JP4114512B2

JP4114512B2 - Reservoir sand discharging method and sand discharging device

Info

Publication number: JP4114512B2
Application number: JP2003061380A
Authority: JP
Inventors: 敬一西村
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 2003-03-07
Filing date: 2003-03-07
Publication date: 2008-07-09
Anticipated expiration: 2023-03-07
Also published as: JP2004270256A

Description

【０００１】
【発明の属する技術分野】
本発明は、ダム湖等の貯水池の堆積土砂を排出するための貯水池の排砂方法及び排砂装置に関するものである。
【０００２】
【従来の技術】
近年、ダムが予想を上回る速さで土砂に埋まり、総貯水量１００万立方メートル以上の中規模ダム７８２ダムのうち、４４ダムはすでに貯水池の半分以上が堆積土砂によって埋まっていることが、国土交通省の調査によって報告されている。
【０００３】
そのため、ダム湖等の貯水池の堆積土砂を排出して、ダム建設時の貯水量に回復させることが重要な課題となっている。
【０００４】
そこで、従来では、以下に示すような種々の排砂方法が採用されていた。
【０００５】
（Ａ）グラブバケットによる浚渫方法
この方法は、台船から吊り下げたグラブバケットで堆積土砂（堆砂）を掴み上げ、その堆砂を土砂運搬船或いはスラリ輸送により別の場所に輸送する方法である。
【０００６】
（Ｂ）吸引管による浚渫方法
この方法は、台船或いは専用船から水底に吸引管を降ろし、吸引管にて堆砂を吸い込み、その堆砂を土砂運搬船或いはスラリ輸送により別の場所に輸送する方法である。
【０００７】
（Ｃ）排砂ゲートによる排砂方法
この方法は、ダム堤体の計画堆砂面よりも下方に、予め排砂管を設置すると共にその排砂管に排砂ゲートを設けておき、堆積土砂が計画堆砂面よりも高くなったなら、排砂ゲートを開け、貯水の排水と共に堆砂を排砂管を通して下流に排出する方法である。
【０００８】
（Ｄ）掃流排砂方法
この方法は、貯水池の水位を下げて、貯水池内に河川と同様の流れを作り出し、その掃流作用を利用して、ダム堤体に予め設置された排砂管、排砂ゲートを通して堆砂を下流に運搬する方法である。
【０００９】
しかしながら、上述の排砂方法は、以下に示すような問題がある。
【００１０】
（Ａ）のグラブバケットによる浚渫方法では、グラブバケットを上げ下ろしながら排砂するため、排砂効率が悪く、また、堆砂をグラブバケットで直接掴んで持ち上げるため、濁水の発生量が大きく、さらに台船を移動しながら浚渫する必要があるため作業手間がかかるといった問題があった。
【００１１】
（Ｂ）の吸引管による浚渫方法では、連続的に排砂できるため、（Ａ）のグラブバケットによる浚渫方法に比べて効率は良いものの、吸引管で直接堆積土砂を吸引するため、土砂中に流木などの異物が含まれている場合には、吸引管がその異物を吸い込むことが避けられず、このため、吸引管内に異物が詰まって作業が中断してしまうといった問題があった。また、吸引管による直接吸引では、狭い範囲でしか土砂を吸引できず、グラブバケットと同様に台船を移動させながらの浚渫となってしまう。
【００１２】
（Ｃ）の排砂ゲートによる排砂方法では、排砂管に流れる堆積土砂は、その排砂管近傍の堆砂に限られ、貯水池の広い範囲での排砂を行うことができない問題があると共に、排砂管内に異物が詰まる問題がある。また、排砂ゲートを一旦開けると堆砂がゲートに噛み込む等の弊害が生じて、閉じることができない虞があるため、現実にはほとんど実施されていない問題があった。
【００１３】
（Ｄ）の掃流排砂方法では、貯水池内に河川と同様の流れを作り出すには、貯水を全量流す必要があり、ダム本来の貯水機能がなくなるので、宇奈月ダムや出平ダムのように水位回復の早いダムでないと実施できない問題があった。
【００１４】
【特許文献１】
特開平８−１３４５３号公報
【００１５】
【発明が解決しようとする課題】
上記の（Ａ）〜（Ｄ）の方法のうち、本出願人は、（Ｃ）の排砂ゲートによる排砂方法に着目し、より広い範囲の堆積土砂を排砂でき、しかも異物の詰まりが生じないようにした排砂方法を提案（特願２００２−０６２１５７号）した。
【００１６】
この先願の方法は、排砂管廻りの堆積土砂の表面を、不透水性の遮水部材で覆い、その状態で排砂管に設けた排砂ゲートを開くことで、排砂管に流水を流し、これによりその流水と共に土砂を排砂管から流すようにしたものである。この排砂方法では、遮水部材に水圧が直接作用してその下方の堆積土砂を水圧で押さえるため、排砂管に流入する土砂は排砂管に向かう水流で運ばれる比較的粒径の小さな土砂であり、径の大きな異物は遮水部材で押さえられて移動できないため、異物による詰まりを解決でき、しかも遮水部材で覆った範囲の堆積土砂を排砂できるといった優れた効果を有する。
【００１７】
しかしながら、上述の排砂方法では、排砂開始時に排砂管が堆積土砂に埋まっており、そのため排砂ゲートを開けると、排砂管に接した堆積土砂層がその内圧によって崩壊し、非常に濃度の高い土砂流が、排砂管を流下する。従って、その下流では、非常に大きな圧力変動を伴うので、排砂管や排砂ゲート等の設備が破損する虞がある。また、排砂管の設置の無いダムについては使用できないという問題もある。
【００１８】
さらに、この排砂方法では、ダム堤体に予め設けた排砂管及び排砂ゲートを使用しているため、異物の噛み込みが無いものの、万一、土砂が排砂ゲートに流れ込み、排砂ゲートが閉まらなくなる虞れが依然としてあり、現実的な実施に問題を残している。
【００１９】
そこで、本発明は上記問題を解決するために案出されたものであって、先願の発明を改良し、排砂ゲートを用いずに排砂が行え、しかも貯水池の全体に亘って排砂できる貯水池の排砂方法及び排砂装置を提供することを目的とする。
【００２０】
【課題を解決するための手段】
本発明は、上記目的を達成するために、ダム湖等の貯水池に堆積する土砂に可撓性を有するシート状部材を敷設すると共に、そのシート状部材の中心に排砂管を接続し、その排砂管よりシート状部材内を、形成される水流と共に吸引して排砂管より水と共にダム堤体外に排砂する排砂方法であって、上記排砂管の吸引口の先端にフランジを形成し、上記シート状部材を円形、多角形状或いは楕円形に形成すると共に、シート状部材の周縁部にシート状部材の浮き上がりを防止するためのチェーンをリング状に取り付け、上記シート状部材にその裏面側に臨ませて上記排砂管の吸引口を接続し、上記堆積された土砂の表面に、これに沿って上記堆積土砂を覆うシート状部材を敷設してシート状部材の裏面部より上記堆積土砂に上記排砂管の吸引口を臨ませると共に、排砂管の排出口を、貯水池の堤体を越えさせて上記貯水池の水位よりも低い位置に配置し、サイホン現象により上記シート状部材の裏面部の堆積土砂を吸引排砂するようにした貯水池の排砂方法である。
【００２１】
上記方法によれば、堆積土砂の表面を覆ってシート状部材を敷設し、そのシート状部材の裏面部より上記堆積土砂に上記排砂管の吸引口を臨ませて、吸引排砂するようにしたので、シート状部材と堆積土砂との間に水流を作ることができ、これによる掃流作用で、堆積土砂を広い範囲から効率的に吸引することができる。また、排砂ゲートを必要としないので、排砂ゲートを備えていないダムでも適用できると共に、排砂管及び排砂ゲートが詰まる心配もない。
【００２２】
そして、ダム湖等の貯水池に堆積する土砂に可撓性を有するシート状部材を敷設すると共に、そのシート状部材の中心に排砂管を接続し、その排砂管よりシート状部材内を、形成される水流と共に吸引して排砂管より水と共にダム堤体外に排砂する排砂方法であって、上記排砂管の吸引口の先端にフランジを形成し、上記シート状部材を円形、多角形状或いは楕円形に形成すると共に、シート状部材の周縁部にシート状部材の浮き上がりを防止するためのチェーンをリング状に取り付け、上記堆積された土砂の表面に、これに沿って上記堆積土砂を覆うシート状部材を敷設し、該シート状部材にその裏面側の堆積土砂に臨ませて上記排砂管の吸引口を接続すると共に、排砂管の排出口を、貯水池の堤体を越えさせて上記貯水池の水位よりも低い位置に配置し、サイホン現象により上記シート状部材の裏面部の堆積土砂を吸引排砂するようにした貯水池の排砂方法である。
【００２３】
これによれば、サイホンは無重力で水流を得られるので経済的である。
【００２４】
また、本発明は、ダム湖等の貯水池に堆積する土砂に可撓性を有するシート状部材を敷設すると共に、そのシート状部材の中心に排砂管を接続し、その排砂管よりシート状部材内を、形成される水流と共に吸引して排砂管より水と共にダム堤体外に排砂する排砂装置であって、上記排砂管の吸引口の先端にフランジを形成し、上記シート状部材を円形、多角形状或いは楕円形に形成すると共に、シート状部材の周縁部にシート状部材の浮き上がりを防止するためのチェーンをリング状に取り付け、上記シート状部材にその裏面側に臨ませて上記排砂管の吸引口を接続して上記シート状部材の裏面部の堆積土砂を吸引排砂するように構成した貯水池の排砂装置である。
【００２７】
【発明の実施の形態】
以下、本発明の好適な実施の形態を添付図面に基づいて説明する。
【００２８】
図１に示すように、ダムの貯水池２は、川をダム堤体（堤体）１４により堰き止めて形成されている。
【００２９】
ここで、浚渫を行う貯水池２の底部に堆積している堆積土砂３は、上流から流されてきた土砂がダム堤体１４によって堰き止められて長年に亘って堆積したものである。
【００３０】
堆積土砂３は、様々な粒径の砂等からなり、その堆積土砂３中には、異物である流木や巨礫が混入している。
【００３１】
堆積土砂３を排砂するに際しては、まず、十分な敷設面積を有するシート状部材５を、浚渫すべき堆積土砂３の表面４に敷設する。
【００３２】
このシート状部材５は、不透水性或いは難透水性の布、樹脂或いはゴム等によって形成され、堆積土砂３の表面４に追従できる柔軟性と、水中で浮かずに沈む性質とを有している。シート状部材５は、上記布、樹脂或いはゴム等に、メッシュ状の補強材を設けて形成したものであってもよい。
【００３３】
シート状部材５の形状は、円形或いは多角形状とし、その直径は、後述する水流が作用する範囲とシート状部材５による堆積土砂３を押さえてシールする範囲を考慮して約１００ｍ程度に形成するのがよいが、数１０〜百数十ｍの範囲のものが使用できる。
【００３４】
なお、シート状部材５の形状は、円形或いは多角形状に限られるものではなく、楕円形等のように中心から各周縁部までの距離が大きく異ならない形状であればよい。
【００３５】
シート状部材５の敷設は、具体的には、まず、シート状部材５を、貯水池２上に浮かべた台船１５に畳まれた状態で載せ、これを畳んだ状態のままで水底の目標位置まで沈め、その水底部で広げて敷設する。なお、シート状部材５を水面近くで広げて、その状態で徐々に沈めるようにしてもよい。
【００３６】
また、シート状部材５の周縁部８には、当該シート状部材５が水流等による浮き上がりを防止するためのウエイト９が取り付けられる。ウエイト９は、シート状部材５の周縁部８全周に沿って設けられたチェーン等のリング状でかつ可撓性を有するもので構成し、敷設時に、堆積土砂３の表面形状に応じて変形して、シート状部材５の周縁部８を堆積土砂３にウエイト９の自重で押しつけるものがよい。
【００３７】
なお、ウエイト９の例として、チェーンをリング状にしたものを説明したが、本発明は、これに限られるものではなく、シート状部材５の周縁部８に沿って間隔を置いて錘を取り付けて構成してもよい。
【００３８】
このシート状部材５の中央には、排砂穴６が形成され、排砂管７が、その吸引口１１がシート状部材５の排砂穴６を通して、シート状部材５の表面部から裏面部の堆積土砂３に臨むように接続される。
【００３９】
排砂管７は、可撓性のある樹脂管からなり、その直径は、排砂効率を考慮して大きいものが好ましいが、作業性を考慮して約３００ｍｍ程度のものが好ましい。なお、排砂管７は、樹脂管だけでなく一部鋼管を使用してもよい。
【００４０】
この排砂管７の接続は、シート状部材５の敷設前に、予め接続しても、敷設後に接続しても何れでもよい。シート状部材５と排砂管７の接続は、排砂管７の先端にフランジ１６（図５参照）を形成しておき、またシート状部材５の排砂穴６に予めフランジ１６を取り付ける受け座（図示せず）を形成し、フランジ１６をシート状部材５の受け座の上側に設置して、ボルト・ナットなどにより接続する。
【００４１】
排砂管７は、その長さが、貯水池２の水深と、浚渫位置上の水面からダム堤体１４までの距離と、ダム堤体１４の上面から貯水池２の水面までの高さを合計した長さより十分に長く（貯水池の水深によっても相違するが数百ｍ程度）形成されており、このため、所定長さのものを順次接続して必要長さに形成する。
【００４２】
排砂管７は、台船１５上に支持し、その台船１５から排出口１２が、ダム堤体１４の上部を跨いで、貯水池２の水位１７より下部に位置するように敷設する。排砂管７には、適宜バルブ（図示せず）を接続しておく。
【００４３】
なお、水位１７からダム堤体１４の上部までの高さｈが、１０ｍ以上の場合には、後述するサイホン方式による排砂ができないため、例えば台船１５や堤体１４上に配置したポンプ（図示せず）に排砂管７を接続して、そのポンプにより土砂及び水を吸引・圧送するようにする。
【００４４】
台船１５には、排砂管７を支持すると共に、その排砂管７を下方に送り出す送出し装置が設けられていると好都合である。
【００４５】
なお、上記実施の形態では排砂管７が１本の例を挙げて説明したが、複数本の排砂管７をシート状部材５に接続して排砂するようにしてもよい。
【００４６】
次に、本実施の形態の作用を説明する。
【００４７】
上述のように、排砂すべき堆積土砂３の表面４に、シート状部材５を敷設し、排砂管７を接続し、その排砂管７を台船１５を通してダム堤体１４を跨ぐように敷設し、その排出口１２を貯水池２の水位１７より下方に位置させた状態にする。
【００４８】
この際、貯水池２内に沈んだ排砂管７内には貯水が水面近くまで流入している状態にあり、この状態で、排出口１２にポンプ（図示せず）を接続して吸引することで、貯水は台船１５からダム堤体１４を跨いだ排砂管７に流入して流れる。このように排砂管７に一旦貯水が流入した後は、ポンプを外しても、排砂管７はサイホン現象によって常時貯水が排水されることとなる。
【００４９】
このようにサイホン現象による排水が行われた後は、排砂管７の吸引口１１から、常時、貯水が吸引され、これにより、シート状部材５の裏面の堆積土砂３内では、図２及び図５に示すように吸引口１１（排砂穴６）に向かう水流が生じる。この水流は、シート状部材５が不透水性材料で形成されるため、水流は、シート状部材５の裏面で、堆積土砂３の表面４及び内部を通って流れ、この水流に乗って土砂が吸引口１１に向かうようになり、排砂管７を通して土砂が排砂される。
【００５０】
また、シート状部材５の表面には、水頭圧がかかっており、シート状部材５の裏面には、排砂管７の吸引による負圧がかかっている。よって、その水頭圧と負圧とで、シート状部材５を下方に押しつける力が作用する。
【００５１】
これにより、吸引口１１で水と共に排砂された土砂に相当する体積の窪み２４が図５に示すように形成される。シート状部材５は、柔軟な材質で形成されており、その窪み２４の形状に応じて変形する。これにより、シート状部材５の下部の堆積土砂３内、特に吸引作用が大きいシート状部材５の裏面部と堆積土砂３間には、図５に矢印で示したような水流が生じ、その水流と共に土砂がその窪み２４に沿って中央に移動しつつ排砂管７に吸引される。
【００５２】
この窪み２４は、シート状部材５で上方から下方へ押さえられ、かつシート状部材５の裏面が負圧にされるため、窪み２４の表面４の土砂は常にその水流で崩されるため、堆積土砂３が持つ安息角より充分小さくなだらかな窪み２４となる。この窪み２４は、排砂する堆積土砂３の粒径にもよるが、吸引口１１を中心に、シート状部材５の略全体に亘って形成される。
【００５３】
またシート状部材５の周縁部８にはウエイト９が設けられているので、その周縁部８が、ウエイト９により押さえられた状態となり、シート状部材５が、貯水池２内の水の流れによって捲れ上がるのを防止できる。
【００５４】
排砂中、図５に示すように、堆積土砂３中に流木や巨礫など径の大きな異物２５があり、排砂によりその異物２５が、シート状部材５の裏面まで達したとき、異物２５は、シート状部材５で下方へと押さえられるため、土砂と違って水流と共に吸引口１１に流れることなく、そのまま窪み２４の沈下と共に降下していくこととなる。従って、異物２５が排砂管７内に入って、排砂管７を詰まらせたり、吸引口１１を塞ぐことがない。
【００５５】
このように、シート状部材５を敷設したことによって、窪み２４がなだらかな傾斜となり、かつシート状部材５によってその表面側の水が直接排砂管７に流れることを防止する。また、シート状部材５の裏面部に形成される水流による土砂の掃流作用を生じさせると共に、シート状部材５で窪み２４を押さえることで、その土砂の掃流作用を促進させることができ、シート状部材５の全周に亘って平均的に堆積土砂３を排砂することができる。
【００５６】
従って、同位置での排砂管７による堆積土砂３の吸引範囲が広くなる。これによって、台船１５、排砂管７及びシート状部材５の移動回数を大幅に減らすことができ、排砂効率が向上する。
【００５８】
また、上述の排砂方法及び排砂装置１によれば、部分毎に排砂を行った後に移動して、別の位置を排砂することによって、貯水池２全体に亘る排砂を行うことができる。
【００５９】
ここで、図３の試験装置を用いて行った排砂試験について説明する。
【００６０】
図３に示す試験装置は、深さ２００ｃｍの水槽２１に、粒径０．３ｍｍの砂（堆積土砂）３を５０ｃｍの厚さに敷き、その上にシート状部材５を敷設して、その中心の排砂穴６部分にφ３２ｍｍの排砂管７を接続して、サイホン方式により砂３及び水を吸引して排砂するものである。排砂管７の吸引口１１にはφ３００ｍｍのフランジ１６が取り付けられている。なお、図中、２２は、水槽２１に給水を行うための給水管で、その先端は、砂３を掘る流れを作らないように水平方向に向いて開口している。ここで給水を行うのは、水槽２１内の水位を略一定に保つためである。図中、２３は、吸引された砂３と水を溜めるための受水槽である。
【００６１】
図４に本試験による排砂状態を示す。
【００６２】
図４中、破線は、シート状部材５を用いずに排砂管７のみで排砂を行った場合の砂３の窪み形状を示す。この窪みは、砂３が水中での安息角で保持された状態となっている。
【００６３】
本実施形態に係る貯水池の排砂方法を採用した排砂試験によれば、排砂に伴って、堆積土砂３には、排砂管７を中心として窪み２４が形成されていくが、この窪み２４の傾斜は、上述の排砂管７のみで吸引した場合と比較して、大幅に小さくなだらかになる。これは、堆積土砂３の表面４にシート状部材５を敷設して、排砂管７を介してその下部の堆積土砂３を水と共に吸引することにより、上述の作用効果が得られ、堆積土砂３が効率的に排砂されていることの証左となっている。
【００６４】
【発明の効果】
以上要するに本発明によれば、排砂ゲートを用いずに排砂が行え、しかも貯水池の全体に亘って排砂できるといった優れた効果を発揮する。
【図面の簡単な説明】
【図１】本発明に係る貯水池の排砂装置の好適な実施の形態を示した全体断面図である。
【図２】本発明に係る貯水池の排砂装置のシート状部材を示した平面図である。
【図３】本発明に係る貯水池の排砂装置を用いて排砂試験を行った試験装置を示した構成図である。
【図４】排砂試験の排砂の状態を示した断面図である。
【図５】本発明に係る貯水池の排砂装置を用いて行った排砂の状態を示した断面図である。
【符号の説明】
１排砂装置
２貯水池
３堆積土砂
４（堆積土砂の）表面
５シート状部材
６排砂穴
７排砂管
８（シート状部材の）周縁部
９ウエイト
１１（排砂管の）吸引口
１２（排砂管の）排出口
１４（ダム）堤体
１５台船
１７（貯水池の）水位
２４窪み[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reservoir sand discharging method and a sand discharging device for discharging sediment sediment in a reservoir such as a dam lake.
[0002]
[Prior art]
In recent years, dams have been buried in earth and sand at a faster rate than expected. Of the medium-scale dams with a total water storage of more than 1 million cubic meters, 44 dams already have more than half of the reservoir filled with sediment. Reported by the Ministry's survey.
[0003]
For this reason, it has become an important issue to discharge sediment sediment from reservoirs such as dam lakes to restore the amount of water stored at the time of dam construction.
[0004]
Therefore, conventionally, various sand discharging methods as described below have been adopted.
[0005]
(A) Dredging method by grab bucket This method is a method of grabbing sedimentary sediment (sediment) with a grab bucket suspended from a carrier and transporting the sediment to another place by sediment transporter or slurry transport. .
[0006]
(B) Dredging method using suction pipe This method lowers the suction pipe to the bottom of the water from a trolley or a special ship, sucks the sediment with the suction pipe, and transports the sediment to another place by sediment transport ship or slurry transport. Is the method.
[0007]
(C) Sand discharge method using sand discharge gate In this method, a sand discharge pipe is installed in advance below the planned sedimentation surface of the dam body, and a sand discharge gate is provided in the sand discharge pipe. If it becomes higher than the planned sedimentation level, it is a method to open the sand removal gate and discharge the sediment with the drainage of the stored water to the downstream through the sand removal pipe.
[0008]
(D) Sediment drainage method This method lowers the water level of the reservoir, creates a flow similar to a river in the reservoir, and uses the scavenging action to pre-install a sand drain pipe on the dam body. This is a method of transporting sediment through the sand removal gate.
[0009]
However, the above sand removal method has the following problems.
[0010]
In the dredging method using the grab bucket of (A), the sand removal efficiency is low because the sand removal is performed while raising and lowering the grab bucket, and the amount of muddy water generated is large because the sediment is grabbed directly by the grab bucket and lifted. There was a problem that it took time and labor to move while moving the ship.
[0011]
Since the dredging method using the suction pipe in (B) can remove sand continuously, it is more efficient than the dredging method using the grab bucket in (A). When foreign matter such as driftwood is included, it is inevitable that the suction pipe sucks the foreign matter, and there is a problem that the foreign matter is clogged in the suction pipe and the operation is interrupted. Moreover, in the direct suction using the suction pipe, the earth and sand can be sucked only within a narrow range, and it becomes a dred while moving the trolley like the grab bucket.
[0012]
In the sand discharging method using the sand discharging gate of (C), the sediment sediment flowing in the sand discharging pipe is limited to the sediment in the vicinity of the sand discharging pipe, and there is a problem that sand cannot be discharged in a wide range of the reservoir. At the same time, there is a problem that foreign matter is clogged in the sand discharge pipe. In addition, once the sand removal gate is opened, there is a possibility that the sediment may bite into the gate, and there is a possibility that it cannot be closed.
[0013]
In the (D) sweeping sand removal method, in order to create a flow similar to a river in a reservoir, it is necessary to flow all of the reservoir, and the original reservoir function of the dam is lost. There was a problem that could not be implemented unless it was a dam with a quick water level recovery.
[0014]
[Patent Document 1]
Japanese Patent Laid-Open No. 8-13453
[Problems to be solved by the invention]
Among the above methods (A) to (D), the present applicant pays attention to the sand discharging method using the sand discharging gate of (C), and can discharge a wider range of sediment, and foreign matter is clogged. A sand removal method was proposed (Japanese Patent Application No. 2002-062157) to prevent it from occurring.
[0016]
In the method of this prior application, the surface of the sediment around the sand pipe is covered with an impervious water-impervious material, and in that state, a sand discharge gate provided on the sand pipe is opened, and running water is supplied to the sand pipe. This allows the earth and sand to flow from the drainage pipe along with the flowing water. In this sand discharge method, water pressure acts directly on the water-impervious member and the sediment sediment below it is held down by water pressure, so the sand flowing into the sand discharge pipe is carried by the water flow toward the sand discharge pipe and has a relatively small particle size. Since it is earth and sand and a foreign substance with a large diameter cannot be moved because it is pressed by the water-impervious member, it has an excellent effect that clogging by the foreign substance can be solved, and the accumulated earth and sand covered by the water-impervious member can be discharged.
[0017]
However, in the above sand removal method, the sand discharge pipe is buried in the sediment at the start of the sand removal, so when the sand removal gate is opened, the sediment sediment layer in contact with the sand discharge pipe collapses due to its internal pressure, A highly concentrated debris stream flows down the sand discharge pipe. Therefore, since there is a very large pressure fluctuation downstream, there is a risk that facilities such as a sand discharge pipe and a sand discharge gate will be damaged. There is also a problem that dams without sand pipes cannot be used.
[0018]
Furthermore, in this sand removal method, since a sand discharge pipe and a sand discharge gate provided in advance on the dam dam body are used, there is no foreign matter bite, but in the unlikely event that earth and sand flows into the sand discharge gate, There is still a risk that the gate will not close, leaving problems in practical implementation.
[0019]
Accordingly, the present invention has been devised to solve the above-mentioned problems, and is an improvement of the invention of the prior application, in which sand discharge can be performed without using a sand discharge gate, and sand discharge over the entire reservoir. An object of the present invention is to provide a reservoir sand removal method and sand removal device.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, the present invention lays a flexible sheet-like member on earth and sand deposited in a reservoir such as a dam lake, and connects a sand discharge pipe to the center of the sheet-like member. A sand discharging method in which the inside of a sheet-like member is sucked together with the formed water flow from the sand discharging pipe and discharged from the dam dam body together with water from the sand discharging pipe, and a flange is provided at the tip of the suction port of the sand discharging pipe. The sheet-like member is formed into a circular shape, a polygonal shape, or an oval shape, and a chain for preventing the sheet-like member from being lifted is attached to the peripheral portion of the sheet-like member in a ring shape. to face the rear surface side and connected to a suction port of the sediment tube, the deposition surface of the sediment, the from the back portion of the laying to the sheet-like member a sheet-like member covering the sediment along which Suction of the above sand drain pipe into the sediment Rutotomoni to face, and the outlet of Haisunakan and pass over the crest of the reservoir is disposed at a position lower than the water level of the reservoir, the suction discharge of the sediment of the bottom of the sheet-like member by siphon effect a sediment method of reservoir which is adapted to sand.
[0021]
According to the above method, the sheet-like member is laid so as to cover the surface of the accumulated earth and sand, and the suction port of the sand removal pipe is exposed to the accumulated earth and sand from the back surface portion of the sheet-like member, so that the suction sand is discharged. As a result, a water flow can be created between the sheet-like member and the sediment, and the sediment can be efficiently sucked from a wide range by the scavenging action. Further, since a sand discharge gate is not required, it can be applied to a dam that does not have a sand discharge gate, and there is no fear that the sand discharge pipe and the sand discharge gate are clogged.
[0022]
And, while laying a flexible sheet-like member in the earth and sand accumulated in a reservoir such as a dam lake, connecting a sand discharge pipe to the center of the sheet-like member, the inside of the sheet-like member from the sand discharge pipe, It is a sand discharging method that sucks together with the formed water flow and sands out of the dam body with water from the sand discharging pipe, forming a flange at the tip of the suction port of the sand discharging pipe, and rounding the sheet-like member, At the periphery of the sheet-like member, a chain for preventing the sheet-like member from being lifted is attached in a ring shape, and the accumulated sediment along the surface of the accumulated earth and sand is formed. A sheet-like member is installed to cover the sedimentary sand on the back side of the sheet-like member, and the suction port of the above-mentioned sand pipe is connected to the sheet-like member. Let the water level be lower than the above reservoir Placed in position, a sediment method of reservoir which is adapted to suck sediment the sediment of the bottom of the sheet-like member by siphon effect.
[0023]
According to this, since the siphon can obtain a water stream without weight, it is economical.
[0024]
Further, the present invention lays a flexible sheet-like member on the earth and sand accumulated in a reservoir such as a dam lake, and connects a sand discharge pipe to the center of the sheet-like member, and forms a sheet from the sand discharge pipe. A sand discharging device that sucks the inside of a member together with the formed water flow and sands out of the dam body along with water from the sand discharging pipe, and forms a flange at the tip of the suction port of the sand discharging pipe, and forms the sheet The member is formed in a circular, polygonal or elliptical shape, and a chain for preventing the sheet-like member from lifting up is attached to the peripheral edge of the sheet-like member in a ring shape, and the sheet-like member faces the back side. A reservoir sand discharger configured to connect the suction port of the sand discharge pipe to suck and remove the sediment on the back surface of the sheet-like member.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
[0028]
As shown in FIG. 1, the reservoir 2 of the dam is formed by damming a river with a dam body (bank body) 14.
[0029]
Here, the sediment 3 deposited at the bottom of the reservoir 2 where dredging is accumulated over many years since the sediment flowing from the upstream is blocked by the dam body 14.
[0030]
The sedimentary earth and sand 3 is composed of sand having various particle diameters, and the sedimentary earth and sand 3 is mixed with driftwood and boulders which are foreign matters.
[0031]
When discharging the sedimentary earth and sand 3, first, a sheet-like member 5 having a sufficient laying area is laid on the surface 4 of the sedimentary earth and sand 3 to be dredged.
[0032]
This sheet-like member 5 is formed of a water-impervious or hardly water-permeable cloth, resin, rubber, or the like, and has the flexibility to follow the surface 4 of the deposited earth and sand 3 and the property of sinking without floating in water. Yes. The sheet-like member 5 may be formed by providing a mesh-like reinforcing material on the cloth, resin, rubber, or the like.
[0033]
The shape of the sheet-like member 5 is circular or polygonal, and the diameter is formed to be about 100 m in consideration of the range in which a water flow described later acts and the range in which the sedimentary sediment 3 is pressed and sealed by the sheet-like member 5. However, a material in the range of several 10 to several tens of meters can be used.
[0034]
Note that the shape of the sheet-like member 5 is not limited to a circular shape or a polygonal shape, and may be any shape that does not greatly differ from the center to each peripheral edge, such as an ellipse.
[0035]
Specifically, the sheet-like member 5 is laid out in such a manner that the sheet-like member 5 is first folded in a state where the sheet-like member 5 is floated on the reservoir 2, and the target position of the bottom of the water is kept in the folded state. Submerge it and spread it at the bottom of the water. The sheet-like member 5 may be spread near the water surface and gradually submerged in that state.
[0036]
A weight 9 is attached to the peripheral edge 8 of the sheet-like member 5 to prevent the sheet-like member 5 from being lifted by a water flow or the like. The weight 9 is composed of a ring-like ring, such as a chain, that is provided along the entire circumference of the peripheral edge 8 of the sheet-like member 5 and is deformed according to the surface shape of the sediment 3 Then, it is preferable to press the peripheral edge 8 of the sheet-like member 5 against the sediment 3 by the weight of the weight 9.
[0037]
In addition, although the thing which made the chain into the ring shape was demonstrated as an example of the weight 9, this invention is not restricted to this, A weight is attached at intervals along the peripheral part 8 of the sheet-like member 5. May be configured.
[0038]
A sand discharge hole 6 is formed in the center of the sheet-like member 5, and a sand discharge pipe 7 is connected to the back surface portion of the sheet-like member 5 through the sand discharge hole 6 of the suction port 11. It is connected so as to face the sedimentary sediment 3 of.
[0039]
The sand discharge pipe 7 is made of a flexible resin pipe, and its diameter is preferably large in consideration of sand discharge efficiency, but is preferably about 300 mm in consideration of workability. In addition, the sand exhaust pipe 7 may use not only a resin pipe but a part steel pipe.
[0040]
The sand pipe 7 may be connected in advance before the sheet-like member 5 is laid or may be connected after the laying. The sheet-like member 5 and the sand discharge pipe 7 are connected by forming a flange 16 (see FIG. 5) at the tip of the sand discharge pipe 7 and attaching the flange 16 to the sand discharge hole 6 of the sheet-like member 5 in advance. A seat (not shown) is formed, and the flange 16 is installed on the upper side of the seat of the sheet-like member 5 and connected by bolts and nuts.
[0041]
The length of the sand discharge pipe 7 is the sum of the depth of the reservoir 2, the distance from the water surface above the dredging position to the dam body 14, and the height from the upper surface of the dam body 14 to the water surface of the reservoir 2. It is formed sufficiently longer than the length (depending on the depth of the reservoir, although it is about several hundred meters). For this reason, a predetermined length is sequentially connected to form the required length.
[0042]
The sand discharge pipe 7 is supported on a base boat 15 and is laid so that the discharge port 12 extends over the upper part of the dam body 14 and is located below the water level 17 of the reservoir 2. A valve (not shown) is appropriately connected to the sand discharge pipe 7.
[0043]
In addition, when the height h from the water level 17 to the upper part of the dam levee body 14 is 10 m or more, sand removal by the siphon method described later cannot be performed, and therefore, for example, a pump ( A sand discharge pipe 7 is connected to the unillustrated), and earth and sand and water are sucked and pumped by the pump.
[0044]
The trolley 15 is conveniently provided with a delivery device that supports the sand discharge pipe 7 and sends the sand discharge pipe 7 downward.
[0045]
In the above-described embodiment, an example in which the sand discharge pipe 7 is provided has been described. However, a plurality of sand discharge pipes 7 may be connected to the sheet-like member 5 for sand removal.
[0046]
Next, the operation of the present embodiment will be described.
[0047]
As described above, the sheet-like member 5 is laid on the surface 4 of the sediment earth 3 to be drained, the sand discharge pipe 7 is connected, and the sand discharge pipe 7 is straddled across the dam body 14 through the carriage 15. The discharge port 12 is placed below the water level 17 of the reservoir 2.
[0048]
At this time, the water is flowing into the sand drain pipe 7 sinking in the reservoir 2 to the vicinity of the water surface, and in this state, a pump (not shown) is connected to the discharge port 12 for suction. Thus, the water storage flows from the carriage 15 into the sand discharge pipe 7 across the dam body 14. Thus, once the stored water has flowed into the sand discharge pipe 7, even if the pump is removed, the sand discharge pipe 7 always drains the stored water due to the siphon phenomenon.
[0049]
After draining due to the siphon phenomenon in this way, the stored water is always sucked from the suction port 11 of the sand discharge pipe 7, and thereby, in the sediment 3 on the back surface of the sheet-like member 5, FIG. As shown in FIG. 5, a water flow toward the suction port 11 (sand removal hole 6) is generated. Since the sheet-like member 5 is formed of a water-impermeable material, the water stream flows on the back surface of the sheet-like member 5 through the surface 4 and the inside of the sedimentary earth and sand, and the earth and sand are riding on this water stream. It goes to the suction port 11, and earth and sand are discharged through the sand discharge pipe 7.
[0050]
Further, water head pressure is applied to the surface of the sheet-like member 5, and negative pressure due to suction of the sand discharge pipe 7 is applied to the back surface of the sheet-like member 5. Therefore, the force which presses the sheet-like member 5 below acts with the water head pressure and the negative pressure.
[0051]
Thereby, a depression 24 having a volume corresponding to the earth and sand discharged together with water at the suction port 11 is formed as shown in FIG. The sheet-like member 5 is made of a flexible material and deforms according to the shape of the recess 24. As a result, a water flow as indicated by arrows in FIG. 5 is generated in the sediment earth 3 below the sheet-like member 5, particularly between the back surface portion of the sheet-like member 5 having a large suction action and the sediment earth 3. At the same time, the earth and sand are sucked into the sand discharge pipe 7 while moving to the center along the depression 24.
[0052]
Since the depression 24 is pressed downward from above by the sheet-like member 5 and the back surface of the sheet-like member 5 is set to a negative pressure, the earth and sand on the surface 4 of the depression 24 is always broken by the water flow. 3 is a gentle depression 24 that is sufficiently smaller than the angle of repose of 3. The depression 24 is formed over substantially the entire sheet-like member 5 with the suction port 11 as the center, although it depends on the particle size of the sediment 3 to be discharged.
[0053]
Since the weight 9 is provided at the peripheral edge 8 of the sheet-like member 5, the peripheral edge 8 is pressed by the weight 9 and the sheet-like member 5 is drowned by the flow of water in the reservoir 2. It can be prevented from going up.
[0054]
During the sand removal, as shown in FIG. 5, there is a foreign substance 25 having a large diameter such as driftwood or boulders in the sediment earth and sand 25, and when the foreign substance 25 reaches the back surface of the sheet-like member 5 due to the sand removal, Since the sheet-like member 5 is pressed downward, unlike the earth and sand, it does not flow into the suction port 11 together with the water flow, and as it is lowered as the depression 24 sinks. Accordingly, the foreign matter 25 does not enter the sand discharge pipe 7 and clog the sand discharge pipe 7 or block the suction port 11.
[0055]
Thus, by laying the sheet-like member 5, the depression 24 has a gentle slope, and the sheet-like member 5 prevents the water on the surface side from flowing directly to the sand discharge pipe 7. Moreover, while producing the scavenging action of the earth and sand by the water flow formed in the back surface part of the sheet-like member 5, the scavenging action of the earth and sand can be promoted by pressing the depression 24 with the sheet-like member 5, The accumulated sediment 3 can be discharged on average over the entire circumference of the sheet-like member 5.
[0056]
Therefore, the suction range of the sediment earth and sand 3 by the sand discharge pipe 7 in the same position becomes wide. Thereby, the frequency | count of a movement of the trolley 15, the sand discharge pipe 7, and the sheet-like member 5 can be reduced significantly, and sand removal efficiency improves.
[0058]
Moreover, according to the above-mentioned sand discharging method and the sand discharging apparatus 1, the sand can be discharged over the entire reservoir 2 by moving after discharging the sand for each part and discharging sand at another position. it can.
[0059]
Here, the sand removal test performed using the test apparatus of FIG. 3 will be described.
[0060]
The test apparatus shown in FIG. 3 has a water tank 21 having a depth of 200 cm, a sand (deposited earth and sand) 3 having a particle diameter of 0.3 mm is laid on a thickness of 50 cm, and a sheet-like member 5 is laid on the sand. A sand discharge pipe 7 having a diameter of 32 mm is connected to the sand discharge hole 6 and the sand 3 and water are sucked and discharged by a siphon method. A flange 16 having a diameter of 300 mm is attached to the suction port 11 of the sand discharge pipe 7. In the figure, reference numeral 22 denotes a water supply pipe for supplying water to the water tank 21, and its tip is open in the horizontal direction so as not to create a flow for digging the sand 3. The reason for supplying water here is to keep the water level in the water tank 21 substantially constant. In the figure, reference numeral 23 denotes a water receiving tank for storing the sucked sand 3 and water.
[0061]
FIG. 4 shows the state of sand removal by this test.
[0062]
In FIG. 4, a broken line indicates a hollow shape of the sand 3 when sand removal is performed only with the sand discharge pipe 7 without using the sheet-like member 5. The depression is in a state where the sand 3 is held at a repose angle in water.
[0063]
According to the sand removal test employing the reservoir sand removal method according to the present embodiment, a depression 24 is formed in the sedimentary earth 3 around the sand removal pipe 7 along with the sand removal. Compared with the case where it suck | sucks only with the above-mentioned sand removal pipe | tube 7, the inclination of 24 becomes much smaller and gentle. This is because the sheet-like member 5 is laid on the surface 4 of the sedimentary earth and sand, and the sedimentary earth and sand 3 in the lower part thereof is sucked together with water through the sand removal pipe 7, whereby the above-mentioned effects are obtained. No. 3 is proof that sand is being discharged efficiently.
[0064]
【The invention's effect】
In short, according to the present invention, it is possible to perform sand removal without using a sand discharge gate, and to exhibit the excellent effect that sand can be discharged over the entire reservoir.
[Brief description of the drawings]
FIG. 1 is an overall cross-sectional view showing a preferred embodiment of a sand discharger for a reservoir according to the present invention.
FIG. 2 is a plan view showing a sheet-like member of the reservoir sand discharger according to the present invention.
FIG. 3 is a configuration diagram illustrating a test apparatus that has performed a sand discharge test using the reservoir sand discharge apparatus according to the present invention.
FIG. 4 is a cross-sectional view showing a state of sand removal in a sand removal test.
FIG. 5 is a cross-sectional view showing the state of sand removal performed using the reservoir sand discharge device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sand removal apparatus 2 Reservoir 3 Accumulated sediment 4 (Sediment sediment) Surface 5 Sheet-like member 6 Sand removal hole 7 Sand removal pipe 8 Perimeter part (of sheet-like member) Weight 11 (Sand discharge pipe) Suction port 12 ( Drain outlet 14 (dam) dam body 15 trolley 17 water level 24 (reservoir) dimple

Claims

A flexible sheet-like member is laid on the sediment deposited in a reservoir such as a dam lake, and a sand discharge pipe is connected to the center of the sheet-like member, and the inside of the sheet-like member is formed from the sand discharge pipe. Is a sand discharge method for sucking together with the water flow and discharging sand from the sand discharge pipe together with water to the outside of the dam dam body, forming a flange at the tip of the suction port of the sand discharge pipe, and forming the sheet-like member into a circular, polygonal shape Alternatively, it is formed in an elliptical shape, and a chain for preventing the sheet-like member from being lifted is attached to the periphery of the sheet-like member in a ring shape. Connect a mouth, lay a sheet-like member covering the accumulated sediment along the surface of the accumulated sediment, and expose the suction port of the sand discharge pipe to the accumulated sediment from the back surface of the sheet-like member. Mase Rutotomoni, the outlet of the Haisunakan And pass over the crest of the reservoir is disposed at a position lower than the water level of the reservoir, sediment of reservoirs, characterized in that so as to suction Haisuna the sediment of the bottom of the sheet-like member by siphon effect Method.

A flexible sheet-like member is laid on the sediment deposited in a reservoir such as a dam lake, and a sand discharge pipe is connected to the center of the sheet-like member, and the inside of the sheet-like member is formed from the sand discharge pipe. Is a sand discharge method for sucking together with the water flow and discharging sand from the sand discharge pipe together with water to the outside of the dam dam body, forming a flange at the tip of the suction port of the sand discharge pipe, and forming the sheet-like member into a circular, polygonal shape Alternatively, it is formed in an elliptical shape, and a chain for preventing the sheet-like member from being lifted is attached to the periphery of the sheet-like member in a ring shape, and the accumulated earth and sand are covered along the surface of the accumulated earth and sand. A sheet-like member is laid, and the suction port of the above-mentioned sand drain pipe is connected to the sheet-like member facing the sediment on the back side, and the discharge port of the sand pipe is passed over the reservoir body. In a position lower than the water level of the above reservoir Location, and sediment method of reservoirs, characterized in that so as to suction sediment the sediment of the bottom of the sheet-like member by siphon effect.

A flexible sheet-like member is laid on the sediment deposited in a reservoir such as a dam lake, and a sand discharge pipe is connected to the center of the sheet-like member, and the inside of the sheet-like member is formed from the sand discharge pipe. A sand discharging device that sucks together with the water flow and discharges the sand together with the water from the dam dam body, forming a flange at the tip of the suction port of the sand discharging tube, and forming the sheet-like member into a circular, polygonal shape Alternatively, it is formed in an elliptical shape, and a chain for preventing the sheet-like member from being lifted is attached to the periphery of the sheet-like member in a ring shape. A drainage device for a reservoir, characterized in that the mouth is connected to suck and remove the sediment on the back surface of the sheet-like member.