Drainage structure and method for constructing drainage structure

Abstract

To prevent or suppress alkaline water in an existing underground skeleton from flowing out into the ground from a backfill hole part penetrating an existing underground pressure-resistant panel.SOLUTION: The water drainage structure 100 includes a backfill foundation 110 constructed by backfilling an existing underground framework 10 surrounded by an existing underground external wall 12 and an existing underground pressure-resistant panel 14 and formed of a CO2 immobilizing glass 50 in which carbon dioxide is immobilized at least below a natural water level SS, a backfill hole portion 120 constructed by drilling the backfill foundation 110 and backfilling a pile hole 20 penetrating the existing underground pressure-resistant panel 14 and formed of the CO2 immobilizing glass 50 in which carbon dioxide is immobilized at least below the natural water level SS, and a pumping well 70 for pumping up underground framework water in the existing underground framework 10 flowing out to a foundation G from the backfill hole portion 120 penetrating the existing underground pressure-resistant panel 14 together with ground water by a pump 76 and draining the water on the ground.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a drainage structure and a method for constructing the drainage structure. [Background technology]

[0002] Patent Document 1 discloses a technology related to a building demolition method for demolishing an existing building. In this prior art, first, the above-ground portion of the building is demolished, and the underground structural portion is backfilled with the debris from the demolished above-ground portion. Next, the underground portion of the building is demolished while the backfilled debris is removed, leaving the existing columns and beams in the underground portion in a buttress shape. After leaving the columns and beams in the underground portion in a buttress shape, the demolition debris backfilled in the underground portion is compacted to form a construction ground.

[0003] Patent Document 2 discloses a technique for recovering cement paste from waste concrete. This prior art technique includes a first step of bringing a carbon dioxide-containing gas into contact with the waste concrete to fix carbon dioxide, a second step of applying an electric pulse to the waste concrete from the first step to pulverize it, and a third step of sieving the waste concrete after the second step and recovering the under-sieve concrete.

[0004] Patent Document 3 discloses a technique for backfilling buried piles. In this prior art, a backfilling material is injected into a buried hole created by pulling out a buried pile, and a neutral solidification material that exhibits a neutral range after solidification is used as the backfilling material.

[0005] Patent Document 4 discloses a technique relating to a cast-in-place pile having a concrete fill in which an insulating auxiliary tool that forms a cross-sectional defect is embedded, and a method for constructing a foundation having such a cast-in-place pile. In this prior art, the cast-in-place pile has a concrete pile body and main pile reinforcement driven into the pile body. A backfilled pile head is provided on the top surface of the pile body, in which the main pile reinforcement is embedded and extends upward from the pile body. The backfilled pile head is made of recycled gravel and recycled sand. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-189960 [Patent Document 2] Japanese Patent Publication No. 2022-126253 [Patent Document 3] Patent Publication No. 2021-161833 [Patent Document 4] Japanese Patent Application Publication No. 2018-165431 Summary of the Invention [Problem to be solved by the invention]

[0007] The existing underground structure, surrounded by the existing underground exterior walls and the existing underground pressure plate, is backfilled with concrete rubble or recycled crushed stone to create a backfilled ground. Holes are drilled in the constructed backfilled ground, and piles are inserted through the pile holes that penetrate the existing underground pressure plate, with their heads positioned lower than the existing underground pressure plate. The pile holes are then backfilled with concrete rubble or recycled crushed stone to create a backfilling hole. In addition, water from within the existing underground structure that has leaked into the ground from the backfilling hole that penetrates the existing underground pressure plate is pumped up together with groundwater using a pumping well and drained to the surface.

[0008] In this case, the water in the existing underground structure reacts with the concrete rubble or recycled crushed stone used for backfilling and becomes alkaline. Since alkaline water cannot be directly discharged into the sewer, the water pumped up by the pump must be temporarily stored in a notch tank or similar, and neutralized using a neutralization device or similar before being discharged.

[0009] In view of the above, an object of the present invention is to prevent or inhibit alkaline water in an existing underground structure from leaking into the ground through a backfill hole that penetrates an existing underground pressure-resistant plate. [Means for solving the problem]

[0010] The first aspect is a drainage structure comprising: a backfilled ground constructed by backfilling the inside of an existing underground structure surrounded by an existing underground outer wall and an existing underground pressure plate, and made of concrete rubble or recycled crushed stone that fixes carbon dioxide at least below the natural water level; a backfilled hole section constructed by drilling the backfilled ground and backfilling pile holes that penetrate the existing underground pressure plate, and made of concrete rubble or recycled crushed stone that fixes carbon dioxide at least below the natural water level; and a pumping well that pumps up water from inside the existing underground structure that has flowed out into the ground from the backfilled hole section that penetrates the existing underground pressure plate, together with groundwater, and drains it to the surface.

[0011] In the drainage structure described in the first aspect, the backfilled ground and the backfilling hole are made of concrete rubble or recycled crushed stone with carbon dioxide immobilized therein at least below the natural water level. This prevents or suppresses the water in the existing underground structure from becoming alkaline due to the concrete rubble or recycled crushed stone. This prevents or suppresses alkaline water from leaking into the ground from the backfilling hole that penetrates the existing underground pressure plate.

[0012] Furthermore, calcium is prevented or suppressed from being extracted from the concrete rubble or recycled crushed stone into the water within the existing underground structure, which in turn prevents or suppresses calcium from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0013] The second aspect is a drainage structure comprising: a backfilled ground constructed by backfilling an existing underground structure surrounded by an existing underground outer wall and an existing underground pressure plate with concrete rubble or recycled crushed stone; a backfill hole section constructed by drilling holes in the backfilled ground and backfilling pile holes that penetrate the existing underground pressure plate, the backfill hole section being made of a backfill material that is acidic at least below the natural water level; and a pumping well that pumps up water from within the existing underground structure that has flowed out into the ground from the backfill hole section that penetrates the existing underground pressure plate together with groundwater and drains it to the surface.

[0014] In the drainage structure described in the second aspect, the backfill hole is made of acidic backfill material at least below the natural water level. Therefore, water in the existing underground structure that has become alkaline due to concrete rubble or recycled crushed stone is neutralized as it passes through the backfill hole. This prevents or suppresses alkaline water from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0015] A third aspect is the drainage structure according to the second aspect, further comprising a supply device for supplying carbon dioxide gas to the backfilling hole portion.

[0016] In the drainage structure described in the third aspect, calcium extracted from the water in the existing underground structure reacts with concrete debris or recycled crushed stone and is converted into calcium carbonate by carbon dioxide gas supplied to the backfill hole, thereby preventing or suppressing calcium from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0017] The fourth aspect is a drainage structure comprising: backfilled ground constructed by backfilling an existing underground structure surrounded by an existing underground outer wall and an existing underground pressure-resistant plate with concrete rubble or recycled crushed stone; a backfill hole constructed by drilling holes in the backfilled ground and backfilling pile holes penetrating the existing underground pressure-resistant plate with concrete rubble or recycled crushed stone; a supply device that supplies carbon dioxide gas to the backfill hole; and a pumping well that pumps up water from within the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure-resistant plate together with groundwater and drains it to the surface.

[0018] In the drainage structure described in the fourth aspect, the concrete rubble or recycled crushed stone in the backfill hole is immobilized by the supplied carbon dioxide gas, turning it into weakly acidic concrete rubble or recycled crushed stone. Therefore, water in the existing underground structure that has become alkaline due to the concrete rubble or recycled crushed stone is neutralized as it passes through the backfill hole. This prevents or suppresses alkaline water from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0019] In addition, calcium extracted from concrete rubble or recycled crushed stone into the water in the existing underground structure is converted into calcium carbonate by carbon dioxide gas supplied to the backfill hole, thereby preventing or suppressing calcium from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0020] A fifth aspect is a construction method for a drainage structure, comprising the steps of: backfilling an existing underground structure surrounded by an existing underground outer wall and an existing underground pressure plate with concrete rubble or recycled crushed stone that has immobilized carbon dioxide at least to a level below the natural water level to construct a backfilled ground; drilling holes in the backfilled ground to construct pile holes that penetrate the existing underground pressure plate and install piles through the pile holes with their heads positioned lower than the existing underground pressure plate; backfilling the pile holes with concrete rubble or recycled crushed stone that has immobilized carbon dioxide at least to a level below the natural water level to construct a backfill hole portion; and providing a pumping well that pumps up water from within the existing underground structure that has leaked into the ground from the backfill hole portion that penetrates the existing underground pressure plate together with groundwater, and drains the water to the surface.

[0021] In the construction method for a drainage structure described in the fifth aspect, the backfilled ground and the backfilling hole are filled with concrete rubble or recycled crushed stone that has immobilized carbon dioxide at least below the natural water level. This prevents or suppresses the water in the existing underground structure from becoming alkaline due to the concrete rubble or recycled crushed stone. This prevents or suppresses alkaline water from leaking into the ground from the backfilling hole that penetrates the existing underground pressure plate.

[0022] Furthermore, the extraction of calcium that would otherwise be extracted when water in the existing underground structure reacts with concrete debris or recycled crushed stone is prevented or suppressed, thereby preventing or suppressing calcium from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0023] A sixth aspect is a construction method for a drainage structure, comprising the steps of: backfilling the inside of an existing underground structure surrounded by an existing underground outer wall and an existing underground pressure plate with concrete rubble or recycled crushed stone to construct a backfilled ground; drilling holes in the backfilled ground to construct pile holes that penetrate the existing underground pressure plate and install piles through the pile holes with their heads positioned lower than the existing underground pressure plate; backfilling the pile holes with acidic backfill material at least below the natural water level to construct a backfill hole section; and installing a pumping well that pumps up water from inside the existing underground structure that has flowed out into the ground from the backfill hole section that penetrates the existing underground pressure plate together with groundwater and drains it to the surface.

[0024] In the construction method for a drainage structure described in the sixth aspect, the backfill hole is filled with acidic backfill material at least below the natural water level. Therefore, water in the existing underground structure that has become alkaline due to concrete rubble or recycled crushed stone is neutralized as it passes through the backfill hole. This prevents or suppresses alkaline water from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0025] A seventh aspect is a construction method for a drainage structure, comprising the steps of: backfilling an existing underground structure surrounded by an existing underground outer wall and an existing underground pressure plate with concrete rubble or recycled crushed stone to construct a backfilled ground; drilling the backfilled ground to construct pile holes that penetrate the existing underground pressure plate and install piles through the pile holes with their heads positioned lower than the existing underground pressure plate; backfilling the pile holes with concrete rubble or recycled crushed stone to construct a backfilled hole section; supplying carbon dioxide gas to the backfilled hole section; and installing a pumping well that pumps up water from within the existing underground structure that has flowed out into the ground from the backfilled hole section that penetrates the existing underground pressure plate together with groundwater and drains it to the surface.

[0026] In the drainage structure construction method described in the seventh aspect, the concrete rubble or recycled crushed stone in the backfill hole is immobilized by the supplied carbon dioxide gas, turning it into weakly acidic concrete rubble or recycled crushed stone. Therefore, water in the existing underground structure that has become alkaline due to the concrete rubble or recycled crushed stone is neutralized as it passes through the backfill hole. Therefore, alkaline water is prevented or suppressed from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate.

[0027] In addition, calcium extracted from the existing underground structure by reacting with the concrete debris or recycled crushed stone in the water is converted into calcium carbonate by the carbon dioxide gas supplied to the backfill hole, thereby preventing or suppressing calcium from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate. [Effects of the Invention]

[0028] According to the present invention, alkaline water in an existing underground structure can be prevented or inhibited from leaking into the ground from a backfill hole that penetrates an existing underground pressure-resistant plate. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 2 is a cross-sectional view showing a schematic structure of the drainage structure of the first embodiment. [Figure 2] 3A to 3D are process diagrams showing a construction method for the drainage structure of the first embodiment. [Figure 3] This is a graph comparing the pH values ​​of a sample made by mixing CO2 immobilized litter with tap water, a sample made by mixing regular litter with tap water, and tap water. [Figure 4] This is a graph comparing the calcium content of a sample made by mixing CO2 immobilized litter with tap water, a sample made by mixing regular litter with tap water, and tap water. [Figure 5] This is a perspective view showing the efflorescence phenomenon caused by calcium adhering to the filter at the intake of the pump. [Figure 6] FIG. 10 is a cross-sectional view showing a schematic structure of a drainage structure of a second embodiment. [Figure 7] FIG. 10 shows the lower structure of the supply pipe. [Figure 8] FIG. 10 is a cross-sectional view showing a schematic structure of a drainage structure according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] First Embodiment A drainage structure and a construction method for the drainage structure according to a first embodiment of the present invention will be described.

[0031] It should be noted that each drawing is merely a schematic representation. The dimensions and proportions of each element shown in the drawings may not necessarily correspond to the actual ones. The dimensions, proportions, number, etc. of each element may also not necessarily correspond between multiple drawings. Hatching representing cross sections has been omitted if it makes the view difficult to see.

[0032] In addition, descriptions of configurations and techniques that are not directly related to the present invention and well-known configurations and techniques may be omitted or simplified.

[0033] [Drainage structure] First, the drainage structure will be described.

[0034] As shown in FIG. 1, the drainage structure 100 is configured to include backfilled ground 110, a backfilled hole portion 120, and a pumping well .

[0035] The existing underground structure 10 is composed of an existing underground exterior wall 12 and an existing underground pressure plate 14 that remain after the existing building is demolished. Water has accumulated inside this box-shaped existing underground structure 10 due to the inflow of rainwater and groundwater. Note that line SS indicates the natural water level inside the existing underground structure 10. For convenience, the water inside the existing underground structure 10 will be referred to as "water inside the underground structure."

[0036] The backfilled ground 110 is constructed by backfilling the existing underground structure 10 with concrete rubble. At least the part of the backfilled ground 110 below the natural water level SS of the underground structure is constructed by backfilling with concrete rubble that has fixed carbon dioxide.

[0037] The concrete gravel that has immobilized carbon dioxide is referred to as CO2 immobilization gravel 50, while the general concrete gravel that does not immobilize carbon dioxide is referred to as normal gravel 60. In this embodiment, the CO2 immobilization gravel 50 is backfilled up to a level slightly above the natural water level SS, and the level above that is backfilled with normal gravel 60. The CO2 immobilization gravel 50 in this embodiment is weakly acidic with a pH of 6.8.

[0038] The backfill hole portion 120 is constructed by drilling the backfill ground 110 and backfilling the pile holes 20 (see also FIG. 2(D)) that penetrate the existing underground pressure-resistant plate 14 with concrete gravel. The pile holes 20 will be described later. In this embodiment, the backfill hole portion 120 is backfilled with CO2 fixation gravel 50 up to a level slightly above the natural water level SS of the underground structure, and the area above that is backfilled with normal gravel 60.

[0039] Note that any method may be used to produce the CO2 fixation gravel 50, i.e., to fix carbon dioxide in concrete gravel, but in this embodiment, the CO2 fixation gravel 50 was produced using a wet carbonation treatment device. Furthermore, the backfill ground 110 and the backfill hole 120 may contain backfill material other than the CO2 fixation gravel 50 and the normal gravel 60, such as surplus soil. This also applies to other embodiments described below.

[0040] The pumping well 70 is constructed by drilling the backfill ground 110 and penetrating the existing underground pressure plate 14. The pumping well 70 of this embodiment is composed of a steel strainer pipe.

[0041] The portion of the pumping well 70 (strainer pipe) that comes into contact with the backfill ground 110 does not have a slit, so that water inside the underground structure 10 does not flow into the pumping well 70. Furthermore, a water-stopping material 72 is provided on the inner wall of the portion of the pumping well 70 that penetrates the existing underground pressure plate 14, so that water inside the underground structure does not flow into the pumping well 70 from this portion. In this embodiment, fixed bentonite is used as the water-stopping material 72, but the material is not limited to this.

[0042] A pump 76 attached to the tip of a drainage tube 74 is inserted into the pumping well 70. The pump 76 pumps up the water within the existing underground structure 10 that has flowed out into the ground from a backfill hole 120 that penetrates the existing underground pressure plate 14, together with groundwater, and drains it above ground. A filter 79 made of wire mesh, as shown in Figure 5, is provided around the intake of the pump 76. The calcium CA attached to the filter 79 in Figure 5 will be described later.

[0043] In this embodiment, the water pumped up by the pump 76 is temporarily stored in a notch tank 80 installed on the backfill ground 110, etc., and then discharged from the notch tank 80 into a sewer, river, etc., but this is not limited to this, and the water may be discharged into a sewer, river, etc. without being temporarily stored in the notch tank 80.

[0044] [Drainage structure construction method] Next, a construction method for the drainage structure will be described.

[0045] As shown in Figure 2(A), after the existing building is demolished, the existing underground structure 10 is backfilled with CO2 fixation gravel 50 up to a level slightly above the natural water level SS, and then backfilled with normal gravel 60 to construct backfilled ground 110. At this point, groundwater has not yet flowed into the existing underground structure 10, so the water inside the underground structure may not have accumulated up to the natural water level SS, but even in that case, backfilling is performed assuming the natural water level SS.

[0046] As shown in Figures 2(B) to 2(D), the backfill ground 110 is drilled to make pile holes 20 (see also Figure 2(D)) that penetrate the existing underground pressure-resistant plate 14. The pile holes 20 are then filled with bentonite 21 (see Figure 2(B)) and then piles 30 are erected. As shown in Figure 2(D), the pile heads 32 of the piles 30 are located below the existing underground pressure-resistant plate 14. Note that drilling the pile holes 20 that penetrate the existing underground pressure-resistant plate 14 allows groundwater to flow into the existing underground structure 10.

[0047] As shown in FIG. 1, after erecting the pile 30, the pile hole 20 (see FIG. 2(D)) is backfilled with CO2 fixation gravel 50 up to a level slightly above the natural water level SS of the underground structure, and then backfilled with normal gravel 60 to form the backfill hole 120.

[0048] In addition, the backfill ground 110 is drilled to open a well hole (not shown) that penetrates the existing underground pressure-resistant plate 14, and a steel strainer pipe is inserted to construct a pumping well 70. A water-stop material 72 is provided on the inner wall of the part of the pumping well 70 that penetrates the existing underground pressure-resistant plate 14 to stop water leakage.

[0049] Then, a pump 76 is inserted into the pumping well 70, and the water within the underground structure 10 that has flowed out into the ground from the backfill hole 120 that penetrates the existing underground pressure plate 14 is pumped up together with groundwater and drained to the surface.

[0050] [Effect] Next, the operation of this embodiment will be described. Note that the arrows in Fig. 1 schematically show the flow of water in the underground structure and groundwater.

[0051] The groundwater level is lowered by pumping groundwater from the pumping well 70 with a pump 76 and discharging it.

[0052] When groundwater is pumped up and drained using the pump 76 of the pumping well 70, the water inside the underground structure 10 enters the backfill hole 120 and flows out into the ground G. The water inside the underground structure that has flowed out into the ground G is pumped up together with the groundwater by the pump 76 and drained above ground.

[0053] Here, a drainage structure of a comparative example in which the existing underground structure 10 and the pile holes 20 are all backfilled with normal gravel 60 will be described.

[0054] Since calcium hydroxide (Ca(OH)2) contained in the normal granules 60 is strongly alkaline, the water inside the underground structure also becomes alkaline. The alkaline water inside the underground structure that is pumped up by the pump 76 together with the groundwater cannot be discharged into the sewer or river. Therefore, the water temporarily stored in the notch tank 80 must be neutralized using a neutralization device or the like before being discharged.

[0055] In addition, calcium is extracted from the water in the underground structure by reacting with the normal gravel 60. If the pump 76 continues to suck up water containing calcium, the pump 76 may become clogged due to efflorescence caused by calcium, which may lead to breakdown (see Figure 5). In addition, calcium hydroxide (Ca(OH)2) dissolved from the normal gravel 60 reacts with water (H2O) to produce calcium (Ca 2+ ) is considered to be the case.

[0056] However, in this embodiment, the backfilled ground 110 and the backfilling hole 120 below the natural water level SS are made up of CO2 fixation gravel 50 that fixes carbon dioxide. When fixating carbon dioxide (CO2), calcium hydroxide (Ca(OH)2) reacts with carbon dioxide (CO2) to form calcium carbonate (CaCO3). Therefore, the water in the underground structure is prevented or suppressed from becoming alkaline.

[0057] In this way, the underground structure body water in the existing underground structure 10 is prevented or inhibited from becoming alkaline, and the alkaline underground structure body water is prevented or inhibited from flowing out into the ground G from the backfill hole portion 120 that penetrates the existing underground pressure-resistant plate 14. Therefore, after the underground structure body water that has flowed out into the ground G is pumped up by the pump 76 together with groundwater, it can be discharged into the sewer or river without undergoing neutralization treatment.

[0058] Furthermore, even if calcium hydroxide (Ca(OH)2) remains in the CO2 fixation grit 50, it is only a small amount. Furthermore, since the CO2 fixation grit 50 is weakly acidic with a pH of 6.8, even if the water inside the underground structure becomes alkaline, it is neutralized by the CO2 fixation grit 50. Therefore, the alkalinity is low and the water can be discharged into sewers or rivers without undergoing neutralization treatment.

[0059] Even if the alkalinity is at a level that prevents the water from being discharged into sewers or rivers, the alkalinity is lower than in the drainage structure of the comparative example, so the neutralization treatment capacity can be lower.

[0060] In addition, in the CO2 fixation glass 50, calcium hydroxide (Ca(OH)2) reacts with carbon dioxide (CO2) to form calcium carbonate (CaCO3), as described above. Therefore, the dissolved calcium hydroxide (Ca(OH)2) reacts with water (H2O) to form calcium (Ca 2+ ), and extraction is prevented or suppressed. Therefore, calcium is prevented or suppressed from flowing into the ground from the backfill hole 120 that penetrates the existing underground pressure plate 14, and efflorescence of the pump 76 due to calcium is prevented or suppressed.

[0061] (experiment) Next, we will explain an experiment that confirmed that water mixed with CO2 fixation ash 50 can be prevented or inhibited from becoming alkaline, and that calcium can be prevented or inhibited from being extracted into water mixed with CO2 fixation ash 50.

[0062] First, the samples used in the experiment will be described.

[0063] Samples A to C were made by mixing tap water with CO2 fixation ash 50, which was made by fixing CO2 in concrete ash collected from a demolition site. The CO2 fixation ash 50 was made by blowing CO2 gas into the concrete ash for five consecutive days to fix it.

[0064] Samples D to F were prepared by mixing tap water with normal gravel 60 made from concrete gravel collected from the same demolition site as samples A to C. The normal gravel 60 was prepared by oven-drying the concrete gravel until it was completely dry.

[0065] In addition to Samples A to F, tap water was also tested.

[0066] pH value Figure 3 shows the results of measuring the pH values ​​of samples A to F and tap water. From Figure 3, samples A to C, which used CO2 immobilizing glass 50, had pH values ​​lower than the allowable value K1, while samples D to F, which used regular glass 60, had pH values ​​higher than the allowable value K1. In other words, it can be seen that CO2 immobilizing glass 50 can prevent or suppress alkalinity. In this experiment, the allowable value K1 was set to pH 8.6 because the Water Supply Act stipulates that the pH of drinking water should be between 5.8 and 8.6, but the allowable value is not limited to this.

[0067] Calcium content Figure 4 shows the results of measuring the calcium content of samples A to F and tap water. As can be seen from Figure 4, the calcium content of samples A to C, which use CO2-immobilizing glass 50, and samples D to F, which use regular glass 60, exceeds the allowable value K2, but samples A to C have a lower calcium content than samples D to F. In other words, it can be seen that CO2-immobilizing glass 50 can suppress calcium extraction. Note that in this experiment, the allowable value K2 was set at 300 mg / L, which is the upper limit of the calcium content in drinking water under the Water Supply Act, but it is not limited to this value.

[0068] Second Embodiment Next, a drainage structure according to a second embodiment of the present invention will be described. Note that the same members as those in the first embodiment are designated by the same reference numerals, and redundant descriptions will be omitted or simplified.

[0069] [Drainage structure] First, the drainage structure will be described.

[0070] As shown in FIG. 6, the drainage structure 200 of this embodiment is configured to include a backfilled ground 210, a backfilled hole portion 120, a pumping well 70, and a supply device 270.

[0071] The backfill hole 120 and the pumping well 70 are the same as those in the first embodiment, and therefore a description thereof will be omitted. The backfill ground 210 is constructed by backfilling the entire existing underground structure 10 with ordinary gravel 60.

[0072] The supply device 270 is a device that supplies carbon dioxide gas to the portion of the backfilling hole 120 that is below the natural water level SS. The supply device 270 is configured to include a device main body 272 that is installed on the backfilling ground 210, etc., and a supply pipe 274 connected to the device main body 272. The device main body 272 has a tank filled with carbon dioxide gas and a pump (not shown). The supply pipe 274 is inserted so that its tip is below the natural water level SS of the backfilling hole 120, and in this embodiment, is located at the vertical midpoint of the portion of the backfilling hole 120 that is backfilled with CO2 fixation gravel 50.

[0073] 7, a large number of supply holes 276 are formed on the circumferential surface of the lower part of the supply pipe 274. Carbon dioxide gas from a tank of the device main body 272 (see FIG. 6) is sent to the supply pipe 274 by a pump, blown out from the lower supply holes 276, and supplied to the part of the backfilling hole 120 that is backfilled with CO2 fixation glass 50.

[0074] [Drainage structure construction method] Next, a construction method for the drainage structure will be described.

[0075] As shown in Figure 6, after the existing building is demolished, the existing underground structure 10 is backfilled with ordinary gravel 60 to construct a backfilled ground 210. The backfilled ground 210 is drilled to open pile holes 20 (see also Figure 2(D)) that penetrate the existing underground pressure-resistant plate 14, and the pile holes 20 are temporarily filled with bentonite 21 (see Figure 2(B)) before the piles 30 are erected.

[0076] After erecting the pile 30, the pile hole 20 (see FIG. 2(D)) is backfilled with CO2 fixation gravel 50 up to a level slightly above the natural water level SS of the underground structure, and then backfilled with normal gravel 60 to form the backfill hole 120. When backfilling the pile hole 20, a supply pipe 274 is buried.

[0077] In addition, the backfill ground 210 is excavated to open a well hole (not shown) that penetrates the existing underground pressure plate 14, and a steel strainer pipe is inserted into the well hole to construct a pumping well 70.

[0078] Carbon dioxide gas is sent from the device body 272 to the supply pipe 274, and is supplied from the supply hole 276 at the bottom (see FIG. 7) to the area of ​​the backfilling hole 120 that is backfilled with the CO 2 fixation glass 50.

[0079] In addition, a pump 76 is inserted into the pumping well 70, and the water within the existing underground structure 10 that has flowed out into the ground from the backfill hole 120 that penetrates the existing underground pressure plate 14 is pumped up together with groundwater and drained to the surface.

[0080] [Effect] Next, the operation of this embodiment will be described. Note that the arrows in Fig. 6 schematically show the flow of water in the underground structure and groundwater.

[0081] When groundwater is pumped up to the pumping well 70 by the pump 76 and then discharged, the water inside the underground structure 10 enters the backfill hole 120 and flows out into the ground G. The water inside the underground structure that has flowed out into the ground G is pumped up together with the groundwater by the pump 76 and discharged above ground.

[0082] The backfilled ground 210 is constructed by backfilling the entire existing underground structure 10 with ordinary gravel 60. Therefore, the water in the underground structure is alkaline and calcium is extracted from it.

[0083] However, at least the area below the natural water level SS in the backfill hole 120 where the pile hole 20 is backfilled is made of weakly acidic CO2 fixation gravel 50 with a pH of 6.8. Therefore, the water inside the underground structure, which has become alkaline, is neutralized as it passes through the backfill hole 120.

[0084] Furthermore, since the carbon dioxide gas supplied to the backfilling hole 120 is weakly acidic, the water inside the underground structure that has become alkaline due to the carbon dioxide gas is neutralized.

[0085] This prevents or inhibits alkaline underground structure water from flowing out into the ground G from the backfill hole 120 that penetrates the existing underground pressure-resistant plate 14. Therefore, after the underground structure water that has flowed out into the ground G is pumped up by the pump 76 together with groundwater, it can be discharged into the sewer or river without undergoing neutralization treatment.

[0086] In addition, the calcium extracted into the water inside the underground structure is converted into calcium (Ca 2+ ) becomes calcium carbonate (CaCO3). Also, if there is carbon dioxide (CO2) that is not completely fixed in the CO2 fixation glass 50, that amount will be converted into calcium (Ca 2+ ) becomes calcium carbonate (CaCO3). Therefore, calcium is prevented or suppressed from leaking into the ground from the backfill hole 120 that penetrates the existing underground pressure plate 14, and efflorescence of the pump 76 due to calcium is prevented or suppressed.

[0087] Here, the neutralization performance of the CO2 fixation glass 50 will be explained.

[0088] Assuming that the water in the underground structure is 500L at pH 10.0 and the CO2 fixation glass 50 is 500L at pH 6.8, ((10.0pH×500L)+(6.8pH×500L)) / (500L+500L))=8.4pH and becomes nearly neutral.

[0089] In addition, the range of water that can be discharged into the sewer is as follows: 5.0≦pH<9.0 Therefore, if the pH is less than 9.0, The water inside the underground structure has a pH of 10.0. pH10.0 x 500L x 2.2 = 1100L This becomes: Therefore, if the water inside the underground structure is less than 1,100 L, it can be discharged into the sewer.

[0090] In this embodiment, the water inside the underground structure is neutralized by the acidic (weakly acidic in this embodiment) CO2 fixation gravel 50 that constitutes the backfill hole portion 120 that backfills the pile hole 20. If the alkalinity of the water inside the underground structure is high and the amount is large, it is possible that the neutralization ability of the CO2 fixation gravel 50 will be lost midway or the water will flow out before it is neutralized.

[0091] However, as mentioned above, assuming that the CO2 fixation granules are 500L at pH 6.8, it is thought that the neutralization ability can be maintained up to 1100L of water in the underground structure at pH 10.0.

[0092] Third Embodiment Next, a drainage structure and a construction method for the drainage structure according to a third embodiment of the present invention will be described. Note that the same members as those in the first and second embodiments are designated by the same reference numerals, and redundant descriptions will be omitted or simplified.

[0093] [Drainage structure] First, the drainage structure will be described.

[0094] As shown in FIG. 8, the drainage structure 300 of this embodiment is configured to include a backfilled ground 310, a backfilled hole 320, a pumping well 70, and a supply device 270.

[0095] The backfilled ground 310 is constructed by backfilling the entire existing underground structure 10 with ordinary gravel 60. The backfilled hole portion 320 is also constructed by backfilling all of the pile holes 20 (see also FIG. 2(D)) with ordinary gravel 60.

[0096] [Drainage structure construction method] As shown in Figure 8, after the existing building is demolished, the existing underground structure 10 is backfilled with ordinary gravel 60 to construct a backfilled ground 210. The backfilled ground 210 is drilled to open pile holes 20 (see also Figure 2(D)) that penetrate the existing underground pressure-resistant plate 14, and the pile holes 20 are temporarily filled with bentonite 21 (see Figure 2(B)) before the piles 30 are erected. After the piles 30 are erected, the pile holes 20 (see Figure 2(D)) are backfilled with ordinary gravel 60 to construct a backfilled hole section 320. When the pile holes 20 are backfilled, a supply pipe 274 is buried.

[0097] In addition, the backfill ground 310 is excavated to open a well hole (not shown) that penetrates the existing underground pressure plate 14, and a steel strainer pipe is inserted into the well hole to construct a pumping well 70.

[0098] Carbon dioxide gas is then sent from the device body 272 to the supply pipe 274, and the carbon dioxide is supplied to the backfill hole 320 from the supply hole 276 at the bottom (see FIG. 7).

[0099] In addition, a pump 76 is inserted into the pumping well 70, and the water within the underground structure 10 that has flowed out into the ground from the backfill hole 320 that penetrates the existing underground pressure plate 14 is pumped up together with groundwater and drained to the surface.

[0100] [Effect] Next, the operation of this embodiment will be described. Note that the arrows in Fig. 7 schematically show the flow of water in the underground structure and groundwater.

[0101] The supplied carbon dioxide gas immobilizes carbon dioxide in the normal gravel 60 of the backfill hole 320, turning it into weakly acidic CO2 immobilizing gravel 50. Therefore, the water inside the underground structure 10, which has been made alkaline by the normal gravel 60, is neutralized as it passes through the backfill hole 320. This prevents or inhibits alkaline water from leaking into the ground G from the backfill hole 320 that penetrates the existing underground pressure-resistant plate 14.

[0102] Furthermore, since the carbon dioxide gas supplied to the backfill hole 320 is weakly acidic, the water inside the underground structure, which has also become alkaline due to the carbon dioxide gas, is neutralized.

[0103] Therefore, after the water inside the underground structure that has flowed out into the ground G is pumped up together with groundwater by the pump 76, it can be discharged into the sewer or river without undergoing neutralization treatment.

[0104] As described above, by supplying carbon dioxide to the backfilling hole 320, the carbon dioxide is immobilized in the normal grit 60, which becomes the weakly acidic CO2 immobilizing grit 50. Therefore, it is desirable to drain the water from the pumping well 70 until the normal grit 60 becomes the weakly acidic CO2 immobilizing grit 50 after the carbon dioxide is supplied to the backfilling hole 320, for example, several days after the carbon dioxide is supplied to the backfilling hole 320.

[0105] In addition, the calcium extracted into the water inside the underground structure is converted into calcium (Ca 2+ ) is calcium carbonate (CaCO 3 ) Therefore, calcium is prevented or suppressed from leaking into the ground from the backfill hole 320 that penetrates the existing underground pressure plate 14, and efflorescence of the pump 76 due to calcium is prevented or suppressed.

[0106] <Other> The present invention is not limited to the above embodiment.

[0107] For example, in the second embodiment, carbon dioxide gas is supplied to the backfilling hole 120 through the supply pipe 274, but this is not limitative and carbon dioxide gas may not be supplied. In this case, however, the effect of preventing or suppressing efflorescence caused by calcium in the pump 76 cannot be obtained.

[0108] In addition, for example, in the second embodiment, the stake hole 20 is backfilled with the weakly acidic CO2 fixation gravel 50 as an example of an acidic backfilling material, but the present invention is not limited to this. Note that the weakly acidic CO2 fixation gravel 50 may further be mixed with an acidic material.

[0109] Furthermore, for example, in the above embodiment, the normal gravel 60 is concrete gravel, and the CO2 immobilization gravel 50 is concrete gravel with carbon dioxide immobilized therein, but this is not limited to this. Recycled crushed stone may be used instead of the concrete gravel (normal gravel 60), and recycled crushed stone with carbon dioxide immobilized therein may be used instead of the concrete with carbon dioxide immobilized therein (CO2 immobilization gravel 50). Furthermore, these may be mixed.

[0110] Furthermore, for example, in the above embodiment, the pumping well 70 is drilled through the backfill ground 110, 210, 310 and penetrates the existing underground pressure plate 14, but this is not limited to this. The pumping well 70 may be installed within the site where it is necessary to lower the groundwater level, and may be constructed by drilling the ground G next to the existing underground structure 10, for example.

[0111] Furthermore, the present invention can be embodied in various forms without departing from the spirit and scope of the present invention. A plurality of embodiments and modifications can be implemented in combination as appropriate. [Explanation of symbols]

[0112] 10 Existing underground structure 12 Existing basement exterior wall 14 Existing underground pressure-resistant plate 20 stake hole 30 stakes 32 Pile head 50 CO2 fixation glass (carbon dioxide fixation concrete glass) 60 Regular gravel (concrete gravel) 70 Pumping Well 76 Pump 100 Drainage structure 110 Backfill ground 120 Backfill hole section 200 Drainage structure 210 Burial Site 270 Supply Unit 300 Drainage Structure 320 Burial site SS natural water level

Claims

1. A backfill ground constructed by backfilling the existing underground structure surrounded by the existing underground outer wall and the existing underground pressure-resistant plate, and consisting of concrete rubble or recycled crushed stone that fixes carbon dioxide at least below the natural water level; A backfill hole portion constructed by drilling the backfill ground and backfilling a pile hole penetrating the existing underground pressure plate, and made of concrete rubble or recycled crushed stone that fixes carbon dioxide at least below the natural water level; a pumping well that pumps up water from the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure plate together with groundwater and drains it to the ground; Drainage structure with

2. A backfilled ground constructed by backfilling the existing underground structure surrounded by the existing underground exterior wall and the existing underground pressure plate with concrete rubble or recycled crushed stone; A backfill hole portion constructed by drilling the backfill ground and backfilling a pile hole penetrating the existing underground pressure plate, the backfill hole portion being made of an acidic backfill material at least below the natural water level; a pumping well that pumps up water from the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure plate together with groundwater and drains it to the ground; Drainage structure with

3. A supply device is provided to supply carbon dioxide gas to the backfill hole. The drainage structure according to claim 2.

4. A backfilled ground constructed by backfilling the existing underground structure surrounded by the existing underground exterior wall and the existing underground pressure plate with concrete rubble or recycled crushed stone; A backfill hole portion constructed by drilling the backfill ground and backfilling a pile hole penetrating the existing underground pressure plate with concrete gravel or recycled crushed stone; a supply device for supplying carbon dioxide gas to the backfill hole; a pumping well that pumps up water from the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure plate together with groundwater and drains it to the ground; Drainage structure with

5. a step of constructing a backfilled ground by backfilling the existing underground structure surrounded by the existing underground outer wall and the existing underground pressure plate with concrete rubble or recycled crushed stone that has fixed carbon dioxide at least below the natural water level; A process of drilling the backfill ground to construct pile holes that penetrate the existing underground pressure plate, and installing piles through the pile holes so that the pile heads are positioned lower than the existing underground pressure plate; A step of backfilling the pile hole at least to a natural water level or below with carbon dioxide-immobilized concrete rubble or recycled crushed stone to construct a backfill hole portion; a step of providing a pumping well that pumps up the water in the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure plate together with groundwater and drains it above ground; A construction method for a drainage structure equipped with the above.

6. a step of constructing a backfilled ground by backfilling the existing underground skeleton surrounded by the existing underground outer wall and the existing underground pressure plate with concrete rubble or recycled crushed stone; A process of drilling the backfill ground to construct pile holes that penetrate the existing underground pressure plate, and installing piles through the pile holes so that the pile heads are positioned lower than the existing underground pressure plate; A step of backfilling the front pile hole with an acidic backfill material at least to a level below the natural water level to construct a backfill hole portion; a step of providing a pumping well that pumps up the water in the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure plate together with groundwater and drains it above ground; A construction method for a drainage structure equipped with the above.

7. a step of constructing a backfilled ground by backfilling the existing underground skeleton surrounded by the existing underground outer wall and the existing underground pressure plate with concrete rubble or recycled crushed stone; A process of drilling the backfill ground to construct pile holes that penetrate the existing underground pressure plate, and installing piles through the pile holes so that the pile heads are positioned lower than the existing underground pressure plate; A step of backfilling the front pile hole with concrete gravel or recycled crushed stone to construct a backfill hole portion; supplying carbon dioxide gas to the backfill hole; a step of providing a pumping well that pumps up the water in the existing underground structure that has flowed out into the ground from the backfill hole that penetrates the existing underground pressure plate together with groundwater and drains it above ground; A construction method for a drainage structure equipped with the above.

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