JP2019035688A - Flow velocity and flow direction meter and screen - Google Patents

Abstract

To downsize a flow velocity and flow direction meter.SOLUTION: A flow velocity and flow direction meter 1 comprises a pair of packers 62, 72, a measurement space formed between the pair of packers 62, 72, a plurality of electrodes p1-p12 arranged in the measurement space, and a water permeable body 81 arranged in the measurement space. The respective packers 62, 72 are also formed of a material having water permeability. Especially, the water permeable body 81 arranged in the measurement space is formed of a material having higher water permeability compared to the material forming the respective packers 62, 72. Consequently, there is no need to prepare an air packer, and thus the flow velocity and flow direction meter 1 can be downsized.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flow velocity meter that measures the flow velocity and flow direction of groundwater, and a screen into which the flow velocity meter is inserted.

Conventionally, a measurement method using a specific resistance measurement method is known as a method for measuring the flow (flow velocity and flow direction) of groundwater (see Patent Document 1).
In the measurement method using the specific resistance measurement method, a tracer (distilled water or the like) having a specific resistance different from that of groundwater is arranged in the measurement region. In addition, a change in specific resistance caused by movement of the tracer is detected using a plurality of electrodes arranged in the measurement region. Then, based on the detected change in specific resistance, the flow velocity and flow direction of groundwater are calculated.

Next, the equipment used for the measurement method by the conventional specific resistance measurement method will be described.
FIG. 10 is a diagram showing a configuration of a conventional flow velocity direction meter. FIG. 11 is a cross-sectional view illustrating a configuration of a measurement unit of a conventional flow velocity direction meter.
10 and 11 show a state in which the casing pipe P1 is disposed in the boring hole h, and the flow velocity meter 100 is disposed in the casing pipe P1.
First, the structure of the casing pipe P1 used for the measuring method by the conventional specific resistance measuring method is demonstrated.
As shown in FIG. 10, the casing pipe P1 is formed in a cylindrical shape having a bottom surface and an open top surface. Moreover, the casing pipe P1 has the screen part 200 which can let groundwater pass (inflow and outflow).
The screen part 200 is formed in a cylindrical shape, and a plurality of slits are formed over the entire circumference. Specifically, a cylindrical wedge wire screen or the like is used as the screen unit 200.

Next, the structure of the flow velocity direction meter 100 used in the measurement method by the conventional specific resistance measurement method will be described.
As shown in FIG. 10, a flow velocity meter 100 includes a probe unit 110 inserted into the casing pipe P1, a fixed orientation rod 120 connected to the upper end of the probe unit 110, and a controller (not shown) set on the ground. Z)).
The probe unit 110 includes a pair of air packers 111a and 111b, and a measuring instrument main body 112 disposed between the pair of air packers 111a and 111b.
Each air packer 111a, 111b is formed in a bag shape by an elastic body such as rubber. And each air packer 111a, 111b can be expanded by injecting gas into the inside. Specifically, a tube (not shown) for pumping gas from a cylinder installed on the ground is connected to each of the air packers 111a and 111b. And each air packer 111a, 111b can be expanded by pumping gas from a cylinder through a tube.
The measuring device main body 112 is provided with a measuring unit 113 that allows groundwater to pass (inflow and outflow). The outer periphery of the measuring unit 113 is covered with a stainless mesh m and is formed in a cylindrical shape. As shown in FIG. 11, the measurement unit 113 includes a center electrode c and a plurality of peripheral electrodes p. The plurality of peripheral electrodes p are arranged around the center electrode c. Further, the inside of the measurement unit 113 (inside the stainless mesh m) is filled with glass beads f1.
The center electrode c is formed in a tubular shape extending along the vertical direction. A tube (not shown) for pumping tracer (distilled water) from a tracer tank installed on the ground is connected to the upstream side of the center electrode c via a piston (not shown). The center electrode c is provided with a piston mechanism (not shown) for replacing the tracer pumped from the tracer tank and a plurality of discharge holes through which the replaced tracer is discharged. The discharge hole is disposed in the measurement unit 113.

Next, the procedure at the time of measuring the flow of groundwater using the casing pipe P1 and the flow velocity direction meter 100 will be described.
When measuring the flow of groundwater, first, a boring hole h (bare hole) is excavated in the ground G. At this time, the borehole h is excavated to a position deeper than a region (hereinafter referred to as “target region”) that is a target for measuring the flow of groundwater in the ground G.
Next, the casing pipe P1 is installed in the boring hole h. At this time, the screen unit 200 is disposed at the same depth as the target region. In addition, a hole filling material f2 such as silica sand is filled between the hole wall (inner circumferential surface) of the boring hole h and the outer circumferential surface of the casing pipe P1 in the target region. Further, the gap between the hole wall other than the target region and the casing pipe P1 is closed by bentonite (cohesive soil) f4.
Next, the probe part 110 is installed in the casing pipe P1. At this time, the probe unit 110 is arranged in a state in which a predetermined orientation (a specific peripheral electrode p (first electrode) among the plurality of peripheral electrodes p is in the magnetic north direction) is maintained by the fixed orientation rod 120. Further, the measurement unit 113 is arranged at the same depth as the target region.
Next, after the lower air packer 111b is expanded, a gap filler f3 such as silica sand is filled between the inner peripheral surface of the casing pipe P1 and the outer peripheral surface of the measuring unit 113, and then the upper air packer 111b is expanded. The packer 111a is inflated.
Thus, the installation of the flow velocity meter 100 is completed. Then, after the installation of the flow velocity meter 100 is completed, the measurement of the flow of groundwater in the target area is started after a lapse of half a day (next morning). Here, after the installation of the flow velocity meter 100 is completed, the reason for waiting for the passage of half a day (next morning) is the stability of the flow of groundwater in the target area (pore water pressure) and the tracer built in the flow velocity meter 100 is groundwater. This is to wait for the temperature to be the same (preventing density flow due to temperature difference).

JP 2007-57473 A

However, it is difficult to reduce the size of the conventional flow velocity meter 100.
That is, in the flow velocity direction meter 100, since it is necessary to provide the two air packers 111a and 111b in the probe unit 110, it is difficult to reduce the size of the probe unit 110.
Further, in the flow velocity direction meter 100, the measuring device main body 112 needs to be provided with a piston for pumping a tracer (distilled water) into the center electrode c. Therefore, it is difficult to reduce the size of the measuring device main body 112.
Furthermore, in the flow velocity meter 100, two tubes for pumping gas from the above-mentioned cylinders to the air packers 111a and 111b, one tube for pumping tracer (distilled water) from the tracer tank to the piston, Since two tubes for replacing the tracer with the center of the measurement unit 113 are required, it is difficult to reduce the number of tubes arranged between the ground and the probe unit 110.
In particular, since it is difficult to reduce the size of the probe unit 110 (measuring instrument main body 112), it is difficult to reduce the diameter of the boring hole h.
An object of the present invention is to provide a flow velocity meter that can be miniaturized and a screen that is suitable for the flow velocity meter.

To achieve the above object, a flow velocity meter according to the first invention includes a pair of packers, a measurement region formed between a pair of packers, a plurality of electrodes arranged in the measurement region, A water permeable body arranged in a measurement region and a tracer tube that also serves as a central electrode part, the packer is formed of a material having water permeability, and the water permeable body is compared with a material that forms the packer, It is formed of a material having high water permeability.
In the flow velocity flowmeter according to the first invention, the pair of packers are each formed of a flexible material having water permeability such as an open cell (sponge). Accordingly, the air flow packer can be brought into close contact with the screen and the casing pipe without providing an air packer, and the flow velocity flow direction meter can be downsized.
In particular, in the flow velocity flowmeter according to the first invention, a flexible water permeable body such as a nonwoven fabric or an open cell (sponge) is disposed in the measurement region. Thereby, groundwater can be induced / rectified by the permeable body. Therefore, it is not necessary to fill the glass beads in the measurement region, and it is possible to reduce the trouble of filling and replacing the glass beads. Further, at the time of measurement, in the measurement area, the flexible water-permeable body comes into close contact with the screen, so that it is not necessary to fill the silica sand, and it is possible to prevent the sand accumulation at the bottom of the casing pipe P1. .
Furthermore, in the flow velocity direction meter according to the first invention, the water permeable body is formed of a material having high water permeability as compared with the material forming the packer. Thereby, the outflow to the packer side of the groundwater which flowed into the permeable body is suppressed. Therefore, generation | occurrence | production of the upward flow or downward flow of groundwater in measurement space can be suppressed, and it becomes possible to improve measurement accuracy.
Here, the flow velocity direction meter 1 described later corresponds to the flow velocity direction meter. The pair of packers corresponds to an upper packer 62 and a lower packer 72 described later. A measurement space (measurement unit 80) described later corresponds to the measurement region. The plurality of electrodes correspond to the center electrode c and the peripheral electrodes p1 to p12 described later. The water-permeable body 81 described later corresponds to the water-permeable body.

A flow velocity flow meter according to a second invention is the flow velocity flow meter according to the first invention, wherein the water permeable body is formed of a nonwoven fabric or an open cell body.
According to the flow velocity flow meter according to the second invention, the flow of groundwater in the measurement region can be stabilized.

A screen according to a third invention is a screen formed with a predetermined aperture ratio, which is a combination of a plurality of vertical wires and at least one horizontal wire, and at the connecting portion between the vertical wires and the horizontal wires. The vertical wire is embedded inside the thickness direction of the horizontal wire.
In the screen which concerns on 3rd invention, the vertical wire is embed | buried inside the thickness direction of a horizontal wire in the connection part of a vertical wire and a horizontal wire. Thereby, when the above-mentioned permeable body is arranged in the screen, it is possible to suppress the generation of the upward flow or the downward flow in the measurement region.
That is, when the vertical wire protrudes toward the axial center side with respect to the horizontal wire at the connecting portion between the vertical wire and the horizontal wire, when the permeable body is disposed in the screen, On each side of the protruding vertical wire, a gap is likely to be generated between the permeable body and an upward flow or a downward flow along the vertical wire may be generated through the clearance.
On the other hand, in the screen according to the third aspect of the invention, the vertical wire does not protrude toward the axial center side with respect to the horizontal wire at the connecting portion between the vertical wire and the horizontal wire. When is arranged, the inner peripheral surface of the horizontal wire can be brought into contact with the outer peripheral surface of the permeable body over the entire circumference of the horizontal wire. Therefore, generation | occurrence | production of the clearance gap (gap extended along a perpendicular direction) between the internal peripheral surface of a screen and the outer peripheral surface of a permeable body can be suppressed, and generation | occurrence | production of the upflow or downflow in a measurement area | region can be suppressed. Is possible.
Here, the screen unit 5 described later corresponds to the screen. As the vertical wire, the vertical wire x described later corresponds. As a horizontal wire, the horizontal wire y mentioned later corresponds.

A screen according to a fourth aspect of the invention is the screen according to the third aspect of the invention, characterized in that the horizontal wire is wound spirally.
With the screen according to the fourth aspect of the invention, it is possible to further suppress the occurrence of upward flow or downward flow in the measurement region.

A flow velocity flowmeter according to a fifth invention is a pair of packers, a measurement region formed between the pair of packers, a plurality of electrodes arranged in the measurement region, a tracer tank in which a tracer is accommodated, A tracer pipe connected to the tracer tank, the tracer pipe having an opening and a discharge port provided on the downstream side of the opening, and the opening is in the measurement region. The discharge port is provided such that the tracer can be discharged to a region below the lower packer of the pair of packers.
In the flow velocity flowmeter according to the fifth aspect of the invention, the tracer pipe has an opening and an outlet provided on the downstream side of the opening. In particular, the opening is provided in the measurement area, and the discharge port is provided so that the tracer can be discharged to an area below the lower packer. Accordingly, the tracer can be disposed (replaced) inside the opening by pumping the tracer into the tracer tube and discharging the tracer from the discharge port. And the tracer arrange | positioned inside an opening part can be moved to the outer side of an opening part with the groundwater which flows through a measurement area | region. Therefore, it is not necessary to install a piston for replacing the ground water in the center electrode c with the tracer T, and the flow velocity flow meter can be miniaturized.
Here, the flow velocity direction meter 1 described later corresponds to the flow velocity direction meter. The pair of packers corresponds to an upper packer 62 and a lower packer 72 described later. A measurement space (measurement unit 80) described later corresponds to the measurement region. The plurality of electrodes correspond to the center electrode c and the peripheral electrodes p1 to p12 described later. As the tracer, distilled water T described later is applicable. A distilled water tank 52 described later corresponds to the tracer tank. A center electrode c described later corresponds to the tracer tube. An opening 64 described later corresponds to the opening. A discharge port e described later corresponds to the discharge port.

A flow velocity current meter according to a sixth invention is the flow velocity current meter according to the fifth invention, comprising a center electrode arranged at the center of a plurality of electrodes, wherein the tracer tube is the center electrode. And
According to the flow velocity direction meter according to the sixth invention, the flow velocity direction meter can be further reduced in size.

  According to the present invention, the flow velocity direction meter can be reduced in size, and accordingly, the hole diameter of the boring hole h can be reduced.

It is a figure which shows the structure of the flow velocity flow direction meter which concerns on embodiment of this invention. It is a figure which shows the structure of a sensor unit. It is an enlarged view which shows a measurement part. It is sectional drawing which follows the horizontal surface of a measurement part. It is a figure which shows the structure of a distilled water substitution mechanism. It is a figure which shows the structure of a board | substrate unit. It is sectional drawing which follows the vertical plane of a screen part. It is a fragmentary sectional view of a screen part. It is explanatory drawing of the principle which measures the flow velocity and flow direction of groundwater. It is a figure which shows the structure of the conventional flow velocity direction meter. It is sectional drawing which shows the structure of the measurement part of the conventional flow velocity flow direction meter.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of flow velocity direction meter 1)
First, a flow velocity direction meter 1 according to an embodiment of the present invention will be described.
FIG. 1 is a diagram showing the configuration of a flow velocity direction meter according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of the sensor unit. FIG. 3 is an enlarged view showing the measurement unit. FIG. 4 is a cross-sectional view taken along the horizontal plane of the measurement unit. FIG. 5 is a diagram showing the configuration of the distilled water replacement mechanism. FIG. 6 is a diagram illustrating a configuration of the substrate unit.
As shown in FIG. 1, the flow velocity direction meter 1 includes a measuring instrument body 10 inserted into the casing pipe P2, an insertion rod 20 connected to the measuring instrument body 10, and a controller (not shown) set on the ground. Z)).
The measuring instrument main body 10 includes a sensor unit 11 and a substrate unit 12.
As shown in FIG. 2, the sensor unit 11 includes a sensor unit 30, a distilled water control unit 40, and a distilled water tank storage unit 50.
The sensor unit 30 includes a fixed base unit 60, a removable base unit 70 that can be attached to and detached from the fixed base unit 60, and a measuring unit 80 that is formed between the fixed base unit 60 and the removable base unit 70. , Including.

The fixed base portion 60 includes a frame body 61, a center electrode c, a plurality (12 in this embodiment) of peripheral electrodes p1 to p12, an upper packer 62, and a thermometer 63. Yes.
The frame 61 is formed in a substantially cylindrical shape by an insulating material (insulator). In the present embodiment, the frame body 61 is made of acrylic.
The center electrode c is formed in a cylindrical shape (pipe shape) from an electrically conductive material (electrical conductor). In this embodiment, a stainless steel straight pipe is used as the center electrode c. And in the center electrode c, the inner side becomes a pressure feed path (flow path) of the distilled water T.
The center electrode c extends linearly along the vertical direction. The center electrode c is disposed along the center axis of the frame body 61 (coaxially) inside the frame body 61. The center electrode c protrudes downward from the lower end portion of the frame body 61.
As shown in FIG. 3, a discharge port e through which distilled water T is discharged (released) is provided at the lower end of the center electrode c. Here, the lower end of the center electrode c reaches a position below the lower end of the detachable base part 70. Thereby, in the measuring device main body 10, the distilled water T can be discharged to a position below the detachable base portion 70 (lower packer 72 described later) through the discharge port e.
The center electrode c is provided with an opening 64. The opening 64 is provided on the upstream side with respect to the discharge port e. In particular, the opening 64 is provided so as to be disposed in a measurement space (measurement unit 80) described later. The opening 64 is provided with a plurality of through holes substantially uniformly over the entire circumference. In the present embodiment, the opening 64 is formed in a mesh shape (mesh shape). And in the opening part 64, the outer side and inner side of the center electrode c are mutually connected via each through-hole.
Thereby, in the center electrode c, it is possible to allow groundwater to pass through the opening 64. That is, in the center electrode c, it is possible to allow groundwater to flow inward through the opening 64 (each through hole) and to discharge the groundwater flowing inward to the outside. In particular, the distilled water T arranged inside the opening 64 can be discharged to the outside of the opening 64 by being put on the flow of groundwater passing (inflow and outflow) through the opening 64.

Each of the peripheral electrodes p1 to p12 is formed in a cylindrical shape (needle shape) from an electrically conductive material (electrical conductor). In the present embodiment, stainless steel rods are used as the peripheral electrodes p1 to p12. Each of the peripheral electrodes p1 to p12 extends linearly along the vertical direction. The peripheral electrodes p <b> 1 to p <b> 12 are arranged along the inner peripheral surface of the frame body 61 inside the frame body 61. The peripheral electrodes p <b> 1 to p <b> 12 protrude downward from the lower end portion of the frame body 61. The lower ends of the peripheral electrodes p1 to p12 are arranged in the measurement space (measurement unit 80).
Specifically, as shown in FIG. 4, the twelve peripheral electrodes p <b> 1 to p <b> 12 are arranged on one circumference centered on the central electrode c at a viewpoint along the vertical direction. That is, the distances (intervals) between the peripheral electrodes p1 to p12 and the center electrode c are the same for all the peripheral electrodes p1 to p12. Further, the twelve peripheral electrodes p1 to p12 are arranged at equiangular intervals (30 ° intervals in the present embodiment).
Here, all the electrodes c and p1 to p12 are insulated from each other by the frame body 61.

The upper packer 62 is formed of a material having water permeability. Specifically, the upper packer 62 is formed of an open cell body having elasticity. In particular, the upper packer 62 is made of a material that is harder and has a larger elastic coefficient than a material that forms the water-permeable body 81 described later. In the present embodiment, the upper packer 62 is formed of a hard foam material (sponge) having an open cell structure (open cell structure).
The upper packer 62 is formed in a cylindrical shape having a predetermined thickness. The upper packer 62 is disposed so as to cover the outer peripheral surface of the frame body 61. The inner peripheral surface of the upper packer 62 is in close contact with the outer peripheral surface of the frame body 61. The position of the lower end of the upper packer 62 substantially coincides with the position of the lower end of the frame body 61. That is, the lower surface (bottom surface) of the upper packer 62 is disposed on substantially the same surface as the lower surface (bottom surface) of the frame body 61.
Here, the outer diameter of the upper packer 62 is larger than the inner diameter of the casing pipe P2. Thereby, when the measuring instrument main body 10 is inserted inside the casing pipe P2, the outer peripheral surface of the upper packer 62 and the inner peripheral surface of the casing pipe P2 can be brought into close contact by the elasticity (shrinkage) of the upper packer 62. it can.
In the present embodiment, one (series) upper packer 62 is arranged on the outer peripheral surface of the frame body 61. However, a plurality of (for example, two) upper packers 62 that are independent from each other may be arranged along the vertical direction on the outer peripheral surface of the frame body 61.

  The thermometer 63 is composed of a thermistor or the like. The thermometer 63 is disposed inside the frame body 61. And the thermometer 63 detects the temperature change of the frame 61 by the temperature of the groundwater which flows through measurement space (measurement part 80) by detecting the temperature of the frame 61 (measurement). The thermometer 63 outputs a detection signal to a control board 91 (specifically, a thermometer amplifier) described later.

The detachable base part 70 includes a frame body 71 and a lower packer 72.
The frame 71 is formed in a substantially cylindrical shape by an insulating material (insulator). In the present embodiment, the frame 71 is made of acrylic. The frame 71 is provided with an electrode insertion hole (not shown) along its central axis. The electrode insertion hole is a through hole.

The lower packer 72 is formed of the same material as the upper packer 62. That is, the lower packer 72 is made of a material having water permeability. In particular, the lower packer 72 is made of a material that is harder and has a larger elastic coefficient than a material that forms the water-permeable body 81 described later. Specifically, the lower packer 72 is formed of an open cell body having elasticity. In the present embodiment, the lower packer 72 is formed of a hard foam material (sponge) having an open cell structure (open cell structure).
The lower packer 72 is formed in a cylindrical shape having a predetermined thickness. The lower packer 72 is disposed so as to cover the outer peripheral surface of the frame 71. The inner peripheral surface of the lower packer 72 is in close contact with the outer peripheral surface of the frame 71. The position of the upper end of the lower packer 72 substantially coincides with the position of the upper end of the frame 71. That is, the upper surface (top surface) of the lower packer 72 is disposed on substantially the same plane as the upper surface (top surface) of the frame 71.
Here, the outer diameter of the lower packer 72 is substantially the same as the outer diameter of the upper packer 72. That is, the outer diameter of the lower packer 72 is larger than the inner diameter of the casing pipe P2. Thereby, when the measuring instrument main body 10 is inserted inside the casing pipe P2, the outer peripheral surface of the lower packer 72 and the inner peripheral surface of the casing pipe P2 are brought into close contact by the elasticity (shrinkage) of the lower packer 72. be able to.
In the present embodiment, one (series) lower packer 72 is arranged on the outer peripheral surface of the frame 71. However, a plurality of (for example, two) lower packers 72 that are independent of each other may be arranged on the outer peripheral surface of the frame 71 along the vertical direction.

The detachable base part 70 is attached to the fixed base part 60 with the center electrode c inserted through the electrode insertion hole. In a state where the detachable base portion 70 is mounted on the fixed base portion 60, the lower end portion of the center electrode c protrudes downward from the lower end of the detachable base portion 70. Here, a screw groove (not shown) is formed on the outer peripheral surface of the lower end portion of the center electrode c. The detachable base portion 70 is fixed to the fixed base portion 60 by screwing the fixing nut N into the screw groove at the lower end portion of the center electrode c.
Further, when the detachable base portion 70 is mounted on the fixed base portion 60, the lower surface of the frame body 61 (upper packer 62) and the upper surface of the frame body 71 (lower packer 72) are arranged at a predetermined interval. Is done. Thus, a measurement space in which groundwater flows is formed between the lower surface of the frame body 61 (upper packer 62) and the upper surface of the frame body 71 (lower packer 72).
And in the sensor part 30, the measurement part 80 is comprised by arrange | positioning the permeable body 81 mentioned later in measurement space.

A permeable body 81 is disposed in the measurement unit 80 (measurement space). The permeable body 81 is disposed so as to fill substantially the entire measurement space. In the measurement unit 80 (measurement space), the water is guided (centered) and rectified by the permeable body 81.
The water permeable body 81 is formed of a material having water permeability. In particular, the water permeable body 81 is formed of a material having a high water permeability (a high water permeability coefficient) as compared with the material forming each of the packers 62 and 72. Specifically, the water permeable body 81 is formed of an open cell body having elasticity. In this embodiment, the water permeable body 81 is formed of a non-woven fabric, a foam material (sponge) having an open cell structure (open cell structure), or the like.
The permeable body 81 is formed in a disk shape. The water permeable body 81 is provided with a through hole along its central axis. The vertical dimension of the permeable body 81 is larger than the vertical dimension of the measurement space (the dimension between the lower surface of the frame body 61 and the lower surface of the frame body 71). As a result, when the permeable body 81 is placed in the measurement space, the upper surface of the permeable body 81 and the lower surface of the frame body 61 (upper packer 62) can be brought into close contact by the elasticity (shrinkage) of the permeable body 81. The lower surface of the water permeable body 81 and the upper surface of the frame body 71 (lower packer 72) can be brought into close contact with each other.
Further, the outer diameter of the water permeable body 81 is substantially the same as the outer diameter of each of the packers 62 and 72. That is, the outer diameter of the water permeable body 81 is larger than the inner diameter of the casing pipe P2 (particularly, the screen portion 5 described later). Thereby, when the measuring instrument main body 10 is inserted inside the casing pipe P2, due to the elasticity (shrinkage) of the permeable body 81, the outer peripheral surface of the permeable body 81 and the inner peripheral surface of the casing pipe P2 (screen portion 5) Can be adhered.
The outer diameter of the water permeable body 81 may be larger than the outer diameter of each of the packers 62 and 72. In particular, the outer diameter of the water permeable body 81 may be larger than the outer diameter of the screen portion 5. Thereby, when the water-permeable body 81 is inserted inside the screen part 5, it becomes possible to make the inner peripheral surface of the horizontal wire y mentioned later and the inner peripheral surface of the water-permeable body 81 adhere more reliably.

The permeable body 81 is disposed in the measurement space in a state where the central electrode c is inserted into the through hole and the peripheral electrodes p1 to p12 are inserted (pierced) therein. Thus, in the measurement unit 80 (measurement space), the central electrode c is arranged at the center at the viewpoint along the vertical direction, and the twelve peripheral electrodes p1 to p12 are one circle centering on the central electrode c. It is arranged on the circumference.
In a state where the detachable base part 70 is mounted on the fixed base part 60, the lower surface of the upper packer 62 and the upper surface of the permeable body 81 are in close contact, and the upper surface of the lower packer 72 and the lower surface of the permeable body 81 are in close contact. . That is, the upper packer 62, the water permeable body 81, and the lower packer 72 are continuously arranged along the vertical direction.
Here, as described above, the water permeable body 81 is formed of a material having a high water permeability (a high water permeability coefficient) as compared with the material forming the packers 62 and 72. That is, the fluid (ground water and distilled water T) flows more easily inside the water permeable body 81 than inside the packers 62 and 72. Thereby, the outflow to the packers 62 and 72 side of the groundwater (or distilled water T) which flowed in into measurement space (permeable body 81) is suppressed. Therefore, it is possible to suppress the occurrence of an upward flow or downward flow of groundwater (or distilled water T) in the measurement space.

Here, when exchanging the permeable body 81, first, the fixing nut N screwed into the thread groove at the lower end of the center electrode c is removed. Further, the detachable base portion 70 inserted through the center electrode c of the fixed base portion 60 is detached from the fixed base portion 60. Then, the water permeable body 81 inserted through the center electrode c of the fixed base portion 60 is detached from the fixed base portion 60.
Thereafter, a new water permeable body 81 is inserted through the center electrode c of the fixed base portion 60. At this time, the center electrode c is inserted through the through hole of the water permeable body 81. On the other hand, each of the peripheral electrodes p <b> 1 to p <b> 12 is inserted into the water permeable body 81 by piercing the water permeable body 81.
Thereafter, the detachable base portion 70 is inserted through the center electrode c of the fixed base portion 60. At this time, the center electrode c is inserted into the electrode insertion hole of the detachable base portion 70. Further, the fixing nut N is screwed into the screw groove at the lower end portion of the center electrode c protruding from the lower end of the detachable base portion 70. Thereby, the replacement of the permeable body 81 is completed.

The distilled water control unit 40 includes a frame body 41, a distilled water pressure feed path 42, an electromagnetic valve 43, and a pressure gauge 44 disposed inside the frame body 41.
The frame body 41 is formed in a substantially cylindrical shape. In the present embodiment, the frame body 41 is made of stainless steel. The upper end portion of the frame body 61 is fitted to the lower end portion of the frame body 41.
As shown in FIG. 5, the distilled water pressure feed path 42 connects a distilled water tank 52 described later and an upper end (opening) of the center electrode c to each other. The distilled water pressure feed path 42 includes an upstream pressure feed path 42a and a downstream pressure feed path 42b. The upstream pressure feed path 42 a connects the distilled water tank 52 and the upstream connection path (connection port) of the electromagnetic valve 43 to each other. The downstream side pressure feed path 42b connects the downstream side connection path (connection port) of the electromagnetic valve 43 and the upper end (opening) of the center electrode c. Each pressure feeding path 42a, 42b is formed of a nylon tube or the like.
The electromagnetic valve 43 is a solenoid valve. A control signal from a control board 91 (specifically, a solenoid valve control circuit) is input to the solenoid valve 43. Then, the solenoid valve 43 causes the upstream connection path and the downstream connection path to communicate with each other in response to the input of the control signal from the solenoid valve control circuit to stop the control signal from the solenoid valve control circuit. Accordingly, the upstream connection path and the downstream connection path are blocked from each other.

  The pressure gauge 44 is disposed in the downstream pressure feed path 42b. The pressure gauge 44 detects the pressure of the groundwater present in the measurement space (measurement unit 80) by detecting (measuring) the pressure of the distilled water T (or groundwater) present in the downstream pressure feed path 42b. The pressure gauge 44 outputs a detection signal to the control board 91 (specifically, a pressure gauge amplifier).

The distilled water tank housing unit 50 includes a frame 51 and a distilled water tank 52 disposed inside the frame 51.
The frame 51 is formed in a substantially cylindrical shape. In the present embodiment, the frame 51 is made of stainless steel. The upper end portion of the frame body 41 is fitted to the lower end portion of the frame body 51.
The distilled water tank 52 is disposed inside the frame body 51. The distilled water tank 52 accommodates a tracer (tracker). Here, the tracer is selected according to the quality of groundwater to be measured. That is, a solution (distilled water, saline solution, etc.) having a specific resistance different from that of the ground water to be measured is selected as the tracer. In this embodiment, distilled water is used as the tracer.
The distilled water tank 52 is connected to the controller via the pressure tube P. That is, the controller is provided with a pressure regulator R that can attach and detach the nitrogen cylinder B. The nitrogen cylinder B contains nitrogen gas. One end of the pressure tube P is connected to the upper end of the distilled water tank 52, and the other end of the pressure tube P is connected to the pressure regulator R. Thus, by operating the valve of the pressure regulator R, the nitrogen gas accommodated in the nitrogen cylinder B can be pumped into the distilled water tank 52 at a pressure corresponding to the operation amount of the valve. Then, in a state where the inside of the distilled water tank 52 is pressurized with nitrogen gas, the electromagnetic valve 43 is opened, so that the distilled water T accommodated in the distilled water tank 52 is brought into the center electrode c at a predetermined pressure. Can be pumped. In the present embodiment, a nylon tube is used as the pressure tube P.

As shown in FIG. 6, the board unit 12 includes a frame body 90, a control board 91 disposed inside the frame body 90, and a rod reducer 92 connected to the upper end portion of the frame body 90. It is configured.
The frame 90 is formed in a substantially cylindrical shape. In the present embodiment, the frame body 90 is made of stainless steel. The upper end of the sensor unit 11 (frame 51) is fitted to the lower end of the frame 90.
Various control circuits (not shown) are arranged on the control board 91. In the present embodiment, a communication circuit, a 12-channel amplifier, a pressure gauge amplifier, a thermometer amplifier, a three-dimensional magnetic direction sensor, an electromagnetic valve control circuit, and the like are arranged on the control board 91.
Further, power is supplied to the control board 91 from a controller (specifically, a battery) via a power line (metal line).

The communication circuit controls mutual communication with the controller. In the present embodiment, the communication circuit is connected (electrically connected) to the controller via two signal lines (metal lines). The communication circuit receives a control command (control signal) from the controller. And in the control board 91, the process according to the content of the control command received by the communication circuit is performed. Further, the communication circuit outputs various information input from a 12-channel amplifier, a pressure gauge amplifier, a thermometer amplifier, a three-dimensional magnetic orientation sensor, and the like to the controller.
The 12-channel amplifier controls the application of voltage between each of the peripheral electrodes p1 to p12 and the center electrode c, which will be described later, and detects the specific resistance of groundwater between each of the peripheral electrodes p1 to p12 and the center electrode c. .
The 12-channel amplifier applies an alternating voltage between the peripheral electrodes p1 to p12 and the center electrode c. The 12-channel amplifier detects (measures) the specific resistance of groundwater between the peripheral electrodes p1 to p12 and the center electrode c. And 12 channel amplifier outputs the information which shows the specific resistance of the detected groundwater with respect to a controller via a communication circuit.

The pressure gauge amplifier calculates the pressure based on the detection signal input from the pressure gauge 44. And the information which shows the calculated pressure is output with respect to a controller via a communication circuit.
The thermometer amplifier calculates the temperature based on the detection signal input from the thermometer 63. Then, information indicating the calculated temperature is output to the controller via the communication circuit.
The three-dimensional magnetic azimuth sensor includes a magnetic sensor (such as a Hall element). In the present embodiment, the three-dimensional azimuth sensor detects geomagnetism by three magnetic sensors arranged toward the X axis, the Y axis, and the Z axis that are orthogonal to each other.
The three-dimensional magnetic azimuth sensor calculates the azimuth (angle relative to magnetic north) in which the peripheral electrodes p1 to p12 around the central electrode c are arranged based on the geomagnetism detected by the three magnetic sensors. In the present embodiment, the three-dimensional magnetic orientation sensor calculates the orientation of the peripheral electrode p1. And the information which shows the azimuth | direction calculated about the peripheral electrode p1 is output with respect to a controller via a communication circuit.
The electromagnetic valve control circuit starts outputting a control signal to the electromagnetic valve 43 in response to an input of a control command designating opening of the valve from the controller (specifically, the valve switch S). Further, the electromagnetic valve control circuit stops the output of the control signal to the electromagnetic valve 43 in response to an input of a control command designating the closing of the valve from the controller (specifically, the valve switch S).

The rod reducer 92 is formed in a substantially cylindrical shape. In the embodiment, the rod reducer 92 is made of stainless steel. The upper end of the frame 90 is fitted to the lower end of the rod reducer 92.
A female composite connector C <b> 1 is disposed on the side surface of the rod reducer 92. In the present embodiment, the measuring instrument main body 10 and the controller are connected to each other via a single composite cable (not shown). The composite cable is configured as a single cable by combining a plurality of cables including the pressure tube P, a power supply line, and two signal lines. A male composite connector is disposed at each end of the composite cable.
The composite cable is wound around the cable drum D. Then, the male composite connector disposed at one end of the composite cable is fitted to the female composite connector C1 disposed at the rod reducer 92, and is disposed at the other end of the composite cable. By fitting the male composite connector to the female composite connector arranged in the controller, the measuring instrument main body 10 and the controller are connected to each other.
Further, the upper end of the rod reducer 92 is provided with a fitting portion F into which the lower end portion of the insertion rod 20 is fitted.

The insertion rod 20 is formed in a rod shape. Here, when the measuring instrument main body 10 is inserted into the casing pipe P <b> 2, a predetermined number of insertion rods 20 are connected to the measuring instrument main body 10 according to the depth at which the measuring instrument main body 10 is arranged.
Each insertion rod 20 is made of aluminum. In particular, an air chamber that is blocked from the outside is provided inside each insertion rod 20. As a result, when the measuring instrument body 10 is inserted into the casing pipe P2 filled with groundwater, buoyancy is generated in each insertion rod 20, thereby providing a force necessary to lower the measuring instrument body 10. It becomes possible to reduce. Similarly, when the measuring instrument main body 10 is extracted from the inside of the casing pipe P2 filled with groundwater, buoyancy is generated in each insertion rod 20 so that the force necessary to raise the measuring instrument main body 10 is increased. It becomes possible to reduce.
One end of each insertion rod 20 is provided with a fitting portion (not shown) that can be fitted to the other end of the other insertion rod 20. Thereby, the plurality of insertion rods 20 can be connected to each other linearly.

The controller includes a communication device, an arithmetic device (not shown), a pressure regulator R, a valve switch S, a battery, and a barometer.
The communication device is calculated by various information input from the control board 91 (communication circuit) (information indicating the specific resistance of groundwater detected by the 12-channel amplifier, information indicating the pressure calculated by the pressure gauge amplifier, and the thermometer amplifier. Information indicating the measured temperature, barometric pressure information calculated by a barometer, water pressure (differential pressure) information calculated from the difference between the pressure calculated by the pressure gauge amplifier and the pressure calculated by the barometer amplifier, three-dimensional magnetic orientation Information indicating the orientation of the peripheral electrode p1 calculated by the sensor is appropriately output to the arithmetic unit.
In the present embodiment, a tablet personal computer (hereinafter referred to as “tablet PC”) including a display (display device) capable of touch operation is used as the arithmetic device. And a communication apparatus transmits the various information input from the control board 91 (communication circuit) with respect to tablet PC by radio | wireless communication (Bluetooth (trademark) etc.).
And tablet PC performs the arithmetic processing according to the input information. Specifically, the tablet PC is calculated by the specific resistance of the groundwater detected for each of the peripheral electrodes p1 to p12, the pressure calculated by the pressure gauge amplifier, the atmospheric pressure calculated by the barometer amplifier, and the thermometer amplifier. Each temperature recorded (recorded) over time.
Further, the change in the specific resistance of the groundwater detected for each of the peripheral electrodes p1 to p12 with time, the water pressure (differential pressure) that is the difference between the pressure calculated by the pressure gauge amplifier and the pressure calculated by the barometer amplifier. Each of the change with time and the change with time of the temperature calculated by the thermometer amplifier are displayed on the display.
In particular, the tablet PC determines the flow velocity and flow direction of groundwater (water flow) based on the change over time of the specific resistance of groundwater detected for each peripheral electrode p1 to p12 and the orientation of each peripheral electrode p1 to p12. calculate. Then, the calculated groundwater flow velocity and direction are displayed on the display.

The pressure regulator R can attach and detach the nitrogen cylinder B. And the pressure regulator R pressure-feeds the nitrogen gas accommodated in the nitrogen cylinder B into the distilled water tank 52 through the pressure tube P by the predetermined pressure by operating a valve.
The valve switch S includes an operation unit (not shown) that can be switched between an open state and a closed state. Then, the valve switch S outputs a control command designating opening of the valve to the control board 91 (electromagnetic valve control circuit) in response to the operation unit being switched to the open state. Further, the valve switch S outputs a control command for designating valve closing to the control board 91 (electromagnetic valve control circuit) in response to the operation unit being switched to the closed state.
The battery supplies power to the controller and also supplies power to the control board 91 via the power line.

(Configuration of casing pipe P2)
Next, the casing pipe P2 according to the embodiment of the present invention will be described.
FIG. 7 is a cross-sectional view taken along the vertical plane of the screen portion. FIG. 8 is a partial cross-sectional view of the screen portion.
FIG. 8A shows a cross section of the screen portion 2 along the horizontal plane. FIG. 8B shows a cross section taken along line AA shown in FIG. FIG. 8C shows a cross section taken along the line BB shown in FIG.
As shown in FIG. 1, the casing pipe P <b> 2 includes an upper pipe 2, a screen pipe 3, and a lower pipe 4. The upper pipe 2, the screen pipe 3, and the lower pipe 4 are connected to each other in a series.
The upper pipe 2 is formed in a cylindrical shape. In the present embodiment, a vinyl chloride pipe is used as the upper pipe 2. A thread groove is formed on the inner peripheral surface of the lower end portion of the upper pipe 2.
The lower pipe 4 is formed in a cylindrical shape having a bottom surface. In the present embodiment, a vinyl chloride pipe is used as the lower pipe 4. A thread groove is formed on the inner peripheral surface of the lower end portion of the lower pipe 4.

The screen pipe 3 is formed in a cylindrical shape. As shown in FIG. 7, the screen pipe 3 is provided with a screen portion 5. The screen unit 5 is a cylindrical screen. In other words, the screen portion 5 is provided with a plurality of through holes substantially uniformly over the entire circumference.
Here, the aperture ratio of the screen portion 5 is set in the range of 25% to 35%, preferably in the range of 27% to 33%. In this embodiment, the aperture ratio of the screen unit 5 is set to 30%.

As shown in FIGS. 7 and 8, the screen unit 5 is configured by combining a plurality of vertical wires x and at least one horizontal wire y. In the present embodiment, the screen unit 5 is configured by combining twelve vertical wires x and three horizontal wires y. That is, the outer peripheral wall of the screen part 5 is formed by combining 12 vertical wires x and 3 horizontal wires y.
Each vertical wire x is formed in a cylindrical shape. As shown in FIG. 7, each vertical wire x extends in a straight line parallel to the central axis of the screen pipe 3 (screen portion 5). The twelve vertical wires x are parallel to each other. As shown in FIG. 8A, at the viewpoint along the central axis of the screen pipe 3, the twelve vertical wires x are equiangularly spaced from each other on one circumference centered on the axis of the screen pipe 3. (In this embodiment, they are arranged at intervals of 30 °).
Each horizontal wire y is formed in a flat plate shape. As shown in FIG. 7, each horizontal wire y is wound spirally around the axis of the screen pipe 3. In the screen portion 5, twelve vertical wires x are connected to each other by the horizontal wires y. That is, each horizontal wire y is spirally wound around the axis of the screen pipe 3 so as to sequentially connect two adjacent vertical wires x out of 12 vertical wires z. Has been. And in the part which each horizontal wire y and each vertical wire x cross | intersect, the said horizontal wire y and the said vertical wire x are mutually connected.

In particular, as shown in FIGS. 8A and 8B, in each connecting portion between the vertical wire x and the horizontal wire y, the vertical wire x is in the thickness direction of the horizontal wire y (the thickness of the outer peripheral wall of the screen pipe 3). Direction). Accordingly, as shown in FIG. 8B, in the screen portion 5, the vertical wire x does not protrude toward the axial center of the screen pipe 3 with respect to the horizontal wire y. In other words, in the screen portion 5, the inner peripheral surface of the horizontal wire y is disposed at a position on the axial center side of the screen pipe 3 with respect to the vertical wire x. Therefore, when the measurement unit 80 (permeable body 81) of the flow velocity direction meter 1 is disposed in the screen unit 5, it is possible to suppress the generation of the upward flow or the downward flow in the measurement unit 80.
That is, when the vertical wire x protrudes toward the axial center of the screen pipe 3 with respect to the horizontal wire y, the measuring unit 80 (permeable body 81) of the flow velocity flow direction meter 1 is in the screen unit 5. When arranged, each side of the vertical wire x projecting with respect to the horizontal wire y tends to generate a gap with the water permeable body 81, and rise along the vertical wire x through the gap. Flow or downflow may occur.
On the other hand, in the screen part 5, since the vertical wire x does not protrude toward the axial center side of the screen pipe 3 with respect to the horizontal wire y, the measuring part 80 (permeable body 81) of the flow velocity direction meter 1 is used. Is disposed in the screen portion 5, the inner circumferential surface of the horizontal wire y and the outer circumferential surface of the water permeable body 81 can be brought into close contact with each other over the entire circumference of the horizontal wire y. Therefore, generation | occurrence | production of the clearance gap (gap extended along a perpendicular direction) between the internal peripheral surface of the screen part 5 and the outer peripheral surface of the permeable body 81 can be suppressed, and generation | occurrence | production of the upward flow or the downward flow in the measurement part 80 is possible. Can be suppressed.
As shown in FIGS. 8B and 8C, each horizontal wire y has a wedge-shaped (tapered) cross section along a vertical plane. That is, the thickness of each horizontal wire y in the vertical direction gradually decreases toward the axial center side of the screen pipe 3.
As a result, the particles adhering to the outside of the screen portion 5 can be easily separated by backwashing.

In the present embodiment, the screen pipe 3 is formed of a resin such as a peak (Poly Ether Ether Ketone) or acrylic. The screen pipe 3 is formed by a 3D printer.
On the outer peripheral surface of the upper end portion of the screen pipe 3, a screw thread that is screwed into a screw groove formed on the inner peripheral surface of the lower end portion of the upper pipe 2 is formed. Further, on the outer peripheral surface of the lower end portion of the screen pipe 3, a screw thread that is screwed into a screw groove formed on the inner peripheral surface of the upper end portion of the lower pipe 4 is formed.
The upper pipe 2, the screen pipe 3, and the lower pipe 4 have the same inner diameter and outer diameter.
Then, the thread formed on the outer peripheral surface of the upper end portion of the screen pipe 3 is screwed into the screw groove formed on the inner peripheral surface of the lower end portion of the upper pipe 2, and the upper end portion of the lower pipe 4. A casing pipe P <b> 2 is configured by screwing a thread formed on the outer peripheral surface of the lower end portion of the screen pipe 3 into a thread groove formed on the inner peripheral surface.

(Procedure for measuring the flow of groundwater using the flow velocity meter 1)
Next, the procedure at the time of measuring the flow of groundwater using the flow velocity direction meter 1 will be described.
As shown in FIG. 1, in order to measure the flow of groundwater using the flow velocity direction meter 1, first, a boring hole h (bare hole) is excavated in the ground G. At this time, the boring hole h is excavated to a position deeper than a region (hereinafter referred to as “target region”) that is a target for measuring the flow of groundwater in the ground G.
Next, the casing pipe P2 is installed in the boring hole h. At this time, the screen unit 5 is disposed at the same depth as the target region.
Next, in a hole deeper than the lower end of the screen portion 5 in the borehole h, between the hole wall (inner peripheral face) of the borehole h and the outer peripheral face of the casing pipe P2, the inside of the hole such as bentonite (viscous soil) Filling material f4 is filled.
Next, in-hole fillers such as silica sand between the hole wall (inner peripheral surface) of the borehole h and the outer peripheral surface of the screen portion 3 at a depth from the upper end to the lower end of the screen portion 5 in the borehole h. Fill with f2.
Next, at a depth shallower than the upper end of the screen portion 5 in the borehole h, between the hole wall (inner peripheral surface) of the borehole h and the outer peripheral surface of the casing pipe P2 Filling material f4 is filled.
Next, the measuring device main body 10 is installed in the casing pipe P2. At this time, the measuring unit 80 is arranged at the same depth as the target region by connecting the plurality of insertion rods 20 to each other. Thereby, the installation of the measuring instrument main body 10 is completed.
Next, after opening the valve of the pressure regulator R to pressurize the distilled water tank 52, the valve switch S is switched to the open state, and a predetermined amount of distilled water T is discharged from the outlet e of the center electrode c. To release from. As a result, the air in the center electrode c and the distilled water pressure feed path 42 is discharged, and the pressure can be detected by the pressure gauge 44.

After that, the changes over time of the pressure calculated by the pressure gauge amplifier displayed on the display of the tablet PC and the changes over time of the temperature calculated by the thermometer amplifier are monitored to stabilize the pressure and temperature of the groundwater. Wait to do. And after confirming that the pressure and temperature of groundwater were stabilized, measurement of the flow of groundwater is started. The reason for waiting for the pressure and temperature of the groundwater to stabilize is to wait for the flow of groundwater in the target region to be stable (the pore water pressure and the water temperature are stable).
When starting measurement of the flow of groundwater, first, the valve switch S is switched to the open state, and a predetermined amount of distilled water T is discharged from the outlet e of the center electrode c. Thereby, the ground water in the center electrode c is replaced with distilled water T, and the distilled water T is disposed in the opening 64.
Next, the change with time of the specific resistance of the groundwater detected for each of the peripheral electrodes p1 to p12 after the distilled water T is disposed in the opening 64 is stored. Then, based on the change over time in the specific resistance of the groundwater detected for each of the peripheral electrodes p1 to p12 and the orientation of the peripheral electrode p1 detected by the three-dimensional magnetic orientation sensor, the flow velocity and flow direction of the groundwater (water flow) are Calculated.

(Principle of measuring the velocity and direction of groundwater)
Next, the principle of measuring the velocity and direction of groundwater will be described.
FIG. 9 is an explanatory diagram of the principle of measuring the flow rate and flow direction of groundwater.
FIG. 9A shows the distribution of distilled water T that changes over time. That is, in FIG. 9A, “a” indicates the initial state, “b” indicates the first state after t1 time has elapsed from the initial state, and “c” has elapsed t2 time from the initial state. “D” indicates a third state after t3 time has elapsed from the initial state, and “e” indicates a fourth state after t4 time has elapsed from the initial state (t1 <t2 <T3 <t4).
FIG. 9B shows the passage of time between each of the peripheral electrodes p1 to p12 and the central electrode c arranged in parallel to the flow of groundwater (in this example, the peripheral electrode p7 and the central electrode c) It shows the relationship with the resistivity of groundwater.
In the flow velocity direction meter 1, the flow of groundwater is measured by a specific resistance measurement method. That is, in the flow velocity meter 1, when measuring the flow of groundwater, first, distilled water T is disposed in the opening 64 of the center electrode c (initial state “a”). And when distilled water T is arrange | positioned in the opening part 64, distilled water T will move with the flow of groundwater with progress of time, and the specific resistance in measurement space (measurement part 80) will change. And the process of the change of the specific resistance in measurement space (measurement part 80) is detected by 12 peripheral electrodes p1-p12, and the flow velocity and flow direction of groundwater are calculated based on a detection result.

Specifically, as shown in FIG. 9A, in the initial state “a”, distilled water T does not flow out of the opening 64. Thus, the specific resistance value between the peripheral electrode p7 and the center electrode c indicates the specific resistance value of groundwater. Therefore, as shown in FIG. 9B, in the initial state “a”, the specific resistance value between the peripheral electrode p7 and the center electrode c becomes the specific resistance (initial value) of the groundwater.
On the other hand, as shown in FIG. 9A, in the first state “b” to the third state “d”, as time passes, distilled water T rides on the flow of groundwater and moves toward the peripheral electrode p7. Move. Accordingly, the specific resistance value between the peripheral electrode p7 and the central electrode c indicates the specific resistance value of a solution in which ground water and distilled water T are mixed. Therefore, as shown in FIG. 9B, the specific resistance value between the peripheral electrode p7 and the center electrode c changes with time as in the first state “b” to the third state “d”.
On the other hand, as shown in FIG. 9A, in the fourth state “e”, the distilled water T moves to the outside of the peripheral electrode p7 (on the opposite side to the center electrode c). Thereby, again, the specific resistance value between the peripheral electrode p7 and the center electrode c shows the specific resistance value of groundwater. Therefore, as shown in FIG. 9B, in the fourth state “e”, the specific resistance value between the peripheral electrode p7 and the center electrode c becomes the specific resistance (initial value) of the groundwater again.
In the flow velocity direction meter 1, twelve peripheral electrodes p1 to p12 are arranged at an angular interval of 30 °. As a result, when measuring the flow of groundwater, specific resistance data can be obtained for each of the 12 peripheral electrodes p1 to p12. And in the flow velocity direction meter 1, the flow velocity and flow direction of groundwater are calculated based on the data of the specific resistance concerning the 12 peripheral electrodes p1 to p12.

(Operation and effect of flow velocity direction meter 1 and casing pipe P2)
Next, functions and effects of the flow velocity direction meter 1 and the casing pipe P2 will be described.
In the flow velocity direction meter 1, each of the pair of packers 62 and 72 is formed of a material having water permeability such as an open cell (sponge). Thereby, it is not necessary to provide an air packer, and the measuring instrument main body 10 can be downsized. Further, when the measuring instrument main body 10 is inserted inside the casing pipe P2, the air or groundwater existing below each packer 62, 72 can be extracted (permeated) above each packer 62, 72. . Therefore, the setting of the measuring instrument main body 10 in the casing pipe P2 can be facilitated.
Moreover, in the flow velocity direction meter 1, the tube for pumping gas from the cylinder arrange | positioned on the ground to an air packer becomes unnecessary in connection with the need for an air packer becoming unnecessary. As a result, the number of tubes disposed between the ground and the measuring instrument main body 10 can be reduced. Further, since the piston structure for replacing the distilled water T in the central electrode c of the measuring unit 80 is eliminated, a tube for driving the piston is not necessary.
Further, in the flow velocity direction meter 1, a distilled water tank 52 is arranged in the measuring device main body 10. This eliminates the need for a tube for pumping the distilled water T from the ground to the measuring device main body 10. Therefore, the number of tubes arranged between the ground and the measuring instrument main body 10 can be further reduced.
In particular, in the flow velocity direction meter 1, a permeable body 81 such as a nonwoven fabric or an open cell (sponge) is disposed in the measurement space (measurement unit 80). Thus, the groundwater can be guided and rectified by the permeable body 81. Therefore, it is not necessary to fill the measurement unit 80 with glass beads, and it is possible to reduce the trouble of filling and replacing glass beads. Further, it is not necessary to fill the measurement space with silica sand during measurement, and it is possible to prevent sand accumulation from occurring at the bottom of the casing pipe P2.
Moreover, in the flow velocity direction meter 1, the water permeable body 81 is formed of a material having high water permeability as compared with the material forming the packers 62 and 72. As a result, the outflow of groundwater flowing into the permeable body 81 toward the packers 62 and 72 is suppressed. Therefore, it is possible to suppress the occurrence of upward flow or downward flow in the measurement space, and it is possible to improve measurement accuracy.

  Further, in the flow velocity direction meter 1, the center electrode c has an opening 64 and a discharge port e provided on the downstream side of the opening 64. In particular, the opening 64 is provided in the measurement space, and the discharge port e is provided so that the distilled water T can be discharged to a region below the lower packer 72. Accordingly, the distilled water T can be disposed (replaced) inside the opening 64 by pumping the distilled water T into the center electrode c and discharging the distilled water T from the discharge port e. And the distilled water T arrange | positioned inside the opening part 64 can be moved to the outer side of the opening part 64 with the groundwater which flows through measurement space. Therefore, it is not necessary to install a piston for replacing the ground water with distilled water T in the measuring instrument main body 10, and the measuring instrument main body 10 can be downsized.

In the screen portion 5 of the casing pipe P2, the vertical wire x is embedded inside the horizontal wire y in the thickness direction at the connecting portion between the vertical wire x and the horizontal wire y. Thereby, when the permeable body 81 is disposed in the screen unit 5, it is possible to suppress the generation of the upward flow or the downward flow in the measurement space.
That is, in the screen portion 5, the vertical wire x does not protrude toward the center with respect to the horizontal wire y at the connection portion between the vertical wire x and the horizontal wire y. When arranged, the inner peripheral surface of the horizontal wire y and the permeable body 81 can be brought into contact over the entire circumference of the horizontal wire y. Therefore, generation | occurrence | production of the clearance gap between the internal peripheral surface of the screen part 5 and the permeable body 81 can be suppressed, and it becomes possible to suppress generation | occurrence | production of the upward flow or the downward flow in measurement space.
In particular, according to the flow velocity direction meter 1, as a result of the miniaturization of the measuring instrument main body 10, the bore diameters of the bore hole h and the casing pipe P2 can be reduced. Therefore, the cost required for measurement can be reduced.

(Modification)
As mentioned above, although embodiment of this invention was described, in the said embodiment, a various change is possible.
For example, in the above embodiment, when measuring the flow of groundwater using the flow velocity direction meter 1, the measuring device main body 10 is installed in the casing pipe P2.
However, the measuring instrument main body 10 may be installed inside the boring hole h (bare hole) without installing the casing pipe P2.
At this time, in the flow velocity direction meter 1, the measuring instrument main body 10 can be downsized as described above, and in particular, the vertical dimension can be reduced. Thereby, even when the hole is bent in the boring hole h, it is possible to easily execute the insertion of the measuring device main body 10 into the boring hole h.

DESCRIPTION OF SYMBOLS 1 Flow velocity direction meter 10 Measuring device main body 11 Sensor unit 12 Board | substrate unit 20 Inserting rod 30 Sensor part 40 Distilled water control part 50 Distilled water tank accommodating part 52 Distilled water tank 62 Upper packer 64 Opening part 72 Lower packer 80 Measuring part 81 Permeable body 91 Control board c Center electrode e Discharge port p1 to p12 Peripheral electrode T Distilled water

Claims (6)

A pair of packers,
A measurement area formed between a pair of packers;
A plurality of electrodes arranged in the measurement region;
A permeable body arranged in the measurement region,
The packer is formed of a material having water permeability,
The flow permeable flow meter is characterized in that the water permeable body is formed of a material having high water permeability as compared with a material forming the packer.   The flow rate flow meter according to claim 1, wherein the water permeable body is formed of a nonwoven fabric or an open cell body. A screen formed with a predetermined aperture ratio,
A combination of a plurality of vertical wires and at least one horizontal wire,
A screen characterized in that the vertical wire is embedded inside the horizontal wire in the thickness direction at the connecting portion between the vertical wire and the horizontal wire.   The screen according to claim 3, wherein the horizontal wire is spirally wound. A pair of packers,
A measurement area formed between a pair of packers;
A plurality of electrodes arranged in the measurement region;
A tracer tank in which the tracer is stored;
A tracer pipe connected to the tracer tank,
The tracer pipe has an opening, and a discharge port provided on the downstream side of the opening,
The opening is provided in the measurement region,
The flow outlet is characterized in that the discharge port is provided so that the tracer can be discharged to a region below the lower packer of the pair of packers. A center electrode arranged at the center of the plurality of electrodes,
The flow rate flow meter according to claim 5, wherein the tracer tube is the center electrode.

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