JP2001214451A - Ground-water level lowering method and its equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground-water level lowering method with which ground- water level can be lowered efficiently with few collecting and draining facilities when excavation of a deeper area than the ground water level is required, or the area that needs to be lowered is vast, and with which level of ground- water can be lowered where there are obstacles on the surface of the earth. SOLUTION: The lowering of ground-water level is performed by sucking the ground-water with pumps at an edge of a pipe which is protruded on the surface of the earth while one or multiple pipes equipped with collecting parts are inserted horizontally along the ground-water area, and collecting parts are located in the ground-water area. Preferably, multiple pipes should be inserted so that the collecting parts of the pipes inserted into the ground water area can shift toward the axes of the pipes. The lowering the level can be performed efficiently with the minimum number of pipes by inserting multiple pipes into the ground-water area along the area that needs to be lowered like the pipes are surrounding the area even if the area is vast.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for lowering groundwater level, and more particularly, to installing a horizontal well for collecting water in a substantially horizontal direction using a horizontal boring technique and sucking groundwater with a vacuum drainage pump. The present invention relates to a method and a device for lowering a groundwater level by lowering the water level by discharging the water to the ground.

[0002]

2. Description of the Related Art Conventionally, when excavation work is performed on a ground with a high groundwater level to a position lower than the groundwater level,
In order to prevent the influence of groundwater, auxiliary methods such as groundwater drainage method, water stoppage method, chemical liquid injection method, and impermeable method are used. Among them, the well point method, which lowers the groundwater level efficiently by continuously pumping the groundwater by vacuum suction and is lower in cost than other methods, is widely used.

As a conventional well point method, a vertical catchment well is driven from the ground to a predetermined depth in the ground into the ground to be improved, and groundwater is sucked and discharged by a vacuum pump through a pumping pipe to reduce the groundwater level. I'm trying.

In general, it is necessary to excavate a certain area in a construction planning area or the like. Therefore, in order to lower the groundwater level in the groundwater level lowering request area below the excavation depth, a plurality of vertical water collecting areas are usually used. Wells are installed around the excavation area at predetermined intervals.

[0005]

However, in the conventional well point method, if the groundwater level lowering required area is wide or if the ground of the area has poor water permeability, the predetermined water level lowering is maintained within a certain area. Therefore, there is a problem that the number of the vertical collecting wells to be installed increases, and the installation requires labor, time and cost. In addition, the size and quantity of water collection and drainage facilities had to be set in consideration of the construction planning area.

[0006] Further, since there is a limit to the water level drop depth per vertical collecting well, when excavating deeply, 2
It is necessary to use a multi-stage well point construction method in which well points are sequentially installed in three stages, and this also has a problem that the number of vertical collection wells to be installed increases as described above.

[0007] Further, in places where there is an obstacle to the installation of a vertical collecting well, such as a building, in a groundwater level lowering required area, the conventional well point method cannot be adopted.

Accordingly, an object of the present invention is to solve such a conventional problem. Therefore, even when excavation is required to a position deeper than the groundwater level or when the area required for lowering the groundwater level is large, water collection is performed. And a groundwater level lowering method and apparatus capable of efficiently reducing the groundwater level with a small number of drainage facilities and lowering the groundwater level immediately below even if there is an obstacle on the ground surface. Is to do.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method and an apparatus for lowering the groundwater level, and is configured as follows to solve the above-mentioned technical problems. That is, in the method of lowering the groundwater level of the present invention, one or more pipes provided with a water collecting section are inserted substantially horizontally along the groundwater area, and the water collecting section is located in the groundwater area. In this state, groundwater is lowered while suctioning groundwater with a pump from a pipe end protruding above the ground surface. In the groundwater level lowering method of the present invention, it is preferable that a plurality of pipelines are further inserted so that a water collecting portion of the pipeline inserted in the groundwater area is displaced in the pipe axis direction. According to a third aspect of the present invention, in the first aspect, the conduit is an aggregate of a plurality of small diameter tubes housed in a circumscribed circle.

According to the present invention, a plurality of pipelines are inserted into groundwater along the periphery of the groundwater level lowering area so as to bend the area, so that the groundwater level lowering request area is wide. The groundwater level can be efficiently reduced with the minimum number of pipelines. In this case, the ends of the pipelines may be connected on the ground surface.

Further, in the present invention, it is preferable that the start and end of the pipeline are protruded above the ground surface, and a pump is provided at the protruding portion. When a plurality of the pipelines are inserted and inserted, the starting ends and the endings of the plurality of the pipelines are respectively protruded above the ground surface, and the starting ends and the endings of the plurality of the pipelines are connected by a collecting pipe. It is preferable to suction with a pump through the collecting pipe.

As a further feature of the present invention, the pipe is formed of a flexible member, a hollow elastic body is inserted into the pipe, and the elastic body is pressed by a fluid positive pressure applied from the back of the elastic body. Can be cleaned while the pipe is slid in the pipe.

Further, the present invention is preferably configured as follows in order to solve the above technical problem. That is, the underground water level lowering device of the present invention includes a means for inserting a pipeline having a water collecting portion almost horizontally in a groundwater body, and applying a negative pressure to the water collecting portion located in the groundwater region in the previous period to absorb water. A lowering device for lowering the groundwater level, comprising a water absorbing means for performing the above-mentioned step, wherein the conduit is formed of a flexible conduit. Further, the underground water level lowering device of the present invention is characterized in that the water collecting portion provided in the pipe is a multi-hole formed with different hole diameters in the pipe axis direction.

As a water absorbing means of the present invention, a submersible pump is provided in the middle of the pipe, and the water absorbing means is constituted by a two-stage suction action with a vacuum pump provided on the ground surface side.
In a case where the conduit provided with the water collecting portion is a flexible conduit, an expansion means for applying an expansion pressure to an inner peripheral side (radial direction) of the flexible conduit is provided. Is preferred. Furthermore, in the underground water level lowering device of the present invention, when the water collecting portion has a hole diameter in the pipe, it is preferable to install a mesh filter inside.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely illustrative examples unless otherwise specified. Absent.

(First Embodiment) A groundwater level lowering device according to a first embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 7, and 8. FIG. FIG. 1 (a) is a schematic view of the underground water level lowering device when one end of the pipeline is protruded from the surface of the ground and the other end of the pipeline is inserted underground, and FIG. FIG. 1C is a schematic diagram of the underground water level lowering device when both ends of the pipe are projected on the ground surface, and FIG. 1C is a schematic view of the same underground water level lowering device when a submersible pump is installed inside the pipeline. The figures are shown below.

The underground water level lowering device 10 is shown in FIGS.
As shown in (c), a horizontal well 13 is provided, and the horizontal well 13 is formed by inserting the pipeline 1 into a horizontal well having an opening 2 and / or 3 that opens to the ground. In addition, the pipe 1 has a plurality of holes 4 formed in a groundwater area (aquifer) 15 to form a water collecting portion, and the non-porous pipe portions 1c and 1d are provided on the sides of the openings 2 and 3 respectively. positioned. The horizontal well 13 is installed at a depth corresponding to a desired excavation depth and a desired groundwater level drop depth, and the hole drilled in the pipeline 1 in order to maintain a vacuum state in the pipeline. 4 is a groundwater area (aquifer) 1 so as not to be exposed to outside air.
It is preferable that the portion of the pipeline which is installed so as to stay in the inside 5 and is exposed to the outside air due to a decrease in groundwater level is the non-porous pipeline (1c, 1d).

The underground water level lowering device 10 shown in FIGS. 1A to 1C is provided with a vacuum pump 7 in an opening 2 projecting from the surface of the ground. The vacuum pump 7 applies a negative pressure to the hole 4, which is a water collecting part, and sucks groundwater into the pipeline 1, and the sucked groundwater is discharged by a drainage facility (not shown). As one of the embodiments shown in FIG. 1A, the other end 33 of the pipeline is closed to enhance the suction effect. As shown in FIG. 1B and FIG. 1C, the groundwater level lowering device 10 has an opening 3 protruding from the surface of the ground.
Having. In FIG. 1B, the opening 3 is not shown in FIG.
It is designed to be connected to the axial pipeline,
A vacuum pump 8 may be provided as shown in FIG. The operation of the vacuum pump 8 is the same as that of the vacuum pump 7. In this case, the pipe 1 can suck and drain the groundwater more efficiently by the vacuum pumps 7 and 8 installed at both ends. In FIG. 1C, a submersible pump 9 is provided in the pipeline 1. This is because when the groundwater level lowering required area 101 is deep and it is necessary to insert the horizontal well and the pipeline 1 deeply, or when it is difficult to pump the groundwater to the surface with the vacuum pump alone, Pump 9 promotes pumping efficiency of groundwater.

Here, the conduit 1 used in the above-described embodiment will be described. In order to perform vacuum water absorption and water pumping, it is necessary to apply suction force to the pipeline 1 provided with the water collecting portion of the underground water level lowering device 10 of the present embodiment substantially uniformly in the pipeline.

FIG. 2 is a cross-sectional view in the case where the water collecting portion of the pipe inserted in the groundwater area is constituted by a plurality of small diameter pipes inserted so as to be displaced in the pipe axis direction. 2
In the above, the pipe 1 is formed of a plurality of small diameter pipes 5 inserted so as to be displaced in the pipe pipe axial direction, and the groundwater suction force due to the negative pressure is downstream from the upstream side of the groundwater flow in the pipe 1. A configuration is shown in which the components are applied almost equally to the side. Arrow W represents the flow of groundwater. The groundwater sucked in the hole 4 formed in the pipe 1 passes through a small-diameter pipe hole 6 formed in the small-diameter pipe, and is pumped to the ground surface by the vacuum pump installed in the opening. Drained.

FIG. 3 is a sectional view taken along the line AA of the sectional view, and is a sectional view of the pipeline 1 taken along the line AA. In this embodiment, three small-diameter pipes 5 are provided, but it is preferable that the number of the small-diameter pipes is adjusted as necessary. Further, the small-diameter pipes 5 may have different inner diameters depending on the negative pressure applied to the small-diameter pipes and the length of each small-diameter pipe.

FIG. 7 is a schematic view showing a case where the water collecting portions of the pipes are formed with different hole diameters in the pipe axis direction. FIG. 7 shows the embodiment of the present invention, in which the holes 4 provided in the pipe 1 for collecting water are multiple holes formed with different hole diameters in the pipe axis direction. The hole 4 is formed such that the diameter of the hole 4 is increased toward the downstream side of the groundwater flow in the pipe 1, so that the groundwater flows through the hole 4 in the entire length of the pipe 1 in the process of vacuum suction and drainage. This shows a configuration in which the suction force is applied almost uniformly.
The method of sucking, pumping, and draining groundwater by the groundwater level lowering device is the same as described above, and a description thereof will be omitted.

Further, in the present embodiment, the pipe 1
Has a plurality of holes 4, and when the groundwater is sucked, soil smaller than the hole diameter of the holes 4 passes through the holes 4 together with the groundwater, so that the inside of the pipeline 1 which is inserted substantially horizontally Can be clogged. In order to prevent this, FIG. 8 shows a form in which a chip-shaped mesh or a multilayer wound mesh is provided between the inner peripheral side of the pipeline 1 and the outer peripheral side of the inner pipe 19. FIG. 8 is a cross-sectional view of the pipeline when a chip-shaped mesh or a multilayer wound mesh is provided as a filter on the inner peripheral side of the pipeline having a hole diameter of the pipeline. Due to the negative pressure applied by the vacuum pump, the groundwater in the underground water area (aquifer) 15 is sucked through the holes 4 formed in the pipeline 1 and filtered by the mesh filter 20 to remove soil. The groundwater, which has been filtered, flows into the inner pipe 18 through the inner pipe hole 17 formed in the inner pipe 19, and is pumped to the opening and drained.

In the present embodiment, in order to prevent mud clogging in the pipe, a strainer pipe or a porous pipe using a well-known combination of a slit and a hole is used in the present embodiment. And using it as the inner tube 19,
A method of burying filterable sand between the horizontal well 13 and the pipeline 1 in order to prevent not only mud clogging in the pipeline but also a decrease in groundwater permeability due to mud clogging in the hole 4. Alternatively, a method in which the filter material portion is provided on the outer peripheral side of the pipeline 1 may be used. The pipe 1, the small-diameter pipe 5, and the inner pipe 19 used in the present water level lowering device are preferably made of a flexible material such as a plastic material. A flexible member around which a fiber or the like is wound is preferable, but not limited to this.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
It is a top view which shows arrangement | positioning of the groundwater level lowering apparatus which concerns on embodiment. As shown in FIG. 4, the pipe line 1 of the groundwater level lowering device 10 described in the first embodiment is connected along the periphery of the groundwater level lowering request area 101 so as to surround the area 101.
It is inserted in this groundwater area. By connecting the substantial road ends of the pipes 1 projecting on the ground surface with the connecting pipes 30, the water collecting pipes can be made one path, and the suction by the vacuum pump 7 can be performed.
Pumping and draining can be done in one place. The suction, pumping, and draining processes of the groundwater by the groundwater level lowering device 10 of the present embodiment are the same as those of the first embodiment, and thus the description thereof will be omitted.

In the conventional well point method, it is necessary to install a number of vertical collecting wells in the vicinity of the groundwater level lowering required area (digging area) 101 in order to obtain a desired lowering of the groundwater level. Was. However, by inserting the groundwater level lowering device 10 of the present invention substantially horizontally along the periphery of the groundwater level lowering request area 101 so as to bend the area 101,
The required number of pipelines is at least four, and the number of installations per unit area can be reduced as compared with the point arrangement.

The conduit 1 used in the present embodiment is shown in FIG.
The pipe 1 shown in (a) and FIG. 1 (b) may be disposed endlessly along the periphery of the groundwater level request area 101 so as to bend the groundwater level request area 101, and when the connecting pipe 30 is not used. It is necessary to install a vacuum pump and a drainage facility at the substantial roadside openings projecting from the ground surface. In addition, when the excavation depth is deep, and therefore the groundwater level lowering request depth is deep,
As shown in (c), two-stage suction is possible by using the pipe 1 provided with the submersible pump 9 in the pipe, thereby making it possible to extremely economically and efficiently lower the groundwater level. it can.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
It is a top view which shows arrangement | positioning of the groundwater level lowering apparatus which concerns on embodiment. As shown in FIG. 5, three pipes 1 of the groundwater level lowering device 10 described in the first embodiment are inserted underground in the groundwater level lowering required area 101. The start ends and the end ends of the plurality of pipes 1 are respectively protruded on the ground surface, the openings 2 on the start end side are connected to each other by a collecting pipe 31, and the openings 3 on the end side are connected to each other by a collecting pipe 32. Thereby, the vacuum pumps 7, 8 installed in the collecting pipes 31, 32
Suction, pumping and draining are performed. The method of suctioning, pumping, and draining groundwater by the groundwater level lowering device 10 of the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

In the present embodiment, the pipeline 1 of the groundwater level lowering device 10 of the present invention is inserted directly below the groundwater level lowering required area 101. As a result, the groundwater in the groundwater level lowering request area 101 can be reliably lowered to a desired depth without being influenced by the depth of the lowering water level. In the case where the groundwater level in the groundwater level lowering request area 101 is large or in the case of a deep well, a large amount of groundwater needs to be suctioned / pumped and drained in order to lower the groundwater level to a desired level. In this case, it is preferable to insert an appropriate number of the pipes 1 according to the amount of suction of the groundwater. further,
When an obstacle 55 as shown in FIG. 1C is present on the ground surface in the groundwater level lowering required area 101, the conventional vertical collecting well cannot be adopted. However, in the embodiment of the present embodiment, since the underground water level lowering device 10 of the present invention can be inserted under the obstacle 55 under the ground,
The groundwater level in the groundwater level lowering required area 101 can be lowered.

(Fourth Embodiment) FIG. 6 shows a cross section of the present embodiment, and shows a method of cleaning the inside of the pipeline 1 of the underground water level lowering device 10. When the pipe 1 has a plurality of perforated holes 4, as described in the first embodiment, there is a possibility that mud clogging occurs in the pipes and the holes.
Even if the means for preventing mud clogging are provided as described above, some mud clogging cannot be avoided. In the present embodiment, the pipe 1 is formed of a flexible member, a hollow elastic body 22 is inserted into the pipe, and a fluid is applied to the elastic body from the back side to apply a positive pressure to the elastic body. The inside of the pipeline and the inside of the hole are washed while sliding 22 in the pipeline.

When a balloon-like elastic body is used as the hollow elastic body 22, it is desirable to protect the surface of the hollow elastic body 22 with a net 23 in order to prevent breakage, and further use the net 23. By the net 2
The hole 3 enters the hole 4 from the inner peripheral surface of the pipe 1, and the details of the hole can be washed. As means for moving the hollow elastic body 22 in the pipe, in addition to using the application of a positive fluid pressure,
There is also a means for attaching a wire or the like to the hollow elastic body 22 and drawing and moving the wire into the conduit.

[0032]

As described above, according to the method and the apparatus for lowering the groundwater level of the present invention, in the groundwater level lowering requested area, the pipe provided with the water collecting part is formed in a substantially horizontal direction along the groundwater area. One or more pipes are inserted, and a vacuum pump is installed in an opening protruding above the surface of the pipeline, and groundwater is pumped to the ground and drained to lower the water level to a desired groundwater level.

Moreover, by inserting the pipeline having the water collecting portion in a substantially horizontal direction, the number of water collecting pipelines per unit area can be reduced as compared with the case where a conventional vertical water collecting well is used. In excavation work where the groundwater level must be lowered,
The labor and time required for the work of lowering the groundwater level and, as a result, the construction cost can be reduced. further,
Even if there is an obstacle on the ground surface in the groundwater level lowering requested area and it is not possible to use the conventional vertical collecting well of the well point method, the groundwater level lowering device of the present invention is inserted directly under the obstacle. And the groundwater level can be lowered.

[Brief description of the drawings]

FIG. 1 is a schematic view of a groundwater level lowering device according to a first embodiment of the present invention, in which (a) projects one end of a pipeline to the ground surface and the other end of the pipeline to an underground. It is a schematic diagram of the same groundwater level lowering device when it is inserted, (b) is a schematic diagram of the same groundwater level lowering device when both ends of the pipe are protruded from the ground, and (c) is the same. It is the schematic of the underground water level lowering apparatus at the time of installing a submersible pump inside a pipeline.

FIG. 2 is a cross-sectional view in a case where a water collecting portion of the pipeline inserted in a groundwater area is constituted by a plurality of small-diameter pipes inserted so as to be displaced in a pipe axis direction.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

FIG. 4 is a plan view showing an arrangement of a groundwater level lowering device according to a second embodiment of the present invention.

FIG. 5 is a plan view showing an arrangement of a groundwater level lowering device according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a fourth embodiment of the present invention, showing a method of cleaning a pipeline inside the pipeline 1 of the groundwater level lowering device 10.

FIG. 7 is a schematic view showing a case where the water collecting portions of the pipes of the respective embodiments are formed with different hole diameters in the pipe axis direction.

FIG. 8 is a cross-sectional view of the pipeline in which a chip-shaped mesh or a multilayer wound mesh is provided on the inner peripheral side of the pipeline having a hole diameter of each of the embodiments.

FIG. 9 is a schematic view of a conventional well point method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipeline 1a Pipeline part (above the ground surface) 1b Pipeline part (below the ground surface) 1c, 1d Non-porous conduit part 2, 3 Opening part 4 Hole 5 Small diameter pipe 6 Small diameter pipe hole 7, 8 Vacuum pump 9 Submersible pump 10 Groundwater level lowering device 13 Horizontal well 15 Groundwater area (aquifer) 17 Inner pipe hole 18 Inner pipe 19 Inner pipe 20 Mesh filter 22 Hollow elastic body 23 Net 30 Connecting pipe 31, 32 Collecting pipe 33 Pipe end 45 Soil 55 Obstacle 81 Pumping pipe 85 Vertical catchment well 101 Groundwater drop request area (digging area) W Groundwater flow direction

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Katsuta Riki 5-22-27 Higashi-Gotanda, Shinagawa-ku, Tokyo Within the territory of the Company Limited (72) Inventor Makoto Nishigaki 2-1-1 Tsushimanaka, Okayama City, Okayama Prefecture Okayama University Faculty of Environmental Science and Engineering

Claims (13)

[Claims] At least one pipeline including a water collecting section is inserted substantially horizontally along a groundwater area, and is protruded from the surface of the ground with the water collecting section positioned in the groundwater area. A method for lowering the groundwater level, wherein the groundwater is lowered while suctioning groundwater with a pump from the end of the pipe. 2. The method according to claim 1, wherein a plurality of pipelines are inserted so that the pipeline collecting part located in the groundwater area is displaced in the pipe axis direction. 3. The method according to claim 1, wherein the pipe is an aggregate of a plurality of small diameter pipes housed in a pipe circumcircle. 4. The method according to claim 1, wherein a plurality of pipelines are inserted into the groundwater area along the periphery of the area so as to bend the groundwater level request area. 5. The method according to claim 4, wherein substantial road ends of the pipelines are connected on the ground surface. 6. The method according to claim 1, further comprising projecting the start and end of the pipeline along the ground surface, and suctioning the ground with a pump provided at at least one of the projecting portions. 7. A start end and an end of each of the plurality of pipelines are respectively protruded above the ground surface, and the start and end of each of the plurality of pipelines are connected to each other by a collecting pipe, and a pump is connected through the collecting pipe. The method for lowering groundwater level according to claim 1, wherein the suction is performed. 8. The pipe is formed of a flexible member, a hollow elastic body is inserted into the pipe, and the elastic body is slid in the pipe by a positive fluid pressure applied from a back surface of the elastic body. 2. The method for lowering groundwater level according to claim 1, wherein the cleaning of the pipeline is performed while the cleaning is performed. 9. A means for inserting a pipeline having a water collecting section substantially horizontally in a groundwater area, and a water absorbing means for applying a negative pressure to the water collecting section located in the groundwater area to absorb water. A groundwater level lowering device, wherein the pipe is formed of a flexible pipe. 10. The groundwater lowering device according to claim 9, wherein the water collecting portion provided in the pipe is a multi-hole formed with different hole diameters in the pipe axis direction. 11. The underground water level lowering device according to claim 9, wherein a submersible pump is provided in the middle of the pipeline, and a water suction means is constituted by a two-stage suction action with a pump provided on the ground surface side. 12. The underground water level lowering device according to claim 9, further comprising expansion means for radially urging the expansion pressure from the inner peripheral side of the flexible conduit. 13. The groundwater level lowering device according to claim 9, wherein a mesh filter is provided on the inner peripheral side of the pipe having a hole diameter.