JP5669311B2 - 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. In this way, we focused on the fact that the groundwater that passed through the surface of the finely divided soil particles had a higher ion concentration than the groundwater that passed through the relatively large soil particle surface that was not subjected to sliding force. , Continuously measure the ion concentration of groundwater into which the water that passed through the slip surface flows, and if the ion concentration increases, observe 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.

Japanese Patent No. 2847180 Japanese Patent No. 4219100

  The thing of patent document 2 is measuring the ion concentration of the groundwater which flows through the observation object site of the ground displacement continuously, and predicting the ground displacement assuming that the slip surface has occurred when the ion concentration changes suddenly. 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 higher than the first set magnification is predicted that is likely to occur in irrespective ground displacement of precipitation after spike of the ion concentration, the lower magnification than the first set magnification If set as two set magnifications, and the ion concentration increase rate is between the first set magnification and the second set magnification, it is greater than the set precipitation amount that is set in advance within a preset period after the sudden rise If precipitation is observed, it is predicted that the possibility of ground displacement is high, and if there is no precipitation more than the set amount of precipitation, it is predicted that the possibility of ground displacement is low. Is low, it is predicted that the possibility of occurrence of ground displacement is low regardless of the precipitation after the rapid increase of the ion concentration .
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 ascending rate is higher than a preset first set rate, regardless of the precipitation after the rapid increase in the ion concentration. not one to predict that there is a high possibility that the occurrence of ground displacement, and registers the lower magnification than the first set magnification as the second set magnification, increase magnification first set of ion concentration ratio and the second In the case of constant magnification, if precipitation more than the preset precipitation amount is observed within a preset period after a sudden rise, it is predicted that the possibility of ground displacement is high and the set precipitation If more precipitation than the quantity is not observed, it is predicted that the possibility of ground displacement is low, and if it is lower than the second set magnification, the occurrence of ground displacement occurs regardless of the precipitation after the rapid increase in ion concentration. The ground displacement prediction apparatus is characterized by comprising prediction means set so as to predict that the possibility of being low is low .

According to the invention of claim 1 or 2 , when the ion concentration of the specific ion of groundwater flowing through the ground of the observation target area is rapidly increased, the rate of increase of the rapidly increased ion concentration with respect to the average ion concentration before the rapid increase is obtained. It is calculated and divided into cases by comparing the calculated ascent rate with the set rate. If there is a sudden rise below the set rate, the ground displacement is predicted based on the observation result of precipitation. Therefore, it is possible to accurately predict the occurrence of ground displacement such as landslides and slope failures.

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 ion concentration and the amount of ground displacement. It is a graph which shows ion concentration, the integrated value of precipitation every 3 days, and the amount of ground displacement. It is the schematic of the microcomputer used for the ground displacement prediction apparatus. It is a control flow in the ground displacement prediction apparatus.

  In general, slope failures such as landslides and surface layer failures occur due to instability of the ground due to weathering or the like. The soil particles in the stable ground are relatively large soil particles (soil particles 1) as shown in FIG. 1, but microscopic displacement and destruction of the soil particles occur in the unstable ground. The soil particles are in a powder form (soil particles 2) smaller than the soil particles 1. In this way, the location where the soil particles become powdery changes the stress, so that the mass of the soil easily moves, and the slip surface 3 is generated here (the state shown in FIG. 2A). When such a slip surface 3 occurs, the stress of the soil block around the slip surface changes, so that the soil block begins to move to become stable (ground displacement). Due to this movement, the slip surface 3 gradually grows and spreads in the ground 4 (state shown in FIG. 2 (B)), and the entire ground moves using the grown slip surface 3 as a sliding surface to cause landslide disasters such as landslide collapse. Occurs (state shown in FIG. 2C).

  On the other hand, the rainwater that falls on the slope where the ground displacement is to be observed, when it reaches the surface of the earth, contains particles derived from sea salt and smoke-derived particles floating in the air, such as sodium ions, calcium ions, and chlorine ions. In addition, a low concentration of sulfate ions and the like is observed. The ion concentration of rainwater on the surface of the ground is used as the background concentration (see FIG. 3).

Rainwater that has fallen on the sloped land will infiltrate from the ground surface 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 generally known to perform ion exchange in For this reason, the rainwater that has permeated the ground has an ion concentration higher than the background concentration by ion exchange. This ion concentration is taken as the baseline concentration.

By the way, when the soil particles are refined, since the surface area of the soil particles increases as a whole, the number of ion exchange groups on the surface of the soil particles increases accordingly, and the groundwater that has passed through the soil particle surface in such a state is The amount of ions (ion concentration) is greater than that of groundwater that has passed between the soil particles before being refined. Thus, the ion concentration which became high by having passed between the soil particles immediately after refinement | miniaturization is made into peak concentration.
In the vicinity where the above-mentioned slip surface is generated, the soil particles are miniaturized due to friction and partial breakage, and the effective surface area of the soil particles as a whole is large. Passed groundwater has a peak concentration.

  In this way, the rainwater that falls on the sloped land undergoes ion exchange with the soil particles in the ground in the process of becoming groundwater from the surface of the sloped ground through the ground in the ground, so the ion concentration of groundwater that has passed through the observation site is If the groundwater ion concentration rises from the baseline concentration to the peak concentration as described above, reflecting the geomechanical or chemical state, a slip surface occurs at any of the observation sites. Can be guessed. It can be estimated that the higher the rate of increase of the ion concentration from the baseline concentration to the peak concentration, the larger the scale of the generated slip surface.

  However, as is apparent from the graph shown in FIG. 4, even if the ion concentration such as sodium ion or calcium ion indicating the occurrence of the slip surface rises rapidly, the ground displacement does not occur for 2 to 3 months thereafter. Therefore, it cannot be said that there is always a clear relationship between the rapid increase in ion concentration and ground displacement. In other words, although the occurrence of a slip surface is a factor in ground displacement, there is another factor different from the occurrence of a slip surface in order to cause actual ground displacement. It is reasonable to think of it as a trigger for displacement.

  If a phenomenon such as slope failure occurs even though the peak concentration was not measured, it can be considered that the groundwater being measured does not pass through the slip surface that caused the slope failure. If a slope failure occurs in a certain area, the groundwater in the area is not necessarily groundwater that has passed through the slip surface that would have caused the slope. Therefore, in order to predict the ground displacement more accurately, it is necessary to grasp the route of groundwater that passes through the slope to be observed.

  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 with a heavy rain, precipitation is a natural phenomenon that is seen more frequently than earthquakes, and groundwater flows through the ground every time it rains, affecting the ground. In particular, it is generally well known that the sudden increase in precipitation due to the stagnation of the rainy season front, typhoons, etc., triggers sediment runoff. Therefore, the inventor of the present invention examined the causal relationship between the precipitation amount in the observation target area after the occurrence of the slip surface and the subsequent occurrence of ground displacement.

The inventors of the present invention observed the relationship between the change in ion concentration, precipitation, and ground displacement in the observation target area over a long period of time, and found that the following characteristic phenomenon occurred. Discovered and completed the present invention.
(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. After that, it was confirmed that there is a high possibility that ground displacement will occur for 2 to 3 months. In such a case, even if there is no cause of a large amount of precipitation, it will slide enough to cause ground displacement alone. It is inferred that the scale of the surface was large.
(2) The rate of increase in ion concentration is not as high as in (1), but the ion concentration is rising at a higher rate compared to the ion concentration before the increase. In this case, the rate of increase in ion concentration is Although it is not as high as (1), it is presumed that a moderate-scale slip surface has occurred. In this case, if a large amount of precipitation is observed after a sharp rise in ion concentration, 2 It is confirmed that there is a high possibility that ground displacement will occur during the period up to 3 months. In such a case, the occurrence of slip surface and a large amount of precipitation are the direct factors that cause ground displacement. Inferred.
(3) When the rate of increase in ion concentration is lower than in (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.

In this way, the occurrence of ground displacement can be predicted with a high probability by measuring ion concentration and precipitation, but when predicting the occurrence of ground displacement, the rate of increase in ion concentration and precipitation The quantity varies depending on the measurement location and is not constant. Therefore, it is needless to say that specific numerical values for classification into the above (1) to (3) are determined by data observed in advance at the measurement location.
An example of observation at one location is described below, but there are a plurality of actual observation cases, and almost the same phenomenon is observed in any case.

Fig. 5 shows specific ions (sodium ion, calcium ion) obtained by continuously measuring groundwater passing through the observation ground for about 4 years from a certain observation start date in a certain area where landslide was actually observed. It is a graph which shows the ion concentration value (mg / L), the displacement amount (mm) of the ground in a specific observation point, and the integrated value (integrated amount) (mm) of precipitation every three days.
The surface ground of this area is mudstone that has been heavily weathered, and several landslides have occurred repeatedly in the past.
Inclinometer holes are excavated at two locations close to the landslide occurrence site, which is the observation target site, and the displacement of the ground displacement is measured by the inclinometers a and b installed at the innermost part of the inclinometer hole. 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.
Of the two inclinometer holes, the groundwater stored in the inclinometer hole on the mountain foot side is collected as an analysis sample. The amount collected was 100 mL (milliliter) of ground water, and was collected every two weeks and placed in a polyethylene bottle for analysis. In the analysis, ion chromatography / electric conductivity detection method was used, and the concentrations of sodium ions (Na ⁺ ) and calcium ions (Ca ²⁺ ) in the collected ground water were quantified. FIG. 5 shows the relationship between these quantified ion concentration values and the ground displacements appearing on the inclinometers a and b.

  Looking at the change in ion concentration from FIG. 5, first, when the ion concentration of sodium ion or calcium ion in groundwater is less than 100 mg / L, the baseline concentration is used, and when it is 100 mg / L or more, the peak concentration is obtained. In this case, the ion concentration showed the peak concentration in (A) March to April in the first year of observation, (B) August in the first year of observation, (C) May to 7 one year after the start of observation. Moon, (D) June to August two years after the start of observation, (E) September to November two years after the start of observation, and (F) July three years after the start of observation.

  Next, looking at the displacement of the ground, if the displacement of the ground measured by the inclinometer a (depth 7 m) or the inclinometer b (depth 3 m) is 2 mm or more, the first year of observation About 3 mm in September, about 5 mm in July one year after the start of observation, about 2 mm in September, about 2 mm in August two years after the start of observation, about 4 mm in September, August three years after the start of observation About 12 mm.

  Furthermore, looking at precipitation, if the integrated value of precipitation every three days is 100 mm or more, July, August, September in the first year of observation, June, 7 one year after the start of observation, 7 The months are July and August, two years after the start of observation.

Here, for each period of (A) to (F) when the ion concentration rapidly increased, the precipitation and the displacement of the ground after each ion concentration rapidly increased are analyzed.
(A) From March to April in the first year of observation, the ion concentration rapidly increased to exceed 100 mg / L to show the peak concentration. On March 25, the maximum peak concentration was observed. When the integrated value of precipitation every 3 days was observed from March 25 to 3 months when the maximum value of the peak concentration was observed, no precipitation exceeding 100 mm was observed. No significant ground displacement occurred during the period from when the ion concentration suddenly increased until the next ion concentration rapidly increased.
(B) From July to August in the first year of observation, the ion concentration rapidly increased to exceed 100 mg / L to show the peak concentration. On August 10, the maximum peak concentration was observed. When the integrated value of precipitation every three days was observed for three months from August 10 when the highest peak concentration was observed, precipitation exceeding 150 mm was observed on September 5. On September 7th, the ground displacement of about 3 mm was observed.
(C) One year after the start of observation, from May to July, the ion concentration rapidly increased to exceed 200 mg / L and showed a peak concentration. On June 3, the maximum peak concentration was observed. When the integrated value of precipitation every three days was observed from June 3 to 3 months when the maximum value of this peak concentration was observed, precipitation exceeding 150 mm was observed on July 10. The ground displacement of about 5 mm on July 15 and about 2 mm on September 19 was observed.
(D) From June to July two years after the start of the observation, the ion concentration rapidly increased to exceed 200 mg / L to show the peak concentration. On July 29, the maximum peak concentration was observed. When the integrated value of precipitation every three days was observed for three months from July 29 when the highest peak concentration was observed, precipitation exceeding 150 mm was observed on August 27. On August 30, the ground displacement of about 2 mm was observed, and on September 15, the displacement of the board of about 4 mm was observed.
(E) Two years after the start of observation, the ion concentration rapidly increased over 200 mg / L over two times in September and November, and the peak concentration was observed. On September 23, the maximum peak concentration was observed. . When the integrated value of precipitation every three days was observed for three months from September 23 when the highest peak concentration was observed, precipitation exceeding 100 mm was observed on November 13. However, a large ground displacement did not occur during the period from the sudden increase in ion concentration to the next rapid increase in ion concentration.
(F) From June to July three years after the start of observation, the ion concentration rapidly increased to exceed 400 mg / L to show the peak concentration. On July 4, the maximum peak concentration was observed. When the integrated value of precipitation every three days was observed for three months from July 4 when the highest peak concentration was observed, the integrated value of precipitation was recorded by October 4 after three months. No precipitation exceeding 100 mm was observed. However, on August 25, a large ground displacement of about 12 mm was observed.

As a result of analyzing these phenomena (A) to (F), the following can be said.
(I) In the phenomenon of (F), the value of the rapidly increasing ion concentration increases to four times or more of the average value of the ion concentration for two months before the ion concentration rapidly increases. In this case, after the highest peak concentration was observed, the ground displacement was about 12 mm in August, even though no precipitation exceeding 100 mm was observed in the integrated value of precipitation every 3 days for 3 months. Therefore, if the ion concentration rises rapidly, it is highly possible that ground displacement will occur regardless of the subsequent precipitation.
(Ii) In the phenomenon of (B), (C), (D), the increase rate of the ion concentration is about 2 to 4 times the average value of the ion concentration observed during the two months before the increase. It has become. Then, precipitation was observed in which the integrated value of precipitation every 3 days exceeded 100 mm during the period from the day when the highest peak concentration was observed to 3 months (for example, in the case of (B), the highest peak concentration). About 25 days after the observation, precipitation with an integrated value of precipitation every three days exceeding 100 mm is observed.) Later, ground displacement has occurred. Therefore, if the ion concentration value at which a rapid increase is observed is about 2 to 4 times the average value of the ion concentration during the two months before the rapid increase in ion concentration is observed, within the subsequent three months In addition, if precipitation with an integrated value of precipitation every 100 days reaches 100 mm, it is highly possible that ground displacement will occur.
(Iii) In the phenomenon (A), the increase rate of the rapidly increasing ion concentration is about 2 to 4 times the average value of the ion concentration observed during the two months before the increase. However, during the period from the day when the highest peak concentration was observed to the third month, no precipitation with an integrated value of precipitation exceeding 100 mm was observed every three days, and then a rapid increase in ion concentration was observed. No displacement was observed. Therefore, even if the ion concentration value at which the rapid increase is observed is about 2 to 4 times the average value of the ion concentration during the two months before the rapid increase in the ion concentration is observed, within the following three months In addition, if no precipitation with an integrated value of precipitation every 100 days reaches 100 mm, the possibility of ground displacement is low.
(Iv) In the phenomenon (E), the rate of increase of the rapidly increasing ion concentration is not more than twice the average value of the ion concentration observed during the two months before the increase. In this case, a rapid increase in the ion concentration was observed after the maximum peak concentration was observed up to 3 months, even though the total precipitation over three days exceeded 100 mm. Until then, no ground displacement was observed. Therefore, if the value of the ion concentration that has soared is lower than twice the average value of the ion concentration observed during the two months before the soaring, the occurrence of ground displacement regardless of the subsequent precipitation This is unlikely.

Based on this analysis, we found a ground displacement prediction method that predicts the occurrence of ground displacement from the measured values of ion concentration and precipitation.
(I) When the ion concentration increases rapidly, the increase rate with respect to the average value of the ion concentration observed during the two months before the increase is calculated, and when the increase rate is 4 times or more, the maximum value of the ion concentration There is a high possibility that ground displacement will occur regardless of the amount of precipitation for 3 months from the day of the observation. Here, the ascending magnification of 4 is set as the reference magnification, and this is set as the first setting magnification.
(Ii) When the ion concentration rapidly increases, the increase rate with respect to the average value of the ion concentration observed during the two months before the rapid increase is calculated, and when the increase rate is 2 times or more and less than 4 times, If precipitation with an integrated value of precipitation every three days exceeding 100 mm is observed for 3 months from the day when the highest value was observed, there is a high possibility that ground displacement will occur. Here, the ascending magnification of 2 is set as the reference magnification, and this is set as the second setting magnification.
(Iii) When the ion concentration rapidly rises, calculate the increase rate relative to the average value of the ion concentration observed during the two months before the rapid increase, and when the increase rate is 2 times or more and less than 4 times, If there is no precipitation over 100 mm of rainfall accumulated every three days during the three months from the day when the highest value was observed, the possibility of ground displacement is low.
(Iv) When the ion concentration rises rapidly, the increase rate with respect to the average value of the ion concentration observed during the two months before the increase is calculated, and when the increase rate is less than 2 times, the maximum value of the ion concentration is The possibility of ground displacement is low regardless of the precipitation for 3 months from the observed date.

From these facts, the following estimation is made.
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 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 at this level of increase of the ion concentration, a slip surface is generated that causes the displacement of the ground. It is estimated that the occurrence of ground displacement is low regardless of the precipitation after the increase of ion concentration.

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 previous month, and the average value of the ion concentration from when the previous rapid increase in ion concentration until the current rapid increase in ion concentration began It can be set.
Furthermore, in the above-described 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 3 days. Although the integrated value of precipitation for every 100 mm was used, it should be understood that these values are not limited to these values, and these values greatly depend on the environment of the observation area. These values must be obtained by actual observation in the observation area.
As long as the first set magnification is higher than the second set magnification, other magnifications may be selected and implemented. Precipitation as a ground displacement occurrence prediction criterion may be daily precipitation or every several days. May be an appropriate value according to the natural environment of the district where the ground displacement is predicted.
In addition, if the set magnification is only the first set magnification, if it is greater than or equal to the first set magnification, the possibility of ground displacement occurrence is predicted without considering precipitation, and less than the first set magnification (below) Then, it may be configured to observe the precipitation amount for a predetermined period from the peak value of the peak concentration after increasing the ion concentration and predict the possibility of occurrence of ground displacement based on the observation result.

The ground displacement prediction device 5 that predicts ground displacement by the above ground displacement prediction method can be automatically performed by a prediction device using a microcomputer shown in FIG. The prediction apparatus includes a main body 6 having a control unit having various necessary units 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. The general-purpose thing comprised by having may be sufficient. 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), first and second set magnifications N1 and N2 which are already determined ion concentration increase magnifications, a predetermined period T for counting from the day when the highest concentration of rapidly increased ion concentration is observed, During this predetermined period T, a set precipitation amount integrated value M set as an integrated value of precipitation amounts every three days 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 embodiment of the present invention) 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 equal to or greater than N1 (U ≧ N1) at the first set magnification (4 times in the embodiment of the present invention). If it is determined that it is N1 or more, 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 that the increase rate U does not exceed the first set rate N1 (U <N1), in step 6 (S6), a predetermined period T from the date when the maximum value of the ion concentration is observed. Whether the integrated value of precipitation every three days in (three months in the embodiment of the present invention) has reached the set integrated value M of precipitation every three days (100 mm in the embodiment of the present invention) 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 integrated value M of precipitation set in the predetermined period T has not been reached, the process returns.

In this way, the first and second set magnifications and the integrated value of the set precipitation are input, the increase rate for the average ion concentration is calculated from the actual measured values, and compared with the first and second set magnifications. Further, based on the comparison, the accumulated precipitation value measured and the set accumulated precipitation value are compared to predict the ground displacement, and for example, an alarm is issued based on the prediction. By using the apparatus configured as described above, it is possible to accurately predict the ground displacement at the observation target site.
It should be noted that the first and second set magnifications N1 and N2 and the set accumulated precipitation value M or the numerical value for the predetermined period T are not limited to the embodiment of the present invention as described above. However, it can be appropriately changed according to the situation of the observation target site.

  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,
When there is a sudden rise in the ion concentration, the multiplication factor for the average ion concentration observed before the sudden rise is calculated, and when the multiplication factor is higher than a preset first multiplication factor, Predicted that there is a high possibility of ground displacement regardless of precipitation after a sharp rise in ion concentration,
If a magnification lower than the first setting magnification is set as the second setting magnification, and the ion concentration increase magnification is between the first setting magnification and the second setting magnification, within a preset period after the rapid increase If more precipitation than the preset precipitation is observed, it is predicted that there is a high possibility of ground displacement, and if more precipitation than the set precipitation is not observed, there is a possibility of ground displacement. It is predicted that it is low, and if it is lower than the second set magnification, it is predicted that the possibility of occurrence of ground displacement is low regardless of the precipitation after the rapid increase in ion concentration. Displacement prediction method. 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 the preset first set rate, while predicting that there is a high possibility of ground displacement regardless of the precipitation after the rapid increase in the ion concentration,
When a magnification lower than the first set magnification is registered as the second set magnification, and the increase rate of the ion concentration is between the first set magnification and the second set magnification, within a preset period after the rapid increase If more precipitation than the preset precipitation is observed, the possibility of ground displacement is predicted to be high, and if more precipitation than the set precipitation is not observed, the possibility of ground displacement is low. A prediction means configured to predict that the possibility of ground displacement is low regardless of the precipitation after the rapid increase in the ion concentration when the prediction is lower than the second set magnification. An apparatus for predicting ground displacement, characterized in that:

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