液状化解析技術 - taisei.co.jp

1 37 (2004) 15-1 3 2 Keywords : liquefaction, effective stress analysis , elasto -plastic model, pile foundation, quay wall, underground structure 1. LIQCA DIANA-SD 2. 1) LIQCA DIANA-SD Biot 2) LIQCA ( )3), 4) DIANA-SD Stress-Density Model( )5) ( ) 3 ( ) (NC) (OC) (NC) u (OC) u -1 fb 000000000020 40 60 80 100 120 140 NCfbOC(a)Observed state.

2 NC 000000000020 40 60 80 100 120 140 NCfbOCObserved state: OC(b) -1 Behavior of Oka-Yashima model subjected to cyclic shearing p e Is( -2) ( ) m' m' 15-2 -2 SD Is 5) Definition of State Index Is 3. 6) 40G -3 -3 Schematic view of centrifuge test model Dr=60% ( t=220mm ) Dr=90% (t=100mm ) 2 40cSt ( D= ) 6D (60mm) 2 2 4 40G GL-83m EW ( ) -4 Dr=60 90% 8 LIQCA(3 ) -4 3 3-dimensional finite element model 40G 1) -5 ( u/ v0')

3 -6 37 (2004) s u/ v0' Dr=60 , s u/ v0' Dr=90 ,2-1P -5 Time histories of excess pore pressure ratio in ground -200-150-100-500501001502000 s m/s2 ,2-3A-200-150-100-500501001502000 s m/s2 2-1A -6 Time histories of horizontal acceleration in ground -200-150-100-500501001502000 s m/s2 ,2-3A-6-4-202460 s mm ,S-D -7 Horizontal acceleration and relative displacement of foundation model s 1/m s 1/m -8 Time histories of pile curvature 0 t= t= mm 0 t= t= (a) (b) -9 ( ) Distributions of curvature (when peak value at pile head occurred) 2) -7 3) -8 -9 2 ( -9(a) )

4 0 ( -9(b) ) -10 ( ) Schematic view of test model (steel pile) -10 4m ( ) 3 (D50= ) 4 ( 165mm ) ( 103kg) ( 103kg ) 1/m 15-4 ( 240gal ) -11 2 DIANA-SD(2 ) 8) -11 2 2-dimensional finite element model -12 -13 10 20 -14 -14 2 (A:14 B.

5 43 ) ( -15) A B 010203040500 1020304050 Excess pore waterpressure (kPa)Time (sec) -12 Time histories of excess pore water pressure 0500123456 PWP (kPa) (m) 'v08 10 14 20 42 050 PWP (kPa) 'v08 10 14 20 42 -13 Distributions of excess pore water pressure -20-1001020 0 1020304050 Moment (kNm) ABTime (sec) -14 Time histories of bending moment at pile head -20 -10 0 10 200123456 Moment (kNm) (m) A-20 -10 0 10 20 Moment (kNm) B -15 Distributions of bending moment on pile -20 -10 0 10 200123456 Subgrade reaction (kN/m) (m) -20 -10 0 10 20 Subgrade reaction(kN/m) -16 Distributions of subgrade reaction on pile 37 (2004) 15-5 -16 2 9) ( -14m) 4 5m 2m 4 -17 10) -17 10) Damage of quay wall in 1995 Hyogoken-nanbu earthquake -32m NS ( ) UD ( ) -18 LIQCA(2 )

6 -1 -19 ( 3 ) 1 ( -17 ) -1 Deformation of caisson crest at end of analysis (m) 4 5 (m) 2 ( ) 4 -19 u ratio distribution and deformation at end of analysis -18 2 2-dimensional finite element model 15-64. 3 60kN/m2 11) 15m 25m 50 GL-44m 700mm 12m -20 600mm H 3 - 12) - - - 2 FEM -21 (Case1) (Case2 Case3) Case2 Case3 ( 2) DIANA-SD ( )

7 13) ( ) -22 Case1 Case2 Case3 3 040800 102030405060 (kPa)Time (sec) Case1 Case2 Case3 -22 Time histories of excess pore water pressure -23 1 Case1 Case2 Case3 -24 1 2 My (Case1) 010203005101520 (m) -20 N Change in N-Value with soilimprovement -21 Computation cases (Case2) (Case3) (Case1) 37 (2004) 15-7 My (Case2 Case3) My Case1 Case2 3 -150001500 Case1-150001500 Moment (kNm)Case2-1500015000 102030405060 Time (sec)Case3 -23 Time histories of bending moment at pile head 01000-25-20-15-10-50 Case1 Case2 Case3 Moment (kNm) (m)My 0 1000 2000 Moment (kNm)My -24 Distributions of maximum bending moment 14) ( ) 2 10m 6m 4m 2 RC N 5 13 GL-2m GL-32m NS -25 -6-4-202460 5 10 15 20 Acceleration (m/s2)Time (s)

8 -25 Time history of acceleration of input seismic motion -26 LIQCA(2 ) 1) 2) 3) 4) 4 -26 2 2-dimensional finite element model -27 A B ( u/ v0') -28 ( C) -29 ( 3 ) 5 10 15 20 A B u/ v0'Time (s) -27 Time histories of excess pore water pressure ratio 5 10 15 20 Displacement (m)Time (s) -28 Time history of vertical displacement at top of box culvert -29 u ratio distribution and deformation at end of analysis 5.

9 3 2 2 1) ( ) 1991. 2)Zienkiewicz, and Shiomi,T. : Dynamic behaviour of saturated porous media ; The generalized Biot formulation and its numerical solution, International journal for numerical and analytical methods in geomechanics, , , 1984. 3)Oka,F., Yashima,A., Shibata,T., Kato,M. and Uzuoka,R. : FEM-FDM coupled liquefaction analysis of a porous soil using an elasto -plastic model, Applied Scientific Research, , , 1994.

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