JP2004116152A - Deep well method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply cope with a case in which water cannot be collected sufficiently. <P>SOLUTION: In a deep well method, a lifting pump 12 is installed in a casing 10 buried in a ground, and collected groundwater is pumped up by operating the pump 12. The pump 12 is arranged in the casing 10 in a freely vertically movable manner, and supported to a cylindrical cut-off wall 24 in which a diameter is expanded and contracted freely. The diameter of a packer 24b is expanded, and the pump 12 is operated and a pumping-up is conducted under the state in which the inside of the casing 10 on the side deeper than the depth of the casing is sealed hermetically and closed. When water is pumped up, negative pressure is generated in a section closed by the wall 24, and water can be collected forcibly and efficiently into the casing 10 through a strainer section 18 from the peripheral ground. When a groundwater level is lowered by the pumping-up and reaches the lower end or lower of the wall 24, the operation of the pump 12 is stopped, the packer 24b is shrunk, and moved downwards, the diameter of the packer 24b is expanded again, a new closing region is manufactured and the pump 12 is operated and water is pumped up. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a deep well method.
[0002]
[Prior art]
When the groundwater level in the ground is deep, a deep well method is known as a method used to lower the groundwater level, or to reduce the pressure of the water to be confined or to improve the soft ground. (See Non-Patent Document 1)
[0003]
FIG. 4 shows a typical example of the deep well method. In the construction method shown in the figure, a drilling hole 1 is formed in the ground by an earth auger method or the like, and a casing 2 is embedded in the drilling hole 1.
[0004]
At this time, the space between the casing 2 and the excavation hole 1 is filled with pea gravel, crushed stone, or the like to form the filter layer 3. In the casing 2, a slit 4 in the form of an elongated rectangular hole is previously formed through the casing 2, and the outer periphery thereof is covered with a screen 5, thereby forming a strainer 6 for taking in groundwater into the lower part of the casing 2. .
[0005]
When the installation of the casing 2 is completed, the pump 7 is installed inside the casing 2, and the groundwater collected in the casing 2 is pumped out by the operation of the pump 7.
[0006]
Although such a deep well method is a method that is suitable for a wide range of construction, when a large decrease in groundwater level is required, or when a large amount of water is pumped on a ground with high permeability, However, there was a technical problem described below.
[0007]
[Non-patent document 1]
Published by the Industrial Research Institute Co., Ltd. Encyclopedia Publishing Center, encyclopedia of civil engineering, August 10, 1988, p339-340
[0008]
[Problems to be solved by the invention]
That is, in the deep well method shown in FIG. 4, for example, when the water permeability is smaller than an assumed value, water collection into the casing 2 becomes insufficient, and a predetermined decrease in water level cannot be obtained. .
[0009]
As a countermeasure in such a case, a new drilling well (additional drilling well) is required, but such a countermeasure has a problem that the construction period and construction cost are significantly increased. As a method of lowering the groundwater level, other than the deep well method, for example, {1}. A vacuum well method in which an upper lid is provided at the top end of the casing and the inside of the casing is evacuated with a vacuum pump to forcibly collect groundwater from the strainer section, and (2). In this vacuum well method, a super well point method for restricting the inflow of air into the casing, and (3). There is a negative pressure type deep well method in which negative pressure is generated in the casing and water collection is strengthened by the negative pressure, and it is conceivable to adopt such a method as a countermeasure when the above-described inconvenience occurs. .
[0010]
However, in the methods (1) and (2), a vacuum pump or the like is required, and the equipment becomes excessively large. In an urban area, the noise of the vacuum pump becomes a problem. Further, in the method (3), when the groundwater level drops to the strainer portion, there is a problem that the negative pressure does not work in the casing and the water collecting capacity is reduced.
[0011]
The present invention has been made in view of such a conventional problem, and an object thereof is to simplify the case where the hydraulic conductivity of the ground is smaller than an assumed value and sufficient water collection cannot be performed. An object of the present invention is to provide a deep well method capable of coping with the above.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a hollow cylindrical casing provided with a strainer section for taking in groundwater on a lower side, buried in the ground, and installing a pumping pump in the casing, In the deep well method in which groundwater collected in the pump is pumped to the ground side by operating the pump, the pump is disposed in the casing so as to be movable up and down, and has a cylindrical shape capable of expanding and contracting. Supported by a shielding wall, expanding the shielding wall, closing the inside of the casing at a deeper side to pump water, and pumping down the groundwater level. Was interrupted, the shielding wall was contracted and moved downward along the casing, and thereafter, the shielding wall was re-expanded to pump water.
[0013]
According to the deep well method configured as described above, the water pump is disposed in the casing so as to be movable up and down, is supported by a cylindrical shielding wall capable of expanding and contracting, and expands the shielding wall. Pumping is performed by closing the casing at the deeper side.
[0014]
According to such a pumping method, when the groundwater in the casing is pumped, a negative pressure is generated in the portion closed by the shielding wall, and the negative pressure forces the surrounding ground into the casing via the strainer portion. Water can be collected efficiently and efficiently.
[0015]
Therefore, even if the hydraulic conductivity of the ground is smaller than the initial plan and the water collection in the casing is insufficient, the water can be collected from a wide area by the negative pressure, so that it is not necessary to take any special measures.
[0016]
On the other hand, if pumping is continued, the groundwater level will drop due to pumping, and if this falls below the impermeable wall, air will flow into the casing closed by the impermeable wall, and the negative pressure will decrease. However, in such a state, the pumping is interrupted, the shielding wall is contracted and moved downward along the casing, and then the shielding wall is re-expanded to pump water. It is possible to avoid a decrease in the water collecting effect due to a decrease in the negative pressure.
[0017]
The impermeable wall is provided on the outer periphery of the support plate and a pair of support plates which are arranged facing each other at a predetermined interval in a vertical direction, and expands and contracts by injecting and discharging a fluid such as gas or liquid. A packer is provided, and a lower end of the pair of support plates can penetrate and support a pumping pipe connected to the pump.
[0018]
The shield wall is provided with a vacuum pipe extending downward through the pair of support plates, and is used to increase the diameter of the packer and close the casing on the deeper side to pump water. Accordingly, suction or pressure can be performed via the vacuum pipe.
[0019]
The casing can be inserted and installed in an excavation hole formed in the ground with a filter layer interposed on the outer peripheral side.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show one embodiment of the deep well method according to the present invention.
[0021]
In the deep well method shown in FIG. 1, a hollow cylindrical casing 10 is buried in the ground, a pump 10 is installed in the casing 10, and groundwater collected in the casing 10 is discharged from the pump 10. The basic configuration is to pump water to the ground side by operation.
[0022]
The casing 10 is formed in a cylindrical shape having a closed lower end, and is installed in a borehole 14 excavated by an auger or the like. Between the casing 10 and the inner surface of the excavation hole 14, a filter layer 16 filled with pea gravel or crushed stone is formed.
[0023]
In addition, a strainer section 18 is provided on the lower end side of the casing 10. The strainer portion 18 is provided to take in groundwater into the inside of the casing 10. For example, by arranging elongated rectangular slits in a staggered manner, forming a through hole, and covering the outer periphery with a screen. The filter layer 16 is designed to prevent crushed stones from entering.
[0024]
The pump 12 is a so-called submersible pump, and the lower end of a pumping pipe 20 is connected to the upper end thereof. The pumping pipe 20 extends through the casing 10 to the ground side. The air vent valve 22 is installed on the ground portion.
[0025]
In the case of the present embodiment, the water pump 12 is vertically movably disposed in the casing 10 and is supported by a cylindrical shielding wall 24 capable of expanding and contracting in diameter. The details of this support structure are shown in FIG.
[0026]
The shielding wall 24 shown in the figure has a pair of support plates 24a and a packer 24b. The support plate 24a is a circular plate having a diameter smaller than the inner diameter of the casing 10, and a pair of the support plates 24a are opposed to each other at predetermined intervals in the vertical direction.
[0027]
The packer 24b is formed in a hollow cylindrical shape having a predetermined thickness and length L from an elastic material such as rubber, and one end of an air supply pipe 24c is connected to the packer 24b. A ring-shaped mounting flange 24d is fixedly provided on the inner peripheral surface of the packer 24b in the vertical direction.
[0028]
Each mounting flange 24d is fixed to the outer peripheral edge of the support plate 24a by a bolt nut or the like so that the packer 24b is positioned on the outer periphery of the support plate 24a.
[0029]
The other end of the air supply pipe 24c extends to the ground so as to penetrate through the upper support plate 24a and pass through the casing 10, and extends through the switching valve 26 to the vacuum pump 28 and the compressor. 30.
[0030]
The pumping pump 12 is disposed so as to protrude downward from the lower end of the shielding wall 24, and the pumping pipe 20 is disposed so as to penetrate the center of the pair of support plates 24a. The outer peripheral surface of 20 is fixed to the support plate 24a by welding, whereby the water pump 12 is supported by the impermeable wall 24 so as to move integrally with the impermeable wall 24.
[0031]
In the above configuration, when the switching valve 26 is operated to send gas from the compressor 30 to the air supply pipe 24c, the gas is injected into the packer 24b, and the diameter of the packer 24b increases.
[0032]
When the diameter of the packer 24b is increased, the outer peripheral surface of the packer 24b comes into close contact with the inner peripheral surface of the casing 10, and the casing 10 deeper than the place where the packer 24b is provided is hermetically closed.
[0033]
From this state, when the switching valve 26 is operated to connect the air supply pipe 24c to the vacuum pump 28 side and discharge the gas injected from the packer 24b, the packer 24b contracts.
[0034]
When the packer 24b contracts, its outer peripheral surface is separated from the inner peripheral surface of the casing 10, and the hermetically closed state is released, so that the shielding wall 24 can move up and down in the casing 10 along its longitudinal axis direction. Become.
[0035]
The vertical movement of the shielding wall 24 can be performed, for example, by using the pumping pipe 20, or another means, such as mounting a rod for vertical movement on the support plate 24 a of the water shielding wall 24. Then, it may be moved up and down, or may be suspended and moved by a winch or the like. In this embodiment, the fluid to be injected for expanding and contracting the packer 24b is compressed air. However, the fluid is not limited to this, and may be, for example, a liquid such as water.
[0036]
The member indicated by reference numeral 32 in FIGS. 1 to 3 is a vacuum pipe whose lower end is extended to the vicinity of the water pump 12, and the vacuum pipe 32 penetrates the pair of support plates 24 a. The lower end is open to the vicinity of the pump 12, and the upper end is switchably connected to the vacuum pump 28 and the compressor 30 via a switching valve 34.
[0037]
The vacuum pipe 32 is used when it is necessary to assist the water collecting capacity. When the vacuum pipe 32 is connected to the vacuum pump 28 and suctioned, a negative pressure region is formed near the water pump 12. , Can assist the water collecting ability.
[0038]
In addition, when the compressor 30 is connected to the vacuum pipe 32 and compressed air is blown out from the distal end side, the compressed air can be used for cleaning, for example, when the strainer section 18 is clogged.
[0039]
First, as shown in FIG. 1, the shielding wall 24 configured as described above is placed at a position where the groundwater level WL1 in the ground is substantially in the middle of the length L of the packing 24 b of the shielding wall 24. With the diameter increased, the pump 10 is operated to pump water in a state where the inside of the casing 10 on the deeper side is hermetically closed.
[0040]
In the installation state of the shielding wall 24 shown in FIG. 1, the upper end of the strainer portion 18 of the casing 10 and the lower end of the shielding wall 24 are positioned so as to substantially coincide with each other. To do so, the depth of the groundwater level WL1 is checked in advance, and the length L of the shielding wall 24 may be designed in consideration of the length of the strainer portion 18 of the casing 10 and the groundwater level WL1. In the case of the present embodiment, the length L of the shielding wall 24 is set to be slightly longer than １ ／ of the length of the strainer portion 18.
[0041]
When set so as to be in the state shown in FIG. 1, it is not necessary to provide the strainer portion 18 at an extra place, and more efficient water pumping is possible while effectively utilizing the entire length L of the shielding wall 24. .
[0042]
According to the above-described pumping method, when the groundwater in the casing 10 is pumped, a negative pressure is generated in a portion closed by the shielding wall 24, and the negative pressure causes the surrounding ground to pass through the strainer unit 18, Water can be forcibly and efficiently collected in the casing 10.
[0043]
On the other hand, when the above pumping is continued, the groundwater level WL1 is gradually lowered by the pumping. When the lowered underground water level reaches the lower end of the impermeable wall 24 or less, a gap is formed between the underground water level and the impermeable wall 24, and air enters the casing 10 closed by the impermeable wall 24 from the gap. Flows in.
[0044]
When such inflow of air occurs, the negative pressure in the closed portion decreases, and efficient water collection is hindered. Therefore, in this embodiment, in such a state, the pumping is interrupted and the following operation is performed.
[0045]
That is, the operation of the water pump 12 is stopped, and then the packer 24b of the shielding wall 24 is contracted and moved downward along the casing 10, and thereafter, the packer 24b of the shielding wall 24 is re-expanded. The diameter is created to create a new hermetically closed area, after which the water pump 12 is activated to pump water.
[0046]
FIG. 2 shows a state after performing such an operation. By performing the above operation, it is possible to avoid a decrease in the water collecting effect due to a decrease in the negative pressure due to a decrease in the groundwater level.
[0047]
When performing the above-described operation associated with a decrease in the groundwater level, for example, the load state of the water pump 12 is detected, or a change in the groundwater level is constantly measured by a liquid level meter or the like, and the measurement is performed quantitatively. It is desirable to do.
[0048]
According to the deep well method constructed as described above, the water pump 12 is disposed in the casing 10 so as to be movable up and down, and is supported by the cylindrical shielding wall 24 capable of expanding and contracting. And the inside of the casing 10 on the deeper side is closed to pump water.
[0049]
According to such a pumping method, when the groundwater in the casing 10 is pumped, a negative pressure is generated in a portion closed by the shielding wall 24, and the negative pressure causes the casing from the surrounding ground to pass through the strainer portion 18. Water can be forcibly and efficiently collected in the inside of the fuel cell 10.
[0050]
Therefore, even if the hydraulic conductivity of the ground is smaller than the initial plan and the water collection into the casing 10 is insufficient, the water can be collected from a wide range by the negative pressure, so that a new drilling (additional drilling) is performed. This eliminates the necessity, and eliminates the necessity of adopting a special measure, for example, another method such as a vacuum well method using a large-sized vacuum pump.
[0051]
In the above embodiment, the case where a new deep well is constructed is illustrated. However, the present invention is not limited to this. For example, the shielding wall 24 may be provided inside an existing well using the existing well. It can be installed to improve the pumping efficiency, and if existing wells are used, the effect of improving the construction period and construction cost will be even greater.
[0052]
【The invention's effect】
As described above in detail, according to the deep well method of the present invention, when the hydraulic conductivity of the ground is smaller than an assumed value and sufficient water collection cannot be performed, it is possible to easily cope with the problem. -A large reduction in construction cost can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view of an initial state showing one embodiment of a deep well method according to the present invention.
FIG. 2 is an explanatory cross-sectional view of a process performed when pumping proceeds from the state shown in FIG. 1 and the groundwater level drops.
FIG. 3 is a detailed view of a shielding wall used in the deep well method according to the present invention.
FIG. 4 is an explanatory view of a construction state of a conventional deep well method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Casing 12 Pumping pump 14 Drilling hole 16 Filter layer 18 Strainer part 20 Pumping pipe 24 Shielding wall 24a Support plate 24b Packer

Claims (4)

A hollow cylindrical casing provided with a strainer section for taking in groundwater on the lower side is buried in the ground, a pump is installed in the casing, and groundwater collected in the casing is removed by the pump. In the deep well method of pumping water to the ground side by the operation of
The water pump is vertically movably arranged in the casing, and is supported by a cylindrical shielding wall capable of expanding and contracting in diameter.
Expanding the shielding wall, closing the inside of the casing on the deeper side to pump water,
When the groundwater level is lowered by the pumping and the groundwater level falls below the shielding wall, the pumping is interrupted,
A deep well method, wherein the shielding wall is contracted, moved downward along the casing, and thereafter, the shielding wall is re-expanded to pump water. The impermeable wall is provided on the outer periphery of the support plate and a pair of support plates which are arranged facing each other at a predetermined interval in a vertical direction, and expands and contracts by injecting and discharging a fluid such as gas or liquid. With a packer,
The deep well method according to claim 1, wherein a lower end of the pair of support plates is supported through a pumping pipe connected to the pump. The shielding wall is provided with a vacuum tube extending downward through the pair of support plates,
The pump according to claim 2, wherein, when the diameter of the packer is expanded and the inside of the casing at a deeper side is closed and water is pumped, suction or pressure is performed through the vacuum pipe as necessary. Deep well method. 2. The deep well method according to claim 1, wherein the casing is inserted and installed in an excavation hole formed in the ground with a filter layer interposed on an outer peripheral side. 3.

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