JP2000098051A - Optical ground surveyor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical ground surveyor which performs ground survey swiftly and simply. SOLUTION: A light transmitting part 4 is provided on the external wall to be in touch with the ground 1 of a ground penetration substance 3, and one end of a projecting optical fiber 6 and one end of a receiving optical fiber 9 are fitted to the inside of the penetration substance 3, linking them to the light transmitting part 4 optically. The other end of the projecting optical fiber 6 is optically linked to a light source 12, and the other end of the receiving optical fiber 9 is optically linked to a detector 13. A reflected light data 16 from an already-known geology of the light of the light source 12 is stored in a reflected-light storing means 15. A ground geology 25 is identified, by comparing a data 26 of a reflected light from an underground geology 25 to be applied to the detector 13 via the receiving optical fiber 9, when the light of the light source 12 is emitted to the underground geology 25 via the projecting optical fiber 6, with the reflected light data 16 of the storing means 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical ground surveying apparatus, and more particularly to a method for measuring ground light based on a comparison between reflected light data obtained when light is projected onto the underground geology of the ground via an optical fiber and reflected light data of a known geology. The present invention relates to a ground survey device for identifying underground geology.

[0002]

2. Description of the Related Art In recent years, the number of cases where the contamination of the ground by oil or the like has become a problem has been increasing, and the development of purification technology for contaminated soil has been promoted. When treating contaminated soil, a ground survey to determine the approximate area of the contaminated ground (hereinafter sometimes referred to as a rough survey), the types of contaminants in the ground where the contamination was found in the rough survey, A two-stage ground survey is required, which includes a detailed survey of the total amount and concentration distribution, etc. (hereinafter sometimes referred to as a detailed survey). Conventional main ground survey methods are a core sampling analysis for analyzing columnar soil or rock called a core collected by a boring device, or a cone penetration test device.

[0003]

However, the ground survey method based on core sampling analysis has a problem that it takes a very long time because a cycle of ground drilling, core sampling, and core analysis is repeated. In addition, when a ground survey is performed at many points as in a rough survey, if all the ground surveys are performed by core sampling analysis, there is a problem that the cost increases. In particular, in the case of contaminated soil purification, the ratio of the ground survey cost to the total cost tends to be large because the overall cost is smaller than that of construction work, etc. Has become. There is a demand for the development of a technology that can quickly and easily investigate the ground.

On the other hand, a pore water pressure gauge is provided in a cone penetration test device,
The development of a technology for attaching various sensors such as an electric resistance sensor and a three-component cone to continuously inspect the ground in the depth direction has been advanced. According to this method, the ground can be surveyed in real time. However, this ground survey method
Since a relatively expensive sensor that can withstand the penetration is required to penetrate the sensor into the ground, it is difficult to perform a ground survey using a plurality of sensors simultaneously.
Some sensors are suitable for ordinary soil surveys but not for polluted ground surveys.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical ground inspection apparatus which can perform a ground inspection quickly and easily.

[0006]

SUMMARY OF THE INVENTION The present inventor has proposed a method of projecting light from a light source to a target via a light emitting optical fiber and inputting reflected light from the target to a detector via a light receiving optical fiber. Attention was paid to a sensor using an optical fiber for detecting an attribute of an object (hereinafter, referred to as an optical fiber sensor). An optical fiber sensor can be manufactured in principle from a light emitting diode, a photodiode and a plastic fiber, and the manufacturing cost is very low.

[0007] The following experiment was conducted to confirm whether it is possible to identify geology composed of soil and rock, particularly contaminated geology, using an optical fiber sensor. In this experiment, as a geological sample, a sandy soil (hereinafter, referred to as white sand) having a maximum particle size Dmax = 2 mm and a uniformity coefficient Uc = 3.27 and having a substantially uniform particle size, and a sandy soil obtained by coloring it with black ink using black ink ( Hereinafter, it is referred to as black sand). As a contaminated geological sample, 0.5, for each of white sand and black sand,
Four types were used in which 1.0, 3.0 and 10.0% by weight of fuel oil C were well mixed. 100 g of each of the two types of C-heavy oil-free samples and the eight types of C-heavy oil-mixed samples were packed in beakers to obtain geological samples.

As shown in FIG. 1, a test penetrator 3 made of a transparent acrylic resin and having a diameter Φ = 150 mm, a length L = 170 mm, and a conical end is manufactured as shown in FIG. The light emitting end of the optical fiber 6 and the light receiving end of the light receiving fiber 9 were arranged. The other end of each of the light projecting fiber 6 and the light receiving fiber 9 was taken out from the rear end of the test penetrator 3 in the penetrating direction, and connected to the light source 12 and the detector 13, respectively.

[0009] One end of the conical shape of the test penetrator 3 penetrates the geological sample in the beaker, a red light is applied from the light source 12 to the light projecting end, and the light intensity of the reflected light from the geological sample is measured by the detector 13. did. This experiment was performed in a dark room to remove the influence of light from the outside. FIG. 3 shows a graph of the experimental results.
In the graph of FIG. 3, white circles indicate measured values of white sand, and black circles indicate measured values of black sand. The horizontal axis in FIG. 3 represents the concentration of heavy fuel oil C (% by weight), and the vertical axis represents the relative intensity of the light reflected from each sample when the light intensity of the light reflected from white sand without the addition of heavy fuel oil was 1.0. Light intensity (hereinafter, referred to as relative light reception amount).

As can be seen from the graph of FIG. 3, when the oil contamination concentration of both white sand and black sand is 3% by weight or less, the oil contamination concentration and the relative amount of received light are substantially proportional. Therefore, if the prerequisites are held down in the preliminary examination or the like as a condition, or according to the flowchart described later, it is possible to quantitatively grasp the oil contamination concentration by measuring the relative received light amount. When the oil contamination concentration is 3% by weight or more, the relative received light amount becomes almost constant,
Although it indicates heavy contamination, it is difficult to quantitatively grasp the contamination concentration based on the relative received light amount. However, considering actual oil-contaminated soil surveys, it is considered sufficient if quantitative identification of a certain level of contamination concentration is possible within the range of oil contamination concentration of about 3% or less.

From this experiment, it was confirmed that the degree of oil contamination of both white sand and black sand can be determined by the optical fiber sensor. That is, regardless of the color of the sandy soil itself, the contaminated sandy soil can be identified by the optical fiber sensor. A graph similar to that in Fig. 3 can be created for geology other than sandy soil. Based on the detection of reflected light from geology by an optical fiber sensor, detection of the presence or absence of oil and other contaminants, and quantification of the concentration of contaminants It is possible to grasp the target. Regarding the identification other than the contaminated geology, if the reflected light data of various known geology is detected and recorded, the geology to be investigated can be identified based on the record. The present invention has been completed based on these findings.

Referring to the embodiment shown in FIG. 1, an optical ground survey apparatus according to the present invention includes a light transmitting portion 4 on an outer wall to be in contact with the ground 1.
A ground light penetrating body 3 having one end optically coupled to the light transmitting portion 4 at one end inside the penetrating body 3 and optically coupled to the light source 12 at the other end; A light receiving optical fiber 9 which is optically coupled to the light transmitting portion 4 and is optically coupled to the detector 13 at the other end, and stores reflected light data 16 from a known geology with respect to light from the light source 12. The reflected light data from the underground geological material 25 which is applied to the detector 13 via the light receiving optical fiber 9 when the light from the light source 12 is projected on the underground geological material 25 via the reflected light storing means 15 and the light projecting optical fiber 6 26 (see FIG. 5) and the reflected light data of the storage means 15
It is provided with an identification means 19 for identifying the underground geology 25 by comparing it with the underground geology 25.

Preferably, one end of the light projecting optical fiber 6 is attached to the penetrating body 3 so as to project the light in the same direction as or perpendicular to the direction of penetration. More preferably, as shown in FIG.
A cleaning device 20 for the outer surface of the light transmitting unit 4 is attached to the outside of the penetrator 3.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A penetrating body 3 can be penetrated into a ground 1 by a penetrating device 30 (see FIG. 8) or the like.
The light transmitting portion 4 is provided on at least a part of the outer wall in contact with the light transmitting portion. The light transmitting section 4 is optically coupled to one end of the light emitting optical fiber 4 (hereinafter, referred to as a light emitting end) and one end of the light receiving optical fiber 9 (hereinafter, referred to as a light receiving end). It serves as a medium for light between the light receiving end and the underground geology 25, and may be made of, for example, glass or acrylic resin.

Although the embodiment shown in FIG. 1 shows a long penetrating body 3 extending from the ground surface to the underground geology 25, the penetrating body 3 only needs to be able to guide the light emitting end and the light receiving end to the underground geology 25, and its size is sufficient. Is not limited to the illustrated example. For example, the penetrator 3 of the present invention can be provided by providing a light transmitting portion 4 on the outer wall of a cone used in a conventional cone penetration test device.

For example, the light transmitting portion 4 can be provided at the front end of the penetrating body 3 in the penetrating direction, and the light projecting end can be projected in the same direction as the penetrating direction. However, in this case, the translucent portion 4 needs to have a strength that can withstand the pressure applied during penetration from the ground 1. This is to prevent the measurement accuracy from deteriorating due to damage to the light transmitting portion 4 due to collision with hard geological features such as rocks. More preferably, as shown in FIG. 1, the light transmitting portion 4 is provided on the side wall of the penetrating body 3, and the light is projected from the light transmitting end in a direction perpendicular to the penetrating direction.

The coupling of the light projecting end and the light receiving end to the light transmitting section 4 is as follows.
For example, passages of the optical fibers 6 and 9 are formed in the penetrating body 3 from the rear end in the penetrating direction to the light transmitting part 4, and the light transmitting end and the light receiving end are inserted into the passage from the rear end of the penetrating body 3 to transmit the light transmitting part 4. Can be combined with The other end of the light projecting optical fiber 4 (hereinafter referred to as a light source coupling end) and the other end of the light receiving optical fiber 9 (hereinafter referred to as a detection end) are coupled to a light source 12 and a detector 13 provided on the ground surface, for example. As a result, the penetrator 3 can be guided to the ground from the rear end. However, the method of coupling the light transmitting part 4 to the light emitting end and the light receiving end, and the installation positions of the light source 12 and the detector 13 are not limited to this example.

The light source 12 may be, for example, a light source for red light, green light, or other monochromatic light, and the detector 13 may be, for example, a detector for detecting the light intensity of light reflected from the known geology 25. In this case, the light intensity of the reflected light from the known geology is stored in the reflected light storage unit 15 as the reflected light data 16 of the known geology.

When a red light source is used as the light source 12 and the known geology is the above-described non-contaminated and white sand / black sand of a predetermined contaminated concentration, the curves 16W and 16B of the relative received light amount shown in FIG. Optical data 16 can be used. The following experiment 1 was performed to confirm that the underground geology in the ground can be identified based on the curves 16W and 16B of the relative received light amount shown in FIG.
And 2 were performed.

[Experiment 1] In order to simulate the underground geology of oil pollution, as shown in FIG.
A test ground was prepared by filling 4 cm in height of white sand mixed with 0% by weight of heavy fuel oil C and filling the upper layer with 4 cm in height of sand containing no oil. After that, a test penetrator 3 made of acrylic resin similar to that shown in FIG. 1 was penetrated into the test ground from the ground surface, and the depth distribution of the relative received light amount was measured. FIG. 4B shows the measurement results.
Is indicated by a white circle. As can be seen from the white circle graph in FIG. 4B, the relative light receiving amount was 1.0 when the depth from the ground surface was 1 cm, 2 cm, and 3 cm, and the relative light receiving amount was about 0.6 when the depth was 5 cm and 6 cm. By comparing the graph of the white circle in FIG. 4 (B) with the curve 16W of the relative received light amount indicated by the white circle in FIG. 3 by the identification means 19, non-contaminated soil is found at a depth of about 4 cm from the ground surface of the test ground. Underground geology deeper than about 4 cm is about 1.
The oil-contaminated soil was identified as 0% by weight.

[Experiment 2] A test ground was prepared in which the lower layer of the beaker was filled with 4 cm high white sand mixed with 3.0% heavy fuel oil in place of the oil-contaminated white sand of Experiment 1 in place of the 1.0 wt% oil-contaminated white sand. Was measured for depth distribution. The measurement results are indicated by crosses in FIG. By comparing the graph of the crosses in FIG. 4B with the curve 16W of the relative received light amount indicated by the white circle in FIG. 3, in this experiment, the identification means 19 also revealed that the underground geology deeper than about 4 cm was about 3.0% by weight. Oil-contaminated soil.

That is, from the experimental results of FIG. 4B, the reflected light data 16 of the known geology is stored and compared with the reflected light data 26 from the underground geology 25 when the light is projected on the underground geology 25 (see FIG. 5). By doing so, it was confirmed that underground geology 25 was identifiable. It can also be confirmed from the figure that the reflected light data 26 from the same underground geology is almost constant irrespective of the change in depth from the ground surface.

Therefore, for example, as shown in FIG.
When 25 reflected light data 26 are added to the detector 13, the identification unit 19 outputs the reflected light data 26 and the reflected light data 16 of the known geology.
By comparing with, the underground geology between the depths D ₁ and D ₂ can be identified.

In FIG. 1, the reflected light storage means 15 is a memory on the computer 14 and the identification means 19 is a program built in the computer. If necessary, reflected light data can be input from the input means 17 and input to the storage means 15 for storage, and the identification result and the like can be displayed on the display means 18 such as a display. However, the storage unit 15 and the identification unit 19 are not limited to the illustrated example.

Although the embodiment in which the monochromatic light source 12 is used and the reflected light data 16 is used as the relative amount of reflected light has been described, the light source 12 and the reflected light data 16 of the present invention are not limited to this example. For example, the light source 12 is a visible light source, the detector 13 is provided with a spectrocolorimeter for reflected light from the underground geology 25, and the color of the reflected light from the known geology 25 is stored in the storage means 15 as reflected light data 16. The identification means 19 can identify the contaminated geology and other underground geology 25 based on the comparison between the color of the light reflected from the underground geology 25 by the spectrophotometer and the color of the light reflected by the storage means 15. Further, the underground geology 25 can be identified using the light source 12 of ultraviolet light or laser light.

The optical ground survey device of the present invention can be manufactured at low cost by using an optical fiber, and the survey cost can be kept low even when the ground survey is performed by using a plurality of devices. If the reflected light data of the known geology is stored, the underground geology can be easily identified by the intrusion of the intruded body into the ground, so that the time required for the ground survey can be reduced as compared with the conventional core sampling analysis. By applying the present invention, the number of points for core sampling analysis can be minimized, especially when ground surveys are required at many points, thereby reducing the cost of ground surveys and shortening the construction period. Can be achieved.

In this way, the object of the present invention, that is, the provision of the "optical ground inspection apparatus capable of performing the ground inspection quickly and easily" can be achieved.

When the ground survey device of the present invention continuously conducts a survey up to a depth of about 10 m, it may be considered that soil or the like adheres to the translucent portion 4 of the penetrator 3 and it becomes difficult to accurately identify the underground geology. Can be For example, it is desirable to clean the outer surface of the light transmitting section 4 about once every 2 m in depth. In this case, a method in which a cleaning liquid or the like is caused to flow on the outer surface of the translucent section 4 to wash off the attached matter is conceivable. However, the cleaning liquid affects the light from the light source 12 and / or the reflected light from the underground geology 25, and causes a measurement error. There is a possibility that. In the embodiment of FIG. 2, a cylindrical or conical penetrator 3 is shown.
The outer surface cleaning device 20 fitted to the outer wall including the light transmitting portion 4 is provided.

The outer surface cleaning device 20 shown in FIG. 1 has a partially notched sheath 21 which is slidably tightly fitted to the outer wall of the penetrator 3 including the light transmitting portion 4. At the time of acquiring the reflected light data from the underground geology 25, the notch of the sheath 21 and the light transmitting portion 4 are aligned.
The size of the notch is equal to or larger than the size of the light transmitting portion 4. At the time of cleaning, the sheath 21 is slid on the outer wall of the penetrating body 3 to release the alignment between the notch of the sheath 21 and the light transmitting portion 4. When the alignment is released, the seal on the outer periphery of the light transmitting portion 4 slides on the outer surface of the light transmitting portion 4 so that the deposits on the outer surface of the light transmitting portion 4 can be removed.

[0030]

FIG. 6 shows an example of a flow chart of a process for investigating contamination of the ground 1 composed of a plurality of strata by the ground inspection apparatus of the present invention. First, in step 501, the stratum configuration of the surveyed ground is grasped, and in step 502, a curve of the reflected light data 16 as shown in FIG. For example, underground geology 25a, 25a shown in FIG.
In the case of three-layered ground consisting of b and 25c,
FIG. 7 (B) is obtained by preparing samples of a, 25b, and 25c in a state where there is no oil contamination and in a state of a predetermined contamination concentration, and acquires the reflected light data 16 by penetrating the test penetrator 3 for each sample. Reflected light data 16a, 16 as shown in)
Create b and 16c curves. Created reflected light data 16a, 1
The curves 6b and 16c are stored in the reflected light storage means 15.

Next, at step 503, the ground penetrating body 3 is penetrated into the ground 1, and at step 504, the reflected light data 26 from the underground geology 25a, 25b, 25c is acquired. In step 505, it is determined which of the underground geology 25a, 25b, 25c the reflected light data 26 is reflected from based on the penetration position of the intruding body 3, and the underground geology 25a, 25b acquired in step 504 is determined. , 25c
The reflected light data 26 from any of the reflected light data 16a, 1
Compare with curves 6b and 16c. In step 506, the presence or absence of oil contamination of the underground geology 25a, 25b, and 25c and / or the measurement of the oil contamination concentration, that is, the identification of the underground geology 25, are performed based on the result of the comparison. In step 507, determine the end of the ground survey,
If the investigation is to be continued, return to step 503, and further penetrate 3
And continue the geological survey.

The reflected light data is considered to be determined not only by the color of the underground geology 25 but also by the geological composition such as the gap of the underground geology 25 and the water content. According to the flow chart of No. 6, it was confirmed that the underground geology 25 can be identified.

Further, by adding a pore water pressure gauge, an electric resistance sensor, a three-component cone, and / or a thermometer to the intruder 3, it is possible to more accurately identify the underground geology 25.

FIG. 8 shows an example of a ground penetrating device 30 for penetrating the ground penetrating body 3 of the present invention into the ground. The general range of oil contamination is about 10 m deep, and it is necessary to penetrate the ground penetrating body 3 to a depth of about 10 m in order to investigate the underground geology 25 of oil pollution. The ground penetrating device 30 in the figure is
A cylinder 32 perpendicular to the ground surface, a hammer 31 driven vertically to the ground surface supported by the cylinder 32, and a hammer
And an extendable rod 33 which is driven into the ground by 31. First, the penetrating body 3 is attached to the lower end of the short rod 33, and the rod 33 and the penetrating body 3 are penetrated into the ground by a hammer 31 from the upper end of the rod 33.
By continuing to hit the hammer 31 while adding the pressure, the penetrating body 3 can be penetrated to a desired depth. In this case, the lengths of the optical cables 6 and 9 for light emission and light reception are also 10 m or more.

Further, instead of the hammer 31 shown in FIG. 8, a method of penetrating the penetrating body 3 using a rotary drill is also possible. However, the method of penetrating the penetrating body 3 in the present invention is not limited to a method using a driving hammer or a rotary drill. For example, the penetrating body 3 is attached to a lower end of a support rod of about 2 to 3 m, and an operator pushes the support rod into the ground 1. It is also possible to make it penetrate.

[0036]

As described above, the optical geological survey apparatus of the present invention projects the reflected light data from the known geology with respect to the light of the light source and the light of the light source to the underground geology via the light emitting optical fiber. Since the underground geology is identified by comparison with the reflected light data from the underground geology detected via the light receiving optical fiber when the light is emitted, the following remarkable effects are obtained.

(A) Since the manufacturing cost of the ground survey device is low, the survey cost can be reduced even when the ground survey is performed using a plurality of devices. (B) The depth of underground geology in the depth direction can be identified in real time by the intrusion of the intruded body into the ground, so that the time required for the ground survey can be significantly reduced compared to the conventional core sampling analysis. (C) By applying the present invention when it is necessary to conduct surveys at many points, it is possible to minimize the number of points for core sampling analysis, thereby reducing the cost of ground surveys and shortening the construction period. Shortening can be achieved. (D) Accurate identification of underground geology of underground geology having different geological compositions such as gaps and water content is also possible by comparing the data with reflected light from an appropriate known geology.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of the device of the present invention.

FIG. 2 is an explanatory diagram of a cleaning device for an outer surface of a light transmitting unit.

FIG. 3 is a graph showing a correlation between an oil contamination concentration and a relative light reception amount.

FIG. 4 is an explanatory diagram of identification of underground geology by comparing relative light reception amounts.

FIG. 5 is an explanatory diagram of an example of reflected light data from underground geology;

FIG. 6 is an explanatory diagram of identification of underground geology based on a relative amount of received light.

FIG. 7 is an explanatory diagram of a method for investigating contamination of the ground composed of a plurality of strata.

FIG. 8 is an explanatory diagram of a ground penetration device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Soil 2 ... Soil survey device 3 ... Soil penetrating body 4 ... Transmissive part 6 ... Light emitting optical fiber 7 ... Light emitting end 8 ... Light source coupling end 9 ... Light receiving optical fiber 10 ... Light receiving end 11 ... Detection end 12 ... Light source 13 ... Detector 14 ... Computer 15 ... Reflection light storage means 16 ... Reflection light data of known geology 17 ... Input means 18 ... Display means 19 ... Identification means 20 ... Outer surface cleaning device 21 ... Partially notched sheath body 22 ... Notch peripheral seal 25 25 Underground geology 26 ... Underground geology reflected light data 30 ... Ground penetration device 31 ... Hammer 32 ... Cylinder 33 ... Rod

Claims (8)

[Claims] 1. A ground penetrator having a light-transmitting portion on an outer wall to be in contact with the ground, one end of which is optically coupled to the light-transmitting portion inside the penetrator and mounted on the other end, and the other end of which is optically connected to a light source. A light-receiving optical fiber, one end of which is optically coupled to the light-transmitting portion and which is attached to the inside of the penetrator, and the other end of which is optically coupled to the detector; Reflected light storage means for storing reflected light data from a known geology with respect to the light source, and is applied to the detector via the light receiving optical fiber when the light from the light source is projected onto the underground geology via the light emitting optical fiber. An optical ground survey device comprising identification means for identifying the underground geology by comparing reflected light data from the underground geology with reflected light data from the storage means. 2. An optical ground survey device according to claim 1, wherein one end of said light projecting optical fiber is attached to said penetrator so as to project light in the same direction as or perpendicular to the direction of penetration. 3. The ground survey device according to claim 1 or 2,
An optical ground survey device comprising a cleaning device for cleaning the outer surface of the light-transmitting portion outside the penetrator. 4. An optical ground surveying device according to claim 1, further comprising a penetrating means for penetrating the penetrating body into the ground. 5. The ground surveying device according to claim 1, wherein the light of the light source is visible light, the reflected light data of the storage means is the color of the reflected light from the known geology, A spectrocolorimeter for the reflected light from the underground geology, and the identifying means for identifying the underground geology based on a comparison between the color of the light reflected by the spectrocolorimeter and the color of the reflected light from the storage means. Optical ground survey equipment. 6. The ground survey device according to claim 1, wherein the light of the light source is monochromatic light, and the reflected light data of the storage means is the light intensity of the reflected light from the known geology.
An optical ground surveying apparatus, wherein the identification means is an identification means for the underground geology based on a comparison between a light intensity of reflected light applied to the detector and a light intensity of reflected light from the storage means. 7. The ground survey device according to claim 5, wherein
An optical geological survey apparatus wherein the known geology is a geology with a known oil pollution concentration and a non-polluting geology, and the identification means measures the presence or absence of oil contamination and / or the oil contamination concentration of the underground geology. 8. The ground survey device according to claim 1, wherein said penetrator has a pore water pressure gauge, an electric resistance sensor,
An optical ground survey device to which a component cone and / or a thermometer are added.