Hollow structure with protective structure

Abstract

To provide a hollow structure equipped with a protective structure that can mitigate the explosive impact force of a projectile on the hollow structure at a relatively low cost. [Solution] The protective structure 3 comprises an inner concrete layer 22, which is an inner hard material, provided on the side of the hollow structure body 2; an outer concrete layer 21, which is an outer hard material, provided on the outside of the inner concrete layer 22 at a distance in the thickness direction; and a foam layer 23, which is a buffer material with lower strength than the inner concrete layer 22 and the outer concrete layer 21, provided between the inner concrete layer 22 and the outer concrete layer 21. When an incoming projectile collides with the outer concrete layer 21 and explodes between the inner concrete layer 22 and the outer concrete layer 21, this explosive force is transmitted to both sides in the width direction on the outside of the protective structure 3 by damaging the weaker foam layer 23, and the explosive impact force is released to the end side of the foam layer 23, thereby protecting the hollow structure body 2 from explosion.

Description

Technical Field

[0001] The present invention relates to a hollow structure provided with a protective structure.

Background Art

[0002] Conventionally, as this type of hollow structure, there are known ammunition depots and powder magazines constructed of concrete in a tunnel for safety measures around (for example, Patent Document 1).

[0003] Also, in the construction method of a warehouse or the like in Patent Document 1, in a structure that requires rigidity such as a warehouse, a plurality of closed tubes are arranged, and both sides of these tube groups are covered with a water-impermeable sheet to form a flexible continuous structure on the outer shell of the warehouse or the like to be constructed. A construction method of a warehouse or the like has been proposed in which a curable fluid and air are partitioned by tubes so as not to be mixed and injected into the continuous structure in the contracted state, and the continuous structure is raised to a predetermined shape and constructed. It is described that this makes it highly safe because there is no scattering like a concrete structure in case of an accident.

[0004] However, if a shell hits a shallow part of the soil layer above the tunnel near the entrance of the tunnel, the shell may penetrate the inner wall of the tunnel and explode, and the structure may be damaged.

[0005] On the other hand, there is a bulletproof plate formed by laminating ceramic layers between steel plates (for example, Patent Document 2). When an armor-piercing bullet or the like hits this bulletproof plate, the ceramic layer between the steel plates spreads in a conical shape toward the rear in the plate thickness direction from the impact point and is damaged, and the impact force (impact stress) per unit area received by the rear steel plate becomes small, improving the bulletproof effect. However, if this bulletproof plate is used as it is for the protective structure of a hollow structure, an increase in material costs and construction costs is expected.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Special Publication No. 6-23518 [Patent Document 2] Japanese Patent Application Publication No. 4-222398 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] Therefore, the present invention aims to solve the above problems and provide a hollow structure equipped with a protective structure that can mitigate the explosive impact force of a projectile on the hollow structure at a relatively low cost. [Means for solving the problem]

[0008] The invention of claim 1 is a hollow structure that protects the hollow structure body from the explosion of a flying object by a protective structure provided on the outside of the hollow structure body, wherein the protective structure comprises an inner rigid material provided on the hollow structure body side, an outer rigid material provided on the outside at a distance from the inner rigid material in the thickness direction, and a cushioning material provided between the inner rigid material and the outer rigid material, having a lower strength than the inner rigid material and the outer rigid material.

[0009] The invention of claim 2 is characterized in that an opening is provided between the ends of the inner hard material and the outer hard material.

[0010] The invention of claim 3 is characterized in that the outer hard material consists of a concrete layer and the cushioning material consists of a foam layer.

[0011] The invention of claim 4 is characterized by comprising the protective structure and a covering structure that covers the hollow structure body.

[0012] The invention of claim 5 is characterized in that the covering structure is an embankment.

[0013] The invention of claim 6 is characterized in that the embankment is in contact with the opening. [Effects of the Invention]

[0014] According to the configuration of claim 1, when an incoming projectile collides with the outer hard material and explodes between the inner and outer hard materials, this explosive force is transmitted to both sides in the width direction of the protective structure by damaging the weaker buffer material. This explosive impact force is then released to the ends of the buffer material, preventing damage to the inner hard material. Furthermore, even if the inner hard material is damaged, the explosive force is released to the ends, weakening the explosive force applied to the hollow structure body and protecting the hollow structure body from explosion. In addition, the combination of the inner hard material, outer hard material, and buffer material allows for the provision of a protective structure at a relatively low cost.

[0015] According to the configuration of claim 2, the explosive force can be released from the opening to the outside of the protective structure.

[0016] According to the configuration of claim 3, since concrete has lower toughness than steel and the like, the outer concrete layer breaks while absorbing the impact force of the collision, the projectile explodes inside the foam layer, and the explosive force is released towards the edge of the foam layer, thereby protecting the hollow structure body.

[0017] According to the configuration of claim 4, the covering structure prevents the projectile from directly colliding with the protective structure, and the force applied to the protective structure and the hollow structure body during a projectile collision can be weakened by the projectile colliding with the covering structure.

[0018] According to the configuration of claim 5, the force applied to the protective structure by a projectile colliding with the embankment can be reduced, and in areas without a protective structure, the cover of the embankment can be increased to prevent damage to the hollow structure itself by the projectile.

[0019] According to the configuration of claim 6, when an explosive force reaches the end of the protective structure between the inner hard material and the outer hard material, the explosive force reaching the end can be absorbed by the embankment portion located at the opening. [Brief explanation of the drawing]

[0020] [Figure 1]It is a cross-sectional view of a hollow structure showing Example 1 of the present invention. [Figure 2] Same as above, it is a cross-sectional view of the hollow structure body. [Figure 3] Same as above, it is an enlarged cross-sectional view of the main part of the protective structure. [Figure 4] It is a cross-sectional view of a hollow structure showing Example 2 of the present invention. [Figure 5] It is a cross-sectional view of a hollow structure showing Example 3 of the present invention. [Figure 6] It is a cross-sectional view of a hollow structure showing Example 4 of the present invention. [Figure 7] It is a cross-sectional view of a hollow structure showing Example 5 of the present invention. [Figure 8] Same as above, it is a cross-sectional view in the longitudinal direction of the hollow structure. [Figure 9] It is a cross-sectional view in the longitudinal direction of a hollow structure showing Example 6 of the present invention. [Figure 10] It is a cross-sectional view of a hollow structure showing Example 7 of the present invention.

Mode for Carrying Out the Invention

[0021] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the embodiments described below do not limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential requirements of the present invention.

Examples

[0022] Hereinafter, examples of the present invention will be described with reference to the accompanying drawings. FIGS. 1 to 3 show Example 1 of the present invention. FIG. shows a cross-section of the hollow structure 1, and this hollow structure 1 includes a hollow structure body 2 made of concrete or the like and having a hollow interior, a protective structure 3 provided outside the hollow structure body 2, and an embankment 4 which is a covering structure covering the hollow structure body 2 and the protective structure 3. The hollow structure body 2 and the protective structure 3 are buried in the embankment 4.

[0023] The hollow structure body 2 comprises a pair of concrete side walls 11, 11, a concrete base plate 12 connecting the lower parts of these side walls 11, 11, and a precast concrete top plate 13 spanning between the upper parts of these side walls 11, 11. This top plate 13 is an arched roof section, and the cross-sectional shape shown in Figure 2 is continuous in the longitudinal direction. The hollow structure body 2 can be used as an evacuation shelter, ammunition depot, gunpowder magazine, or even an aircraft hangar.

[0024] During construction, the side wall sections 11, 11 and the base plate section 12 can be integrally formed by cast-in-place concrete, or they can be formed by combining precast concrete members. Furthermore, a recess 15 is formed on the installation surface 14 of the hollow structure body 2, which is one level lower than the installation surface 14, and the base plate section 12 is inserted into this recess 15. In addition, a connecting recess 16 (Figure 2) is formed at the upper end of the side wall section 11, with openings on the inner and upper sides, and the left and right ends of the top plate section 13 are connected by resting them on these left and right connecting recesses 16, 16.

[0025] On the upper outside of the hollow structure body 2, in this example, a horizontal protective structure 3 is provided, which has the same height in the left-right direction. The protective structure 3 in this example comprises an outer hard material outer concrete layer 21 and an inner concrete layer 22, which are spaced apart in the thickness direction, and a foamed material buffer layer 23 provided between these outer and inner concrete layers 21 and 22, with the outer concrete layer 21 on the upper side and the inner concrete layer 22 on the lower side.

[0026] As shown in Figure 1, in this example, the hollow structure body 2 and the protective structure 3 are embedded in the embankment 4 formed by piling up soil on the installation surface 14. The hollow structure body 2 has an entrance on one side in the longitudinal direction, while the other side in the longitudinal direction is closed off by a concrete slab or the like, and the concrete slab on the other side in the longitudinal direction is embedded in the embankment 4.

[0027] The outer and inner concrete layers 21 and 22 can be formed into flat plates by cast-in-place concrete, or they may be formed by arranging multiple plate-shaped precast concrete slabs 24 on the same plane.

[0028] Furthermore, the inner concrete layer 22, made of the same material, may be made thicker than the outer concrete layer 21, thereby effectively preventing the explosive force described later from being applied to the inside (bottom).

[0029] The foam layer 23 is formed by arranging multiple foam blocks 25 on the outside (outer surface) of the inner concrete layer 22 and stacking them in multiple layers. The foam blocks 25 are made of foamable synthetic resin blocks, and examples of foamable synthetic resins include expanded polystyrene, expanded polyethylene, expanded polypropylene, and expanded urethane. The foam layer 23 is thicker than the concrete layers 21 and 22.

[0030] Furthermore, cushioning materials other than foam can also be used, such as three-dimensional spring structures. An example of such a three-dimensional spring structure is Breathair (registered trademark: manufactured by Toyobo Co., Ltd.), whose raw material is a polyester-based thermoplastic elastomer. This three-dimensional spring structure is formed by melt-extruding a thermoplastic elastomer with rubber elasticity to create continuous wires, forming loops in the molten wires, and fusing adjacent wires in contact to create a three-dimensional structure consisting of random loops. Post-processing is performed to form stronger pseudo-crosslinking points, creating voids (not shown) between the wires that serve as ventilation parts, and forming a mesh-like mat form with rigid elasticity. However, similar to the foam, the three-dimensional spring structure is more susceptible to deformation and breakage when subjected to impact forces and has lower compressive strength compared to the inner and outer hard materials.

[0031] Then, similar to the case where the cushioning material is foam, blocks made of three-dimensional spring structures are formed, and a layer of three-dimensional spring structures that serves as cushioning material is formed by these multiple three-dimensional spring structure blocks, and an outer concrete layer 21 and an inner concrete layer 22 are provided on the outside and inside of the three-dimensional spring structure layer to constitute the protective structure 3. In this protective structure 3 equipped with a three-dimensional spring structure layer, the cushioning material, which has lower strength than the inner hard material and the outer hard material, is made of three-dimensional spring structures with ventilation parts, so that the explosive impact force can be efficiently released to the end side of the protective structure 3 by the ventilation parts.

[0032] Furthermore, the inner concrete layer 22 is located at a distance from the upper surface 13J of the top slab 13, and a gap 31 is provided between the lower surface 22K of the inner concrete layer 22 and the upper surface of the top slab 13. In this case, as shown in Figure 3, during the construction of the embankment 4, the upper surface of the embankment 4 under construction is formed at the height of the mounting surface 32, which is the lower surface of the inner concrete layer 22. After this, the inner concrete layer 22 is placed on the mounting surface 32, the foam layer 23 is placed on the inner concrete layer 22, and the outer concrete layer 21 is placed on the foam layer 23. Then, as shown in Figure 1, the embankment 4 is formed up to the height of its upper surface 4J.

[0033] Thus, the hollow structure 1 comprises a hollow structure body 2, a protective structure 3, and the embankment 4 which is a covering structure that covers the hollow structure body 2. Furthermore, a soil layer 33, which constitutes part of the embankment 4, is provided between the upper surface 13J of the top plate portion 13 of the hollow structure body 2 and the lower surface 22K of the protective structure 3.

[0034] Furthermore, an opening 26 without a hard material is provided between the end faces 21T and 22T of the outer and inner concrete layers 21 and 22, respectively. The end face 23T of the foam layer 23 is exposed to this opening 26 and is in contact with the embankment 4. In this example, nothing other than the embankment is provided between the end face 23T and the adjacent slope 34 of the embankment 4. The opening 26 is the opening portion between the corner 21D between the end face 21T and the inner surface of the outer concrete layer 21, and the corner 22D between the end face 22T and the outer surface of the inner concrete layer 22.

[0035] In this manner, openings 26 are provided at the ends of the inner concrete layer 22 and the outer concrete layer 21 to release the blast wave from an explosion within the protective structure 3 to the outside. For this reason, the end faces 22T of the inner concrete layer 22 and the end faces 21T of the outer concrete layer 21 are separated inward and outward, and the openings 26 with an opening width H (Figure 3) are provided between the concrete layers 21 and 22. In this example, the left and right end faces 23T, 23T of the foam layer 23 are not covered by a hard material and are in contact with the embankment 4.

[0036] For example, the width of the hollow structure body 2 is about 22m, and the height of the side wall 11 is about 5.8m. Since the span of the top plate 13 is relatively long, it is preferable to make the top plate 13 a gentle arch shape. In this case, if the top plate 13 is a semicircular arch shape, the distance between it and the flat protective structure 3 will differ greatly between the center in the left-right direction and both ends in the left-right direction. Therefore, it is preferable to make it a gentle arch shape with a greater curvature than a semicircle.

[0037] As an example, the width of the protective structure 3 relative to the hollow structure body 2 is either the same as or greater than the width of the hollow structure body 2. In this case, it is preferable that both end faces in the width direction of the protective structure 3 are located directly above the outer surface of the side wall portion 11 or further outward. The thickness of the concrete layers 21 and 22 is approximately 250 mm, and the thickness of the foam layer 23 is approximately 2000 mm. The thickness of the foam layer 23 is equal to the vertical opening width H of the opening 26. Furthermore, the spacing 31 is approximately 500 mm, and the spacing between the upper surface of the outer concrete layer 21 and the upper surface portion 4J of the embankment 4 is approximately 1500 mm. Note that the thicker the protective structure 3, the greater the buffering effect, but it is not desirable for it to be too thick as it will increase the dead load applied to the hollow structure body 2.

[0038] The upper layer 4A of the embankment 4 is the space between the upper surface of the outer concrete layer 21 and the upper surface portion 4J of the embankment 4, the left and right ends of the upper surface portion 4J are either directly above the outer surface of the side wall portion 11 or further out, and the left-right width of the upper surface portion 4J is greater than or equal to the left-right width of the protective structure 3. In addition, the angle θ of the slope 34 with respect to the horizontal is approximately 33.69 degrees, preferably between 28.69 degrees and 38.69 degrees.

[0039] In Figure 1, the distance between the outer surfaces of the left and right side walls 11,11 (the left-right width of the hollow structure body 2), the left-right width of the protective structure 3, and the left-right width of the top surface 4J are the same. In contrast, as shown in Embodiment 7 described later, the left-right width of the protective structure 3 and the left-right width of the top surface 4J can be made larger than the distance between the outer surfaces of the left and right side walls 11,11, and the left and right ends of the protective structure 3 and the left and right ends of the top surface 4J can be positioned outward in the left-right direction from the outer surface positions of the left and right side walls 11,11.

[0040] As an example, foam blocks 25 with a thickness of 500 mm, a width of 2000 mm or 1000 mm, and a length of approximately 2000 mm are used. Four layers of foam blocks 25 are stacked on top of each other, and the joints 25M of adjacent foam blocks 25 are positioned midway between the joints 25M, 25M of the upper and lower foam blocks 25, 25. Foam blocks 25 with a width of 1000 mm are provided on the end side of the protective structure 3.

[0041] Furthermore, the precast concrete slabs 24 used are approximately 2000 mm wide and 5000 mm long. In Figure 3, the foam blocks 25 on the right end of the second and fourth rows from the bottom are 1000 mm wide. Also, the left and right widths of the precast concrete slabs 24 in the inner concrete layer 22 are the same as the foam blocks 25 in the second and fourth rows from the bottom.

[0042] In a hollow structure 1 equipped with the protective structure 3 described above, if an explosive projectile (not shown), such as a missile or artillery shell, flies from the outside toward the upper surface 4J of the embankment 4, the projectile passes through the embankment 4 and hits the outer concrete layer 21, causing the projectile to explode and damage the outer concrete layer 21, the foam layer 23, which has a lower explosive strength than the outer and inner concrete layers 21 and 22, collapses as if blown away by the explosive force, diverting the explosive force toward the end faces 21T and 22T, absorbing the explosive force. Furthermore, if the explosive force has not attenuated, it blows away the embankment 4 adjacent to the end face 23T outwards, preventing the missile from penetrating the hollow structure body 2 inside the protective structure 3.

[0043] Furthermore, even if the inner concrete layer 22 is damaged, the soil layer 33 at intervals 31 prevents damage to the hollow structure body 2.

[0044] Thus, in this embodiment, corresponding to claim 1, in a hollow structure 1 in which the hollow structure body 2 is protected from the explosion of a flying object by a protective structure 3 provided on the outside of the hollow structure body 2, the protective structure 3 comprises an inner concrete layer 22 which is an inner hard material provided on the hollow structure body 2 side, an outer concrete layer 21 which is an outer hard material provided on the outside at a distance in the thickness direction from the inner concrete layer 22, and a buffer material which is provided between the inner concrete layer 22 and the outer concrete layer 21 and has a lower strength than the inner concrete layer 22 and the outer concrete layer 21 Because the structure includes a foam layer 23, when an incoming projectile collides with the outer concrete layer 21 and explodes between the inner concrete layer 22 and the outer concrete layer 21, this explosive force is transmitted to both sides in the width direction, which are the outside of the protective structure 3, by damaging the weaker foam layer 23. This releases the explosive impact force to the ends of the foam layer 23, preventing damage to the inner concrete layer 22. Furthermore, even if the inner concrete layer 22 is damaged, the release of the explosive force to the ends weakens the explosive force applied to the hollow structure body 2, thus protecting the hollow structure body 2 from explosion.

[0045] Furthermore, claim 1 also provides a protective structure 3 for structures at a relatively low cost by combining an inner concrete layer 22, an outer concrete layer 21, and a foam layer 23.

[0046] Thus, in this embodiment, corresponding to claim 2, an opening 26 is provided between the end faces 22T and 21T of the inner concrete layer 22 and the outer concrete layer 21, allowing the explosive force to escape to the outside of the protective structure 3 through the opening 26.

[0047] Thus, in this embodiment, corresponding to claim 3, the outer hard material consists of an outer concrete layer 21 and the cushioning material consists of a foam layer 23. Since concrete has lower toughness than steel, the outer concrete layer 21 is damaged while absorbing the impact force of the collision, the projectile explodes inside the foam layer 23, and the explosive force is released towards the end of the foam layer 23, thereby protecting the hollow structure body 2.

[0048] Thus, in this embodiment, corresponding to claim 4, the protective structure 3 and the hollow structure body 2 are covered by an embankment 4, so that the projectile does not directly collide with the protective structure 3 due to the embankment 4, and the force applied to the protective structure 3 and the hollow structure body 2 during a projectile collision is reduced by the projectile colliding with the embankment 4.

[0049] Thus, in this embodiment, corresponding to claim 5, since the covering structure is an embankment 4, the force applied to the protective structure 3 by a projectile colliding with the embankment 4 can be weakened, and in areas without the protective structure 3, the cover of the embankment 4 can be made thicker to prevent damage to the hollow structure body 2 by the projectile.

[0050] Thus, in this embodiment, corresponding to claim 6, since the embankment 4 is in contact with the opening 26, if the explosive force between the inner concrete layer 22 and the outer concrete layer 21 reaches the end of the protective structure 3, the explosive force that reaches the end can be absorbed by the portion of the embankment 4 located at the opening 26.

[0051] As described below, the effects of the embodiment are that multiple layers (4 layers) of foam blocks 25 are stacked, and multiple layers (3 layers) of overlapping surfaces 25N of the upper and lower foam blocks 25 are provided, and these lateral overlapping surfaces 25N act as passages that guide the blast, allowing the blast to be directed towards the end side of the protective structure 3.

[0052] Furthermore, since the angle θ of the slope 34 is between 28.69 degrees and 38.69 degrees, any flying object that flies towards the side wall portion 11 of the hollow structure body 2 will collide with the slope 34, and no explosive force will be directly applied to the side wall portion 11.

[0053] Furthermore, since the hollow structure body 2 is a warehouse for storing explosives such as ammunition magazines and gunpowder magazines, it can protect explosives from explosive projectiles and prevent the explosives stored inside the hollow structure body 2 from exploding.

[0054] Furthermore, when a protective structure 3 equipped with a three-dimensional spring structure layer as a cushioning material is adopted, the cushioning material, which has lower strength than the inner and outer hard materials, consists of a three-dimensional spring structure with ventilation sections. Therefore, the explosive impact force can be efficiently dissipated to the end side of the protective structure 3 by the ventilation sections. [Examples]

[0055] Figure 4 shows Embodiment 2 of the present invention, with the same reference numerals used for the same parts as in Embodiment 1, and their descriptions are omitted for brevity. In this embodiment, the protective structure 3 is formed in an arch shape following the top plate portion 13.

[0056] When forming concrete layers 21 and 22 using precast concrete slabs, for example, three identical precast concrete slabs are used to divide the arch shape into three sections. The three precast concrete slabs are assembled in the direction of the arch (the width direction of the hollow structure body 2), and multiple slabs are arranged in parallel along the length direction of the hollow structure body 2 to form concrete layers 21 and 22.

[0057] Furthermore, the foam block 42 is formed such that its lower surface is curved to correspond to the outer surface of the inner concrete layer 22, its upper surface is curved to correspond to the inner surface of the outer concrete layer 21, and the spacing between its left and right edges widens upwards. In the same manner as in Example 1, multiple layers of foam blocks 42 are provided.

[0058] Thus, in this embodiment, in accordance with the claims, the same functions and effects as in Embodiment 1 are achieved, and in this example, since the concrete layers 21 and 22 form an arch shape, the strength of the concrete layers 21 and 22 against loads from above can be ensured by the arch structure. [Examples]

[0059] Figure 5 shows Embodiment 3 of the present invention, with the same reference numerals used for the same parts as in the previous embodiments, and their descriptions are omitted for brevity. The protective structure 3 of this embodiment integrally comprises a lateral central portion 51 having the same height on both sides, and left and right inclined portions 53, 53 provided via the left and right ends of the central portion 51 and bent portions 52, 52, which become lower toward the left and right sides.

[0060] Furthermore, the outer and inner concrete layers 21 and 22 can be formed by cast-in-place concrete, or multiple precast concrete panels 24 may be arranged in the width and length directions of the hollow structure body 2.

[0061] Thus, in this embodiment, the same functions and effects as in the above embodiments are achieved in accordance with the claims, and in this example, since the concrete layers 21 and 22 consist of a combination of flat plate portions, the structure and construction are simplified. [Examples]

[0062] Figure 6 shows Embodiment 4 of the present invention, and the same reference numerals are used for the same parts as in the previous embodiments, and their descriptions are omitted for brevity. In this embodiment, a lower foam layer 23A is provided between the protective structure 3 and the top plate portion 13.

[0063] The lower foam layer 23A is formed by laying the foam blocks 25 on the upper surface 13J of the top slab 13, similar to the foam layer 23. In addition, at both ends in the width direction of the lower foam layer 23A, there are openings 26A without hard material between the end face 22T of the inner concrete layer 22 and the end of the top slab 13, and the embankment 4 is located at the end of the lower foam layer 23A.

[0064] Thus, in this embodiment, the same functions and effects as in the above embodiments are achieved in accordance with the claims. Furthermore, in this example, by using the lower foam layer 23A as the soil between the protective structure 3 and the top plate 13, the dead load applied to the hollow structure body 2 can be reduced. Moreover, when explosive force reaches the lower foam layer 23A, the lower foam layer 23A, which has a lower explosive strength than the inner concrete layer 21 and the top plate 13, collapses as if being blown away, releasing the explosive force towards the opening 26A and absorbing the explosive force. [Examples]

[0065] Figures 7 and 8 show Embodiment 5 of the present invention, and the same reference numerals are used for the same parts as in Embodiment 1, and their descriptions are omitted for brevity. In this embodiment, an arch-shaped cavity 62 is formed in the ground 61 by excavating in a mountainous area, and this cavity 62 is provided with at least one entrance / exit 63. The entrance and exit can also be provided separately. The cavity 62 comprises a flat bottom surface 64, side surfaces 65, 65 rising from both ends of the bottom surface 64, and an arch-shaped top surface 66 connecting these side surfaces 65, 65, and the side surfaces 65, 65 and the top surface 66 as a whole form a continuous arch shape.

[0066] Although an example of forming a cavity 62 in the natural ground 61 has been described, the cavity 62 may be a cavity formed in the natural ground 61, such as an abandoned mine, mining site, or existing tunnel.

[0067] The hollow structure body 2 is constructed within the cavity 62, and the protective structure 3 is provided in areas near the entrance 63 where the soil layer of the natural ground 61 is thin. As shown in Figure 8, at locations far from the entrance 63, the soil layer above the hollow structure 1 is thick, so the hollow structure body 2 is protected by the natural ground 61, and the protective structure 3 is not necessary.

[0068] In this case, as shown in Figure 7, after the construction of the hollow structure body 2, the cavity 62 is backfilled with backfill material 67 such as soil up to the height of the mounting surface 32, the protective structure 3 is then placed on the mounting surface 32, and after that, the remaining cavity 62 is backfilled with backfill material 67.

[0069] As an alternative, the backfill material 67 may be made of cement-based solidifying material such as cast-in-place concrete or mortar, in which case the concrete and the natural ground 61 form a covering structure.

[0070] Thus, the covering structure in this example consists of a cavity 62 within the ground 61 that covers the protective structure 3 and the hollow structure body 2, backfill material 67 that fills the cavity 62, and the ground 61.

[0071] Furthermore, above the entrance 63 of the hollow structure body 2, a retaining wall 68 is provided at the lower part of the slope 61S of the natural ground 61, supporting the soil and sediment on the slope 61S of the natural ground 61.

[0072] Thus, in this embodiment, the same effects and advantages as those in each of the above embodiments are achieved in accordance with claims 1 to 5, and if the backfill material 67 is replaced with soil, the same effects and advantages as those in claim 6 are achieved. [Examples]

[0073] Figure 9 shows Embodiment 6 of the present invention, and the same reference numerals are used for the same parts as in the previous embodiments, and their descriptions are omitted for brevity. In this embodiment, the size of the hollow structure body 2A on the inner side is made larger than the hollow structure body 2 on the entrance / exit 63 side.

[0074] If the aforementioned cavity 62 is formed with substantially the same cross-section in the longitudinal direction, the height of the hollow structure body 2 must be reduced by at least the height (thickness) of the protective structure 3 in order to provide a protective structure 3 on the entrance 63 side where the soil cover is small. In contrast, the height dimension of the hollow structure body 2A on the far side is formed to be higher than the hollow structure body 2 on the entrance 63 side. The hollow structure body 2A has the same configuration as the hollow structure body 2 except that the side wall portion 11 is higher than that of the hollow structure body 2.

[0075] Furthermore, the opening on the front of the hollow structure body 2A, which is formed by the difference in height between the hollow structure bodies 2 and 2A, is closed by the cover 69 to prevent soil and sand from entering through the opening.

[0076] Thus, in this embodiment, in accordance with the claims, the same functions and effects as in the above embodiments are achieved. Furthermore, in this example, by making the height dimension of the hollow structure body 2A on the rear side higher than the hollow structure body 2 on the entrance / exit 63 side, the internal space of the hollow structure body 2A can be made wider overall. [Examples]

[0077] Figure 10 shows Embodiment 7 of the present invention, with the same reference numerals used for the same parts as in the previous embodiments, and their descriptions are omitted for brevity. In this embodiment, the left-right width L3 of the protective structure 3 and the left-right width of the upper surface 4J of the embankment 4 are set wider than the left-right width L2 of the hollow structure body 2.

[0078] In Example 1, extensions 3E, 3E are provided at the left and right ends of the protective structure 3 by a left and right width L, L. The left and right width L3 of the protective structure 3 and the left and right width L4 of the upper surface 4J are made larger than the left and right width L2, which is the distance between the outer surfaces of the left and right side walls 11, 11. The left and right widths L3, L4 are equal, and the left and right ends of the protective structure 3 and the left and right ends of the upper surface 4J are located outward in the left and right directions by the amount of the extensions 3E, 3E compared to the left and right outer surface positions of the hollow structure body 2.

[0079] Thus, in this embodiment, in accordance with the claims, the same functions and effects as in the above embodiments are achieved. Furthermore, in this example, extensions 3E, 3E are provided by extending the left and right ends of the protective structure 3 by a left and right width L, L. Since the left and right width L3 of the protective structure 3 and the upper surface 4J of the embankment 4 are wider than the left and right width L2 of the hollow structure body 2, the top plate 13, which is the roof portion of the hollow structure body 2, can be protected over a wide area in the left and right direction. Moreover, in the hollow structure body 2, which has a concrete top plate 13 that is stretched between the upper parts of the side wall portions 11, 11 and has both left and right ends connected to the upper parts of the side wall portions 11, 11, the connection points between the left and right ends of the top plate 13 and the side wall portions 11, 11 can be protected by the extensions 3E, 3E.

[0080] As an alternative modification, the left-right width L4 may be made wider than the left-right width L3, and the left and right ends of the upper surface portion 4J may be positioned outward in the left-right direction from the left and right ends of the protective structure 3. This allows for a thicker cover of the hollow structure body 2 by the embankment 4, thereby improving the protective effect of the embankment 4.

[0081] Furthermore, the present invention is not limited to these embodiments, and various modifications can be implemented within the scope of the gist of the invention. For example, in the embodiments, concrete is exemplified as the rigid material, but steel plates or other materials may be used as long as they have higher strength than the cushioning material. Furthermore, as the covering structure, the area up to the height of the mounting surface 32 may be made of cast-in-place concrete or mortar, and the area above the mounting surface may be made of embankment, with the opening being made of embankment. Also, the inner and outer rigid materials may be made of different materials as long as they have higher strength than the cushioning material. For example, the inner rigid material may be made of steel plates and the outer rigid material may be made of concrete. Furthermore, it goes without saying that extensions may be provided to the protective structures of Embodiments 2 to 6. Also, bombs dropped from airplanes and the like are also flying objects. Furthermore, the top surface and slope of the embankment may be covered with plates of various materials. Also, a three-dimensional spring structure may be used in the protective structures of Embodiments 2 to 6. [Explanation of Symbols]

[0082] 1 Hollow structure 2,2A hollow structure body 3 Protective structure 4. Embankment (covering structure) 21. Outer concrete layer (outer hard material) 22. Inner concrete layer (inner hard body) 23. Foam layer (cushioning material) 26 Opening

Claims

1. In a hollow structure in which a protective structure provided on the outside of the hollow structure body protects the hollow structure body from the explosion of a flying object, The aforementioned protective structure is The inner rigid material provided on the main body side of the hollow structure, This inner hard material and the outer hard material provided on the outside at a distance in the thickness direction, A cushioning material with lower strength than the inner and outer hard materials is placed between these inner and outer hard materials. A hollow structure equipped with a protective structure characterized by having the following features.

2. A hollow structure having a protective structure according to claim 1, characterized in that an opening is provided between the ends of the inner hard material and the outer hard material.

3. A hollow structure having a protective structure according to claim 1 or 2, characterized in that the outer hard material consists of a concrete layer and the cushioning material consists of a foam layer.

4. A hollow structure equipped with the protective structure according to claim 2, characterized in that it comprises the protective structure and a covering structure that covers the main body of the hollow structure.

5. A hollow structure having a protective structure according to claim 4, characterized in that the covering structure is an embankment.

6. A hollow structure having a protective structure according to claim 5, characterized in that the embankment is in contact with the opening.

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