JP2586735B2 - Measuring method and measuring device for groundwater flow direction and flow velocity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the flow direction and flow velocity of groundwater by a thermal neutron method, a calorimetric method or a potentiometric method.

[0002]

[Prior Art] In construction work, etc., including underground water,
It is necessary to measure the direction and velocity of groundwater flow for each stratum. As one means of this measurement method, Japanese Patent Publication No. 60-27
A thermal neutron method using a thermal neutron detector proposed in U.S. Pat. No. 388 as a groundwater flow direction and an anemometer is known.

In order to measure with a thermal neutron detector, a vertical hole is drilled in the target ground, a measuring pipe having a strainer is installed in the vertical hole, and the thermal neutron detector is inserted into the pipe. Then, a tracer having a large neutron absorption cross-sectional area, for example, an aqueous boron solution, is supplied to the periphery thereof.
Since the tracer is governed by the flow of groundwater and flows and is diluted, the concentration of the tracer can be measured by detecting the thermal neutron count rate in each direction with a thermal neutron detector. It becomes possible to know.

As means for measuring the flow direction and flow velocity of groundwater, in addition to the above-described thermal neutron method, a calorimetric method using heat as a tracer, a potential difference method using distilled water as a tracer, and the like have been proposed. Both methods are the same in that a flow direction and a flow velocity meter are inserted into a measurement pipe installed in a vertical hole, and the flow direction and the flow velocity are measured.

[0005]

However, in the pressurized water ground, a vertical groundwater flow occurs in the drilled pit, which makes it difficult to measure the flow direction and the flow velocity. When a plurality of confined aquifers are present in an overlapping manner, the number of confined aquifers must be measured by drilling a vertical hole for measurement. For this reason, a large space was required for the survey and measurement for a long period of time, and the cost was high.

The present invention has been made in view of the above problems. The aim is to propose a measuring method and measuring device that can accurately measure the direction and velocity of groundwater by drilling a single pit, even if the ground has multiple confined aquifers. It is in.

[0007]

The measuring method according to the present invention comprises:
(A) A pit is drilled in a confined aquifer ground where a plurality of confined aquifers separated by an impermeable layer overlap and a measuring pipe having a strainer portion is installed in the pit. A step of closing the gap between the pipe and the pit at the position of the permeable layer by filling with a waterproof material; And a step of inserting a measuring rod attached below into the measuring pipe, and (C) an upper and lower impermeable layer of one aquifer to be measured by expanding outer tank packers of the upper and lower waterproof packers. Position is fixed to the inner surface of the pipe for measurement, and the gap between the pipe for measurement and the rod is mostly closed, and the expansion and contraction of the inner tank packer of the vertical water stop packer fixes the rod at the time of inflation and the pipe and rod for measurement. Completely closes the gap between To allow the movement of the upper and lower rod,
Measuring the flow direction and flow velocity of the groundwater at each depth of the same aquifer at the time of expansion; (D) shrinking the outer tank packer of the upper and lower water stop packers to release the fixing with the measuring pipe, Moving to the next aquifer position, (C),
(D) Repeating the process, groundwater flow direction of all aquifers
A method for measuring the flow direction and flow velocity of groundwater, comprising measuring a flow velocity. (A) A confined zone in which a plurality of confined aquifers separated by an impermeable layer overlap and exist. A measuring rod to be inserted into a measuring pipe having a strainer portion in which a vertical hole is drilled in the water ground and a gap between the vertical hole at the position of the water-impermeable layer and the pipe is closed by filling with a waterproof material, B) A water stop packer is disposed at a position above and below the groundwater flow direction and current meter on a rod on which the groundwater flow direction and current meter is mounted, and the water stop packer surrounds the rod in a cylindrical shape and is concentric. The inner and outer tank packers are separated by a partition wall. Characteristic groundwater flow direction and flow Of the measuring device, it is.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ground to be measured in this embodiment is shown in FIG.
As shown in, the first, second and third confined aquifers 1-1,
1-2, 1-3 are confined aquifer grounds that overlap and exist,
The aquifer is partitioned by impermeable layers 2-12 and 2-23, and the groundwater level of the confined aquifers 1-1, 1-2 and 1-3 is 3
At -1, 3-2, and 3-3, those in the lower layer increase in order.

The flow direction and flow velocity of the groundwater on this ground are measured by the following procedure.

(1) As shown in FIG. 1, the ground is bored and one vertical hole 4 is drilled, and a measuring pipe 6 having a through-hole strainer 5 on the side face is inserted and installed in the vertical hole 4. I do. The outer diameter of the pit 4 is such that the filter material or the waterproof material can be sufficiently filled between the pipe 6 and the hole wall.
(For example, pipe φ80mm,
Vertical hole φ150mm).

(2) Filter material and water-stopping material 7 (slow-acting granular bentonite, slow-acting water-absorbing rubber granules) are placed from the ground on the gap between the hole wall and the measuring pipe 6 based on the data at the time of boring. Etc.) in order. The position corresponding to the water-impermeable layers 2-12 and 2-23 is filled with the water-stopping material 7, and the flow of the groundwater between the hole wall and the measuring pipe 6 is stopped. The pipe at the position where the water blocking material 7 is filled is a side blind pipe 6 '. Further, a waterproof material may be filled between the pipe portion other than the strainer portion 5 and the hole wall.

(3) A groundwater flow direction / velocity meter including a thermal neutron detector 8 is attached to the rod 9 and inserted into the shaft 4. At this time, the water-stop packers 10 and 10 are attached above and below the detector 8. Thermal neutron detector 8
A neutron source, a thermal neutron detection tube, and a boron solution tracer injection hole, a tracer injection device provided on the ground,
The flow direction and velocity of groundwater are measured in combination with a digital count rate meter or the like (not shown).

As shown in FIG. 2, the water stopping packer 10 has a cylindrical shape and surrounds a rod 9 having a circular cross section. The water stopping packer 10 is partitioned by a partition 11 into concentric inner tank packers 10-1 and outer tank packers 10-2. Each of the inner and outer tank packers 10-1 and 10-2 is provided with a compressed air supply port 12, and a compressed air pipe is disposed between the inner and outer packers 10-1 and 10-2 and a packer operating device (not shown) installed on the ground. , Each expanded independently by the supply of compressed air,
Shrinks due to exhaust. That is, when the inner tank packer 10-1 receives the supply of the compressed air, it expands toward the rod 9 and closes the gap,
It is pressed against the surface of the rod 9. When the air is evacuated and contracted, it is separated from the surface of the rod 9 and the gap is opened. Similarly, when the outer tank packer 10-2 receives the supply of the compressed air, the measuring pipe 6
It expands to the side to close the gap and presses against the inner surface of the measuring pipe 6. When the air is evacuated and contracted, it is separated from the inner surface of the measuring pipe 6, and the gap is opened. Therefore, the inner tank packer 10
The following four states are created by a combination of the states of -1 and the outer tank packer 10-2.

(1) Inner tank packer 10-1, outer tank packer 10
-2 when both are expanding.

The rod 9 is fixed to the measuring pipe 6, and the gap between the rod 9 and the measuring pipe 6 is completely closed.

(2) Inner tank packer 10-1, outer tank packer 10
-2 when both are contracting.

The rod 9, the water stop packer 10, and the measuring pipe 6 are all movable relative to each other, and the gap between the rod 9 and the measuring pipe 6 is open.

(3) When the inner tank packer 10-1 is expanded and the outer tank packer 10-2 is contracted.

The rod 9 and the water stop packer 10 are fixed,
The rod 9 and the water stopping packer 10 can move inside the measuring pipe 6, the gap between the rod 9 and the water stopping packer 10 is closed, and the gap between the water stopping packer 10 and the measuring pipe 6 is open. .

(4) When the inner tank packer 10-1 contracts and the outer tank packer 10-2 expands.

The water stopping packer 10 is fixed to the measuring pipe 6, the rod 9 can move up and down in the water stopping packer 10, and the gap between the water stopping packer 10 and the measuring pipe 6 is a closed water stopping pack 10. The gap between the rod and the rod 9 is open.

(4) First, the flow direction and flow velocity of groundwater are measured for the second confined aquifer 1-2.

The detector 8 is attached to the rod 9, and the measuring rod 9 with the water stop packers 10, 10 attached above and below it is inserted into the measuring pipe 6. At the time of insertion, the inner tank packers 10-1 of the upper and lower waterproof packers 10 and 10 are expanded so that the rod 9 and the waterproof packer 10 are fixed. An upper and lower impermeable layer 2-12 in which the interval between the upper and lower waterproof packers 10 is upper and lower.
Is fixed so as to be the same as the distance between 2 and 23.
When the outer tank packers 10-2 of the upper and lower water stop packs 10 and 10 are expanded at the time when the predetermined depth is reached, the upper and lower water stop packs 10 and 10 become impermeable layers 2-12 and 2-12, respectively.
At the position 23, it is fixed to the measuring pipe 6, and the inside of the measuring pipe 6 is closed at the positions of the upper and lower impermeable layers 2-12 and 2-23. In this state, the flow direction and flow velocity of the groundwater are measured by the detector 8. The upper and lower waterproof packers 10 and 10 are contracted so that the measuring rod 9, that is, the detector 8 can be moved up and down.
Is moved again, the inner tank packers 10-1 of the upper and lower water stop packers 10 are again expanded to close the gap between the measurement rod 9 and the water stop packer 10, and the groundwater at that depth is closed. Is measured by the detector 8.

The shrinkage of the inner tank packer 10-1 and the detector 8
The vertical movement of the inner tank packer 10-1 and the measurement by the detector 8 are repeated several times according to the depth of the confined aquifer 1-2, and the Measure the direction and velocity of groundwater at each depth.

(5) Next, the flow direction and flow velocity of the groundwater are measured for the third confined aquifer 1-3.

The outer tank packers 10-2 of the upper and lower water stop packs 10, 10 are contracted so that the measuring rod 9 can move inside the measuring pipe 6. (Inner tank packer 10
-1 may be in any state of expansion and contraction, but is usually kept in the previous expansion state. ) The measuring rod 9 is moved downward, and the upper water-stop packer 10 is moved to the impermeable layer 2-2.
When reaching 3, the outer tank packer 1 of the upper waterproof packer 10
0-2 is expanded, and the upper water-stop packer 10 is impermeable layer 2-
At the position 23, it is fixed to the measuring pipe 6.

In this embodiment, the third confined aquifer 1-3 is the lowest confined aquifer, and there is no need to operate the water stop packer 10 below. Set aside. (If the third confined aquifer 1-3 is not the lowest confined aquifer, the inner tank packer 1 of the lower watertight packer 10 will be described.
0-1, the outer tank packer 10-2 is contracted, and the lower water stop packer 10 is moved to the position of the impermeable layer immediately below the confined aquifer 1-3. , Outer tank packer 1
0-2 are inflated, and the measuring rod 9 is
Is fixed to the measuring pipe 6. The flow direction and the flow velocity of the groundwater at each depth in the third confined aquifer 1-3 are measured by the same operation as the above (4).

(6) Finally, the flow direction and flow velocity of the groundwater are measured for the first confined aquifer 1-1. The measurement rod 9 is moved upward by the same operation as in the above (5), and when the lower waterproof packer 10 reaches the water-impermeable layer 2-12, the outer tank packer 10-2 of the lower waterproof packer 10-2. To fix the lower water-stop packer 10 to the measurement pipe 6 at the position of the water-impermeable layer 2-12. The first confined aquifer 1-1 is the uppermost confined aquifer, and it is not necessary to operate the upper water-stop packer 10, so that the first confined aquifer 1-1 is located at a position where it does not hinder the measurement as in (5) above. Set aside. The flow direction and flow velocity of the groundwater at each depth in the first confined aquifer 1-1 are measured by the same operation as the above (4).

With the above operation, the measurement of the flow direction and the flow velocity of the groundwater at every depth for all the confined aquifers using one measuring pipe 6 and one measuring rod 9 is completed. .

In this embodiment, for the sake of explanation of the operation of the upper and lower water-stopping packers, the measurement is performed in the order of second to third and first in the case of three layers of confined aquifer ground. As described above, the order of this measurement is the third-second-first order, and the first order.
-It may be the second to third order. Usually, measurements are taken in order from the lowest aquifer to the upper layer.

Instead of the thermal neutron detector in the above embodiment, a calorimetric or potentiometric groundwater flow direction / velocity meter can be used. Also in this case, the flow direction attached to the measuring rod,
A water stop packer is placed above and below the current meter to stop the vertical flow of groundwater, thereby making it possible to use one pipe for measurement,
Using the measurement rods, the flow direction and velocity of groundwater at each depth for all confined aquifers can be measured.

[0032]

The present invention is as described above. According to this measuring method, the flow direction and the flow velocity of the groundwater on the ground having a plurality of confined aquifers are determined by perforating a single vertical hole and one measuring pipe. , 1
Efficient measurement can be achieved by using a measuring rod.

The measuring rod, which is a measuring device, has water stopping packers disposed above and below the rod to which the groundwater flow direction / velocity meter is attached. The movable / fixed state can be freely selected by a combination of expansion and contraction of the tank packer, so that the upper and lower water stop packers can be accurately fixed to the upper and lower impermeable layer positions of each aquifer of multiple confined aquifers. Thus, the gap in the measuring pipe can be closed. Therefore, when measuring the flow direction and the flow velocity of the groundwater in each confined aquifer on the ground where a plurality of confined aquifers are present by using a single vertical hole and using one measuring pipe, Without having to lift it to the ground once,
Once the inserted measuring rod moves up and down and the inner tank packer,
Only the operation of expansion and contraction of the outer tank packer makes it possible to measure the depth of all the plurality of confined aquifers.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method of measuring the flow direction and flow velocity of groundwater according to an embodiment.

FIG. 2 is an enlarged sectional view of a water stop packer part of FIG.

[Explanation of symbols]

1 ... confined aquifer, 2 ... impermeable layer, 3 ... groundwater level, 4
…… Pit, 5… Strainer part, 6… Pipe for measurement,
6 ': blind pipe, 7: water stopping material, 8: thermal neutron detector, 9: measuring rod, 10: water stopping packer, 10-
1 ... inner tank packer, 10-2 ... outer tank packer, 11 ...
Partition wall, 12 ... Pressure air supply port.

Claims (2)

(57) [Claims] (A) drilling a pit in a confined aquifer ground in which a plurality of confined aquifers separated by an impermeable layer overlap;
A step of installing a measuring pipe having a strainer portion in the pit, and closing a gap between the pit at the position of the water-impermeable layer and the pipe by filling with a waterproof material; (B) groundwater flow direction / velocity meter Inserting a measuring rod in which a water stopping packer composed of a tank is mounted above and below the groundwater flow direction / velocity meter into the measuring pipe; (C) expanding the outer tank packings of the upper and lower water stopping packers; While fixing to the inner surface of the measuring pipe at the position of the impermeable layer above and below one aquifer to be measured, most of the gap between the measuring pipe and the rod is closed,
Due to the expansion and contraction of the inner tank packer of the upper and lower water stop packer, the rod is fixed at the time of expansion and the gap between the measuring pipe and the rod is completely closed, the rod can be moved up and down at the time of contraction, and the same band at the time of expansion Measuring the direction and velocity of the groundwater at each depth of the water layer; (D) shrinking the outer tank packer of the upper and lower water stop packers to release the fixation to the measurement pipe, and connecting the measurement rod to the next water supply; Moving to the layer position,
A method for measuring the direction and velocity of groundwater, comprising measuring the direction and velocity of groundwater in all aquifers by repeating the steps (C) and (D). 2. (A) A pit is drilled in a confined aquifer ground where a plurality of confined aquifers partitioned by an impermeable layer overlap and exist.
A measuring rod to be inserted into a measuring pipe having a strainer part in which the gap between the vertical hole at the position of the water-impermeable layer and the pipe is closed by filling with a waterproof material, and (B) a groundwater flow direction / velocity meter is attached. A watertight packer is disposed above and below the groundwater flow direction / velocity meter on the rod. The inner and outer tank packers are expanded or contracted by air pressure, respectively, and are capable of being pressed against or detached from the rod surface and the inner surface of the measurement pipe. measuring device.