JPH0246904B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for measuring minute flow velocity and flow direction of groundwater, and an object of the present invention is to improve the accuracy of measured values and simplify the measurement.

(Prior Art) Various problems have been raised regarding groundwater, which plays the most important role among water resources, such as its contamination.

Therefore, it is important to know the extent and extent of groundwater contamination and to accurately understand the movement of groundwater, and in particular, various studies have been conducted on methods for determining the flow velocity and direction of groundwater.

A typical method is to lower a current meter with a rotating propeller in flowing water into a borehole and measure the flow speed and direction based on changes in the propeller rotation speed. As disclosed in 2007, an attempt was made to lower a disk into a borehole and estimate the flow condition of groundwater from the pressure caused by the upward and downward flow of water in the hole acting on the disk, or to estimate the flow condition of groundwater from the pressure caused by the upward flow and downward flow of water in the borehole, or to inject radioisotopes (RI) into flowing water. There is an attempt to measure the flow velocity and flow direction by tracing changes in the radiation dose distribution due to flowing water.
However, with methods of driving mechanical measuring means using flowing water, it is extremely difficult to accurately measure flow velocities of less than 2 cm per second, and methods that use radioactive materials require a license and cannot be handled properly. Not only is this difficult, but the equipment becomes extremely expensive.

Therefore, in order to further solve these problems, the present inventors arranged a plurality of electrodes at equal intervals with respect to a specific electrode, and the potential difference (electrical resistance value difference) of each electrode between the specific electrode and the change A method for measuring groundwater trends has been developed and has already been put into practical use.

(Problems to be Solved by the Invention) However, in the above method, NaCl solution or a solution containing a radioactive substance such as RI is used as the tracer material (tracking agent) to be first injected between the electrodes, which may cause environmental pollution. Not only is there a problem, but there is also the problem that the accuracy of test values cannot be accurately confirmed because the tracer material is installed only once and cannot be set repeatedly. Not only is it uneconomical because the equipment for injecting the tracer material is complicated and inevitably large, the measuring instruments are large-scale, but it is also extremely difficult in practice to supply a precise amount of tracer material between each electrode. There are limits to the accuracy of measured values, and a certain amount of measurement error is considered unavoidable.

(Means for Solving the Problems) In order to solve the problems of the prior art described above, the present invention significantly improves the measurement accuracy. It consists of an outer shell and an electrode chamber suspended from the lower end of the outer shell. a spouting section that supplies a fixed amount of solution from the solution tank chamber into the electrode chamber; and a solution supply means for supplying an amount of solution.

(Example) An embodiment of the present invention will be described below based on the illustrated embodiment. Reference numeral 1 denotes a hollow cylindrical outer body, and 8 a spouting part installed in the lower part of the inner part of the outer shell. , 20 represents an electrode chamber suspended from the lower end of the outer shell.

The outer shell 1 has a solution tank chamber 3 above, a flexible thin film 4 made of rubber stretched over the outer opening of the solution tank chamber, and a pressure balance room between the thin film 4 and the outer shell 1. Furthermore, a plurality of through holes 6 communicating inside and outside are provided on the peripheral surface of the outer shell 1 corresponding to the pressure balance room 5, and balance filters are interposed in the through holes. Note that the solution tank chamber 3 is filled with distilled water.

The electrode chamber 20 includes a bottom plate 1a at the lower end of the outer shell 1.
It is suspended from the lower end of the bottom plate 1a by a long bolt or the like so as to be able to move downward by a certain distance, and the upper end is fixed directly below the spout hole 1b drilled in the center of the bottom plate 1a. A specific electrode 21 having a cylindrical shape with its lower end fixed to the center of the electrode holding plate 24 and serving as a strainer with a number of through holes perforated on its circumferential surface, and A plurality of electrodes 2 are provided between the bottom plate 1a and the electrode holding plate 24 at equal intervals.
2, and a fixed cylindrical shape having a large number of through holes around the entire circumference of the bottom plate 1a and the electrode holding plate 24 at a certain distance from each electrode. guard mesh 23
The above-mentioned specific electrode 21
A large number of granules 25 are filled between the outside of the guard mesh 23 and the inside of the guard mesh 23, and a flexible net 27 is stretched around the outer periphery of the guard mesh 23 to cover it. Moreover, a large number of pack beads 28 are filled between the net 27 and the guard mesh 23.

On the other hand, the spouting part 8 is fitted into a cylinder 9 which is located inside the lower part of the outer body 1 and fixed to the center of the upper surface of the bottom plate 1a, and is fitted into the cylinder so as to be movable in the vertical direction. A piston 10 has an integral inner tube 15 that enters into the specific electrode 21 and is movable upwards from within the specific electrode 21 when rising. A fixed tube 16 that penetrates and faces into the hollow chamber 10a of the piston 10, a hose 17 that communicates between the fixed tube 16 and the solution tank 3, and a liquid supply and drainage pipe that communicates with the upper chamber of the cylinder 9. 13, and a liquid supply/drainage pipe 14 communicating with the lower chamber of the cylinder 9.

Note that opening/closing valves 18 and 19 are attached to the distal ends of the fixed tube 16 and the inner tube 15, respectively. Further, above the outer shell 1, a gyroscope device 26 is installed, which is an ultra-miniaturized gyroscope that is commonly used for controlling the attitude of aircraft and ships.

(Function) In the configuration of the embodiment described above, the apparatus shown in FIG. 1 is lowered into the borehole to the measurement depth. At this time, the pack beads 28 in the electrode chamber and its surrounding surface are stretched downward due to the weight of the lower packer and cylinder (not shown) suspended below the electrode holding plate 24. When a predetermined depth is reached and the lower strainer is inflated and fixed to the inner wall surface of the strainer 29, a piston (not shown) moves downward in the cylinder due to the weight of the measuring instrument body. At the same time, the pack beads 28 provided around the electrode chamber 20 are compressed from above and below. The pack beads 28 gradually become thicker as they are compressed in the vertical direction, expand in the radial direction, and are pressed against the inner wall surface of the strainer 29. Further, in advance, pressurized liquid is fed into the upper chamber of the cylinder 9, the piston 10 is lowered, the inner tube 15 is inserted into the specific electrode 21, the valve 18 is opened, and the valve 19 is kept closed. A certain amount of distilled water is poured out from the tank 3 into the inner tube 15 through the hollow chamber 10a of the piston.

After that, valve 18 is closed and valve 1 is closed.
Lower chamber 12 of the cylinder with 9 open.
When the pressure liquid in the upper chamber 11 is drained, the inner tube 15 is pulled up from the specific electrode 21 as the cylinder 10 rises, and only the distilled water (test solution) changes in volume. It remains in the specific electrode 21 without causing any damage.

In this state, a constant weak current is applied between the specific electrode 15 and each electrode arranged radially around the specific electrode 15, and the change in resistance between each electrode is measured by a voltage indicator (not shown) installed on the ground. ) to know the flow velocity and flow direction of groundwater.

Specifically, when groundwater flows into the electrode chamber 20 through the guard mesh 23, the distilled water in the central specific electrode 21 is diluted by replacement with the inflowing groundwater, and the distilled water gradually flows into the center of the electrode chamber 20. When the specific electrode 21 is pushed outward from the electrode chamber 20 through a large number of through holes and reaches one of the radially arranged electrodes, the resistance value of the electrode changes. The minute flow velocity and flow direction of groundwater can be measured depending on the mode and time.

In the above case, the pressure balance room 5
Groundwater constantly enters and exits the chamber through the balance filter 6, and the water pressure can be directly transmitted to the distilled water in the solution tank 3 through the thin film 4, so that the water pressure in the electrode chamber 20, which is in contact with the groundwater, is The water pressure in the solution tank 3 is always kept in equilibrium.

Furthermore, when the flow velocity and direction measurement work is completed and measurement is to be performed again, pressure liquid is pumped into the upper chamber 11 of the cylinder, the cylinder 10 is lowered, the inner tube 15 is inserted into the specific electrode 21, and the valve 18 is closed. By opening the inner tube 15, closing the valve 19, and filling the inner tube 15 with distilled water by the same operation as described above, and further allowing this to remain in the specific electrode 21, it is possible to continue repeated measurement operations. be.

Further, by utilizing the gyro device 26, it is possible to immediately know the orientation of a specific part of the measuring device.

(Effects of the Invention) As described above, the present invention has a solution tank chamber in the outer shell and a pouring section for supplying a fixed amount of solution from the solution tank chamber into the electrode chamber, and the pouring section is provided with a cylinder mechanism. Since it is composed of an inner tube that can freely retract toward the center of the electrode chamber and a solution supply means that supplies a certain amount of solution into the inner tube, when supplying the solution to the center of the electrode chamber, the As a result of the solution being constantly supplied in a fixed amount to the correct position without causing any volume change, not only the accuracy of the measured values is significantly improved, but the entire device can also be made smaller, making it even more convenient to handle. It can be done.

In addition, the electrode chamber is surrounded by a net-like guard mesh, and the inside of the electrode chamber is filled with a large number of granules, and a large number of puncture beads are also arranged and wrapped around the outer periphery of the above-mentioned mesh guard mesh. Therefore, the flow lines of the groundwater flow are not distorted, and the natural flow of the groundwater flow within the electrode chamber can be maintained.

In addition, a flexible watertight sheet is attached to at least a portion of the solution tank chamber, and one or more balance filter holes are formed on the circumferential surface of the outer body in correspondence with the exposed position of the watertight sheet. Groundwater pressure is transmitted to the solution in the solution tank chamber through the balance filter, and the solution and the water pressure in the electrode chamber can always be maintained in equilibrium, contributing to further improvement of measurement accuracy.

Furthermore, since a miniaturized gyro device is built into the outer shell, the orientation of a specific part of the measuring device can be immediately known even at a deeper position than before, making it possible to easily align the measuring device as in the past. Inconveniences and inaccuracies can be resolved.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an apparatus for measuring the minute current velocity and flow direction of underground water, which is an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Outer body, 3...Solution tank chamber, 4...Flexible thin film, 5...Pressure balance room, 6...Through hole, 8...Spout part, 9...Cylinder, 10...
Piston, 15... Inner tube, 16...
Fixed tube, 18, 19...Opening/closing valve, 20
... Electrode chamber, 21 ... Specific electrode, 22 ... Electrode,
23... Guard mesh, 25... Granular matter, 26
... Gyroscope device, 27 ... Flexible net, 28
...Patsuku beads.

Claims (1)

[Scope of Claims] 1. Consists of a hollow cylindrical outer body and an electrode chamber suspended from the lower end of the outer body, and the electrode chamber has a plurality of electrodes arranged at equal intervals for each specific electrode. The electrodes are arranged opposite each other, and the outer body has a solution tank chamber and a spouting section for supplying a fixed amount of solution from the solution tank chamber into the electrode chamber, and the spouting section is connected to the 1. A device for measuring minute flow velocity and flow direction of underground water, comprising an inner tube that is freely retractable into an electrode chamber, and a solution supply means that supplies a certain amount of solution into the inner tube. 2. In the device set forth in claim 1, the electrode chamber is surrounded by a mesh net, and the inside of the electrode chamber is filled with a large number of granular materials. and flow direction measuring device. 3. In the item set forth in claim 1, the specific electrode within the electrode chamber is located at a distance from the inner tube that is provided at the center of the chamber and at the protruding and retracting position of the inner tube that protrudes and retracts into the chamber. A device for measuring the minute flow velocity and direction of underground water using a large-diameter electrode strainer. 4. In the device described in claim 1, the solution supply means for supplying a certain amount of solution into the inner tube recessed and recessed into the electrode chamber is provided in a cylinder for advancing and retracting the inner tube from the direction of movement of the cylinder. Groundwater microflow velocity and flow direction measuring device which is a fixed tube inserted airtight. 5. In the product described in claim 1, a flexible watertight sheet is attached to at least a part of the solution tank chamber, and a flexible watertight sheet is attached to the circumferential surface of the outer body in correspondence with the exposed position of the watertight sheet. A device for measuring the microflow velocity and flow direction of groundwater, which is formed by opening one or more balance filter holes. 6. A device for measuring the minute flow velocity and flow direction of groundwater as set forth in claim 1, which comprises a gyroscope built into the outer body.