JPH0641986B2 - Measurement method of groundwater flow velocity and flow direction - Google Patents

Description

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

(Prior Art) Regarding groundwater that plays the most important role in water resources,
Various problems have been raised due to such pollution.

Therefore, it is important to know the extent and range of groundwater contamination and to accurately understand the movement of groundwater. Especially, various methods have been studied so far for knowing the velocity and direction of groundwater.

As a typical example, there is a method of lowering a velocity meter in which a propeller rotates with running water into a boring hole, and measuring the flow velocity and the flow direction by changing the number of revolutions of the propeller.
In addition, as disclosed in Japanese Patent Publication No. 45-25029, an attempt is made to lower a disk into a boring hole, and to estimate the flow condition of groundwater from the pressure due to the upflow and downflow of water in the hole acting on the disk, or There is an attempt to measure the flow velocity and flow direction by pouring a radioisotope (RI) into running water and tracing the distribution change of radiation dose due to running water.

However, in the method of driving the mechanical measuring means with running water, for example, it is extremely difficult to accurately measure a flow velocity of 2 cm or less per second, and the method of using radioactive substances requires a license. Is not only difficult,
The equipment becomes extremely expensive.

Therefore, in order to solve these problems, the present inventors provide a plurality of electrodes at equal intervals with respect to a specific electrode, and the electric difference (electrical resistance difference) between each electrode and the specific electrode or We have developed a method to measure trends in groundwater based on changes and have already put it to practical use.

(Problems to be solved by the invention) However, in the case of the above-mentioned conventional method, since a NaCl solution or a radioactive material-containing solution such as RI is used as a tracer material (tracing agent) to be first injected between electrodes, environmental pollution is caused. In addition to the above problem, if the device for injecting the tracer material between the electrodes installed in the well is complicated and inevitably becomes large, the measuring instruments become large and uneconomical. However, since it is extremely difficult to supply the tracer material accurately between the electrodes without losing its shape, the accuracy of the measured values is limited, and some measurement errors are unavoidable. Was there.

Further, the improvement of the above-mentioned measuring instruments largely contributes to the improvement of the measurement accuracy, but this alone has a limit and cannot be perfected.

That is, in the boring hole through which the measuring instruments are lowered, a hydrostatic pressure distribution different from the hydrostatic pressure is made for each aquifer. For example, as shown in FIG. Through the sandy filter B and the through hole D of the strainer C, the groundwater of different aquifers freely moves in the vertical direction as shown by the arrow. Therefore, when there is such a vertical flow velocity of groundwater in the borehole, it is necessary to accurately measure the natural horizontal flow velocity flowing in the ground regardless of the accuracy of the measuring device E installed in the borehole. Is extremely difficult.

(Means for Solving Problems) The present invention solves various problems in the above-mentioned conventional techniques, and particularly prevents vertical flow of groundwater in a borehole to prevent horizontal horizontal flow of groundwater in the ground. It is possible to measure the flow velocity and the flow direction of the electrode with high precision. Specifically, a predetermined current is applied between each pair of electrodes that are immersed in groundwater at equal intervals and within the electrode area. A solution with a specific resistance value different from that of groundwater is poured into and the difference in the electrical resistance value between the electrodes due to the time-dependent displacement of the solution and the change in the electrical resistance value between the electrodes is measured. In the case of measurement, a cylindrical strainer having holes formed at predetermined intervals in the longitudinal direction and at predetermined intervals in the circumferential direction in the boring hole for lowering the measuring device body, and the length of the strainer. Person In the boring hole, which is composed of two or more highly water-absorbing seal lock members fixed to the outer peripheral surface at regular intervals and a pack filter provided between the upper and lower seal lock members on the outer peripheral surface of the strainer. A stabilizer is inserted, and the seal lock is expanded by water absorption and pressed against the wall surface of the hole, and the pack filter existing between the seal locks is pressed to make the wall thicker. The present invention relates to a method for measuring a minute flow velocity and a flow direction of groundwater, which is measured by the measuring device body after stabilizing the inside.

(Embodiment) The concrete contents of the present invention will be described below with reference to the illustrated embodiment, and FIG. 1 shows the first embodiment of the present invention, in which the boring hole 37 has a cylindrical shape. Strainer 40
Also, a plurality of seal lock members 38 are fixed to the outer circumferential surface in the length direction of the strainer with a constant interval, and a flexible flexible bag which is expandable and contractible between the upper and lower seal lock members.
A stabilizing device for boring holes in which the pack filter 39 whose outer peripheral surface is covered by 39a is applied to the outer peripheral surface of the strainer 40 is loaded.

In the above, the cylindrical strainer 40 has through holes 41 at predetermined intervals in the longitudinal direction, and also at predetermined intervals in the circumferential direction of the strainer.

The seal lock member 38 is made of a super absorbent polymer having a donut shape and having a volume that significantly expands about 30 to 60 times due to absorption of water, and examples thereof include carboxymethyl cellulose salt, polyacrylate, and polyethylene. Consideration is also given to the use of cellulosic powdery superabsorbent polymers such as oxides, povals, starch copolymers, and cellulose copolymers, or starch graft polymerization superabsorbent polymers that are particularly excellent in terms of water absorption capacity and water absorption rate. To be

The pack filter 39 has a flexible net bag 39a filled with a large number of bead balls, which are the upper and lower seal locks.
It is mounted between 38 and 38 on the outer peripheral surface of the strainer 40.

Further, the structure of the measuring device main body 1 mounted inside the strainer 40 is shown in detail in FIG. 2 (A).

In the figure, 1 is a hollow cylindrical outer shell, 8
Reference numeral 20 denotes a pouring portion installed below the inside of the outer shell, and 20 denotes an electrode chamber suspended at the lower end of the outer shell.

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

The electrode chamber 20 is suspended below the bottom plate 1a at the lower end of the outer shell 1, and has an upper end fixed directly below a spouting hole 1b formed in the center of the bottom plate 1a and an electrode holding plate at the lower end. A specific electrode 21 which is a cylindrical shape fixed to the center of 24 and also serves as a strainer having a large number of through holes formed in the peripheral surface, and the specific electrode as the center, and these electrodes are provided at equal intervals to each other. Above bottom plate
A plurality of electrodes 22 provided between the electrode holding plate 24 and the electrode 1a, and the periphery of the electrodes 22 are interposed between the bottom plate 1a and the electrode holding plate 24 with a small distance from each electrode. It is composed of an expandable cylindrical guard mesh 23 having a large number of through holes all around, and a large number of granular particles are provided between the outside of the specific electrode 21 and the surface side of the guard mesh 23. Items (pack beads in this embodiment) 25 are filled.

On the other hand, the pouring part 8 is fitted inside the lower part of the outer shell 1 and at the center of the upper surface of the bottom plate 1a, and is vertically movably fitted into the cylinder 9 and, at the time of lowering, from the pouring hole 1b. A piston 10 having an inner tube 15 that moves into the specific electrode 21 and moves upward from the specific electrode 21 when rising, and the upper end is fixed to the center of the upper part of the cylinder 10 and the upper end of the piston 10 is fixed to the upper part. A fixed tube 16 penetrating through and facing the hollow chamber 10a of the piston 10, a hose 17 that connects the fixed tube 16 and the solution tank 3, and a pipe for sending and discharging liquid that communicates with the upper chamber of the cylinder 9. 13 and a pipe 14 for sending and discharging liquid, which communicates with the lower chamber of the cylinder 9.

Opening valves 18 and 19 are attached to the respective tip portions of the fixed tube 16 and the inner tube 15. Further, above the outer shell 1, a gyro device 26, which is a super-model of a gyro generally used for attitude control of aircrafts and ships, is equipped.

An upper packer 29 at the upper end of the measuring device main body having the above-described structure, and a lower copper 28 at the lower end via a connecting portion 27.
Are mounted and loaded into the strainer 40 as shown in FIG. Further, in the same figure, 30 is a directional rod having a square cross section for lowering and raising the measuring device main body along the strainer 40 into the boring hole 37, and for positioning the orientation of the electrode, and 32 is detected at the electrode part. An indicator that converts the specific resistance value into a potential difference and outputs it to the self-recording meter 33, 31 is a capty cord connecting the electrode section to the above indicator, 34 is a power supply, 35 is the piston 10 and valve 18 of the spout part 8. , 19 manual hydraulic pump for opening and closing the ground using hydraulic pressure, 36 is upper packer 29 and lower copper
28 shows a Chisso gas cylinder for inflating 28.

Further, FIG. 2 (B) shows a second embodiment of the present invention. The figure shows the electrode chamber attached to the bottom 1a of the measuring instrument body.
The granular material 25 surrounding 20 is further elaborated, the electrode chamber 20 is fixed to the bottom portion 1a of the measuring device main body, and an expandable mesh 42 is provided around the electrode chamber 20. A wrapped pack bead 25 is provided, and a cylinder 46 having a bottomed cylindrical shape is attached to the lower end of the pack bead 25.

Further, in the cylinder 46, the upper portion is suspended by a suspension bolt 44, and the lower portion of the slit bolt 47 penetrates the bottom portion of the cylinder 46 at a lower portion thereof, and a fixing nut 48 is screwed from the bottom surface thereof. The inside of the cylinder 46 is configured to be slidable in the vertical direction, and the lower packer 50 is connected from the bottom surface of the cylinder 46 through the connecting portion 46.
Can be installed.

FIG. 3 shows a third embodiment of the present invention. In this case, the structure of the measuring instrument main body is basically the same as that of the second embodiment, but the lower packer 50 and the upper packer 51 mounted on the upper and lower sides of the measuring instrument main body have respective side emission directions. Inflatable seal members 52 and 53 protruding to the inside are attached.

The expansive seal members 52 and 53 are basically the same material as the seal lock member 38 shown in FIG. 1, and the volume of the expansive seal members 52 and 53 increases about 30 to 60 times after a few hours due to water absorption. It projects outward from the divided groove portion and is pressed against the wall surface of the boring hole 37.

Further, between the upper and lower expansive seal members 52 and 53 and on the outer peripheral surface of the strainer 40, a pack filter 55 formed by filling a flexible net bag 54 with a large number of bead balls is interposed.

(Operation) In the configuration of each of the above-mentioned embodiments, the seal lock member 38 is provided in the boring hole 37 at regular intervals (corresponding to the distance between the upper and lower packers provided at the upper and lower ends of the measuring instrument body) on the outer peripheral surface, and A boring hole stabilizing device configured by mounting a pack filter 39 filled in a flexible net bag 39a between seal lock members is provided.

Each seal lock member 38 absorbs groundwater and expands several tens of times over a certain period of time. At this time, the pack filter 39 increases its thickness in the radial direction as much as it is pressed from above and below with the expansion of the upper and lower seal lock members 38, and as a result, both the seal lock member 38 and the pack filter 39 have a boring hole 37. It prevents the vertical water flow in the vertical direction in the hole by pressing it against the wall of the hole and stabilizes the strainer 40.

Next, while operating the azimuth rod 30, the measuring instrument main body is lowered to a predetermined depth in the strainer 40, and when the target depth is reached, the lower packer 28 from the Chisso gas cylinder 36 is reached.
Also, pressure gas is sent to the upper packer 29 to expand it and support the main body of the measuring instrument.

In this state, the upper and lower seal lock members 38,
The water flow of each aquifer located between 38 is restricted to flow vertically in the boring hole 37 and moves exclusively as a natural flow in the horizontal direction, so the flow velocity and flow direction are measured in this state. .

For the measurement, the pressure liquid is preliminarily pumped into the upper chamber of the cylinder 9 to lower the piston 10 to move the inner tube 15 to a specific electrode
The valve 18 is opened in the state of being inserted into the valve 21, and a fixed amount of distilled water is poured from the solution tank 3 into the inner tube 15 through the hollow chamber 10a of the piston with the valve 19 kept closed.

Thereafter, when the pressure liquid is pumped into the lower chamber 12 of the cylinder while the valve 18 is closed and the valve 19 is kept open, and the pressure liquid in the upper chamber 11 is discharged, the pressure liquid is identified as the cylinder 10 rises. The inner tube 15 is pulled up from the electrode 21, and only distilled water (test solution) remains in the specific electrode 21 without causing a volume change.

In this state, a constant weak current is applied between the specific electrode 15 and each electrode radially arranged around the specific electrode 15, and the change in the resistance value between the electrodes is measured by the voltage indicator 32 installed on the ground. To know the flow velocity and direction of groundwater.

Specifically, groundwater is passed through the guard mesh 23 to the electrode chamber 20.
When it flows into the inside, the distilled water that was inside the specific electrode 21 inside is replaced and diluted with the inflowing groundwater, and the distilled water gradually becomes
When it is pushed out of the specific electrode 21 in the center of 20 through a large number of through holes toward the outside of the electrode chamber 20 and reaches any of the radially arranged electrodes, the resistance value of the electrode changes. Therefore, the groundwater minute flow velocity and flow direction can be measured depending on the mode and time of the change.

In the above case, the groundwater always flows into and out of the pressure balance room 5 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 groundwater contacts the groundwater. Electrode chamber
The water pressure in 20 and the water pressure in the solution tank 3 are always in equilibrium.

Further, when the flow velocity direction measurement work is completed and the measurement is performed again, the pressure fluid is pumped into the upper chamber 11 of the cylinder, and the cylinder 10 is lowered to insert the inner tube 15 into the specific electrode 21 and the valve 18 is set. Open and close the valve 19 to fill the inner tube 15 with distilled water by the same operation as described above.
By leaving it inside, it is possible to continue the measurement work as it is.

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

In the structure of the second embodiment shown in FIG. 2 (B), when the measuring instrument main body is lowered along the strainer 40, the pack beads 25 are placed in the lower packer 50 and the cylinder 46.
It is in a state of being extended downward due to the weight of the cylinder 46 when it is fixed to the inner wall surface of the strainer 40 by reaching the predetermined depth and inflating the lower packer 50. Piston 45 in
Moves downward, and along with this, the packed beads 25 mounted around the electrode chamber 20 are compressed in the vertical direction. The pack beads 25 gradually become thicker as they are compressed in the vertical direction, expand radially, and are pressed against the inner wall surface of the strainer 40.

Further, in the structure of the third embodiment shown in FIG. 3, the expandable seal members 52 and 53 provided on the respective side surfaces of the upper and lower packers 50 and 51 are provided on the strainer 40 and are symmetrical in the longitudinal direction. After moving to a predetermined depth position of the strainer 40 along a plurality of split grooves (not shown) provided in the position, the expandable seal members 52, 53 are rotated in the circumferential direction to move from the split grooves. It is removed, placed in an arbitrary through hole 41, and left. The expansive seal members 52, 53 absorb the groundwater after only a few hours to increase the volume and expand, and press against the wall surface of the hole and at the same time further press the pack filter 55 from above and below. The pack filter 55 can increase the thickness by the amount of pressure from the vertical direction and also press-contact with the hole wall surface to fill the space between the hole wall and the strainer 40.

(Effect of the invention) As described above, the present invention lowers the measuring device main body into the boring hole to measure the minute flow velocity and flow direction of groundwater. Also, a cylindrical strainer having through holes formed at intermittent positions, a highly water-absorbing seal lock member fixed to the outer circumferential surface in the longitudinal direction of the strainer with a gap of one, and upper and lower seal lock members. In the space between the seal locks, a boring hole stabilizing device consisting of the pack filter provided on the outer peripheral surface of the strainer is inserted, and the seal lock is expanded by water absorption and pressed against the wall surface of the hole. The filter was pressed to make it thicker, and this was pressed against the wall surface of the same hole to stabilize the inside of the boring hole, and then the measurement was performed with the measuring device body. As a result, groundwater in different aquifers can reliably block vertical water flow that moves freely up and down in the boring hole and can be limited to only the horizontal flow of each layer, It is possible to perform high-precision measurement, which has been limited by improving the precision of the conventional measuring device only.

In addition, the measuring device main body also has a solution tank chamber inside the outer shell and a pouring portion for supplying a fixed amount of the solution from the solution tank chamber to the electrode chamber, and the pouring portion is directed toward the center of the electrode chamber by a cylinder mechanism. Since it is composed of an inner tube that can be retracted and retracted and a solution supply means that supplies a fixed amount of solution to the inner tube, the volume of the supplied liquid changes when the solution is supplied to the center of the electrode chamber. As a result of being quantitatively supplied to an accurate position,
Not only the accuracy of the measured value is remarkably improved, but also the entire apparatus can be downsized, and the handling can be made more convenient.

Furthermore, the electrode chamber is surrounded by a mesh net, and since many granular materials are filled inside the electrode chamber, the flow line of the groundwater flow is not distorted, and the natural flow of groundwater flow in the electrode chamber is prevented. Can be maintained.

Further, since a flexible watertight sheet is attached to at least a part of the solution tank chamber, and one or more balance filter holes are formed on the peripheral surface of the outer shell corresponding to 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 be always kept in equilibrium, which contributes to further improvement in measurement accuracy.

Furthermore, since the miniaturized gyro device is incorporated in the outer shell, the orientation of the specific part of the measuring device can be immediately known even at a position deeper than the conventional one. Various beneficial effects such as inconvenience and inaccuracy can be solved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a boring hole and a stabilizing device in the boring hole for measuring a minute flow velocity and a flow direction of groundwater, which is an embodiment of the present invention, and FIG. 2 (A) is a boring hole. 2B is a longitudinal sectional view of a main part of an electrode chamber portion of the measuring device main body, and FIG. 3 is another embodiment of the present invention. An example is a vertical cross-sectional view of the main part of a boring hole and a stabilization device in the boring hole for measuring the minute flow velocity and flow direction of groundwater. Fig. 4 is a conventional boring hole for measuring the flow velocity and flow direction of groundwater. The longitudinal sectional view of the main part of is shown. 1 ... Outer body, 3 ... Solution tank chamber 4 ... Flexible thin film 5 ... Pressure balance room 6 ... Through hole, 8 ... Pouring part 9 ... Cylinder, 10 ... Piston 15 ... Inner Tube 16 …… Fixed tube, 18,19 …… Open / close valve 20 …… Electrode chamber, 21 …… Specific electrode 22 …… Electrode, 23 …… Guard mesh 25 …… Granular material, 26 …… Gyro device 28 …… Lower part Packer, 29 …… Upper packer 30 …… Rod 31 …… Cap tire code 32 …… Indicator, 33 …… Recorder 34 …… Power supply, 35 …… Manual hydraulic pump 36 …… Cisso gas cylinder 37 …… Boring hole 38… ... Seal lock member 39 ... Pack filter 39a ... Flexible net bag 40 ... Strainer, 41 ... Through hole 42 ... Mesh, 43 ... Net 44 ... Hanging bolt, 45 ... Piston 46 ... Cylinder, 47 …… Slide bolt 48 …… Fixing nut, 49 …… Forming unit 50 ...... lower packer, 51 ...... upper packer 52, 53 ...... inflatable sealing member 54 ...... net bag 55 ...... pack filter

Claims (3)

[Claims] 1. A predetermined electric current is applied between each pair of electrodes immersed in groundwater at equal intervals, and a solution having a specific resistance value different from that of groundwater is poured into the electrode region to separate the solution and groundwater. When measuring the flow velocity and flow direction of groundwater using a measuring instrument body that measures by the difference or change in electrical resistance value between electrodes due to the replacement with time, there is a longitudinal direction in the boring hole that lowers the measuring instrument body. A cylindrical strainer having through holes formed at predetermined intervals in the circumferential direction and at predetermined intervals also in the circumferential direction, and a highly water-absorbing seal fixed on the outer circumferential surface in the longitudinal direction of the strainer with a constant interval. A boring hole stabilizing device consisting of a lock member and a pack filter provided between the upper and lower seal lock members and provided on the outer peripheral surface of the strainer is inserted, and the seal lock is expanded by water absorption to expand the hole. While pressing it against the surface and pressing the pack filter existing between the seal locks to make it thicker, press the same against the wall surface of the hole to stabilize the inside of the boring hole, and then perform the measurement with the measuring instrument body. Method for measuring minute velocity and flow direction of groundwater. 2. The measuring device according to claim 1, wherein a pair of packers are mounted on the measuring device main body in the vertical direction, and the packing is expanded and brought into pressure contact with the inner wall surface of the strainer. A method for measuring the minute flow velocity and flow direction of groundwater in which the main body is fixed at a predetermined depth in the borehole. 3. A highly water-absorbing seal lock member fixed to the outer circumferential surface in the longitudinal direction of a strainer at regular intervals, and between the seal lock members according to claim 1. The pack filter applied to the outer peripheral surface of the strainer has a ring-shaped seal lock projecting in the circumferential direction from the side surfaces of a pair of packers provided in the up-down direction of the measuring device body loaded in the strainer. A method for measuring the minute flow velocity and flow direction of groundwater in which a pack filter is interposed between a pair of protruding seal locks while protruding outward from notched long grooves provided at predetermined intervals in the longitudinal direction.