Reinforcement method of existing underground structure

Abstract

To provide a reinforcement method of an existing underground structure reinforcing an existing underground shelter and the existing underground structure through a chemical injection method to enable them to be used effectively as an underground shelter.SOLUTION: A reinforcement method of an existing underground structure 11 is to improve durability against energy acting from the outside and / or shield performance against radiation through reinforcing the ground 1 of an outer periphery of the existing underground structure 11 through a chemical injection method to form a buffer body 12 by a reinforced foundation in the outer periphery of the existing underground structure 11. Further, durability, strength, and safety are further improved as an underground shelter against, for example, an incoming ballistic missile by forming the buffer body 12 by a reinforced foundation by injecting chemical in the outer periphery of the underground shelter where the existing underground structure 11 is the existing shelter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for reinforcing an existing underground structure by using a chemical injection method to reinforce an existing underground shelter against, for example, an incoming ballistic missile, and to a method for reinforcing an existing underground structure to effectively utilize it as an underground shelter. [Background technology]

[0002] During Russia's invasion of Ukraine, many Ukrainian citizens took refuge in basements and subways. Subways, in particular, are built deep enough to withstand a nuclear attack. In Japan, the Civil Protection Act of 2004 mandated local governments to designate evacuation shelters. However, as of 2023, only about 12,000 of the approximately 50,000 designated evacuation facilities were underground.

[0003] By positioning a wide range of existing underground facilities as shelters, it seems possible to effectively utilize them as underground shelters to run to in the event of a ballistic missile attack. However, since some of the country's subways are built at a relatively shallow depth, reinforcement is necessary to withstand the explosive energy of a missile, but effective methods for this have not yet been considered.

[0004] Patent Document 1 discloses a radiation shielding material characterized by using asphalt in the form of powder, pellets, blocks, and / or molded panels or plates as a material for shielding radiation.

[0005] Patent Document 2 discloses a radiation shielding device that uses tungsten, a tungsten compound, a tungsten-based alloy, or a mixture with other heavy metals (hereinafter referred to as "tungsten, etc.") as a material with a high radiation shielding rate, and that mixes a film-forming material 6 with shielding particles 1 made of the "tungsten, etc." to form a mixed shielding material 7, which is integrated with a cloth body 8 made of natural fibers such as cotton, linen, or silk, and / or synthetic fibers, and / or nonwoven fabric, and / or paper, etc., by a coating means such as coating, pasting, baking, or printing, to form a shielding cloth 9, and that connects the shielding cloth 9 to another piece of shielding cloth 9 by a connecting means 11 such as adhesion, welding, sewing, buttoning, or hook-and-loop fastener, to form radiation shielding members 12 of various shapes.

[0006] Patent Document 3 discloses a container having an interior structure made of a material that prevents radiation leakage.

[0007] Patent Documents 4 and 5 are filed by the present applicant, and Patent Document 4 discloses a durable silica grout and a durable silica ground improvement method using the durable silica grout.The durable ground injection grout and durable ground injection method use a non-alkaline silica grout whose active ingredient is silica sol, silica colloid, or water glass.

[0008] Patent Document 5 discloses a ground grouting material used in a ground grouting method in which fine particles are injected into the ground to increase its density and solidify it at the same time, the material being characterized by having blast furnace slag as the main ingredient, to which gypsum or magnesium oxide, or both, are added as active ingredients as reactants, and the pH of the ground grouting material is adjusted to 8 to 12. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-206055 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-044737 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-127439 [Patent Document 4] Patent No. 6460432 [Patent Document 5] Patent No. 7193105 [Non-patent literature]

[0010] [Non-Patent Document 1] Akio Yamaji, Shigeo Numata, Tetsuo Saito, "Design Method of Compensatory Shielding Incorporated into Concrete Walls for γ-Ray Shielding with Direct Ducts and Measurement and Analysis of Dose Rate Distribution," Journal of the Atomic Energy Society of Japan, Vol. 29, No. 6, pp. 77-85, 1987. [Non-patent document 2] Takashi Sekine, "Radiation Shielding," July 1970, RADIOISOTOPES, Vol. 19, No. 7, pp. 48-58 [Non-patent document 3] Takamitsu Sasaki, Ryozo Yonekura, Shunsuke Shimada, "Field verification test of the long-term hardening of consolidated ground using activated silica and ultrafine silica composites," 2019, 54th Geotechnical Engineering Research Conference, 0241, pp. 481-482 [Non-patent document 4] Daisuke Muto, "On the magnitude of earthquakes caused by explosions or collisions," Seismic Research Bulletin, Vol. 81, pp. 1-6, 2017 [Non-Patent Document 5] Katsumi Tanaka, "Analysis of Explosion Phenomena," Safety Engineering, Vol. 36, No. 6, pp. 383-389, 1997 Summary of the Invention [Problem to be solved by the invention]

[0011] In recent years, subways, underground shopping malls, tunnels, etc. have been considered as shelters from the perspective of national defense, but they were not built with such an event in mind, and some of them have since deteriorated over time, resulting in a decrease in strength and water leakage from joints, so it is necessary to strengthen underground concrete structures.

[0012] In particular, many subway tunnels are constructed using the shield tunneling method, and their segments use ordinary cement concrete with a thickness of approximately 75 mm to 225 mm. On the other hand, if they are expected to function as shelters against nuclear weapons, the concrete used is considered to be high-density heavy concrete containing barite and magnetite, with a thickness of approximately 150 mm to 400 mm. Therefore, existing subway tunnels cannot be expected to function as nuclear shelters (Non-Patent Documents 1 and 2).

[0013] Ground improvement methods are used in earthquake-resistant reinforcement work against earthquake motion. The principles of these methods include compaction, solidification, and shear deformation control. Compaction methods are prone to horizontal and vertical stress and displacement, making them difficult to apply to existing structures. Furthermore, while methods that prevent shear displacement can sometimes be carried out near existing structures, they are often difficult to apply in urban areas with many underground structures, and especially in the ground surrounding subway shields.

[0014] On the other hand, among the methods that rely on solidification, mechanical mixing methods are difficult to carry out when there are buried objects underground, and high-pressure jet mixing methods have the potential to affect buried objects underground as well as pose problems with sludge disposal. [Means for solving the problem]

[0015] The method for reinforcing existing underground structures of the present invention is characterized by reinforcing the ground around the periphery of the existing underground structure using a chemical injection method, and forming a buffer body made of reinforced ground around the periphery of the existing underground structure, thereby increasing durability against external energy and / or shielding against radiation.

[0016] The present invention aims to improve the ground around an existing underground structure by using a chemical grouting method, which is one of the solidification methods, and the conditions suitable for this purpose are set as follows. 1) The injection material used must be permanent grout. 2) Demonstrate sufficient earthquake resistance against vibrations caused by explosion energy. 3) Excellent permeability during construction and water-stopping properties as an improvement effect 4) If functionality against nuclear bombs is expected, the injection material must have radiation shielding properties. 5) Low-carbon injection materials and injection methods are desirable.

[0017] The applicant has already developed permanent grouts that are expected to have long-term durability, as described in Patent Documents 4 and 5, and has demonstrated the sustainability of their improvement effects (Non-Patent Document 3). For example, the solution-type grout described in Patent Document 4 has high permeability.

[0018] Furthermore, the suspension-type grout described in Patent Document 5 has a solidification mechanism similar to that of cement, so when injected into the ground around the periphery of an existing underground structure, the buffer formed by the reinforced ground around the periphery of the existing underground structure is expected to be strong and provide radiation shielding. Furthermore, because the main agent of the suspension-type grout is slag, it can be said to be a low-carbon grout because of its low carbon dioxide emission intensity.

[0019] The method of reinforcing existing underground structures according to the present invention forms a buffer of reinforced ground around the periphery of an existing underground structure, thereby increasing durability against external energy or shielding against radiation, and enabling the existing underground structure to be effectively utilized as an underground shelter.

[0020] In the method for reinforcing an existing underground structure according to the present invention, the existing underground structure may be an existing underground shelter. By reinforcing the existing underground shelter by injecting chemicals in the method for reinforcing an existing underground structure according to the present invention, it is possible to further improve the durability, strength, and safety of the underground shelter against, for example, incoming ballistic missiles.

[0021] In the method for reinforcing an existing underground structure according to the present invention, the range and strength of the buffer body may be designed to be strong and within a range that can withstand the explosive energy of an anticipated ballistic missile, etc. The buffer body, made of reinforced ground formed around the periphery of the existing underground structure by chemical injection, can perform seismic reinforcement of an existing underground shelter to protect it from vibrations caused by the explosive energy of an incoming ballistic missile.

[0022] Furthermore, in the method for reinforcing existing underground structures according to the present invention, it is advisable to calculate the range and strength of the buffer by converting the explosive energy of a ballistic missile or the like into seismic energy. The thickness of the ground improvement layer is preferably determined by converting the explosive energy of a warhead into seismic energy and verifying the safety of the target structure (Non-Patent Document 4). The thickness of the improvement layer can be determined by converting the explosive energy into earthquake energy (magnitude).

[0023] In addition, in the reinforcement method for existing underground structures according to the present invention, it is preferable to calculate the range and strength of the buffer by converting the explosive energy of a ballistic missile or the like into blast pressure. It is preferable to determine the thickness of the ground improvement layer by converting the explosive energy of a warhead into blast pressure and verifying the safety of the target structure (Non-Patent Document 5).

[0024] Furthermore, in the method for reinforcing an existing underground structure according to the present invention, it is preferable to use a chemical solution containing clay as the main material to which a radiation-shielding material has been added as the chemical solution for forming the buffer body. For even higher radiation shielding performance, it is effective to add a material containing clay as the main material to which a radiation-shielding material has been added to the high-strength grout described in Patent Document 5. Ground improvement using the chemical injection method allows the construction of a radiation-shielding wall around the existing structure.

[0025] Radiation permeability depends on the type of radiation and the type and thickness of the shielding material. Therefore, the thickness of the improved layer of shielding grout applied to the periphery of the concrete is determined taking these factors into consideration.

[0026] The thickness of the improved buffer layer may also be determined by calculating the blast pressure from the equivalent amount of explosive of trinitrotoluene (TNT). [Effects of the Invention]

[0027] The present invention allows existing underground structures to be effectively utilized as underground shelters. In particular, by using a suspension-type grouting material, it is possible to construct a radiation shielding wall in the ground, thereby improving safety. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic diagram showing one embodiment of a method for reinforcing an existing underground structure of the present invention. [Figure 2] 1 is a schematic diagram showing an embodiment of the method for reinforcing an existing underground structure of the present invention in the case where there is a buried pipe near the existing underground structure. [Figure 3] This is a graph showing the relationship between period and acceleration and seismic intensity (theoretical value) (when vibrations of a uniform period continue for several seconds). [Figure 4] This shows the TNT blast pressure measured in field experiments sponsored by the Ministry of International Trade and Industry and the Materials and Chemical Research Institute, as well as the US experimental values ​​and analytical results. It also compares the peak TNT overpressure from the cumulative experiment with the converted distance and analytical values. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to tables and drawings, but the present invention is not limited to the embodiments described below.

[0030] Figure 1 is a schematic diagram showing one embodiment of the present invention's method for reinforcing an existing underground structure 11. An existing underground structure 11 with a rectangular cross section is located in the ground 1, and an access passage 14 is provided on the side of the existing underground structure 11 to connect the existing underground structure 11 to the ground.

[0031] An injection pipe 13 is inserted from the ground 1 toward the top of the existing underground structure 1, and a chemical solution is injected into the top of the existing underground structure 11 to form a buffer body 12. Injection pipes 13 are also inserted into the side of the existing underground structure 11 and the side of the access passage 14, and a chemical solution is injected to form the buffer body 12. By surrounding the existing underground structure 11 with the ground-reinforced buffer body 12, it is possible to increase durability against external energy and shielding against radiation.

[0032] 2 is a schematic diagram showing a case where a buried pipe 2, such as a water supply / sewerage pipe or a gas pipe, is located near an existing underground structure 21, which has a circular cross section. The existing underground structure 21, which has a circular cross section, is located in the ground 1, and an access passage 24 is provided on the side of the existing underground structure 21, connecting the existing underground structure 21 to the ground.

[0033] An injection pipe 23 is inserted from inside the existing underground structure 21 toward the surrounding ground 2, and a chemical solution is injected along the outer diameter of the existing underground structure 21 to form a ground-reinforced buffer body 22. In addition, an injection pipe 23 is inserted into the side of the access passage 24 to form the buffer body 22.

[0034] As shown in Figures 1 and 2, the buffer bodies 12, 22 formed on the outer periphery of the existing underground structures 11, 21 can provide durability and a shielding effect against energy and radiation acting from the outside on the existing underground structures 11, 21. In addition, they can be effectively used as underground shelters against incoming ballistic missiles, for example.

[0035] Furthermore, the existing underground structures 11, 21 in the present invention may be structures that are installed underground, such as tunnels, subway stations, underground shopping malls, underground passageways, etc. Furthermore, by forming buffer bodies 12, 22 on the outer periphery of structures that were originally installed as underground shelters, the durability and strength of the underground shelters can be improved.

[0036] The injection material used for chemical injection in the reinforcement method for existing underground structures 11 and 21 of the present invention may be, for example, a solution-type injection material or a suspension-type injection material that the applicant has already developed as a permanent grout that can be expected to have long-term durability and has proven to have a sustainable ground improvement effect.

[0037] Solution-type grouting materials have high permeability. Suspension-type grouting materials have a solidification mechanism similar to that of cement, so the buffer bodies 12, 22 formed around the periphery of existing underground structures 11, 21 are expected to be strong and have radiation shielding effects. Furthermore, because the main agent of suspension-type grouting materials is slag, they have a low carbon dioxide emission intensity and can be said to be a low-carbon grouting material.

[0038] Furthermore, a chemical solution containing clay as the main material and added radiation shielding material may be used as the chemical solution for forming the buffer bodies 12, 22. For even higher radiation shielding performance, it is effective to add a material containing clay as the main material and added radiation shielding material to high-strength grout, and by reinforcing the ground using the chemical injection method, it is possible to construct a radiation shielding wall around the existing underground structures 11, 21.

[0039] In the reinforcement method for existing underground structures 11, 21 according to the present invention, the range and strength of the buffers 12, 22 are designed to be strong and have a range that can withstand the explosive energy of an anticipated ballistic missile. Earthquake-resistant reinforcement is performed by the buffers 12, 22 made of reinforced ground formed around the periphery of the existing underground structures 11, 21 by chemical grouting, and they can protect against vibrations caused by the explosive energy of an incoming ballistic missile.

[0040] The explosive energy of a ballistic missile may also be converted into seismic energy to calculate the range and strength of the buffers 12, 22. The thickness of the improved layer of the buffers 12, 22 formed by ground improvement is preferably determined by converting the explosive energy of the warhead into seismic energy and verifying the safety of the target structure. The thickness of the buffers 12, 22 can also be determined by converting the explosive energy into earthquake energy (magnitude).

[0041] Furthermore, in the reinforcement method for existing underground structures 11, 21 according to the present invention, the explosive energy of a ballistic missile may be converted into blast pressure to calculate the range and strength of the buffers 12, 22. Safety can be further enhanced by determining the thickness of the improved layer of the buffers 12, 22 formed by ground reinforcement by converting the explosive energy of the warhead into blast pressure and verifying the safety of the target structural parts of the existing underground structures 11, 21.

[0042] Since radiation permeability depends on the type of radiation and the type and thickness of the shielding material, it is advisable to determine the improved layer thickness of the buffer bodies 12, 22 formed on the concrete periphery of the existing structures 11, 21 taking these factors into consideration.

[0043] The improved layer thickness of the buffer bodies 12, 22 may also be determined by calculating the blast pressure from the equivalent amount of explosive of trinitrotoluene (TNT).

[0044] Example 1 An example of calculation is shown below. The explosion energy is calculated based on the amount of explosives in the assumed projectile. The calculation method is to calculate the amount of energy per 1g of explosives as 4.2 x 10 3 Let J. An example of the calculation results is shown in Table 1.

[0045] [Table 1]

[0046] The calculated explosion energy shown in Table 1 is converted to seismic energy using the semi-theoretical, semi-empirical formula of Gutenberg and Richter shown in Equation 1.

[0047]

number

[0048] Here, E is the explosion energy and M is the seismic energy. If we convert the explosion energy to seismic energy, we get Table 2.

[0049] [Table 2]

[0050] Figure 3 is a graph showing the relationship between period and acceleration and seismic intensity (theoretical values) (when vibrations of a uniform period continue for several seconds). The maximum depth measured in a shallow earthquake shows a value close to the seismic energy (M), so this value can be used to calculate the acceleration occurring in the ground from Figure 3. Note that the frequency in an explosion is 2 Hz to 60 Hz, so here we use a frequency of 20 Hz to calculate the acceleration from the seismic energy in Table 2, and then use Equation 2 to calculate the shear stress in the ground at a depth of 10 m, which results in Table 3.

[0051]

number

[0052] For the shear force calculated in Table 3, the improvement strength and improvement layer thickness are determined according to the design guidelines for each structure.

[0053] [Table 3]

[0054] Example 2 Next, as another calculation example, we will make a calculation assuming that the blast pressure caused by the impact and explosion will cause the ground to collapse. The blast pressure can be calculated from the relationship between the amount of explosives and the converted distance calculated from the distance in Figure 4. The converted distance is calculated using Equation 3.

[0055]

number

[0056] [Table 4]

[0057] Assuming that the blast pressure obtained in Table 4 will cause the ground to collapse, the improvement strength and thickness of the improvement layer are determined according to the design guidelines for each structure. [Explanation of symbols]

[0058] 1...Ground 2... Buried pipes (water and sewer pipes, gas pipes, etc.) 11...Existing underground structures 12...Buffer 13...Injection tube 14...Access passage 21...Existing underground structure 22...Buffer 23…Injection tube 24...Access passage

Claims

1. A method for reinforcing an existing underground structure, characterized by reinforcing the ground around the periphery of the existing underground structure using a chemical injection method, and forming a buffer body made of reinforced ground around the periphery of the existing underground structure, thereby increasing durability against external energy and / or shielding against radiation.

2. 2. The method for reinforcing an existing underground structure according to claim 1, wherein the existing underground structure is an existing underground shelter.

3. A method for reinforcing an existing underground structure as described in claim 1 or 2, characterized in that the range and strength of the buffer body are designed to be strong and have a range that can withstand the explosive energy of an anticipated ballistic missile.

4. 4. A method for reinforcing an existing underground structure according to claim 3, wherein the explosion energy is converted into seismic energy to calculate the range and strength of the buffer body.

5. 4. A method for reinforcing an existing underground structure according to claim 3, wherein the explosion energy is converted into blast pressure to calculate the range and strength of the buffer body.

6. 3. A method for reinforcing an existing underground structure according to claim 1 or 2, characterized in that the chemical solution used to form the buffer body is a chemical solution containing clay as the main material and to which a radiation shielding material has been added.

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