JPH11304549A - Sediment movement detection sensor for river embankment - Google Patents
Sediment movement detection sensor for river embankmentInfo
- Publication number
- JPH11304549A JPH11304549A JP10106616A JP10661698A JPH11304549A JP H11304549 A JPH11304549 A JP H11304549A JP 10106616 A JP10106616 A JP 10106616A JP 10661698 A JP10661698 A JP 10661698A JP H11304549 A JPH11304549 A JP H11304549A
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- cable
- fiber cable
- sand
- earth
- 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.)
- Granted
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 20
- 239000013049 sediment Substances 0.000 title claims description 14
- 239000013307 optical fiber Substances 0.000 claims abstract description 106
- 239000004576 sand Substances 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 abstract description 8
- 238000006073 displacement reaction Methods 0.000 description 8
- 239000002689 soil Substances 0.000 description 6
- 238000005259 measurement Methods 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 4
- 239000011241 protective layer Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000004677 Nylon Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 229920001778 nylon Polymers 0.000 description 3
- 125000006850 spacer group Chemical group 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000005036 nerve Anatomy 0.000 description 1
- 238000000253 optical time-domain reflectometry Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B3/00—Engineering works in connection with control or use of streams, rivers, coasts, or other marine sites; Sealings or joints for engineering works in general
- E02B3/04—Structures or apparatus for, or methods of, protecting banks, coasts, or harbours
- E02B3/10—Dams; Dykes; Sluice ways or other structures for dykes, dams, or the like
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Mechanical Engineering (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Revetment (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光ファイバによる
歪み分布を用いた河川堤防の土砂移動検出センサに係
り、特に、土砂の移動を精度良く検出する河川堤防の土
砂移動検出センサに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting sediment movement of a river embankment using strain distribution caused by an optical fiber, and more particularly to a sensor for detecting sediment movement of a river embankment for accurately detecting the movement of sediment. .
【０００２】[0002]
【従来の技術】河川管理において堤防の崩壊や変形を発
見することは重要である。本出願人は、光ファイバケー
ブルを利用した分布型の歪みセンサを河川堤防に埋設
し、土砂の移動を光ファイバケーブルに生じる歪みから
検出する方法について検討しているものである。2. Description of the Related Art In river management, it is important to discover the collapse and deformation of embankments. The present applicant is studying a method of burying a distributed strain sensor using an optical fiber cable in a river embankment and detecting the movement of earth and sand from the strain generated in the optical fiber cable.
【０００３】光ファイバケーブルを利用した分布型の歪
みセンサについては、多種の特許が出願されている。そ
の中からいくつか代表的なものを述べる。Various types of patents have been filed for a distributed strain sensor using an optical fiber cable. Some typical ones are described.
【０００４】歪み検知センサ（特開平3-175328号公報）
では、光ファイバ素線を真直に張った状態で溝内に収納
する際に、所定の伸びを予め与えて光ファイバ素線に圧
縮歪みを加えることにより、低歪み量の検知を可能とす
る。[0004] Distortion detection sensor (Japanese Patent Laid-Open No. 3-175328)
Thus, when the optical fiber is stored in the groove in a state where it is stretched straight, a predetermined amount of elongation is given in advance to apply a compressive strain to the optical fiber, thereby enabling detection of a low distortion amount.
【０００５】歪み検知用センサ（特開平4-212004号公
報）では、一定周期で連続的に波状に曲げられた金属管
の中に光ファイバを収納することにより、光ファイバに
曲げを加えることができ且つ光伝送損失の変化を安定し
て検知可能とする。In a distortion detecting sensor (Japanese Patent Application Laid-Open No. H4-2212004), a bend can be applied to an optical fiber by housing the optical fiber in a metal tube that is continuously bent in a constant cycle. It is possible to stably detect a change in optical transmission loss.
【０００６】歪み測定用光ファイバケーブル（特開平7-
181021号公報）では、化学的に変化する物質をシース内
に充填することで、ケーブル敷設時は光ファイバ心線と
シースとのルース性を確保して光ファイバ心線に歪みが
加わらないようにし、敷設後は密着性が出るようにして
測定対象物の歪みを心線にそのまま伝えるようにして測
定対象物の歪みを正確に測定する。[0006] Optical fiber cable for strain measurement
No. 181021), the sheath is filled with a chemically changing substance to secure the looseness between the optical fiber core and the sheath when the cable is laid so that the optical fiber core is not strained. After the laying, the distortion of the object to be measured is accurately measured by transmitting the distortion of the object to be measured as it is so that the adhesion is obtained.
【０００７】歪み検知用センサ（実開平2-120008号公
報）では、通常の光通信用ファイバとして用いられるナ
イロン被覆をした光ファイバ心線の単にナイロン被覆を
施していないものを採用し、所定の張力状態で中心部材
に縦添えして保護層により被覆して光ファイバ素線を固
定するようにしたから、特殊な光ファイバを用いる必要
がなく、簡単に低価格で歪み測定用光ファイバケーブル
を作ることが出来る。A sensor for strain detection (Japanese Utility Model Application Laid-Open No. 2-120008) employs a nylon-coated optical fiber core wire used as a normal optical communication fiber, which is not simply coated with nylon. Since the optical fiber is fixed by covering it with a protective layer by attaching it vertically to the center member under tension, there is no need to use a special optical fiber, and an optical fiber cable for strain measurement can be easily manufactured at low cost. I can make it.
【０００８】以上が代表的な光ファイバによる分布型歪
みセンサに関する代表的な従来技術である。The above is a typical prior art related to a typical optical fiber distributed strain sensor.
【０００９】[0009]
【発明が解決しようとする課題】分布型歪みセンサを河
川堤防の土砂移動検出センサに利用するには、以下の問
題点がある。The use of a distributed strain sensor as a sensor for detecting the movement of sediment on a river embankment has the following problems.
【００１０】歪み検知用センサ（特開平3-175328号公
報）で述べられている歪みセンサ用ケーブルは、あらか
じめスペーサに０．１％程度の伸びを与えて光ファイバ
を布設する。この方法では製造工程が煩雑になり、長距
離のケーブル製造が困難である。また、スペーサと光フ
ァイバを樹脂で固定し、その後スペーサの伸びを元に戻
して光ファイバに圧縮歪みを与えるが、その際光ファイ
バに与えられる圧縮歪みは長さ方向にわたって不均一に
なる可能性があり、これでは光ファイバの長さ方向で歪
みの検出性能がばらつく結果になる。In the strain sensor cable described in the strain detection sensor (Japanese Patent Application Laid-Open No. 3-175328), an optical fiber is laid by giving a spacer about 0.1% elongation in advance. In this method, the manufacturing process is complicated, and it is difficult to manufacture a long-distance cable. In addition, the spacer and the optical fiber are fixed with resin, and then the extension of the spacer is restored to give the optical fiber a compressive strain. At that time, the compressive strain applied to the optical fiber may be non-uniform in the length direction. This results in variations in strain detection performance along the length of the optical fiber.
【００１１】歪み検知用センサ（特開平4-212004号公
報）で述べられている歪みセンサ用ケーブルは、光ファ
イバの曲げによる伝送損失の増加により歪みを検出する
ものであり、ある一点で局所的な歪みが加わった場合、
その箇所での伝送損失が大きくなり、そこから後のケー
ブルの測定が不可能になってしまう。例えば、堤防を１
０ｋｍにわたって監視する目的でこのセンサケーブルを
敷設して測定を行った場合、最初の１ｋｍのところで堤
防の変形が生じケーブルに歪みが加わると、残りの９ｋ
ｍの部分はその時点で測定不可能となり、実用性に欠け
るシステムとなる。The strain sensor cable described in the strain detection sensor (Japanese Patent Application Laid-Open No. Hei 4-212004) detects a strain due to an increase in transmission loss due to bending of an optical fiber. When a large distortion is added,
The transmission loss at that point becomes large, and it becomes impossible to measure the cable thereafter. For example, one dike
When this sensor cable is laid for the purpose of monitoring over 0 km and the measurement is performed, when the bank is deformed at the first 1 km and the cable is distorted, the remaining 9 km is applied.
The part of m cannot be measured at that time, resulting in a system lacking in practicality.
【００１２】歪み分布測定用光ファイバケーブル（特開
平7-181021号公報）で述べられている歪みセンサ用ケー
ブルでは、光ファイバ心線とシースが密着しているた
め、測定対象物の歪みが光ファイバ心線に伝わりやすい
が、充填した樹脂が硬化した後にはケーブルの剛性が増
加し、堤防に敷設した場合に周囲の土砂の動きに追随し
にくくなる可能性がある。In the strain sensor cable described in the optical fiber cable for strain distribution measurement (Japanese Patent Application Laid-Open No. Hei 7-181012), since the optical fiber core wire and the sheath are in close contact with each other, the distortion of the object to be measured is limited. Although it is easily transmitted to the fiber core wire, the rigidity of the cable increases after the filled resin is cured, and when the cable is laid on the embankment, it may be difficult to follow the movement of the surrounding earth and sand.
【００１３】歪み検知用センサ（実開平2-120008号公
報）で述べられているセンサ用ケーブルは、ナイロン被
覆していない光ファイバ心線を中心部材に縦添えし保護
層で被覆しただけのものであるが、この構造ではケーブ
ル敷設工事の際に光ファイバ心線が断線する可能性が非
常に高い。断線を防止するためには特殊な敷設工法と過
大な神経を払わなければならず、工程が煩雑になり実用
性に乏しい。The sensor cable described in the strain detection sensor (Japanese Utility Model Application Laid-Open No. 2-120008) is a cable in which an optical fiber core not coated with nylon is simply vertically attached to a central member and covered with a protective layer. However, in this structure, there is a very high possibility that the optical fiber core will be broken during the cable laying work. In order to prevent the disconnection, a special laying method and an excessive nerve must be paid, and the process becomes complicated and practicality is poor.
【００１４】歪みセンサ用ケーブルの従来技術は、 １）ケーブルに微小な曲げを与えてケーブルに加わった
歪みにより光ファイバ心線にマイクロベンドロスを与
え、そのマイクロベンドロスを光ファイバ損失測定器
（ＯＴＤＲ）で測定する方法と、 ２）ケーブル保護層と内在する光ファイバ心線とが一体
化するようにケーブル内部構造を工夫したものを使用
し、光ファイバ心線に加わる歪みを光ファイバ歪み分布
測定器で測定する方法との二つに大別できる。The prior art of a strain sensor cable is as follows: 1) A micro-bend loss is given to an optical fiber core wire by applying a slight bend to the cable and strain applied to the cable, and the micro-bend loss is measured by an optical fiber loss measuring device OTDR), and 2) using a device in which the cable inner layer is devised so that the cable protective layer and the internal optical fiber are integrated, and distorting the optical fiber with the optical fiber strain distribution. It can be broadly divided into two methods: measuring with a measuring instrument.
【００１５】光ファイバ損失測定器で測定する方法のも
のは、ある一点に歪みが加わった場合、その点で光ファ
イバ損失が増加し、残りの敷設部分を測定できないとい
う欠点がある。光ファイバ歪み分布測定器で測定する従
来の方法のものは、特に河川堤防などの土壌が比較的柔
らかい場所に敷設した場合、周辺土砂が変位または移動
してもケーブルがその移動に追随せず、周りの土砂のみ
が移動してしまい、ケーブルに歪みが加わらず、土砂の
変位または移動を検出できないという欠点がある。The method of measuring with an optical fiber loss measuring instrument has a drawback that when a distortion is applied to a certain point, the optical fiber loss increases at that point and the remaining laid portion cannot be measured. The conventional method of measuring with an optical fiber strain distribution measuring device, especially when laid in relatively soft soil such as a river embankment, the cable does not follow the movement even if the surrounding soil is displaced or moved, There is a drawback that only the surrounding earth and sand moves and no distortion is applied to the cable, so that displacement or movement of the earth and sand cannot be detected.
【００１６】そこで、本発明の目的は、上記課題を解決
し、土砂の移動を精度良く検出する河川堤防の土砂移動
検出センサを提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a sediment movement detection sensor for a river embankment which detects the movement of sediment with high accuracy.
【００１７】[0017]
【課題を解決するための手段】上記目的を達成するため
に本発明は、河川堤防の土砂中に、河川堤防に沿わせて
延出された光ファイバケーブルを埋設すると共にこの光
ファイバケーブルの側部に連結したおもりを埋設し、上
記光ファイバケーブルに加わる歪みの分布を光学的に測
定する測定器を設け、この歪み分布に基づき河川堤防の
土砂移動を検出するものである。SUMMARY OF THE INVENTION In order to achieve the above object, the present invention embeds an optical fiber cable extending along a river embankment in the soil of a river embankment, and embeds the optical fiber cable on the side of the optical fiber cable. A weight is connected to the optical fiber cable, and a measuring device for optically measuring the distribution of the strain applied to the optical fiber cable is provided, and the movement of the sediment of the river embankment is detected based on the strain distribution.
【００１８】上記おもりを上記光ファイバケーブルより
も河川堤防の法尻側に埋設してもよい。[0018] The weight may be buried at the bottom of the river embankment from the optical fiber cable.
【００１９】上記おもりを上記光ファイバケーブルから
離して埋設し、これらおもりと光ファイバケーブルとを
連結する連結部材を設けてもよい。The weight may be buried separately from the optical fiber cable, and a connecting member may be provided for connecting the weight and the optical fiber cable.
【００２０】上記おもりを上記光ファイバケーブルに装
着し、この光ファイバケーブルを河川堤防の法尻付近に
敷設してもよい。The weight may be attached to the optical fiber cable, and the optical fiber cable may be laid near the bottom of the river embankment.
【００２１】[0021]
【発明の実施の形態】以下、本発明の一実施形態を添付
図面に基づいて詳述する。An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.
【００２２】図１に示されるように、本発明の土砂移動
検出センサは、河川堤防の土砂中に、河川堤防に沿わせ
て延出された光ファイバケーブル１を埋設すると共にこ
の光ファイバケーブル１の側部に連結したおもり２を埋
設し、光ファイバケーブル１に加わる歪みの分布を光学
的に測定する歪み分布測定器３を設け、この歪み分布に
基づき河川堤防の土砂移動を検出して表示する歪み分布
表示部４を設けたものである。埋設した光ファイバケー
ブル１と歪み分布測定器３との間は、信号伝送用光ファ
イバケーブル５で接続してもよい。As shown in FIG. 1, the earth and sand movement detection sensor of the present invention embeds an optical fiber cable 1 extending along the river embankment in the earth and sand of the river embankment, The weight 2 connected to the side of the optical fiber cable 1 is buried, and a strain distribution measuring device 3 for optically measuring the distribution of strain applied to the optical fiber cable 1 is provided. This is provided with a strain distribution display section 4 that performs the following. The embedded optical fiber cable 1 and the strain distribution measuring device 3 may be connected by an optical fiber cable 5 for signal transmission.
【００２３】本発明に使用する光ファイバ心線及びその
光ファイバ心線により構成される光ファイバケーブルは
種類、形状ともに任意である。例えば、光ファイバ心線
を１つ又は複数内蔵する光ファイバケーブルであって、
光ファイバ心線を保護するための保護層で光ファイバ心
線の周囲を覆った光ファイバケーブルとする。The type and shape of the optical fiber cable used in the present invention and the optical fiber cable constituted by the optical fiber cable are arbitrary. For example, an optical fiber cable containing one or more optical fiber cores,
An optical fiber cable in which the periphery of the optical fiber core is covered with a protective layer for protecting the optical fiber core.
【００２４】また、光ファイバ心線に加わった歪みを測
定する測定器３には、光ファイバのブリルアン散乱光を
利用した光ファイバ歪み分布測定器を用いる。この光フ
ァイバ歪み分布測定器は、光ファイバに短パルスレーザ
光を入射し、光ファイバ中で散乱されるブリルアン散乱
光を検出する。ここで、入射パルス光の光周波数を可変
しながら各周波数におけるブリルアン散乱光を測定し、
ブリルアン散乱光のスペクトラム分布を測定する。この
スペクトラムの最大受光レベルとなる周波数がブリルア
ン周波数シフトとなる。ブリルアン周波数シフトのシフ
ト量と光ファイバに加わる歪みは比例関係にあることか
ら、光ファイバの長さ方向の歪み分布が得られる。光フ
ァイバに沿った距離の換算は、一般に知られているＯＴ
ＤＲ(Optical Time Domain Reflectometer) で用いられ
ている方法と同様に、レーザ測距の原理を用いる。パル
ス光を入射した際、光ファイバ中の各点から戻ってくる
散乱光は、各点からの距離に応じた長さ分だけ時間遅れ
を生じて入射端に戻ってくる。入射端に戻ってきた時間
を光の速度で除算することによりその点までの距離が分
かる。このようにして光ファイバの長さ方向の歪み分布
が得られる。As the measuring device 3 for measuring the strain applied to the optical fiber core, an optical fiber strain distribution measuring device utilizing the Brillouin scattered light of the optical fiber is used. This optical fiber strain distribution measuring instrument makes a short pulse laser beam incident on an optical fiber and detects Brillouin scattered light scattered in the optical fiber. Here, the Brillouin scattered light at each frequency was measured while varying the optical frequency of the incident pulse light,
The spectrum distribution of Brillouin scattered light is measured. The frequency at which this spectrum has the maximum light receiving level is the Brillouin frequency shift. Since the shift amount of the Brillouin frequency shift is proportional to the strain applied to the optical fiber, a strain distribution in the length direction of the optical fiber can be obtained. The conversion of the distance along the optical fiber is a commonly known OT
Similar to the method used in DR (Optical Time Domain Reflectometer), the principle of laser ranging is used. When the pulsed light is incident, the scattered light returning from each point in the optical fiber returns to the incident end with a time delay corresponding to the distance from each point. Dividing the time to return to the entrance end by the speed of light gives the distance to that point. In this way, a strain distribution in the length direction of the optical fiber is obtained.
【００２５】図２に破線で示すように、埋設したときの
光ファイバケーブルが一直線であったとする。この光フ
ァイバケーブルには一定間隔でおもりが装着されてい
る。このおもり２は、光ファイバケーブルを埋設した周
囲の土砂（土壌）が変位又は崩壊した場合に光ファイバ
ケーブル１が土砂の動きに追随しやすいようにするもの
である。おもり２を装着せず光ファイバケーブル１のみ
を敷設した場合、土砂のみが移動し、光ファイバケーブ
ル１は突っ張ってそのまま初期埋設位置を保持する可能
性が高い。As shown by the broken line in FIG. 2, it is assumed that the optical fiber cable when buried is straight. Weights are attached to the optical fiber cable at regular intervals. The weight 2 makes it easier for the optical fiber cable 1 to follow the movement of the soil when the soil (soil) surrounding the embedded optical fiber cable is displaced or collapsed. When only the optical fiber cable 1 is laid without attaching the weight 2, only the earth and sand moves, and the optical fiber cable 1 is likely to stretch and maintain the initial burying position as it is.
【００２６】おもり２の装着間隔毎に光ファイバケーブ
ル１が土砂の動きに追随して歪むと考えられるので、土
砂移動の距離分解能はおもり２の装着間隔で決定される
ことになる。Since it is considered that the optical fiber cable 1 is distorted following the movement of the earth and sand at every mounting interval of the weight 2, the distance resolution of the movement of the earth and sand is determined by the mounting interval of the weight 2.
【００２７】土砂の移動に伴っておもり２が移動した場
合に発生する光ファイバケーブル１の伸び歪みの様子を
図２に実線で図示する。光ファイバケーブル１には間隔
ｘ0でおもり２が取り付けられているものとする。この
とき中央のおもり２付近で土砂の崩壊が生じ（点線で土
砂崩壊線を示す）、おもり２が変位量ｄだけ移動し、光
ファイバケーブル１がおもり取り付け間隔でｘ1 に伸び
た場合、光ファイバケーブル１に生じる歪みｅは、 ｅ ＝（ｘ1 −ｘ0 ）／ｘ0 ={(x0 2 ＋ｄ2 ）1/2 −ｘ0 ｝／ｘ0 で与えられる。ここで、光ファイバ歪み分布測定器の最
小歪み分解能を０．０２％、おもり取り付け間隔を２ｍ
としたとき、検出可能なおもりの最小変位量ｄmin は上
式より、４ｃｍとなる。測定器の最小歪み分解能が決ま
った場合、おもりの最小変位検出量、つまりは検出可能
な土砂の最小移動量はおもり取り付け間隔によって決ま
ることがわかる。FIG. 2 shows a solid line in FIG. 2 showing how the optical fiber cable 1 is stretched and distorted when the weight 2 moves with the movement of the earth and sand. The optical fiber cable 1 is assumed to have weight 2 is attached at intervals x 0. In this case disintegration of sediment occurs in the vicinity weights 2 of the central (indicating landslides line by a dotted line), weight 2 is moved by the displacement amount d, if the optical fiber cable 1 is extended in x 1 in weight attachment interval, light The strain e generated in the fiber cable 1 is given by e = (x 1 −x 0 ) / x 0 = {(x 0 2 + d 2 ) 1/2 −x 0 } / x 0 . Here, the minimum strain resolution of the optical fiber strain distribution measuring instrument is 0.02%, and the weight mounting interval is 2 m.
, The minimum detectable displacement d min of the weight is 4 cm from the above equation. When the minimum distortion resolution of the measuring instrument is determined, it can be understood that the minimum displacement detection amount of the weight, that is, the minimum detectable amount of movement of the earth and sand is determined by the weight mounting interval.
【００２８】以上に述べたように、おもりの取り付け間
隔は土砂移動の距離分解能と検出可能最小移動量を決定
するものであるため、測定対象物によって最適な間隔を
設定する必要がある。As described above, since the weight mounting interval determines the distance resolution of the earth and sand movement and the minimum detectable movement amount, it is necessary to set an optimum interval depending on the object to be measured.
【００２９】図１の土砂移動検出センサでは、堤防の法
尻付近におもり２を装着した光ファイバケーブル１を埋
設した。この構成において、堤防に降雨を与えると共に
河川部の水位を上昇させて堤防の崩壊を促し、性能を評
価した。このとき、おもり２は２ｍ毎に装着した。前述
したように、この場合の距離分解能は２ｍ、最小土砂移
動検出量は４ｃｍである。測定器３には光ファイバ歪み
分布測定器を用い、任意の測定データの表示を行うデー
タ表示部４を設けた。In the earth and sand movement detection sensor shown in FIG. 1, an optical fiber cable 1 having a weight 2 attached is buried near the bottom of the embankment. In this configuration, rainfall was given to the embankment and the water level in the river was raised to promote the collapse of the embankment, and the performance was evaluated. At this time, the weight 2 was attached every 2 m. As described above, the distance resolution in this case is 2 m, and the minimum amount of sediment movement detection is 4 cm. As the measuring device 3, an optical fiber strain distribution measuring device was used, and a data display section 4 for displaying arbitrary measurement data was provided.
【００３０】試験開始から１１．５時間まで堤防全面に
総降雨量として１００ｍｍ／ｈの雨を降らせた。この
後、河川水位を１時間かけて２．２ｍまで上昇させ、そ
の後はこの水位を保持した。図３に堤防中央部分の光フ
ァイバケーブルで検出した歪みの経時変化を示す。ケー
ブル埋設部分は試験時間が４５時間の段階で崩壊し始め
たが、それにともなって検出した歪みが徐々に大きくな
っており、堤防の崩壊を検知できることは明白である。
さらに埋設部崩壊の１０時間程度前から、検出歪みの変
動及び微増が確認でき、堤防崩壊予知にも本発明の土砂
移動検出センサが有効であることが確認できた。A total rainfall of 100 mm / h was applied to the entire embankment for 11.5 hours from the start of the test. Thereafter, the river water level was raised to 2.2 m over one hour, and thereafter the water level was maintained. FIG. 3 shows a temporal change of the strain detected by the optical fiber cable at the center of the embankment. The cable buried portion began to collapse at the stage of the test time of 45 hours, and the strain detected thereby gradually increased, and it is clear that the collapse of the embankment can be detected.
Further, about 10 hours before the collapse of the buried portion, fluctuations and slight increases in the detected strain were confirmed, and it was confirmed that the earth and sand movement detection sensor of the present invention was also effective in predicting embankment collapse.
【００３１】上記の形態に限らず、本発明は種々の形態
が可能であることは言うまでもない。例えば、おもり２
を土砂の移動に対して抵抗を生じる形状とし、このおも
り２を抵抗が生じる配置及び姿勢で埋設する。このよう
に構成すると、土砂の移動に伴い、おもり２が移動して
光ファイバケーブル１を引っ張る。例えば、図４（ａ）
に示されるように、おもり２は棒状又は板状に形成し、
このおもり２を垂直（水平面に対して）に起立させて堤
防内に埋設する。光ファイバケーブル１は、おもり２の
下端部に位置させておく。図４（ｂ）に示されるよう
に、土砂の崩壊がおきると、おもり２は土砂移動の抵抗
になる（土砂から力を受ける）ため、光ファイバケーブ
ル１は初期の埋設位置ｙから大きく移動し、応力が加わ
る。図４（ａ）のようなおもり形状、配置、姿勢とする
ことにより比較的微小な土砂変位を検出できる。It is needless to say that the present invention is not limited to the above-described embodiment, but can be implemented in various other embodiments. For example, weight 2
Is formed into a shape that generates resistance to the movement of earth and sand, and the weight 2 is buried in an arrangement and a posture that generates resistance. With this configuration, the weight 2 moves and pulls the optical fiber cable 1 with the movement of the earth and sand. For example, FIG.
As shown in, the weight 2 is formed in a rod shape or a plate shape,
The weight 2 is erected vertically (with respect to the horizontal plane) and buried in the embankment. The optical fiber cable 1 is located at the lower end of the weight 2. As shown in FIG. 4 (b), when the collapse of the earth and sand occurs, the weight 2 becomes a resistance to the movement of the earth and sand (force is received from the earth and sand). , Stress is applied. By setting the weight shape, arrangement, and posture as shown in FIG. 4A, a relatively small displacement of the earth and sand can be detected.
【００３２】また、おもり２を光ファイバケーブル１か
ら離して堤防の法尻側に置き、おもりと光ファイバケー
ブルとは連結部材で連結してもよい。この場合、光ファ
イバケーブル１の埋設位置より下方で土砂移動が起きて
も、おもり２が移動し、光ファイバケーブル１に応力が
加わる。例えば、図５（ａ）に示されるように、おもり
２はクサビ状に形成し、このおもり２を水平に寝かせて
堤防内に埋設する。おもり２の重心部を法尻側に向け、
尖頭部を光ファイバケーブル１に向ける。このおもり２
の尖頭部と光ファイバケーブル１とを金具等の連結部材
で連結する。図５（ｂ）に示されるように、ケーブル埋
設位置よりも下方の土砂の移動とともにおもり２が移動
し、光ファイバケーブル１は初期の埋設位置ｙから大き
く移動し、応力が加わる。図５（ａ）のようなおもり形
状、配置、姿勢とすることにより、光ファイバケーブル
１の埋設位置より下方での比較的微小な土砂変位を検出
できる。Alternatively, the weight 2 may be placed on the bottom of the embankment away from the optical fiber cable 1, and the weight and the optical fiber cable may be connected by a connecting member. In this case, even if earth and sand move below the embedded position of the optical fiber cable 1, the weight 2 moves and stress is applied to the optical fiber cable 1. For example, as shown in FIG. 5A, the weight 2 is formed in a wedge shape, and the weight 2 is laid horizontally and buried in the embankment. With the center of gravity of the weight 2 facing the hips,
Point the pointed head toward the optical fiber cable 1. This weight 2
And the optical fiber cable 1 are connected by a connecting member such as a metal fitting. As shown in FIG. 5B, the weight 2 moves with the movement of the earth and sand below the cable burying position, and the optical fiber cable 1 largely moves from the initial burying position y and stress is applied. By setting the weight shape, arrangement, and posture as shown in FIG. 5A, a relatively small displacement of the earth and sand below the embedded position of the optical fiber cable 1 can be detected.
【００３３】[0033]
【発明の効果】本発明は次の如き優れた効果を発揮す
る。The present invention exhibits the following excellent effects.
【００３４】（１）土砂によっておもりが移動するの
で、確実に土砂変位を検出できる。(1) Since the weight is moved by the earth and sand, the earth and sand displacement can be reliably detected.
【００３５】（２）河川水位の上昇や地震等による堤防
の変形を検知する際に、微小な土砂変位を検出できるの
で、堤防崩壊予知にも使用できる。(2) When detecting the deformation of the embankment due to an increase in river water level or an earthquake, a minute displacement of earth and sand can be detected.
【図１】本発明の一実施形態を示す土砂移動検出センサ
の構成図である。FIG. 1 is a configuration diagram of a sediment movement detection sensor according to an embodiment of the present invention.
【図２】本発明の土砂移動検出センサの検出原理図であ
る。FIG. 2 is a detection principle diagram of the earth and sand movement detection sensor of the present invention.
【図３】本発明の動作実験における歪みの時間変化波形
図である。FIG. 3 is a time change waveform diagram of distortion in an operation experiment of the present invention.
【図４】本発明の他の実施形態を示すおもりの埋設図で
ある。FIG. 4 is an embedded view of a weight showing another embodiment of the present invention.
【図５】本発明の他の実施形態を示すおもりの埋設図で
ある。FIG. 5 is an embedded view of a weight showing another embodiment of the present invention.
１ 光ファイバケーブル ２ おもり ３ 歪み分布測定器 ４ 歪み分布表示部 DESCRIPTION OF SYMBOLS 1 Optical fiber cable 2 Weight 3 Strain distribution measuring device 4 Strain distribution display part
───────────────────────────────────────────────────── フロントページの続き (72)発明者 福地 圭介 茨城県日立市日高町５丁目１番１号 日立 電線株式会社オプトロシステム研究所内 (72)発明者 山本 哲 茨城県日立市日高町５丁目１番１号 日立 電線株式会社オプトロシステム研究所内 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keisuke Fukuchi 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Within the Opto-System Research Laboratory, Hitachi Cable, Ltd. (72) Inventor Satoshi Yamamoto Hidaka-cho, Hitachi City, Ibaraki Prefecture 5-1-1, Hitachi Cable, Ltd. Optro System Laboratory
Claims (4)
て延出された光ファイバケーブルを埋設すると共にこの
光ファイバケーブルの側部に連結したおもりを埋設し、
上記光ファイバケーブルに加わる歪みの分布を光学的に
測定する測定器を設け、この歪み分布に基づき河川堤防
の土砂移動を検出することを特徴とする河川堤防の土砂
移動検出センサ。1. An optical fiber cable extending along a river embankment is buried in earth and sand of a river embankment, and a weight connected to a side of the optical fiber cable is buried,
A sediment movement detection sensor for a river embankment, comprising a measuring device for optically measuring the distribution of strain applied to the optical fiber cable, and detecting sediment movement of the river embankment based on the strain distribution.
りも河川堤防の法尻側に埋設したことを特徴とする請求
項１記載の河川堤防の土砂移動検出センサ。2. The sensor according to claim 1, wherein the weight is buried on the side of the river embankment below the optical fiber cable.
ら離して埋設し、これらおもりと光ファイバケーブルと
を連結する連結部材を設けたことを特徴とする請求項１
又は２記載の河川堤防の土砂移動検出センサ。3. The apparatus according to claim 1, wherein said weight is buried separately from said optical fiber cable, and a connecting member for connecting said weight and said optical fiber cable is provided.
Or the sediment movement detection sensor of the river embankment described in 2.
装着し、この光ファイバケーブルを河川堤防の法尻付近
に敷設したことを特徴とする請求項１記載の河川堤防の
土砂移動検出センサ。4. The sensor according to claim 1, wherein the weight is attached to the optical fiber cable, and the optical fiber cable is laid near the bottom of the river embankment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10661698A JP3387006B2 (en) | 1998-04-16 | 1998-04-16 | Sediment movement detection sensor for river embankment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10661698A JP3387006B2 (en) | 1998-04-16 | 1998-04-16 | Sediment movement detection sensor for river embankment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11304549A true JPH11304549A (en) | 1999-11-05 |
| JP3387006B2 JP3387006B2 (en) | 2003-03-17 |
Family
ID=14438065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10661698A Expired - Fee Related JP3387006B2 (en) | 1998-04-16 | 1998-04-16 | Sediment movement detection sensor for river embankment |
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| Country | Link |
|---|---|
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6813403B2 (en) | 2002-03-14 | 2004-11-02 | Fiber Optic Systems Technology, Inc. | Monitoring of large structures using brillouin spectrum analysis |
| NL1024659C2 (en) * | 2003-10-29 | 2005-05-03 | Baas R & D B V | Earth dam condition monitoring method for e.g. dykes or embankments, uses moisture sensor |
| JP2007113991A (en) * | 2005-10-19 | 2007-05-10 | Shimizu Corp | Crack detection device and installation method thereof |
| EP1857595A1 (en) * | 2006-05-17 | 2007-11-21 | Sächsisches Textilforschungsinstitut e.V. | Use of a multi-functional, sensor-based geo textile system for dyke improvement, spatial expansion of dyke monitoring for identification of dangers in case of flood |
| CN119491471A (en) * | 2025-01-15 | 2025-02-21 | 中国水利水电第九工程局有限公司 | A dike anti-seepage treatment method based on water conservancy construction |
-
1998
- 1998-04-16 JP JP10661698A patent/JP3387006B2/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6813403B2 (en) | 2002-03-14 | 2004-11-02 | Fiber Optic Systems Technology, Inc. | Monitoring of large structures using brillouin spectrum analysis |
| NL1024659C2 (en) * | 2003-10-29 | 2005-05-03 | Baas R & D B V | Earth dam condition monitoring method for e.g. dykes or embankments, uses moisture sensor |
| JP2007113991A (en) * | 2005-10-19 | 2007-05-10 | Shimizu Corp | Crack detection device and installation method thereof |
| EP1857595A1 (en) * | 2006-05-17 | 2007-11-21 | Sächsisches Textilforschungsinstitut e.V. | Use of a multi-functional, sensor-based geo textile system for dyke improvement, spatial expansion of dyke monitoring for identification of dangers in case of flood |
| WO2007131794A3 (en) * | 2006-05-17 | 2008-03-06 | Bam | Reinforcement element with sensor fiber, monitoring system, and monitoring method |
| US8199317B2 (en) | 2006-05-17 | 2012-06-12 | Bundesanstalt für Materialforschung und -Prüfung (BAM) | Reinforcement element with sensor fiber, monitoring system, and monitoring method |
| CN119491471A (en) * | 2025-01-15 | 2025-02-21 | 中国水利水电第九工程局有限公司 | A dike anti-seepage treatment method based on water conservancy construction |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3387006B2 (en) | 2003-03-17 |
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