Layered protection structure and numerical simulation method

Abstract

The invention discloses a layered protection structure and a numerical simulation method.The layered protection structure comprises a supporting structure, a camouflage layer, a bullet shielding layer and a dispersing layer, the camouflage layer is located on the uppermost portion of the layered protection structure, the bullet shielding layer is located on the lower portion of the camouflage layer, and the dispersing layer is located on the lower portion of the bullet shielding layer; and a steel plate layer is arranged between the dispersing layer and the bullet shielding layer. And the steel plate layer is an S22053 stainless steel layer with good corrosion fatigue resistance and wear corrosion resistance. Due to the fact that the steel plate layer is arranged and is made of a high-strength and high-toughness stainless steel plate, the steel plate layer has good ductility and corrosion resistance, can resist large weight and impact, and can be formed according to needs. The device is applied to civil air defense engineering to relieve explosion impact loads and is convenient to set and construct. The steel plate layer is arranged in the layered protection structure, so that the penetration impact resistance of the protection structure can be effectively improved, and a good attenuation effect can be achieved on displacement of the structure after the structure is subjected to an explosion impact load.

Description

[0001] The invention relates to a protective structure, mainly to a novel layered protective structure and a numerical simulation method, and belongs to the technical field of building protective structures. Background Art

[0002] Layered protective structures are a type of protective structure that has gradually evolved with the development of weapon technology. Before the 19th century, fortifications were mostly built with bricks and stones, which had relatively low resistance. However, as the caliber of artillery gradually increased, the original fortifications could no longer withstand the firepower of these new weapons. In order to meet this challenge, people began to use concrete and reinforced concrete to reinforce the original fortifications. In the process, they found that a layer of sand between the reinforcement layer and the original structure could reduce and prevent earthquake collapse, which formed the prototype of the layered protective structure.

[0003] A typical layered protection structure is mainly composed of a protective layer and a supporting structure. The protective layer can be divided into a camouflage layer, a bullet-proof layer and a distribution layer. Camouflage layer (covering layer): usually composed of a natural soil layer, mainly plays the role of camouflaging the lower structure. Its thickness is moderate and should not be too thick to avoid increasing the blocking effect of conventional weapon explosions. Bullet-proof layer (bullet-proof layer): usually composed of hard materials such as concrete and reinforced concrete, which plays the role of resisting the impact of conventional weapons and forcing them to explode in this layer. The bullet-proof layer should be constructed to ensure that it will not be penetrated by conventional weapons. Distribution layer (dispersion layer): composed of sand and dry loose soil, it can disperse the impact of weapons and the effects of blast loads to a larger area, and also plays a shock-absorbing role. The supporting structure is the main part of the layered protection project, generally constructed with reinforced concrete. It can withstand the overall effect of conventional weapon explosions and the compression wave in the soil caused by the shock wave of nuclear explosions.

[0004] At present, the research mainly focuses on enhancing the anti-penetration performance against conventional weapons and the destructive effect caused by explosion compression waves, while the impact of the difficulty of the construction process on the protection effect of the layered protective structure is relatively ignored. Therefore, it is urgent to adopt a new structural form so that the layered protective structure can improve the engineering quality within a limited thickness and improve the anti-penetration ability of the layered protective structure. Summary of the invention

[0005] The purpose of the present invention is to provide a new type of layered protective structure, which can effectively improve the anti-penetration ability of the layered protective structure and reduce the cracking of the supporting structure, thereby ensuring the quality of concrete construction and greatly improving production efficiency, and shortening the construction period to the maximum extent.

[0006] The purpose of the present invention is achieved by adopting the following technical scheme: the novel layered protective structure comprises a supporting structure, a camouflage layer, a bullet-proof layer and a dispersion layer, the camouflage layer is located at the top of the layered protective structure, the bullet-proof layer is located at the bottom of the camouflage layer, the dispersion layer is located at the bottom of the bullet-proof layer, and a steel plate layer is arranged between the dispersion layer and the bullet-proof layer.

[0007] The steel plate layer is an S22053 stainless steel layer having good corrosion fatigue resistance and wear corrosion resistance.

[0008] The present invention is provided with a layer of steel plate, and the steel plate layer is made of high-strength, high-toughness stainless steel plate, which has good ductility and corrosion resistance, can withstand large weight and impact resistance, and is easy to shape according to needs. It can be applied to civil air defense projects to reduce explosion impact loads, and is convenient to set up and construct. The steel plate layer is set in the layered protective structure, which can effectively improve the anti-penetration impact performance of the protective structure, and can have a good attenuation effect on the displacement of the structure after being subjected to the explosion impact load. At the same time, according to the construction process of the layered protective structure, a steel plate layer is added to the upper part of the dispersion layer and the lower part of the bullet-proof layer, and the steel plate layer is used as the inner template for concrete pouring, which can facilitate structural construction and avoid seepage problems during concrete pouring, or problems such as insufficient filling of the dispersion layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the present invention.

[0010] Figure 2 It is a schematic diagram of the protective structure with added steel plate layer.

[0011] Figure 3 It is a schematic diagram of the layered protection structure.

[0012] Figure 4 This is the cloud map of the back damage without adding steel plate layered protection structure.

[0013] Figure 5 It is to add the back damage cloud map of the steel plate layered protection structure.

[0014] Figure 6 It is a comparison chart of displacement time history curve.

[0015] Figure 7 It is a comparison chart of pressure time history curve.

[0016] In the figure: 1. Camouflage layer, 2. Bulletproof layer, 3. Steel plate layer, 4. Dispersion layer, 5. Support structure. DETAILED DESCRIPTION

[0017] The following is a further description with reference to the accompanying drawings, embodiments and numerical simulations.

[0018] The technical solution adopted by the present invention is a layered protective structure, which includes a support structure 5, a dispersion layer 4, a bullet-shielding layer 2 and a camouflage layer 1 from the inside to the outside; a steel plate layer 3 is arranged between the dispersion layer 4 and the bullet-shielding layer 2. The bullet-shielding layer 2 is cast by ultra-high-strength concrete, the dispersion layer 4 is made of sand material, and the steel plate layer 3 is made of S22053 stainless steel layer with high toughness and good corrosion fatigue resistance. The support structure 5, the dispersion layer 4, the steel plate layer 3 and the bullet-shielding layer 2 are fixed on the bottom plate. The interior of the support structure 5 is a protective space. The camouflage layer 1 is directly laid on the bullet-shielding layer 2 to ensure that the camouflage layer 1 and the bullet-shielding layer 2 are tightly fitted.

[0019] The steel plate layer 3 is provided with upright bolts, and the bullet-proof layer 2 is provided with bolt holes at the corresponding parts of the upright bolts of the steel plate layer 3. The upright bolts and the bolt holes are fixed by nuts, so that the bullet-proof layer 2 can effectively fit closely with the steel plate layer 3 and give full play to the protective performance of the layered structure; at the same time, the steel plate layer 3 is connected to the base plate by bolts to ensure the overall strength and stability of the structure. The dispersion layer 4 is laid between the steel plate layer 3 and the supporting structure 5, and fits closely with the steel plate layer 3 and the supporting structure 5. The bullet-proof layer 2 and the supporting structure 5 are connected to the base plate by concrete pouring.

[0020] Furthermore, the steel plate layer 3 is an inner formwork for casting the bullet-proof layer 2 .

[0021] Furthermore, the cross-sectional structure of the supporting structure 5, the dispersion layer 4, the steel plate layer 3, and the bullet-proof layer 2 is an inverted U shape.

[0022] Furthermore, the camouflage layer 1 is composed of lawn and soil. The lawn can be natural grass or artificial turf, and the soil part can be natural soil or processed light soil material to increase the camouflage effect and aesthetics.

[0023] Furthermore, the bullet-proof layer 2 is made of C100 high-strength reinforced concrete mixed with steel fibers.

[0024] Furthermore, the steel plate layer 3 is made of high-strength S22053 steel and has excellent impact resistance and penetration resistance.

[0025] Furthermore, the sand material of the dispersion layer 4 is made of coarse sand with low water content.

[0026] Furthermore, the supporting structure 5 is made of C40 strength reinforced concrete.

[0027] The layered protective structure of the present invention is based on actual engineering and numerical simulation research. It utilizes the high toughness and other characteristics of high-strength S22053 steel, and sets a steel plate layer 3 between the bullet-proof layer 2 and the dispersion layer 4 to prevent the sand from collapsing when pouring the bullet-proof layer 2, and to serve as a template that does not need to be removed when pouring the bullet-proof layer 2. At the same time, it prevents concrete from seeping into the sand, which can greatly reduce the construction difficulty and effectively shorten the construction period. In terms of protective performance, it can effectively improve the explosion and penetration resistance of the protective structure, have a good attenuation effect on the peak value of the shock wave, and have a very good attenuation effect on the displacement control of the support structure 5. After the steel plate layer 3 is set, the attenuation effect of the explosion shock wave is obvious, the pressure peak on the surface of the support structure 5 is reduced by 40%, and the peak displacement of the structural layer is reduced by 47%, which reduces the generation of cracks in the support structure 5 and improves the safety and service life of the support structure 5.

[0028] like Figure 1 Shown is a schematic diagram of the layered protection structure Specific numerical calculation: The basic steps of finite element simulation are pre-processing, uploading calculation and post-processing. Each step can be processed using different software. Common pre-processing software includes ANSYS, HYPERMESH and ABAQUS, nonlinear finite element calculation software mainly includes LS-DYNA and AUTODYN, and there are many post-processing software, such as ANSYS with built-in post-processing function and LS-PREPOST and other software.

[0029] LS-DYNA software is the world's most famous general-purpose explicit dynamic analysis program. It was originally developed by Hallquist and others in the United States in 1976. After years of functional supplementation and improvement, it has gradually become the most widely used nonlinear dynamic analysis software in the world. It can simulate various complex problems in the world. It is particularly suitable for solving nonlinear dynamic impact problems such as high-speed collision, explosion and metal forming of various two-dimensional and three-dimensional nonlinear structures, and can also solve heat transfer, fluid and fluid-solid coupling problems. It is mainly based on the Lagrange algorithm, and also has ALE and Euler algorithms; it is mainly based on explicit solution, and also has implicit solution functions. It is a general-purpose structural analysis nonlinear finite element program combining industry and civil use. The structured arbitrary Lagrange Euler method used in this numerical simulation is in principle a second-order accurate advection algorithm based on the momentum conservation equation of a unified continuous medium. The interface force when the solids are in contact is obtained by the contact algorithm, which can effectively solve the problem of large displacement of the object in space and large deformation of the object itself.

[0030] The commercial finite element software LS-DYNA was used in this numerical simulation. LS-DYNA is particularly suitable for solving nonlinear dynamic impact problems such as high-speed collisions, explosions, and metal forming of various two-dimensional and three-dimensional nonlinear structures. It can also solve heat transfer, fluid, and fluid-solid coupling problems. Many scholars at home and abroad have conducted numerical simulation studies on the impact problem of ultra-high-strength concrete. The material models used include HJC, K&C, RHT, etc. The K&C model separately considers shear deformation damage and damage under triaxial tension. At the same time, by adjusting the parameters, a custom material softening curve can be obtained, and a custom dynamic enhancement coefficient curve can be separately input to consider the influence of different strain rates under compression and tension. Considering the parameter applicability of the K&C model, the K&C model was therefore used in this numerical simulation analysis.

[0031] The specific steps are as follows: a finite element model is established in LS-DYNA, the bullet-proof layer, steel plate layer, dispersion layer and structural layer are all simulated using 3D Solid164 entity units, the steel bars are simulated using beam 161 beam units, a suitable material model is selected, the boundaries are constrained, and the erosion parameters are set, an explosion load is applied to the surface of the bullet-proof layer, and a numerical analysis is carried out under explosion conditions to verify the applicability of the invented structure.

[0032] According to the numerical simulation results, Figure 4 and Figure 5 It can be concluded that the two layered protective structures in this calculation model show the greatest damage in the middle part and extend along both sides. By comparison, it can be seen that the layered protective structure with an additional steel plate layer can effectively improve the protective performance of the protective structure. Under the same working conditions, the layered protective structure with an additional steel plate layer did not suffer obvious damage, reflecting excellent protective performance.

[0033] The displacement time history curve of the structural layer is obtained by numerical simulation, such as Figure 6 As shown, curve A is the displacement time history curve of the layered protective structure with the steel plate layer added, and curve B is the displacement time history curve of the layered protective structure without the steel plate layer added. Figure 6 It can be concluded that the peak displacement of the protective structure with an additional steel plate layer is reduced by 47% compared to the protective structure without an additional steel plate layer, indicating that the steel plate layer can effectively suppress structural deformation and prevent cracking of the structural layer, which may lead to sand leakage or rust corrosion, thereby reducing the service life of the structure.

[0034] like Figure 7As shown, curve A is the pressure time-history curve of the structural layer of the layered protective structure with an added steel plate layer, and curve B is the pressure time-history curve of the structural layer of the layered protective structure without an added steel plate layer. It can be seen from the data curve in the figure that the peak pressure of the structural layer with the added steel plate layer is 4.4 MPa, which is 37% lower than the peak pressure of 7 MPa of the structural layer without the added steel plate layer, indicating that the steel plate layer can effectively weaken the impact of the explosion shock wave on the structure, so as to enhance the function of the layered protective structure.

Claims

1. A layered protective structure, comprising, from the inside to the outside, a support structure (5), a dispersion layer (4), a bullet-proof layer (2) and a camouflage layer (1); characterized in that: A steel plate layer (3) is arranged between the dispersion layer (4) and the bullet-shielding layer (2). The bullet-shielding layer (2) is cast from ultra-high-strength concrete, the dispersion layer (4) is made of sand material, and the steel plate layer (3) is made of S22053 stainless steel. The support structure (5), the dispersion layer (4), the steel plate layer (3) and the bullet-shielding layer (2) are fixed on the bottom plate. The interior of the support structure (5) is a protective space. The camouflage layer (1) is directly laid on the bullet-shielding layer (2) to ensure that the camouflage layer (1) and the bullet-shielding layer (2) are closely attached.

2. A layered protective structure according to claim 1, characterized in that: The steel plate layer (3) is provided with upright bolts, the bullet-proof layer (2) is provided with bolt holes at the portions of the steel plate layer (3) corresponding to the upright bolts, and the upright bolts and the bolt holes are fixed by nuts; the steel plate layer (3) is connected to the base plate by bolts. The dispersion layer (4) is laid between the steel plate layer (3) and the supporting structure (5), and is closely fitted to the steel plate layer (3) and the supporting structure (5). The bullet-proof layer (2) and the supporting structure (5) are both connected to the base plate by concrete pouring.

3. A layered protective structure according to claim 1, characterized in that: The steel plate layer (3) serves as an inner formwork for pouring the bullet-proof layer (2).

4. A layered protective structure according to claim 1, characterized in that: The cross-sectional structure of the support structure (5), the dispersion layer (4), the steel plate layer (3), and the bullet-proof layer (2) is an inverted U shape.

5. A layered protective structure according to claim 1, characterized in that: The camouflage layer (1) is composed of lawn and soil, the lawn is natural grass or artificial turf, and the soil is natural soil or treated light soil material.

6. A layered protective structure according to claim 1, characterized in that: The bullet-proof layer (2) is made of C100 high-strength reinforced concrete mixed with steel fibers.

7. A layered protective structure according to claim 1, characterized in that: The sand material of the dispersion layer (4) is made of coarse sand with low water content.

8. A layered protective structure according to claim 1, characterized in that: The supporting structure (5) is made of C40 strength reinforced concrete.

9. A layered protective structure according to claim 1, characterized in that: The numerical simulation method of the layered protective structure is as follows: a finite element model is established in LS-DYNA, the bullet-proof layer, steel plate layer, dispersion layer and structural layer are all simulated using 3DSolid164 solid elements, the steel bars are simulated using beam 161 beam elements, the material model is selected, the boundaries are constrained, and the erosion parameters are set. An explosion load is applied to the surface of the bullet-proof layer, and a numerical analysis is carried out under explosion conditions. The steel plate layer can effectively weaken the impact of the explosion shock wave on the structure, so as to enhance the function of the layered protective structure.

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