JP2002116265A - Method and system for measuring underground or underwater physical or chemical characteristics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the labor and personnel for moving sensors for changing measurement depth or the like and for making repeated measuring. SOLUTION: A plurality of characteristics-detecting sensors are connected to one signal cable 11-15 via a predetermined space, and suspended and set to each of a plurality of points or boreholes B1-B6 bored in a measurement object region. A control means for applying measurement orders sequentially and synchronously via the signal cables 11-15 are set to the sensor group set to each borehole, and a data-collecting means for collecting measured data sequentially outputted from each sensor via the signal cables 11-15, and in this way, a system for measuring underground or underwater physical or chemical characteristics is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a system for measuring physical or chemical properties underground or in the sea at a number of points in a horizontal direction and a depth direction at the same time.

[0002]

2. Description of the Related Art It is possible to know the geology and ground condition by measuring the electrical conductivity at several points in the ground, comprehensively considering the measured values, and observing the temporal changes in the measured values. . In addition, by observing the temperature distribution in the sea and its temporal change, it is possible to know the state of the sea and the influence of maritime phenomena. Techniques for investigating, exploring, and diagnosing the physical and chemical properties of underground, underwater, freshwater, and brackish water are used in a wide range of fields, including environmental protection, disaster prediction and prevention, civil engineering, and construction.

As an example, as a method of measuring the electrical conductivity of groundwater, a cable (or wire) having an electrical conductivity sensor attached to the tip is dropped into an observation hole or a boring hole opened from the surface of the ground and dropped to a depth to be measured. Methods for measuring are known. In order to measure at several points in the depth direction, a method is adopted in which the cable is sequentially lowered into the hole and the sensor is moved to change the depth.

[0004]

Problems with this method are as follows. (1) Groundwater, which is a medium to be measured by suspending a sensor, is disturbed, and accurate measurement cannot be performed.
(2) In order to obtain several data points in the depth direction, the sensor must be moved to the next depth after the measurement at a certain depth (one point) is completed. , Measurement data for each point cannot be obtained simultaneously,
(3) Changing the measurement depth or constantly requiring an operator to perform repeated measurements.

To solve the above problems (2) and (3), a method has been proposed in which several cables with sensors are bundled, inserted into a hole, and suspended at a depth to be measured. As the number of signal lines increases and the number of sensors that can be inserted into the hole is restricted, the number of measuring devices installed on the ground also increases, complicating measurement, and depending on the diameter of the hole, practically, The limit is about 10 sensors.

The present invention has been made in view of the above points, and has no limitation on the number of sensors, is not affected by disturbance of a measurement medium, and has a small number of workers involved in a measurement operation. It is an object of the present invention to provide a measurement method and a system that can collect data at several points simultaneously.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method in which a plurality of characteristic detection sensors are separated by a predetermined distance at each of a plurality of points in a measurement target area. It is connected to a signal cable and suspended, and gives a measurement command to the plurality of sensors at each point sequentially and synchronously via the signal cable, and collects measurement data sequentially output by each sensor via the signal cable. To measure physical or chemical properties underground or in the sea.

Further, according to the present invention, a plurality of characteristic detection sensors are spaced apart from each other by a predetermined distance in each of a plurality of boring holes drilled in a measurement target area, connected to a single signal cable, and suspended. Control means for sequentially giving a measurement command to the sensor group arranged in each boring hole via the signal cable, and data collection means for collecting measurement data sequentially output by each sensor via the signal cable. And constructed a system for measuring physical or chemical properties in the ground or in the sea.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, a system for measuring the electric conductivity of groundwater will be described as an example.

FIG. 1 is a conceptual diagram of a system for measuring the electric conductivity of groundwater according to the present invention. Predetermined measurement target area
A plurality (for example, six) of data measurement boring holes B1 to B6 are formed in R. Boring holes B1, B2,
B3, B4 and B6 are drilled in the vertical direction at a depth of, for example, about 150 m, while the boring hole B5 is inclined with respect to the horizontal plane. The boring hole B7 is not a hole for data measurement, but is a hole that is bored vertically for intentionally flowing, for example, salt water, which is a high electrical conductivity medium, in order to obtain a measurement result convenient for later analysis or evaluation. This boring hole B7 is, for example, the nearest boring hole B
For example, a hole is drilled at a distance of, for example, several tens of meters from 4.

In the boring holes B1 to B6, cables 11, 12, 13, 14, 15 in which 20 sensors are electrically and mechanically connected at 1m intervals are suspended vertically or inclined from the ground.

FIG. 2 shows a connection state between the electric conductivity sensor and the cable.

The uppermost electric conductivity sensor S1-1 is connected to the suspension cable 60 via a hanger H, and the sensors (for example, the sensors S1-1 and S2-2) are mechanically made of two aluminum sheets. A cable 62 whose length is electrically connected to the outside of the sensor by a hanging plate 61 and whose distance between the electrodes of the sensor is 1 m is connected by connectors 63 at both ends of the sensor. The connector 63 has six pins, has a double O (O) ring inside, and a connector on the cable side and a connector on the sensor side are screw-fitted in a liquid-tight manner. Cable 62
Are two wires for supplying power (DC), two wires for transmitting measured analog data, one wire for transmitting digital clock that determines measurement timing, and a sensor for transmitting analog data. It is composed of a six-core cable composed of a total of six conductors of one wire for a carrier signal for switching, and the whole is covered with a corrosion-resistant insulating material such as urethane resin. Under the lowermost sensor S1-20, a stainless steel weight W of 2 to 3 kg is attached to the suspension plate 61.
Attached to. Cable length is 5 depending on the application
A different length such as 10 m or 10 m is prepared in advance.

The electric conductivity sensor is, as shown in FIG.
Both ends of a urethane-based hard rubber cylindrical sleeve 70 are covered with stainless steel caps. Inside the sleeve 70, a shift register described later, a sensor amplifier, and an electronic circuit board on which a switch is mounted are incorporated. Is sealed with a resin, and a sleeve 70 is provided near the lower end of the sleeve 70.
Is provided with a hole 70a penetrating at right angles to the longitudinal axis thereof, and four electrodes 53 (in FIG. 4, the whole is shown as 53 (1), 53 (2),. Is provided so as to be exposed. Further, inside the sleeve 70, a temperature sensor for detecting the temperature in the vicinity of the electrode 53 for converting the measured electric conductivity into a value at a standard temperature (25 ° C.) is incorporated.
Outside the sensor, as shown in FIG.
A centerizer 71 made of aluminum is mounted at a position slightly shifted from the surface by 0 degrees. This, in combination with the suspension plate 61, functions so that the sensor is located substantially at the center of the boring hole when the sensor group is inserted into the boring hole.

The electric conductivity sensor shown in the drawings measures the potential difference of the electric field in the medium generated by one pair of current electrodes when the medium is inserted into the medium, and measures the electric conductivity of the medium as a function of this electric potential. It is a four-electrode type that calculates the degree,
In addition, an electromagnetic induction type sensor can be used.

FIG. 4 is a block diagram showing an electric circuit of the electric conductivity sensor shown in FIG.

Since each sensor has the same circuit configuration, the sensor S1-1 will be described.
(1), a sensor amplifier 51 (1) for amplifying a voltage for detecting a pair of potential differences among the four electrodes 53, and a switch 52 (1) connected to an output terminal of the sensor amplifier 51 (1).
When the clock terminal CL of the shift register 50 (1) is connected to a clock transmission wire, a clock signal is supplied, and a carrier signal is supplied to the input terminal IN (1), the output terminal OUT (1) The switch 52 (1) is turned on by a signal output from the switch. When the switch 52 (1) is turned on, analog data from the sensor amplifier 51 (1) is taken out via a data transmission wire.

Referring again to FIG. 1, a clock signal and a carrier signal serving as a measurement start command are transmitted to the sensors arranged in the boreholes B1 to B6 on the ground in the vicinity of the boreholes B1 to B6, and output from the sensors. Conversion of the analog measurement data to a digital signal
Are provided with data transmitters 21 to 26 for transmitting to the signal control unit 30 installed in the communication device.

The measurement center 100 is temporarily installed near the measurement site, and includes a signal control unit 30 for controlling a measurement operation by a group of electric conductivity sensors arranged in six boring holes. A data input board 31 for an operator to set measurement conditions, and data transmitters 21 to 21
26, a data recording unit 32 having a storage unit for storing measurement data transmitted from 26, a data display unit 33 for recording or displaying measurement results in a desired format, and a power supply unit 34 for supplying power to the measurement system and sensors. Is installed. The signal control unit 30 and the data input board 31 can be constituted by a personal computer, the data display unit 32 is constituted by a printer and a display, and the measurement results can be confirmed on the spot.

FIG. 5 shows a block diagram of an electric circuit of the entire measurement system, and the same reference numerals as those in FIG. 1 indicate the same components. For example, 2 disposed in the boring hole B1
The zero electrical conductivity sensors are S1-1, S1-2, S1
-3,... S1-20. When the boring hole is located away from the measurement center 100 (see FIG. 1),
An intermediate connection box that can relay data obtained from the sensor can be provided on the way.

Next, the measurement of electric conductivity in the present embodiment will be described with reference to FIGS.

Prior to the measurement, the operator has
At 0, measurement conditions (for example, a measurement start instruction, a measurement start time, a data acquisition interval, etc.) are input from the data input board 31.

When a measurement start command is input from the data input board 31, a measurement start command is output from the signal control unit 30 at set intervals, and the data transmitters 21 to 26 are output.
Simultaneously output only one wave of clock signals of the number of suspended sensors and a carrier signal having a width twice as large as the clock signal. For easy understanding, a description will be given of a measurement operation by a series of sensors (for example, measurement at the boring hole B1) with reference to FIG. 4. The shift register 50 (1) of the uppermost sensor S1-1 has a clock terminal. When a clock signal is received by CL and a carrier signal is received by the input terminal IN (1), the switch 52 (1) is turned on by the ON signal output from the OUT (1) terminal by the pulse width of the carrier signal. Turn off. While the switch 52 (1) is ON, the data of the electric conductivity amplified by the sensor amplifier 51 (1) is transmitted to the data transmitter 2 via the data transmission wire.
It is sucked up by 1.

OUT (1) of shift register 50 (1)
When the output of the terminal is turned off, the second sensor S1-
An ON signal is output from the OUT (2) terminal of the second shift register 50 (2), and the switch 52 (2) is turned on for a certain period of time and then turned off. Therefore, during this time, the second sensor S1
The data of the electric conductivity measured by -2 is collected. Thereafter, this operation is sequentially repeated for the third sensor, the fourth sensor,..., And the twentieth sensor S1-
The process proceeds to 20, and a total of 20 pieces of electric conductivity data are sequentially extracted. The same applies to the other five series.

When the same number of clock signals as the number of sensors are transmitted from each data transmitter for all the series, signals (analog voltages) from all the sensors are electrically disconnected, and one measurement is completed.

The data obtained in each stream is converted into digital signals by the data transmitters 21 to 26,
The signal is transmitted to the signal control unit 30 by the transmission method of S-422. If a data transmission method based on RS-422 is adopted, data transmission from a point separated by several km or more is possible. The signal control unit 30 puts the obtained six series of electrical conductivity data into a predetermined format and complies with the standard RS-
The data is transmitted to the data recording unit 32 by the transmission method of 232C. In the data recording unit 32, data is stored in a memory.

The recorded data undergoes necessary processing including temperature correction, is recorded in another memory, and is displayed on the data display unit 33 in a desired form by setting from the data input board 31 or by setting in advance. can do. This display can be switched manually or automatically, and printing can be performed if necessary.

In this embodiment, there is the convenience that all measurement operations and data can be managed by the control unit and the data recording unit provided in the measurement center.

FIG. 7 is a chart for about 90 seconds in which a change in electric conductivity with time is recorded every 10 seconds for 20 sensors suspended in one boring hole (1).
, 2ch, 3ch, ... are the first, second, third, ... sensors from the top of the borehole.) The vertical axis of the figure indicates the sensors 1 to 20 ch, and the horizontal axis indicates the elapsed time (unit: second).

As can be seen from the figure, the outputs of all the sensors are almost the same 90 seconds before (the rightmost side in the figure), but gradually from about 70 seconds ago, 12 channels to 16
The output of the sensor of the channel starts to become larger than the output of the other sensors, the tendency lasts for 30 to 40 seconds, and the difference becomes more and more about 30 seconds before, and about 10 seconds ago, the output of the 15ch and 16ch sensors becomes smaller. The output prominently prominent,
At this point (0 on the horizontal axis), it can be clearly seen that the tendency changes to a slightly different one.

FIG. 8 also shows the temporal change of the electric conductivity detected by one boring hole sensor (in this case, ten sensors 1ch to 10ch are used in order to avoid overlapping and difficulties in viewing). Is a graph created by plotting. The vertical axis of the graph indicates electrical conductivity (relative), and the horizontal axis indicates elapsed time (unit: time).

When the measurement is started and a certain time (for example, 10 hours) has elapsed, a salt water, which is a high electric conductivity medium, is injected from the borehole B7, and a change in electric conductivity is observed.

FIG. 3 shows the change in the electric conductivity after the salt water was injected into the borehole B7, and the state of diffusion of the salt water can be understood very well. In the figure, 9 ch and 10 ch
Since the change in the electric conductivity of the sensor of the channel is smaller than that of the other sensors, it can be estimated that the geology existing at the depth where the sensors of the 9ch and 10ch are arranged is in a different hydraulic condition from the other places.

In the present embodiment, the measurement accuracy and the measurement range required for the measurement are as follows. (1) Measurement accuracy required for measurement The measurement resolution of the electric conductivity sensor of this device is 1 μS / cm
(Micro Siemens). For reference, the natural change in the electrical conductivity of natural groundwater is several tens μS / cm to several hundreds.
μS / cm. (2) Measurement range required for measurement The measurement range of the electric conductivity sensor of the present device is 1 μS / cm to 50,000 μS / cm. For reference, the natural change in the electrical conductivity of natural groundwater is several tens μS / cm to several hundreds.
μS / cm, and the average electric conductivity of seawater is 32000.
μS / cm.

Although the number of sensors used in the present invention is not limited in principle to the number of cables, the number of sensors according to the system is determined in consideration of fluctuations in the analog voltage output from the sensors and restrictions on the measurement time. Can be

In the above embodiment, the case where the present invention is applied to the measurement of the electric conductivity of groundwater has been described as an example. However, the present invention measures the presence or absence of a specific gas or chemical substance in the ground and the concentration thereof, It can be applied to the investigation of the condition of underground rock, the measurement of the temperature of water in the sea, the investigation of the presence or concentration of oil and specific components, the investigation of other physical and chemical properties, and the evaluation using the results. Camera or CCD as sensor
May be used.

[0038]

In the measurement according to the present invention, high-precision measurement can be stably performed in the depth direction underground or underwater without disturbing the measurement environment for a long time at a plurality of points in the measurement target area. Speaking of groundwater measurement, natural groundwater changes (rainwater infiltration into groundwater, etc.) can be measured with high accuracy over a wide range. In addition, since it is possible to measure a wide range of electrical conductivity fluctuations that can respond to injection of a high electrical conductivity medium, groundwater fluctuations can be measured in a time series by measuring the flow form and diffusion of the high electrical conductivity medium. Its practical value is extremely high because it can measure spatial variations due to horizontal deployment.

According to the present invention, the measurement can be performed without stopping the characteristic detecting sensor in the boring hole near the predetermined depth in the boring hole, and the measurement can be performed for a long time. become. Therefore, it is very effective for monitoring a temporal change or a spatial change of the characteristic. Examples of suitable embodiments of the present invention include monitoring of the inflow of surface water, such as rainfall, into groundwater, monitoring of the inflow of saltwater into the underground at the shore, and the formation of saltwater or hot water from other boring holes. Estimation of the state of diffusion of the fluid in the inside is mentioned.

In the present invention, measurement can be performed by suspending 20 or more sensors from the ground with one signal cable. In addition, in order to ensure the simultaneousness of measurement, it is possible to electrically give a measurement instruction from a control unit on the ground, and to perform all measurements with 120 or more sensors within a few seconds. In addition, the measurement interval and the measurement start time can be arbitrarily set, so that the measurement can be performed for a short period to a long period. In the present invention, since the automatic measurement is performed by the computer, the labor involved in the measurement and the number of personnel involved in the measurement can be significantly reduced as compared with the related art.

[Brief description of the drawings]

FIG. 1 shows a conceptual diagram of a measurement system according to the present invention.

FIG. 2 shows a connection state between an electric conductivity sensor and a cable.

FIG. 3 is a perspective view of the electric conductivity sensor used in the present embodiment.

FIG. 4 shows a block diagram of the electrical circuit of the electrical conductivity sensor.

FIG. 5 is a block diagram of an electric circuit of the entire measurement system according to the present invention shown in FIG. 1;

FIG. 6 shows the types of measurement signals and their timing charts.

FIG. 7 is a real-time chart showing measurement results obtained in the present embodiment.

FIG. 8 shows a graph of electrical conductivity as a measurement result obtained in the present embodiment.

[Explanation of symbols]

11, 12, 13, 14, 15 Cable 21-26 Data transmitter 30 Signal control unit 31 Data input board 32 Data recording unit 33 Data display unit 34 Power supply unit 50 (1), 50 (2), 50 (20) shift Register 51 (1), 51 (2) Sensor amplifier 52 (1), 52 (2), 52 (20) Switch 53, 53 (1), 53 (2), ... 53 (20) Electrode 60 Hanging cable 61 Suspension plate 62 Cable 63 Connector 70 Cylindrical sleeve 71 Centralizer 100 Measurement center

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01D 21/00 G08C 19/00 (72) Inventor Toshio Furuta 2-11-15 Mita, Minato-ku, Tokyo Kawasaki Geological Co., Ltd. (72) Inventor Hiroaki Tsubaba 7-2-3, Ibukidai, Nishi-ku, Kobe-shi, Hyogo Alec Electronics Co., Ltd. F-term (reference) 2F073 AA01 AB01 BB04 BB11 BB12 BC01 CC02 CC03 CC07 CC10 CD01 CD11 CD17 DD04 DE02 DE03 FF12 FF14 FG02 GG01 GG04 GG07 GG09 2F076 BB12 BD02 BD07 BE09 BE17

Claims (7)

[Claims] At each of a plurality of points in a measurement target area, a plurality of characteristic detection sensors are connected to a single signal cable at a predetermined interval and hung. A measurement command is sequentially given to the sensors via the signal cable in synchronization with each other, and measurement data sequentially output by each sensor is collected via the signal cable.Underground or undersea physical or chemical A method of measuring characteristics. 2. A plurality of boring holes drilled in a measurement target area, a plurality of characteristic detection sensors spaced apart from each other by a predetermined distance, connected to one signal cable and suspended, and each boring hole is disposed. Control means for sequentially giving a measurement command to the group of sensors arranged in the hole via the signal cable in a synchronized manner, and data collecting means for collecting measurement data sequentially output by each sensor via the signal cable. A system for measuring physical or chemical properties underground or in the sea, characterized by: 3. The measuring method according to claim 1, wherein said characteristic detecting sensor is an electric conductivity sensor. 4. The measurement system according to claim 2, wherein said characteristic detection sensor is an electric conductivity sensor. 5. The measuring method according to claim 1, wherein said characteristic detecting sensor further includes a temperature sensor. 6. The measurement system according to claim 2, wherein the number of characteristic detection sensors connected to one signal cable is 20 or more. 7. The measurement system according to claim 2, wherein a boring hole used for artificially changing a characteristic to be measured is formed in addition to the plurality of boring holes.