JPH0326454Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention measures the flow direction and velocity of groundwater by drilling a deep hole in the ground and suspending a measuring device into the hole when conducting a ground survey. This article relates to a device for measuring flow direction and velocity in a hole using a laser.

[Prior Art] To measure the flow direction and velocity of groundwater, first, a deep hole is drilled into a predetermined ground using a poling machine. Next, a Yagura is installed above the excavated hole, a measuring device for measuring the flow direction and velocity inside the hole is attached to this Yagura, and this measuring device is suspended to a predetermined location in the hole where the measurement is to be made. The measuring device lowered into the hole is fixed in the formation to be measured. When the measuring device is fixed, groundwater flowing within the formation passes through the measuring device. By detecting groundwater passing through the measuring device with a sensor probe, it is possible to measure the flow direction and velocity of groundwater at the measurement point on the ground.

BACKGROUND ART Conventionally, as a measuring device for measuring the flow direction and flow velocity of groundwater in a hole of this type, the following configuration is known. This measuring device has a sensor probe in the middle that is a measuring part for measuring the flow direction and flow velocity at a predetermined location in the hole, and an upper packer that is a fixing mechanism installed at the lower part via a rod. It is connected to the lower part car. moreover,
A tracer whose concentration changes depending on the flow of groundwater (for example, saline, distilled water, boron, etc. is used) is introduced into the sensor probe, and a tracer is used to measure the change in concentration. It has a built-in sensor. In addition, the upper and lower packers are rubber balloon-shaped items made of hard rubber, which are inflated by compressed air sent from the ground and fixed by being pressed against the wall inside the hole.Furthermore, the middle The structure is such that it also fixes the sensor probe.

[Problem that the invention attempts to solve]

However, the above-mentioned conventional in-hole flow direction/velocity measurement device using a tracer has the following drawbacks.

(1) The true flow velocity in the borehole cannot be directly measured because the flow velocity in the borehole is indirectly determined by detecting changes in the concentration of the tracer with a sensor.

(2) Measurement takes time because a tracer is injected.

(3) The measurement range of flow velocity is limited because it is measured using a tracer.

(4) As the temperature and pressure of groundwater change due to the installation of sensor probes, changes occur in the flow of groundwater, but since this cannot be measured, changes in flow cannot be checked.

(5) Since the tracer is injected into the measurement area, changes in the temperature and density of groundwater or diffusion phenomena occur, causing a flow different from the original flow of groundwater in the hole.

This idea was made in view of the above circumstances, and it is important to understand the true flow direction and direction of groundwater, which has a wide range of flow velocities.
The object of the present invention is to provide a flow direction/velocity measuring device in a hole that can instantaneously and directly measure flow velocity and check the influence of installing the measuring device in the hole on the flow of groundwater.

[Means for solving problems]

This idea involves drilling a deep hole in the ground, installing a sensor probe as a measuring part in the hole, and fixing the sensor probe at a predetermined location in the hole through rods at both ends of the sensor probe. An in-hole flow direction/flow velocity measuring device is provided with an upper parter and a lower parter to measure the flow direction and flow velocity of groundwater flowing in the hole, and the sensor probe is provided with a flow path through which groundwater in the hole can flow. A laser photon current meter capable of measuring the flow velocity of groundwater in this channel is provided, and the laser photon current meter is arranged and fixed so that each laser beam forms interference fringes within the channel. a plurality of light emitting parts;
The present invention is characterized in that a light receiving section is provided to receive scattered light from the flow path, and the laser photon current meter is further provided with a temperature/pressure sensor that measures the temperature and water pressure within the flow path.

〔Example〕

This invention will be explained below with reference to FIGS. 1 to 6. FIG. 1 is an explanatory diagram for explaining the entirety of this invention, and reference numeral A indicates the ground to be investigated. A ₁ is an impermeable layer, A ₂ is an aquifer through which groundwater flows, and H is a deep hole drilled into this ground A. B is the measurement section for measuring the flow of groundwater, and M is the Yagura section built above ground. K is a cable attached to the Yagura section M, and P is a flow direction/flow velocity measurement device (hereinafter simply referred to as "measuring device") in the hole attached to the tip of the cable K.

FIG. 2 is a diagram showing the Yagura part M installed on the ground, and reference numeral _M1 is the Yagura main body. M ₂ is a cable winding device, to which a compressed air supply section M ₃ and a measured value receiving section M ₄ are connected, and a part of the laser photon current meter is connected to the cable winding device M ₂ . The formed laser source section _M5 and photon receiving section _M6 are connected by optical fibers _K4 , _K4 , and _K5, respectively. Additionally, compressed air supply M ₃
consists of an air compressor _M7 and a control device _M8 that adjusts the pressure of the compressed air supplied from it, and the photon receiver _M6 consists of a photon detector _M9 and a digital correlator _M10 . . In addition, the cable K is wound around the cable winding device _M2 , and the cable K is connected to the Yagura main unit.
It is hung on a pulley _M11 attached to the top of _M1 . A measuring device P is attached to the tip of a cable K that is hung around a pulley _M11 .

Next, FIG. 3 is a diagram showing the measuring device P, in which reference numeral 1 is a sensor probe. One end of the upper rod 2, 2 which is connected in series and whose length is adjustable is fixed to the upper part of the sensor probe 1, and a hollow cylindrical rod made of hard rubber is fixed to the other end of the upper rod 2, 2. The upper part car 3 is attached. A connector 4 is fixed to the upper part of the upper packer 3, and a cable K is further attached to the upper part via the connector 4. On the other hand, one end of lower rods 5, 5, which are connected in series and whose length can be adjusted, is fixed to the lower part of the sensor probe 1, and the other end of the lower rods 5, 5 is fixed with a hollow made of hard rubber. A cylindrical lower part car 6 is attached. Further, between the sensor probe 1 and the upper packer 3, a measurement value transmission cable _K1 is spirally wound around the upper rods 2, 2 located therebetween. Furthermore, inside the upper rods 2, 2, there is an air supply tube _K3 to the lower packer 6, and three optical fibers _K4 ,
K ₄ and K ₅ communicate with each other, and an air supply tube K ₃ for supplying air to the lower packer 6 communicates inside the lower rods 5 and 5 .

FIG. 4 is a diagram showing a cross section of the cable K, which includes an electric transmission cable K ₁ for transmitting measured values by the sensor probe 1, and an air supply tube K for supplying air to the upper pump car 3. ₂ and
Air supply tube K ₃ for supplying air to the lower part car 6 and two light emitting optical fibers K ₄ , K ₄
and a light-receiving fiber _K5 sandwiched between them.

FIG. 5 is a diagram showing a cylindrical sensor probe 1, and reference numeral 8 is a cylindrical body located at one end of the sensor probe and incorporating a multi-braking digital signal transmitting amplifier and a direction indicator/direction control device. The cylindrical body 8 has a built-in light emitting part which is the exit of the laser that is emitted from the laser source _M5 and passes through the optical fibers _K4 and _K4 , and a light receiving part that receives the reflected light of the laser emitted from the light emitting part. The cylindrical bodies 9 are connected. Further, the other end of the sensor probe 1 is provided with a connector 10 for connection to the lower rod 5 and a mirror portion 10a fixed to the connector 10. A cylindrical support basket 11 made of stainless steel is attached between the cylindrical body 9 and the connector part 10. Therefore, the inside of this support cage 11 is a flow path through which the groundwater in the hole H can flow. Inside the support cage 11, a temperature measurement sensor 15 whose one end is fixed to the cylindrical body 9 and a pressure measurement sensor 16 are provided. Further, the cable K continues into the support cage 11. An air supply tube K ₃ to the lower pack car 6 is provided. FIG. 6 is a sectional view taken along the line X--X in FIG. 5.

In order to measure the flow direction and velocity of groundwater using the measuring device P configured as described above, first, as shown in Figure 1, the ground layer A ₂ to be measured,
A hole H reaching A ₂ ... is excavated with an excavator (not shown).

Next, the measuring device P is suspended from the Yagura main body _M1 into the excavated hole H via the cable K wound around the winding device _M2 . Hanging measuring device P
When reaches the measuring section B, the winding device _M2 is stopped and the measuring device P is stopped at a predetermined position. When the measuring device P stops at a predetermined position, the air pressure is adjusted from the compressed air supply section _M3 on the ground, and the air is passed through the air supply tube _K2 in the cable K to the upper compressor car 3.
Compressed air is supplied to. When compressed air is supplied, the upper packer 3 expands and presses against the wall surface of the hole H, becoming immovable and fixed in that position. Similarly, when compressed air is supplied from the compressed air supply M ₃ to the lower packer 6 through the air supply tube K ₃ in the cable K, the lower packer 6 is expanded and fixed in its position. By expanding and fixing the upper and lower packers 3 and 6 in this manner, the sensor probe 1 located in the middle thereof is also fixed in that position.

Next, when the sensor probe 1 is fixed in the measurement section B, the pressure measurement sensor 16 measures the pressure change in the flow path to measure the pressure change in this measurement section B, and at the same time the temperature By measuring the pressure change in the flow path with the measurement sensor 15, the temperature change in the measurement section B is measured. When the flow of groundwater in measurement section B settles down and the flow reaches a steady state, the measured temperature and pressure settle down to constant values. Once the measured value has settled down, the orientation of the measuring device P is measured and confirmed using a direction meter built into the cylindrical body 8. The measured values of water temperature, water pressure, and direction are digitized by multiplexing in the cylindrical body 8, and are electrically transmitted to the measured value receiving section _M4 on the ground through the single wire covered electric transmission cable _K1 in the cable K. Record there
Parsed.

When the flow of groundwater passing through the sensor probe reaches a steady state, a laser beam is emitted from the laser source _M5 on the ground. The emitted laser passes through optical fibers K ₄ , K ₄ in the cable K and reaches the light emitting section built in the cylindrical body 9 . The two laser beams that have reached the light emitting section are emitted from there toward the center of the sensor probe, that is, toward the groundwater flowing in the flow path. The two emitted laser beams intersect within the flow path of the sensor probe, generating interference fringes. Scattered light is generated when particles in groundwater pass through the generated interference fringes. The generated scattered light reaches the light receiving section built into the cylindrical body 9 either directly or by being reflected by the mirror section 10a. The scattered light (photons) reaching the light receiving section travels through the optical fiber _K5 in the cable K and reaches the photon receiving section _M6 on the ground. The scattered light (photons) reaching the photon receiver _M6 is detected by a photon detector _M9 and converted into an electrical signal. The converted electrical signal is sent to the digital collector M ₁₀ for analysis and recording. In this way, the flow rate of groundwater can be determined. This laser photon current meter is an LDV (Laser Doppler Velocimeter) that uses optical fiber.
It uses the principle of

Here, the operating principle of LDV will be explained. A laser beam emitted from a laser source is split into two beams of equal intensity, and a lens is used to make them intersect at one point. In this intersection region (measurement point), interference fringes are generated with intervals determined by the wavelength λ of the laser light and the intersection angle θ. The spacing of this interference fringe
dF is expressed as dF=λ/2sin(θ/2). When a fine particle (with a diameter of several μm) passes through this measurement point, the intensity of the light scattered by the particle is strong when the particle is in the bright part of the interference pattern, and becomes weak when the particle is in the dark part. The change is proportional to the moving speed of the particle and inversely proportional to the spacing of the interference fringes. The moving speed of particles can be measured by focusing this scattered light with a lens, converting it into an electrical signal with a photoelectric converter, and measuring the period td or frequency fd of the signal (Doppler signal). Now, if we consider the case where a particle passes perpendicularly to the plane of interference at a velocity V, V is V=
It is expressed as dF/td=dF・fd=(λ/2sin(θ/2))・fd. This only measures the velocity of the particles, not the velocity of the fluid. However, if small enough particles are used, the particles will follow the fluid, making it possible to measure the flow velocity.

Based on the above principle, by measuring the temperature and pressure of the groundwater in the measurement section B with the temperature measurement sensor 15 and the pressure measurement sensor 16, it is confirmed that the flow has reached a steady state, and the state of the flow is determined. By measuring with a laser, the true groundwater flow velocity can be directly measured. When the measurement in one direction is completed in this manner, the sensor probe is rotated by 90 degrees using the direction control device built into the cylinder 8, thereby making it possible to measure the flow velocity in the direction perpendicular to the measurement direction. Furthermore, when the measurement in this measurement section B is completed, the air is removed from the upper and lower packers 3 and 6, and the measurement device P is moved to the depth of the next measurement section and the measurement is repeated.

In this way, since the temperature, pressure, flow direction, and flow velocity of the groundwater are measured by the measuring device P, the true flow direction and flow velocity of the groundwater in the hole H can be directly measured, and the measurement time can be shortened. The measurement range of flow velocity is V=1×10 ⁻⁶ cm/sec to V=5×10 ⁴ cm/sec, and a wide range of measurement is possible. Furthermore, the measuring device P
Since it is possible to check the transient flow caused by the installation of the system, it is possible to always measure the flow velocity in a steady state. Furthermore, the structure of the sensor probe 1 hardly affects the groundwater by density changes or diffusion phenomena. Furthermore, this measuring device P can check the pressure of the upper and lower packers 3 and 6 using the pressure sensor 16.

Next, a second embodiment of this invention will be described using FIG. 7. This example is an example in which a sensor probe as shown below is applied to the measuring device P of the first example. In FIG. 7, reference numeral 20 denotes a sensor probe, and the same components as those of the sensor probe 1 of the above embodiment are given the same reference numerals, and their explanations will be omitted. This sensor probe 20 measures the flow velocity of the fluid by receiving backscattered light obtained by irradiating laser light onto particles in the fluid passing through the measurement point.
This eliminates the need for the mirror section 10a used in the previous embodiment. Therefore, inside the cylindrical body 9, there are two light-emitting optical fibers 21, 21 that emit laser light.
and a light-receiving optical fiber 22 that receives backscattered light.
are integrated and fixed so that adjustment of the optical axis is not necessary. Moreover, the light emitting optical fiber 21,
A condenser lens 23 is fixed in front of the light-receiving optical fiber 21 and the light-receiving optical fiber 22, and a light-receiving lens 24 for backscattered light is provided between the condenser lens 23 and the light-receiving optical fiber 22. The tip of the light-receiving optical fiber 22 is set at the focal point of the light-receiving lens 24, and the backscattered light efficiently enters the light-receiving optical fiber 24 through the action of the focusing lens 23 and the light-receiving lens 24. It is constructed to emit light. Therefore, the sensor probe 20
The length of the sensor probe (the length of the support basket 11 portion of the sensor probe 1) is shorter than that of the sensor probe 1 of the above embodiment. The other configurations are the same as those of the above embodiment.

Next, the operation of this sensor probe 20 will be explained.

When the flow of groundwater passing through the sensor probe 20 reaches a steady state, the laser source on the ground
A laser is emitted from _M5 . The emitted laser beam is transmitted through the optical fibers K ₄ and K ₄ in the cable K to the two light emitting optical fibers 2 built into the cylindrical body 9.
It is ejected from 1,21. The two emitted laser beams are focused by a condenser lens 23 on a measurement point S shown in FIG. 7, and interference fringes are generated there. When particles in groundwater pass through the generated interference fringes, backscattered light is generated. The generated backscattered light is collected by a condenser lens 23 and a light receiving lens 24,
The light is guided to the light receiving optical fiber 22. The backscattered light guided to the light-receiving optical fiber 22 travels through the optical fiber _K5 in the cable K and reaches the ground, where it is converted into an electrical signal and analyzed and recorded.

Here, as mentioned above, the sensor probe 2
The light-emitting optical fibers 21, 21 and the light-receiving optical fiber 22 in 0 are integrally fixed, and in front of them, a condensing lens 23 and a light-receiving lens 24 are connected to the optical fibers 21, 21, 22. Since it is set at an appropriate focal length of 22,
This sensor probe 20 does not require adjustment of the optical axis every time a measurement is made. In addition, since it is configured to measure backscattered light, a signal can be obtained as long as the length of the sensor probe 20 is long enough from the laser light emitting part to the measurement point S. It is possible to shorten the measurement time and also to shorten the measurement time. Other functions and effects are the same as those of the first embodiment.

[Effect of idea]

As mentioned above, this idea provides a sensor probe with a flow path through which groundwater can flow, and is also equipped with a laser photon current meter and a temperature/pressure sensor that can measure the flow velocity of groundwater in this flow path. , the laser photon current meter includes a plurality of light emitting sections arranged and fixed so that each other's laser beams form interference fringes within the flow channel, and a light receiving section that receives scattered light from the flow channel. By providing this, the following effects can be obtained.

(1) The true flow velocity of groundwater inside the hole can be directly measured.

(2) Measurement time can be shortened.

(3) Flow velocity measurement range is V=1×10 ^-6 cm/sec ~ 5
It is possible to measure a wide range of ×10 ⁴ cm/sec.

(4) As the temperature and pressure of the groundwater changes due to the installation of the sensor probe, changes will occur in the flow of groundwater, but since the temperature and pressure sensor can constantly check the pressure and temperature changes in the flow path, It is possible to measure the flow direction and velocity in steady state. Moreover, since the water pressure in the flow path is monitored by a pressure sensor, it is possible to check the level of pressure in the flow path due to the increase in water pressure in the flow path due to the expansion of the upper and lower packers, and also to check the condition of the measurement section based on the subsequent attenuation of water pressure. Water permeability can be estimated.

(5) Since a tracer is not used in the sensor probe, there are almost no density changes or diffusion phenomena in the groundwater being measured.

(6) Moreover, this measuring device can be made smaller in diameter than conventional measuring devices, so it can be applied to deep holes with smaller diameters.

(7) The light-emitting part and the light-receiving part are fixed and placed in the sensor probe in advance, making it possible to perform simple and quick measurements without the need for fine adjustments that are typical of optical systems.

[Brief explanation of drawings]

Figures 1 to 6 are diagrams showing embodiments of this invention. Figure 1 is an explanatory diagram for explaining the whole of this invention, Figure 2 is a front view showing the Yagura section, and Figure 3 is a front view showing the Yagura section.
The figure is a front view of the measuring device, Figure 4 is a cross-sectional view of the cable, Figure 5 is a perspective view of the sensor probe, Figure 6 is a cross-sectional view taken along the line X-X of Figure 5, and Figure 7 is backscattered light. FIG. 2 is an explanatory diagram for explaining a sensor probe that measures . A...Ground, H...Hole, _M5 ...Laser source section, _M6 ...Photon receiving section, 1, 20...Sensor probe, 2...Upper rod, 3...Upper guard, 5... Lower rod, 6... lower part car,
9...Cylindrical body with built-in light emitting part/light receiving part, 15...Temperature measurement sensor, 16...Pressure measurement sensor.

Claims (1)

[Scope of utility model registration request] A deep hole is drilled in the ground, and inside the hole there is a sensor probe which is a measuring part, and an upper and lower part are attached to both ends of the sensor probe to fix the sensor probe in a predetermined place in the hole via rods. An in-hole flow direction/flow velocity measuring device for measuring the flow direction/flow velocity of groundwater flowing in the borehole, wherein the sensor probe is provided with a flow path through which the groundwater in the borehole can flow, and the flow channel A laser photon current meter capable of measuring the flow velocity of groundwater in the flow path is installed, and the laser photon current meter has a plurality of light emitting lights arranged and fixed so that each other's laser beams form interference fringes within the flow path. and a light-receiving section that receives scattered light from the flow path, and the laser photon current meter is further provided with a temperature/pressure sensor that measures the temperature and water pressure in the flow path. A device for measuring flow direction and velocity inside a hole using a laser.