JP2002357666A - Method for predicting collapse and breakage of ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the prediction of breakage and collapse of ground and enhance the reliability of the prediction. SOLUTION: Two or more profile lines differed in length are set in a prediction subject area GA where the ground is predicted to be unstable, electrodes 1 are set on both sides thereof, and the ground potential difference is measured between the electrodes 1 and 1, respectively. The measured ground potential difference data are recorded every fixed time by a data logger 2, and transmitted to a personal computer 7 set in an observation station or the like through a data transmitting means 3, where necessary processing such as noise removal or the like is performed to evaluate a collapse or breakage precursory phenomenon of the ground of the area GA.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a soil which is expected to become unstable due to slope works such as embankment or cut and various civil works such as tunnel excavation, or a case where stratification becomes unstable due to weathering or the like. The present invention relates to a technology for predicting the occurrence of a ground collapse or a destructive phenomenon such as a landslide, a landslide, or a tunnel face destruction in an expected ground.

[0002]

2. Description of the Related Art In Japan, landslides, landslides, rock landslides, debris flows, etc., not only on slopes of artificially modified lands where the earth and rocks have been shaved or embanked and civil engineering has been performed, but also on natural slopes with a stable ground structure. Many slope disasters have occurred, especially during the rainy season and heavy rains due to typhoons, which has become a major social problem. In particular, the collapse of the slope on the Echizen coast in Fukui Prefecture (1989) and the collapse of the rock at the entrance of the Toyohama Tunnel in Hokkaido (1996), which were accompanied by human damage, are new to memory.

[0003] General roads such as national roads and prefectural roads, highways,
Infrastructure such as railways and Shinkansen is particularly public.
With the construction, safety monitoring of the back slope formed by embankment and cutting has become an issue. In addition, around 64,000 places with dangerous danger of steep slope collapse, about 62,000 places of dangerous mountain stream with debris flow, and about 6,000 places of landslide danger are designated in various parts of the country, and various landslides are taken as countermeasures. Countermeasures and construction of sabo dams, etc. are being promoted.

[0004] In order to avoid such a danger on an unstable slope, it is effective to predict the occurrence of a ground disaster. Conventionally, the following method has been adopted as such prediction means. . a. Ground displacement measurement by landslide extensometer (between immovable pile and movable pile), inclinometer in boring hole, light wave survey, etc. b. Measurement of ground strain (stress) using a rebar strain gauge, anchor axial force gauge, pipe strain gauge in a borehole, etc. c. When the ground breaks, A is a minute sound generated as a result of releasing the strain energy that the ground has stored up to that time.
E (acoustic emission) is measured by an AE sensor installed on an anchor bolt or the like. D. Meteorological observation of short-time rainfall, accumulated rainfall, temperature, humidity, etc. e. Judgment of cracks in the ground and the sound of lining concrete and visual observation of crack propagation, etc.

[0005] Of the above-mentioned conventional methods, a and b are considered to have a high possibility of collapse or have already fluctuated (there is evidence of fluctuations now or in the past). It is a method to measure by installing an instrument, and it is an effective method when the sliding and activity history of the collapse area etc. are clarified to some extent. The reinforcing bar strain gauge and the anchor axial force meter can be measured only when a reinforcing bar is inserted into the ground or a ground anchor is constructed as a countermeasure.

In the conventional method c, the AE generated when the ground is deformed or destroyed is a very small sound, so that the energy is greatly attenuated at the time of propagation and is not very close to the point where the failure occurs. Is difficult.

Among the above-mentioned conventional methods, d is not a method for directly measuring the ground deformation, but is based on weather conditions which are thought to induce the ground collapse, especially rainfall, and the groundwater fluctuation resulting therefrom. It is to judge sex.

[0008] Of the above-mentioned conventional methods, e is a visual inspection by a human, and in reality, this method is mainly used for monitoring a back slope such as an expressway or a railway. Judgment criteria are not quantitative, tend to be influenced by experience and intuition, and require large labor and cost, but are relatively reliable.

[0009]

However, in the above-described conventional method, the location, scale,
It is very difficult to predict when it will occur. In addition, the installation and maintenance costs of various measuring instruments are high, it takes a long time to install, and in many cases, it is difficult to install the measuring instruments because of the inaccessibility of people and instruments. There is also the possibility of an electrical malfunction.

In addition, the above-mentioned conventional method has universality in an evaluation method for predicting the occurrence of ground collapse from various physical values such as measured or observed ground displacement, strain, AE sound, and rainfall. Therefore, it is difficult to set a threshold value for determining that the ground collapses when the measured value exceeds a certain value, or to find a physical basis thereof.

[0011] Further, it is rare that an area or a slip surface predicted to possibly cause ground destruction or collapse is clarified in advance. For this reason, in the conventional method described above, In most cases, it is difficult to select the installation position of the measuring device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its technical subject the ability to easily predict the destruction and collapse of the ground and to improve the reliability of the prediction. To increase.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a rock or a mineral is subjected to a strain such as a compressive force, a tensile force or a shearing force, so that a dielectric polarization or an electric field is generated in the mineral and a large electric power is generated immediately before the mineral is destroyed. A method that predicts the occurrence of ground collapse or destruction by using changes in the earth potential due to the piezo effect, such as the release of energy, and applies a method that is said to be an effective means for earthquake prediction It was done. That is, in the method for predicting the collapse and destruction of the ground according to the invention of claim 1, a plurality of survey lines having different lengths are set in the prediction target area where the ground is expected to be unstable, and electrodes are installed at both ends thereof. Then, from the ground potential difference change data measured between the electrodes, the collapse or precursory phenomenon of the ground in the prediction target area is evaluated.

[0014] The term "ground" as used in the present invention is a generic term that includes not only ground consisting of soil layers and gravel layers, but also rock mainly composed of rocks. The “ground potential difference” is, as is well known, a potential difference in the ground, and “ground current”
It can also be rephrased.

According to a second aspect of the present invention, there is provided a method for predicting collapse and destruction of a ground, wherein each of the survey lines having different lengths is set in a horizontal plane direction or a vertical direction at a plurality of locations on the ground. From the ground potential difference data measured on each survey line,
The purpose of the present invention is to evaluate the landslide or precursory phenomenon of the ground in the prediction target area.

According to a third aspect of the present invention, there is provided a method for predicting collapse / destruction of a ground according to the second aspect of the present invention, wherein a ground sample collected from the ground in a prediction target area is loaded by a laboratory test device made of an insulating material; The potential difference between the plurality of electrodes attached to the sample is measured, and from this data, the pattern of the absolute ground potential difference data measured on each measurement line in the prediction target area is evaluated.

According to a fourth aspect of the present invention, there is provided a method for predicting collapse / destruction of ground, according to any one of the first to third aspects, wherein the ground potential difference data V measured at each measurement line is measured by a measurement line length L.
Using the V / L divided by the above or the reciprocal L / V, the collapse or the precursor phenomenon of the ground in the prediction target area is evaluated.

According to a fifth aspect of the present invention, there is provided a method for predicting collapse or destruction of a ground according to any one of the first to fourth aspects, wherein one or more survey lines are set in a ground stable region remote from the prediction target region. Electrodes are installed at both ends, and the ground potential difference data measured on the survey line is compared to filter the ground potential difference data measured on the survey line in the prediction target area.

According to a sixth aspect of the present invention, in the method for predicting collapse / destruction of ground, in the fifth aspect of the invention, the measurement timings of the respective survey lines are synchronized with each other.

According to a seventh aspect of the present invention, there is provided a method for predicting ground collapse / destruction according to any one of the first to sixth aspects, wherein a ground potential difference between each electrode is recorded by a data logger, and the recorded ground potential difference data is recorded. Is transmitted from the data transmitting means to the data processing means provided at a predetermined location remote from the prediction target area, and the data logger and the data transmitting means are driven by a solar power supply.

According to a eighth aspect of the present invention, there is provided a method for predicting collapse / destruction of a ground according to the seventh aspect, wherein, among a plurality of electrodes installed on the ground, an electrode connected to an anode-side input terminal of a data logger and a cathode. A method of measuring the absolute potential difference between each pair of electrodes by arbitrarily selecting the electrodes connected to the side input terminal, and measuring the relative potential difference between a single common electrode and multiple other electrodes Choose a way to do it.

According to a ninth aspect of the present invention, in the method for predicting the collapse or destruction of the ground, in the invention of the seventh or eighth aspect, other ground displacement data or ground strain data is input to the data logger together with the ground potential difference data. You.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for predicting ground collapse / destruction according to the present invention, as described above, predicts the occurrence of ground collapse or destruction by evaluating changes in ground potential due to ground distortion. Is what you do. In order to verify the basis of the evaluation, FIG. 1 is an explanatory diagram showing a point load test for measuring a change in an absolute potential difference in a rock in the process of applying a strain to a rock in a room and breaking the rock.

That is, in the point load test shown in FIG. 1, a pair of pressing elements 101, 1 opposed to each other are used.
01, a rock sample 100 is placed,
Are attached to both ends of the data logger 103 and connected to the input terminals of the data logger 103, respectively. Presser 101,
101 is made of an insulating material such as bakelite, and is insulated from the pedestals 104 on both sides by insulating paper 105, respectively. Presser 101, 1
Numeral 01 is formed in a pointed shape so as to make point contact with the rock sample 100, and one of the pressing elements 101, 101 can advance and retreat in the opposite direction by the propulsive force of the spiral shaft 106. I have.

FIG. 2 is a diagram showing a measurement result by the point load test shown in FIG. That is, in the unloaded state before the loading on the rock sample 100, the electrode 10
The potential difference measured between the electrodes 102 and 102 shows a change with a small amplitude of about 0.5 mV. When the loading of the rock sample 100 between the pressers 101 and 101 is started, the electrodes 102 and The measured value as a whole shows an upward trend, while the potential difference between 102 changes with a relatively long period and an amplitude of several mV. When the applied load is further increased, micro-destruction of the internal structure of the rock sample 100 starts, and the period of the change in the potential difference is sharply shortened, and eventually the rock sample 100 is broken. The potential drops rapidly due to the release of electrical energy. Even during the actual ground destruction process, it is considered that the change of the ground potential difference shows an approximate pattern.

Therefore, for example, a columnar core-shaped ground sample is previously taken by boring from a ground region where there is a possibility that the ground will be collapsed or destroyed, and this ground sample is obtained by the point load test as described above. If the distortion is given under various conditions such as changing the water content, and the correlation between the distortion amount and the ground distortion signal is grasped,
It is useful for estimating the scale and timing of ground collapse and destruction.

Next, FIG. 3 is an explanatory view showing a method for performing a collapse test of a simple embankment slope indoors. In this test,
A simulated embankment 110 was formed of sand so that the height h = 150 mm, the lower surface length a = 350 mm, and the slope gradient θ = 45 °, and both side surfaces in the width direction were supported by a pair of parallel support plates 112. . In the surface layer portion (upper layer portion), middle layer portion, and lower layer portion (lower layer portion) of the simulated embankment 110, in the process of forming the simulated embankment 110, each is located near the slope 110a and near the end opposite to the slope 110a. Embedded a pair of electrodes 111,
A voltmeter (data logger), not shown, was connected between the electrodes 111 of each layer. In addition, a position near the slope 110a on the upper surface 110b of the simulated embankment 110 is pressed by the loading device 113 in the vertical direction.

FIG. 4 is a diagram showing the measurement results of the simple embankment slope shown in FIG. 3 by a collapse test. That is, as the loading by the loading device 113 is increased, cracks are periodically generated inside the simulated embankment 110. Each time, the absolute potential difference is gradually increased due to the increased loading, and the occurrence of cracks or It can be seen that changes similar to those in FIG. 2 are repeated, such as a sharp decrease in the absolute potential difference due to discharge during the progress. Further, in the lower layer portion of the simulated embankment 110, almost no potential change is observed because no destruction occurs, while the upper layer has a larger potential change.

Next, FIG. 5 is an explanatory view showing a collapse test of the embankment slope larger than that of FIG. In this test, a simulated embankment 120 was formed with sand material so that the height h = 500 mm, the lower surface length a = 1000 mm, and the slope gradient θ = 45 °, and both sides in the width direction of the simulated embankment 120 were supported by a pair of parallel supports. It was supported by a plate (not shown). A plurality of electrodes 121a to 121c, 121d to 12c connected to the anode of a data logger (not shown) are provided on the surface layer, middle layer, and lower layer of the simulated embankment 120.
1g, 121h to 121j are respectively buried at appropriate intervals in the horizontal direction, and a common electrode 1 connected to the cathode of the data logger is provided at an end of the lower layer opposite to the slope 120a.
22 was embedded. Also, the upper surface 120 of the simulated embankment 120
The position near the slope 120a in FIG.
To press in the vertical direction.

The load applied by the loading device 123 can be measured by the load cell 124.
Further, a water supply means (not shown) using a shower is arranged above the simulated embankment 120 so that simulated rainfall can be given. Furthermore, the upper surface 120b of the simulated embankment 120
A vertical displacement meter 125 is disposed on the slope 120a of the simulated embankment 120, and a displacement measurement target T is disposed at a height corresponding to the surface portion, the middle layer portion, and the lower layer portion. By measuring with the total 126, the displacement of the simulated embankment 120 due to the load from the loading device 123 can be measured.

In the test shown in FIG. 3, the change in the absolute potential difference between each pair of electrodes embedded in the surface layer, the middle layer, and the lower layer was measured, whereas the test shown in FIG. Then, each electrode 121a to 121a-
The relative potential difference between the two electrodes was measured and evaluated in mV / mm (mV: potential difference between both electrodes, mm: distance between both electrodes). FIG. 6 is an explanatory diagram in which the relative potential difference distribution in the cross section of the simulated embankment 120 is expressed by density of points from the value of mV / mm measured by this test.
The value of V / mm is-, and the area represented by a dense point is mV
The value of / mm is +. The black rectangle indicates the position of the electrode. That is, when the loading by the loading device 123 is increased, polarization occurs in the simulated embankment 120, and the boundary between the positive side and the negative side of the relative potential difference clearly appears in a curved shape,
Along this curve, the slip surface LS as shown in FIG.
Is formed.

FIG. 7 is an explanatory view schematically showing a case in which a collapse prediction of a cut slope is performed according to the present invention. This FIG.
In the figure, reference numeral A is a cut slope constructed by cutting a ground G having a natural slope indicated by a chain line in the figure. Near ground of Cut slope A that are expected is likely to collapse as the prediction target ground area G _A, embedded a plurality of electrodes 1,1, ... and in this ground area G _A and the vicinity thereof, the electrodes 1, Are connected to the anode-side input terminal and the cathode-side input terminal of the high-precision data logger 2 via the conductor 2 and an amplifier (not shown), and a ground potential difference (ground current) is measured.

Depending on which of the electrodes 1, 1,... Is connected to the anode-side input terminal of the data logger 2 and which electrode is connected to the cathode-side input terminal, FIG. As described, the case of measuring the absolute potential difference between each pair of electrodes and the case of measuring the relative potential difference between a plurality of anodes and one common cathode can be selected according to the situation at the site and the like. it can.

For example, when the electrode 1 is installed on the surface layer of the ground, a wire connected to a rebar or a rock bolt is preferably used. When the electrode 1 is installed underground, a boring hole is formed by drilling a hole. And a zinc or lead electrode embedded therein. The method of installing the electrodes in the borehole is the same as the installation of the inclinometer in the borehole in the prior art described above, or the strain gauge or the like in the borehole. Absent.

The data logger 2 measures the ground potential difference between the electrodes 1 and 1 at regular time intervals (1 to 10 seconds) and records the measured data as time histories. Is transmitted to the receiver 5 of the site office at intervals of a fixed time (for example, 10 minutes to 1 hour) longer than the measurement interval by the data logger 2, and further transmitted to the observation base via a communication network 6 such as a telephone line. Is transmitted to the personal computer 7 installed in the PC. The data logger 2 and the wireless modem 3 are driven by a solar power supply 4 which does not cause artificial noise as described later. The solar power supply 4 includes a solar cell (solar panel) 41 and a battery 42 for storing the electromotive force generated here.

Since the data logger 2 has a plurality of input channels, measurement data other than the ground potential difference between the electrodes 1 and 1 can be simultaneously obtained. For example, the topographical conditions of the prediction target ground area G _A, and the anchor axial force meter, installed and landslide meter, the measurement by them, carried out in synchronization with the earth potential measurement between the electrodes 1, 1, the data Can be captured.

The personal computer 7 at the observation base is
The data sent from the data logger 2 at each observation site is processed, and necessary processing such as noise removal and relative potential difference calculation described above is performed, the results are evaluated in real time, and the evaluation data is displayed. 71 or a printer 72 or the like.

The data logger 2 performs the measurement operation of the data logger 2 via the wireless modem 3 because it is important to compare and examine the observation data at several different points in predicting the collapse and destruction of the ground. Remote control can be performed. Also, different points (observation sites)
Since the plurality of data loggers 2 need to compensate for the synchronization of the measured data, the measurement timings are synchronized with each other by a GPS built-in clock (not shown).

The ground potential data actually measured between the electrodes 1 and 1 contains various noises. The noise includes global-scale noise (global noise) such as fluctuations in earth potential due to changes in geomagnetism due to sunspot activity of the sun, and changes in ground potential due to low tide and high tide on the sea surface, and human activities. Originated, for example, artificial noise in which the ground potential fluctuates due to leakage current or electromagnetic waves from factory or home electrical equipment or trains, or regional noise such as changes in groundwater due to rainfall or changes in ground potential due to lightning strikes (Local noise). Unless such noise is almost completely removed, it is difficult to accurately determine a change in a ground potential difference (hereinafter referred to as a ground distortion signal) corresponding to only the strain stress in the ground region to be predicted.

Most of the noise is global noise. To remove the global noise measures noise in noise survey line set at a point sufficiently distant from the prediction target ground area G _A (not shown). That is, global noise appear simultaneously in all of the measurement signal between the electrodes of the measuring line, since the change of the ground distortion signal by the distortion stress of the prediction target ground area G _A is local, the prediction target ground area G _A the ground potential data measured by the electrodes 1,1, which ground distortion signal and noise corresponding to the strain stress of the prediction target ground area G _a are mixed, while the ground potential was measured in the noise measuring line data Since almost no ground distortion signal is included, all of the signals can be regarded as noise. Thus by this noise, if filtering ground potential data in the prediction target ground area G _A, it is possible to remove the global noise.

On the other hand, the local noise can be removed by evaluating the surrounding electromagnetic wave environment based on measurement results such as a waveform of a ground potential difference when a train is passing through a nearby railway. Also, as described above, the data logger 2
Since the wireless modem 3 is driven by the solar power supply 4, the wireless modem 3 itself does not cause artificial noise as compared with the case where a commercial power supply (AC 100 V) containing noise is used. Moreover, by using the solar power supply 4,
There are various advantages such as being less susceptible to external noise due to lightning strikes in the vicinity and being easily installed in mountainous areas where commercial power cannot be secured, or in dangerous places where it is difficult for people to enter.

[0042] As described above, the signal obtained by removing the global noise and local noise can be regarded as ground distortion signal corresponding to the distortion stress of the prediction target ground area G _A. Therefore, from the change data of the ground distortion signal, it is possible by the evaluation method described above, to predict and ground collapse timing and scale of the prediction target ground area G _A.

FIG. 8 is an explanatory view showing an example of the arrangement of the electrodes 1 when the present invention is implemented in a wide landslide risk area on a natural slope, and the broken lines in the figure are contour lines. The ground in the area shown in FIG. 8 is one in which volcanic ash is deposited, and a cliff B due to a collapse is formed in a steep part.
The valley C extends from there. In the vicinity of the cliff B, a short measurement line S1 extending in the direction of ground collapse and a plurality of short measurement lines S2 extending in a direction substantially perpendicular thereto are set by a pair of electrodes 1 and 1, respectively. A pair of electrodes 1 and 1 respectively define a long measurement line L1 and a long measurement line L2 extending in a direction substantially orthogonal to the valley C along the overall direction over the entire length of the valley C. .

The short measurement lines S1 and S2 are for monitoring a landslide on a steep slope, and have a length of about 50 to 100 m. The long measurement lines L1 and L2 monitor debris flow at the valley V and have a length of one to several kilometers.

By setting a plurality of measurement lines having different electrode-to-electrode distances, an area having a large difference is determined from the distance between the electrodes (the length of the measurement line) and the amount of change in the ground potential difference between the electrodes. It is possible to identify that the ground is unstable.

[0046]

According to the method for predicting the collapse and destruction of the ground according to the first aspect of the present invention, a plurality of measurement lines having different lengths are set, electrodes are installed at both ends, and the ground measured between the electrodes is measured. From the data on the change in the potential difference, the phenomenon of precursory collapse or destruction of the ground in the prediction target area is evaluated, and highly reliable prediction can be performed.

According to the method for predicting the collapse or destruction of the ground according to the second aspect of the present invention, the absolute ground potential difference is measured on each measurement line and the fluctuation is evaluated to determine the scale and timing of the destruction and destruction of the ground. A highly reliable prediction can be made.

According to a third aspect of the present invention, there is provided a method for predicting collapse / destruction of a ground according to the second aspect of the present invention, wherein a change pattern of an absolute potential difference when a strain is applied to a ground sample taken from the ground in a prediction target area. Is obtained in advance, a highly reliable prediction can be performed from the pattern of the absolute ground potential difference data measured on each measurement line in the prediction target area.

According to the method for predicting the collapse or destruction of the ground according to the fourth aspect of the present invention, V / L obtained by dividing the ground potential difference data V measured on each survey line by the survey line length L or its reciprocal L
From the difference of / V, highly reliable prediction can be made for a region where collapse or destruction of the ground is predicted to occur.

According to the ground collapse / destruction prediction method according to the fifth aspect of the present invention, one or more noise survey lines are set in a ground stable region distant from the prediction target region, so that the measured data in the prediction target region can be obtained. Since noise can be removed and only a ground distortion signal corresponding to the distortion stress of the ground can be extracted, highly reliable prediction based on highly accurate data can be performed.

According to the method for predicting collapse / destruction of the ground according to the sixth aspect of the present invention, since the measurement timings of the respective survey lines are synchronized with each other, it is possible to accurately perform matching of the respective data for noise removal. it can.

According to the method for predicting ground collapse / destruction according to the seventh aspect of the present invention, since the data logger and the data transmitting means are driven by a solar power supply, noise is not generated by itself, and noise due to lightning strike or the like is not generated. Since it is hardly affected by the measurement, highly accurate measurement can be performed. Further, automatic measurement can be easily performed in a mountainous area where a commercial power supply cannot be secured or in a dangerous place where it is difficult for humans to enter.

According to the method for predicting the collapse or destruction of the ground according to the invention of claim 8, the plurality of electrodes installed on the ground include:
By arbitrarily selecting the electrode connected to the anode input terminal and the electrode connected to the cathode input terminal of the data logger,
A method of measuring the absolute potential difference between each pair of electrodes and a method of measuring the relative potential difference between one common electrode and a plurality of other electrodes can be selected. Thus, by adopting an appropriate measurement method, highly reliable prediction can be performed.

According to the method for predicting the collapse / destruction of the ground according to the ninth aspect of the present invention, the data logger receives the data measured by other means together with the ground potential difference data between the electrodes. The reliability of prediction can be further improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a point load test for measuring a change in an absolute potential difference in a rock in a process of applying a strain to a rock by compressive force in a room and breaking the rock.

FIG. 2 is a diagram showing a measurement result by a point load test shown in FIG. 1;

FIG. 3 is an explanatory view showing a method of performing a collapse test of a simple embankment slope indoors.

FIG. 4 is a diagram showing measurement results of a collapse test of the simple embankment slope shown in FIG. 3;

FIG. 5 is an explanatory diagram showing a collapse test of an embankment slope larger than that of the simple embankment slope shown in FIG. 3;

FIG. 6 shows the values measured by the test shown in FIG.
It is explanatory drawing which represented the relative electric potential difference distribution in the cross section of a simulation embankment by shading.

FIG. 7 is an explanatory diagram schematically showing a case in which a cut slope failure prediction is performed according to the present invention.

FIG. 8 is an explanatory diagram showing an example of the arrangement of the electrodes 1 when the present invention is implemented in a wide landslide risk area on a natural slope.

[Explanation of symbols]

Reference Signs List A Cut slope G Ground G _A prediction target area 1,102,121a-121j, 122 Electrode 2,103 Data logger 3 Wireless modem (data transmission means) 4 Solar power supply 6 Communication network 7 Personal computer 100 Rock sample (ground sample) 101 Presser

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideyuki Murayama 4-16-15 Sendagaya, Shibuya-ku, Tokyo Inside Fujita Co., Ltd. (72) Inventor Takuo Kato 4-6-115 Sendagaya, Shibuya-ku, Tokyo Stock F-term in Fujita (reference)

Claims (9)

[Claims] 1. A plurality of survey lines having different lengths are set in a prediction target region where the ground is expected to be unstable, electrodes are installed at both ends thereof, and a change in a ground potential difference measured between the electrodes is set. From the data, evaluation of the ground collapse or precursory phenomenon of the ground of the prediction target area is characterized by
Failure prediction method. 2. Each survey line having a different length is set at a plurality of locations on the ground in a horizontal plane direction or a vertical direction, and based on geoelectric potential difference data measured at each survey line, a sign of collapse or destruction of the ground in the prediction target area. The method according to claim 1, wherein the phenomenon is evaluated. 3. A ground sample collected from the ground in the region to be predicted is loaded by a laboratory test device made of an insulating material, and a potential difference between a plurality of electrodes attached to the sample is measured. 3. The method according to claim 2, wherein a pattern of absolute ground potential difference data measured by each measurement line of the area is evaluated. 4. V / L obtained by dividing the ground potential difference data V measured on each measurement line by the measurement line length L or its reciprocal L /
The ground collapse / destruction prediction method according to any one of claims 1 to 3, wherein V is used to evaluate a ground collapse or a precursory phenomenon of the ground in the prediction target area. 5. At least one survey line is set in a ground stabilization region apart from a prediction target region, and electrodes are installed at both ends thereof.
The ground potential difference data according to any one of claims 1 to 4, wherein the ground potential difference data measured in the survey line is compared, and the ground potential difference data measured in the survey target region is filtered. Failure prediction method. 6. The method according to claim 5, wherein the measurement timings of the respective measurement lines are synchronized with each other. 7. A ground potential difference between the electrodes is recorded by a data logger, and the recorded ground potential difference data is transmitted by a data transmission unit to a data processing unit installed at a predetermined location remote from the prediction target area, 7. The method according to claim 1, wherein the logger and the data transmission unit are driven by a solar power supply. 8. An electrode connected to an anode-side input terminal and an electrode connected to a cathode-side input terminal of a data logger are arbitrarily selected from among a plurality of electrodes installed on the ground, so that each pair of electrodes can be connected. The method according to claim 7, wherein a method of measuring an absolute potential difference and a method of measuring a relative potential difference between a single common electrode and a plurality of other electrodes are selected. Forecasting method. 9. The data logger according to claim 7 or 8, wherein other ground displacement data or ground strain data is input together with the ground potential difference data.
Failure prediction method.