JP3650809B2 - Water flow hole forming apparatus and method for forming water flow holes used for water flow hole formation for maintaining groundwater flow in impermeable walls - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water flow conservation technique for a groundwater flow that is blocked by a water shielding wall for constructing an underground part of a civil engineering or building structure. The present invention relates to a water hole forming apparatus and a method thereof.
[0002]
[Prior art]
When building a linear underground structure such as a subway or an underground road, if a deep wall is constructed continuously, free groundwater flow in the area may be blocked. FIG. 7 is a schematic diagram showing a state where the groundwater flow is blocked by the water blocking walls 100a and 100b. Here, the impermeable walls 100a and 100b are deeper than the flooring 107 in order to stabilize the excavation bottom ground, and are long penetrations 108 penetrating the permeable layers 105a and 105b to the impermeable layer 106b. For this reason, the groundwater flow 160a, 160b is blocked by the upstream impermeable wall 100b.
[0003]
When the groundwater flow 160a, b is blocked by the water-impervious walls 100a, b, the ground surface 150a on the downstream side causes ground subsidence due to a decrease in the groundwater level. Further, the fall of the groundwater level causes the standing tree 130a to wither and the well 120 to wither. Further, there is an influence such as settlement of the structure 110a such as a building.
[0004]
On the upstream side of the water-impervious wall 100b, the water level rises due to the blocking of the groundwater flow, and the wetness of the ground on the upstream surface 150b causes the root decay of the standing tree 130b, or the underground portion of the structure 110b. Water leakage may occur. In addition, since the circulation of groundwater flow is lost, the quality of the groundwater itself may deteriorate. Such influence on the surrounding environment appears during construction.
[0005]
Further, the impermeable walls 100a and 100b pass through the permeable layer 105b deeper than the flooring 107 so that the flooring 107 does not cause a floating phenomenon in which the underground structure floats due to the groundwater underneath. 106b is incorporated. For this reason, the underground water flow 160b deeper than the flooring 107 to be excavated for the construction of the structure is also blocked.
[0006]
In order to solve the above-mentioned problems, a method of restoring the groundwater flow at the top of the structure by removing the impermeable wall at the top of the structure after completion of the underground structure.
A method of drilling the wall surface of the cut-off part of the impermeable wall, inserting a water collecting pipe into the upstream permeable layer ground, and connecting it with the drain pipe inserted into the downstream permeable layer ground to restore the groundwater flow.
There is known a method of recovering a groundwater flow by digging a drainage well on both sides of the cut-off portion of the impermeable wall and connecting an upstream well and a downstream well in the ground.
However, in these groundwater flow maintenance methods, there is a problem that the groundwater flow 160a in the upper part of the flooring 107 that has been cut can be restored, but the groundwater flow 160b in a portion deeper than the flooring 107 cannot be restored.
[0007]
In addition, there is a problem that maintenance costs such as clogging of wells after construction are expensive.
[0008]
The inventor proposed in Japanese Patent Application No. 2000-205456 a mountain retaining wall having a groundwater flow maintenance function for forming a water passage at an arbitrary time and a construction method thereof for solving the above-mentioned problem. However, it takes time to break the anode of the pile core material that requires strength, and it is necessary to crush the solidified soil mortar that surrounds the pile core material, which makes it difficult to form reliable water holes. .
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned problems, and is blocking the groundwater flow for the maintenance of the groundwater flow blocked by the soil mortar impervious wall that is constructed in the construction of the underground excavation structure. It is an object of the present invention to provide a water passage hole forming device and a water passage hole forming method for forming a water hole at an arbitrary time in a water shielding wall portion.
[0010]
In particular, the present invention provides a water-hole forming device that can easily and economically form water-holes at an arbitrary depth of a soil mortar impermeable wall.
[0011]
Moreover, the water-hole forming apparatus which can purify the harmful substance of a groundwater flow after water-hole formation is provided.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the water-hole forming device used for groundwater flow maintenance water-hole formation of the water-impervious wall according to claim 1 is a groundwater flow blocked by a water-impervious wall constructed when constructing an underground excavation structure. For the maintenance of the water-permeable wall forming device provided as a pile core material of the water-impervious wall in order to form a water-permeable hole at any time in the portion where the water-impervious wall blocks the groundwater flow,
The water flow hole forming device is a pile core hollow steel pipe whose top and bottom are hermetically sealed, and a water stop chamber partitioned by an internal partition at the center of the steel pipe, and both sides partitioned by the water stop chamber are added from the ground. A pressure chamber connected to a pressure pipe for supplying a pressurized solution, a water passage hole opened to the outside from the pressure chamber, an expansion rupture portion provided to close the water passage hole, and the internal A communication hole that is opened in the partition wall, and a water stop gate that is provided so as to close the communication hole and that can be pulled out upward in the water stop chamber;
The expansion and rupture portion includes an elastic material that expands outward due to the pressure of the pressurized solution in the pressure chamber and ruptures and opens the water passage hole when the expansion limit is reached.
[0013]
The water flow hole forming device used for forming the water flow hole for protecting the groundwater flow of the water barrier wall according to claim 2 is used for the maintenance of the groundwater flow blocked by the water shield wall constructed when the underground excavation structure is constructed. In order to form a water passage hole at any time in the part where the water wall blocks the groundwater flow, it is connected to the upper and lower pile cores so that the water blocking wall is located at a depth that blocks the groundwater flow. A water hole forming device,
The water flow hole forming device closes the communication hole, two upper and lower pressure chambers connected to a pressure pipe for supplying a pressurized solution from the ground, a communication hole opened in an adjacent partition wall of the upper and lower pressure chambers. In this way, the electrolytic corrosion partition provided insulated from the partition wall and connected to the electrode wire, the water passage hole opened to the outside from each of the pressure chambers, and the expansion rupture part provided to close the water passage hole, Consisting of
The expansion rupture part is formed of an elastic material that expands outward due to the pressure of the pressurized solution in the pressure chamber and ruptures to open the water passage hole when the expansion limit is reached. .
[0014]
The invention described in claim 3 is the invention described in claim 1 or 2, characterized in that the elastic material of the expansion rupture portion is a rubber plate.
[0015]
Invention of Claim 4 is invention in any one of Claim 1, 2, or 3, Comprising: The said water stop chamber is a filter which filters the harmful substance of a groundwater flow, when a water flow hole is formed. It is characterized by being filled with a material.
[0016]
According to the invention of claim 5, in order to preserve the groundwater flow blocked by the impermeable wall constructed during the construction of the underground excavation structure, the portion where the impermeable wall blocks the groundwater flow is passed at any time. A water hole forming method using the water hole forming device according to claim 1 provided as a pile core material of a water shielding wall to form a water hole,
Pile core material is built in the impermeable wall and filled with soil mortar. During curing of the soil mortar, the pressurized solution is filled into the pressure chamber from the pressure pipe, and the expansion and rupture part is pushed out of the pressure chamber to surround the surrounding area. The soil mortar is eliminated, and the water passage hole is opened by rupturing at the expansion limit, and then the water stop gate is pulled out from the ground at any time to open the communication hole so that the water can pass therethrough.
[0017]
According to the sixth aspect of the present invention, in order to preserve the groundwater flow blocked by the impermeable wall constructed when the underground excavation structure is constructed, it is possible to pass through the portion where the impermeable wall blocks the groundwater flow at any time. The water-flow hole using the water-hole forming apparatus according to claim 2, wherein the water-blocking wall is connected to upper and lower pile core members so as to be positioned at a depth at which the groundwater flow is blocked in order to form a water hole. A forming method comprising:
Pile core material is built in the impermeable wall and filled with soil mortar. During curing of the soil mortar, the pressurized solution is filled into the pressure chamber from the pressure pipe, and the expansion and rupture part is pushed out of the pressure chamber to surround the surrounding area. While removing the soil mortar and rupturing at the expansion limit to open the water passage hole, then filling the pressure chamber with the electrolyte solution through the pressure pipe at any time, the negative electrode of the DC power supply to the pile core material, By connecting a positive electrode to the electrolytic corrosion partition and applying a voltage, the electrolytic corrosion partition is dissolved in an anode so that water can flow through the upper and lower pressure chambers.
The invention according to claim 7 is the method of forming a water passage hole according to claim 5 or 6, wherein after allowing water to pass, the water stop chamber or the pressure chamber is filled with a filter material, and harmful substances in the groundwater flow are filtered. It is characterized by that.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1: shows the structure of the water flow hole formation apparatus of the 1st Embodiment of this invention, (a) is a front view, (b) is side sectional drawing.
[0020]
1 (a), a pile core hollow steel pipe 20 is hermetically sealed by a sealing lid 21 fixed to the upper portion thereof by a sealing bolt 21b and a bottom plate 29 provided at the bottom. A pressure pipe 3a is connected to the lid 21 via a valve 3b. In addition, the pile core hollow steel pipe 20 that is placed is provided with a water passage hole 1 that is blocked by an expansion rupture portion 22 at a position where the groundwater flow is blocked. The expansion and rupture portion 22 is configured such that the elastic material 23 such as a rubber plate is fastened to the pile core hollow steel pipe 20 with a screw 23b by an elastic material fixing frame 23a and the water passage hole is blocked.
[0021]
FIG. 1B is a diagram illustrating a cross-section of the water flow hole forming device 10. The pile core hollow steel pipe 20 has a water stop chamber 25 partitioned by internal partition walls 27 and 27, and pressure chambers 24 and 24 connected to both sides of a pressure pipe 3a for supplying a pressurized solution from the ground. A water passage hole 1 opened to the outside from the pressure chamber 24, an expansion rupture portion 22 provided so as to close the water passage hole 1, and a communication hole 2 opened in the internal partition wall 27 of the water stop chamber 25. And a water stop gate 2a which is provided so as to close the communication hole 2 and can be pulled out at the top.
[0022]
The water stop gate 2a is formed in a size that closes the opening of the communication hole 2, and is a rubber plug that seals the communication hole 2. A pull-out rod 2b for opening the gate for lifting from the ground is connected to the pull-out rod 2b. It extends to the upper part of the pile core hollow steel pipe 20.
[0023]
Next, the water passage hole 1 portion will be described in detail with reference to FIG. Fig.2 (a) shows the AA cross section of FIG.1 (b). The inside of the pile core hollow steel pipe 20 is partitioned into a water stop chamber 25 partitioned by internal partition walls 27, 27 at the center, and pressure chambers 24 on both sides thereof.
[0024]
The pressure chamber 24 is provided with a water passage hole 1 that opens to the outside, and is closed by an expansion rupture portion 22.
Further, the water stop chamber 25 is provided with a communication hole 2 opened to the internal partition wall 27 and is closed by a water stop gate 2a.
[0025]
The expansion rupture portion 22 has a configuration in which an elastic material 23 such as a rubber plate having a size covering the water passage hole 1 is fixed to the pile core hollow steel pipe 20 with an elastic material fixing frame 23a with a screw 23b.
[0026]
FIG. 2B is a diagram illustrating a state in which the pressure chamber 24 is pressurized. By injecting pressurized water through the pressurized pipe 3a, the elastic member 23 of the expansion rupture portion 22 expands and expands outward. When it expands outside, it works to push away the solidified soil mortar 45 (see FIG. 3) filled in the surroundings, and when further pressurized, it bursts beyond the expansion limit. The state of the expansion limit is illustrated by a virtual line.
[0027]
FIG. 3 is a cross-sectional view showing a water hole forming state by the water hole forming apparatus 10 of the present invention disposed on the water shielding wall 100. Usually, the H-shaped steel 40 is used as the pile core in the water-impervious wall 100, but the water-hole forming device 10 is installed in a place where the groundwater flow is blocked, and the water-hole is formed at a position where the water-permeable layer 105 is blocked. 1 is provided. In the figure, the elastic member 23 of the expansion rupture portion 22 (see FIG. 2) bursts beyond the expansion limit to open the water passage hole 1, and the water stop gate 2a of the water stop chamber 25 shown in FIG. The state where the hole 2 is opened and the groundwater flow 160 can pass is shown. In the figure, 45 indicates a soil mortar poured around the pile core. 46 is a small gravel filled in the pressure chamber, and 47 is a filter material for water purification filled in the water stop chamber. After the water passage hole 1 and the communication hole 2 are opened, the sealing lid 21 is removed and the material is introduced from the ground. Fill.
[0028]
Next, the formation process of the water hole using the water hole forming apparatus 10 of the present invention will be described with reference to FIG. The reference numerals will be described with reference to FIGS. First,
(1) Excavate the location of the impermeable wall. An excavation hole 50 is shown.
(2) The water-hole forming device 10 of the present invention is installed in a drilling hole as a pile core material.
(3) Pour the soil mortar 45 around the pile core.
(4) During the curing of the soil mortar 45, the above-mentioned pressurized solution supply device 3 is operated, and pressurized water is supplied through the pressurized pipe 3a. Due to the pressure in the pressure chamber 24, the elastic material 23 of the expansion rupture portion 22 pushes and expands the external soil mortar 45.
(5) The elastic member 23 is ruptured at the expansion limit and the water passage hole 1 is opened. Here, the natural mountain permeable layer and the pressure chamber are in a water-permeable state.
(6) When the groundwater flow is restored, the water stop gate 2a in the water stop chamber 25 is withdrawn from the ground, and the communication hole 2 is opened to form a groundwater flow path, thereby maintaining the groundwater flow.
(7) Further, by filling the pressure chamber 24 with a water-permeable material such as small gravel 46 and the water-stopping chamber 25 with a water purification filter material 47 from the ground, the groundwater flow is purified to restore the water flow.
[0029]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5A is a cross-sectional view of the water passage forming device 10A of the second embodiment. In this embodiment, the H-shaped steel 40 generally provided as a pile core material of the soil mortar impermeable wall 100 (see FIG. 3) is provided with the pile core material connecting portions 26 on both sides of the rectangular water-hole housing 20A. It has a structure that can be connected and buried in the underground permeable layer.
[0030]
The water passage housing 20A is divided into upper and lower parts by adjacent partition walls 28 to form pressure chambers 24, 24. The upper and lower pressure chambers 24 are connected to a pressurized pipe 3a for supplying a pressurized solution from the ground. In addition, the adjacent partition wall 28 is provided with a communication hole 2 that is opened and an electrolytic corrosion partition wall 28 a that closes the communication hole 2. The electrolytic corrosion partition wall 28a is fixed via an insulating material 28b for insulating the adjacent partition wall 28, and is connected to the electrode wire 13 inserted through the pressurized pipe 3a.
[0031]
The pressure chamber 24 is provided with a water passage hole 1 that opens to the outside, and the water passage hole 1 is closed by an expansion rupture portion 22. The expansion rupture portion 22 has a configuration in which an elastic material 23 such as a rubber plate covering the water passage hole 1 is fixed to the water passage housing 20A with an elastic material fixing frame 23a with a screw.
[0032]
The water flow holes 1 of the upper and lower pressure chambers 24, 24 are provided in opposite directions so that one opens to the ground and one opens to the excavation side.
[0033]
FIG.5 (b) is a schematic diagram which shows the construction process of the water flow hole formation apparatus of 2nd embodiment. Excavation, installation of pile core material with water hole forming device 20A, pouring of soil mortar 45, filling of pressure chamber 24 with pressure water during curing of soil mortar 45, separation of soil mortar by expansion rupture part 22, rupture of elastic material 23 The opening of the water passage hole 1 due to is the same process as (1) to (5) in FIG. 4 of the description of the first embodiment, so that the description thereof is omitted.
[0034]
Next, at the time of recovery of an arbitrary groundwater flow, the electrolyte solution 4 is filled into the pressure chamber 24 from the pressurized solution supply device 3, and the negative electrode and the H shape are applied to the electrolytic corrosion partition wall 28 a from the ground DC power supply 5 through the electrode wire 13. By connecting a positive electrode to the pressure chamber through steel and applying a voltage, the electrolytic corrosion partition wall 28a (FIG. 5 (a)) is broken by anodic dissolution and the communication hole 2 (FIG. 5 (a)) is opened.
[0035]
A groundwater flow path from the water passage hole 1 of the upper and lower pressure chambers 24 that has already been opened is formed, and the groundwater flow is maintained.
[0036]
Furthermore, the groundwater flow can be purified and restored by filling the pressure chamber 24 with the purified water filter material from the ground via the pressurized pipe 3a. (See Fig. 5 (a))
[0037]
Drawing 6 is a mimetic diagram showing the restoration situation of a groundwater flow after construction of a water hole by a water hole formation device of the present invention.
[0038]
During construction, the underground structure 110c is built in a state where the water is blocked by the water-impervious walls 100, 100, and the upper part of the opened structure 110c is backfilled. As shown in the figure, the water passage hole 1 is penetrated through the water-impervious wall 100 in contact with the water permeable layer 105a, and the groundwater flow 160a is restored by arranging and filling the water passage pipe 30.
[0039]
Further, the water passage hole 1 in contact with the water permeable layer 105b deeper than the flooring 107 restores the groundwater flow 160b. These water holes can be formed according to the progress of the construction and the time required to recover the groundwater flow.
[0040]
In the above embodiment, the pile core hollow steel pipe 20 has been described as a prismatic steel pipe, but it may be either a cylindrical shape or a polygonal shape as long as the inside is hollow.
[0041]
【The invention's effect】
The water-hole forming device used for groundwater flow maintenance water-hole formation according to the present invention can easily and economically form a water-hole in the water-impervious wall provided in the water-permeable layer after the construction of the underground structure. it can. In particular, a water passage hole can be formed at an arbitrary depth and position of the impermeable wall.
[0042]
Moreover, since a water passage hole to the permeable layer ground can be formed during the curing of the soil mortar, reliable groundwater flow maintenance can be performed.
[0043]
In addition, by forming a water flow channel with the outside in advance, pulling out the water stop gate or dissolving the electrolytic corrosion partition into the anode and opening the communication hole at any time, more reliable control of groundwater flow recovery is possible. Can be done.
[0044]
Furthermore, since a water purification filter can be arrange | positioned in a pressure chamber or a water stop chamber, water quality purification can be performed with the restoration | recovery of a groundwater flow.
[Brief description of the drawings]
FIG. 1 shows a configuration of a water passage forming device according to a first embodiment of the present invention, wherein (a) is a front view and (b) is a cross-sectional view.
2A is a cross-sectional view taken along the line AA of FIG. 1B, and FIG. 2B is a cross-sectional view illustrating a state where the pressure chamber of FIG.
FIG. 3 is a cross-sectional view showing a water hole forming state by the water hole forming apparatus of the present invention disposed on the water shielding wall.
FIG. 4 is a schematic view showing a water flow hole forming process of the present invention.
5A is a cross-sectional view of a water passage forming device according to a second embodiment of the present invention, and FIG. 5B is a schematic diagram showing a construction process of the second embodiment.
FIG. 6 is a schematic diagram showing a state of restoration of a groundwater flow after construction of a water passage by the water passage forming device of the present invention.
FIG. 7 is a schematic diagram showing a state where a groundwater flow is blocked by a water blocking wall.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Water flow hole 2 Communication hole 2a Water stop gate 2b Pull-out rod for gate opening 3 Pressurized solution supply device 3a Pressurized pipe 3b Valve 4 Electrolyte solution 5 DC power supply 10, 10A Water flow hole forming device 13 Electrode electric wire 20 Pile core hollow Steel pipe 20A Water passage housing 21 Sealing lid 21b Sealing bolt 22 Expansion rupture part 23 Elastic material (rubber plate)
23a Elastic material fixing frame 23b Screw 24 Pressure chamber 25 Water stop chamber 26 Pile core connecting part 27 Internal partition wall 28 Adjacent partition wall 28a Electrical corrosion partition wall 28b Insulation material 29 Bottom plate 30 Water pipe 40 H-section steel 45 Soil mortar 46 Small gravel 47 Filter material 50 Excavation holes 100, 100a, 100b Impermeable walls, soil mortar impermeable walls 105, 105a, 105b Permeable layers 106, 106a, 106b Impervious layers 160a, 160b Groundwater flow 107 Flooring 108 Rooting 110a, 110b, 110c Structure 130, 130a, 130b Standing trees 150, 150a, 150b Ground surface, ground part

Claims (7)

In order to preserve the groundwater flow that is blocked by the impermeable walls that are constructed during the construction of the underground excavation structure, it is necessary to form a water passage hole at any time in the part where the impermeable walls block the groundwater flow. A water hole forming device provided as a pile core material for water walls,
The water flow hole forming device is a pile core hollow steel pipe whose top and bottom are hermetically sealed, and a water stop chamber partitioned by an internal partition at the center of the steel pipe, and both sides partitioned by the water stop chamber are added from the ground. A pressure chamber connected to a pressure pipe for supplying a pressurized solution, a water passage hole opened to the outside from the pressure chamber, an expansion rupture portion provided to close the water passage hole, and the internal A communication hole that is opened in the partition wall, and a water stop gate that is provided so as to close the communication hole and that can be pulled out upward in the water stop chamber;
The expansion and rupture part includes an elastic material that expands outward due to the pressure of the pressurized solution in the pressure chamber and ruptures and opens the water passage hole when the expansion limit is reached. Water hole forming device used for groundwater flow conservation water hole formation. In order to preserve the groundwater flow blocked by the impermeable wall constructed during the construction of the underground excavation structure, in order to form a water passage at any time in the part where the impermeable wall blocks the groundwater flow, A water-hole forming device arranged in connection with the upper and lower pile cores so that the water-impervious wall is located at a depth at which groundwater flow is blocked,
The water flow hole forming device closes the communication hole, two upper and lower pressure chambers connected to a pressure pipe for supplying a pressurized solution from the ground, a communication hole opened in an adjacent partition wall of the upper and lower pressure chambers. In this way, the electrolytic corrosion partition provided insulated from the partition wall and connected to the electrode wire, the water passage hole opened to the outside from each of the pressure chambers, and the expansion rupture part provided to close the water passage hole, Consisting of
The expansion rupture part is formed of an elastic material that expands outward due to the pressure of the pressurized solution in the pressure chamber and ruptures to open the water passage hole when the expansion limit is reached. A water hole forming device used to form a water flow hole for maintaining a groundwater flow in the impermeable wall. 3. The water hole forming apparatus used for forming a groundwater flow maintenance water hole in a water shielding wall according to claim 1, wherein the elastic material of the expansion rupture portion is a rubber plate. The water blocking wall according to any one of claims 1, 2, and 3, wherein the water blocking chamber is filled with a filter material that filters harmful substances in a groundwater flow when a water passage hole is formed. Water hole forming device used for groundwater flow conservation water hole formation in Japan. In order to preserve the groundwater flow that is blocked by the impermeable walls that are constructed during the construction of the underground excavation structure, it is necessary to form a water passage hole at any time in the part where the impermeable walls block the groundwater flow. A water hole forming method using the water hole forming device according to claim 1 provided as a pile core material of a water wall,
Pile core material is built in the impermeable wall and filled with soil mortar. During curing of the soil mortar, the pressurized solution is filled into the pressure chamber from the pressure pipe, and the expansion and rupture part is pushed out of the pressure chamber to surround the surrounding area. The soil mortar is eliminated, and the water passage hole is opened by rupturing at the expansion limit, and then the water stop gate is pulled out from the ground at any time to open the communication hole and allow water passage. Water hole forming method. In order to preserve the groundwater flow blocked by the impermeable wall constructed during the construction of the underground excavation structure, in order to form a water passage at any time in the part where the impermeable wall blocks the groundwater flow, The water-hole forming method using the water-hole forming device according to claim 2, wherein the water-blocking wall is connected to upper and lower pile core members so as to be positioned at a depth at which groundwater flow is blocked.
Pile core material is built in the impermeable wall and filled with soil mortar. During curing of the soil mortar, the pressurized solution is filled into the pressure chamber from the pressure pipe, and the expansion and rupture part is pushed out of the pressure chamber to surround the surrounding area. While removing the soil mortar and rupturing at the expansion limit to open the water passage hole, then filling the pressure chamber with the electrolyte solution through the pressure pipe at any time, the negative electrode of the DC power supply to the pile core material, A method for forming a water passage hole, wherein a positive electrode is connected to the electrolytic corrosion partition wall and a voltage is applied, whereby the electrolytic corrosion partition wall is dissolved in an anode so that water can flow through the upper and lower pressure chambers. 7. The method for forming a water passage hole according to claim 5 or 6, wherein after allowing water to pass, the water stop chamber or the pressure chamber is filled with a filter material, and harmful substances in the groundwater flow are filtered. Or the water-hole formation method of 6.

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