43-60論文-濱田.indd

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1 Study on Lateral Resistance of Piled-Raft Foundations during Earthquake A lot of experimental and analytical studies for piled raft foundations have been conducted to investigate the settlement behavior and the load-sharing between raft and piles for vertical loading. However, there are not sufficient studies on lateral resistance of piled rafts for seismic load. Authors have been carried out the lateral loading tests at large scale, centrifuge model tests, numerical analysis on piled raft foundations and proposed the simple evaluation method and the theoretical equations. This paper shows the achieved results of these studies on piled rafts subjected to lateral loading. Fig.1 Fig FEMFEM 1Chief Researcher, Research & Development Institute, Dr. Eng. 2Senior Chief Researcher, Research & Development Institute 3Research & Development Institute 4Deputy General Manager, Research & Development Institute 43

2 Fig FEM 15 Fig Fig.3Photo 12.5m2.5m8m1m1m0.5m 16 19mm1mmEI0.16kNm 2 76mm2.5mmEI1.24kNm 2 Table m19mms/D13 76mms/D3.3 27mm Table mm0.5mm 6CD d 6042 G 0 c 0.5 1g 1m1m32.3kN/m m20m83.3kN/m kN/m 2 450mm70mmPHCB 1000mm9mm2mm 44

Fig.3 Photo 1 Table 1 mm kn Case 2-4 13 7 32.

2 0 100 Case 1-2 7 12.6 0 100 Case 1-3 7 22.

3 Fig.3 Photo 1 Table 1 mm kn Case mm Case mm Case mm Case mm mm Case Case Case Case Case mm Case mm Case mm Case mm 45

4 Case kN13D32.2kN 21.9kN/m Fig.4 Fig.57mm615B1B4 Fig.6B Fig kN/m 2 Fig.4 Fig.5 Fig.6B Fig.7 Fig.813D Case 2-132kN 21kN/m kNCase mm Fig.8 46

5 Fig.9 3.3D Fig.9 Fig.10 Table kN 77.4kN/m 2 20mm0.4mm485mm 30g0.6m14.55m Case 1Case 2 15mmCase 2 25mm Case 1 60 Fig.11 Fig.122Hz 90 Fig.10Case2 Fig.13Fig.13Fig.14 20Hz0.2Hz Table 2 Case 1 Case 2 g Gal Fig.13b 30 Fig.13d 47

6 竹中技術研究報告 No 論文杭基礎と比較しパイルドラフト基礎の杭曲げモーメントは動的と静的で顕著な差が生じておりこの要因として地盤と建物の位相差 5 が考えられるまた既往の実験同様静的時は動的時よりも杭の水平荷重分担率が大きかった Fig.15に杭頭のせん断力Qと曲げモーメントMの関係杭5本分を示すパイルドラフト基礎のM/Qは動的時の方が静的時より大きく動的時の地中部の最大曲げモーメント発生深度が静的時より深いことと対応している 3.3 考察地盤変形を考慮した梁ばねモデルによる静的非線形弾塑性解析を行い地盤変形の影響を考察する地盤定数は 1 式よりせん断剛性G 2 式中に用いる地盤を求め 2 式より地盤反力係数khを求めたの変形係数E0は試験方法の差から生じる係数 29 の比 8/0.25 を用いて 3 式のように低減しているまた khの非線形性極限地盤反力Py 4 式を考慮しておりパイルドラフト基礎では基礎底 2 面の接地圧 64kN/m による拘束圧の増加を考慮しているここで 3 間隙比e 乾燥密度ρd 1.504kg/cm ポアソン比ν 0.3 内 30 部摩擦角φ 40 を用いている Fig.11 Fig.12 フーリエスペクトル比と位相差 Fig 杭の曲げモーメント分布加速度時刻歴

7 G e e k h 80E 0 B E 0 2lG1/32 3 P y 3K p cmk p Bcm Fig.13Fig.13a,b Fig.14 Fig.13d Fig.14 Fig.15 FEM Fig Fig.16 c 8 Fig.16d Fig.16 Table 3G 0 49

8 c u G 0 400c u Tresca 1.05 Fig.17G/G 0 e K MuDIAN 31 Fig.18 50kN/m m m0.68 Table 3 kn/m c u kpa 50 G 0 kpa EGPa dm 1.0 Lm 20 sm 5.0 m m m Bm 20 Fig.19 Fig.20GL-1m 400kN/m8c 2 u kN/m 2 200kN/m 2 Fig.21 Fig.17G/G 0 e Fig

9 Mindlin Fig.19 G Fig.20GL-1m Fig.22 G h j Fig.21 Fig.22 51

10 M Fig.23 F p F r F r G rp F p hp R hp R hp pp R hp pr gr F r rr R hp pr hp Fig.23 2 k h kn/m 3 5EskN/m 2 B cmes G Fig.23 k h 80EsB 3/4 5 Fig.24 Fig.24 52

11 13D3.3D G Fig.25 FF p F r F p M i M g A r ra r / gf p Fig.26 Fig.25 Fig.26 Cerruti 32 gz z8a 5 9 A 1 A 2 A 3 A F r az gz 2vbe r 1b 6 2Gr EI d 4 z Bkgzz dz 4 h 7 53

12 za 1 e 1iz A 2 e 1iz A 3 e 1iz A 4 e 1iz F r A 5 e 2v1b 2Gr a r z A 5 b 4 4 a 4 9 A 1 A A 3 A 5 2 a 4 i 4 4 a a A 4 A 5 2 a 4 i 4 4 a a gzrvf r G F r ea a r b 2Gr 2vbg0bEIz Bk h 4 Bk h /4EI i1 QM1314Q Top M Top 1516z z06ab Qzab e z a3 2 2 cosz2 2 sinz a 2 e az 4 4 EI 4 4 a 4 13 Mzabe z a3 a 3 2cosz sinz ae az 4 4 EI a Q Top ab a a 2 EI 4 4 a 4 15 a 3 M Top ab 2a EI a 46 nff r F p p F p /F1717 2Gr/2vn4nEI 3 r2 ab 54

13 K p α p F p F K p K r n a r 2Gr n a 2v r 2 a r 3 a b 2 2 r 2 a r 3 a b 2 2 r 3 2 a a 2 r r r n ab 3 2 a a 2 r r r n ab 2Gr 2v a r r 4 4EI 3 4r 4 a 4 EI a r r 4 4EI 3 4r 4 a 4 EI 17 K 18M K M 18 A 3 A 5 2 A 4 A 5 2 a a 1 a i 2 K 4 4 K 2 a a 1 a i 2 K a 4 K 4 2 K 2 1 a 4 K Q Top ab 1 K 2 a K 2 2 a 2 EI a 3 2a2a2 4 4 a 4 15 M Top ab K a a EI K a 4 16 K K EI 50 // Q13 M 14ab 55

14 k h Hardin-DrnevichHD 34 G 0 max Ramberg-OsgoodRO 35 abhd/ max RO/G 0 GRO G 0 G h max 2h max 21 h max 0.5 G/G g Fr /G 0 r 1 a e az 1 e r 1 r G 0 1 2a 2va2 22 az RO22a,b a nl,b nl Fig Fig h max 0.25, 2021 a nl a 1 G G 0 23 b nl 1 1 G 0 1 2va 1 2 G a,ba nl,b nl 22Fig.2829/G 0 Fig.27a nl,b nl /G 0 RO Fig.28/G Fig.29/G

15 Fig Fig Fig.30Fig ba1.49b0.8845k h Es k h 1.3 B 1v 2 12 EsB 4 25 EI FEM

16 2r 1 13B-1pp No.579pp Watanabe,T., Fukuyama,H., Horikoshi,K. and Matsumoto,T: Centrifuge modeling of piled raft foundations subjected to horizontal loads, pp , Proc. 5 th Int. Conf. On Deep Foundation Practice incorporating Piletalk Int B-1pp B-1pp Katzenbach, R. and Turek, J.: Combined pile-raft foundation subjected to lateral loads, Proc. 16 th Int. Conf. On Soil Mechanics and Geotechnical Engineering, pp , pp pp pp Vol.46B pp Vol.48Bpp Pastsakorn, K. and Matsumoto, T.: A simplified analysis method for piled raft foundations in non-homogeneous soils, Int. J. Numer. Anal. Meth. Geomech., pp B-1pp pp FEM43 pp Vol.47Bpp B-1pp pp B-1pp

17 pp B-1pp B-1pp pp pp B-1pp pp pp NC No.54pp pp Hardin,B.O. and Drnevich,V.P.: Shear Modulus and Damping in Soils: Design Equations and CurvesProc. ASCE SM7, pp , Jennings. P.C.: Periodic Response of General Yielding Structure, J.Eng. Mech. Div., ASCE, EM2, pp ,

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