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THE REINFORCEMENT AND CONSTRUCTION METHOD FOR EMBANKMENT BY USING LOW QUALITY SURPLUS SOIL AND MUNICIPAL WASTE INCINERATOR ASHES Nagasaki University H.

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Presentation on theme: "THE REINFORCEMENT AND CONSTRUCTION METHOD FOR EMBANKMENT BY USING LOW QUALITY SURPLUS SOIL AND MUNICIPAL WASTE INCINERATOR ASHES Nagasaki University H."— Presentation transcript:

1 THE REINFORCEMENT AND CONSTRUCTION METHOD FOR EMBANKMENT BY USING LOW QUALITY SURPLUS SOIL AND MUNICIPAL WASTE INCINERATOR ASHES Nagasaki University H. Sakanoshita Y. Tanabashi Y. Jiang S.Sugimoto K.Ogawa

2 研究の背景 Back ground of research  Difficult for usage  Remarkable rise of disposal cost  Limit of the disposal space  Increase rapidly with the economic growing  Risk of environmental pollution  Lack of the disposal space Municipal solid waste incinerator ashes (MSWI ashes) The resource recycling of them is an urgent problem Low quality sludge (Ariake clay)

3 研究の目的 Purpose of research MSWI ashes Ecoash Low quality sludge disposed to harmless New type construction material Mixture Mechanical characterization Chemical characterization Evaluation pavement and filling material Evaluation of usability Integral construction numerical simulation centrifugal model experiment

4 リサイクルシステム Storage equipment Fixed quantity supply equipment Dryness equipment Exhaust gas Activated carbon adsorption Dust collector Melting equipment Fly ash Exhaust gas Crusher The magnetic separator Crusher The first processing ashes tank The second response equipment Product tank Production The first response equipment Chimney Decomposition of dioxin Stabilization of heavy metals Decomposition of dioxin Additives A Stabilization of heavy metals Additives B Processing flow of recycling system

5 エコアッシュの物性値 The characteristics of Ecoash PropertiesUnit Nagasaki Ecoash (N) Saga Ecoash (S) Soil particle density ρsρs (g/cm 3 ) Grain occasion distribution Sand(%) Silt(%) Clay(%) Optimum moisture content W opt (%) Maximum dry content ρ dmax (g/cm 3 )

6 有明粘土の物性値 The characteristics of Low Quality Surplus Soil PropertiesUnitAriake ClayHasuike Clay Salt content(mg/kg) Soil particle densityρsρs (g/cm 3 ) Natural water content WnWn (%) Liquid limitWLWL (%) Plastic limitWPWP (%) Grain size distribution Sand(%)382.3 Silt(%) Clay(%)

7  Water content of Ariake clay W ≒ 139 %  Saga Ecoash : Ariake clay = 50 : 50  Ratio of the slaked lime R L = 0 , 1 , 2 , 5 % RL=5%RL=5% RL=1%RL=1% Target strength 300kPa 一軸圧縮試験結果 Results of the unconfined compression test Mixing condition Slaked lime addition is an important factor

8 重金属溶出試験 Heavy metals leaching test ItemCdPbCr 6+ As T ‐ Hg Se The welfare ministry standard<0.001<0.01<0.05<0.01<0.0005<0.01 Nagasaki Ecoash , N < (T-Cr)<0.001< Saga Ecoash , S <0.001 <0.005(T-Cr)<0.001< <0.001 Ariake clay , A <0.001 <0.005(Cr 5+ )0.008< <0.001 Hasuike , H < (Cr 5+ )0.017< <0.001 NA Age 14th< (T-Cr)<0.001< Age 28th< (T-Cr)<0.001< NH Age 14th< (T-Cr)<0.001< Age 28th< (T-Cr)<0.001< SA Age 14th< (T-Cr)<0.001< Age 28th< (T-Cr)<0.001< SH Age 14th< (T-Cr)<0.001< Age 28th< (T-Cr)<0.001< Possible to suppress the elution of heavy metals

9 Experiment on age 14 days 遠心模型実験概要 Centrifugal model Experiment preparation 50cm wide , 14cm deep 40m wide , 11.2m deep Real ground scale Model scale Saga Ecoash : Ariake Clay = 50 : 50 , Ratio of the slaked lime R L = 1 % Improvement layer and Filling are made Experimental device ×80 80G Experiment on age 14 days

10 Clay layer Clay layer with water content about 100% is prepared 模型地盤概要図 Outline of model ground (Unit : mm) Earth pressure gauge (1) (2)(3) Gradient of slope 1 : 0.6 D Improvement Fill Loading plate B Cut out clay layer and construct improvement and Fill after self-weight consolidation Loading Loading plate descends with a rate of 0.05mm/s while acting centrifugal acceleration of 80G

11 Experiment cases CaseImprovementFillBreadth B (m) Depth D (m) N× ○ 00 SS ○○ 11.5(short)1(shallow) LS ○○ 15.4(Long)1(shallow) LD ○○ 15.4(Long)1.5(Deep) Fill Improvement Clay layer B D B D B D

12 荷重強度 - 土圧関係① Load-earth pressure(1) Failure Case N (1 ) (2 ) (3 ) Earth pressure gauge(2) Earth pressure gauge(1) Earth pressure gauge(3) Unimproved Fill is not stable

13 荷重強度 - 土圧関係② Load-earth pressure(2) Case SS Case LS Case LD Earth pressure gauge(2) (2 ) Breadth is small It cannot spread load Case SS Touch area is large Case LS , Case LD The friction effect is large

14 荷重強度 - 沈下量関係 Load-settlement curve Settlement depression effect Large Small Case NCase SSCase LS Case LD

15 数値解析概要① Outline of analytical model (1) Yield criterion Mohr-Coulomb Analysis procedure Construct clay Cut out clay layer Construct improvement and fill Loading Analysis code FLAC3D Loading method 60kPa loadings (By 6 stages, each of 10kPa) A clay layer model with surface reinforced is assumed as 80 times of centrifugal model.

16 数値解析概要② Outline of analytical model (2) PropertiesClay layer Improvement & Fill Density (g/cm 3 ) Cohesion (kPa) Angle of internal friction (°)017.1 Tensile creep (kPa) Angle of dilatancy (°)02 Volumetric elastic coefficient (kPa) Elastic shear coefficient (kPa) Analytical Cases The same as experiment case Analytical physical property

17 破壊領域 Failure region (before loading) Case SS Case LS Concentration of stress None Shear Tension Tension failure in the early stage Case LS Improvement loses bearing capacity Failure region (after loading 60 k Pa)

18 解析ケース Numerical simulation case Case (b/D) Breadth b Depth D (m) 0/ / / / / / /

19 荷重強度 - 沈下量関係 Load-settlement curve 7.7/ /1.0 The lower end breadth of filling is smaller than the breadth of the improvement, therefore the settlement depression effect is small. 5.8/ /1.0 The settlement depression effect by the extension of improvement depth D is large

20 Could be used as a high performance geo-material 結論 Conclusions Mixture (Ecoash , Low quality sludge , Slaked lime)  Sufficient strength  Chemical stable and harmless to public health Centrifugal model experiment & Numerical analysis  Fill was steady by integral construction with pavement Mechanical characterization & Chemical characterization Integral construction is effective

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22 荷重強度 - 沈下量関係 Load strength – settlement curve Case SS Case LS SS ( Analysis ) SS ( Experiment ) SS ( Analysis ) SS ( Experiment ) LS ( Experiment ) LS ( Analysis ) Effect of tension failure is large LS ( Analysis ) Settlement is larger than Case SS The slippage was not generated in the boundary in clay layer and improvement Analysis Displacement is small

23 pH 測定試験 pH measurement test Ecoash/clay mixture Slaked lime Ecoash Hasuike clay Ariake clay pH PbCl 2 + Ca(OH) 2 →Pb(OH) 2 + CaCl 2 2Na 3 AsO 4 + 3Ca(OH) 2 →Ca 3 (AsO 4 ) 2 + 6NaO 12.2 Ecoash/clay mixture can be purification effect of the soil pollution and oxidation depression effect.

24 表層改良工法 The surface layer improvement Soft ground Bearing stratum Surface layer improvement Ariake clay Side floating tubercle Bearing stratum unimproved Ecoash Slaked lime Ariake clay improvement Soft ground

25 (ダイオキシン類分解メカニズ ム) DXNs 分解 HCl ガス発生 原灰 粉砕灰+ 添加剤 A( 石灰系) CaO+HCl→CaCl 2 +H 2 O 熱の流れ HC lガスの流 れ CaCl2 : 融点 772℃ 焼成炉温度: 772℃以上: CaCl 2 液化 再合成しやすい 772℃以下: CaCl 2 固体 → 安定

26 《重金属類固定化メカニズム》 ( 鉛固定化メカニズム) ①硫化反応: PbCl 2 + Na 2 S → PbS + 2NaCl ②水酸化反応: 加水混練による処理灰中石灰分のイオン化 Pb Cl - + Ca (OH) - → Pb(OH) 2 + CaCl 2 ( OH ) 2 SCl 2 Pb 各種鉛化合物の溶解度積 数値が大きいほど溶解し難い

27 《重金属類固定化メカニズム》 ( 六価クロム固定化メカニズム) クロムの酸化・還元反応による価数の変化 Cr 2 O 7 2 - + 14H + + 6 e - 2 Cr 3 + + 7 H 2 O 焼却過程で安定な三価クロムが酸化反応により六価クロムとなり、 硫化薬剤の還元作用により再び三価クロムへ変化することで安定化する。 還元反応 酸化反応

28 重金属安定化メカニズム:p H 強アルカリ性及びフリーデル氏塩生成によ る重金属安定化 強アルカリ性となり、水酸化物あるいは 低溶解度度化合物を生成する PbCl 2 + Ca(OH) 2 → Pb(OH) + CaCl 2 2Na 2 AsO 4 + 3Ca(OH) 2 → Ca 3 (AsO 4 ) 2 + 6NaOH

29 混合することで生じる化学式 Pb , As の安定化 PbCl 2 + Ca(OH) 2 → Pb(OH) 2 + CaCl 2 2Na 3 AsO 4 + 3Ca(OH) 2 → Ca 3 (AsO 4 ) 2 + 6NaOH Pb ( 鉛 ) As ( ヒ素 ) 水酸化物 低溶解度化合物


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