JP5937544B2 - Prediction method of ground displacement - Google Patents
Prediction method of ground displacement Download PDFInfo
- Publication number
- JP5937544B2 JP5937544B2 JP2013119638A JP2013119638A JP5937544B2 JP 5937544 B2 JP5937544 B2 JP 5937544B2 JP 2013119638 A JP2013119638 A JP 2013119638A JP 2013119638 A JP2013119638 A JP 2013119638A JP 5937544 B2 JP5937544 B2 JP 5937544B2
- Authority
- JP
- Japan
- Prior art keywords
- ion concentration
- amount
- ground displacement
- ground
- change
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)
Description
本発明は、斜面地盤において発生する可能性のある地すべり、表層崩壊、がけ崩れ等の土砂災害をもたらすような地盤の変位を予測する地盤変位の予測方法の技術分野に関するものである。 The present invention relates to a technical field of a ground displacement prediction method for predicting ground displacement that may cause a sediment disaster such as landslide, surface layer collapse, and landslide that may occur on slope ground.
一般に、自然災害の一つとして土砂災害があり、このような土砂災害として、傾斜地に発生する地すべり、表層崩壊、がけ崩れ、土石流などによる災害がある。そして、このような傾斜地での土砂災害は、斜面地盤が変状したり移動したりする地盤変位によって引き起される。このような地盤変位を測定する手法については、従来、例えば、地盤変位が発生するとされる場所にボーリング孔を掘り、ここに歪ゲージを備えたパイプを挿入し、地盤変位によって生じた歪量を計測することで地盤変位を測定するようにしたものが知られている（例えば、特許文献１参照。）。また、ボーリング孔に挿入されるケーブルに形状記憶合金からなる導体を内装し、地盤変位が発生した場合に導体にケーブルの変位形状を記憶させておくことで地盤変位の測定をするようにしたものも提唱されている（例えば、特許文献２参照。）。
しかしながら前記従来のものは、実際に斜面崩壊が発生している最中又は発生した後の地盤変位を測定するものであって、地盤変位の発生を予測するものではない。しかるに、地盤変位の発生を予測することは、土砂災害を未然に防止するために重要である。
そこで、本発明の発明者は、地盤変位が発生する惧れのある地区の地下水に含まれるナトリウムイオンやカルシウムイオン等の特定イオンの濃度を経時的に測定し、該イオン濃度が急激に上昇した場合には、これを地すべりや表層崩壊等の斜面崩壊による地盤変位が発生する前兆であるとして予測する方法を発明した（特許文献３参照。）。
このものは、風化の進行等により土粒子が微細化すると、地盤内の応力に変化が生じてすべり面が発生し、このすべり面が成長することによってさらにすべり面近傍の土粒子が微細化していくという現象を捉え、このように微細化した土粒子表面を通過した地下水は、摺動力を受けていない比較的大きな土粒子表面を通過した地下水よりもイオン濃度が高くなることに着目したもので、地下水に含まれるイオン濃度を継続的に測定し、イオン濃度が上昇すれば地下水が通過してきた地盤のどこかにすべり面が発生したとみなし、該すべり面が発生したことによって地盤変位が起こる可能性が高いと予測するものである。
さらに、本発明の発明者は、地盤変位が発生すると予測される地盤から供試体を採取し、該供試体に採取した現場の地下水を通過させ、該通過した地下水の化学組成の変化を観測することで、採取した地盤での地盤変位の時期を予測できることを確認し、この考え方に基づいて地盤変位の予測方法を発明した（特許文献４参照。）。
そして、これらの発明により、地盤変位の発生の予測および発生する時期を予測することができ、地盤管理に大きく貢献している。
In general, there is a landslide disaster as one of the natural disasters, and as such a landslide disaster, there are disasters caused by landslides, surface collapses, landslides, debris flows, etc. that occur on slopes. And the earth and sand disaster in such a sloping ground is caused by the ground displacement which a slope ground deforms or moves. With regard to a technique for measuring such ground displacement, conventionally, for example, a borehole is dug in a place where the ground displacement is generated, a pipe having a strain gauge is inserted therein, and the amount of strain caused by the ground displacement is calculated. What measured the ground displacement by measuring is known (for example, refer to patent documents 1). In addition, a conductor made of a shape memory alloy is built in the cable inserted into the borehole, and when the ground displacement occurs, the displacement shape of the cable is memorized in the conductor and the ground displacement is measured. Has also been proposed (see, for example, Patent Document 2).
However, the conventional one measures the ground displacement during or after the slope failure actually occurs, and does not predict the occurrence of the ground displacement. However, it is important to predict the occurrence of ground displacement in order to prevent landslide disasters.
Therefore, the inventor of the present invention measured the concentration of specific ions such as sodium ions and calcium ions contained in the groundwater in the area where the ground displacement may occur, and the ion concentration increased rapidly. In some cases, we invented a method for predicting this as a precursor to the occurrence of ground displacement due to slope failures such as landslides and surface failure (see Patent Document 3).
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 measuring the ion concentration in the groundwater, if the ion concentration increases, it is considered that a slip surface has occurred somewhere in the ground through which the groundwater has passed, and the ground displacement occurs due to the occurrence of the slip surface It is predicted that the possibility is high.
Further, the inventor of the present invention collects a specimen from the ground where ground displacement is predicted to occur, passes the groundwater collected on the specimen to the ground, and observes a change in the chemical composition of the groundwater that has passed through. Thus, it was confirmed that the ground displacement time in the collected ground could be predicted, and a ground displacement prediction method was invented based on this concept (see Patent Document 4).
And by these inventions, it is possible to predict the occurrence of ground displacement and the time when it will occur, which greatly contributes to ground management.
しかしながら、前記特許文献３、４のものは、地盤変位の発生の予測や、発生する時期を予測することはできるが、その地盤変位がどの程度の規模であるかは予測することができず、このため、具体的にどの程度の防災対策が必要であるかの判断がなかなか難しいという問題がある。そこで、本発明の発明者は、地下水中に存在する特定イオンのイオン濃度と地盤変位量とを継続的に測定して、特定イオンのイオン濃度変化量と地盤変位量との相関関係を予め求め、該相関関係に基づいて特定イオンのイオン濃度変化量から将来発生する地盤変位の変位量を予測する方法を発明した。
ところで、前述したように、地下水中の特定イオンのイオン濃度が上昇したときには地下水が通過してきた地盤のどこかにすべり面が発生したとみなすことができるので、該すべり面の発生と、すべり面の発生により引き起される地盤変位の発生とのあいだにはタイムラグが存在する。つまり、イオン濃度の上昇と地盤変位とは同時に起こるのではなく、イオン濃度の上昇の後に地盤変位が発生することになり、そこで、前記予測方法において相関関係を求めるにあたり、イオン濃度および地盤変位量の測定開始後に最初にイオン濃度の急上昇が発生したときのイオン濃度変化と、該最初のイオン濃度の急上昇の発生後に最初に発生した地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させて、イオン濃度が所定量以上変化した場合にイオン濃度変化量と地盤変位量とは一次関数の相関関係にあることを明らかにした。
しかるに、数多くの観測対象地区において前述したようにしてイオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量との相関関係を求めたところ、数少ないが、イオン濃度変化量と地盤変位量とのあいだに一次関数の相関関係が存在しない場合があることが判明した。この原因を検討したところ、前述したイオン濃度変化と地盤変位との対応に誤りがあって一次関数の相関関係にならないのではないかと考え、ここに本発明の解決すべき課題がある。
However, although the thing of the said
By the way, as described above, when the ion concentration of specific ions in the groundwater increases, it can be considered that a slip surface has occurred somewhere in the ground through which the groundwater has passed, so the occurrence of the slip surface, There is a time lag between the occurrence of ground displacement caused by the occurrence of That is, the increase in the ion concentration and the ground displacement do not occur simultaneously, but the ground displacement occurs after the increase in the ion concentration. Therefore, when obtaining the correlation in the prediction method, the ion concentration and the ground displacement amount are determined. The ion concentration change at the time when the first rapid increase in ion concentration occurs after the start of the measurement is made to correspond to the ground displacement that occurred first after the first rapid increase in ion concentration. Corresponding to the ground displacement, it was clarified that the ion concentration change amount and the ground displacement amount have a linear function correlation when the ion concentration changes more than a predetermined amount.
However, as described above, the correlation between the ion concentration change and the ground displacement was obtained by associating the ion concentration change with the ground displacement as described above in many observation target areas. It has been found that there is a case where there is no correlation between the linear function and the displacement. When this cause is examined, it is thought that there is an error in the correspondence between the ion concentration change and the ground displacement described above, and the correlation of the linear function may not be obtained, and there is a problem to be solved by the present invention.
本発明は、上記の如き実情に鑑みこれらの課題を解決することを目的として創作されたものであって、請求項１の発明は、観測対象地区の地下水中に存在する特定イオンのイオン濃度と地盤変位量とを継続的に測定し、該測定値に基づいて特定イオンのイオン濃度変化量と地盤変位量との相関関係を予め求め、該相関関係に基づいて特定イオンのイオン濃度変化量から将来発生する地盤変位の変位量を予測する予測方法であって、前記イオン濃度変化量と地盤変位量とはイオン濃度が所定量以上変化した場合に一次関数の相関関係があるとして該一次関数を求めるにあたり、イオン濃度および地盤変位量の測定開始後に最初にイオン濃度の急上昇が発生したときのイオン濃度変化と、該最初のイオン濃度の急上昇の発生後に最初に発生した地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量との相関関係を求め、該相関関係が一次関数になる場合には前記イオン濃度変化と地盤変位との対応が正しいと判断する一方、一次関数にならない場合には前記対応に誤りがあると判断して、最初のイオン濃度変化に対応させる地盤変位を２番目以降の地盤変位にずらし、該ずらした分だけ２番目以降のイオン濃度変化に対応させる地盤変位もずらす補正を行なって、イオン濃度変化量と地盤変位量との相関関係が一次関数になる対応を見いだすようにしたことを特徴とする地盤変位の予測方法である。
請求項２の発明は、請求項１において、相関関係を求める場合に用いるイオン濃度変化量は、任意のイオン濃度急上昇を今回のイオン濃度変化としたとき、該今回のイオン濃度変化の開始前の一定期間内に前回のイオン濃度変化がなかった場合には、前記一定期間におけるイオン濃度の平均値をベースライン濃度とし、また、前記一定期間内に前回のイオン濃度変化があった場合には、該前回のイオン濃度変化の終了を始点とし今回のイオン濃度変化の開始を終点とする期間におけるイオン濃度の平均値をベースライン濃度として、該ベースライン濃度を基準とする今回のイオン濃度変化時におけるイオン濃度の増加量であることを特徴とする地盤変位の予測方法である。
The present invention was created in order to solve these problems in view of the above circumstances, and the invention of
The invention according to
請求項１の発明とすることにより、タイムラグがあるイオン濃度変化と地盤変位とを、イオン濃度変化量と地盤変位量との相関関係が一次関数になるように対応させることができ、而して、前記一次関数の相関関係に基づいて将来に発生する地盤変位の規模を把握できることになって、具体的な防災対策に大いに貢献できる。
請求項２の発明とすることにより、将来発生する地盤変位の規模を正確に把握することができる。
According to the invention of
By setting it as invention of
一般に、地すべりや表層崩壊等の斜面崩壊は、風化等による地盤の不安定化に起因して発生する。そして、安定した地盤内部の土粒子は比較的大きな土粒子であるが、不安定化した地盤内部では土粒子の微視的な変位や破壊が発生しており、土粒子は小さい粒子からなる粉状になっている。このように土粒子が粉状になった箇所は応力が変化するため土塊が移動し易い状態となり、ここにすべり面が発生する。このようなすべり面が発生するとすべり面周辺の土塊の応力に変化が生じるため土塊が安定になろうとして移動し始める（地盤変位）。この移動によってすべり面は除々に成長していって地盤内に広がり、成長したすべり面を滑動面として地盤全体が移動して地すべり崩壊等の土砂災害が発生するものと考えられる。 In general, slope failures such as landslides and surface layer failures occur due to instability of the ground due to weathering or the like. Soil particles in the stable ground are relatively large soil particles, but microscopic displacement and destruction of the soil particles occur in the unstable ground, and the soil particles are powders composed of small particles. It is in the shape. In this way, the location where the soil particles become powdery changes the stress, so that the mass of the soil easily moves, and a slip surface is generated here. When such a slip surface is generated, the stress of the soil block around the slip surface changes, so that the soil block begins to move to stabilize (ground displacement). By this movement, the slip surface gradually grows and spreads in the ground, and the entire ground moves with the grown slip surface as a sliding surface, and it is considered that landslide disasters such as landslide collapse occur.
一方、地盤変位の観測対象となる傾斜地に降る雨水は、地表表面に到達した時点では海塩由来の粒子や空中に浮遊する煤煙由来の粒子等を含有し、例えばナトリウムイオン、カルシウムイオン、塩素イオン、硫酸イオン等の低濃度の含有が認められる。このような地表表面における雨水のイオン濃度をバックグラウンド濃度とする。 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 set as the background concentration.
傾斜地に降った雨水は、地表からやがて地中へと滲み込んでいき、地盤の土粒子の間を通過しながら地下水として集約されていく。
雨水を構成しているのは水であるが、水の分子は、一般に強い極性を示すことから、土粒子表面のイオン交換基（例えばシラノール基で、ケイ素原子に結合している水酸基）とのあいだでイオン交換をおこなうことが一般に知られている。このため地盤に浸透していった雨水はイオン交換がなされることによって前記バックグラウンド濃度よりも高いイオン濃度となる。このイオン濃度をベースライン濃度とする。
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 exhibit a strong polarity, and therefore, the water molecules are bonded with ion exchange groups on the surface of the soil particles (for example, silanol groups and hydroxyl groups bonded to silicon atoms). It is generally known to perform ion exchange between them. 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.
ところで、土粒子が微細化した場合は、土粒子表面積が全体として増加するため、それだけ土粒子表面のイオン交換基の数も多くなり、このような状態となった土粒子表面を通過した地下水は、微細化する前の土粒子の間を通過した地下水よりもイオンの量（イオン濃度）が多くなっている。このように微細化した直後の土粒子間を通過したことによって高くなったイオン濃度をピーク濃度とする。
前述のすべり面が発生している周辺では、摩擦や部分的な破壊によって土粒子が微細化した状態となっており、土粒子全体としての有効表面積が大きくなっているため、すべり面発生箇所を通過した地下水はピーク濃度となる。
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.
このように傾斜地に降った雨水は傾斜地の表面から地中の地盤を経て地下水となる過程で地中の土粒子とイオン交換を行うため、観測対象地盤を通過した地下水のイオン濃度は地盤中の土質力学的な、あるいは化学的な状態を反映しており、前述したように地下水のイオン濃度がベースライン濃度からピーク濃度に上昇している場合は、観測対象地盤の何れかにすべり面が発生したと推測することが出来る。そして、このイオン濃度のベースライン濃度からピーク濃度への変化量と、すべり面の発生によって引き起される地盤変位の変位量との間には相関関係が存在すると考えられ、該相関関係を求めることで、特定イオンのイオン濃度変化量から将来に発生する地盤変位の変位量を予測することができるのではないかと推論した。 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 ground to be observed 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 is generated on one of the observation grounds. Can be guessed. Then, it is considered that there is a correlation between the amount of change in the ion concentration from the baseline concentration to the peak concentration and the amount of displacement of the ground displacement caused by the occurrence of the slip surface, and the correlation is obtained. Therefore, it was inferred that the amount of ground displacement generated in the future could be predicted from the amount of ion concentration change of specific ions.
そこで、本発明の発明者は、長期に亘り、地すべりや表層崩壊等の地盤変位が発生するとされる複数の観測対象地区において、地下水中の特定イオンのイオン濃度と地盤変位量とを継続的に測定し、該測定値に基づいてイオン濃度変化量と地盤変位量との相関関係を検討した。 Therefore, the inventor of the present invention continuously determines the ion concentration and the amount of ground displacement in the groundwater in a plurality of observation target areas where a ground displacement such as a landslide or a surface layer collapse occurs over a long period of time. Based on the measured value, the correlation between the ion concentration change amount and the ground displacement amount was examined.
前記相関関係を検討するにあたり、地盤の変位量の測定は、観測対象地区の地盤に傾斜計孔を掘削し、該傾斜計孔に傾斜計を設置して地盤変位量を測定した。また、地下水中の特定イオンのイオン濃度の測定は、観測対象地区の地盤を通過する地下水を継続的に採取し、イオンクロマトグラフィー／電気伝導率検出法によりイオン濃度を測定した。濃度測定する特定イオンは無機イオンであって、カルシウムイオン、ナトリウムイオン、カリウムイオン、硫酸イオン、塩化物イオンが例示される。 In examining the correlation, the displacement of the ground was measured by excavating an inclinometer hole in the ground of the observation target area and installing an inclinometer in the inclinometer hole to measure the amount of ground displacement. In addition, the ion concentration of specific ions in groundwater was measured by continuously collecting groundwater passing through the ground in the observation target area and measuring the ion concentration by ion chromatography / electric conductivity detection method. The specific ion whose concentration is measured is an inorganic ion, and examples thereof include calcium ion, sodium ion, potassium ion, sulfate ion, and chloride ion.
さらに、前記特定イオンのイオン濃度の測定に基づいてイオン濃度の変化量を求めるが、この場合に、観測された任意のイオン濃度の急上昇を今回のイオン濃度変化としたとき、該今回のイオン濃度変化の開始前の一定期間（例えば、１〜数週間）内に前回のイオン濃度変化がなかった場合には、前記一定期間におけるイオン濃度の平均値をベースライン濃度とし、また、前記一定期間内に前回のイオン濃度変化があった場合には、該前回のイオン濃度変化の終了を始点とし今回のイオン濃度変化の開始を終点とする期間におけるイオン濃度の平均値をベースライン濃度として、該ベースライン濃度を基準とする今回のイオン濃度変化時におけるイオン濃度の増加量を、イオン濃度の変化量とする。 Further, the amount of change in the ion concentration is obtained based on the measurement of the ion concentration of the specific ion. In this case, when the sudden increase in the observed arbitrary ion concentration is taken as the current ion concentration change, the current ion concentration If there is no previous ion concentration change within a certain period (for example, 1 to several weeks) before the start of the change, the average value of the ion concentration during the certain period is set as the baseline concentration, and within the certain period When the previous ion concentration change occurred, the average value of the ion concentration over the period starting from the end of the previous ion concentration change and ending at the start of the current ion concentration change is used as the baseline concentration. The amount of increase in ion concentration at the time of the current ion concentration change based on the line concentration is defined as the ion concentration change amount.
また、前述したように、イオン濃度が急上昇した場合にはすべり面が発生したと推測されるが、該すべり面の発生と、すべり面の発生により引き起される地盤変位の発生とのあいだにはタイムラグが存在する。つまり、すべり面でイオンが地下水に溶け出した時点からさらに風化が進行してすべり面が拡大し、土塊が不安定になる大きさのすべりにまで成長するには時間を要し、また、地盤が急激に変位するには雨等のトリガーが必要であり、而して、イオン濃度の急上昇と同時に地盤変位が発生するのではなく、イオン濃度が急上昇してから時間を経て地盤変位が発生することになる。しかも、イオン濃度の急上昇から地盤変位までの時間は、地盤の特性や降水量等によって個々異なることになる。 In addition, as described above, when the ion concentration increases rapidly, it is estimated that a slip surface has occurred. Between the occurrence of the slip surface and the occurrence of ground displacement caused by the occurrence of the slip surface. There is a time lag. In other words, it takes time to grow to a size where the slip surface becomes unstable because the weathering further proceeds from the point when ions are dissolved in the groundwater on the slip surface, and the ground becomes unstable. Triggering such as rain is necessary for rapid displacement of the earth, so ground displacement does not occur at the same time as the rapid increase in ion concentration, but ground displacement occurs over time after the rapid increase in ion concentration. It will be. Moreover, the time from the sudden increase in ion concentration to ground displacement varies depending on the ground characteristics, precipitation, and the like.
そこで、イオン濃度変化量と地盤変位量との相関関係を検討する場合に、まず、イオン濃度および地盤変位量の測定開始後に最初にイオン濃度の急上昇が発生したときのイオン濃度変化と、該最初のイオン濃度の急上昇の発生後に最初に発生した地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させて相関関係を求めた。尚、以下、イオン濃度および地盤変位量の測定開始後に最初にイオン濃度の急上昇が発生したときのイオン濃度変化を最初のイオン濃度変化と称し、以降、発生順に２番目、３番目・・・のイオン濃度変化と称する。また、最初のイオン濃度の急上昇の発生後に最初に発生した地盤変位を最初の地盤変位と称し、以降、発生順に２番目、３番目・・・の地盤変位と称する。
そして、複数の観測対象地区において、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量との相関関係を検討したところ、イオン濃度の変化量が所定量未満の場合には、イオン濃度変化量と地盤変位量との間に相関関係は認められないが、イオン濃度の変化量が所定量以上の場合には、イオン濃度変化量と地盤変位量との間には一次関数の相関関係があることを発見した。
Therefore, when examining the correlation between the ion concentration change amount and the ground displacement amount, first, the ion concentration change when the ion concentration suddenly increases after the start of the measurement of the ion concentration and the ground displacement amount, Correlation was obtained by associating the first ground displacement that occurred after the sudden increase of the ion concentration and subsequently correlating the ion concentration change and the ground displacement sequentially in the order of occurrence. Hereinafter, the ion concentration change when the ion concentration suddenly increases for the first time after the start of measurement of the ion concentration and the ground displacement amount is referred to as the first ion concentration change. This is called ion concentration change. In addition, the first ground displacement that occurs after the first rapid increase in ion concentration is referred to as the first ground displacement, and is hereinafter referred to as the second, third,.
Then, in a plurality of observation target areas, the first ion concentration change and the first ground displacement are associated with each other, and the ion concentration change and the ground displacement amount are sequentially associated with each other in the order of occurrence. As a result of examining the correlation, when the amount of change in the ion concentration is less than the predetermined amount, no correlation is found between the amount of change in the ion concentration and the amount of ground displacement, but the amount of change in the ion concentration is greater than or equal to the predetermined amount. In the case of, we found that there is a linear function correlation between the ion concentration change and the ground displacement.
しかしながら、後述する測定事例４のように、前述したようなイオン濃度変化と地盤変位との対応では、イオン濃度変化量と地盤変位量との間に一次関数の相関関係が認められない場合があった。この場合に、イオン濃度変化と地盤変位との対応に誤りがあるために一次関数にならないのではないかと考え、そこで、最初のイオン濃度変化に対応させる地盤変位を２番目以降の地盤変位にずらし、該ずらした分だけ２番目以降のイオン濃度変化に対応させる地盤変位もずらす補正（再照合）を行なって、イオン濃度変化量と地盤変位量との相関関係を検討したところ、イオン濃度の変化量が所定量以上の場合には、イオン濃度変化量と地盤変位量との間に一次関数の相関関係があることを発見した。 However, as in measurement example 4 described later, in the correspondence between the ion concentration change and the ground displacement as described above, there is a case where the correlation of the linear function is not recognized between the ion concentration change amount and the ground displacement amount. It was. In this case, since there is an error in the correspondence between the ion concentration change and the ground displacement, it may be a linear function. Therefore, the ground displacement corresponding to the first ion concentration change is shifted to the second and subsequent ground displacements. Then, correction (re-verification) was performed to shift the ground displacement corresponding to the second and subsequent ion concentration changes by the amount shifted, and the correlation between the ion concentration change amount and the ground displacement amount was examined. It was discovered that there is a linear function correlation between the amount of change in ion concentration and the amount of ground displacement when the amount is greater than a predetermined amount.
つまり、イオン濃度変化量と地盤変位量との相関関係を検討するにあたり、まず、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させて相関関係を求め、該相関関係が一次関数になる場合には前記対応が正しいと判断する一方、一次関数にならない場合には前記対応に誤りがあると判断して、最初のイオン濃度変化に対応させる地盤変位を２番目以降の地盤変位にずらし、該ずらした分だけ２番目以降のイオン濃度に対応させる地盤変位もずらす補正を行なうことで、相関関係が一次関数になる対応を見いだすことができた。そして、個々の観測対象地区毎に、一次関数になる対応や、一次関数の傾き、切片を予め求めておくことで、イオン濃度変化量から将来に発生する地盤変位の変位量を予測することができると考え、本発明を完成するに至った。 In other words, when examining the correlation between the amount of ion concentration change and the amount of ground displacement, first, the first ion concentration change corresponds to the first ground displacement, and thereafter the ion concentration change and the ground displacement correspond to each other in order of occurrence. If the correlation is a linear function, the correlation is determined to be correct. If the correlation is not a linear function, the correlation is determined to be incorrect, and the first ion concentration change is determined. To find the correspondence that the correlation becomes a linear function by shifting the ground displacement to correspond to the second and subsequent ground displacements and correcting the ground displacement to correspond to the second and subsequent ion concentrations by that amount. I was able to. In addition, it is possible to predict the displacement amount of the ground displacement that will occur in the future from the amount of change in ion concentration by obtaining in advance the correspondence that becomes a linear function, the slope of the linear function, and the intercept for each observation target area. The present invention has been completed.
以下に、測定事例について具体的に説明する。
〈測定事例１〉
図２は、実際に地すべりが観測されているＡ地区において、約４年間に亘って継続的に測定した得られた、観測対象地盤を通過する地下水中に存在する特定イオン（カルシウムイオン）のイオン濃度ｐｐｍ（ｍｇ／Ｌ）と、観測対象地盤の地盤変位量（ｍｍ）とを示すグラフ図である。
このＡ地区の表層地盤は風化を強く受けた泥岩であって、過去に幾度かの地すべりが繰り返し発生している。
地盤変位量は、観測対象地盤にすべり面発生箇所を通る傾斜計孔を掘削し、該傾斜計孔内のすべり面深さ位置に傾斜計を設置して計測した。
また、特定イオンのイオン濃度を測定するにあたり、観測対象地盤を通過する地下水として前記傾斜計孔内に貯留されている地下水を採取した。採取量は地下水１００ｍＬ（ミリリットル）であり、取り決めた時間毎（測定事例１では２４時間毎）に採取してポリエチレンびんに入れ、分析を行った。分析は、イオンクロマトグラフィー／電気伝導率検出法を用い、前記採取した地下水中のカルシウムイオン（Ｃａ２＋）の濃度を定量した。そして、イオン濃度が急上昇してピーク濃度が観測された場合に、該イオン濃度急上昇を今回のイオン濃度変化として、今回のイオン濃度変化の開始前の一定期間（測定事例１では一週間）内に前回のイオン濃度変化がなかった場合には、前記一定期間におけるイオン濃度の平均値をベースライン濃度とし、該ベースライン濃度を基準として今回のイオン濃度変化時におけるイオン濃度の増加量（ピーク濃度−ベースライン濃度）を、イオン濃度変化量として求めた。また、前記一定期間内に前回のイオン濃度変化があった場合には、前回のイオン濃度変化の終了を始点とし今回のイオン濃度変化の開始を終点とする期間におけるイオン濃度の平均値をベースライン濃度とし、該ベースライン濃度を基準として今回のイオン濃度変化時におけるイオン濃度の増加量（ピーク濃度−ベースライン濃度）を、イオン濃度変化量として求めた。
そして、最初のイオン濃度変化（イオン濃度および地盤変位量の測定開始後に最初にイオン濃度の急上昇が発生したときのイオン濃度変化）と最初の地盤変位（最初のイオン濃度の急上昇の発生後に最初に発生した地盤変位）とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させて、イオン濃度変化量をＸ軸、地盤変位量をＹ軸の値としてプロットすることで、イオン濃度変化量と地盤変位量との関係を示す図３を作成した。
Below, a measurement example is demonstrated concretely.
<Measurement example 1>
Fig. 2 shows the specific ions (calcium ions) present in the groundwater passing through the observation target ground, which were continuously measured for about 4 years in the A area where landslides are actually observed. It is a graph which shows density | concentration ppm (mg / L) and the ground displacement amount (mm) of an observation object ground.
The surface ground of this A area is mudstone that has been heavily weathered, and several landslides have occurred repeatedly in the past.
The amount of ground displacement was measured by excavating an inclinometer hole that passes through the location where the slip surface occurred in the observation target ground, and installing an inclinometer at the depth of the slip surface within the inclinometer hole.
Moreover, in measuring the ion concentration of specific ions, the groundwater stored in the tilt meter hole was collected as groundwater passing through the observation target ground. The amount collected was 100 mL (milliliter) of ground water, and was collected every predetermined time (24 hours in Measurement Example 1) and placed in a polyethylene bottle for analysis. The analysis used ion chromatography / electric conductivity detection method, and the concentration of calcium ions (Ca 2+ ) in the collected ground water was quantified. Then, when the ion concentration rapidly increases and the peak concentration is observed, the ion concentration rapid increase is regarded as the current ion concentration change within a certain period (one week in the measurement example 1) before the start of the current ion concentration change. When there is no previous ion concentration change, the average value of the ion concentration during the certain period is set as the baseline concentration, and the amount of increase in the ion concentration at the current ion concentration change (peak concentration− Baseline concentration) was determined as the amount of change in ion concentration. In addition, if there is a previous ion concentration change within the predetermined period, an average value of the ion concentration in a period starting from the end of the previous ion concentration change and ending at the start of the current ion concentration change is a baseline. The amount of increase in ion concentration at the time of the current ion concentration change (peak concentration−baseline concentration) was determined as the amount of change in ion concentration.
Then, the first ion concentration change (the ion concentration change when the ion concentration first increases after the start of the measurement of the ion concentration and the ground displacement amount) and the first ground displacement (first after the first ion concentration sudden increase occurs) Generated ground displacement), and the ion concentration change and the ground displacement are sequentially matched in the order of generation, and the ion concentration change amount is plotted as the X-axis and the ground displacement amount as the Y-axis value. FIG. 3 showing the relationship between the concentration change amount and the ground displacement amount was created.
前記図３に基づいてＡ地区における特定イオン（カルシウムイオン）のイオン濃度変化量と地盤変化量との関係を検討したところ、イオン濃度の変化量が１３０ｐｐｍ未満の場合には、イオン濃度変化量と地盤変位量との間に相関関係は認められないが、イオン濃度変化量が１３０ｐｐｍ以上の場合には、イオン濃度変化量と地盤変位量とは一次関数の相関関係が存在すると推測され、そこで、イオン濃度の変化量が１３０ｐｐｍ以上の場合について回帰分析したところ、図３に示す回帰直線が得られた。この場合の決定係数Ｒ２は０．９０８８であり、強い相関関係が存在することが判明した。 Based on FIG. 3, the relationship between the ion concentration change amount of the specific ions (calcium ions) and the ground change amount in the area A was examined. When the ion concentration change amount was less than 130 ppm, the ion concentration change amount and There is no correlation between the amount of ground displacement, but when the amount of ion concentration change is 130 ppm or more, it is presumed that there is a linear function correlation between the amount of ion concentration change and the amount of ground displacement. When regression analysis was performed for a case where the amount of change in ion concentration was 130 ppm or more, a regression line shown in FIG. 3 was obtained. The coefficient of determination R 2 in this case is 0.9088, it was found that a strong correlation exists.
而して、測定事例１においては、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させた場合に、イオン濃度変化量と地盤変位量との間に一次関数の相関関係が存在し、これにより、前記イオン濃度と地盤変位との対応が正しいと判断した。 Thus, in measurement example 1, when the first ion concentration change and the first ground displacement are made to correspond, and thereafter, the ion concentration change and the ground displacement are made to correspond in order of occurrence, the ion concentration change amount and the ground There was a linear function correlation between the displacement and it was determined that the correspondence between the ion concentration and the ground displacement was correct.
〈測定事例２〉
次に、Ｂ地区において、観測対象地盤を通過する地下水中に存在する特定イオン（ナトリウムイオン）のイオン濃度ｐｐｍ（ｍｇ／Ｌ）と、観測対象地盤の地盤変位量（ｍｍ）とを約４年間に亘って継続的に測定し、該測定値に基づいて特定イオンのイオン濃度変化量と地盤変位量との相関関係を検討した。
このＢ地区は軟弱な地盤であって、斜面一帯の随所に小さな崩壊が観測されている。
地盤変位量は、前記測定事例１と同様に、観測対象地盤にすべり面発生箇所を通る傾斜計孔を掘削し、該傾斜計孔内のすべり面深さ位置に傾斜計を設置して計測した。
また、特定イオンのイオン濃度の測定は、前記測定事例１と同様に、傾斜計孔内に貯留されている地下水を採取した。採取量は地下水１００ｍＬ（ミリリットル）で、取り決めた時間毎に採取し、イオンクロマトグラフィー／電気伝導率検出法を用い、前記採取した地下水中のナトリウムイオン（Ｎａ２＋）の濃度を定量した。そして、前記測定事例１と同様にしてベースライン濃度を求め、該ベースライン濃度を基準としてイオン濃度変化時におけるイオン濃度の変化量（ピーク濃度−ベースライン濃度）を求めた。
さらに、前記図３の作成と同様にして、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量とをプロットすることにより、イオン濃度変化量と地盤変位量との関係を示す図４を作成した。
<Measurement example 2>
Next, in the B area, the ion concentration ppm (mg / L) of specific ions (sodium ions) existing in the groundwater passing through the observation target ground and the ground displacement amount (mm) of the observation target ground are about 4 years. The correlation between the ion concentration change amount of the specific ion and the ground displacement amount was examined based on the measured value.
This B area is a soft ground, and small collapses have been observed throughout the slope.
The ground displacement was measured by excavating an inclinometer hole that passes through the location where the slip surface was generated in the ground to be observed, and installing an inclinometer at the depth of the slip surface in the inclinometer hole, as in measurement example 1 above. .
Moreover, the measurement of the ion concentration of a specific ion collect | recovered the groundwater stored in the clinometer hole similarly to the said measurement example 1. FIG. The collected amount was 100 mL (milliliter) of ground water, and was collected every predetermined time, and the concentration of sodium ions (Na 2+ ) in the collected ground water was quantified using ion chromatography / electric conductivity detection method. Then, the baseline concentration was obtained in the same manner as in measurement example 1, and the amount of change in ion concentration (peak concentration−baseline concentration) at the time of ion concentration change was obtained using the baseline concentration as a reference.
Further, in the same manner as in FIG. 3, the first ion concentration change and the first ground displacement are associated with each other, and thereafter the ion concentration change and the ground displacement are sequentially associated with each other in the order of occurrence. By plotting the amount, FIG. 4 showing the relationship between the ion concentration change amount and the ground displacement amount was created.
前記図４に基づいてＢ地区における特定イオン（ナトリウムイオン）のイオン濃度変化量と地盤変化量との関係を検討したところ、イオン濃度の変化量が２００ｐｐｍ未満の場合には、イオン濃度変化量と地盤変位量との間に相関関係は認められないが、イオン濃度変化量が２００ｐｐｍ以上の場合には、地盤変位量とイオン濃度変化量とは一次関数の相関関係が存在すると推測され、そこで、イオン濃度の変化量が２００ｐｐｍ以上の場合について回帰分析したところ、図４に示す回帰直線が得られ、一次関数の相関関係が存在することが判明した。 When the relationship between the ion concentration change amount of the specific ions (sodium ions) and the ground change amount in the B area is examined based on FIG. 4, when the ion concentration change amount is less than 200 ppm, There is no correlation between the amount of ground displacement, but when the amount of ion concentration change is 200 ppm or more, it is presumed that there is a linear function correlation between the amount of ground displacement and the amount of ion concentration change. When regression analysis was performed for a case where the amount of change in ion concentration was 200 ppm or more, the regression line shown in FIG. 4 was obtained, and it was found that there was a correlation of linear functions.
而して、測定事例２においては、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させた場合に、イオン濃度変化量と地盤変位量との間に一次関数の相関関係が存在し、これにより、前記イオン濃度と地盤変位との対応が正しいと判断した。 Thus, in measurement example 2, when the first ion concentration change and the first ground displacement are made to correspond, and thereafter, the ion concentration change and the ground displacement are made to correspond in order of occurrence, the ion concentration change amount and the ground There was a linear function correlation between the displacement and it was determined that the correspondence between the ion concentration and the ground displacement was correct.
〈測定事例３〉
次に、Ｃ地区において、観測対象地盤を通過する地下水中に存在する特定イオン（硫酸イオン）のイオン濃度ｐｐｍ（ｍｇ／Ｌ）と、観測対象地盤の地盤変位量（ｍｍ）とを約４年間に亘って継続的に測定し、該測定値に基づいて特定イオンのイオン濃度変化量と地盤変位量との相関関係を検討した。
このＣ地区は、断続的に地すべりが発生している地区である。
地盤変位量は、前記測定事例１、２と同様に、観測対象地盤にすべり面発生箇所を通る傾斜計孔を掘削し、該傾斜計孔内のすべり面深さ位置に傾斜計を設置して計測した。
また、特定イオンのイオン濃度の測定は、前記測定事例１、２と同様に、傾斜計孔内に貯留されている地下水を採取した。採取量は地下水１００ｍＬ（ミリリットル）で、取り決めた時間毎に採取し、イオンクロマトグラフィー／電気伝導率検出法を用い、前記採取した地下水中の硫酸イオン（ＳＯ４ ２−）の濃度を定量した。そして、前記測定事例１、２と同様にしてベースライン濃度を求め、該ベースライン濃度を基準としてイオン濃度変化時におけるイオン濃度の変化量（ピーク濃度−ベースライン濃度）を求めた。
さらに、前記図３、４の作成と同様にして、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量とをプロットすることにより、イオン濃度変化量と地盤変位量との関係を示す図５を作成した。
<Measurement example 3>
Next, in District C, the ion concentration ppm (mg / L) of specific ions (sulfate ions) present in the groundwater passing through the observation target ground and the ground displacement (mm) of the observation target ground are about 4 years. The correlation between the ion concentration change amount of the specific ion and the ground displacement amount was examined based on the measured value.
This C area is an area where landslides occur intermittently.
As with the measurement examples 1 and 2, the ground displacement amount is obtained by excavating an inclinometer hole passing through the slip surface occurrence location on the observation target ground and installing an inclinometer at the slip surface depth position in the inclinometer hole. Measured.
Moreover, the measurement of the ion concentration of a specific ion collect | recovered the groundwater stored in the clinometer hole like the said measurement examples 1 and 2. The collected amount was 100 mL (milliliter) of ground water, and was collected every predetermined time, and the concentration of sulfate ion (SO 4 2− ) in the collected ground water was quantified using ion chromatography / electric conductivity detection method. Then, the baseline concentration was obtained in the same manner as in the measurement examples 1 and 2, and the amount of change in ion concentration (peak concentration−baseline concentration) at the time of ion concentration change was obtained using the baseline concentration as a reference.
3 and 4, the first ion concentration change and the first ground displacement are associated with each other, and thereafter the ion concentration change and the ground displacement are sequentially associated with each other in the order of occurrence. By plotting the ground displacement amount, FIG. 5 showing the relationship between the ion concentration change amount and the ground displacement amount was created.
前記図５に基づいてＣ地区における特定イオン（硫酸イオン）のイオン濃度変化量と地盤変化量との関係を検討したところ、イオン濃度の変化量が１００ｐｐｍ未満の場合には、イオン濃度変化量と地盤変位量との間に相関関係は認められないが、イオン濃度変化量が１００ｐｐｍ以上の場合には、地盤変位量とイオン濃度変化量とは一次関数の相関関係が存在すると推測され、そこで、イオン濃度の変化量が１００ｐｐｍ以上の場合について回帰分析したところ、図５に示す回帰直線が得られ、一次関数の相関関係が存在することが判明した。 Based on FIG. 5, the relationship between the ion concentration change amount of the specific ion (sulfate ion) and the ground change amount in the C area was examined. When the ion concentration change amount was less than 100 ppm, the ion concentration change amount and There is no correlation between the amount of ground displacement, but when the amount of ion concentration change is 100 ppm or more, it is presumed that there is a linear function correlation between the amount of ground displacement and the amount of ion concentration change. When regression analysis was performed for the case where the amount of change in ion concentration was 100 ppm or more, the regression line shown in FIG. 5 was obtained, and it was found that there was a correlation of linear functions.
而して、測定事例３においては、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させた場合に、イオン濃度変化量と地盤変位量との間に一次関数の相関関係が存在し、これにより、前記イオン濃度と地盤変位との対応が正しいと判断した。 Thus, in measurement example 3, when the first ion concentration change and the first ground displacement are made to correspond, and thereafter, the ion concentration change and the ground displacement are made to correspond sequentially in the order of occurrence, the ion concentration change amount and the ground There was a linear function correlation between the displacement and it was determined that the correspondence between the ion concentration and the ground displacement was correct.
〈測定事例４〉
次に、Ｄ地区において、約４年間に亘って継続的に測定した得られた、観測対象地盤を通過する地下水中に存在する特定イオン（カルシウムイオン）のイオン濃度ｐｐｍ（ｍｇ／Ｌ）と、観測対象地盤の地盤変位量（ｍｍ）とを、図６に示す。
このＤ地区は、前記測定事例１のＡ地区と同様に、風化を強く受けた泥岩であって、過去に幾度かの地すべりが繰り返し発生している。
地盤変位量は、前記測定事例１〜３と同様に、観測対象地盤にすべり面発生箇所を通る傾斜計孔を掘削し、該傾斜計孔内のすべり面深さ位置に傾斜計を設置して計測した。
また、特定イオンのイオン濃度の測定は、前記測定事例１〜３と同様に、傾斜計孔内に貯留されている地下水を採取した。採取量は地下水１００ｍＬ（ミリリットル）で、取り決めた時間毎に採取し、イオンクロマトグラフィー／電気伝導率検出法を用い、前記採取した地下水中のカルシウムイオン（Ｃａ２＋）の濃度を定量した。そして、前記測定事例１〜３と同様にしてベースライン濃度を求め、該ベースライン濃度を基準としてイオン濃度変化時におけるイオン濃度の変化量（ピーク濃度−ベースライン濃度）を求めた。
さらに、前記図３〜５の作成と同様にして、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量とをプロットして、図７を作成した。そして、該図７に基づいて、Ｄ地区における特定イオン（カルシウムイオン）のイオン濃度変化量と地盤変化量との関係を検討したところ、イオン濃度変化量と地盤変化量との間に一次関数の相関関係を見いだすことはできなかった。
<Measurement example 4>
Next, in the D district, the ion concentration ppm (mg / L) of the specific ions (calcium ions) existing in the groundwater passing through the observation target ground, which was continuously measured over about 4 years, The ground displacement amount (mm) of the observation target ground is shown in FIG.
This D area is a mudstone that has been strongly weathered like the A area of the measurement example 1, and several landslides have repeatedly occurred in the past.
As with the measurement examples 1 to 3, the ground displacement amount is obtained by excavating an inclinometer hole that passes through the slip surface occurrence location in the observation target ground and installing an inclinometer at the slip surface depth position in the inclinometer hole. Measured.
Moreover, the measurement of the ion concentration of a specific ion collect | recovered the groundwater stored in the clinometer hole similarly to the said measurement examples 1-3. The amount collected was 100 mL (milliliter) of ground water, and was collected every predetermined time, and the concentration of calcium ions (Ca 2+ ) in the collected ground water was quantified using ion chromatography / electric conductivity detection method. Then, the baseline concentration was determined in the same manner as in the measurement examples 1 to 3, and the amount of change in ion concentration (peak concentration−baseline concentration) at the time of ion concentration change was determined using the baseline concentration as a reference.
3-5, the first ion concentration change and the first ground displacement are associated with each other, and thereafter the ion concentration change and the ground displacement are sequentially associated with each other in the order of generation. FIG. 7 was created by plotting the amount of ground displacement. And based on this FIG. 7, when the relationship between the ion concentration variation | change_quantity of the specific ion (calcium ion) and ground change amount in D area was examined, a linear function is expressed between ion concentration variation | change_quantity and ground variation | change_quantity. A correlation could not be found.
そこで、前記最初のイオン濃度変化と最初の地盤変位との対応に誤りがあると判断して、最初のイオン濃度変化に対応させる地盤変位を２番目の地盤変位にずらし、２番目以降のイオン濃度変化に対応させる地盤変位も順次３番目以降の地盤変位にずらす補正を行い、該補正した対応でイオン濃度変化量と地盤変位量とをプロットして、イオン濃度変化量と地盤変位量との関係を示す図８を作成した。 Therefore, it is determined that there is an error in the correspondence between the first ion concentration change and the first ground displacement, the ground displacement corresponding to the first ion concentration change is shifted to the second ground displacement, and the second and subsequent ion concentrations are changed. The ground displacement corresponding to the change is also corrected to shift to the third and subsequent ground displacements, and the relationship between the ion concentration change amount and the ground displacement amount is plotted by plotting the ion concentration change amount and the ground displacement amount according to the corrected correspondence. FIG. 8 which shows this was created.
前記図８に基づいてＤ地区における特定イオン（カルシウムイオン）のイオン濃度変化量と地盤変化量との関係を検討したところ、イオン濃度の変化量が８０ｐｐｍ未満の場合には、イオン濃度変化量と地盤変位量との間に相関関係は認められないが、イオン濃度変化量が８０ｐｐｍ以上の場合には、地盤変位量とイオン濃度変化量とは一次関数の相関関係が存在すると推測され、そこで、イオン濃度の変化量が８０ｐｐｍ以上の場合について回帰分析したところ、図８に示す回帰直線が得られ、一次関数の相関関係が存在することが判明した。 Based on FIG. 8, the relationship between the ion concentration change amount of the specific ions (calcium ions) and the ground change amount in the D district was examined. When the ion concentration change amount was less than 80 ppm, the ion concentration change amount and There is no correlation between the amount of ground displacement, but when the amount of ion concentration change is 80 ppm or more, it is presumed that there is a linear function correlation between the amount of ground displacement and the amount of ion concentration change. When regression analysis was performed for the case where the amount of change in the ion concentration was 80 ppm or more, the regression line shown in FIG. 8 was obtained, and it was found that there was a linear function correlation.
而して、測定事例４においては、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させた場合には、イオン濃度変化量と地盤変位量との間に一次関数の相関関係が存在せず、これにより、前記イオン濃度変化と地盤変位との対応に誤りがあると判断した。そこで、最初のイオン濃度変化に対応させる地盤変位を２番目の地盤変位にずらし、２番目以降のイオン濃度に対応させる地盤変位も順次３番目以降の地盤変位にずらす補正を行なうことで、相関関係が一次関数になる対応を見いだすことができた。 Thus, in the measurement example 4, when the first ion concentration change and the first ground displacement are made to correspond, and thereafter the ion concentration change and the ground displacement are made to correspond in order of occurrence, It was determined that there was no error in the correspondence between the ion concentration change and the ground displacement because there was no linear function correlation with the ground displacement amount. Therefore, the correlation is corrected by shifting the ground displacement corresponding to the first ion concentration change to the second ground displacement and sequentially shifting the ground displacement corresponding to the second and subsequent ion concentrations to the third and subsequent ground displacements. Was found to be a linear function.
前記測定事例１〜４および実際に試みた他の複数の測定事例により、イオン濃度変化量と地盤変位量とはイオン濃度が所定量以上変化した場合に一次関数の相関関係があるとして該一次関数を求めるにあたり、まず、最初のイオン濃度変化と最初の地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量との相関関係を求め、該相関関係が一次関数になる場合には前記対応が正しいと判断する一方、一次関数にならない場合には前記対応に誤りがあると判断して、最初のイオン濃度変化に対応させる地盤変位を２番目以降の地盤変位にずらし、該ずらした分だけ２番目以降のイオン濃度変化に対応させる地盤変化もずらす補正を行なうことによって、イオン濃度変化量と地盤変位量との相関関係が一次関数になる対応を見いだすことができることが確認された。上記所定量や一次関数の傾き、切片は、個々の観測対象地盤の特性や、イオン濃度を測定する特定イオンの種類によって異なるため、各観測対象地盤毎に相関関係を予め求めておく。そして、該相関関係に基づいて、イオン濃度が所定量以上変化した場合に、該イオン濃度変化量から将来に発生する地盤変位の変位量を予測することができる。これにより、将来に発生する地盤変位の規模を正確に把握できることになり、具体的な防災対策に大いに貢献できる。 According to the measurement examples 1 to 4 and a plurality of other measurement examples actually tried, it is assumed that the ion concentration change amount and the ground displacement amount have a linear function correlation when the ion concentration changes by a predetermined amount or more. First, the first ion concentration change is associated with the first ground displacement, and thereafter, the correlation between the ion concentration change amount and the ground displacement amount is correlated with the ion concentration change and the ground displacement in order of occurrence. If the correlation is a linear function, it is determined that the correspondence is correct. If the correlation is not a linear function, it is determined that the correspondence is incorrect, and the ground displacement corresponding to the first ion concentration change is determined. Is shifted to the second and subsequent ground displacements, and the amount of change in the ion concentration and the ground displacement are corrected by shifting the ground change corresponding to the second and subsequent ion concentration changes by the amount of the displacement. Correlation with it has been confirmed that it is possible to find corresponding to become a linear function. Since the predetermined amount, the slope of the linear function, and the intercept vary depending on the characteristics of the individual observation target ground and the type of specific ions for measuring the ion concentration, the correlation is obtained in advance for each observation target ground. Based on the correlation, when the ion concentration changes by a predetermined amount or more, the displacement amount of the ground displacement that will occur in the future can be predicted from the ion concentration change amount. This makes it possible to accurately grasp the scale of ground displacement that will occur in the future, and can greatly contribute to specific disaster prevention measures.
尚、前述したように、すべり面の発生によるイオン濃度の上昇と、すべり面の発生により引き起される地盤変位の発生とのあいだにはタイムラグがあり、このため、イオン濃度変化量と地盤変位量との相関関係に基づいて、イオン濃度変化量から将来に発生する地盤変位の変位量を予測できることになるが、この場合に、地盤変位が発生する有力なトリガーとして降水が考えられる。而して、観測対象地区の降水量（時間あたりの降水量、所定期間内における積算降水量、所定期間内における連続降水量等）を観測し、該降水量が所定量以上の場合に、前記相関関係に基づいて予測した地盤変位量での地盤変位が発生する可能性が高いと予測することができる。 As described above, there is a time lag between the increase in ion concentration due to the occurrence of a slip surface and the occurrence of ground displacement caused by the occurrence of a slip surface. Based on the correlation with the amount, the amount of displacement of the ground displacement that will occur in the future can be predicted from the amount of change in the ion concentration. In this case, precipitation is considered as a powerful trigger for the occurrence of ground displacement. Thus, when the amount of precipitation in the observation target area (precipitation per hour, accumulated precipitation within a predetermined period, continuous precipitation within a predetermined period, etc.) is observed, It can be predicted that there is a high possibility that ground displacement will occur at the ground displacement amount predicted based on the correlation.
また、観測対象地盤毎にイオン濃度変化量と地盤変位量との相関関係を求めるにあたり、正確な回帰直線を作成するにはデータ数が多い方が望ましいが、前述したように複数の観測事例により強い相関関係が存在していることが判明しているため、新たな観測対象地盤で相関関係を求めるにあたり、データ数が少なくても誤差は少ないと考えられる。また、新たな観測対象地盤で相関関係を求めるには長期に亘る観測が必要であることから、多少の誤差を考慮した上で、既に相関関係を求めてある似たような特性の地盤のものを代用することもできる。 In addition, in order to obtain the correlation between the ion concentration change amount and the ground displacement amount for each observation target ground, it is desirable to have a large number of data to create an accurate regression line. Since it has been found that a strong correlation exists, it is considered that there is little error even when the number of data is small when obtaining the correlation in the new observation target ground. In addition, since long-term observation is necessary to obtain the correlation in the new observation target ground, after considering some errors, the ground of similar characteristics for which correlation has already been obtained. Can be substituted.
本発明は、不安定な斜面地盤において発生する可能性のある地盤変位の変位量を予測する場合に利用することができる。 The present invention can be used for predicting the amount of ground displacement that may occur on unstable slope ground.
Claims (2)
前記イオン濃度変化量と地盤変位量とはイオン濃度が所定量以上変化した場合に一次関数の相関関係があるとして該一次関数を求めるにあたり、
イオン濃度および地盤変位量の測定開始後に最初にイオン濃度の急上昇が発生したときのイオン濃度変化と、該最初のイオン濃度の急上昇の発生後に最初に発生した地盤変位とを対応させ、以降は発生順に順次イオン濃度変化と地盤変位とを対応させてイオン濃度変化量と地盤変位量との相関関係を求め、該相関関係が一次関数になる場合には前記イオン濃度変化と地盤変位との対応が正しいと判断する一方、一次関数にならない場合には前記対応に誤りがあると判断して、最初のイオン濃度変化に対応させる地盤変位を２番目以降の地盤変位にずらし、該ずらした分だけ２番目以降のイオン濃度変化に対応させる地盤変位もずらす補正を行なって、イオン濃度変化量と地盤変位量との相関関係が一次関数になる対応を見いだすようにしたことを特徴とする地盤変位の予測方法。 Continuously measure the ion concentration and ground displacement of specific ions present in the groundwater of the observation area, and obtain the correlation between the ion concentration change of the specific ions and the ground displacement based on the measured values. , A prediction method for predicting a displacement amount of a ground displacement that will occur in the future from an ion concentration change amount of a specific ion based on the correlation,
In obtaining the linear function, the ion concentration change amount and the ground displacement amount are correlated with a linear function when the ion concentration changes by a predetermined amount or more.
The ion concentration change when the ion concentration first increases after the start of the measurement of the ion concentration and the ground displacement amount is associated with the ground displacement first generated after the first ion concentration sudden increase occurs, and thereafter The correlation between the ion concentration change and the ground displacement is obtained by sequentially correlating the ion concentration change and the ground displacement in order, and when the correlation is a linear function, the correspondence between the ion concentration change and the ground displacement is On the other hand, if it does not become a linear function, it is determined that there is an error in the correspondence, and the ground displacement corresponding to the first ion concentration change is shifted to the second and subsequent ground displacements. Corrections were also made to shift the ground displacement corresponding to the ion concentration change after the first, so that the correlation between the ion concentration change amount and the ground displacement amount became a linear function. Prediction method of ground displacement, characterized in.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013119638A JP5937544B2 (en) | 2013-06-06 | 2013-06-06 | Prediction method of ground displacement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013119638A JP5937544B2 (en) | 2013-06-06 | 2013-06-06 | Prediction method of ground displacement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2014237933A JP2014237933A (en) | 2014-12-18 |
| JP5937544B2 true JP5937544B2 (en) | 2016-06-22 |
Family
ID=52135285
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2013119638A Expired - Fee Related JP5937544B2 (en) | 2013-06-06 | 2013-06-06 | Prediction method of ground displacement |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5937544B2 (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4219100B2 (en) * | 2001-05-18 | 2009-02-04 | 財団法人鉄道総合技術研究所 | Prediction device for ground displacement due to slope failure such as landslide and surface layer failure |
| JP2003279561A (en) * | 2002-03-26 | 2003-10-02 | Railway Technical Res Inst | Prediction method and prediction device for ground displacement |
| JP5669311B2 (en) * | 2011-03-31 | 2015-02-12 | 公益財団法人鉄道総合技術研究所 | Method and apparatus for predicting ground displacement |
| JP5718186B2 (en) * | 2011-08-01 | 2015-05-13 | 公益財団法人鉄道総合技術研究所 | Method and apparatus for predicting ground displacement |
| JP5898639B2 (en) * | 2013-03-27 | 2016-04-06 | 公益財団法人鉄道総合技術研究所 | Prediction method of ground displacement |
-
2013
- 2013-06-06 JP JP2013119638A patent/JP5937544B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2014237933A (en) | 2014-12-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Andersen et al. | Numerical modeling of salt‐water intrusion at Hallandale, Florida | |
| Rockwell et al. | Palaeoseismology of the Vilariça segment of the Manteigas-Bragança fault in northeastern Portugal | |
| Quirk et al. | Termination II, last glacial maximum, and lateglacial chronologies and paleoclimate from Big Cottonwood Canyon, Wasatch Mountains, Utah | |
| JP5669311B2 (en) | Method and apparatus for predicting ground displacement | |
| Okamoto et al. | The response of pore water pressure to snow accumulation on a low-permeability clay landslide | |
| CN106383368B (en) | Calculation method of sediment horizontal extension distance | |
| JP5898639B2 (en) | Prediction method of ground displacement | |
| Wang et al. | Channel profile response to abrupt increases in mountain uplift rates: Implications for Late Miocene to Pliocene acceleration of intracontinental extension in the northern Qinling range-Weihe graben, central China | |
| JP5669313B2 (en) | Method and apparatus for predicting ground displacement | |
| JP5937544B2 (en) | Prediction method of ground displacement | |
| JP5718186B2 (en) | Method and apparatus for predicting ground displacement | |
| Carlton et al. | Geohazard assessment related to submarine instabilities in Bjørnafjorden, Norway | |
| Conway et al. | Submarine slope failures and tsunami hazard in coastal British Columbia: Douglas Channel and Kitimat Arm | |
| Åhnberg et al. | Strength degradation of clay due to cyclic loadings and enforced deformation | |
| JP2003279561A (en) | Prediction method and prediction device for ground displacement | |
| Sroka et al. | Subsidence prediction caused by the oil and gas development | |
| JP5781820B2 (en) | Method and apparatus for predicting ground displacement | |
| Löfroth et al. | Mapping of quick clay using sounding methods and resistivity in the Göta River valley | |
| CN116933535B (en) | Geological disaster displacement monitoring method, device, equipment and storage medium | |
| Szostak-Chrzanowski et al. | Relation between monitoring and design aspects of large earth dams | |
| JP5188458B2 (en) | Method and apparatus for predicting ground displacement | |
| Apostolopoulos et al. | The electrical resistivity method—a useful tool in evaluating geological and geotechnical conditions for constructing and engineering projects | |
| Lunina et al. | Late Cenozoic fault pattern and stress fields in the Barguzin rift (Baikal region) | |
| JP5779972B2 (en) | Soil sensor and soil sensing method | |
| HOTTA et al. | Evaluation of Slip Surface Strength of a Pseudo-Slip Surface Created by Cutting Rock Samples |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20150716 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20160425 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20160428 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20160512 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 5937544 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| LAPS | Cancellation because of no payment of annual fees |