JP5718186B2 - Method and apparatus for predicting ground displacement - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a technical field of a ground displacement prediction method and a prediction device for predicting ground displacement that may cause landslides such as landslides, surface layer collapse, and landslides that may occur on unstable slope ground. is there.

In general, there is a landslide disaster as one of natural disasters. Examples of such a landslide disaster include disasters caused by landslides, surface collapses, landslides, debris flows, and the like that occur on slopes.
Such a landslide disaster on a sloping ground is caused by ground collapse, that is, ground displacement, in which the slope ground is deformed or moved. Therefore, it is important to predict the occurrence of ground displacement in order to prevent landslide disasters.
Conventionally, with respect to a technique for measuring ground displacement, for example, as disclosed in Patent Document 1, a measurement hole is dug in an arbitrary place where ground displacement is generated, a strain cable is inserted therein, and ground displacement is detected. There is one that measures the displacement of the ground by measuring the amount of distortion caused by.
However, this requires expensive measuring equipment, and measures the ground displacement during or after the slope failure actually occurs, and predicts the occurrence of the ground displacement. is not.
On the other hand, as shown in Patent Document 2, ion concentrations of specific ions such as sodium ions and sulfate ions contained in groundwater in areas where there is a risk of ground displacement due to slope failures such as landslides and surface failure. When the measured value rises rapidly, there is one that predicts that this is a precursor to the occurrence of ground displacement due to slope failure such as landslide and surface layer failure.
In this case, when the soil particles become finer due to the progress of weathering etc., the stress in the ground changes and a slip surface is generated, and the growth of this slip surface further refines the soil particles near the slip surface. The groundwater that has passed through the surface of the finely divided soil particles has a higher ion concentration than the groundwater that has passed through the surface of relatively large soil particles that are not subjected to sliding force. Then, the ion concentration of groundwater flowing through the area subject to ground displacement measurement is continuously measured, and when the ion concentration increases, it is observed that a slip surface has occurred somewhere in the ground through which the groundwater has passed. It is predicted that there is a high possibility of ground displacement due to the occurrence of a slip surface.

Japanese Patent No. 2847180 Japanese Patent No. 4219100

  The thing of patent document 2 is estimating the ground displacement as a slip surface having occurred when the ion concentration of groundwater which flows through the observation object area of ground displacement is continuously measured, and the ion concentration changes rapidly. In this way, there was no previous attempt to observe the occurrence of slip surfaces that could cause ground displacement before the disaster occurred, and to predict future ground displacement. It is groundbreaking in that it can detect the occurrence of a slip surface with a certain degree of reliability and predict the ground displacement based on the detection of the occurrence of the slip surface. It was.

However, when observation was continued thereafter, a sudden rise in ion concentration was observed in this prediction method, and even if a slip surface was observed, ground displacement such as landslide or surface collapse did not occur after that. There was a case. In other words, it was found that the occurrence of a slip surface is one of the factors that cause ground displacement, but is not the only cause of ground displacement.
Assuming that a slip surface has occurred, what other factors exist in the process from the occurrence of the slip surface to the occurrence of ground displacement, from the occurrence of the slip surface to the actual occurrence of ground displacement? The solution of the present invention is to find out a method capable of predicting the occurrence of more accurate ground displacement by identifying such factors and elucidating the relationship between the factors and the occurrence of ground displacement. There are issues to be addressed.

The present invention was created to solve these problems in view of the above circumstances, and the invention of claim 1 is considered to generate ground displacement due to slope failure such as landslide and surface failure. If the ion concentration of specific ions present in the groundwater of a certain area is continuously measured, and there is a change in which the ion concentration of the specific ions increases rapidly, ground displacement will occur due to slope failure such as landslide and surface layer collapse. In the prediction method for predicting that there is a possibility of occurrence, when the ion concentration suddenly increases, the increase rate with respect to the average ion concentration observed before the rapid increase is calculated, and the increase rate is preset. If it is higher than the set magnification, it is predicted that there is a high possibility of ground displacement regardless of precipitation after the rapid increase in the ion concentration. Predicted that there is a high possibility that ground displacement will occur when the continuous precipitation reaches the preset continuous precipitation during the period from the day when the rapid increase in the ion concentration is observed until the predetermined period In order to do so, the set magnification is set as a first set magnification, a magnification lower than the first set magnification is set as a second set magnification, and the ion concentration increase magnification is set between the first set magnification and the second set magnification. In the case of a short period, ground displacement may occur if the continuous precipitation reaches the preset continuous precipitation during the period from the day when the rapid increase of the ion concentration is observed until the predetermined period. If it is not reached, it is predicted that the possibility of ground displacement is low, and if it is lower than the second set magnification, the ground displacement is not affected by the precipitation after the rapid increase in ion concentration. Is less likely to occur It has to be expected that the prediction method of the ground displacement, characterized in.
The invention of claim 2 continuously measures the ion concentration of specific ions existing in the groundwater in the area where the ground displacement due to slope failure such as landslide and surface layer collapse occurs, and the ion concentration of the specific ions rapidly increases. In the prediction device that predicts that there is a possibility that ground displacement due to slope failure such as landslide and surface layer failure will occur when there is a sudden rise in the ion concentration, before the sudden rise An ascending rate calculating means for calculating an ascending rate with respect to the observed average ion concentration, and when the increasing rate is higher than a preset set rate, the ground regardless of the precipitation after the rapid increase in the ion concentration; While it is predicted that the possibility of displacement is high, if the rate of increase is lower than the set rate, continuous from the day when the sudden increase is observed until a predetermined period Upon water is constituted by a prediction means for predicting the likely to occur in the ground displacement when it reaches the set continuous precipitation set in advance, the predicting means, the first set magnification the set magnification And a lower magnification than the first set magnification is registered as the second set magnification, and the predicting means, when the increase rate of the ion concentration is between the first set magnification and the second set magnification, It is predicted that the possibility of ground displacement is high if the continuous precipitation reaches the preset continuous precipitation during the period from the day when the rapid rise of the water is observed to the predetermined period. If it is not, it is predicted that the possibility of ground displacement is low, and if it is lower than the second set magnification, the possibility of ground displacement is low regardless of the precipitation after the rapid increase in ion concentration. It is set to predict DOO is a predictor of ground displacement, characterized in.

With the invention of claim 1 or 2, it can be more certainty may predict the occurrence of ground displacement causing such landslides and slope failure.

It is a schematic explanatory drawing which shows the mode of the soil particle inside a ground. It is a schematic explanatory drawing which shows the mode of the growth of a slip surface, and the ground displacement. It is a schematic explanatory drawing of the area where ion concentration shows background concentration, baseline concentration, and peak concentration. It is a graph which shows the relationship between ion concentration and the amount of ground displacement. It is the schematic of the microcomputer used for the ground displacement prediction apparatus. It is a flowchart figure of the control part for estimating a ground displacement.

  In general, slope failures such as landslides and surface layer failures are thought to occur due to instability of the ground due to weathering or the like. That is, the soil particles in the stable ground are relatively large soil particles (soil particles 1) as shown in FIG. 1, but the microscopic displacement of the soil particles or Breaking occurs and the soil particles are in a state of being finer than the soil particles 1 (soil particles 2). In such a place where the ground is destabilized, the soil mass moves due to the change of the stress in the ground, and the slip surface 3 may be generated in the ground due to the movement of the soil mass (FIG. State). And when this sliding surface 3 grows and becomes large, displacement of the ground 4 may occur (state of FIG. 2 (B)), and finally this grown sliding surface becomes a sliding surface. The entire ground may move and cause landslide disasters such as landslide collapse (state shown in FIG. 2C).

  On the other hand, as shown in FIG. 3, the rainwater (surface water) that falls in the area subject to the observation of ground displacement contains sea salt-derived particles or smoke-derived particles floating in the air when it reaches the surface of the ground. For example, low concentrations of sodium ions, calcium ions, chlorine ions, sulfate ions, etc. are observed. The ion concentration of rainwater on the surface of the ground is set as the background concentration.

The rainwater that falls in the observation target area infiltrates from the surface of the earth into the ground, and is collected as groundwater while passing between the soil particles on the ground.
Rainwater is composed of water, but water molecules generally have a strong polarity, and therefore, between ion-exchange groups on the surface of soil particles (for example, silanol groups and hydroxyl groups bonded to silicon atoms). It is known to actively exchange ions. For this reason, the rainwater that has permeated the ground has an ion concentration higher than the background concentration by ion exchange. The ion concentration of groundwater after passing through the ground is taken as the baseline concentration.

  By the way, when the sliding surface 3 is generated, a large force acts near the sliding surface, so that the soil particles near the sliding surface are destroyed and refined, and this increases the effective surface area of the entire soil particles near the sliding surface. In addition, the number of ion exchange groups on the surface of the soil particles also increases. For this reason, the amount of ions (ion concentration) in the groundwater that has passed near the slip surface after the occurrence of the slip surface temporarily rises compared to the groundwater that has passed before the occurrence of the slip surface. In this way, the ion concentration that is higher than the baseline concentration due to the occurrence of the slip surface is taken as the peak concentration.

  In this way, the rainwater that falls in the observation target area penetrates into the ground from the ground surface and exchanges ions with the soil particles in the process of becoming groundwater, so the groundwater that has passed through the ground in the observation target area. The ion concentration of the soil reflects the geomechanical or chemical state of the ground, and as described above, if the ion concentration of groundwater rises from the baseline concentration to the peak concentration, It can be estimated that a slip surface has occurred in any of the above. It can be estimated that the larger the rate of increase when the ion concentration increases from the baseline concentration to the peak concentration, the larger the scale of the generated slip surface.

Figure 4 shows the specific ions (sodium ion, calcium ion) obtained by continuously measuring the groundwater passing through the area for about 4 years from the observation start date of the area where the landslide was actually observed. It is a graph which showed ion concentration value (mg / L) and the displacement amount (mm) of the ground in the specific observation point of this area.
The ground of the observation target area is mudstone whose surface layer is strongly weathered, and landslides have repeatedly occurred in the past.
The displacement of the ground is measured by inclinometers a and b installed at the innermost part of the inclinometer hole by excavating inclinometer holes at two locations close to the landslide occurrence site in the area. is there. The inclinometer a is installed at a position with a depth of 7 m, and the inclinometer b is installed at a position with a depth of 3 m.
Moreover, the measurement of the concentration of sodium ions (Na ⁺ ) and calcium ions (Ca ²⁺ ) in groundwater is performed using groundwater stored in the dipmeter hole on the foot side of the two dipmeter holes as an analysis sample. We are doing what we have collected. The amount collected was 100 mL (milliliter) of groundwater, collected every 6 days, and put into a polyethylene bottle for analysis. The analysis quantifies sodium ions (Na ⁺ ) and calcium ions (Ca ²⁺ ) in the collected ground water using ion chromatography / electric conductivity detection method.

  In FIG. 4, when the concentration of ions such as sodium ions and calcium ions rapidly changes, it can be estimated that a slip surface has occurred somewhere in the ground of the observation target area as described above. However, looking at the amount of ground displacement during a few months after such a rapid increase in ion concentration is observed, the ground is not necessarily greatly displaced. There is not always a clear relationship between the two. In other words, the occurrence of a slip surface estimated from a sudden rise in ion concentration is a factor of ground displacement, but when the ground displacement is actually caused, there is a factor different from the occurrence of a slip surface. It is reasonable to think that ground displacement is induced when this factor satisfies some condition.

  By the way, if ground displacement has occurred despite the fact that the ion concentration has not risen sharply due to such measurements, it can be considered that the groundwater being measured has not passed through the slip surface that caused the ground displacement. I can do it. If ground displacement occurs in a certain area, the groundwater in the area does not necessarily pass through the slip surface that would have caused the ground displacement. Therefore, in order to predict the ground displacement more accurately, it is necessary to grasp the route of groundwater that passes through the ground in the observation target area.

Then, what is the factor that causes the ground displacement after the slip surface is generated using the slip surface as a sliding surface? The first major factor that causes ground displacement is the earthquake, and the second is the precipitation. And in Japan, which has a rainy climate, precipitation is a natural phenomenon that occurs more frequently than earthquakes, and each time it rains, water permeates from the surface to the ground and continues to affect the ground. Especially when it rains without interruption due to stagnation of the rainy season front or typhoon, the rainwater that penetrates into the ground as well as the rainwater flowing on the surface will increase over time, and it will be easy to cause landslides etc. Is well known. Therefore, the inventor of the present invention observes the continuous precipitation after the ion concentration suddenly increases in the ground of the observation target area, and the causal relationship between the observed continuous precipitation and the occurrence of ground displacement after the rapid increase of the ion concentration. investigated.
The continuous precipitation observed here is the total precipitation from the beginning to the end of precipitation when there is continuous precipitation such as rain or snow, and the beginning of precipitation is 0.5 mm per hour. When the above precipitation is observed, the end of falling is exemplified by the case where precipitation of less than 0.5 mm per hour continues for 6 hours or more. In other words, even if precipitation of less than 0.5 mm per hour is observed, if the observed time does not continue for 6 hours or more, it is determined that it has not ended. However, the amount of precipitation and the continuous time, which are the criteria for determining the beginning and end of rain, can be set arbitrarily according to the observed ground and local conditions. Of course, it is not limited to the numerical value setting.

The inventors of the present invention observed the relationship between the continuous precipitation after the rapid increase in ion concentration in the observation target area and the subsequent occurrence of ground displacement over a long period of time, and the following characteristic phenomenon occurred. The present invention has been completed.
(1) When the rate of increase in ion concentration is very high In this case, the rate of increase in ion concentration is high, so it is assumed that the scale of the slip surface generated on the ground is quite large, and the ion concentration has increased rapidly. Later, it was confirmed that there was a high possibility that ground displacement would occur regardless of precipitation up to several months. In such a case, it is assumed that the scale of the slip surface was large enough to cause ground displacement independently of the factors related to precipitation.
(2) The increase rate of the ion concentration is not as high as in the case of (1), but the ion concentration is increasing at a higher increase rate compared to the ion concentration before the increase. 1) Although it is not as high as that, it is presumed that a moderate-scale slip surface has occurred. In this case, after this ion concentration rises, some continuous precipitation will occur for several months. It was confirmed that there is a high possibility that ground displacement will occur after that. In such a case, it is assumed that the occurrence of the slip surface and the precipitation amount cause direct ground displacement.
(3) When the rate of increase in ion concentration is lower than (2) In this case, the rate of increase in ion concentration is low, so it is assumed that the occurrence of a slip surface is small. It was confirmed that the possibility of ground displacement is low regardless of the precipitation during the period. In such a case, it is assumed that the possibility of ground displacement is low regardless of the factors related to precipitation.

  In this way, the occurrence of ground displacement can be predicted with high accuracy by measuring continuous precipitation along with the measurement of ion concentration. However, when such occurrence of ground displacement is predicted, the increase in ion concentration The rate and continuous precipitation vary depending on the measurement location and are not constant. For this reason, it is needless to say that the classifications (1) to (3) are determined by data observed in advance at the measurement location.

In the following, the relationship between the rapid increase in ion concentration in the ground shown in FIG. 4 and the subsequent continuous precipitation and ground displacement will be analyzed for each case.
(A) to (G) in FIG. 4 are points where the ion concentrations of sodium ions and calcium ions rapidly increased and peak concentrations exceeding 100 mg / L were observed. In these (A) to (G), When the continuous precipitation (mm) was examined for 3 months from the day when the maximum peak concentration was obtained, the following facts were confirmed.

(A) The ion concentration increased rapidly from March to April in the first year of observation, and a peak concentration exceeding 100 mg / L was observed. On April 10, the highest peak concentration was observed. When continuous precipitation of the ground was measured for three months from the day when the maximum peak concentration was observed, continuous precipitation exceeding 60 mm was not observed. No large ground displacement was observed from the day when the ion concentration rapidly increased until the next day when the ion concentration rapidly increased.
(B) The ion concentration rapidly increased from October to November in the first year of observation, and a peak concentration exceeding 100 mg / L was observed. On October 1, the maximum peak concentration was observed. When the continuous precipitation of the ground was measured for three months from the day when the highest peak concentration was observed, continuous precipitation exceeding 60 mm was observed on November 10. On November 15th, a ground displacement of about 2 mm was observed.
(C) The ion concentration rapidly increased in July one year after the start of observation, and a peak concentration exceeding 300 mg / L was observed. On July 20, the maximum peak concentration was observed. When continuous precipitation of the ground was measured for three months from the day when the maximum peak concentration was observed, continuous precipitation exceeding 60 mm was observed on September 20, but the previous 8 A ground displacement of about 7 mm on September 13 and about 2 mm on September 15 was observed.
(D) One year after the start of observation, the ion concentration increased rapidly from October to November, and a peak concentration exceeding 100 mg / L was observed. On October 3, the maximum peak concentration was observed. When continuous precipitation of the ground was measured for three months from the day when the highest peak concentration was observed, continuous precipitation exceeding 60 mm was not observed. No large ground displacement was observed from the day when the ion concentration suddenly increased until the next day when the ion concentration rapidly increased.
(E) The ion concentration increased rapidly from March to July two years after the start of observation, and a peak concentration exceeding 100 mg / L was observed. On April 3, the maximum peak concentration was observed. When the continuous precipitation of the ground was measured for three months from the day when the highest peak concentration was observed, continuous precipitation exceeding 60 mm was observed on June 5. On June 13, a ground displacement of about 4 mm was observed.
(F) The ion concentration rapidly increased from December two years after the start of observation to January three years after the start of observation, and a peak concentration exceeding 100 mg / L was observed. Observed. When continuous precipitation of the ground was measured for three months from the day when the highest peak concentration was observed, continuous precipitation exceeding 60 mm was not observed. No large ground displacement was observed from the day when the ion concentration suddenly increased until the next day when the ion concentration rapidly increased.
(G) The ion concentration rose rapidly from August to October three years after the start of observation, and a peak concentration exceeding 100 mg / L was observed. On August 20, the peak concentration showed the maximum value. When continuous precipitation of the ground was measured for three months from the day when this peak concentration showed the highest value, continuous precipitation exceeding 60 mm was not observed. A large ground displacement was not observed until the end of December, 3 years after the start of observation, which was the observation end date.

The phenomena confirmed in (A) to (G) can be analyzed as follows.
(I) In the phenomenon of (C), the value of the rapidly increasing ion concentration increases to about 5 times the average value of the ion concentration during the two months before the ion concentration rapidly increases. In this case, there was a large ground displacement of 7 mm on August 13 before September 20, which is the day when the continuous precipitation exceeded 60 mm in the three months from the day when the peak value of the ion concentration was observed. Then, a ground displacement of about 2 mm was observed on September 15th. From this, when the ion concentration increased greatly as shown in (C), the ground displacement occurred regardless of the subsequent precipitation. It can be said that there is a high possibility of doing.
(Ii) In the phenomena of (B) and (E), the value of the rapidly increasing ion concentration is between about twice and four times the average value of the ion concentration observed during the two months before the ion concentration rapidly increased. It has become. Then, continuous precipitation exceeding 60 mm was observed for 3 months from the day when the maximum peak concentration was observed, and ground displacement occurred several days after the continuous precipitation was observed. Therefore, when the concentration value of the ion concentration at which the rapid increase was observed was about 2 to 4 times the average value of the ion concentration during the two months before the rapid increase in the ion concentration was observed, the highest ion concentration was obtained. If the continuous precipitation exceeds 60 mm during the three months from the day when the value was observed, it can be said that there is a high possibility of ground displacement.
(Iii) In the phenomena of (D) and (F), the value of the rapidly increasing ion concentration is between about twice and four times the average value of the ion concentration observed during the two months before the ion concentration rapidly increases. It has become. However, no continuous precipitation exceeding 60 mm was observed for 3 months from the day when the highest peak concentration was observed. No significant ground displacement was observed from the day when the rapid increase in ion concentration was observed until the next day when the rapid increase in ion concentration was observed. Therefore, when the concentration value of the ion concentration at which the rapid increase was observed was about 2 to 4 times the average value of the ion concentration during the two months before the rapid increase in the ion concentration was observed, the highest ion concentration was obtained. If the continuous precipitation does not exceed 60 mm during the three months from the day when the value was observed, it is unlikely that ground displacement will occur.
(Iv) In the phenomena of (A) and (G), the value of the rapidly increasing ion concentration is not more than twice the average value of the ion concentration observed during the previous two months. And in the case of (A), the next day from the day when the rapid rise in ion concentration was observed despite continuous precipitation exceeding 60 mm was observed for 3 months from the day when the highest peak concentration was observed. No significant ground displacement was observed until the day when a rapid increase in ion concentration was observed. On the other hand, in the case of (G), continuous precipitation exceeding 60 mm is not observed for 3 months from the day when the highest peak concentration is observed, and then 12 years after the start of observation, which is the observation end date of ground displacement. No significant ground displacement was observed until the end of the month. Therefore, if the concentration value of the ion concentration at which the rapid increase was observed was less than twice the average value of the ion concentration during the two months before the rapid increase in the ion concentration was observed, regardless of the subsequent precipitation It can be said that the possibility of ground displacement is low.

From such an analysis, the relationship between continuous precipitation and ground displacement when the ion concentration changes rapidly can be estimated as follows.
In the case of (i), the increase rate of the rapid increase of the ion concentration is higher than the first set magnification of 4 times, which indicates that a large slip surface has occurred, It is highly probable that ground displacement will occur regardless of the subsequent precipitation.
In the case of (ii) and (iii), the increase rate of the rapid increase of the ion concentration is lower than 4 times that is the first setting magnification and higher than 2 times that is the second setting magnification. It is estimated that the possibility of ground displacement depends on the amount of continuous precipitation.
In the case of (iv), the increase rate of the rapid increase of the ion concentration is lower than the second setting magnification of 2 times, and when the ion concentration increases to such a level, there is a slip surface that causes displacement of the ground. It is presumed that it has not occurred, and it is estimated that the possibility of ground displacement is low regardless of the precipitation after the rapid increase in ion concentration.

Based on such estimation, when the ion concentration changes rapidly, the increase rate of the rapidly increasing ion concentration with respect to the ion concentration before the rapid increase and the continuous precipitation in the predetermined period after the ion concentration sudden increase A method for predicting the occurrence was found.
(I) When a rapid increase in the ion concentration is observed, the increase rate with respect to the average value of the ion concentration observed during the two months before the sudden increase in the rapidly increased ion concentration is calculated, and when the increase rate is 4 times or more, Regardless of precipitation, there is a high possibility of subsequent ground displacement. Here, although the ascending magnification of 4 is set as the reference magnification, this is set as the first setting magnification.
(Ii) When a rapid increase in the ion concentration is observed, a rate of increase with respect to the average value of the ion concentration observed during the two months before the rapidly increasing ion concentration is calculated, and the rate of increase is 2 to 4 times. If it is less than 60 mm, if the continuous precipitation observed over 3 months from the day when the maximum value of the ion concentration is observed exceeds 60 mm, ground displacement will occur after the continuous precipitation is observed. Probability is high.
(Iii) When a rapid increase in the ion concentration is observed, a rate of increase with respect to the average value of the ion concentration observed during the two months before the sudden increase in the rapidly increased ion concentration is calculated, and the rate of increase is 2 to 4 times. If it is less than 60 mm, if the continuous precipitation observed for 3 months from the day when the maximum value of ion concentration is observed does not exceed 60 mm, the ground displacement will be measured before the next rapid increase in ion concentration is observed. Is unlikely to occur.
(Iv) When a sudden increase in the ion concentration is observed, a rate of increase relative to the average value of the ion concentration observed during the two months before the sudden increase in the rapidly increased ion concentration is calculated, and the rate of increase is less than 2 times Regardless of precipitation, it is unlikely that ground displacement will occur before the next rapid increase in ion concentration is observed.

In the embodiment of the present invention, the description is based on the observation result of only one observation target ground, but actually, the observation on a plurality of observation target grounds is attempted. And it has been confirmed that the above estimation also applies to these observation target grounds.
In setting the first and second set magnifications, the calculation was performed based on the average value of the ion concentration during the two months before the ion concentration rapidly increased. However, the ion concentration is not limited to this. Appropriately depending on the actual conditions of the observation area, such as the average value of the ion concentration during the month before the sudden rise and the average value of the ion concentration from when the previous rapid rise in the ion concentration has subsided before the current sudden rise in the ion concentration It can be set.
Furthermore, in the above embodiment, the first set magnification is set to 4 times, the second set magnification is set to 2 times, and the ground displacement occurrence prediction reference in the case of an ion concentration less than the first set magnification and greater than or equal to the second set magnification is a peak. It was decided that the continuous precipitation would reach 60 mm during the three months from when the highest concentration value was observed, but it is not limited to this. It depends greatly on the environment, etc. For this reason, these values need to be obtained by actual observation in the observation area.
The first set magnification may be selected and implemented as long as it is higher than the second set magnification. Then, the set magnification may be only the first set magnification. In this case, if the set magnification is equal to or greater than the first set magnification, the possibility of occurrence of ground displacement is predicted without considering precipitation for a predetermined period. If it is (below), a continuous precipitation amount may be observed for a predetermined period from the highest peak concentration after the rapid increase in ion concentration, and the possibility of occurrence of ground displacement may be predicted based on this observation result.

The ground displacement prediction by the above ground displacement prediction method can be automatically performed by the prediction device 5 using the microcomputer shown in FIG. The prediction device 5 includes a main body 6 having a control unit having various necessary means necessary for configuring a microcomputer such as a storage unit, a calculation unit, and a determination unit, a display unit (display) 7, and an input unit (keyboard). 8 and a general-purpose one. Input of necessary information to the main body 6 may be performed artificially from the input unit 8, but may be automatically input from each measuring device via an information transmission line such as an Internet line or an aerial line.
Next, the prediction procedure will be described based on the control flow shown in FIG. First, in step 1 (S1), the first and second set magnifications N1 and N2 which are already determined ion concentration increase magnifications are counted from the day when the ion concentration suddenly increases and the maximum peak concentration is observed. The predetermined continuous precipitation M, which is set as the continuous precipitation during the predetermined period T, is input as an initial setting. Next, in step 2 (S2), an average value Xa of ion concentrations from the measured value Xn of the input groundwater ion concentration today (n days) to two months ago is calculated, and in step 3 (S3), The increase factor U of today's measured value Xn with respect to the average value Xa is calculated. Next, in step 4 (S4), it is determined whether or not the increase magnification U calculated in step 3 exceeds the second set magnification (2 times in the present embodiment) N2 (N2 <U). If it is determined, in step 5 (S5), it is determined whether or not the increase magnification U registered in step 3 is the first set magnification (four times in the present embodiment) N1 or more (U ≧ N1). If it is determined that, it is predicted that there is a high possibility that ground displacement will occur soon, and this is notified.
On the other hand, if it is determined in step 5 (S5) that the increase rate U does not exceed the first set magnification N1 (U <N1), the maximum value of the ion concentration is observed in step 6 (S6). Whether or not the continuous precipitation amount has reached the set continuous precipitation amount M (60 mm in this embodiment) input in step 1 during a predetermined period T (three months in this embodiment) from If it is determined that it has been reached, it is predicted that there is a high possibility that ground displacement will occur soon, and this is notified.
On the other hand, if the continuous precipitation does not reach the set continuous precipitation M even after the predetermined period T has elapsed, the process returns.

In this way, the first and second set magnifications, the predetermined period, and the set continuous precipitation amount are input, and the first and second are calculated by calculating the increase rate with respect to the average value of the ion concentration before the rapid increase in the observed ion concentration. Compared to two set magnifications, and based on the comparison, the continuous precipitation measured for a predetermined period and the set continuous precipitation are compared to predict the ground displacement, and for example, an alarm is issued based on the prediction, etc. By using the apparatus configured as described above, it is possible to predict the ground displacement in the observation target area with high accuracy.
Note that the numerical values of the first and second set magnifications N1 and N2, the predetermined period T, and the set continuous precipitation M that are input here are not limited to the embodiment of the present invention as described above. It can be changed as appropriate according to local conditions.

  INDUSTRIAL APPLICABILITY The present invention is used in the technical field of a ground displacement prediction method and a prediction device for predicting ground displacement that may cause landslides such as landslides, surface layer collapse, and landslides that may occur on unstable slope ground. be able to.

3 Sliding surface 4 Ground

Claims (2)

The ion concentration of specific ions present in the groundwater in the area where the ground displacement due to slope failure such as landslide and surface layer collapse is continuously measured, and the ion concentration of the specific ions changed rapidly In the prediction method that predicts that there is a possibility of ground displacement due to slope failure such as landslide and surface failure,
If there is a sudden increase in the ion concentration, calculate the increase rate relative to the average ion concentration observed before the rapid increase,
When the increase rate is higher than a preset set rate, it is predicted that there is a high possibility of occurrence of ground displacement regardless of precipitation after the rapid increase in the ion concentration,
When the increase rate is lower than the set rate, when the continuous precipitation reaches a preset set continuous precipitation during the period from the day when the rapid increase of the ion concentration is observed to the predetermined period In order to predict that there is a high possibility of ground displacement ,
When the set magnification is a first set magnification, a magnification lower than the first set magnification is set as a second set magnification, and the ion concentration increase magnification is between the first set magnification and the second set magnification, It is predicted that the possibility of ground displacement is high if the continuous precipitation reaches the preset continuous precipitation during the period from the day when the rapid rise in ion concentration is observed until the predetermined period. If it does not reach, it is predicted that the possibility of ground displacement is low, and if it is lower than the second set magnification, the possibility of ground displacement occurring regardless of the precipitation after the rapid increase in ion concentration is A method for predicting ground displacement, characterized by being predicted to be low . The ion concentration of specific ions present in the groundwater in the area where the ground displacement due to slope failure such as landslide and surface layer collapse is continuously measured, and the ion concentration of the specific ions changed rapidly In the prediction device that predicts that there may be ground displacement due to slope failure such as landslide and surface failure,
An increase factor calculating means for calculating an increase rate relative to the average ion concentration observed before the rapid increase in the case of a sudden increase in the ion concentration;
When the increase rate is higher than a preset set rate, while predicting that there is a high possibility of occurrence of ground displacement regardless of precipitation after the rapid increase of the ion concentration,
If the rate of increase is lower than the set rate, ground displacement will occur when the continuous precipitation reaches a preset set amount of precipitation during the period from the day when the sudden increase is observed until a predetermined period. With a predictor that predicts that there is a high probability of
In the prediction means, the set magnification is set as the first set magnification, and a magnification lower than the first set magnification is registered as the second set magnification. The prediction means sets the increase rate of the ion concentration to the first set magnification and the second set magnification. If it is between the set magnifications, if the continuous precipitation reaches the preset continuous precipitation during the period from the day when the rapid increase in the ion concentration is observed until the predetermined period, the ground It is predicted that the possibility of displacement is high, and if it does not reach, it is predicted that the possibility of ground displacement is low. A ground displacement prediction apparatus, which is set to predict that the possibility of occurrence of ground displacement is low regardless of the above .

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