JPS6239946B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the flow of groundwater, and particularly to a method for measuring the flow of groundwater that is suitable when the measurement is carried out by being installed in a borehole or the like.

In recent years, there has been an increasing need to accurately measure the flow of groundwater (velocity and/or direction) to determine whether freezing methods can be adopted for soft ground in civil engineering and construction fields, and to investigate groundwater contamination. It's coming. Conventionally, a so-called tracer method has been widely used as a method for measuring groundwater flow. This method involves drilling multiple boreholes, injecting salt or pigment into one of the boreholes in the center, and examining changes in electrical resistance or concentration over time between the other boreholes, and determining the arrival time and It measures and calculates flow from position. However, in the above-mentioned conventional technology, it is necessary to drill a large number of boreholes, which increases the survey cost, and also requires a long time to measure when the groundwater flow velocity at the measurement location is slow. This has the essential drawback that the groundwater flow often changes due to this, making it difficult to make accurate measurements.

On the other hand, in an attempt to improve the drawbacks of the above-mentioned conventional techniques, Sakuma has devised a method for measuring the flow of groundwater inexpensively and quickly by only drilling one borehole. For example, this method involves lowering a propeller-type current meter as a measuring means into the borehole, and measuring the flow direction and flow velocity from the rotational speed of the propeller and its changes. As in the invention described above, a disk is lowered into a borehole, and the flow condition of groundwater is estimated from the pressure difference due to the upward flow and downward flow of water in the hole acting on the disk.

However, in all of the above-mentioned conventional techniques, the flow is measured by treating the flow of water in the borehole as the flow of groundwater, but when the groundwater flowing in the ground such as a gravel layer reaches the borehole, Turbulent flow occurs due to discontinuity of frictional resistance (soil properties against the flow of groundwater) within the borehole, and therefore, the flow velocity of groundwater is extremely small in a borehole with a relatively small diameter. However, it has the disadvantage that accurate flow measurement is difficult.

Furthermore, in the method of driving a mechanical measuring means using groundwater, when the flow velocity is as small as 2 cm per second or less, it is almost impossible to measure the flow velocity or flow direction due to the influence of frictional force and the like.

The present invention has been made in view of the shortcomings of the prior art, and is capable of easily and highly accurately measuring the flow of groundwater with extremely low flow velocity at a single measurement point. The purpose is to provide a method for measuring flow.

The present invention provides an observation section equipped with a plurality of measurement electrodes, and lowers the observation section into a predetermined groundwater layer in a borehole drilled in the ground, and during or before and after the descent of the observation section. After partially collapsing the hole wall near the depth to be tested and burying the observation section in the ground, a replacement fluid mass with electrical or chemical properties different from that of groundwater is introduced into the groundwater flow. Accordingly, the above objective is achieved by causing a flow within the observation section and detecting and calculating changes in electrical or chemical properties caused by this flow using the measurement electrode.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 13.

FIG. 1 is a schematic explanatory diagram showing an example of actual measurement using a flow measuring device constructed based on the underground water flow measuring method according to the present invention. In the figure, reference numeral 1 denotes a measurement borehole drilled in the ground E from the ground surface to a predetermined depth into the groundwater layer (fine sand layer, medium sand layer, etc.). A casing 2 is driven into the side wall of the borehole 1 to a point above the measurement depth, and this casing 2 prevents the hole side wall 1A from collapsing and isolates the stratum to be measured from other strata. It is beginning to be practiced.

A boring rod 3 is inserted into this borehole 1.
A measurement probe (hereinafter simply referred to as "probe") 4, which is an example of a flow measuring device, is suspended through a test depth, and an observation section provided below the probe 4 is lowered to the test depth. is the hole bottom wall 1B
It is inserted and buried inside. Here, the direction of the probe 4 is confirmed by a compass 5 built into the upper part of the probe 4 (see FIG. 2).
It is designed to be installed and fixed in a predetermined direction.

In the groundwater layer in the ground E, there is a flow of groundwater as shown by arrow F in the figure, and in the borehole 1
Groundwater W gushes out from the groundwater layer, and therefore the probe 4 is immersed in this groundwater W.

The probe 4 is connected by hoses 6, 7 and a cable 8 extending inside the boring rod 3.
It is mechanically and electrically connected to external measuring equipment (not shown), thereby making it possible to measure and record groundwater flow.

FIG. 2 shows a specific configuration of the probe 4 mentioned above. In this figure, reference numeral 9 denotes a cylindrical probe body fixed to the lower end of the boring rod 3, and a head disk 10 made of an insulating material is provided at the lower end of the probe body 9. The lower surface of the head panel 10 is a space to be measured for groundwater flow, that is, an observation section 11 (see the two-dot chain line in FIG. 2). Inside this observation section 11, from the head panel 10, a discharge pipe 12 for discharging replacement fluid and electrode rods 13 for measuring underground water flow are provided.
28 protrudes from the former outlet pipe 12, and a replacement fluid having electrical or chemical properties different from that of the groundwater to be measured (for example, an electrolytic solution such as a NaCl solution if the groundwater has low conductivity) Also, groundwater
When the displacement fluid mass contains NaCl and has a relatively high conductivity, pure water or the like is used), and the movement of this displacement fluid mass can be measured by the latter electrode rods 13 to 28. The observation unit 11 configured in this manner is buried in the bottom wall 1B of the borehole 1, as described later. In addition, when burying the observation part 11, each pouring pipe 12 and the electrode rod 1
For spouting fluid (water etc.) from 3 to 28,
A water supply distributor 29, which is a main part of the fluid ejection mechanism, is built into the probe body 9. This water supply distributor 29 is connected to the first hose 6, and when pressurized water is injected from the outside through the first hose 6, each outlet pipe 30, 31, It has a function of sending out water under equal pressure from 31, . . . In addition, the probe body 6 includes
The above-mentioned direction meter 5 is housed above the water supply distributor 29, and its direction signal is transmitted to the outside via the cable 8.

Next, each configuration of the probe 4 will be explained in more detail.

The head board 10 is screwed to the lower end surface of the probe body 9 with bolts 32, 32, .
As a result, it is attached to the probe body 9 in a hermetically sealed manner. The spouting pipe 12 is planted and fixed in the center of the head board 10 so as to pass through it in the vertical direction, and its lower end extends to the upper part of the observation section 11 . The spout pipe 12 is formed into a double pipe shape as shown in FIG.
There are two outlet pipes 30. On the other hand, the upper end of the outer tube 34 is bent and closed toward the inner tube 30, and the vicinity of the upper end inside the probe body 9 is
As shown in the figure, it is connected to the second hose 7 introduced from the outside through the boring rod 3 via a check valve 35. A nozzle member 36 is fitted to the lower end of the spouting pipe 12, and a pressurized water spout 36A and a replacement liquid Spout 36
B, 36B, ... are drilled (see Figure 7). These replacement liquid spout ports 36A, ... are slightly inclined inward so as to face the axial direction of the spout pipe 12, and porous members 36C, ... are fitted inside to prevent foreign matter from flowing in. . In the spout pipe 12 formed in this way, when pressurized water is sent out from the outside through the first hose 6, the pressure water jet provided at the lower end of the spout pipe 12 passes through the inner pipe 30. Pressure water is jetted downward from the outlet 36A. At this time,
At the same time, when the spout pipe 12 is lowered downward, the jet flow from the pressurized water spout 36A collapses and weakens the hole bottom wall 1B near the spout pipe 12.
can be gradually inserted and buried in the hole bottom wall 1B. On the other hand, when a predetermined amount of replacement liquid is supplied from the outside via the second hose 7, the spout pipe 1
The substitution liquid is poured into the observation section 11 from the substitution liquid pouring ports 36B, . If the replacement liquid is supplied with the observation part 11 buried in the hole bottom wall 1B, the flow of groundwater to be measured will be affected by the presence of the porous member 36C and the groundwater aquifer. It becomes possible to pour out the replacement fluid quietly and in a stable state without disturbing it, and form a desired mass of replacement fluid.

On the other hand, the electrode rods 13 to 28 are implanted and fixed in a state that penetrates the head board 10 concentrically and radially around the above-mentioned extraction pipe 12, and the lower ends of the electrode rods 13 to 28 are , extending below the spouting pipe 12. Specifically, as shown in FIG. 3, outer electrode rods 13 to 20 are arranged concentrically at equal intervals around the spouting tube 12, and correspond to the outer electrode rods 13 to 20. Similarly, inner electrode rods 21 to 28 are arranged concentrically at equal intervals. For this reason, in the embodiment shown in FIG. 3, the electrode rods are arranged radially in eight directions with the extraction tube 12 as the center.

Each of the electrode rods 13 to 28 has exactly the same structure. Of these, the electrode rod 13 will be explained. As shown in FIG. It consists of an equipped outlet pipe 31. This outlet pipe 3
1 is connected to the water supply distributor 29 via a check valve 39. A truncated conical nozzle member 40 is fitted onto the tip of the electrode rod 13, and pressurized water spouts 40A, 4 are connected to the tip and inclined surfaces of the nozzle member 40 and communicate with the outlet pipe 31.
0A,... are drilled (see Figure 5). Therefore, when pressurized water is sent from the first hose 6 described above, a jet flow is generated downward from the tip of the electrode rod 13,
The electrode rod 13 can be buried in the hole bottom wall 1B in exactly the same manner as the spout tube 12 described above.
On the other hand, near the lower end of the electrode rod 13 and slightly below the spouting tube 12 is the insulating coating 38 described above.
An electrode 13A is provided around the . and,
This electrode 13A is connected to the cable 8 in the probe body 9 by a lead wire wired in a long groove 41 carved in the cylindrical member 37. That is,
Each electrode 13A to 28 is provided on the lower surface of the water distribution device 29.
Terminal board 42 for connecting A to an external circuit
The end of the cable 8 described above is fixed to this terminal plate 42, and the electrodes 13A to 28A are individually connected to a signal detection and display means (not shown) provided outside via this cable 8. ). A shield material 43 is fitted into a portion of the long groove 41 corresponding to the electrode 13A, so that the inside of the long groove 40 is hermetically sealed. The observation portion 11 is formed in the vicinity of the electrode rods 13 to 28 by the electrode rods 13 to 28 configured in this way, and
When the electrode rods 13 to 28 are buried in the hole bottom wall 1B, the inside and outside of the observation section 11 are integrally filled with soil forming a groundwater layer, and the soil properties inside the observation section 11 are changed to the groundwater layer. is almost the same as inside, and therefore,
The flow of groundwater moving within the observation section 11 is the same as the flow of groundwater within the actual groundwater layer.

Among the electrodes 13A to 28A, the electrodes forming one direction, for example, the outer electrode 13A and the inner electrode 21A,
25A and the outer electrode 17A constitute a set of measurement electrodes, and at the same time, the inner electrodes 21A and 25A are electrically connected to each other. For example _, when using the difference in resistivity between _the displacement fluid and groundwater, as shown in FIG. The resistance (liquid resistance) RX ₂₁ between the inner electrode 21A and the resistance RX ₂₅ between the other inner electrode 25A and the other outer electrode 17A are bridge-connected. After applying a predetermined AC voltage between them, the fixed resistor
This is to measure the change in the voltage V ₂₅ between the terminal S between R ₁ and R ₂ and the inner electrode 21A or 25A. When the measurement circuit 44 as a signal detection and display means is configured in this way, by discharging a predetermined amount of replacement fluid, for example, a small amount of electrolyte 45 from the central spout pipe 12 installed in the head panel 10, The electrolytic solution 45 moves inside the observation unit 11 together with groundwater and is sent out to the outside, but during this time, the resistance RX ₂₁ between the one outer electrode 13A and the inner electrode 21A, or the other inner electrode 25A Since the resistance value of the resistor RX ₂₅ between the outer electrode 17A and the outer electrode 17A changes sequentially, this change in resistance can be interpreted as a change in the measurement voltage V ₂₅ described above. Other collinear electrodes, such as outer electrode 14A,
The inner electrodes 22A, 26A and the outer electrode 18A are similarly configured, and voltage changes are individually measured in each bridge circuit.

Next, the overall operation of the embodiment will be explained.

First, the probe 4 is lowered into the borehole 1 while being oriented in a predetermined direction using the compass 5, and when it reaches near the bottom wall 1B of the hole, pressurized water is sent from the outside via the first hose 6. Then, through the water distribution device 29 and each outlet pipe 30, 31,...
Pressure water is ejected (injected) toward the bottom wall 1B of the hole below from the tip of the spout pipe 12 and each of the electrode rods 13 to 28 (see FIG. 9). When the probe 4 is further lowered while continuing to supply pressurized water, a part of the hole bottom wall 1B is partially removed by the jet flow from each spout pipe 12 and electrode rods 13 to 28, as shown in FIG. Digged down,
Since the flow becomes soft, the spout tube 12 and the electrode rods 13 to 28 are gradually inserted into the hole bottom wall 1B. Then, when the supply of pressurized water is stopped at a predetermined timing, the area around the spout pipe 12 and the electrode rods 13 to 28 is backfilled, and when the probe 4 is further vibrated vertically or pressed downward, it is finally possible to observe the The lower end of the probe 4, including the inside and outside of the portion 11, is buried in the groundwater aquifer (see FIG. 11). Therefore, the observation unit 11 is integrated with the groundwater aquifer and has substantially the same soil properties, thereby providing almost the same flow of groundwater as in the groundwater aquifer.

Next, after the disturbance of groundwater etc. due to the descent of probe 4 and the burial work has subsided, the second
A predetermined amount of electrolytic solution as a replacement fluid is slowly poured out through the hose 7 into the groundwater layer in the observation section 11 as shown in FIG. 12A. At this time, due to the soil properties (frictional resistance to fluid) of the groundwater layer, the electrolyte is discharged extremely quietly, suppressing the occurrence of turbulence. An electrolyte mass 45 is formed. Here, the groundwater W is, for example, the external electrode rod 13→
To explain the case where the electrolyte mass 45 flows in the direction of the external electrode rod 17, as the groundwater flows, the electrolyte mass 45
When the front edge of the electrolyte mass 45 reaches the inner electrode 25A after a time _T1 (see FIG. 12B), the resistance RX ₂₅ between the inner and outer electrodes 25A and 17A starts to change, The voltage V ₂₅ begins to rise (see T ₁ in Figure 13). Thereby, it is detected that the flow direction of the groundwater W is from the external electrodes 13A to 17A. This direction is accurately specified using the above-mentioned compass 5 as a reference. Subsequently, time T ₂ elapses, and the electrolyte mass 45 is attached to the inner electrode 25.
When the voltage V 25 is transferred between A and the outer electrode 17A (see FIG. 12C), the voltage V ₂₅ shows a peak. In this case, when the width of the electrolyte mass 45 is relatively large, the peak value of the voltage V ₂₅ is maintained until the left edge of the electrolyte mass 45 reaches the inner electrode 25A, that is, from time T ₂ to T ₃ . continues (see Figure 13). Therefore, after the electrolyte mass 45 reaches the other inner electrode 25A, it further advances to the outer electrode 17.
Calculating the time (T ₂ − T ₁ ) to reach A, we get
The distance between the electrodes 25A and 17A is L/
The groundwater flow velocity can now be easily determined by calculating (T ₂ −T ₁ ).

On the other hand, in other measurement electrode groups, for example, the voltage V ₂₄ related to the bridge circuit of the outer electrode 20A, inner electrodes 28A, 24A, and outer electrode 16A is determined by the timing at which the electrolyte mass 45 reaches the inner electrode 24A. Since the voltage V 24 passes behind the timing of reaching the voltage V 25A and barely passes between the electrodes 24A and 16A, the rise of the voltage V ₂₄ is delayed and the peak value is also low (see V ₂₄ in FIG. 12).

Next, when the electrolytic solution 45 flows away together with the groundwater and the voltage V ₂₅ etc. shows a zero value, the electrolytic solution is sent out again through the second hose 7 and observed. Electrolyte mass 45 into part 11
By forming this, the second flow measurement can be started. Such operations can be performed any number of times under the same conditions.

Therefore, in the first embodiment, even if the groundwater layer is a sandy layer, the observation area can be easily and reliably fixed by only spouting a relatively small amount of pressurized water from the tip of each electrode rod. can be buried in the groundwater aquifer to be measured, and therefore, by simply pouring a predetermined amount of electrolyte into the center of the observation section, the flow of groundwater in the actual groundwater aquifer can be extremely controlled. Since accurate measurements can be made and measurements can be repeated any number of times under the same conditions, it is possible to improve measurement accuracy and simplify and speed up measurement work.

In the above-mentioned embodiment, the case where the vicinity of the observation section is buried in the ground has been exemplified, but the entire probe may be back-buried to further improve the measurement accuracy. Alternatively, the jetting of pressurized water may be carried out by incorporating a jetting pump into the probe body and circulating the water in the borehole. Furthermore, the electrolyte may be poured out by incorporating a piston means into the probe body. In addition, as a replacement fluid,
In addition to electrolytes, for example, insulating oil with a high dielectric constant can be used to utilize the difference in capacitance with groundwater, or liquids with different PH values (acid or alkaline solutions)
The replacement with the groundwater may be detected using an electrode for PH measurement, or a composite material mixed with metal particles etc. may be used to improve the measurement sensitivity. Liquid substances (including sol-like substances) that have electrical (resistivity, dielectric constant, etc.) or chemical (PH, etc.) properties similar to those of underground water, and have similar specific gravity and viscosity, as well as corresponding electrodes and measurement circuits. Good to have. Further, the displacement fluid mass may be one in which an ion layer is formed by electric discharge or the like in underground water to be measured. Further, the measurement electrode rods may be arranged not only radially but also in a mesh pattern. Further, a shield electrode having a pressurized water spout may be disposed around the measurement electrode to eliminate external noise such as landmine flow. In addition, the collapse of the hole wall may be carried out by blowing out gas such as air, and if the bottom wall of the hole is soft or sand material, etc. has been put in, blowing out pressurized water may be carried out. The observation section can also be buried by simply pressing down the probe.

Next, a second embodiment will be described based on FIGS. 14 to 19.

This second embodiment has inner electrodes 21A to 2 of the electrodes 13A to 28A in the first embodiment described above.
8A is an annular electrode 50, outer electrodes 13A to 20A are independent electrodes 51 to 58, respectively, and each annular electrode 5
0, the independent electrodes 51 to 58 are formed flush with the lower end surface of the head board 10A (14th
(see figure), each electrode located on the same straight line, including these independent electrodes 51 to 58 and the annular electrode 50, is treated as a group of measurement electrodes, and is used as a signal detection and display means. The measuring circuit 59 is configured as shown in FIG. 16, for example. In this Figure 16
RX ₅₁ indicates the electrical resistance between the independent electrode 51 and the annular electrode 50, and RX ₅₅ indicates the electrical resistance between the independent electrode 55 and the annular electrode 50. Other RX ₅₂ and
RX ₅₆ , etc. are similarly configured and have mutually synchronized analog switches 60, 61.
By sequentially switching and connecting RX ₅₁ and RX ₅₅ , RX ₅₂ and RX ₅₆ , etc., a bridge circuit is sequentially formed for each measurement electrode group, and the measurement voltage is changed in the same way as in the first embodiment described above. V is now being displayed by a multi-channel recorder or the like. Also,
The spout pipe 12 in the first embodiment is connected to the head board 10.
A ring-shaped pouring groove 63 is carved near the outer periphery of the lower end surface of A, and a porous member 62 is fitted inside.
Piping 66, 6 having a distributor 64 and check valves 65, 65 at the tip of the second hose 7 for supplying the replacement liquid
6, . . . are connected to each other, and the pipes 66, 66, . . . are opened into the pouring groove 63. Therefore, when the replacement liquid is introduced from the outside through the second hose 7, the replacement liquid poured out from the pouring groove 63 forms a doughnut-shaped mass of replacement liquid. On the other hand, the spout pipe 1 in the first embodiment
2. In this second embodiment, the ejection parts installed on the electrode rods 13 to 27 are integrated into the head panel 1.
The outlet pipe 67 is opened at the lower end surface of 0A, and is connected to the first hose 6 for supplying pressurized water via a check valve 68.

In the second embodiment configured in this manner, as shown in FIG. 17, when the probe 4A is lowered while jetting out pressurized water from the outlet pipe 67, the bottom wall 1B of the hole is completely covered by the jetted flow. It collapses and becomes weakened,
Therefore, by stopping the ejection at a predetermined timing and pressing down the probe 4A, the observation section 11A on the lower side of the head panel 10A can be easily buried in the groundwater layer, as shown in FIG. Further, after burying the observation section 11A, when an electrolytic solution, for example, is poured out as a replacement solution as shown in FIG. Move near the bottom of 50. At this time, since the electric field generated between each electrode extends into the groundwater layer, the resistance change due to the movement of the electrolyte mass 45A is detected by each electrode, and since the electrolyte mass 45A is donut-shaped, ,
Be sure to cross under one of the electrode groups, as shown in Figure 19B,
Since the water moves as indicated by C, groundwater flow can be reliably measured in the same manner as in the first embodiment.

Therefore, even with this configuration, in addition to achieving the same effects as those of the first embodiment described above, there is an advantage that the configuration can be simplified and durability can be increased.

Note that in this second embodiment, the independent electrode 51
58 may be arranged inside the annular electrode 50.
Furthermore, if the bottom wall of the borehole has been weakened in advance or soft ground, sand, etc. have been introduced during excavation of the borehole, the probe may simply be pressed down without jetting out pressurized water.

Next, a third embodiment will be explained based on FIGS. 20 to 22.

In this third embodiment, the ejection part in the first embodiment described above is provided on the side of the probe.
To explain this more specifically, the first hose 6
Check valve 7 from water distribution distributor 29B connected to
The lead-out pipes 71, 71, . . . are arranged horizontally up to the side wall of the probe body 9B via the probes 0, 70, . In the head board 10B, electrode wires 72 to 87 are implanted in place of the electrode rods 13 to 28 of the first embodiment, and a spouting pipe 12B is provided protruding from the center. This spouting pipe 12B is connected to the second hose 7 via a check valve 88, and is configured to be able to spout the replacement liquid from a porous member 89 fitted into the tip. The displacement of the replacement liquid poured out from the pouring pipe 12B can be measured by the electrode wire groups 72 to 87 using a measurement circuit 44 that is exactly the same as in the first embodiment. There is.

In this third embodiment, after the probe 4B is lowered and installed near the hole bottom wall 1B as shown in FIG. 22A, when pressure water is jetted from the outlet pipes 71, 71, . The electrode wire 72 is collapsed as shown in FIG.
~87, that is, the observation section 11B will be gradually backfilled (see FIG. 22C). Therefore, in addition to producing the same effects as in the first embodiment described above, the observation unit 11B can be operated while the probe 4B is fixed.
Since the probe 4B can be buried, the orientation of the probe 4B can be reliably set in a predetermined direction, and the burying work is also facilitated. Further, since no excessive force is applied to the electrode wires 72 to 87 or the head board 10B, there is no need to strengthen them, and the probe 4B will not be damaged. Furthermore, because the observation section and the spout section are separated, pressurized water will not penetrate into the observation section and disturb measurements. still,
In this third embodiment, each measuring electrode and spout pipe are placed on the head board 10 as in the second embodiment described above.
It may be formed flush with the B side. Also,
As shown in Fig. 23, the pressure water is ejected using a double pipe structure around the probe body, with a discharge port 90 on the side.
A, 90A, .
According to the example shown in FIG. 23, the outer tube section 90 can perform the protective function of the probe main body section 91. Further, as shown in FIG. 24, a second hose 7 is disposed outside the boring rod 3, and an annular water distribution device 29C and this water distribution device 29C are provided.
Outlet tubes 92, 92, . . . having nozzles 92C, 92C, .

Next, a fourth embodiment will be described based on FIGS. 25 to 29.

In this fourth embodiment, in the third embodiment described above, the replacement liquid is also used as the jetting liquid for burying, and the entire probe is completely back-buried in the ground. That is, a connecting pipe section 100 is provided at the lower end of the boring rod 3 and is detachably screwed to the boring rod 3, and the probe 4D is attached to the lower side of this connecting pipe section 100. . This probe 4D has four fins 101, 101 in the vertical direction on the outer circumference of the probe body 9D.
... is installed, and these fins 101, 10
By backfilling the portions 1, . . . , the probe 4D can be fixed non-rotatably. On the other hand, inside the probe body 9D, a cable 8 and a pressure-resistant hose 6D are installed extending from the outside via the connecting pipe portion 100 and seal plugs 102 and 103 fitted with rubber members. This pressure hose 6D has a solenoid valve 10.
The distributor 105 is further connected to the distributor 105 through the probe body 9D, and the distributor 105 has lead-out pipes 106, 106, . The fins 101, 101, . . . have openings at their tip surfaces. Further, the spout pipe 12D formed in the same manner as in the third embodiment is connected to the solenoid valve 10.
4 and is connected to a pressure-resistant hose 6D, and the other components are formed exactly the same as in the third embodiment.

In the probe 4D configured in this manner, a replacement liquid having electrical and chemical properties different from those of groundwater is fed into the pressure hose 6D. First, when burying the observation section 11D of the probe 4D, the solenoid valve 104 is switched to the distributor 105 side by external operation, and then high-pressure replacement liquid is fed through the pressure-resistant hose 6D. Then, the replacement liquid is ejected sideways from the tips of the outlet pipes 106, 106, .
A is collapsed, and as shown in Fig. 27, the observation section 11
D is buried. The displacement liquid 45D spouted out at this time has spread to the surroundings of the observation area as shown in Figure 28A, and therefore, as the groundwater flows, the displacement liquid mass 45D moves as shown in Figures B and C. Therefore, the flow of groundwater can be measured in substantially the same manner as in the first embodiment described above. Further, by pouring out the replacement liquid again from the outlet pipes 106, 106, . . . , repeated measurements can be performed.
Separately, if you wish to measure long-term groundwater flow, first bury the observation section in the same manner as described above, and then backfill the outer circumferential portion of the probe 4D as shown in FIG. 29A. Said fin 1
Since the probe 4D is fixed by the probes 01, 101, ..., the boring rod 3 can be removed at this point. backfill to near the ground surface (Casing 2
(remove as necessary). At this time, the lid 7 in the first half connecting pipe section 2 is designed to receive pressure after backfilling. Next, after switching the electromagnetic valve 104 to the spout pipe 12D side, if the replacement liquid is gradually fed through the pressure hose 6D, the spout pipe 12
The replacement liquid is poured into the observation section from D, and as shown in Fig. 29B.
As shown in the figure, a desired displacement liquid mass 45E can be repeatedly formed.

According to this fourth embodiment, in addition to producing the same effects as the third embodiment, the replacement liquid can also be used as the ejection liquid for burial, so the configuration is simplified and the probe 4D is completely buried in the ground. Since it can be buried in the ground, rainwater and other intrusion will not occur, improving measurement accuracy and making stable measurement possible over a long period of time.

In each of the above embodiments, the collapse of the hole wall is performed by jetting liquid, but the present invention is not limited to this in any way, and the collapse of the hole wall is performed within the borehole. This may be carried out by jetting and stirring water. Specifically, as shown in FIG. 30, the rotary blades 110, 110, ... provided on the side of the probe body 9F are connected to a motor or the like (not shown).
By rotating or reciprocating the hole, the water in the hole is jetted or stirred, and the hole wall is collapsed using the impact of the water in the hole hitting the hole wall, and the hole wall is relatively soft. It is effective in some cases. In addition, the electrode rod provided at the tip of the probe is formed into a nail shape using a large-diameter, high-strength rigid member, etc., and the electrode rod is repeatedly collided with the hole wall by moving the probe up and down or rotating. The bottom wall may be collapsed and weakened, and electrodes may be inserted into the collapsed ground to bury the observation section.Furthermore, the probe may be formed relatively thick and strong, and a small explosive may be placed around the outer periphery of the probe. Alternatively, a submerged discharge section may be provided and the observation section may be buried by collapsing the hole wall using the impact pressure caused by the explosion or discharge.

As described above, according to the present invention, the observation section for measuring the flow of groundwater is directly buried in the groundwater layer, and by moving the displacement fluid mass to the observation section, the flow of groundwater can be easily and extremely accurately measured. It is possible to provide an excellent groundwater flow measurement method that can be used to measure groundwater flow.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the usage state of the embodiment according to the present invention, Fig. 2 is a longitudinal cross-sectional view showing the first embodiment, Fig. 3 is a plan view of Fig. 2, and Fig. 4 is the diagram of Fig. 2. 5 is a plan view of FIG. 4, FIG. 6 is a partially omitted sectional view of the spout pipe of FIG. 2, and FIG. FIG. 6 is a plan view, FIG. 8 is a circuit diagram showing an example of the signal detection display means, FIGS. 9 to 11, and FIGS. 12A, B, and C.
and Fig. 13 are the action explanatory diagram of Fig. 2, and Fig. 1
4 is a partial sectional view showing the second embodiment, FIG. 15 is a plan view of FIG. 14, FIG. 16 is a circuit diagram as a signal detection and display means according to the second embodiment, and FIGS. 17 to 19. A, B, and C are respectively explanatory diagrams of the operation in FIG. 14, FIG. 20 is a partial sectional view showing the third embodiment, FIG. 21 is a plan view of FIG. 20, and FIG. 22 A, B, and C.
are respectively action explanatory diagrams of FIG. 20, and FIG.
24 is a partially broken outline drawing showing a modification of the one in FIG. 20, FIG. 25 is a partial sectional view showing the fourth embodiment, and FIG.
Plan view of Figure 5, Figures 27 and 28 A, B, C
29A and 29B are respectively explanatory views of the operation of FIG. 25, and FIG. 30 is a schematic diagram showing another embodiment. 1... Borehole, 1A... Hole side wall, 1B... Hole bottom wall, 11, 11A, 11B, 11D... Observation part, 1
3-27... Electrode rod, 50... Annular electrode, 51-58
...Independent electrode, 72-87...Electrode wire, 29,29
B, 29C, ... water distribution device, 30, 31, ...,
67, 71, 92, 106, ... Outlet pipe, 45, 4
5A, 45D, 45E...Displacement liquid mass, 110...Rotary blade.

Claims (1)

[Claims] 1. An observation section equipped with a plurality of measurement electrodes is provided, and the observation section is lowered into a predetermined groundwater layer of a bore hole drilled in the ground, and during the descent of the observation section or Before and after the test, a part of the hole wall near the depth to be tested collapses into mud, and the observation section is buried in the ground.Then, the replacement fluid mass, which has electrical or chemical properties different from groundwater, is converted into groundwater. A method for measuring groundwater flow, characterized in that groundwater is caused to flow within the observation section according to the flow of groundwater, and changes in electrical or chemical properties caused by this flow are detected and calculated by the observation electrode. 2. The underground water flow measurement method according to claim 1, wherein the collapse of the hole wall is carried out by causing fluid to flow against the hole wall by stirring, jetting, spraying, etc. 3. The underground water flow measuring method according to claim 1, wherein the collapse of the hole wall is performed by driving a nail-like member into the hole wall. 4. The underground water flow measuring method according to claim 1, wherein the collapse of the hole wall is performed by applying impact pressure such as explosion or electric discharge to a part of the hole wall near the depth to be tested.