JP2004181393A - Water-barrier structure and water-barrier construction for maritime disposal station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-barrier structure for a maritime disposal station in which a shearing force loaded on a water-barrier sheet due to covering with soil or the like to reduce deformation of the water-barrier sheet for safety and high constructiveness. <P>SOLUTION: In the water-barrier structure for the maritime disposal station, on an at least normal surface portion of the base having a normal surface of the maritime disposal station, multilayer sheets each having the water-barrier sheet and protectors are vertically double laid via an intermediate protecting layer and an upper coating layer is provided on the upper multilayer sheet. The multilayer has three or more layers formed from the water-barrier sheet and protectors provided on upper and lower surfaces of the water-barrier sheet. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

表２ 材料（間）のせん断強度特性
【表２】

【００６２】
図１１は、ＰＶＣシート、長繊維不織布について試験片寸法２０ｃｍ×２０ｃｍにより、通常の引張試験と拘束引張試験を実施した結果である。ここで、拘束引張試験には二軸引張り試験機を用いた。土中に敷設された場合、ネッキングが拘束されると考え、拘束引張試験で得られた弾性係数を用いた。
中間保護層・上部被覆層は海中施工が中心となり、締固めを行わない場合、相対密度がＤｒ＝５０〜６０％程度の緩く堆積した状態になると想定される。スラグの強度変形特性は、初期相対密度Ｄｒ＝６０％の大型供試体（寸法Ｄ３００ｍｍ×Ｈ６００ｍｍ）を用いた圧密排水三軸圧縮試験から求めた。なお、単位体積重量は、気中γ＝２１ｋＮ／ｍ^３、水中γ’＝１４ｋＮ／ｍ^３とした（（財）沿岸開発技術研究センター・鐵鋼スラグ協会：「港湾工事用製鋼スラグ利用手引書」、平成１２年３月）。
【００６３】
（３）安定解析
極限平衡法による安定解析から、検討断面（図１０）における遮水工に必要な層間摩擦角を算定した。極限平衡法であるため、土塊や遮水材に発生する変形・ひずみを無視し、最大摩擦角が滑り面に沿って同時に発揮されると仮定している。
【００６４】
安定解析モデルとして、既往の法面部分を対象とする法面モデル（Ｒ．Ｍ． Ｋｏｅｒｎｅｒ： Ｄｅｓｉｇｎｉｎｇ ｗｉｔｈ Ｇｅｏｓｙｎｔｈｅｔｉｃｓ − ｆｏｕｒｔｈ ｅｄｉｔｉｏｎ， Ｐｒｅｎｔｉｃｅ Ｈａｌｌ， Ｃｈａｐｔｅｒ ５ Ｄｅｓｉｇｎｉｎｇ ｗｉｔｈ Ｇｅｏｍｅｎｂｒａｎｅ， １９９９，Ｊ．Ｐ．Ｇｉｒｏｕｄ ａｎｄ Ｊ．Ｆ．Ｂｅｅｃｈ： Ｓｔａｂｉｌｉｔｙ ｏｆ ｓｏｉｌ ｌａｙｅｒｓ ｏｎ ｇｅｏｓｙｎｔｈｅｔｉｃ ｌｉｎｉｎｇ ｓｙｓｔｅｍ， Ｐｒｏｃｅｅｄｉｎｇｓ ｏｆ Ｇｅｏｓｙｎｔｈｅｔｉｃｓ ’８９， Ｖｏｌ．１， ｐｐ．３５−４６， １９８９）と底面部を含めた全体モデル（図１２）の２種について解析した。
【００６５】
図１２において、以下の式が成り立つ。
Ｎ_Ａ ＝ Ｗ_Ａ ｃｏｓβ − Ｆ
Ｎ_Ｐ ＝ Ｗ_Ｐ ＋ Ｅ_Ｐ ｓｉｎβ − Ｆ’
Ｅ_Ａ ｓｉｎβ ＝ Ｗ_Ａ − Ｎ_Ａ ｃｏｓβ − （ Ｎ_Ａ ｔａｎδ ＋Ｃ_ａ ） ｓｉｎβ ／ Ｆ_Ｓ
Ｅ_Ｐ ｃｏｓβ ＝ （ Ｎ_Ｐ ｔａｎδ ＋ Ｃ ） ／ Ｆ_Ｓ ＋ Ａ_Ｐ
Ｅ_Ａ ＝ Ｅ_Ｐ
【００６６】
ここに、Ｗ_Ａ：滑動土塊総重量（ｋＮ／ｍ）、Ｗ_Ｐ：抵抗土塊総重量（ｋＮ／ｍ）、Ｎ_Ａ：斜面垂直方向の反力（ｋＮ／ｍ）、Ｎ_Ｐ：底面垂直方向の反力（ｋＮ／ｍ）、β：法勾配（°）、Ｆ：法面にかかる波圧（ｋＮ／ｍ）、Ｆ’：底面にかかる波圧（ｋＮ／ｍ）、Ｐ_Ｐ：抵抗土塊（水平部）による受動土圧（ｋＮ／ｍ）、Ｅ_Ａ：抵抗荷重の法面水平方向の力（ｋＮ／ｍ）、Ｅ_Ｐ：滑動荷重の法面水平方向の力（ｋＮ／ｍ）、δ：土塊と遮水材の層間摩擦角（°）、Ｆ_Ｓ：遮水材上の土塊滑りの安全率、Ｃ_ａ：土塊と遮水材の付着力（ｋＮ／ｍ）、Ｃ：土塊の粘着力（ｋＮ／ｍ）、φ：土塊の内部摩擦力（°） である。
【００６７】
全体モデルでは、このように底面部の土塊と受働土圧を考慮している。処分場底面にも遮水工を敷設する必要がある場合には、底面遮水工に沿った滑りがクリティカルになる場合がある。
【００６８】
図１０の検討断面におけるａ）下部遮水工と中間保護層、ｂ）上部遮水工と上部被覆層、ｃ）下部遮水工と遮水工全体の３断面に関して、全体モデルによる安定解析結果を図１３に示す。ここで、層間摩擦角δは、多層ライナー構造である遮水工の全体と覆土（中間保護層と上部被覆層）および下地との間で発揮される摩擦角と見なしている。ただし、外力として遮水工に作用する波圧の影響は、法面、底面からの反力Ｎ_Ａ、Ｎ_Ｐを低減させる様に働くと考えているが（図１２）、この安定解析では考慮していない。
【００６９】
不織布−シートおよびスラグ−不織布（水中）の層間摩擦角δ＝２７°が小さく（表２）、法勾配１：２ （傾斜角θ＝２６．６°）の遮水工全体の滑りについて支配的と考えられる。検討した３断面についてδ＝２７°に対する安全率Ｆｓは、それぞれａ） Ｆｓ＝１．８， ｂ）Ｆｓ＝１．４， ｃ）Ｆｓ＝２．２ である。これは、覆土と遮水工との摩擦抵抗力、覆土底面の土の摩擦抵抗力あるいは受働土圧が発揮され、側面遮水工の安定が確保されることを示している。一方、不織布−シートの層間摩擦角が小さくＦｓ＜１．０になる場合には、遮水工を補強して土塊の滑動力に抵抗するか、遮水材の発揮する引張力に期待して必要安全率を満たす必要がある。
【００７０】
＜側面遮水工のＦＥＭ解析＞
（１）解析条件
管理型海面処分場の側面遮水工（図１０）を対象として、２次元平面ひずみ弾塑性ＦＥＭ解析によって施工過程における遮水工の安定と多層ライナー構造の挙動を検討した。
【００７１】
土質材料は平面要素でモデル化し、法面部分は高さ・幅を約０．５ｍに分割した。材料モデルはＭｏｈｒ−Ｃｏｕｌｏｍｂの降伏側に従う弾塑性体とした。シート（ｔ＝３ｍｍ）と不織布（ｔ＝５ｍｍ）は、引張剛性だけもつ（曲げ剛性と圧縮剛性をもたない）部材として、非線形トラス要素でモデル化した。各材料の物性値は表１、表２に示した通りである。スラグ〜不織布、不織布〜シートの境界に弾塑性モデルの境界要素を配置し、一面せん断試験結果のシミュレーションから得たモデルパラメーターを用いた。なお、今回の検討範囲では、境界要素のメッシュサイズ依存性が無視できるくらい小さいことを事前計算により確認している。
境界条件として、裏込め石と基礎地盤との境界は固定境界、処分場側の側方境界は鉛直ローラーとした。シート・不織布の天端は、遮水工の天端位置に固定した。
【００７２】
＜検討条件＞に述べた施工過程に従った解析手順で段階解析を行った（計６１ステップ）。法面部の覆土層は高さ０．５ｍ毎（要素高さ）に平面要素を発生させ、その自重を作用させていく形で、段階的な盛土解析を行った。その間のシート・不織布の敷設段階で、非線形トラス要素を発生させた。
【００７３】
（２）解析結果（基本ケース）
ここでは、覆土の滑動力によって多層構造遮水工の各構成材に発生する引張力に着目し、層間せん断抵抗との相互作用を検討する。
上側不織布、下側不織布、シートのそれぞれに発生する引張力とこれらの合力について、天端から法面に沿った距離に対する分布を図１４に示す。法尻の位置は、下部遮水工ではＸ＝３７．５ｍ、上部遮水工ではＸ＝２９．７ｍである。ここでは、ａ）下部遮水工の中間保護層完了時（３９ステップ）、ｂ）下部遮水工の覆土▲９▼完了時、ｃ）上部遮水工の覆土▲９▼完了時（以降、最終時と称す）、の３通りについて示した。
【００７４】
全般的な傾向として、引張力の発生する範囲は上部法面だけである。ａ）とｂ）を比較すると、上部被覆層の荷重により下部遮水工の引張力が増加していき、引張力の発生する範囲が法面の約１／２から２／３に拡大している。また、ａ）とｃ）は類似の分布傾向を示すが、上部被覆層の方が中間保護層より法面の覆土厚が大きく、底面の覆土厚が薄いため、ｃ）の引張力が大きくなっている。
【００７５】
上側・下側不織布の引張力は、シートの引張力の１０倍程度大きく、全体の大部分の力を負担している。この基本ケースに関しては、上部・下部遮水工とも、また中間保護層完了時と最終時の両者ともこの傾向を示す。これは、層間の相対変位が比較的小さく、不織布の方がシートより弾性係数が高いためと考えられる。また、天端付近では、直接覆土層のせん断力を受ける上側不織布の方が下側不織布よりも大きい傾向を示すが、法面の途中では、ほぼ同様な大きさになっている。
【００７６】
なお、シート・不織布に発生しているひずみは、最大で１％程度であり、弾性範囲内にある。安定解析によるとＦｓ＞１．４を満足している断面に関して応力変形解析による照査を行ったが、基本ケースの設定条件に対しては、側面遮水工全体および構成材料の応力ひずみについて安定上問題ないと言える。
【００７７】
（３）パラメータースタディ
不織布〜シートの層間せん断強度と不織布の弾性係数に関してパラメータースタディを実施した。各ケースで得られた下部遮水工（最終時）の引張力分布を図１５〜１８に示す。
【００７８】
ａ）不織布〜シートの層間せん断強度の影響
上側・下側の不織布〜シートの層間せん断強度だけを変化させた場合について解析した。これは不織布〜シート間の摩擦係数を低下させた場合に相当する。上側・下側の不織布〜シートの層間せん断強度を基本ケースの０．５倍にすると、層間摩擦角ではφ＝２７．０°からφ＝１４．３°に低下させることに相当し、遮水工全体の安全率はＦｓ＝１．１になる（図１３）。直接土塊からせん断力を受ける上側不織布の引張力が基本ケースの２〜５倍程度大きくなり、下側不織布の分担する引張力は相対的に小さくなる。引張力の発生する範囲は法長の９０％程度となり、引張力の合力は４倍程度増加する（図１５）。一方、不織布〜シートの層間せん断強度を１．５倍にした場合（φ＝３７．４°）、すなわち、摩擦係数を上げた場合、大きな変化はないが、基本ケース（図１４ｂ）と比較した場合、基本ケースでは上側不織布の引張力が下側不織布より高くなっているが、層間せん断強度を１．５倍にした場合では上側不織布と下側不織布とで同等の引張力となっている。したがって、シートと下側不織布との摩擦係数を高くすれば下側不織布が引張力を分担する割合を増やしてシートにかかる引張力を減少させることができる。
【００７９】
極端なケースとして、上側・下側の不織布〜シートの層間せん断強度を基本ケースの０．０５倍にした場合（φ＝１．５°）、引張力の合力が基本ケースの２０倍程度に増加し、そのほとんどを上側不織布の引張力が負担している。これは、不織布の引張強さの１／２程度の値である。一方、下側不織布とシートには、基本ケースと同様な引張力しか生じていない（図１７）。
以上のことから、上側不織布とシートとのせん断強度は小さく、下側不織布とシートとのせん断強度は大きくすると、シートにかかる引張力は極力小さくすることができると考えられる。
【００８０】
ｂ）不織布の剛性の影響
上側・下側不織布の弾性係数を基本ケースの１／１０倍にしたケースの下部遮水工（最終時）の引張力分布を図１８に示す。不織布の引張力は、不織布の剛性に対してほぼ比例関係を示し、１／１０倍になった。上側・下側不織布の弾性係数を１０倍にした場合も上記と同様な傾向であった。
一方、シートの引張力は不織布の剛性に関係なくほぼ一定値であった。このため、不織布の剛性が低い時には相対的に大きな引張力をシートが負担し、反対に不織布の剛性が高い時には不織布が負担する引張力が大きくなると考えられる。したがって、シートより不織布の剛性（ヤング率）が高いほうがよいと考えられる。
【００８１】
実験３．
図１９に示すように、転炉スラグで作成した方面角度１：２、高さ５ｍの盛土斜面８１に、５００ｇ／ｍ^２、ヤング率３５０００ｋＮ／ｍ^２のポリエステル製長繊維不織布３１（保護材）と、３ｍｍの塩ビの遮水シート３２とを、保護マット３１〜遮水シート３２〜保護マット３１の順に積層し敷設した。遮水シート３２は下面をエンボス加工して摩擦係数を高くした。各材料の上端は遮水シート３２、保護マット３１を個別に斜面８１の上の固定部８４に固定し、個別に移動量を測定できるように各固定部にコイル式のエキスパンダー８２を設置した。遮水シート３２、保護マット３１を固定後に法面上端と同じ高さまで山砂８３を積み立てて遮水シート３２、保護マット３１の移動量を確認した。
【００８２】
評価方法として材料間の摩擦係数はＪＩＳ Ｋ７１２５を用いて各３回測定し最大値を採用した。
【００８３】
比較例として上下の保護マットに通常の５００ｇ／ｍ^２、ヤング率１５０００ｋＮ／ｍ^２の短繊維不織布とエンボス加工のない３ｍｍ塩ビ遮水シートを敷設しテストした。その結果を表３に示す。
【００８４】
【表３】

【００８５】
以上に示したように、本発明の実施例によれば、ヤング率が高い保護マット３１を使用し、また遮水シート３２の下面をエンボス加工して下側の保護マット３１との摩擦係数を大きくしたことにより、遮水シートの移動量を大幅に抑えることができ、また上側の保護マットの移動量も大幅に抑えることができた。
【００８６】
【発明の効果】
以上説明したように、請求項１記載の発明によれば、前記多層シートが、遮水シートとこの遮水シートの上下面にそれぞれ設けられた保護材とから３層以上に形成されているので、遮水シートが受ける負荷を遮水シートの上下面に設けられた保護材に分散してより一層、減ずることができる。
【００８７】
請求項２記載の発明によれば、前記中間保護層が土質材料からなるので、中間保護層の重量で、潮汐や波浪による楊圧力によって遮水シートが浮き上がるのを防ぐことができる。また、中間保護層として土質材料を用いても、中間保護層と遮水シートとの間には保護材が配置されるので、土質材料によって遮水シートが傷つくことが無い。
【００８８】
請求項３記載の発明によれば、請求項１記載の発明と同様の効果が得られることに加え、保護材のヤング率が遮水シートのヤング率よりも高いので、遮水構造にかかる引張力の多くを保護材が負担することとなり、遮水シートにかかる負荷を軽減することができる。
【００８９】
請求項４記載の発明によれば、請求項１〜３いずれか一項記載の発明と同様の効果が得られるのに加え、保前記保護材のヤング率が２００００ｋＮ／ｍ^２以上であることにより、保護材に載荷された荷重による保護材の変形を極力小さく抑え、遮水シートに与える応力を極力小さく抑えることができる。
【００９０】
請求項５記載の発明によれば、請求項１〜４いずれか一項記載の発明と同様の効果が得られるのに加え、前記遮水シートと下側の前記保護材との摩擦係数は上側の前記保護材との摩擦係数よりも大きいので、上側の保護材から遮水シートに伝達されるせん断応力を減少させ、また遮水シートにかかる引張力を下側の保護材に伝達しやすくなる。
【００９１】
請求項６記載の発明によれば、請求項１〜４いずれか一項記載の発明と同様の効果が得られるのに加え、遮水シートと下側の保護材とを接合した場合には、遮水シートと下側の保護材とを同時に敷設することができ、敷設時の工期を短縮することができる。また上側の保護材にかかるせん断力は遮水シートに伝達されにくく、遮水シートにかかる引張力は接合部から下側の保護材へ効果的に伝達されるので、遮水シートの負担する引張力を小さくすることができる。
【００９２】
さらに遮水シートと下側の保護材、及び遮水シートと上側の保護材とをそれぞれ接合して一体とした場合には、遮水シートと上下２枚の保護材とを全て同時に敷設することができ、更に敷設時の工期を短縮することができる。この場合、遮水シートと上側の保護材との接合に、水中で時間とともに接着効果が失われる接着剤を使用して施工後に接着が水中ではずれて上側の保護材にかかるせん断力が遮水シートに伝達されにくくする。
【００９３】
請求項７記載の発明によれば、請求項１〜７いずれか一項、特に請求項７記載の発明と同様の効果が得られる海面処分場の遮水構造を容易に施工することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態例を示す管理型廃棄物最終処理場（海面処分場）が造成される埋立予定地である。
【図２】図１の海面処分場の遮水構造を示す断面図である。
【図３】海面処分場１０の法面部分の断面のモデル図である
【図４】実験１の多層せん断実験（５層実験）の概念図である。
【図５】実験１の４層実験の構造図である。
【図６】実験１の４層実験におけるＦ_ｉ〜ｕ_１と Ｆ_２３（＝Ｆ_ｒ）〜ｕ_１の関係を示す図である。
【図７】実験２の５層実験におけるＦ_ｉ〜ｕ_１と Ｆ_２３（＝Ｆ_ｒ）〜ｕ_１の関係を示す図である。
【図８】実験１の４層構造の実験結果について荷重分担率Ｆ_ｉ ／ Ｆ_１〜せん断変位ｕ_１の関係を示す図である。
【図９】実験１の５層構造の実験結果について荷重分担率Ｆ_ｉ ／ Ｆ_１〜せん断変位ｕ_１の関係を示す図である。
【図１０】実験２で検討する管理型海面処分場の二重遮水シートから成る表面遮水工に関する検討断面図である。
【図１１】実験２の解析に用いたＰＶＣシート、長繊維不織布についての引張試験結果である。
【図１２】実験２で検討する底面図の土塊と受動土圧を考慮した安定解析のための全体モデルを示す図である。
【図１３】図１２の全体モデルによる安定解析結果を示す図である。
【図１４】実験２において、ａ）下部遮水工の中間保護層完了時、ｂ）中間保護層の覆土完了時、ｃ）最終時の、上側不織布、下側不織布、シートのそれぞれに発生する引張力とこれらの合力について、天端から法面に沿った距離に対する分布を示す図である。
【図１５】実験２において、不織布〜シートのφ＝１４．３°における最終時の引張力分布を示す図である。
【図１６】実験２において、不織布〜シートのφ＝３７．４°における最終時の引張力分布を示す図である。
【図１７】実験２において、不織布〜シートのφ＝１．５°における最終時の引張力分布を示す図である。
【図１８】実験２において、上側・下側不織布の弾性係数を基本ケースの１／１０倍にしたケースの下部遮水工の最終時の引張力分布を示す図である。
【図１９】実験３の装置を示す図である。
【図２０】従来の海面処分場の遮水構造を示す断面図である。
【符号の説明】
１ 埋立地
２ 水域
３ 既設護岸
４ 外周護岸
５ 中仕切護岸
６ 水処理施設
７ 海底面
１１ａ 腹付け土
１１ｂ 下地
１２ 上部被覆層
２０ 遮水構造
３０ 多層シート
３１ 保護マット（保護材）
３２ 遮水シート
４０ 中間保護層[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a water impermeable structure for a waste disposal site at a sea surface, and a water impermeable construction method for a sea surface disposal site.
[0002]
[Prior art]
As a water impermeable structure of a sea surface disposal site, there is a water impermeable structure using a synthetic resin water impermeable material such as rubber or PVC. It is described in the standards of the relevant government offices that when a synthetic resin-based water barrier material is used, a synthetic fibrous protective material such as a nonwoven fabric is used vertically. As shown in FIG. 20, the water-impervious sheet is doubled, an intermediate protective layer made of a nonwoven fabric or the like is laid between the two water-impervious sheets, and a protective mat for protecting the water-impervious sheet from the ground or soil material above and below. There is a need for a water-impervious structure laid. As the intermediate protective layer, a material such as a nonwoven fabric having a sufficient thickness and strength is used for the purpose of preventing the upper and lower water-impervious sheets from being simultaneously damaged by a load such as a landfill of waste.
[0003]
At the sea surface disposal site, a double layer of impermeable material will be laid, and a covering layer of soil material will be laid on it as a counterweight to prevent the impermeable structure from rising due to tide level and wave force. When constructing a water-blocking structure on the slope of the bottom surface of a sea surface disposal site, it is usually constructed with a slope of 1: 1.5 to 1: 3, and a shearing force due to the soil covering weight is applied to the entire water-blocking structure.
[0004]
In Patent Literature 1, a non-slip is provided on a surface of the protection mat that is in contact with the impermeable sheet to prevent the protection mat laid on the upper surface of the impermeable sheet from sliding down on the slope of the disposal site.
[0005]
[Patent Document 1]
JP 2001-314830 A
[0006]
[Problems to be solved by the invention]
By the way, according to the method of Patent Document 1, although the protective mat does not slide down, much of the load received by the protective mat based on the load of the upper coating layer and the input landfill waste is applied to the impermeable sheet. In the unlikely event that the impermeable sheet is damaged, it can be easily repaired on land. It was necessary to rebuild and re-submerge to re-create the impermeable structure.
[0007]
In the prior art, a non-woven fabric was used as a protective material (protective mat). However, the main purpose of the protective material is to prevent projections from piercing the water-impermeable sheet and tearing the water-impermeable sheet, so that the final covering is required. The influence of the generation of tension on the lower part due to the weight on the protective material and the synthetic resin waterproofing material could not be considered. When the final covering of the slope portion or the side portion of the water-blocking structure is laid, the nearest protective material is pulled down by friction to share the harmful load on the sheet. Therefore, in order to prevent stress deformation of the protective material, it is necessary to reduce the slope of the covering soil so as to ensure sufficient stability. Alternatively, it was necessary to take measures to prevent the collapse of the slope by reinforcing the protective material.
[0008]
It is an object of the present invention to provide a water-shielding structure for a sea surface disposal site that reduces the deformation of the water-impervious sheet by reducing the tensile force applied to the water-impervious sheet by covering soil or the like, and that is safe and easy to construct.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a method in which a multilayer sheet having a water-blocking sheet and a protective material is provided on at least a slope portion of a bottom surface having a slope of a sea surface disposal site via an intermediate protective layer. A water-blocking structure of a marine waste disposal site, which is laid double up and down and an upper covering layer is provided on an upper multilayer sheet,
The multilayer sheet is formed of three or more layers of a water-blocking sheet and protective materials provided on upper and lower surfaces of the water-blocking sheet.
[0010]
According to the first aspect of the present invention, since the multilayer sheet is formed in three or more layers from the water-impervious sheet and the protective materials provided on the upper and lower surfaces of the water-impervious sheet, the water-impervious sheet is received. The load can be further reduced by dispersing the load on the protective materials provided on the upper and lower surfaces of the water-blocking sheet.
[0011]
According to a second aspect of the present invention, there is provided a water shielding structure for a sea surface disposal site according to the first aspect, wherein the intermediate protective layer is made of a soil material.
[0012]
According to the second aspect of the present invention, since the intermediate protective layer is made of a soil material, the weight of the intermediate protective layer can prevent the impermeable sheet from rising due to the tangential force caused by tides and waves. Further, even if a soil material is used as the intermediate protective layer, since the protective material is disposed between the intermediate protective layer and the water impermeable sheet, the water impermeable sheet is not damaged by the soil material.
[0013]
The invention according to claim 3 is characterized in that the water-blocking structure of the sea surface disposal site according to claim 1 or 2 has a higher Young's modulus of the protective material than a Young's modulus of the water-blocking sheet.
[0014]
According to the third aspect of the invention, in addition to the same effect as the first aspect of the invention, since the Young's modulus of the protective material is higher than the Young's modulus of the impermeable sheet, the tensile force applied to the impermeable structure is increased. Most of the force is borne by the protective material, and the load on the impermeable sheet can be reduced.
[0015]
The invention according to claim 4 is the impermeable structure of the sea surface disposal site according to any one of claims 1 to 3, wherein the protective material has a Young's modulus of 20,000 kN / m.²It is characterized by the above.
[0016]
Here, the Young's modulus is obtained by a restraint tensile test using a biaxial tensile tester.
[0017]
According to the invention of claim 4, in addition to the same effect as the invention of any one of claims 1 to 3, the Young's modulus of the protective material is 20,000 kN / m.²Due to the above, the deformation of the protective material due to the load applied to the protective material can be suppressed as small as possible, and the stress applied to the water impermeable sheet can be suppressed as small as possible.
[0018]
The invention according to claim 5 is the impermeable structure of the sea surface disposal site according to any one of claims 1 to 4, wherein a coefficient of friction between the impermeable sheet and the lower protective material is the impermeable sheet. And a coefficient of friction between the protective material and the upper protective material.
[0019]
According to the fifth aspect of the invention, in addition to the same effect as the invention of any one of the first to fourth aspects, the coefficient of friction between the water-impervious sheet and the lower protective material is higher. Since the coefficient of friction with the protective material is larger than that of the protective material, the shear stress transmitted from the upper protective material to the impermeable sheet is reduced, and the tensile force applied to the impermeable sheet is easily transmitted to the lower protective material. .
[0020]
The invention according to claim 6 is the impermeable structure of the sea surface disposal site according to any one of claims 1 to 4, wherein the impermeable sheet is provided with the lower protective material, or the lower and upper parts. It is characterized in that it is partially or entirely joined to the protective material.
[0021]
According to the invention as set forth in claim 6, in addition to obtaining the same effects as the invention as set forth in any one of claims 1 to 4, when the waterproof sheet and the lower protective material are joined, The water-impervious sheet and the lower protective material can be laid at the same time, which saves labor and time required for laying. In addition, the shear force applied to the upper protective material is not easily transmitted to the waterproof sheet, and the tensile force applied to the waterproof sheet is effectively transmitted from the joint to the lower protective material. The force can be reduced.
[0022]
In addition, when the waterproof sheet and the lower protective material, and the waterproof sheet and the upper protective material are joined and integrated, respectively, the waterproof sheet and the upper and lower protective materials must be laid at the same time. In addition, the labor for laying can be omitted and the construction period can be shortened. In this case, an adhesive that loses its adhesive effect in water over time is used to join the waterproof sheet and the upper protective material. It is difficult to be transmitted to the seat.
[0023]
The invention according to claim 7 is a method for constructing a water impermeable structure of a sea surface disposal site according to any one of claims 1 to 6, wherein at least a part of a bottom surface having a slope of the sea surface disposal site. After laying the multilayer sheet, the laid multilayer sheet is covered with an intermediate protective layer made of a soil material, and the multilayer sheet is laid on the intermediate protective layer. When covering with a covering layer and laying a multilayer sheet, the water-impervious sheet and the lower protective material are joined together to lay the water-impervious sheet and the lower protective material at the same time, or the water-impervious sheet And the upper and lower protective materials are joined together, and the waterproof sheet and the upper and lower protective materials are laid at the same time.
[0024]
According to the seventh aspect of the present invention, it is possible to easily construct a water-blocking structure of a sea surface disposal site that can obtain the same effect as any one of the first to seventh aspects, particularly, the seventh aspect of the present invention.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, examples of the present invention will be specifically described, but the present invention is not limited to these.
[0026]
FIG. 1 is a landfill site where a managed waste disposal site (sea surface disposal site) according to an embodiment of the present invention will be constructed. An existing revetment 3 and an outer revetment 4 surround a part of the sea area 2 to construct a landfill adjacent to the landfill 1. The inside surrounded by the outer revetment 4 is further partitioned by a middle partition revetment 5. The section is the sea surface disposal site 10 using the embodiment of the present invention. A water treatment facility 6 is provided at one corner of the sea surface disposal site 10, and purifies water retained in the sea surface disposal site 10 before discharging it to the sea area 2.
[0027]
FIG. 2 is a cross-sectional view showing a water-blocking structure of the sea surface disposal site 10 of FIG. On the back surface (slope) of the partition wall 5, a flank soil 11 a and a ground 11 b covering the sea bottom 7 are provided. The padding soil 11a and the groundwork 11b are made of a soil material. As the soil material, mountain soil, stone material, slag, or the like can be used.
A water-blocking structure 20 (water-blocking work) is laid on the padding soil 11a and the base 11b, and is covered with the upper cover layer 12 (covering soil). The water-blocking structure 20 includes double multilayer sheets 30, 30 and an intermediate protective layer 40 interposed therebetween.
[0028]
FIG. 3 is a model diagram of a cross section of a slope portion of the sea surface disposal site 10. The multilayer sheet 30, the intermediate protective layer 40, the multilayer sheet 30, and the upper cover layer 12 are sequentially stacked on the padding soil 11 a and the base 11 b. The upper and lower multilayer sheets 30, 30 are each formed of a synthetic fibrous protective material (protective mat 31) and a synthetic resin water-blocking sheet 32 whose upper and lower surfaces are covered by the protective mats 31, 31.
[0029]
The Young's modulus of the protection mat 31 is desirably larger than the Young's modulus of the impermeable sheet, and is 20,000 kN / m.²Above, preferably 35,000 kN / m²Above, more preferably 45,000 kN / m²It is desirable that this is the case. Here, the Young's modulus is obtained by a restraint tensile test using a biaxial tensile tester. By increasing the Young's modulus of the protective material 31, the deformation of the protective material 31 due to the load applied to the protective material 31 can be suppressed as small as possible, and the stress applied to the water shielding sheet 32 can be suppressed as small as possible. As the protective mat 31, for example, a polyester long-fiber non-woven fabric or the like can be used, but other synthetic fiber long-fiber non-woven fabrics or woven fabrics may be used as long as they satisfy the above Young's modulus. .
[0030]
The water-impervious sheet 32 has a Young's modulus of 6000 kN / m so as to withstand the shear stress received from the protective material 31.²Above, preferably 6600 kN / m²It is desirable that this is the case. Similarly, the Young's modulus was obtained by a restrained tensile test using a biaxial tensile tester. As the water shielding sheet 32, a PVC sheet or the like can be used, but other synthetic resin sheets or the like may be used as long as they satisfy the above Young's modulus.
[0031]
Here, the coefficient of friction between the waterproof sheet 32 and the lower protective mat 31 may be designed to be larger than the coefficient of friction between the waterproof sheet 32 and the upper protective mat 31. By reducing the coefficient of friction between the water-blocking sheet 32 and the upper protection mat 31, the upper protection member receives much of the sliding force of the upper coating layer 12 applied downward in the slope direction. The transmitted shear stress is minimized. Further, by increasing the coefficient of friction between the water-impervious sheet 32 and the lower protective mat 31, the shear stress received by the water-impervious sheet 32 from the upper protective mat 31 is efficiently transmitted to the lower protective mat 31. Thus, the tensile force borne by the water impermeable sheet 32 can be reduced.
[0032]
As a method of reducing the coefficient of friction between the water impermeable sheet 32 and the upper protective material 31, there is a method of finishing the surface of the water impermeable sheet smoothly. In addition, there is a method of finishing the surface of the water-impermeable sheet smoothly and increasing the hardness of the water-impermeable sheet. Further, a method of flame-treating the surface of the upper protective material 31 to make it smooth, a method of providing a resin-made protrusion on the upper side of the water-impermeable sheet 32 to reduce the contact area, or a method of reducing the contact area with the water-impermeable sheet 32 and the upper protective material 31 There is a method of putting a lubricant between them. As a method for increasing the coefficient of friction between the water-impermeable sheet 32 and the lower protective material 31, a method of embossing the lower surface of the water-impermeable sheet 32 to make it uneven, or a method for increasing the unevenness of the water-impermeable sheet 32 and the lower protective material 31. There is a method such as putting a non-slip between them.
[0033]
Alternatively, the water impermeable sheet 32 and the protective material 31 may be partially or wholly joined. In the case of partial joining, point joining or line joining may be performed at many places.
As a joining method, a heat-sealing method may be used in which the surface of the impermeable sheet is melted by heat, and the fibers of the protective mat are pressed into the melted impermeable sheet surface by applying pressure. Alternatively, an acrylic adhesive (such as an adhesive made by Hirodine) which is decomposed by heat and generates tackiness may be used. As the adhesive, urethane-based, acrylic-based, rubber asphalt-based, epoxy-based adhesives and the like can be used. Alternatively, a mechanical bonding method may be used in which the surface of the water-impervious sheet is fluffed into, for example, a male material of a hook-and-loop fastener and entangled with the fibers of the protective mat.
[0034]
When the water shielding sheet 32 and the lower protective material 31 are joined, the shear stress received by the water shielding sheet 32 from the upper protective material 31 is efficiently transmitted from the joint to the lower protective material 31. Thus, the tensile force borne by the impermeable sheet 32 can be reduced.
Further, the water-impervious sheet and the lower protective material 31 can be laid at the same time, and the construction period at the time of laying can be shortened.
[0035]
When the water-impermeable sheet 32 and the lower protective material 31 are joined and the water-impermeable sheet 31 and the upper protective material 32 are joined and integrated, the water-impervious sheet 32 and the upper and lower protection materials are protected. The members 31, 31 can all be laid at the same time, and the construction period at the time of laying can be shortened.
If a water-soluble adhesive is used to join the water-blocking sheet 32 and the upper protective material 31, it will come off in water after construction. Even if it is not water-soluble, it tends to come off in water when bonded with an adhesive. Therefore, the shearing force applied to the upper protective material 31 is less likely to be transmitted to the waterproof sheet 32.
The water shielding sheet 32 and the lower protective material 31 are bonded to each other by using an adhesion method such as a heat bonding method or a mechanical bonding method that does not come off after construction, and is applied to the water shielding sheet 32. The tensile force is efficiently transmitted from the bonding portion to the lower protective member 31, and the tensile force borne by the water-blocking sheet 32 can be minimized.
[0036]
An intermediate protective layer 40 is formed between the multilayer sheets 30, 30. The upper covering layer 12 is formed on the upper multilayer sheet 30. As the intermediate protective layer 40 and the upper covering layer 12, a soil material can be used. When a soil material is used as the intermediate protective layer 40 and the upper covering layer 12, an effect of preventing the water-blocking structure 20 from rising against the Yangtze pressure due to the influence of waves and tides can be obtained.
As a soil material used for the intermediate protective layer 40 and the upper cover layer 12, mountain soil, stone materials, slag, and the like can be suitably used. In particular, when steel slag or copper slag having a large specific gravity is used, the volume of the intermediate protective layer 40 and the upper covering layer 12 required for submerging the water-blocking structure 20 into the sea can be reduced, and the limited site Waste disposal capacity can be increased.
[0037]
Next, a water-blocking construction method for installing the water-blocking structure 20 will be described. First, the belly soil 11a is installed on the back surface of the outer revetment 4, the ground 11b is installed so as to cover the sea bottom 7, and the lower multilayer sheet 30 is laid thereon. When the protective mat 31 and the waterproof sheet 32 constituting the multilayer sheet 30 are not bonded, the protective mat 31, the waterproof sheet 32, and the protective mat 31 are laid in this order. In addition, a non-slip or a lubricant may be appropriately inserted between the protection mat 31 and the water-blocking sheet 32.
[0038]
When the waterproof sheet 32 and the lower protective mat 31 are bonded, the bonded waterproof sheet 32 and the lower protective mat 31 are laid at the same time, and the protective mat 31 is overlaid thereon. To lay. Further, when the water impermeable sheet 32 is also bonded to the upper protection mat 31, the water impermeable sheet 32 and the protection mats 31, 31 bonded to the upper and lower surfaces thereof are laid at the same time.
[0039]
Next, an intermediate protective layer 40 is formed on the lower multilayer sheet 30. By forming the intermediate protective layer 40 made of a soil material, it is possible to prevent the lower multilayer sheet 30 from being lifted by the tide or the Yangtze pressure due to waves.
[0040]
After forming the intermediate protective layer 40, the upper multilayer sheet 30 is laid on the intermediate protective layer 40 in the same manner as the lower multilayer sheet 30. Thereafter, similarly to the intermediate protective layer 40, the upper cover layer 12 is formed on the upper multilayer sheet 30. By forming the upper covering layer 12, it is possible to prevent the upper and lower multilayer sheets 30, 30 and the intermediate protective layer 40 from floating due to the tide or the wave pressure caused by the waves.
[0041]
As described above, according to the present embodiment, the shear stress to the impermeable sheet 32 received from the sliding power downward on the slope by the intermediate protective layer 40 and the upper coating layer 12 on the upper protective mat 31 is minimized, Further, since the tensile force received by the seepage control sheet 32 is efficiently transmitted to the lower protective mat 31, the load on the seepage control sheet 32 can be minimized, and the construction of a safe and efficient sea surface disposal site can be achieved. It can be performed, and the stability of the slope at the time of use, that is, at the time of landfill of waste can be measured.
[0042]
【Example】
Hereinafter, experimental results showing the evaluation of the present invention will be described.
[0043]
Experiment 1. Load Transfer Characteristics of Geosynthetics Multilayer Liner Subjected to Shear Force
A multi-layer shearing device was developed for a partial model of a multi-layer liner (water-blocking structure) laid on the slope, and a slope model experiment of a geosynthetics multi-layer liner subjected to shearing force was performed.
[0044]
<Experimental method>
(1) Experimental equipment and principle
FIG. 4 shows a conceptual diagram (in the case of a five-layer structure) of the multilayer shear test apparatus. The shear box 51 (B188 mm × L288 mm × H150 mm) packed with the top layer (first layer) of the soil material 61 corresponds to the soil mass on the slope, and the shearing force F applied horizontally to the soil mass is the slip force due to the mass of the mass of the mass. Equivalent to. It is a partial structure model for the entire structure of the actual side seepage control, and the non-woven fabric 62 and the sheet 63 are fixed at their ends with fasteners, and are rigidly connected to the columns via hinged fittings. Fixed. The tension generated in each layer is measured with a load cell set at the fixed end. Between the fixed end of each layer and the rear end of the shear box (free length), elongation occurs freely according to the tensile force. Although the soil material 61 (lower earth tank 52) is illustrated as the boundary condition of the lowermost layer, stretch constraint (fixed) and free stretch (roller) can also be selected.
[0045]
In this experiment, the width of the sheet / nonwoven fabric specimen was set to 30 cm so that the effect of necking at the shearing portion was reduced with respect to the loading range (B = 188 mm or 240 mm) of the shearing portion. Further, a shear force was applied at a displacement speed of 50 mm / min until the displacement of the shear box became 150 mm. In the experiment using the first layer as a nonwoven fabric, a specimen in which the nonwoven fabric was bonded to a dummy plate (B240 mm × L340 mm) fixed to a shear box was used.
[0046]
(2) Shear force and shear stress between layers
In FIG. 4, a description will be given of a shear force and a shear stress acting between layers. In the case of a five-layer structure, the first layer: soil material 61 (shear box 51), the second layer: nonwoven fabric 62, the third layer: sheet 63, the fourth layer: nonwoven fabric 62, the fifth layer: soil material 61 (lower soil) Tank 52). The basic measurement items of the experiment are shear force F₁And the tensile force (i = 2, 3, 4, 4) generated in the i-th layer (sheet 63 / nonwoven fabric 62) and the displacement u of the shear box 51₁The relationship. F_rIs the shear force exerted by the fifth layer or the shear force F between the fourth and fifth layers.₄₅Which is obtained from the balance of the total force by the following equation.
F_r= F₁  −F₂  −F₃  −F₄                      (1)
[0047]
F_ijIs the interlayer shear force acting between the i-th layer and the j-th layer in contact. From the balance of the force of each layer, there is the following relationship, and the measured value F_i(I = 1 to 4).
F₁₂  = F₁
F₂₃  = F₁₂−F₂  = F₁−F₂                    (2)
F₃₄= F₂₃  −F₃  = F₁  −F₂  −F₃
F₄₅  = F₃₄  −F₄  = F₁  −F₂  −F₃  −F₄  = F_r
[0048]
Thus, the shear stress τ acting between the contacting i-th layer and the j-th layer_ijIs determined as follows.
τ_ij= F_ij/ A (A: contact area) (3)
[0049]
The displacement occurring at each arbitrary point in the i-th layer and the j-th layer is represented by u_i, U_jThen the relative displacement u between these two points_ijIs as follows.
u_ij= U_i  − U_j                                    (4)
[0050]
Shear force F₁  In the range where the action is effected, the displacement of the sheet / nonwoven fabric is the free length L_iElongation δL_iAnd the sum of the elongation immediately below the sheared portion. Also, the displacement of the soil material in the shear box does not always coincide with the displacement of the shear box. Here, for simplicity, the displacement of the first layer is directly measured by the displacement u of the shear box.₁  And Also, displacement u of the second to fourth layers_i  Is the elongation δL of the free length of each layer_iAnd
u_i    = ΔL_i  = F_i  / (EAs)_i  × L_i  (I> 1) (5)
Where (EAs)_iIs the tensile rigidity of the free length portion of the i-th layer, E is the Young's modulus, and As is the cross-sectional area.
[0051]
(3) Experimental case and experimental materials
For a prototype with a five-layer structure, a four-layer structure constituting a multilayer liner was tested. The constitutive material and the constraint condition (stretch constraint / free) of the lowermost layer were used as experimental parameters.
[0052]
A 3 mm-thick PVC sheet was used as a water-blocking sheet, a short-fiber nonwoven fabric and a long-fiber nonwoven fabric with a thickness of 5 mm equivalent as a protective mat, and a loose steelmaking slag having a relative density Dr = 50-60% as a soil material. These are materials that were studied for marine disposal sites.
[0053]
The tensile stiffness EAs of the experimental material was determined by applying a shear force to a shear box fixed to a sheet / non-woven fabric specimen using a dummy plate during the calibration of the test apparatus, and a shear force-displacement relationship, that is, a tensile force- It was measured from the relationship of the free length elongation. As a result, EAs was 4.22 kN for the sheet, EAs was 3.04 kN for the short-fiber nonwoven fabric, and 7.43 kN for the long-fiber nonwoven fabric. These values were used in equation (5).
[0054]
<Experimental results and discussion>
In this report, experimental results and considerations are given for the case of a four-layer or five-layer structure using a long-fiber nonwoven fabric.
[0055]
(1) Relationship between shear force / shear stress and displacement / relative displacement
a) Four-layer experiment
The first layer is a slag 65 packed in a shear box, the second layer is a long-fiber nonwoven fabric 62, the third layer is a sheet 63, and the fourth layer is a four-layer structure having a long-fiber nonwoven fabric 62. Stretching is free, and the fourth layer is under stretch constraint conditions (FIG. 5). Figure 6 shows the vertical stress σ_n= 30 (kN / m²F) obtained for₁~ U₁And F_ij~ U₁Show the relationship. F₃Is small, and the tensile force acting on the sheet 63 is extremely small. In addition, since the friction coefficients of the second and third layers and the third and fourth layers are not changed, F₂₃, F₃₄  (= F_r) Are very close to each other.
[0056]
b) Five-layer structure
In the five-layer structure, the first layer is a slag packed in a shear box, the second to fourth layers are made of long-fiber non-woven fabric-sheet-long-fiber non-woven fabric, and are freely stretchable. 4). In the five-layer experiment, σ_n= 30, 50 (kN / m²2) were carried out. Here, a large tensile force σ_n= 50 (kN / m²). FIG.₁~ U₁And F_ij~ U₁Show the relationship. F₃, F₄It can be seen that the tensile force acting on the sheet 63 and the long-fiber nonwoven fabric 62 of the fourth layer is extremely small.
Also, F₂₃, F₃₄, F₄₅(= F_r) Are very close to each other. F₁Is the maximum displacement is u₁= 30 mm, which is larger than the case of the four-layer structure. The vertical stress σ is higher in the five-layer experiment shown here._nIt is considered that the maximum shear force was increased and the elongation of each layer was increased due to the large. F₃> F₄This is considered to be due to both the difference in rigidity between the third and fourth layers and the difference in shear strength between the third and fourth layers and the fourth and fifth layers.
[0057]
(2) Load transmission rate
Shear force F in multi-layer shear experiment₁, The tensile force F generated in the i-th layer_iRatio F_i/ F₁Is defined as the load sharing ratio. Load sharing ratio F for experimental results of 4-layer and 5-layer structures_i/ F₁~ Shear displacement u₁8 and 9 are shown in FIGS.
For all four-layer and five-layer structures, the load transmissibility F₃/ F₁Is the smallest, and it can be seen that the long-fiber nonwoven fabric of the second layer bears most of the load.
[0058]
Experiment 2. FEM Analysis (Simulation) of Slope Slippage in Surface Impermeable Construction of Controlled Sea Surface Disposal Site
The purpose of this study is to develop a mechanical design method and a numerical analysis method based on the results of a model experiment (multi-layer shear test, experiment 1) conducted in the stability study on the side seepage control of a managed marine disposal site. The cross-section studied here is a surface impervious work using double impervious sheets, and the upper impervious works and lower impervious works are each composed of five layers of "soil material-nonwoven fabric-waterproof sheet-nonwoven fabric-soil material". (FIG. 2). First, a numerical analysis model was constructed for the shear characteristics between materials obtained from the single shear test, and this model was applied to the FEM analysis of the multilayer shear experiment to verify the validity of the numerical analysis method for the multilayer structure. Using this analysis method, the overall behavior of the side impermeable works at the sea surface disposal site was evaluated.
[0059]
<Consideration conditions>
(1) Cross section for study
FIG. 10 is a cross-sectional view of a study on the surface seepage control (water-seeding structure 20) composed of the double seepage control sheet of the managed sea surface disposal site in FIG. The pressure due to the waves penetrating the seawall around the seawall and the hydrostatic pressure due to the difference in water level inside and outside the landfill due to tide fluctuations act as lifting pressure on the seepage. In order to resist the lifting due to this lifting pressure, a structure is used in which both the intermediate protective layer and the upper covering layer of the surface water shield work are used as a load by using a soil material. The thicknesses of the intermediate protective layer 40 and the upper covering layer 12 are 3 m and 5 m, respectively, and the total thickness is 8 m. The sea conditions that determined this are design wave height Ho = 3.1 m, cycle T = 5.8 sec, water depth h = 14.5 m (MSL from the seabed ground), and tide level difference HWL-LWL: 3.6 m.
[0060]
The numbers in the drawing of FIG. 10 indicate the construction stage of the side seepage control work. (1) On the backside of the revetment, (1) a padding soil 11a, and (2) an underlayer (underlayer 11b) made of a soil material on the bottom surface, and (3) a lower water shield (multilayer sheet 30) is laid. After the intermediate protective layer 40 has been formed on the bottom surface and the side surface of the intermediate protection layer, the upper water shielding work (multilayer sheet 30) is laid. After the upper coating layer 12 is formed on the bottom surface and the side surface of [7], the soil is covered with [9]. Here, the upper and lower water shields each consist of a protection mat (long-fiber non-woven fabric), a water-proof sheet (PVC sheet), and a protection mat (long-fiber non-woven fabric), and a steelmaking slag (particle size of 30 mm or less) is used as a soil material. Consider using it.
[0061]
(2) Material properties
Tables 1 and 2 show physical property values relating to the deformation / strength characteristics of the materials used in the analysis.
Table 1 Deformation characteristics of materials
[Table 1]

Table 2 Shear strength characteristics of material (between)
[Table 2]

[0062]
FIG. 11 shows the results of a normal tensile test and a constrained tensile test performed on a PVC sheet and a long-fiber nonwoven fabric with a test piece size of 20 cm × 20 cm. Here, a biaxial tensile tester was used for the restraint tensile test. When laid in the soil, it was considered that necking would be restrained, and the elastic modulus obtained in the restraint tensile test was used.
It is assumed that the intermediate protective layer and the upper cover layer are mainly constructed in the sea, and if compaction is not performed, the relative density will be loosely deposited with a relative density of about Dr = 50 to 60%. The strength-deformation characteristics of the slag were obtained from a consolidation drainage triaxial compression test using a large specimen (dimension D300 mm × H600 mm) having an initial relative density Dr = 60%. The unit volume weight is as follows: air γ = 21 kN / m³, Underwater? '= 14 kN / m³(Steel Slag Association, Coastal Development Technology Research Center: “Steelmaking Slag User's Guide for Harbor Construction”, March 2000).
[0063]
(3) Stability analysis
From the stability analysis by the limit equilibrium method, the interlayer friction angle required for the impervious work at the study section (FIG. 10) was calculated. Since it is the limit equilibrium method, it is assumed that the maximum friction angle is simultaneously exerted along the sliding surface, ignoring the deformation and strain generated in the soil mass and the impermeable material.
[0064]
As a stability analysis model, a slope model for an existing slope part (RM Koerner: Designing with Geosynthetics-fourth edition, Prentice Hall, Chapter 5 Designing, J.E.D., G.E. F. Beech: Stability of soil layers on geosynthetic lining system, Proceedings of Geosynthetics '89, Vol. 1, pp. 35-46, 1989.
[0065]
In FIG. 12, the following equation holds.
N_A  = W_Acosβ-F
N_P  = W_P  + E_P  sinβ-F ′
E_A  sinβ = W_A  −N_A  cosβ − (N_A  tanδ + C_a  ) Sinβ / F_S
E_P  cosβ = (N_P  tanδ + C) / F_S  + A_P
E_A  = E_P
[0066]
Where W_A: Gross weight of sliding mass (kN / m), W_P： Total weight of resistive mass (kN / m), N_A: Reaction force (kN / m) in the vertical direction of the slope, N_P: Reaction force (kN / m) in the direction perpendicular to the bottom surface, β: normal gradient (°), F: wave pressure applied to the bottom surface (kN / m), F ′: wave pressure applied to the bottom surface (kN / m), P_P： Passive earth pressure (kN / m) by resistance earth mass (horizontal part), E_A: Force in the horizontal direction of the slope of resistance load (kN / m), E_P: Sliding load horizontal force (kN / m), δ: Interlaminar friction angle (°) between soil mass and impermeable material, F_S: Safety factor of clods sliding on impermeable material, C_a: Adhesive force (kN / m) between the soil mass and the impermeable material, C: adhesive force (kN / m) of the soil mass, φ: internal friction force (°) of the earth mass.
[0067]
In the overall model, the soil mass at the bottom and the passive earth pressure are thus considered. If it is necessary to lay a seepage control on the bottom of the disposal site, sliding along the bottom view may be critical.
[0068]
Stability analysis results of the entire model for three cross-sections of a) the lower water shield and the intermediate protective layer, b) the upper water shield and the upper cover layer, and c) the lower water shield and the water shield in the study cross section of FIG. Is shown in FIG. Here, the interlayer friction angle δ is regarded as a friction angle exerted between the entire water-blocking construction having a multilayer liner structure, the soil (the intermediate protective layer and the upper coating layer), and the foundation. However, the effect of the wave pressure acting on the water shield as external force is due to the reaction force N from the slope and the bottom._A, N_P(FIG. 12), but is not considered in this stability analysis.
[0069]
Interlaminar friction angle δ = 27 ° between nonwoven fabric-sheet and slag-nonwoven fabric (underwater) is small (Table 2), and it is dominant in the slippage of the entire impermeable structure with a normal gradient of 1: 2 (tilt angle θ = 26.6 °). it is conceivable that. The safety factors Fs for δ = 27 ° for the three cross sections examined are a) Fs = 1.8, b) Fs = 1.4, c) Fs = 2.2, respectively. This indicates that the frictional resistance between the soil covering and the impervious construction, the frictional resistance of the soil on the bottom of the soil covering or the passive earth pressure is exerted, and the stability of the side impermeable construction is ensured. On the other hand, in the case where the non-woven fabric-sheet has a small interlayer friction angle of Fs <1.0, it is expected that the waterproofing work will be reinforced to resist the sliding power of the earth mass or the tensile force exerted by the waterproofing material. It is necessary to meet the required safety factor.
[0070]
<FEM analysis of side wall impermeable works>
(1) Analysis conditions
The stability of the seepage control work and the behavior of the multilayer liner structure during the construction process were examined by two-dimensional plane strain elasto-plastic FEM analysis for the side seepage control work (Fig. 10) of the managed sea surface disposal site.
[0071]
The soil material was modeled by a plane element, and the slope portion was divided into a height and width of about 0.5 m. The material model was an elasto-plastic body following the Mohr-Coulomb yield side. The sheet (t = 3 mm) and the nonwoven fabric (t = 5 mm) were modeled by nonlinear truss elements as members having only tensile stiffness (without bending stiffness and compression stiffness). The physical properties of each material are as shown in Tables 1 and 2. The boundary element of the elasto-plastic model was arranged at the boundary between the slag and the nonwoven fabric, and between the nonwoven fabric and the sheet, and the model parameters obtained from the simulation of the results of the one-sided shear test were used. In addition, in the present study range, it has been confirmed in advance that the mesh size dependence of the boundary element is negligibly small.
As boundary conditions, the boundary between the backfill stone and the foundation ground was a fixed boundary, and the lateral boundary on the disposal site side was a vertical roller. The top of the sheet / non-woven fabric was fixed at the top of the water shield.
[0072]
The stage analysis was performed by the analysis procedure according to the construction process described in <Consideration conditions> (total 61 steps). The earth covering layer on the slope portion was subjected to a stepwise embankment analysis by generating a plane element every 0.5 m (element height) and applying its own weight. In the meantime, a non-linear truss element was generated during the laying of the sheet and nonwoven fabric.
[0073]
(2) Analysis results (basic case)
Here, the interaction with the shear resistance between layers is examined, focusing on the tensile force generated in each component of the multi-layer structure water-blocking works due to the sliding power of the soil covering.
FIG. 14 shows the distribution of the tensile force generated in each of the upper nonwoven fabric, the lower nonwoven fabric, and the sheet and the resultant force with respect to the distance along the slope from the top end. The position of the butt is X = 37.5 m for the lower impermeable structure and X = 29.7 m for the upper impermeable structure. Here, a) at the time of completion of the intermediate protective layer of the lower seepage control (39 steps), b) at the completion of the soil cover at the lower seepage control [9], c) at the completion of the cover of the upper seepage control [9] (hereinafter, 3) are shown.
[0074]
As a general trend, the only area where the tensile force occurs is the upper slope. Comparing a) and b), the tensile force of the lower water shield increases due to the load on the upper coating layer, and the range in which the tensile force is generated expands from about 1/2 to 2/3 of the slope. I have. Further, a) and c) show a similar distribution tendency, but the upper cover layer has a larger soil cover thickness on the slope than the intermediate protective layer and a smaller cover soil thickness on the bottom surface, so that the tensile force of c) becomes larger. ing.
[0075]
The tensile force of the upper and lower nonwoven fabrics is about 10 times greater than the tensile force of the sheet, and bears most of the entire force. Regarding this basic case, both upper and lower impervious works, and both the completion and final stages of the intermediate protective layer show this tendency. This is probably because the relative displacement between the layers is relatively small, and the nonwoven fabric has a higher elastic modulus than the sheet. In addition, near the top end, the upper nonwoven fabric that is directly subjected to the shearing force of the soil cover layer tends to be larger than the lower nonwoven fabric, but has almost the same size in the middle of the slope.
[0076]
In addition, the strain generated in the sheet / nonwoven fabric is about 1% at the maximum, and is within the elastic range. According to the stability analysis, cross-sections satisfying Fs> 1.4 were checked by stress-deformation analysis. No problem.
[0077]
(3) Parameter study
A parameter study was performed on the interlaminar shear strength of the nonwoven fabric to the sheet and the elastic modulus of the nonwoven fabric. 15 to 18 show the tensile force distribution of the lower water shield (final time) obtained in each case.
[0078]
a) Effect of interlaminar shear strength between nonwoven fabric and sheet
The case where only the interlayer shear strength between the upper and lower nonwoven fabrics to the sheet was changed was analyzed. This corresponds to a case where the friction coefficient between the nonwoven fabric and the sheet is reduced. If the interlaminar shear strength of the upper and lower nonwoven fabrics and sheets is 0.5 times that of the basic case, the interlaminar friction angle is reduced from φ = 27.0 ° to φ = 14.3 °, which is equivalent to water impermeability. The safety factor of the entire construction is Fs = 1.1 (FIG. 13). The tensile force of the upper nonwoven fabric, which is directly subjected to the shearing force from the earth mass, is about 2 to 5 times larger than that of the basic case, and the tensile force shared by the lower nonwoven fabric is relatively small. The range in which the tensile force occurs is about 90% of the law length, and the resultant force of the tensile force increases about four times (FIG. 15). On the other hand, when the interlaminar shear strength between the nonwoven fabric and the sheet was increased by 1.5 times (φ = 37.4 °), that is, when the friction coefficient was increased, there was no significant change, but compared with the basic case (FIG. 14B). In this case, in the basic case, the tensile force of the upper nonwoven fabric is higher than that of the lower nonwoven fabric, but when the interlaminar shear strength is increased by 1.5 times, the tensile force of the upper nonwoven fabric and the lower nonwoven fabric are equivalent. Therefore, if the coefficient of friction between the sheet and the lower nonwoven fabric is increased, the ratio of the lower nonwoven fabric sharing the tensile force can be increased, and the tensile force applied to the sheet can be reduced.
[0079]
As an extreme case, when the interlaminar shear strength between the upper and lower nonwoven fabrics and sheets is 0.05 times that of the basic case (φ = 1.5 °), the resultant tensile force increases to about 20 times that of the basic case. Most of the stress is borne by the tensile force of the upper nonwoven fabric. This is a value of about 1/2 of the tensile strength of the nonwoven fabric. On the other hand, only the tensile force similar to that of the basic case is generated in the lower nonwoven fabric and the sheet (FIG. 17).
From the above, it is considered that when the shear strength between the upper nonwoven fabric and the sheet is small and the shear strength between the lower nonwoven fabric and the sheet is large, the tensile force applied to the sheet can be reduced as much as possible.
[0080]
b) Effect of rigidity of non-woven fabric
FIG. 18 shows the tensile force distribution of the lower water shield (final time) of the case where the elastic coefficient of the upper and lower nonwoven fabrics is 1/10 times that of the basic case. The tensile force of the nonwoven fabric was almost proportional to the rigidity of the nonwoven fabric, and was 1/10 times. When the elastic modulus of the upper and lower nonwoven fabrics was increased by a factor of 10, the same tendency as described above was observed.
On the other hand, the tensile force of the sheet was almost constant regardless of the rigidity of the nonwoven fabric. Therefore, when the rigidity of the nonwoven fabric is low, the sheet bears a relatively large tensile force, and when the rigidity of the nonwoven fabric is high, the tensile force that the nonwoven fabric bears is increased. Therefore, it is considered that the higher the rigidity (Young's modulus) of the nonwoven fabric than the sheet is better.
[0081]
Experiment 3.
As shown in FIG. 19, 500 g / m of embankment slope 81 having a direction angle of 1: 2 and a height of 5 m made of converter slag was used.², Young's modulus 35,000 kN / m²Polyester long fiber nonwoven fabric 31 (protective material) and a 3 mm PVC waterproof sheet 32 were laminated and laid in the order of protective mats 31 to 32 and protective mats 31. The water shielding sheet 32 was embossed on the lower surface to increase the friction coefficient. At the upper end of each material, the water-impervious sheet 32 and the protective mat 31 were individually fixed to a fixing portion 84 on a slope 81, and a coil-type expander 82 was installed at each fixing portion so that the amount of movement could be measured individually. After fixing the water-impervious sheet 32 and the protection mat 31, piles 83 were piled up to the same height as the upper end of the slope, and the movement amount of the water-impervious sheet 32 and the protection mat 31 was confirmed.
[0082]
As an evaluation method, the friction coefficient between the materials was measured three times using JIS K7125, and the maximum value was adopted.
[0083]
As a comparative example, a normal 500 g / m 2², Young's modulus 15000 kN / m²Was tested by laying a short-fiber nonwoven fabric and a 3 mm PVC waterproof sheet without embossing. Table 3 shows the results.
[0084]
[Table 3]

[0085]
As described above, according to the embodiment of the present invention, the protective mat 31 having a high Young's modulus is used, and the lower surface of the water shielding sheet 32 is embossed to reduce the coefficient of friction with the lower protective mat 31. By increasing the size, the amount of movement of the impermeable sheet was significantly reduced, and the amount of movement of the upper protective mat was also significantly reduced.
[0086]
【The invention's effect】
As described above, according to the first aspect of the present invention, the multilayer sheet is formed of three or more layers from the water-blocking sheet and the protective materials provided on the upper and lower surfaces of the water-blocking sheet. In addition, the load received by the water impermeable sheet can be further reduced by dispersing the load on the protective materials provided on the upper and lower surfaces of the water impermeable sheet.
[0087]
According to the second aspect of the present invention, since the intermediate protective layer is made of a soil material, the weight of the intermediate protective layer can prevent the impermeable sheet from rising due to the tangential force caused by tides and waves. Further, even if a soil material is used as the intermediate protective layer, since the protective material is disposed between the intermediate protective layer and the water impermeable sheet, the water impermeable sheet is not damaged by the soil material.
[0088]
According to the third aspect of the invention, in addition to the same effect as the first aspect of the invention, since the Young's modulus of the protective material is higher than the Young's modulus of the impermeable sheet, the tensile force applied to the impermeable structure is increased. Most of the force is borne by the protective material, and the load on the impermeable sheet can be reduced.
[0089]
According to the invention of claim 4, in addition to the same effect as the invention of any one of claims 1 to 3, the Young's modulus of the protective material is 20,000 kN / m.²Due to the above, the deformation of the protective material due to the load applied to the protective material can be suppressed as small as possible, and the stress applied to the water impermeable sheet can be suppressed as small as possible.
[0090]
According to the fifth aspect of the invention, in addition to the same effect as the invention of any one of the first to fourth aspects, the coefficient of friction between the water-impervious sheet and the lower protective material is higher. Since the coefficient of friction with the protective material is larger than that of the protective material, the shear stress transmitted from the upper protective material to the impermeable sheet is reduced, and the tensile force applied to the impermeable sheet is easily transmitted to the lower protective material. .
[0091]
According to the invention as set forth in claim 6, in addition to obtaining the same effects as the invention as set forth in any one of claims 1 to 4, when the waterproof sheet and the lower protective material are joined, The water-impervious sheet and the lower protective material can be laid at the same time, and the construction period at the time of laying can be shortened. In addition, the shear force applied to the upper protective material is not easily transmitted to the waterproof sheet, and the tensile force applied to the waterproof sheet is effectively transmitted from the joint to the lower protective material. The force can be reduced.
[0092]
In addition, when the water-blocking sheet and the lower protective material, and the water-blocking sheet and the upper protective material are joined and integrated, respectively, the water-blocking sheet and the two upper and lower protective materials must be laid at the same time. And the construction period at the time of laying can be shortened. In this case, an adhesive that loses its adhesive effect in water over time is used to join the waterproof sheet and the upper protective material. It is difficult to be transmitted to the seat.
[0093]
According to the seventh aspect of the present invention, it is possible to easily construct a water-blocking structure of a sea surface disposal site that can obtain the same effect as any one of the first to seventh aspects, particularly, the seventh aspect of the present invention.
[Brief description of the drawings]
FIG. 1 is a landfill site where a managed waste final disposal site (sea surface disposal site) according to an embodiment of the present invention will be constructed.
FIG. 2 is a cross-sectional view showing a water shielding structure of the sea surface disposal site of FIG.
FIG. 3 is a model diagram of a cross section of a slope portion of the sea surface disposal site 10.
FIG. 4 is a conceptual diagram of a multi-layer shear experiment (five-layer experiment) of Experiment 1.
FIG. 5 is a structural diagram of a four-layer experiment of Experiment 1.
FIG. 6 shows F in the four-layer experiment of Experiment 1._i~ U₁And F₂₃(= F_r) -U₁FIG.
FIG. 7 shows F in the five-layer experiment of Experiment 2._i~ U₁And F₂₃(= F_r) -U₁FIG.
FIG. 8 shows the load sharing ratio F with respect to the experimental result of the four-layer structure of Experiment 1._i/ F₁~ Shear displacement u₁FIG.
FIG. 9 shows the load sharing ratio F for the experimental result of the five-layer structure of Experiment 1._i/ F₁~ Shear displacement u₁FIG.
FIG. 10 is a cross-sectional view of a study on a surface impervious work composed of a double impervious sheet of a managed sea surface disposal site to be examined in Experiment 2.
FIG. 11 shows the results of a tensile test on a PVC sheet and a long-fiber nonwoven fabric used in the analysis of Experiment 2.
FIG. 12 is a diagram showing an overall model for stability analysis in consideration of the earth mass and passive earth pressure in the bottom view studied in Experiment 2.
FIG. 13 is a diagram showing a result of stability analysis based on the overall model of FIG. 12;
[FIG. 14] In Experiment 2, the upper nonwoven fabric, the lower nonwoven fabric, and the sheet are generated at a) when the intermediate protective layer of the lower water shield works is completed, b) when soil covering of the intermediate protective layer is completed, and c) at the end. It is a figure which shows the distribution with respect to the distance along the slope from a top about a tensile force and these resultant forces.
FIG. 15 is a diagram showing a final tensile force distribution of φ14.3 ° between the nonwoven fabric and the sheet in Experiment 2.
FIG. 16 is a diagram showing a tensile force distribution at the final time of φ = 37.4 ° between the nonwoven fabric and the sheet in Experiment 2.
FIG. 17 is a diagram showing a tensile force distribution at the final time of φ = 1.5 ° between the nonwoven fabric and the sheet in Experiment 2.
FIG. 18 is a diagram showing a tensile force distribution at the end of a lower water shield in a case in which the elastic modulus of the upper and lower nonwoven fabrics is 1/10 times that of the basic case in Experiment 2.
FIG. 19 is a diagram showing an apparatus of Experiment 3.
FIG. 20 is a cross-sectional view showing a water-blocking structure of a conventional sea surface disposal site.
[Explanation of symbols]
1 landfill
2 water area
3 Existing revetments
4 Perimeter seawall
5 Middle partition seawall
6 water treatment facilities
7 Sea floor
11a Soil
11b underlay
12 Upper coating layer
20 Waterproof structure
30 multilayer sheet
31 Protective mat (protective material)
32 impermeable sheet
40 Intermediate protective layer

Claims (7)

A multilayer sheet having a water-impervious sheet and a protective material is laid up and down doubly over an intermediate protective layer on at least a slope portion of a bottom surface having a slope of a sea surface disposal site, and a top cover is formed on the upper multilayer sheet. A water-impervious structure of a sea surface waste disposal site where layers are provided,
The water shielding structure of a sea surface disposal site, wherein the multilayer sheet is formed of three or more layers from a water shielding sheet and protective materials provided on upper and lower surfaces of the water shielding sheet, respectively. The water impermeable structure of a sea surface disposal site according to claim 1, wherein the intermediate protective layer is made of a soil material. 3. The water shielding structure for a sea surface disposal site according to claim 1, wherein the Young's modulus of the protective material is higher than the Young's modulus of the water shielding sheet. Water-impervious structure of sea disposal site according to any one of claims 1-3, wherein the Young's modulus of the protective material is 20000kN / m ² or more. The sea surface according to any one of claims 1 to 4, wherein a coefficient of friction between the waterproof sheet and the lower protective material is larger than a coefficient of friction between the waterproof sheet and the upper protective material. The impermeable structure of the disposal site. The sea surface according to any one of claims 1 to 4, wherein the water-impervious sheet is partially or entirely bonded to the lower protective material or the lower and upper protective materials. The impermeable structure of the disposal site. A sea surface disposal site impermeable construction method used when constructing the sea surface disposal site impermeable structure according to any one of claims 1 to 6,
After laying the multilayer sheet on at least a slope portion of a bottom surface having a slope of the sea surface disposal site, the laid multilayer sheet is covered with an intermediate protective layer made of a soil material, and the multilayer sheet is placed on the intermediate protective layer. Laying, laying on the laid multilayer sheet with an upper covering layer made of a soil material, and, when laying the multilayer sheet, joining the water-impervious sheet and the lower protective material, and A lower surface protection material is laid at the same time, or a water barrier sheet and upper and lower protection materials are joined, and the water protection sheet and the upper and lower protection materials are laid at the same time. Water construction method.

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