JPH0627131A - Method and apparatus for measuring flow direction and flow velocity of underground water - Google Patents

Abstract

PURPOSE:To obtain the method and the apparatus, which can measure the flowing direction and the flow velocity of the underground water in the ground wherein a plurality of compressed water layers are present only by forming a vertical hole by using an underground- water flowing-direction/flow-velocity meter in a thermal neutron method, a heating-value method or a potential-difference method. CONSTITUTION:One vertical hole 4 is formed in the compressed water ground, wherein a plurality of compressed water layers 1 patitioned with impermeable layers 2 are overlapped and present. A measuring pipe 6 having a strainer part 5 is inserted into the vertical hole 4. The gap between the vertical hole 4 and the pipe 6 is filled and closed with water stopping materials 7 at the positions of the impermeable layers 7. The underground-water flow-direction/ flow-velocity meter of a thermo-neutron detector 8 is inserted into the pipe. A water stopping packer 10 has an inner tank packer and an outer tank packer, which are partitioned with a partioning wall that is expanded and contracted with air pressure. A rod 9, to which the water stopping packer 10 is attached, is inserted into the pipe. The inner and outer packers are expanded or contracted, and the gap in the pipe is closed. The flow of the underground water in the longitudinal direction is stopped. The detector 8 is moved and fixed at the specified measuring position. Thus, the flowing directions and the flow velocity of a plurality of compressed water layers 1 are measured.

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 a groundwater flow direction, a velocity meter groundwater flow direction and a flow velocity by a thermal neutron method, a calorimetric method or a potentiometric method.

[0002]

2. Description of the Related Art In construction work, including underground water,
It is necessary to measure the flow direction and velocity of groundwater for each stratum. As one means of this measuring method, Japanese Examined Patent Publication No. 60-27
A thermal neutron method using the thermal neutron detector proposed in No. 388 as a groundwater flow direction and velocity meter is known.

To measure with a thermal neutron detector, a vertical hole is drilled in the target ground, a measuring pipe equipped with a strainer is installed in the vertical hole, and the thermal neutron detector is inserted into this pipe. Then, a tracer having a large neutron absorption cross-section, for example, an aqueous solution of boron is fed to the periphery of the tracer.
Since the tracer flows under the control of the groundwater flow and is diluted, the concentration of the tracer can be measured by detecting the counting rate of thermal neutrons in each direction with a thermal neutron detector. You can know.

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

[0005]

However, in the ground under pressure, vertical groundwater flows in the vertical holes, which makes it difficult to measure the flow direction and flow velocity. When a plurality of confined aquifers overlap each other, it is necessary to perforate the measurement vertical holes to measure the number of confined aquifers. This requires a large space for survey measurements for a long period of time,
The cost is high.

The present invention has been made in view of the above problems. Even if the purpose is ground with multiple confined aquifers, it is suitable to use in a method that can accurately measure the flow direction and flow velocity of groundwater simply by drilling a single vertical hole, and this measurement method, etc. To propose a measuring device.

[0007]

A method for measuring the flow direction and flow velocity of groundwater according to claim 1 is a method for measuring the flow direction and flow velocity of groundwater by using a groundwater flow direction / velocimeter, and a plurality of layers are separated by an impermeable layer. A vertical hole is drilled in the confined aquifer where the confined aquifers overlap, and a measurement pipe with a strainer is installed in the vertical hole, and the gap between the vertical hole and the pipe at the impermeable layer position. Is filled with water-stopping material and blocked, and a rod with a groundwater flow direction / velocimeter and a water-stopper that expands or contracts due to air pressure is inserted into the pipe, and the water-stopper is expanded to expand the space between the pipe and the rod. Of the groundwater between the upper and lower confined aquifers, which are closed by the impermeable layer and block the gap, and measure the flow direction and flow velocity. Characterized by measuring the flow direction and velocity of the aquifer . The groundwater flow direction / velocity measuring device according to claim 3 is a ground pipe in which a measurement pipe equipped with a strainer is inserted into a vertical hole formed in the ground, and the groundwater flow direction / velocimeter is attached to the rod and inserted into the ground. In a device for measuring the flow direction and velocity of groundwater inside, a water stop packer is arranged on the rod above and / or below the ground water flow direction / velocity meter, and this water stop packer has a cylindrical shape. The inner and outer tank packers, which are concentric with each other, are partitioned by a partition wall, and the inner and outer tank packers are respectively expanded or contracted by air pressure so that they can be pressed into or released from the rod surface and the pipe inner surface. Is characterized by.

[0008]

EXAMPLE The ground to be measured in this example is shown in FIG.
As shown in, the first, second, and third confined aquifers 1-1,
1-2, 1-3 is a confined aquifer with overlapping layers,
The aquifers are separated by impermeable layers 2-12 and 2-23, and the aquifers 1-1, 1-2, 1-3 are groundwater layers 3-.
As for 1, 3-2 and 3-3, the lower layers are higher in order.

The flow direction and flow velocity of groundwater on this ground are measured by the following procedure. First, as shown in FIG. 1, the ground is bored to form a single vertical hole 4, and a measuring pipe 6 having a through-hole strainer portion 5 is inserted and installed in the vertical hole 4. The outer diameter of the vertical hole 4 is such that the filter material and the water blocking material can be sufficiently packed between the pipe 6 and the hole wall.
Larger than the outer diameter of the pipe (for example, pipe φ80 mm,
Vertical hole φ150 mm).

Next, at the positions corresponding to the impermeable layers 2-12 and 2-23, the gap between the hole wall and the pipe is filled with water blocking material 7 (bentonite or the like) to close the gap, and the gap between the hole wall and the pipe is closed. Stop the flow of groundwater. The pipe at the position where the waterproof material 7 is filled is a blind pipe 6 '. Further, a water blocking material may be filled between the hole wall and the pipe portion other than the strainer portion 5.

A groundwater flow direction / velocimeter composed of a thermal neutron detector 8 is attached to a rod 9 and inserted into the vertical hole 4.
At this time, the water blocking packer 1 should be placed above and below the detector 8.
Install 0 and 10. The thermal neutron detector 8 comprises a neutron source, a thermal neutron detector tube, and a boron aqueous solution tracer injection hole, and is combined with a tracer injection device, a digital count rate meter, etc. (not shown) provided on the ground, and the flow direction of groundwater, Measure the flow rate.

As shown in FIG. 2, the water blocking packer 10 surrounds a rod 9 having a cylindrical shape and a circular cross section, and is partitioned by a partition wall 11 into a concentric inner tank packer 10-1 and an outer tank packer 10-2. The inner and outer tank packers 10-1 and 10-2 each have a compressed air supply port 12, and a compressed air pipe is provided between the packer operating device (not shown) installed on the ground. , Contracts by being separately supplied with compressed air and expanded or decompressed. That is, the inner and outer tank packer 1
0-1 and 10-2 are inflated by the feeding of the compressed air to press the rod 9 surface and the inner surface of the pipe 6 respectively to close the gap, and at the same time, fix each other, discharge the compressed air and contract.
The rod 9 is detached from the surface of the rod 9 and the inner surface of the pipe 6 to open the gap between them, and at the same time, the mutual movement becomes possible.

When inserting the detector 8 into the vertical hole 4, the inner tank packer 10-1 is expanded to expand the rod 9 and the water blocking packer 10.
Is fixed. The fixing position is a position corresponding to the water blocking material 7 filled in the outer circumference of the pipe 6. After reaching the predetermined depth, the outer tank packer 10-2 is expanded to fix the pipe 6 and the water blocking packer 10 at the impermeable layers 2-12 and 2-23 positions filled with the water blocking material 7, Inner tank packer 10
-1 is contracted so that the rod 9, that is, the detector 8 is freely moved, and is moved to the measurement depth.

That is, when moving the rod, the water shut-off packer, and the flow direction / velocity meter body, the air in the outer tank packer is depressurized, the water shut-up packer is fixed to the measuring pipe, and the flow direction / velocity is varied depending on the depth. In order to obtain, the outer tank packer of the water blocking packer is pressurized and the air in the inner tank packer is depressurized.

When the measuring position of the detector 8 is determined, the outer tank packer 10-2 is left as it is and the inner tank packer 10-1 is expanded and brought into close contact with the rod 9 to close the gap. The gap between the hole wall and the pipe 6 is a water blocking material 7, and the pipe 6 and the rod 9
The gap between and is closed by the expanded inner and outer tank packers 10-1 and 10-2, respectively, and the vertical groundwater flow between the pressurized aquifers 1-1, 1-2, and 1-3 disappears. Water layer 1-2
It becomes possible to measure the flow direction and flow velocity of groundwater.

By repeating this operation, the flow direction and the flow velocity of the first or third pressure-bearing aquifers 1-1, 1-3 are measured using one vertical hole 4. In addition, in the case of measuring the first pressurized aquifer 1-1, the water blocking packer 10 attached at the upper position is unnecessary.

In place of the thermal neutron detector of the above embodiment, a calorimetric or potentiometric groundwater flow / velocimeter can be used. In this case as well, a water stop packer is installed at the flow direction attached to the rod, at the top and bottom of the current meter, or at one position to stop the vertical flow of groundwater and use a single pit to form multiple confined aquifers. The flow direction and flow velocity of can be measured.

[0018]

The present invention is as described above, and according to this measuring method, the flow direction and flow velocity of groundwater in the ground having a plurality of confined aquifers can be efficiently measured using a single vertical hole.

In this measuring device, the water blocking packer arranged above or below the rod on which the groundwater flow direction / velocimeter is attached closes or opens the gap between the pipe and the rod, and freely selects the groundwater measuring position. Since it can be fixed and stopped the vertical flow of groundwater,
It is suitable for measuring the flow direction and flow velocity of groundwater in the ground where a plurality of confined aquifers exist, with one vertical hole.

[Brief description of drawings]

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

FIG. 2 is an enlarged sectional view of a water blocking packer portion of FIG.

[Explanation of symbols]

1 ... Confined aquifer, 2 ... Impermeable layer, 3 ... Groundwater level, 4 ... Vertical hole, 5 ... Strainer part, 6 ... Measuring pipe, 6'blind pipe, 7 ... Water blocking material, 8 ... Thermal neutron Detector, 9 ... Rod, 1
0 ... Water-stopper packer, 10-1 ... Inner tank packer, 10-2 ... Outer tank packer, 11 ... Partition wall, 12 ... Pressure air supply port.

Claims (3)

[Claims] 1. The flow direction and flow velocity of groundwater are
It is a method of measuring using a current meter, and a pit is bored in the confined aquifer ground where a plurality of confined aquifers separated by impermeable layers overlap, and a strainer part is provided in this pit. A rod with a measuring pipe installed and a gap between the vertical hole and the pipe filled with a waterproof material at the impermeable layer position to block it, and a groundwater flow direction / velocimeter and a waterproof packing that expands or contracts by air pressure. Inserted into the pipe, expand the water stop packer to close the gap between the pipe and the rod, stop the flow of groundwater between the upper and lower pressurized aquifers separated by the impermeable layer, and measure the flow direction and velocity. A method for measuring groundwater flow direction and flow velocity, which comprises contracting a water-stopping packer and moving a rod in the vertical direction to measure the flow direction and flow velocity of a plurality of confined aquifers. 2. The groundwater flow direction and flow velocity measuring method according to claim 1, wherein a groundwater flow direction / velocity meter comprising a thermal neutron detector is used. 3. A measurement pipe equipped with a strainer is inserted into a vertical hole drilled in the ground, and a groundwater flow direction / velocity meter is attached to a rod in the pipe to measure the flow direction and velocity of groundwater in the ground. In this device, a water stop packer is arranged on the rod at one or both positions above and below the groundwater flow direction / velocimeter, and this water stop packer has a cylindrical shape and surrounds the rod to form a concentric inner tank. The packer and the outer tank packer are partitioned by a partition wall, and the inner and outer tank packers are expanded or contracted by air pressure, respectively, and can be pressed against the rod surface and the pipe inner surface, or can be detached freely. Flow velocity measuring device.