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REINFORCEMENT EFFECT EVALUATION FOR THE GEOSYNTHETICE CLAY BANKING

題目. REINFORCEMENT EFFECT EVALUATION FOR THE GEOSYNTHETICE CLAY BANKING. K. TSUJI. NAGASAKI UNIVERSITY. Y.TANABASHI. Y.JIANG. Technology. Development of urban and underground space. Security of the right spot is the difficult Increase of the cost.

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REINFORCEMENT EFFECT EVALUATION FOR THE GEOSYNTHETICE CLAY BANKING

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  1. 題目 REINFORCEMENT EFFECT EVALUATION FOR THE GEOSYNTHETICE CLAY BANKING K. TSUJI NAGASAKI UNIVERSITY Y.TANABASHI Y.JIANG

  2. Technology. Development of urban and underground space • Security of the right spot is the difficult • Increase of the cost Low quality soft clay from construction Background of study① Society ＆ environment The reuse of low quality soil is promoted. Geosynetics reinforcement

  3. The design of geocomposite is in a study phase. Development of geocomposite. • Drainage capability Background of study ② + • Tension strength The geocomposite is feasible and more economic.

  4. The reinforcement effect of geocomposite is evaluated by finite difference analysis. Behavior prediction Suggestion for the design of geocomposite reinforced embankment Purpose of the study. Kanto loam (The low quality soil) ・ Change of the consolidation of the every layer of the banking. The steep slope is assumed. ・Reinforcement function of geoconposite.

  5. The membrane element is selected to simulate. The behavior of the banking was evaluated. Analysis method and outline. The difference between the construction period. Set at each layer. Mohr-Coulomb model • Strength constant of the soil. • Friction angle of GC-soil.

  6. The difference between construction period and drainage distance by the laying interval. • Strength constant of the soil. • Friction angle of GC-soil Analysis case.

  7. Physical properti values of banking material(Kanto lome) Item Parameter Volumetric elastic coefficient bulk modulus K(kPa) 500 Cohesion c (kPa) 19.6 Densityρ (g/cm3) 1.363 Angel of internal frictionφcu(deg) Expression (1) Dilatancy angularψ(deg) 0 Limit of tensile stressσ’ (kPa) 1.96 Physical properties value of geocomposite Cohesion of interface (kPa) 4.41 Calculated from direct shear test. Angel of internal friction of interfaceφcus(deg) Expression (2) Rotation of elastic modulus (kPa) 280000 The physical property in analysis.

  8. （1） Consolidation time (min) （2） ：kanto lome ：The friction angle of GC-soil interface Choesion：It is almost constant regardless of the progress of the consolidation. Angle of internal friction：After the primary consolidation end, it approaches in the constant value. Result of direct shear test. ccu=19.6 (kPa) Kanto lome ccus= 4.41 (kPa) The friction angle of GC-soil interface Choesion：It is almost constant regardless of the progress of the consolidation. Angle of internal friction：After the primary consolidation end, it approaches in the constant value.

  9. In this study Different consolidation coefficient and consolidation period were set at every 90cm/layer Determination of the physical property. Banking consolidation period Introduction of banking consolidation period. From layer ①, the subsequent layers were heaped step by step, and actual consolidation period for every layer was calculated. ⑥ ⑤ ④ ③ ② ① 〔 Reference literature. 〕Y.Tnahashi and H.Nagashima (2002): Geocomposite design method tentative plan.

  10. Consideration of construction period. The consolidation period for each layer is assumed to be the same, as illustrated ⑥ ⑤ Erea ④ Banking height ③ The construction process. ② （m） ① Construction period Time

  11. Crown width B=2H Banking height H (m) ：The membrane element The analytical model A footing loading is loaded at every 5-10 kPa step to the crown surface of the embankment

  12. Displaced linearly. The control of settlement. GC45_10day N_10day GC45_30day N_30day GC90_10day Increases with the consolidation degree GC90_30day Loading –settlement curve (8m) Strength of load (kPa) Settlement (m) A limit in the strengthning

  13. Displaced linearly The control of settlement. GC45_20day The rapid settlement. GC45_30day 12m seem to be the limit GC90_30日day GC90_20day N_30日 N_20日 The effect of consolidation period is not remarkable Loading –settlement curve (12m) Strength of load (kPa) Settlement (m)

  14. The limit of embankment height is 14.4ｍ A height of11.3m Evaluation of limit of banking height. Limit of embankment height Safety factor Banking height (m)

  15. The difference between the settlement. The settlement of the higher embankment is large The crown settlements of different height cases with GC45cm Strength of load (kPa) Settlement (m) H=8m_GC45_30 day H=12m_GC45_30 day H=16m_GC45_40 day

  16. No large deformation GC90_50kPa The embankment is stable. GC45_50kPa A large deformation occurred under a surface load of 50kPa The embankment collapses N_50kPa 100ｃｍ Load strength-deformation slope (8m) Initial slope

  17. GC90_50kPa Deformation strength is small Deformation is restrained GC45_50kPa Load strength-deformation slope (12m) 100ｃｍ Initial slope

  18. 55kPa 50kPa 10kPa 20kPa 40kPa 30kPa ： Destruction The destruction area develops. The embankment collapses Shear failure region (N) Load strength Case N 8m

  19. 30kPa 55kPa 50kPa 20kPa 10kPa 40kPa The displacement is large. The destruction area Displacement vector(N) 10kPa Load strength Case N 8m

  20. 40kPa 20kPa The embankment is stable. Displacement control. 60kPa Displacement vector ( GC45cm) 10kPa Load strength Case GC45 8m

  21. 60kPa 10kPa 20kPa ： 80kPa 40kPa No progress of breakdown region to banking upper part. The embankment is stable. Shear failure region ( GC45cm) Load strength Destruction ケースGC45 8m

  22. The embankment is stable. Tensile stress of the reinforcement material The dispersion of the stress. Geocomposite tensile stress (kPa) The stress is also concentrating each GC near 4～6m from the slope The effect of the stress concentration on the toe slope. The displacement control by the reinforcement maternal. Distance from slope (m) Tensile stress the reinforcement material Geocomposite tensile stress (kPa) Distance from slope (m)

  23. Conclusion The strengthening by consolidation. • Considering the construction period. • Loading –settlement curve,Deformation of slope & Displacement vector. The effect of restraining the displacement of the slope. Design of geocomposite reinforced embankment. • Tensile stress of the reinforcement material

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