the protective structure than the foam energy absorption layer.

[0007] Furthermore, the foam energy absorbing layer is in direct contact with the outer steel plate.

[0008] Furthermore, it also includes a reinforcing rib, one end of which is connected to the outer steel plate, and the reinforcing rib is located in the foam energy absorbing layer.

[0009] Furthermore, the reinforcing rib is a T-shaped reinforcing rib.

[0010] Furthermore, the material of the concrete layer is high-ductility concrete with a fiber content of 2-3% by volume.

[0011] Furthermore, it also includes a perforated metal plate, the foam energy absorbing layer is located on the outer side of the perforated metal plate, and the concrete layer is located on the inner side of the perforated metal plate.

[0012] Furthermore, the perforated metal plate further comprises an elastic material, and the elastic material is filled in the holes of the perforated metal plate.

[0013] Furthermore, it also includes a flexible metal mesh, which is located on the outer side of the perforated metal plate and the inner side of the foam energy absorbing layer.

[0014] Furthermore, the flexible metal mesh is in direct contact with the perforated metal plate and the foam energy absorbing layer respectively.

[0015] Furthermore, it also includes a tie rod, one end of which is connected to the perforated metal plate, and the other end of which is connected to the concrete layer.

[0016] Furthermore, the concrete layer also includes an anchor block, and the reinforcement is connected to the anchor block.

[0017] Furthermore, the anchor block is located at one end where the reinforcement is connected to the concrete layer, the anchor block and the reinforcement are welded or mechanically connected, and the anchor block is located in the concrete layer.

[0018] Furthermore, it also includes an inner steel plate, which is located at the innermost side of the protective structure, and the concrete layer is located at a relatively outer side of the protective structure compared to the inner steel plate.

[0019] Furthermore, it also includes a reinforcing rib, one end of which is connected to the inner steel plate, and the reinforcing rib is located in the concrete layer.

[0020] Furthermore, the reinforced ribs are T-shaped reinforced ribs.

[0021] To achieve the above-mentioned purpose, the second aspect of the present application proposes a design method for a protective structure, which is used for designing the steel plate composite concrete protective structure.

[0022] The method comprises the steps of: determining the maximum impact energy that the protective structure needs to withstand;

[0023] Step 2: determining the total energy that the protective structure can absorb, the total energy that the protective structure can absorb includes the energy that the outer steel plate can absorb, the energy that the foam energy-absorbing layer can absorb, and the energy that the concrete layer can absorb.

[0024] Step three, compare the maximum impact energy that the protective structure needs to withstand with the total energy that the protective structure can absorb. If the total energy that the protective structure can absorb is greater than or equal to the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure meets the design requirements. If the total energy that the protective structure can absorb is less than the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure does not meet the design requirements, and the design parameters are readjusted and recalculated.

[0025] Furthermore, the energy absorbed by the foam energy absorbing layer is calculated based on the stress-strain relationship of the foam energy absorbing material.

[0026] Furthermore, the calculation formula of the energy absorbed by the foam energy absorbing layer can be expressed as follows:

[0027]

[0028] Among them, E f The energy absorbed by the foam energy absorbing layer, V1 is the volume of the foam energy absorbing layer, ε f is the unit strain of the foam energy absorbing layer, σ f is the unit stress of the foam energy absorbing layer.

[0029] Furthermore, the calculation formula for the energy that can be absorbed by the outer steel plate is as follows:

[0030]

[0031] In the formula, E outs is the energy that the outer steel plate (1) can absorb, M is the mass of the projectile, σ sy1 is the yield strength of the outer steel plate, ρ s is the density of the outer steel plate, H s is the thickness of the outer steel plate, d is the diameter of the projectile, N1 and N2 are the geometric parameters of the projectile warhead. For aircraft engines, flat-head bullet parameters can be used, and N1=1 and N2=1 are taken. A and B are dimensionless material parameters of the steel plate. The steel plate is a strain-hardened material, and the value range of B is 0.9-1.3. A can be calculated using the following formula:

[0032]

[0033] Where E s is the elastic modulus of the steel plate, n is the strain hardening exponent, b and f(x) are given by the following formula:

[0034]

[0035] Furthermore, the calculation formula for the energy that the concrete layer can absorb is as follows:

[0036]

[0037] In the formula, E c is the energy that the concrete layer can absorb, f c is the axial compressive strength of concrete (MPa); b e is the distance from the loading boundary h c / 2 is the critical circumference (mm); h c is the concrete section height (mm); k c It is the amplification factor of the fiber bonding effect in concrete, and its value range is 1.1 to 1.3; α is the adjustment coefficient, and its value range is 0.6 to 1.0.

[0038] Furthermore, the protective structure also includes the perforated metal plate, and the total energy that can be absorbed by the protective structure also includes the energy that can be absorbed by the perforated metal plate.

[0039] Furthermore, the energy that the perforated metal plate can absorb is calculated by integrating the stress-strain curve, and the calculation formula is as follows:

[0040]

[0041] In the formula, E Al The energy absorbed by the perforated metal plate, V2 is the volume of the perforated metal plate, ε Al is the unit strain of the perforated metal plate, σ Alis the unit stress of the perforated metal plate.

[0042] Furthermore, the protective structure also includes the inner steel plate, and the total energy that can be absorbed by the protective structure also includes the energy that can be absorbed by the inner steel plate in an elastic state.

[0043] Furthermore, the calculation formula for the energy that the inner steel plate can absorb in the elastic state is as follows:

[0044]

[0045] In the formula, E ins is the energy that the inner steel plate can absorb in the elastic state, σ sy2 is the yield strength of the inner steel plate, ε sy2 is the strain of the inner steel plate when it yields, V s2 is the volume of the inner steel plate.

[0046] By applying the above technical solution of the present invention, at least the following technical effects are achieved:

[0047] 1. The steel plate composite concrete protection structure provides a multi-layer protection mechanism, wherein the designed outer steel plate can reduce the speed of the protective projectiles that hit the nuclear power plant and dissipate a large amount of energy, while also reducing the energy input of the shock wave and blocking a portion of the hard / soft projectiles to form the first layer of protection; the designed foam energy-absorbing layer not only reduces the dead weight of the protective structure, but also relies on the large deformation of the material itself to absorb the impact energy to form the second layer of protection, and prolongs the propagation time of the shock wave in the multi-layer protection structure, thereby gaining more reaction time for the nuclear power plant personnel and equipment operations; the designed concrete layer can block the projectiles that pass through the previous protective layer to form a protective layer.

[0048] 2. The designed flexible metal mesh can intercept the missiles that pass through the foam energy-absorbing layer, thus playing the role of the third layer of interception protection; the designed perforated metal plate can absorb external impact energy, block the missiles that pass through the foam energy-absorbing layer, and expand the propagation area of ​​the impact force brought by the missiles, so that the damage form of the concrete layer changes when it is impacted, thus forming the fourth layer of protection; the designed inner steel plate can not only block the missiles that pass through the concrete layer and absorb energy, but also protect the back of the concrete layer from being broken and peeled off after the impact, thus ensuring that the items inside the protection are not affected, while preventing the radioactive materials inside the nuclear power plant from leaking into the external environment.

[0049] 3. The reinforced ribs designed on the outer steel plate are used to connect the outer steel plate with the foam energy-absorbing layer, and the reinforced ribs designed on the inner steel plate are used to connect the inner steel plate with the concrete layer. The designed T-shaped reinforced ribs improve the connection capacity between the outer steel plate and the foam energy-absorbing layer, and between the inner steel plate and the concrete layer; the designed tension bars are used to connect the perforated metal plate and the concrete layer, and the designed anchor blocks improve the anchoring force between the tension bars and the concrete layer.

[0050] 4. A design method for a protective structure is proposed. The calculation formula fully considers the effect of high-ductility concrete and can be modified and adjusted according to actual conditions, which is more in line with actual conditions. The size and shape of the outer steel plate, foam energy absorption layer, concrete layer and other components in the protective structure can be flexibly adjusted according to actual protection needs and factors such as the shape of the building.

[0051] 5. The proposed formulas for calculating the energy absorbed by the foam energy-absorbing layer, the energy absorbed by the outer steel plate, the energy absorbed by the concrete layer, the energy absorbed by the perforated metal plate, and the energy absorbed by the inner steel plate in an elastic state make the design method more accurate, improve the utilization efficiency of materials, and reduce the project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0053] Figure 1 A structural diagram of a steel plate composite concrete protective structure in one embodiment is presented;

[0054] Figure 2 A design flow chart of a steel plate composite concrete protective structure in one embodiment is presented.

[0055] Figure numerals: 1. outer steel plate; 2. foam energy-absorbing layer; 3. perforated metal plate; 4. concrete layer; 5. inner steel plate; 6. flexible metal mesh; 7. reinforced rib; 8. anchor block. DETAILED DESCRIPTION

[0056] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0057] The present invention is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention.

[0058] Example 1

[0059] According to one aspect of the present application, this embodiment proposes a steel plate composite concrete protective structure, including an outer steel plate 1, a foam energy absorption layer 2, and a concrete layer 4. The outer steel plate 1 is located at the outermost side of the protective structure, the foam energy absorption layer 2 is located on the inner side of the outer steel plate 1, and the concrete layer 4 is located at a position further inside the protective structure than the foam energy absorption layer 2.

[0060] Specifically, the structure also includes a reinforced rib 7, one end of which is connected to the outer steel plate, and the reinforced rib 7 is located in the foam energy absorbing layer 2. The foam energy absorbing layer 2 is in direct contact with the outer steel plate 1. The reinforced rib 7 is a T-shaped reinforcing rib, wherein the outer steel plate 1 is anchored to the foam energy absorbing layer 2 through the T-shaped reinforced rib. The thickness of the outer steel plate 1 is preferably 6mm to 14mm. When the thickness of the outer steel plate is within this range, it can ensure a certain strength and rigidity to resist the impact of projectiles, reduce the impact speed and dissipate energy, and will not make the structure's own weight too large. The spacing between the T-shaped reinforced ribs must ensure that there is no connection failure between the outer steel plate 1 and the foam energy absorbing layer 2.

[0061] According to another aspect of the present application, this implementation proposes a design method for a protective structure, which is used for the design of the steel plate composite concrete protective structure, including step one, determining the maximum impact energy that the protective structure needs to withstand, step two, determining the total energy that the protective structure can absorb, the total energy that the protective structure can absorb includes the energy that the outer steel plate 1 can absorb, the energy that the foam energy-absorbing layer 2 can absorb, and the energy that the concrete layer 4 can absorb, and step three, comparing the maximum impact energy that the protective structure needs to withstand with the total energy that the protective structure can absorb, if the total energy that the protective structure can absorb is greater than or equal to the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure meets the design requirements, if the total energy that the protective structure can absorb is less than the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure does not meet the design requirements, and the design parameters are readjusted and recalculated.

[0062] Specifically, determine the maximum impact energy E that the protective structure needs to withstand k , calculate the external impact energy based on the mass M of the missile and the impact velocity v of the missile

[0063] Calculate the energy E absorbed by the outer steel plate when hit by a missile outs , the calculation formula of the energy that the outer steel plate 1 can absorb is as follows:

[0064]

[0065] In the formula, E outsis the energy that the outer steel plate (1) can absorb, M is the mass of the projectile, σ sy1 is the yield strength of the outer steel plate, ρ s is the density of the outer steel plate, H s is the thickness of the outer steel plate, d is the diameter of the projectile, N1 and N2 are the geometric parameters of the projectile warhead. For aircraft engines, the flat-head bullet parameters can be used, taking N1=1 and N2=1. For egg-headed bullets, N1 is between 0.8 and 1.2, and N2 is between 0.9 and 1.1; for cone-headed bullets, N1 is between 0.6 and 1.0, and N2 is between 0.7 and 0.9; for truncated egg-headed bullets, N1 is between 0.7 and 1.1, and N2 is between 0.8 and 1.0; for blunt-headed bullets, N1 is between 0.9 and 1.3, and N2 is between 0.95 and 1.15. A and B are dimensionless material parameters of the steel plate. The steel plate is a strain-hardened material. The value range of B is 0.9 to 1.3. A can be calculated using the following formula:

[0066]

[0067] Where E s is the elastic modulus of the steel plate, n is the strain hardening exponent, b and f(x) are given by the following formula:

[0068]

[0069] Calculate the energy E absorbed by the foam energy-absorbing layer when it is hit by a projectile f The energy absorbed by the foam energy absorbing layer 2 is calculated based on the stress-strain relationship of the foam energy absorbing material. The calculation formula of the energy absorbed by the foam energy absorbing layer 2 can be expressed as follows:

[0070]

[0071] Among them, Ef 所 The energy absorbed by the foam energy absorbing layer 2, V1 is the volume of the foam energy absorbing layer 2, ε f is the unit strain of the foam energy absorbing layer 2, σ f is the unit stress of the foam energy absorbing layer 2.

[0072] In the preferred embodiment, the concrete layer 4 is made of high ductility concrete. The energy E absorbed by the concrete layer 4 under the impact of the projectile is calculated. c , the calculation formula of the energy that the concrete layer 4 can absorb is as follows:

[0073]

[0074] In the formula, E c is the energy that the concrete layer 4 can absorb, f cis the axial compressive strength of concrete (MPa); b e is the distance from the loading boundary h c / 2 is the critical circumference (mm); h c is the concrete section height (mm); k c It is the amplification factor of the fiber bonding effect in concrete, and its value range is 1.1 to 1.3; α is the adjustment coefficient, and its value range is 0.6 to 1.0.

[0075] Calculate the total energy E that the protective wall can absorb p , that is, E p =E out +E f +E c , and with E k For comparison, if E p >E k , then the protective wall design meets the requirements; if E p <E k , then readjust the material thickness and design parameters of each part and repeat the above calculations until the requirements are met.

[0076] By applying the above technical solution of the present invention, at least the following technical effects are achieved:

[0077] 1. The steel plate composite concrete protection structure provides a multi-layer protection mechanism, wherein the designed outer steel plate can reduce the speed of the protective projectiles that hit the nuclear power plant and dissipate a large amount of energy, while also reducing the energy input of the shock wave and blocking a portion of the hard / soft projectiles to form the first layer of protection; the designed foam energy-absorbing layer not only reduces the dead weight of the protective structure, but also relies on the large deformation of the material itself to absorb the impact energy to form the second layer of protection, and prolongs the propagation time of the shock wave in the multi-layer protection structure, thereby gaining more reaction time for the nuclear power plant personnel and equipment operations; the designed concrete layer can block the projectiles that pass through the previous protective layer to form a protective layer.

[0078] 2. A design method for a protective structure is proposed. The calculation formula fully considers the effect of high-ductility concrete and can be modified and adjusted according to actual conditions, which is more in line with actual conditions. The size and shape of the outer steel plate, foam energy absorption layer, concrete layer and other components in the protective structure can be flexibly adjusted according to actual protection needs and factors such as the shape of the building.

[0079] 3. The proposed calculation formulas for the energy absorbed by the foam energy-absorbing layer, the energy absorbed by the outer steel plate, and the energy absorbed by the concrete layer make the design method more accurate, improve the utilization efficiency of materials, and reduce the project cost.

[0080] Example 2

[0081] According to one aspect of the present application, this embodiment proposes a steel plate composite concrete protective structure, including an outer steel plate 1, a foam energy absorption layer 2, and a concrete layer 4. The outer steel plate 1 is located at the outermost side of the protective structure, the foam energy absorption layer 2 is located on the inner side of the outer steel plate 1, and the concrete layer 4 is located at a position further inside the protective structure than the foam energy absorption layer 2.

[0082] The structure also includes a reinforcing rib 7. Specifically, one end of the reinforcing rib 7 is connected to the outer steel plate. The reinforcing rib 7 is located in the foam energy absorbing layer 2. The foam energy absorbing layer 2 is in direct contact with the outer steel plate 1. The reinforcing rib 7 is a T-shaped reinforcing rib, wherein the outer steel plate 1 is anchored to the foam energy absorbing layer 2 through the T-shaped reinforcing rib. The thickness of the outer steel plate 1 is preferably 6 mm to 14 mm. When the thickness of the outer steel plate is within this range, it can ensure a certain strength and rigidity to resist the impact of projectiles, reduce the impact speed and dissipate energy, and will not make the structure's own weight too large. The spacing between the T-shaped reinforcing ribs must ensure that there is no connection failure between the outer steel plate 1 and the foam energy absorbing layer 2.

[0083] The foam energy absorbing layer is made of foam materials such as polyurethane foam and foam aluminum. Specifically, the thickness of the foam energy absorbing layer is preferably 80 mm to 250 mm.

[0084] The material of the concrete layer 4 is a high-ductility concrete with a volume percentage of 2-3% of fiber content. Specifically, the high-ductility concrete, Engineered Cementitious Composites (ECC), is a fiber-reinforced composite material based on the design principle of micromechanics and based on cement, quartz sand, etc. It is a new type of structural material with high toughness, high crack resistance and good damage resistance. It has the characteristics of multiple crack development and strain hardening under tensile and shear loads, which can significantly improve the toughness and crack resistance of concrete materials. Also known as "bendable concrete", unlike ordinary fiber concrete, ECC exhibits a metal-like strain hardening phenomenon when subjected to tension, and its ultimate tensile strain reaches 3% to 7%, which is about 300 to 500 times that of ordinary (fiber) concrete; during the stretching process, the surface of the specimen shows a multi-crack cracking phenomenon, and the crack width is less than 100μm, which can significantly improve the deformation capacity of the component and absorb more energy when damaged. At the same time, relevant research literature also shows that ECC components have good impact resistance.

[0085] Specifically, the mixed fibers may be metal fibers, inorganic fibers, organic fibers, etc., and the concrete layer may be configured with a small amount or no other stress-bearing steel bars in the structure according to demand.

[0086] The protective structure also includes a porous metal plate 3, the foam energy absorbing layer 2 is located on the outside of the porous metal plate 3, and the concrete layer 4 is located on the inside of the porous metal plate 3. Specifically, the porous metal plate is a honeycomb metal plate, such as an aluminum honeycomb plate, a titanium alloy honeycomb plate, etc. The honeycomb metal plate has a regular hexagonal pore structure, which can effectively disperse stress when subjected to impact and explosion loads, and absorb energy through deformation and crushing of the pore wall. The thickness of the honeycomb metal plate can be determined according to actual needs, and the preferred thickness is within the thickness range of 60 mm to 300 mm. The honeycomb metal plate and the foam energy absorbing layer are connected by a special connection method, such as a combination of bonding and mechanical connection.

[0087] The perforated metal plate 3 further comprises an elastic material, and the elastic material is filled in the holes of the perforated metal plate 3 to improve the strength of the honeycomb metal plate. Specifically, the elastic material is a lightweight elastic material.

[0088] The protective structure further includes a flexible metal mesh 6, which is located on the outside of the perforated metal plate 3 and the inside of the foam energy absorbing layer 2, and the flexible metal mesh 6 is in direct contact with the perforated metal plate 3 and the foam energy absorbing layer 2. Specifically, the flexible metal mesh is bonded to the foam energy absorbing layer by a bonding material such as a universal glue.

[0089] The protective structure also includes a tie bar, one end of which is connected to the perforated metal plate 3, and the other end of which is connected to the concrete layer 4. The concrete layer 4 also includes an anchor block 8. The tie bar is connected to the anchor block 8, and the anchor block 8 is located at the end of the tie bar connected to the concrete layer 4. The anchor block 8 is welded or mechanically connected to the tie bar, and the anchor block 8 is located in the concrete layer 4. Specifically, the tie bar is welded to the honeycomb metal plate, and the anchor block is welded to the end of the tie bar. The tie bar should be made of high-strength hot-rolled ribbed steel bars, such as HRB400 grade, and the anchor block is made of the same material as the tie bar.

[0090] The protective structure also includes an inner steel plate 5 and a reinforced rib 7. The inner steel plate 5 is located at the innermost side of the protective structure. The concrete layer 4 is located at a relatively outer side of the protective structure compared to the inner steel plate 5. One end of the reinforced rib 7 is connected to the inner steel plate 5. The reinforced rib 7 is located in the concrete layer 4. The reinforced rib 7 is a T-shaped reinforced rib. Specifically, the inner steel plate is connected to the concrete layer through a T-shaped reinforced rib plate. The T-shaped reinforced ribs are evenly arranged and welded on the inner steel plate. The length of the T-shaped reinforced rib extending into the concrete layer needs to ensure that the two are effectively anchored and connected. The inner surface of the inner steel plate is treated with anti-corrosion and fireproofing.

[0091] In the actual construction process, the inner and outer steel plates can be used as construction templates for the protective structure of the nuclear power plant, the T-shaped stiffening ribs 7 can be welded to the inner and outer steel plates in the factory or on site, the tie bars 8 can be welded to the outer steel plate 1 in the factory or on site, and the anchor blocks 8 can be welded to the tie bars 8 in the factory or on site. The tie bars 8 and the T-shaped stiffening ribs 7 are staggered and are not arranged at the same horizontal position; the inner and outer steel plates can be used to support the template, and the foam energy absorption layer is provided with openings according to the arrangement of the stiffening ribs. During installation, the T-shaped stiffening ribs 7 pass through the foam energy absorption layer 2. After the foam energy absorption layer 2 is arranged and fixed in position, a flexible metal mesh 6 coated with an adhesive is placed to bond with the foam energy absorption layer 2, and the flexible metal mesh 6 is bonded to the aluminum honeycomb layer 3 by an adhesive, and finally high-ductility concrete 4 is poured to form an integral steel plate composite concrete protective structure.

[0092] According to another aspect of the present application, this implementation proposes a design method for a protective structure, which is used for the design of the steel plate composite concrete protective structure, including step one, determining the maximum impact energy that the protective structure needs to withstand, step two, determining the total energy that the protective structure can absorb, the total energy that the protective structure can absorb includes the energy that the outer steel plate 1 can absorb, the energy that the foam energy-absorbing layer 2 can absorb, and the energy that the concrete layer 4 can absorb, and step three, comparing the maximum impact energy that the protective structure needs to withstand with the total energy that the protective structure can absorb, if the total energy that the protective structure can absorb is greater than or equal to the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure meets the design requirements, if the total energy that the protective structure can absorb is less than the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure does not meet the design requirements, and the design parameters are readjusted and recalculated.

[0093] Specifically, determine the maximum impact energy E that the protective structure needs to withstand k , calculate the external impact energy based on the mass M of the missile and the impact velocity v of the missile

[0094] Calculate the energy E absorbed by the outer steel plate when hit by a missile outs , the calculation formula of the energy that the outer steel plate 1 can absorb is as follows:

[0095]

[0096] In the formula, E outs is the energy that the outer steel plate 1 can absorb, M is the mass of the projectile, σ sy1 is the yield strength of the outer steel plate, ρ s is the density of the outer steel plate, H sis the thickness of the outer steel plate, d is the diameter of the projectile, N1 and N2 are the geometric parameters of the projectile warhead, for aircraft engines, flat-head bullet parameters can be used, taking N1=1, N2=1, for egg-headed bullets, N1 is between 0.8 and 1.2, N2 is between 0.9 and 1.1; for cone-headed bullets, N1 is between 0.6 and 1.0, N2 is between 0.7 and 0.9; for truncated egg-headed bullets, N1 is between 0.7 and 1.1, N2 is between 0.8 and 1.0; for blunt-headed bullets, N1 is between 0.9 and 1.3, N2 is between 0.95 and 1.15, A and B are dimensionless material parameters of the steel plate, the steel plate is a strain-hardened material, B has a value range of 0.9 to 1.3, and A can be calculated using the following formula:

[0097]

[0098] Where E s is the elastic modulus of the steel plate, n is the strain hardening exponent, b and f(x) are given by the following formula:

[0099]

[0100] Calculate the energy E absorbed by the foam energy-absorbing layer when it is hit by a projectile f The energy absorbed by the foam energy absorbing layer 2 is calculated based on the stress-strain relationship of the foam energy absorbing material. The calculation formula of the energy absorbed by the foam energy absorbing layer 2 can be expressed as follows:

[0101]

[0102] Among them, E f The energy absorbed by the foam energy absorbing layer 2, V1 is the volume of the foam energy absorbing layer 2, ε f is the unit strain of the foam energy absorbing layer 2, σ f is the unit stress of the foam energy absorbing layer 2.

[0103] Calculate the energy E absorbed by the concrete layer 4 when the missile hits it c , the calculation formula of the energy that the concrete layer 4 can absorb is as follows:

[0104]

[0105] In the formula, E c is the energy that the concrete layer 4 can absorb, f c is the axial compressive strength of concrete (MPa; b e is the distance from the loading boundary h c / 2 is the critical circumference (mm); h c is the concrete section height (mm); k cIt is the amplification factor of the fiber bonding effect in concrete, and its value range is 1.1 to 1.3; α is the adjustment coefficient, and its value range is 0.6 to 1.0.

[0106] The protection structure further comprises the perforated metal plate 3 , and the total energy that can be absorbed by the protection structure also comprises the energy that can be absorbed by the perforated metal plate 3 .

[0107] Calculate the energy E absorbed by the perforated metal plate 3 when the projectile hits it Al The energy that the perforated metal plate 3 can absorb is calculated by integrating the stress-strain curve, and the calculation formula is as follows:

[0108]

[0109] In the formula, E Al The energy absorbed by the perforated metal plate 3, C2 is the volume of the perforated metal plate 3, ε Al is the unit strain of the perforated metal plate 3, σ Al is the unit stress of the perforated metal plate 3.

[0110] The protective structure also includes the inner steel plate 5 , and the total energy that can be absorbed by the protective structure also includes the energy that can be absorbed by the inner steel plate 5 in an elastic state.

[0111] Calculate the energy E absorbed by the inner steel plate in the elastic state ins , the calculation formula of the energy that the inner steel plate 5 can absorb in the elastic state is as follows:

[0112]

[0113] In the formula, E ins is the energy that the inner steel plate 5 can absorb in the elastic state, σ sy2 is the yield strength of the inner steel plate, ε sy2 is the strain of the inner steel plate when it yields, V s2 is the volume of the inner steel plate.

[0114] Calculate the total energy E that the protective wall can absorb p , that is, E p =E out +E f +E Al +E c +E ins , and with E k For comparison, if E p >E k , then the protective wall design meets the requirements; if E p <E k, then readjust the material thickness and design parameters of each part and repeat the above calculations until the requirements are met.

[0115] By applying the above technical solution of the present invention, at least the following technical effects are achieved:

[0116] 1. The steel plate composite concrete protection structure provides a multi-layer protection mechanism, wherein the designed outer steel plate can reduce the speed of the protective projectiles that hit the nuclear power plant and dissipate a large amount of energy, while also reducing the energy input of the shock wave and blocking a portion of the hard / soft projectiles to form the first layer of protection; the designed foam energy-absorbing layer not only reduces the dead weight of the protective structure, but also relies on the large deformation of the material itself to absorb the impact energy to form the second layer of protection, and prolongs the propagation time of the shock wave in the multi-layer protection structure, thereby gaining more reaction time for the nuclear power plant personnel and equipment operations; the designed concrete layer can block the projectiles that pass through the previous protective layer to form a protective layer.

[0117] 2. The designed flexible metal mesh can intercept the missiles that pass through the foam energy-absorbing layer, thus playing the role of the third layer of interception protection; the designed perforated metal plate can absorb external impact energy, block the missiles that pass through the foam energy-absorbing layer, and expand the propagation area of ​​the impact force brought by the missiles, so that the damage form of the concrete layer changes when it is impacted, thus forming the fourth layer of protection; the designed inner steel plate can not only block the missiles that pass through the concrete layer and absorb energy, but also protect the back of the concrete layer from being broken and peeled off after the impact, thus ensuring that the items inside the protection are not affected, while preventing the radioactive materials inside the nuclear power plant from leaking into the external environment.

[0118] 3. The reinforced ribs designed on the outer steel plate are used to connect the outer steel plate with the foam energy-absorbing layer, and the reinforced ribs designed on the inner steel plate are used to connect the inner steel plate with the concrete layer. The designed T-shaped reinforced ribs improve the connection capacity between the outer steel plate and the foam energy-absorbing layer, and between the inner steel plate and the concrete layer; the designed tension bars are used to connect the perforated metal plate and the concrete layer, and the designed anchor blocks improve the anchoring force between the tension bars and the concrete layer.

[0119] 4. High-ductility concrete with a fiber content of 2%-3% by volume has excellent material properties, and can be equipped with little or no stress-bearing steel bars, which greatly reduces the steel reinforcement ratio and avoids complex construction. It is also convenient for modular construction and greatly shortens the construction period. Honeycomb metal panels can further absorb energy and buffer. When the shock wave passes through the honeycomb metal panel, the area of ​​the shock wave is dispersed and expanded to a larger range, so that the area acting on the concrete layer is increased, thereby changing the destruction mode of the concrete from local destruction to overall destruction. It can be considered that after passing through the honeycomb metal panel, the area of ​​the force acting on the concrete layer by the projectile is expanded by 10 to 20 times the diameter of the projectile.

[0120] 5. A design method for a protective structure is proposed. The calculation formula fully considers the effect of high-ductility concrete and can be modified and adjusted according to actual conditions, which is more in line with actual conditions. The size and shape of the outer steel plate, foam energy absorption layer, concrete layer and other components in the protective structure can be flexibly adjusted according to actual protection needs and factors such as the shape of the building.

[0121] 6. The proposed formulas for calculating the energy absorbed by the foam energy-absorbing layer, the energy absorbed by the outer steel plate, the energy absorbed by the concrete layer, the energy absorbed by the perforated metal plate, and the energy absorbed by the inner steel plate in an elastic state make the design method more accurate, improve the utilization efficiency of materials, and reduce the project cost.

[0122] The above are only a number of specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0123] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0124] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

Claims

1. A steel plate composite concrete protective structure, characterized in that: The protective structure comprises an outer steel plate (1), a foam energy absorbing layer (2), and a concrete layer (4), wherein the outer steel plate (1) is located at the outermost side of the protective structure, the foam energy absorbing layer (2) is located at the inner side of the outer steel plate (1), and the concrete layer (4) is located at a position further inside the protective structure than the foam energy absorbing layer (2).

2. The steel plate composite concrete protective structure according to claim 1, characterized in that: The foam energy absorbing layer (2) is in direct contact with the outer steel plate (1).

3. The steel plate composite concrete protective structure according to claim 1, characterized in that: It also includes a reinforcing rib (7), one end of which is connected to the outer steel plate, and the reinforcing rib (7) is located in the foam energy absorbing layer (2).

4. The steel plate composite concrete protective structure according to claim 3, characterized in that: The reinforcing rib (7) is a T-shaped reinforcing rib.

5. The steel plate composite concrete protective structure according to claim 1, characterized in that: The material of the concrete layer (4) is high-ductility concrete with a fiber content of 2-3% by volume.

6. The steel plate composite concrete protective structure according to claim 1, characterized in that: It also comprises a perforated metal plate (3), the foam energy absorbing layer (2) is located on the outside of the perforated metal plate (3), and the concrete layer (4) is located on the inside of the perforated metal plate (3).

7. The steel plate composite concrete protective structure according to claim 6, characterized in that: The perforated metal plate (3) further comprises an elastic material, wherein the elastic material is filled in the holes of the perforated metal plate (3).

8. The steel plate composite concrete protective structure according to claim 6, characterized in that: It also comprises a flexible metal mesh (6), wherein the flexible metal mesh (6) is located on the outside of the perforated metal plate (3), and the flexible metal mesh (6) is located on the inside of the foam energy absorbing layer (2).

9. The steel plate composite concrete protective structure according to claim 8, characterized in that: The flexible metal mesh (6) is in direct contact with the perforated metal plate (3) and the foam energy absorbing layer (2) respectively.

10. The steel plate composite concrete protective structure according to claim 6, characterized in that: It also comprises a tie rod, one end of which is connected to the perforated metal plate (3), and the other end of which is connected to the concrete layer (4).

11. The steel plate composite concrete protective structure according to claim 10, characterized in that: The concrete layer (4) further comprises an anchor block (8), and the reinforcement is connected to the anchor block (8).

12. The steel plate composite concrete protective structure according to claim 11, characterized in that: The anchor block (8) is located at one end of the reinforcement connected to the concrete layer (4); the anchor block (8) and the reinforcement are connected by welding or mechanical connection; and the anchor block (8) is located in the concrete layer (4).

13. The steel plate composite concrete protective structure according to claim 1, characterized in that: It also includes an inner steel plate (5), wherein the inner steel plate (5) is located at the innermost side of the protective structure, and the concrete layer (4) is located at a position on the outer side of the protective structure compared to the inner steel plate (5).

14. The steel plate composite concrete protective structure according to claim 13, characterized in that: It also includes a reinforcing rib (7), one end of which is connected to the inner steel plate (5), and the reinforcing rib (7) is located in the concrete layer (4).

15. The steel plate composite concrete protective structure according to claim 14, characterized in that: The reinforced rib (7) is a T-shaped reinforced rib.

16. A protective structure design method, used for designing the steel plate composite concrete protective structure according to claim 1, characterized in that: The method comprises the steps of: determining the maximum impact energy that the protective structure needs to withstand; Step 2: determining the total energy that the protective structure can absorb, the total energy that the protective structure can absorb includes the energy that the outer steel plate (1) can absorb, the energy that the foam energy absorbing layer (2) can absorb, and the energy that the concrete layer (4) can absorb. Step three, compare the maximum impact energy that the protective structure needs to withstand with the total energy that the protective structure can absorb. If the total energy that the protective structure can absorb is greater than or equal to the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure meets the design requirements. If the total energy that the protective structure can absorb is less than the maximum impact energy that the protective structure needs to withstand, then the steel plate composite concrete protective structure does not meet the design requirements, and the design parameters are readjusted and recalculated.

17. A protective structure design method according to claim 16, characterized in that: The energy absorbed by the foam energy absorbing layer (2) is calculated based on the stress-strain relationship of the foam energy absorbing material.

18. A protective structure design method according to claim 17, characterized in that: The calculation formula of the energy absorbed by the foam energy absorbing layer (2) can be expressed as follows: Among them, E f The energy absorbed by the foam energy absorbing layer (2), V1 is the volume of the foam energy absorbing layer (2), ε f is the unit strain of the foam energy absorbing layer (2), σ f is the unit stress of the foam energy absorbing layer (2).

19. A protective structure design method according to claim 16, characterized in that: The calculation formula of the energy that the outer steel plate (1) can absorb is as follows: In the formula, E outs is the energy that the outer steel plate (1) can absorb, M is the mass of the projectile, σ sy1 is the yield strength of the outer steel plate, ρ s is the density of the outer steel plate, H s is the thickness of the outer steel plate, d is the diameter of the projectile, N1 and N2 are the geometric parameters of the projectile warhead, A and B are dimensionless material parameters of the steel plate, the steel plate is a strain hardened material, the value range of B is 0.9 to 1.3, and A can be calculated using the following formula: Where E s is the elastic modulus of the steel plate, n is the strain hardening exponent, b and f(x) are given by the following formula:

20. A method for designing a protective structure according to claim 16, characterized in that: The calculation formula of the energy that the concrete layer (4) can absorb is as follows: In the formula, E c is the energy that the concrete layer (4) can absorb, f c is the axial compressive strength of concrete; b e is the distance from the loading boundary h c / 2 critical perimeter; h c is the concrete section height; k c It is the amplification factor of the fiber bonding effect in concrete, and its value range is 1.1 to 1.3; α is the adjustment coefficient, and its value range is 0.6 to 1.

0.

21. A protective structure design method according to claim 16, characterized in that: The protective structure also includes a perforated metal plate (3), and the total energy that can be absorbed by the protective structure also includes the energy that can be absorbed by the perforated metal plate (3).

22. A method for designing a protective structure according to claim 21, characterized in that: The energy that the perforated metal plate (3) can absorb is calculated by integrating the stress-strain curve, and the calculation formula is as follows: In the formula, E Al The energy absorbed by the perforated metal plate (3), V2 is the volume of the perforated metal plate (3), ε Al is the unit strain of the perforated metal plate (3), σ Al is the unit stress of the perforated metal plate (3).

23. A method for designing a protective structure according to claim 16, characterized in that: The protective structure also includes an inner steel plate (5), and the total energy that can be absorbed by the protective structure also includes the energy that can be absorbed by the inner steel plate (5) in an elastic state.

24. A method for designing a protective structure according to claim 23, characterized in that: The calculation formula of the energy that the inner steel plate (5) can absorb in the elastic state is as follows: In the formula, E ins is the energy that the inner steel plate (5) can absorb in the elastic state, σ sy2 is the yield strength of the inner steel plate, ε sy2 is the strain of the inner steel plate when it yields, V s2 is the volume of the inner steel plate.

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