JP4082269B2

JP4082269B2 - Reservoir sand discharging method and sand discharging device

Info

Publication number: JP4082269B2
Application number: JP2003123926A
Authority: JP
Inventors: 敬一西村
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 2003-04-28
Filing date: 2003-04-28
Publication date: 2008-04-30
Anticipated expiration: 2023-04-28
Also published as: JP2004324355A

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砂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砂して、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、吸引管による浚渫や排砂ゲートによる浚渫等、種々の排砂方法（例えば、特許文献１参照）が採用されていた。
【０００５】
しかしながら、上述の従来の排砂方法は、一度に広い範囲の堆積土砂を排砂できない、排砂管に異物の詰まりが生じる等の問題があった。
【０００６】
そこで、本出願人は、広い範囲の堆積土砂を排砂できると共に、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。
【０００７】
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。
【０００８】
しかし、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。さらに、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。
【０００９】
そこで、本出願人は、上記排砂方法をさらに改良して、排砂ゲートを用いずに排砂が行える貯水池の排砂方法及び排砂装置を提案（特願２００３−６１３８０号）した。
【００１０】
この排砂方法は、図４に示すように、ダム湖等の貯水池２に堆積する土砂３を排砂管７により吸引して排砂する排砂方法において、堆積土砂３の表面４に、これを覆うシート状部材５を敷設し、そのシート状部材５の裏面部より排砂管７の吸引口１１を堆積土砂３の表面４に臨ませて吸引排砂するようにしたことを特徴とする。
【００１１】
これによれば、排砂管７の吸引によって、シート状部材５と堆積土砂３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３を広い範囲から効率的に吸引することができると共に、従来利用されてい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いった優れた効果が奏される。
【００１２】
【特許文献１】
特開平８−１３４５３号公報
【００１３】
【発明が解決しようとする課題】
ところで、ダム等の貯水池に堆積する堆積土砂は、粒径が様々な砂やシルト等にて構成されている。しかしながら、上述の排砂方法及び排砂装置では、効率的に排砂できる土砂の粒径が限られてしまうことが実験により判った。例えば、排砂される堆積土砂３が細砂（粒径約０．３ｍｍ）で構成される場合には、シート状部材５と堆積土砂３との間に程良い水流が発生して、非常に効率的な吸引排砂が行われるが、堆積土砂３が粗砂（粒径約１．０ｍｍ）やシルト（粒径約０．０４ｍｍ）で構成される場合には、効率的な吸引排砂が十分に行われないことが判った。
【００１４】
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、堆積土砂の粒径に拘わらず、効率的に排砂が行え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。
【００１５】
【課題を解決するための手段】
上記目的を達成するために、請求項１の発明は、ダム湖等の貯水池に堆積する堆積土砂に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、上記シート状部材を円形或いは多角形状に形成すると共に、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の堆積土砂に臨ませて上記排砂管の吸引口を接続し、上記堆積土砂を排砂するとき、上記貯水池内に浮かべられた台船より排砂管の吸引口と堆積土砂との間に隙間が形成されるように排砂管を吊り下げ、他方上記堆積土砂の表面に、これに沿って堆積土砂を覆うシート状部材を敷設すると共に、排砂管による吸引で上記シート状部材と堆積土砂との間に水流を発生させて堆積土砂の表面を排砂し、且つ排砂管内の吸い込み圧と土砂濃度とをモニタリングしながら堆積土砂面の低下に応じて上記排砂管を下降させるようにした貯水池の排砂方法である。
【００１６】
請求項２の発明は、上記堆積土砂を排砂するとき、上記排砂管の吸引口近傍に上記シート状部材の表面側より裏面側へと貯水を導入して、上記吸引口近傍の堆積土砂を撹拌して吸引排砂を促進する請求項１記載の貯水池の排砂方法である。
【００１７】
請求項３の発明は、ダム湖等の貯水池に堆積する堆積土砂に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、上記シート状部材を円形或いは多角形状に形成すると共に、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の堆積土砂に臨ませて上記排砂管の吸引口を接続し、上記堆積土砂を排砂するとき、上記貯水池内に浮かべられた台船より排砂管の吸引口と堆積土砂との間に隙間が形成されるように排砂管を吊り下げ、他方上記堆積土砂の表面に、これに沿って堆積土砂を覆うシート状部材を敷設すると共に、このシート状部材の裏面側の堆積土砂を吸引排砂するように構成し、上記排砂管に、その吸い込み圧を計測する圧力計を接続すると共に、排砂管内を流れる土砂水の土砂濃度を計測する土砂濃度計を接続し、上記台船に、上記排砂管の吸引口と堆積土砂との間に隙間が形成されるように排砂管を吊り下げると共に排砂管内の吸い込み圧と土砂濃度とをモニタリングしながら上記吸引排砂に伴う堆積土砂面の低下に応じて上記排砂管を下降させるための降下手段を設けた貯水池の排砂装置である。
【００１８】
請求項４の発明は、上記排砂管の吸引口の近傍に、上記シート状部材の表面側より裏面側へと貯水を導入して、上記吸引口近傍の堆積土砂を撹拌させる土砂撹拌手段を設けた請求項３記載の貯水池の排砂装置である。
【００１９】
請求項５の発明は、上記土砂撹拌手段が、上記排砂管の吸引口近傍に形成され上記シート状部材の表面側より裏面側へと貯水を導入するための導入孔からなり、この導入孔から導入される貯水の水流で上記堆積土砂を撹拌するように構成された請求項４記載の貯水池の排砂装置である。
【００２０】
請求項６の発明は、上記土砂撹拌手段が、上記排砂管の吸引口近傍に設けられた噴射管と、該噴射管に接続された貯水を供給する撹拌用ポンプとからなる請求項４記載の貯水池の排砂装置である。
【００２１】
【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。
【００２２】
図１は、本発明の第一の実施の形態を示した全体断面図である。
【００２３】
図１に示すように、堆積土砂３を排砂するに際しては、まず、貯水池２内に浮かべられた台船１５より、堆積土砂３を吸引排砂するための排砂管７を吊り下げると共に、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。
【００２４】
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。
【００２５】
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。
【００２６】
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、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。
【００２７】
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が貯水池２内の水流等によって浮き上がるの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。
【００２８】
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の表面部から裏面側の堆積土砂３に臨むように接続される。
【００２９】
排砂管７は、可撓性のある樹脂管や、ゴムホースなどの可撓管からなり、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、可撓管だけでなく一部鋼管を使用してもよい。
【００３０】
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の先端の吸引口１１の周囲にフランジ１６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。
【００３１】
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（図４参照）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。
【００３２】
排砂管７は、台船１５上に支持し、その台船１５から排出口（図４参照）１２が、ダム堤体１４の上部を跨いで、ダム堤体１４よりも下流側に位置するように敷設する。排砂管７には、吸引排砂用のポンプ２１と適宜バルブ（図示せず）を接続しておく。
【００３３】
このポンプ２１によって、排砂管７の吸引口１１から、シート状部材５の裏面部の堆積土砂３が水と共に吸引され、ダム堤体１４の下流側の排出口１２から下流側へと排出される。
【００３４】
このとき、シート状部材５の裏面側では、シート状部材５と堆積土砂３の表面４との間に吸引口１１へと向かう水平方向の水流が発生し、その掃流作用によって、堆積土砂３は、その表面４が崩されて吸引口１１まで流され、排砂管７によって吸引排砂される。
【００３５】
以上説明した構成は、先願（特願２００３−６１３８０号）の排砂方法及び排砂装置と同様である。
【００３６】
ところで、この堆積土砂３の排砂は、堆積土砂３を構成する砂やシルトの粒径によって大きく効率が左右されることが実験により判った。先願の構成では、堆積土砂３が細砂（粒径約０．３ｍｍ）である場合に、効率的に排砂できるが、堆積土砂３が粗砂（粒径約１．０ｍｍ）である場合には、図５に示すように、排砂管７が、フランジ１６を底部として堆積土砂３内に沈み込んでしまう傾向がある。
【００３７】
これは、粗砂は砂間の間隙が多いため、透水係数が大きく、排砂管７によって吸引される水の全量が、排砂管７の吸引口１１に設けられたフランジ１６の下部から吸い上げられるので、排砂管７が堆積土砂３内に沈み込むためである。そのため、シート状部材５の裏面側で水平方向の水流が発生せず、掃流作用が起こらないので、効率的な排砂ができない。
【００３８】
そこで、本実施の形態では、堆積土砂３が粗砂からなる場合も排砂管７の沈み込みを防止して掃流作用を起こすために、台船１５に、吸引排砂に伴う堆積土砂３面の低下に応じて排砂管７を下降させる降下手段２６を設けた。
【００３９】
以下、これについて説明する。
【００４０】
台船１５には、降下手段２６となる巻上機２４が設けられており、その巻上機２４に巻かれた牽引ロープ２５の下端を排砂管７の先端のフランジ１６に接続し、排砂管７を吊り下げて支持する。
【００４１】
排砂管７には、その吸い込み圧を計測する圧力計２２と内部を流れる土砂水の土砂濃度を計測する土砂濃度計２３とを接続しておく。
【００４２】
降下手段２６は、巻上機２４によって排砂管７を一定速度で下降させつつ、圧力計２２と土砂濃度計２３とで吸い込み圧と土砂濃度をモニタリングしながら、その検出値に応じて、下降速度を変化させる。具体的には、排砂管７の吸引口１１が堆積土砂３の表面４から離れ過ぎると、土砂の流量が減って土砂濃度が低くなるため、これを検知したときに、フランジ１６の下降速度を速くする。一方、排砂管７の吸引口１１が堆積土砂３の表面４に近づき過ぎると、それに応じて水流量が減り土砂濃度が高くなると共に、吸い込み圧が低下するため、これを検知したときに、フランジ１６の下降を停止するか或いは上昇を行う。
【００４３】
これによって、排砂管７の沈み込みを防止できると共に、排砂管７下部のフランジ１６と堆積土砂３の表面４に適度な隙間を確保することができ、その隙間に、吸引口１１へ向かう水平方向の水流が発生する。よって、この水流により掃流作用が起こり堆積土砂３の表面４から土砂が順次崩され、水流と共に中央に移動した後、排砂管７に吸引される。そして、堆積土砂３の表面４は、その土砂の安息角よりも平らになり、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。
【００４４】
なお、排砂管７の途中に、排砂される堆積土砂３の採取装置（図示せず）を設け、サンプリングした堆積土砂３の粒径を調べて、これに応じて排砂管７の下降速度を変化させるときの土砂濃度及び吸い込み圧を決定するようにしてもよい。この場合、土砂濃度及び吸い込み圧は予め実験等により最適値を求めて設定しておく。
【００４５】
そして、シート状部材５を敷設した部分での排砂が終了した後は、シート状部材５を順次別の位置に移動して排砂を行うことによって、貯水池２全体に亘る排砂を行う。
【００４６】
ところで、堆積土砂３がシルト（粒径約０．０４ｍｍ）で構成される場合には、図６に示すように、シート状部材５が堆積土砂３の表面４に貼り付いてしまい、排砂管７による吸引排砂ができない。
【００４７】
これは、シルトは粒間の間隙が少ないため、透水係数が小さく、排砂管７によって吸引される水が、吸引口１１付近に供給されないため、フランジ１６及びシート状部材５が堆積土砂３に貼り付いて水流が発生せず、掃流作用が起こらないので、吸引排砂ができないためである。
【００４８】
そこで、図２に示す本発明の第二の実施の形態は、堆積土砂３がシルトからなる場合でも、シート状部材５の貼り付きを防止して掃流作用を起こさせるように、フランジ１６に、シート状部材５の表面側より裏面側へと貯水を導入して、吸引口１１近傍の堆積土砂を撹拌させる土砂撹拌手段３４として、導入孔２８を形成した。
【００４９】
導入孔２８は、裏面側端部が表面側端部に対してフランジ１６の中心側に近くなるように傾斜して形成されており、表面側から裏面側へと導入される貯水の水流が吸引口１１の下部の堆積土砂３の表面４に向かって流れるように構成されている。導入孔２８は、排砂管７の内径よりも十分に小さい内径を有しており、フランジ１６に複数（本実施の形態では２箇所）形成されている。なお、導入孔２８は、１箇所或いは３箇所以上であってもよい。
【００５０】
なお、導入孔２８は、フランジ１６に形成する代わりに、シート状部材５に形成してもよい。
【００５１】
上記構成によれば、導入孔２８よりシート状部材５の裏面部へ貯水が吸い込まれる。これは、排砂管７による吸引によって、シート状部材５の裏面部が表面部よりも低い水圧となっているためである。
【００５２】
よって、シート状部材５の表面側から裏面側へと排砂管７に吸引される水を供給することができるので、フランジ１６やシート状部材５が、堆積土砂３の表面４に貼り付くのを防止できると共に、導入孔２８より流入する貯水によって水流が発生する。その掃流作用によって堆積土砂３の表面４が崩され、堆積土砂３が撹拌されるので、土砂が排砂管７に吸引されやすくなる。
【００５３】
この撹拌によって、堆積土砂３の表面４には、窪み３３が一旦竪穴状に形成されるが、この窪み３３の壁面は、水流によって撹拌されると共に、堆積土砂３の内圧（図中矢印にて示す）がかかってくるので、排砂管７の吸引口１１の下部に次々と崩れていき、排砂されていく。よって、土砂の撹拌が窪み３３の水平方向に広がっていき、堆積土砂３を安息角よりも平らにすることができる。
【００５４】
さらに、導入孔２８の内径が排砂管７の内径よりも十分小さく形成されているので、導入孔２８から流れる水流の流速を速くすることができ、撹拌効率を向上できる。
【００５５】
このとき、堆積土砂３が撹拌されて濁水が発生するが、その上部はシート状部材５及びフランジ１６で覆われているので、貯水池２内に濁水が流れ込むことはない。
【００５６】
なお、本実施の形態に、第一の実施の形態の降下手段２６を設ければ、堆積土砂３が粗砂の場合でもシルトの場合でも対応することができるので、排砂中に堆積土砂３が変化しても、連続して効率的な排砂を行うことができる。
【００５７】
図３は、本発明の第三の実施の形態を示した要部断面図である。本実施の形態も上記第二の実施の形態と同様に、堆積土砂３がシルトで構成される場合に適用される排砂方法及び排砂装置を示したものである。
【００５８】
かかる排砂装置の土砂撹拌手段３４は、積極的に堆積土砂３の撹拌を行うために、排砂管７の吸引口１１近傍に設けられた噴射管３５と、この噴射管３５に堆積土砂３を撹拌するための貯水を供給する撹拌用ポンプ３９とからなる。なお、その他の構成については、上記第二の実施の形態と同様である。
【００５９】
噴射管３５は、フランジ１６に形成された貫通孔３６に挿通されるパイプ３７と、そのパイプ３７に接続される高圧水ホース３８とで構成される。本実施の形態では噴射管３５は、吸引口１１の近傍に２本設けられている。なお、噴射管３５の本数は２本に限られるものではない。
【００６０】
パイプ３７は、金属等からなり、貫通孔３６に嵌合されている。パイプ３７の先端は、排砂管７の下部の堆積土砂３の表面４近傍或いは若干堆積土砂３内に差し込まれる位置まで延出しており、堆積土砂３の表面４或いは内部に直接貯水の水流を当てるようになっている。高圧水ホース３８は、ゴムや樹脂等の可撓性を有する材質からなり、排砂管７の下降に追従できるように構成されている。高圧水ホース３８の上流側端は、撹拌用ポンプの吐出口へと接続されている。
【００６１】
本実施の形態によれば、排砂管７の吸引とは別の水流発生源を有しているので、第二の実施の形態の土砂撹拌手段３４よりも強い水流を発生させることができ、撹拌効果が大きい。さらに、パイプ３７の先端が、堆積土砂３の表面４近傍或いは若干堆積土砂３内に差し込まれる位置まで延出しているので、水流を堆積土砂３の表面４のより近くに当てることができ、さらに撹拌効果が大きく、排砂効率を大幅に向上できる。
【００６２】
従って、堆積土砂３がさらに粒径の小さいシルトや粘土等によって構成される場合であっても、堆積土砂３の撹拌が行え、水流による掃流作用を起こすことができるので効率的な排砂が行える。
【００６３】
また、撹拌用ポンプ３９によって、水流の強弱を調整したり、脈動流を発生させたりすることによって、撹拌効果をさらに大きくすることもできる。
【００６４】
【発明の効果】
以上要するに本発明によれば、堆積土砂の粒径に拘わらず、効率的に排砂が行え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第一の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好適な第二の実施の形態を示した要部断面図である。
【図３】本発明に係る貯水池の排砂装置の好適な第三の実施の形態を示した要部断面図である。
【図４】貯水池の排砂装置を示した全体断面図である。
【図５】図４の排砂装置で粗砂からなる堆積土砂を排砂した状態を示した断面図である。
【図６】図４の排砂装置でシルトからなる堆積土砂を排砂した状態を示した断面図である。
【符号の説明】
２貯水池
３堆積土砂
４（堆積土砂の）表面
５シート状部材
７排砂管
１１（排砂管の）吸引口
１５台船
２６降下手段
２８導入孔
３４土砂撹拌手段
３５噴射管
３９撹拌用ポンプ[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a reservoir sand discharging method and a sand discharging device for discharging sand deposited 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 remove the sediment from sediment reservoirs such as dam lakes and restore the amount of water stored during dam construction.
[0004]
Therefore, conventionally, various sand discharging methods (for example, refer to Patent Document 1) such as dredging with a suction pipe and dredging with a sand discharging gate have been adopted.
[0005]
However, the above-described conventional sand removal method has problems such as being unable to remove a wide range of sediment at a time and clogging of foreign matter in the sand discharge pipe.
[0006]
Accordingly, the present applicant has proposed a sand removal method (Japanese Patent Application No. 2002-062157) that can remove a wide range of sediment and prevent clogging of foreign matters.
[0007]
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.
[0008]
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. In addition, because the sand discharge pipe and sand discharge gate provided in advance on the dam body are used, there is no possibility of foreign matter biting, but in the unlikely event that earth and sand flows into the sand discharge gate, the sand discharge gate may not close. There is still a problem with realistic implementation.
[0009]
Accordingly, the present applicant has further improved the above-mentioned sand removal method and proposed a reservoir sand removal method and sand removal apparatus (Japanese Patent Application No. 2003-61380) that can perform sand removal without using a sand removal gate.
[0010]
As shown in FIG. 4, this sand removal method is a sand removal method in which the earth and sand 3 deposited in the reservoir 2 such as a dam lake is sucked by the sand discharge pipe 7 to remove the sand. A sheet-like member 5 is laid, and the suction port 11 of the sand discharge pipe 7 is made to face the surface 4 of the sedimentary earth and sand 3 from the back surface of the sheet-like member 5 to perform suction sand removal. .
[0011]
According to this, a water flow can be created between the sheet-like member 5 and the sediment 3 by suction of the sand removal pipe 7, and the sediment 3 is efficiently suctioned from a wide range by the sweeping action by this. In addition, since a sand removal gate that has been used conventionally is not required, an excellent effect that it can be applied to a dam that does not include a sand removal gate is achieved.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 8-13453
[Problems to be solved by the invention]
By the way, sedimentary sediment deposited in a reservoir such as a dam is composed of sand, silt or the like having various particle sizes. However, it has been experimentally found that the above-mentioned sand discharging method and sand discharging device limit the particle size of earth and sand that can be efficiently discharged. For example, when the sedimentary sediment 3 to be discharged is composed of fine sand (particle size: about 0.3 mm), a moderate water flow is generated between the sheet-like member 5 and the sedimentary sediment 3, Efficient suction sand removal is performed. However, if the sediment 3 is composed of coarse sand (particle size: about 1.0 mm) or silt (particle size: about 0.04 mm), efficient suction sand removal is performed. It turned out that it was not performed enough.
[0014]
Accordingly, the present invention has been devised to solve the above problems, and it provides a reservoir sand discharging method and sand discharging device capable of efficiently discharging sand regardless of the particle size of the sediment. With the goal.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that a 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. A sand discharging method in which the inside of a sheet-like member is sucked together with the formed water flow from the sand pipe and sanded out of the dam dam body with water from the sand discharging pipe , and the sheet-like member is formed into a circular shape or a polygonal shape. A chain for preventing the sheet-like member from being lifted is attached to the peripheral edge of the sheet-like member in a ring shape, and the suction port of the sand discharge pipe is connected to the sheet-like member so as to face the sediment on the back side. When the sedimentary sand is drained, the sandpipe is suspended so that a gap is formed between the suction port of the sandpipe and the sedimentary sediment from the pontoon floated in the reservoir, while the sediment Sediment along the surface of the earth and sand With laying sheet-like member for covering the to Haisuna the surface of the sediment by generating water flow between the sheet-like member and the sediment with suction by sediment tube, and suction pressure and sediment sediment tube This is a reservoir sand discharging method in which the sand discharging pipe is lowered in accordance with a decrease in the sediment level while monitoring the concentration .
[0016]
According to the second aspect of the present invention, when the sedimentary sediment is discharged , water is introduced from the front surface side to the back surface side of the sheet-like member in the vicinity of the suction port of the sand discharge pipe, and the sedimentary sediment in the vicinity of the suction port is introduced. The method for discharging sand in a reservoir according to claim 1, wherein the suction sand removal is promoted by stirring the water.
[0017]
In the invention of claim 3 , a 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. , a Haisuna apparatus for discharging sand dam outside than with the water sediment tube by suction with water to be formed, thereby forming the sheet-like member in a circular or polygonal shape, the peripheral portion of the sheet-like member A chain for preventing the sheet-like member from being lifted up is attached in a ring shape, and the suction port of the sand discharge pipe is connected to the sheet-like member so as to face the sediment on the back side thereof, and the sediment is removed. When the sand pipe is hung from the trolley floated in the reservoir so that a gap is formed between the suction port of the sand sand pipe and the sediment, and the surface of the sediment is Laying a sheet-like member covering the sediment Rutotomoni, of the sheet-like member to the back surface side of the sediment configured to suction sediment in the sediment tube, with connecting a pressure gauge for measuring the suction pressure, the sediment water flowing through the sediment tube Connect a sediment concentration meter to measure the sediment concentration, and suspend the sand discharge pipe to the trolley so that a gap is formed between the suction port of the sand discharge pipe and the accumulated sediment and suck in the sand discharge pipe. A reservoir sand discharger provided with a descent means for lowering the sand discharge pipe in response to a decrease in the sediment sediment level accompanying the suction sand discharge while monitoring pressure and sediment concentration .
[0018]
The invention according to claim 4, in the vicinity of the suction opening of the upper Sharing, ABS sand tube, and introducing water into the back side from the surface side of the sheet-like member, sediment stirring means for stirring the sediment of the suction opening neighborhood The reservoir sand discharging apparatus according to claim 3, wherein
[0019]
According to a fifth aspect of the present invention, the earth and sand agitating means comprises an introduction hole that is formed in the vicinity of the suction port of the sand discharge pipe and introduces water storage from the front surface side to the back surface side of the sheet-like member. The reservoir sand removal device according to claim 4, wherein the sedimentary sediment is agitated by a water flow of the reservoir introduced from the reservoir.
[0020]
According to a sixth aspect of the present invention, the earth and sand agitating means comprises an injection pipe provided in the vicinity of the suction port of the sand discharge pipe, and an agitation pump for supplying stored water connected to the injection pipe. It is a sand removal device of the reservoir.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
[0022]
FIG. 1 is an overall cross-sectional view showing a first embodiment of the present invention.
[0023]
As shown in FIG. 1, when discharging the sediment earth and sand 3, first, the sand discharge pipe 7 for sucking and discharging the sediment earth and sand 3 is suspended from the boat 15 floated in the reservoir 2, A sheet-like member 5 having a sufficient laying area is laid on the surface 4 of the sediment 3 to be dredged.
[0024]
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.
[0025]
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.
[0026]
Specifically, the sheet-like member 5 is laid down by first placing the sheet-like member 5 in a folded state on the trolley 15 and sinking it to the target position of the water bottom in the folded state. Spread and lay in. The sheet-like member 5 may be spread near the water surface and gradually submerged in that state.
[0027]
A weight 9 is attached to the peripheral edge 8 of the sheet-like member 5 to prevent the sheet-like member 5 from floating due to the water flow in the reservoir 2 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.
[0028]
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 side of the sheet-like member 5 through the suction port 11 through the sand discharge hole 6 of the sheet-like member 5. It is connected so as to face the sedimentary sediment 3 of.
[0029]
The sand discharge tube 7 is made of a flexible resin tube or a flexible tube such as a rubber hose, and its diameter is preferably large in consideration of sand discharge efficiency, but about 300 mm in consideration of workability. Are preferred. The sand discharge pipe 7 may be a partially steel pipe as well as a flexible pipe.
[0030]
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 around the suction port 11 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 receiving seat (not shown) is formed, and the flange 16 is installed on the upper side of the receiving seat of the sheet-like member 5 and connected by bolts and nuts.
[0031]
The length of the sand discharge pipe 7 is the depth of the reservoir 2, the distance from the water surface above the dredging position to the dam dam body (see FIG. 4) 14, and the upper surface of the dam dam body 14 to the water surface of the reservoir 2. The length is sufficiently longer than the total length (about several hundreds of meters depending on the depth of the reservoir). For this reason, a predetermined length is sequentially connected to form the required length.
[0032]
The sand discharge pipe 7 is supported on a base boat 15, and a discharge port (see FIG. 4) 12 extends from the base boat 15 to the downstream side of the dam dam body 14 across the upper part of the dam dam body 14. Lay like so. The sand discharge pipe 7 is connected with a suction sand discharge pump 21 and an appropriate valve (not shown).
[0033]
The pump 21 sucks the sediment 3 on the back surface of the sheet-like member 5 together with water from the suction port 11 of the sand discharge pipe 7 and discharges it from the discharge port 12 on the downstream side of the dam body 14 to the downstream side. The
[0034]
At this time, on the back surface side of the sheet-like member 5, a horizontal water flow toward the suction port 11 is generated between the sheet-like member 5 and the surface 4 of the accumulated earth and sand 3, and the sedimentary earth and sand 3 is caused by the sweeping action. The surface 4 is broken and flows to the suction port 11, and is sucked and discharged by the sand discharge pipe 7.
[0035]
The configuration described above is the same as the sand discharging method and sand discharging device of the prior application (Japanese Patent Application No. 2003-61380).
[0036]
By the way, it has been experimentally found that the efficiency of the sand discharge of the sediment earth and sand 3 is greatly influenced by the particle size of sand and silt constituting the sediment earth and sand 3. In the configuration of the prior application, when the sedimentary earth and sand 3 is fine sand (particle size of about 0.3 mm), sand can be discharged efficiently, but when the sedimentary earth and sand 3 is coarse sand (particle size of about 1.0 mm) As shown in FIG. 5, the sand discharge pipe 7 tends to sink into the sediment earth and sand 3 with the flange 16 as the bottom.
[0037]
This is because coarse sand has many gaps between sand, so the water permeability coefficient is large, and the total amount of water sucked by the sand discharge pipe 7 is sucked up from the lower part of the flange 16 provided in the suction port 11 of the sand discharge pipe 7. This is because the sand discharge pipe 7 sinks into the sedimentary earth and sand 3. Therefore, a horizontal water flow does not occur on the back side of the sheet-like member 5, and no scavenging action occurs, so efficient sand removal cannot be performed.
[0038]
Therefore, in the present embodiment, even when the sedimentary sediment 3 is made of coarse sand, the sedimentary sediment 3 associated with the suction sedimentation is sent to the carriage 15 in order to prevent the sedimentation pipe 7 from sinking and cause a scavenging action. A lowering means 26 for lowering the sand discharge pipe 7 in accordance with the lowering of the surface is provided.
[0039]
This will be described below.
[0040]
The trolley 15 is provided with a hoisting machine 24 serving as a lowering means 26, and the lower end of the traction rope 25 wound around the hoisting machine 24 is connected to the flange 16 at the tip of the sand discharge pipe 7, The sand pipe 7 is suspended and supported.
[0041]
A pressure gauge 22 for measuring the suction pressure and a sediment concentration meter 23 for measuring the sediment concentration of sediment water flowing inside are connected to the sand discharge pipe 7.
[0042]
The descent means 26 descends according to the detected value while lowering the sand discharge pipe 7 at a constant speed by the hoisting machine 24 and monitoring the suction pressure and the sediment concentration with the pressure gauge 22 and the sediment concentration meter 23. Change the speed. Specifically, if the suction port 11 of the sand discharge pipe 7 is too far away from the surface 4 of the sedimentary sediment 3, the flow rate of sediment decreases and the sediment concentration becomes low. To speed up. On the other hand, if the suction port 11 of the sand discharge pipe 7 gets too close to the surface 4 of the sedimentary sediment 3, the water flow rate decreases accordingly, the sediment concentration increases, and the suction pressure decreases. The lowering of the flange 16 is stopped or raised.
[0043]
As a result, sinking of the sand discharge pipe 7 can be prevented, and an appropriate gap can be secured between the flange 16 at the lower part of the sand discharge pipe 7 and the surface 4 of the deposited earth and sand 3, and the suction port 11 is directed to the clearance. Horizontal water flow is generated. Accordingly, a sweeping action is caused by this water flow, and the earth and sand are sequentially broken down from the surface 4 of the sedimentary earth and sand 3 and moved to the center together with the water flow and then sucked into the sand discharge pipe 7. And the surface 4 of the sediment earth and sand 3 becomes flat rather than the angle of repose of the earth and sand, and the sediment earth and sand 3 can be discharged on average over the entire periphery of the sheet-like member 5.
[0044]
In addition, a sampling device (not shown) for collecting sediment earth and sand 3 to be drained is provided in the middle of the sand sand pipe 7, and the particle diameter of the sampled sediment earth and sand 3 is examined, and the sand sand pipe 7 descends accordingly. You may make it determine the sediment concentration and suction pressure when changing a speed | rate. In this case, the earth and sand concentration and the suction pressure are set by obtaining optimum values in advance through experiments or the like.
[0045]
And after the sand removal in the part which laid the sheet-like member 5 is complete | finished, the sheet-like member 5 is moved to another position one by one, and sand discharge over the reservoir 2 whole is performed.
[0046]
By the way, when the sediment 3 is made of silt (particle size: about 0.04 mm), as shown in FIG. 6, the sheet-like member 5 sticks to the surface 4 of the sediment 3 and the sand discharge pipe No suction sand removal by 7.
[0047]
This is because silt has a small intergranular gap and has a small water permeability coefficient, so that water sucked by the sand discharge pipe 7 is not supplied to the vicinity of the suction port 11, so that the flange 16 and the sheet-like member 5 are attached to the sediment 3. This is because water flow does not occur due to sticking and no scavenging action occurs, so suction sand removal cannot be performed.
[0048]
Therefore, in the second embodiment of the present invention shown in FIG. 2, even when the sediment 3 is made of silt, the flange 16 is made to prevent the sheet-like member 5 from sticking and cause a scavenging action. In addition, water was introduced from the front surface side to the back surface side of the sheet-like member 5, and the introduction hole 28 was formed as the earth and sand agitating means 34 for agitating the accumulated earth and sand in the vicinity of the suction port 11.
[0049]
The introduction hole 28 is formed to be inclined so that the end on the back surface side is closer to the center side of the flange 16 with respect to the end on the surface side, and the water flow of the water introduced from the surface side to the back surface side is sucked in. It is configured to flow toward the surface 4 of the sediment earth and sand 3 below the mouth 11. The introduction hole 28 has an inner diameter sufficiently smaller than the inner diameter of the sand discharge pipe 7, and a plurality of (two in the present embodiment) are formed in the flange 16. The introduction hole 28 may be one place or three places or more.
[0050]
The introduction hole 28 may be formed in the sheet-like member 5 instead of being formed in the flange 16.
[0051]
According to the above configuration, the stored water is sucked into the back surface portion of the sheet-like member 5 from the introduction hole 28. This is because the back surface portion of the sheet-like member 5 has a lower water pressure than the front surface portion due to suction by the sand discharge pipe 7.
[0052]
Therefore, since the water sucked into the sand discharge pipe 7 can be supplied from the front surface side to the back surface side of the sheet-like member 5, the flange 16 and the sheet-like member 5 stick to the surface 4 of the sedimentary earth and sand 3. And a water flow is generated by the stored water flowing in from the introduction hole 28. The surface action 4 of the sedimentary sediment 3 is destroyed by the sweeping action and the sedimentary sediment 3 is agitated, so that the sediment is easily sucked into the sand discharge pipe 7.
[0053]
By this stirring, a depression 33 is once formed in the surface 4 of the sedimentation earth 3 in the shape of a pit. The wall surface of this depression 33 is agitated by a water flow and the internal pressure of the sedimentation earth 3 (as indicated by an arrow in the figure). As shown in the figure, the bottom of the suction port 11 of the sand discharge pipe 7 collapses one after another, and the sand is discharged. Therefore, stirring of earth and sand spreads in the horizontal direction of the depression 33, and the sediment earth and sand 3 can be made flatter than the repose angle.
[0054]
Furthermore, since the inner diameter of the introduction hole 28 is formed sufficiently smaller than the inner diameter of the sand discharge pipe 7, the flow velocity of the water flow flowing from the introduction hole 28 can be increased, and the stirring efficiency can be improved.
[0055]
At this time, although the sediment 3 is agitated and turbid water is generated, the turbid water does not flow into the reservoir 2 because the upper portion is covered with the sheet-like member 5 and the flange 16.
[0056]
If the descent means 26 of the first embodiment is provided in the present embodiment, it is possible to cope with the case where the accumulated earth and sand 3 is coarse sand or silt, so that the accumulated earth and sand 3 is discharged during the sand discharge. Even if changes, efficient sand removal can be performed continuously.
[0057]
FIG. 3 is a cross-sectional view of a main part showing a third embodiment of the present invention. Similarly to the second embodiment, this embodiment also shows a sand discharging method and a sand discharging device applied when the sediment earth and sand 3 is made of silt.
[0058]
In order to positively agitate the accumulated sediment 3, the sediment agitation means 34 of the sand removal apparatus has an injection pipe 35 provided in the vicinity of the suction port 11 of the sand discharge pipe 7, and the accumulated sediment 3 in the injection pipe 35. And an agitation pump 39 for supplying water for agitation. Other configurations are the same as those in the second embodiment.
[0059]
The injection pipe 35 includes a pipe 37 inserted through a through hole 36 formed in the flange 16 and a high-pressure water hose 38 connected to the pipe 37. In the present embodiment, two injection pipes 35 are provided in the vicinity of the suction port 11. Note that the number of the injection pipes 35 is not limited to two.
[0060]
The pipe 37 is made of metal or the like and is fitted in the through hole 36. The tip of the pipe 37 extends to the position near the surface 4 of the sedimentary sediment 3 below the sand removal pipe 7 or to a position where it is slightly inserted into the sedimentary sediment 3. It comes to guess. The high-pressure water hose 38 is made of a flexible material such as rubber or resin, and is configured to follow the descending of the sand discharge pipe 7. The upstream end of the high-pressure water hose 38 is connected to the discharge port of the stirring pump.
[0061]
According to the present embodiment, since it has a water flow generation source different from the suction of the sand discharge pipe 7, it is possible to generate a stronger water flow than the earth and sand agitating means 34 of the second embodiment, Great stirring effect. Furthermore, since the tip of the pipe 37 extends to the vicinity of the surface 4 of the sedimentary sediment 3 or a position where it is slightly inserted into the sedimentary sediment 3, the water flow can be applied closer to the surface 4 of the sedimentary sediment 3. The agitation effect is large, and sand discharge efficiency can be greatly improved.
[0062]
Therefore, even if the sediment 3 is made of silt or clay having a smaller particle size, the sediment 3 can be agitated and a scavenging action can be caused by the water flow, so that efficient sand removal is possible. Yes.
[0063]
Further, the stirring effect can be further increased by adjusting the strength of the water flow or generating a pulsating flow with the stirring pump 39.
[0064]
【The invention's effect】
In short, according to the present invention, an excellent effect is achieved that sand can be discharged efficiently regardless of the particle size of the sediment.
[Brief description of the drawings]
FIG. 1 is an overall cross-sectional view showing a first preferred embodiment of a reservoir sand discharging apparatus according to the present invention.
FIG. 2 is a cross-sectional view of a principal part showing a second preferred embodiment of the reservoir sand discharger according to the present invention.
FIG. 3 is a cross-sectional view of a principal part showing a third preferred embodiment of the reservoir sand discharger according to the present invention.
FIG. 4 is an overall cross-sectional view showing a reservoir sand removal device.
5 is a cross-sectional view showing a state in which sedimentary earth and sand made of coarse sand has been discharged by the sand discharger of FIG. 4. FIG.
6 is a cross-sectional view showing a state in which sedimentary earth and sand made of silt has been removed by the sand removal apparatus of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 Reservoir 3 Accumulated sediment 4 (Sediment sediment) surface 5 Sheet-shaped member 7 Sand discharge pipe 11 (Sand discharge pipe) Suction port 15 Base ship 26 Descent means 28 Introduction hole 34 Sediment agitation means 35 Injection pipe 39 Stirring pump

Claims

A 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 sucked together with the formed water flow from the sand discharge pipe. A sand discharging method for discharging sand from the dam body together with water from the sand discharging pipe, and forming the sheet-like member in a circular or polygonal shape and preventing the sheet-like member from being lifted at the peripheral edge of the sheet-like member A chain is attached in a ring shape, and the suction port of the sand drain pipe is connected to the sheet-like member on the backside of the sediment, and when the sediment is drained , it floats in the reservoir. The sand discharge pipe is suspended so that a gap is formed between the suction port of the sand discharge pipe and the accumulated sediment from the pontoon, and on the other hand, the surface of the accumulated sediment is covered with the sheet. with laying member, Haisunakan According to generate water flow between the sediment and the sheet-like member at suction Haisuna the surface of the sediment and, and with a decrease of the suction pressure and sediment concentration and sediment surface while monitoring the sediment tube A method of draining a reservoir, wherein the sand drain pipe is lowered.

When discharging the sediment, the water is introduced from the front side of the sheet-like member to the back side in the vicinity of the suction port of the sand discharge pipe, and the sediment in the vicinity of the suction port is agitated to suck the sand. The method for discharging sand in a reservoir according to claim 1, wherein

A 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 sucked together with the formed water flow from the sand discharge pipe. a Haisuna apparatus for discharging sand dam outside together with water from the sediment tube and, together forming the sheet-like member in a circular or polygonal shape, preventing floating of the sheet-like member on the periphery of the sheet-like member A chain is attached in a ring shape, and the suction port of the sand drain pipe is connected to the sheet-like member on the backside of the sediment, and when the sediment is drained , it floats in the reservoir. The sand discharge pipe is suspended so that a gap is formed between the suction port of the sand discharge pipe and the accumulated sediment from the pontoon, and on the other hand, the surface of the accumulated sediment is covered with the sheet. with laying member, the sheet The back side of the sediment of bets like member configured to suction sediment in the sediment tube, with connecting a pressure gauge for measuring the suction pressure, measuring the sediment concentration of sediment water flowing through the sediment tube Connect the earth and sand concentration meter, and suspend the sand pipe so that a gap is formed between the suction port of the sand discharge pipe and the sediment earth and sand, and the suction pressure and sediment concentration in the sand pipe sediment system reservoir, characterized in that the provided drop means for lowering the sediment tube with a decrease in sediment surface associated with the suction sediment while monitoring and.

In the vicinity of the suction opening of the upper Sharing, ABS sand tube, and introducing water into the back side from the surface side of the sheet-like member, according to claim 3 in which a sediment stirring means for stirring the sediment of the suction opening neighborhood sediment apparatus of the reservoir.

The earth and sand agitating means is formed in the vicinity of the suction port of the sand discharge pipe and includes an introduction hole for introducing water storage from the front surface side to the back surface side of the sheet-like member. 5. The reservoir sand removal apparatus according to claim 4, wherein the sedimentation sand is stirred.

The reservoir sand discharge device according to claim 4, wherein the earth and sand agitation means comprises an injection pipe provided in the vicinity of the suction port of the sand discharge pipe, and an agitation pump for supplying water stored in the injection pipe. .