Drainage structure and method for constructing drainage structure

Abstract

To prevent or suppress alkaline water from flowing out into the ground from a back-filling hole penetrating an existing underground pressure-resistant panel.SOLUTION: The water drainage structure 100 includes a backfill foundation 110 constructed by backfilling at least a portion below a natural water level SS in an existing underground framework 10 surrounded by an existing underground external wall 12 and an existing underground pressure-resistant panel 14 with CO2 immobilizing glass and backfilling normal glass 60 thereon, a backfill hole portion 120 constructed by drilling a hole in the backfill foundation 110 and backfilling a pile hole 20 penetrating the existing underground pressure-resistant panel 14 and made of a backfill material 122 impermeable at least below the natural water level SS, a pumping well 70 for pumping up ground water and discharging it to the ground, and a water drainage device 150 for pumping up water in the existing underground framework 10.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 using a pumping well is pumped up together with groundwater using a pumping pump 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 lifting 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 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 backfilled hole section being made of backfill material that is impermeable at least below the natural water level; a pumping well that pumps up groundwater and drains it above ground; and a drainage device that pumps up water from within the existing underground structure and drains it.

[0011] In the drainage structure described in the first aspect, the backfill hole is made of impermeable backfill material at least below the natural water level. This prevents or suppresses water inside the existing underground structure that has become alkaline due to concrete rubble or recycled crushed stone from leaking into the ground through the backfill hole that penetrates the existing underground pressure plate. Therefore, since the drainage device only neutralizes the alkaline water inside the existing underground structure, the amount of water to be neutralized is small, resulting in low cost.

[0012] A second aspect is the drainage structure according to the first aspect, in which at least the natural water or less in the existing underground structure is backfilled with concrete rubble or recycled lime that has fixed carbon dioxide.

[0013] In the drainage structure described in the second aspect, the backfill ground below the natural water level is made of concrete rubble or recycled lime with carbon dioxide immobilized. This prevents or suppresses the water in the existing underground structure from becoming alkaline. Therefore, there is no need to neutralize the alkaline water in the existing underground structure that is drained by the drainage system, or even if neutralization is required, it is low cost.

[0014] The third 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 demolished 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 installing piles through the pile holes with their heads positioned lower than the existing underground pressure plate; backfilling the pile holes with impermeable backfill material to construct a backfill hole portion; pumping groundwater using a pumping well and draining it above ground; and pumping water from inside the existing underground structure and draining it using a drainage device.

[0015] In the drainage structure described in the third aspect, the backfill hole is made of impermeable backfill material at least below the natural water level. This prevents or suppresses water from leaking into the ground from the backfill hole that penetrates the existing underground pressure plate, even if the water inside the existing underground structure has become alkaline due to the concrete rubble or recycled crushed stone. Therefore, since the drainage device only neutralizes the alkaline water inside the existing underground structure, the amount of water to be neutralized is small, resulting in low cost.

[0016] A fourth aspect is the drainage structure according to the third aspect, in which at least the natural water or less in the existing underground structure is backfilled with concrete rubble or recycled lime that has fixed carbon dioxide.

[0017] In the drainage structure described in the fourth aspect, the backfill ground is made of an acidic backfill material at least below the natural water level. This prevents or suppresses the water in the existing underground structure from becoming alkaline. Therefore, there is no need to neutralize the alkaline water in the existing underground structure that is drained by the drainage system, or even if neutralization is required, it is low cost. [Effects of the Invention]

[0018] 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]

[0019] [Figure 1]1 is a cross-sectional view showing a schematic structure of a drainage structure according to an embodiment. [Figure 2] 1A to 1D are process diagrams showing a construction method of a drainage structure according to one 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 a water pump. DETAILED DESCRIPTION OF THE INVENTION

[0020] <Embodiment> A drainage structure and a construction method for the drainage structure according to one embodiment of the present invention will be described.

[0021] 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.

[0022] 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.

[0023] [Drainage structure] First, the drainage structure will be described.

[0024] As shown in FIG. 1, the drainage structure 100 is configured to include a backfilled ground 110, a backfilled hole portion 120, a pumping well 70, and a drainage device 150.

[0025] 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."

[0026] 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.

[0027] 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 normal gravel 60 is backfilled above that.

[0028] The backfill hole portion 120 is constructed by drilling the backfill ground 110 and backfilling a pile hole 20 (see also Figure 2 (D)) that penetrates the existing underground pressure-resistant plate 14. The pile hole 20 will be described later. In this embodiment, the backfill hole portion 120 is backfilled with an impermeable material 122 up to a level slightly above the natural water level SS of the water in the underground structure, and the area above that is backfilled with regular gravel 60. The impermeable material 122 may be any material that does not allow water to enter the pile hole 20, and examples of such material that can be used include water-blocking clay, soil cement, and water glass.

[0029] Furthermore, any method may be used to produce the CO2 fixation gravel 50, that is, the method of fixating carbon dioxide in concrete gravel, but in this embodiment, the CO2 fixation gravel 50 was produced using a wet carbonation treatment device. The backfilled ground 110 and the backfilling hole 120 may contain backfill material other than the CO2 fixation gravel 50 and the normal gravel 60, such as surplus soil. However, if the impermeable material 122 contains surplus soil or the like, the amount must be such that impermeability is ensured.

[0030] 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.

[0031] 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.

[0032] A pumping pump 76 attached to the tip of the pumping tube 74 is inserted into the pumping well 70. The pumping pump 76 pumps up groundwater and discharges it above ground. A filter 79 made of wire mesh, as shown in Figure 5, is provided around the intake of the pumping pump 76. The calcium CA adhering to the filter 79 in Figure 5 will be described later.

[0033] The drainage device 150 is configured to have a drainage pump 152 and a drainage tube 154. The drainage pump 152 is attached to the tip of the drainage tube 154. In the drawing, the drainage pump 152 is buried at the bottom end of the backfilled ground 110, but it is not buried in the backfilled ground 110, and is lowered appropriately as the backfilled ground 110 is excavated.

[0034] In addition, in this embodiment, the water pumped up by the water lifting pump 76 and the water drainage pump 152 is temporarily stored in a notch tank 80 installed on the backfill ground 110, etc., and then drained from the notch tank 80 into a sewer, river, etc., but this is not limited to this, and the water may be drained into a sewer, river, etc. without being temporarily stored in the notch tank 80.

[0035] [Drainage structure construction method] Next, a construction method for the drainage structure will be described.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] A pumping pump 76 is inserted into the pumping well 70 to pump up groundwater and drain it above ground. Also, a drainage pump 152 of a drainage device 150 pumps up water from within the underground structure and drains it above ground.

[0041] In addition, water that wells up within the underground structure as the underground construction work such as excavation of the backfill ground 110 progresses is pumped up and drained by the drainage device 150 as appropriate.

[0042] [Effect] Next, the operation of this embodiment will be described.

[0043] The groundwater level is lowered by draining the groundwater from the pumping well 70 using a pumping pump 76.

[0044] At least the backfill hole 120 below the natural water level SS is made up of impermeable material 122, so that the water inside the underground structure 10 does not infiltrate the backfill hole 120 and flow out of the ground G. Therefore, when groundwater is pumped up from the pumping well 70 by the pumping pump 76 and drained, the water inside the underground structure does not rise along with the groundwater.

[0045] In addition, water inside the existing underground structure 10 is pumped up and drained by the drainage device 150 as appropriate in accordance with the progress of the underground construction work.

[0046] 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.

[0047] In the backfill hole portion where all of the pile holes 20 are backfilled with normal gravel 60, the water inside the underground structure penetrates into the backfill hole portion 120 and flows out into the ground. When groundwater is pumped up and drained from the pumping well 70 by the pumping pump 76, the water inside the underground structure is also raised together with the groundwater.

[0048] 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 together with the groundwater by the pumping pump 76 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.

[0049] In addition, calcium is extracted from the water in the underground structure by reacting with the normal gravel 60. If the water pump 76 continues to suck up water containing calcium, the pump 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.

[0050] However, in this embodiment, the backfilled ground 110 below the natural water level SS is made up of CO2 fixation gravel 50 that fixes carbon dioxide. The CO2 fixation gravel 50 fixes carbon dioxide (CO2) by reacting calcium hydroxide (Ca(OH)2) with carbon dioxide (CO2) to produce calcium carbonate (CaCO2). 3 ) This prevents or suppresses the water inside the underground structure from becoming alkaline.

[0051] Furthermore, as mentioned above, the backfill hole portion 120 is made of impermeable material 122 at least below the natural water level SS, so when groundwater is pumped up and drained from the pumping well 70 by the pumping pump 76, the water inside the underground structure is not raised along with the groundwater.

[0052] 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, the underground structure water that has flowed out into the ground G will not be pumped up by the pumping pump 76 together with groundwater.

[0053] Furthermore, the water inside the underground structure pumped up by the drainage device 150 is not alkaline, and therefore can be discharged into the sewer or river without undergoing neutralization treatment.

[0054] 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 will be neutralized by the CO2 fixation grit 50.

[0055] 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.

[0056] Furthermore, as mentioned above, the backfill hole 120 is made of impermeable material 122 at least below the natural water level SS, so water inside the underground structure will not enter the backfill hole 120 and flow out into the ground G.

[0057] 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, efflorescence caused by calcium in the drainage pump 152 is prevented or suppressed.

[0058] (experiment) Next, we will explain an experiment that confirmed that water mixed with CO2 fixation ash 50 can be prevented or suppressed from becoming alkaline, and that calcium extraction into water mixed with CO2 fixation ash 50 can be prevented or suppressed.

[0059] First, the samples used in the experiment will be described.

[0060] Samples A to C were prepared by mixing tap water with CO2 fixation glass 50, which was made by fixing CO2 in concrete rubble collected from a demolition site. The CO2 fixation glass 50 was made by blowing CO2 gas into the concrete rubble for five consecutive days to fix it.

[0061] 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.

[0062] In addition to Samples A to F, tap water was also tested.

[0063] 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 suppress alkalinity. In this experiment, the allowable value K1 was set to a value between 5.8 and 8.6, since 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.

[0064] 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.

[0065] <Other> The present invention is not limited to the above embodiment.

[0066] For example, in the above embodiment, the water in the underground structure is neutralized by forming the CO2 fixation gravel 50 below the natural water level SS in the backfill ground 110, but this is not limited to this. The water in the underground structure may be neutralized by other methods.

[0067] Alternatively, for example, the entire existing underground structure 10 may be backfilled with ordinary gravel 60. In this case, the water inside the underground structure becomes alkaline, so the water pumped up by the drainage device 150 must be neutralized before being discharged into a sewer, river, etc. However, compared to when the water inside the underground structure is pumped up together with groundwater and neutralized, the amount of water to be neutralized is small and the cost is low. In this case, the water inside the underground structure is temporarily stored in a tank separate from the notch tank 80 and neutralized.

[0068] 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.

[0069] Furthermore, for example, in the above embodiment, the pumping well 70 is drilled through the backfill ground 110 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.

[0070] In addition, for example, in the above embodiment, the drainage pump 152 of the drainage device 150 appropriately drains water from within the underground structure that wells up due to excavation work on the backfill ground 110, but this is not limited to this. For example, a drainage pipe may be driven into the backfill ground 110, and the water may be drained by suction using a vacuum pump or the like installed above ground.

[0071] Furthermore, the present invention can be embodied in various forms without departing from the spirit and scope of the present invention. The embodiments and modifications can be combined as appropriate. [Explanation of symbols]

[0072] 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 Water pump 100 Drainage structure 110 Backfill ground 120 Backfill hole section 122 Impermeable materials 150 Drainage system SS natural water level

Claims

1. 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, and made of a backfill material that is impermeable at least below the natural water level; Pumping wells that pump groundwater and drain it above ground, A drainage device that pumps up and drains water from the existing underground structure; Drainage structure with

2. At least the natural water level in the existing underground structure is backfilled with carbon dioxide-immobilized concrete or recycled lime. The drainage structure according to claim 1 .

3. a step of constructing a backfilled ground by backfilling the existing underground structure surrounded by the existing underground exterior wall and the existing underground pressure plate with demolished concrete debris 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 impermeable backfill material to construct a backfill hole portion; The process of pumping groundwater through pumping wells and discharging it above ground. A process of pumping and draining water from the existing underground structure using a drainage system; A construction method for a drainage structure equipped with the above.

4. At least natural water or less in the existing underground structure is backfilled with carbon dioxide-immobilized concrete or recycled lime. A method for constructing the drainage structure according to claim 3.

Images