カテゴリー Ⅱ 日本建築学会構造系論文集第 80 巻第 713 号, ,2015 年 7 月 J. Struct. Constr. Eng., AIJ, Vol. 80 No. 713, , Jul., 2015 鉛直交番荷重を受ける羽根付杭の杭径および羽根径が鉛直

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1 カテゴリー Ⅱ 日本建築学会構造系論文集第 80 巻第 713 号, ,2015 年 7 月 J. Struct. Constr. Eng., AIJ, Vol. 80 No. 713, , Jul., 2015 鉛直交番荷重を受ける羽根付杭の杭径および羽根径が鉛直支持力 引抜き抵抗力に与える影響 EFFECTS OF SHAFT AND WING DIAMETERS OF A WING PILE ON BEARING CAPACITY AND PULL-OUT RESISTANCE UNDER ALTERNATELY CYCLIC VERTICAL LOADING 卜部光平 *, 時松孝次 **, 鈴木比呂子 *** ****, 浅香美治 Kohei URABE, Kohji TOKIMATSU, Hiroko SUZUKI and Yoshiharu ASAKA To investigate effects of the shaft and wing diameters of single wing pile on bearing capacity and pull-out resistance under alternately cyclic vertical loading, monotonic and cyclic vertical loading tests were conducted on a straight and wing piles having different shaft and wing diameters in sand under centrifugal acceleration of 30G. The results show that before the shaft friction reaches the ultimate value during cyclic vertical loading, the pile tip resistance and the shaft friction are the main components resisting the vertical load, so that the effects of the shaft diameter is dominant in the pushing direction and the effects of the shaft diameter and wing ratio (the ratio of wing diameter to shaft diameter) are dominant in the pulling direction. Thereafter, the pile tip resistance and the wing resistance are the main components resisting the vertical load, so that the effects of the shaft and wing diameters are dominant in the pushing direction and the effects of the wing ratio and the wing area are dominant in the pulling direction. Keywords : Wing pile, Alternately cyclic vertical loading, Bearing capacity, Pull-out resistance, Centrifugal model tests, Sand 1. 1) 2) Tsuha 3) Jardine 4) 5) 6) * ** *** **** 東京工業大学大学院理工学研究科建築学専攻大学院生東京工業大学大学院理工学研究科建築学専攻教授 工博千葉工業大学工学部建築都市環境学科准教授 博士 ( 工学 ) 清水建設 技術研究所主任研究員 博士 ( 工学 ) Grad. Stud., Dept. of Architecture and Building Engineering, Tokyo Institute of Technology Prof., Dept. of Architecture and Building Engineering, Tokyo Institute of Technology, Dr. Eng. Assoc. Prof., Dept. of Architecture and Civil Engineering, Chiba Institute of Technology, Dr. Eng. Senior Research Engineer, Institute of Technology, Shimizu Corporation, Dr. Eng. 1113

2 7) 8) 9)10) ~ 11) 1.5 1)~ 3) Fig.1 Test model 2. Fig.1 500mm 500mm 400mm 250mm Dr=90% 160mm 10mm 240mm Dr Dr=90~96% Fig.2 Table1 1 Fig.2(a) D Dw 4 Fig.2(b)~(e) Fig.3 D Dw/D SS304 W Table1 Sizes of pile models (a) 2S (b) 2W1.5 (c) 2W2.0 (d) 1W2.1 (e) 3W1.4 Fig.2 Pile models Fig.3 ID of pile models 1114

3 Table2 Test cases 1.09mm 2.17mm 3.26mm 3 Cyc 4 2S 2W1.5 2W2.0 D=21.7mm 1% 5% 10% 15% Fig Fig.2 ~ 2 Fig.5 Q Rp Rf Q Fig.2 Rw Rp Q (1)~(4) : Qc = Rp + Rfc (1) : Qt = Rft (2) : Qc = Rp + Rfc + Rwc (3) : Qt = Rft + Rwt (4) c t Sc St s Cyc c (a) Case Sc, St (b) Case Cyc Fig.5 Forces acting Fig.4 Images of loading history on wing pile 3.0mm Fig.2 Table2 30G 1.0mm/min Sc St Cyc Fig.4 Fig.4(a) Sc +0.52D~2.1D St -0.23D~1.0D Cyc Fig.4(b) mm 3. Fig.6 Sc Qc Rp Rfc Rwc Qc Fig.6(a) Dw 2S D Rp Fig.6(b) Qc D Rfc Fig.6(c) 7D~15D Qc Rp +30~80mm D 6~12% Rwc Fig.6(d) Rp +60mm +60mm Aw Table1 Fig.6 Relations of pile head displacement with pile head axial force Q c, pile tip resistance R p, shaft friction R fc, wing resistance R wc in monotonic compressive loading tests 1115

4 Fig.7 Relations of pile head displacement with pile head axial force Q t, shaft friction R ft, wing resistance R wt in monotonic tensile loading tests Fig.8 Relations of pile head displacement with shaft friction of each depth R fi in monotonic compressive and tensile loading tests Fig.7 St Qt Rft Rwt Qt Fig.7(a) -50~200mm Rft Fig.7(b) -50~100mm D 10~13% 2W2.0 2S 2W1.5 Dw/D 2W2.0 Rwt Fig.7(c) Fig.6(d) -100~200mm Rft -50~100mm Rfi Fig.8 Sc St Rfi 2S St 2W1.5 2W2.0 Fig.8(a)(b)(c) 0~0.9m 0.9~1.8m Rfi Rfi 30~100mm D 3~20% Dw/D 2W2.0 Fig.8(c) 1W2.1 Fig.8(d) 30~100mm 1) 5~20mm 12) 20mm 20~70mm Fig.9 Cyc Rp Fig.9 Relations of pile head displacement with pile tip resistance R p 1116

5 Fig.10 Relations of loading step with c R p Fig.11 Relations of loading step with normalized force c R p / s R p Sc St Rp Sc Fig.10 Cyc crp crp 65mm 11) D crp Cyc Rp Sc Fig.11 crp srp crp/srp D 100mm mm crp/srp Fig.12 Cyc Rf Rf D Dw 30mm Sc St Fig Cyc crfc crft crfc crft 30mm crfc crft 13) Fig.12 Relations of pile head displacement with shaft friction R f Fig.13 Relations of loading step with c R fc Fig.14 Relations of loading step with c R ft 1117

6 Fig.15 Relations of loading step with normalized force c R fc / s R fc Fig.16 Relations of loading step with normalized force c R ft / s R ft Fig.17 Relations of pile head cumulative displacement with shaft friction R f Fig.13 Dw/D 2.0 crfc 65mm crft Dw/D 2.0 Dw/D crfc crft Sc St Fig crfc crft Sc St srfc srft crfc/srfc crft/srft D Dw Fig Dw/D crfc/srfc 100mm 0.5 crft/srft 100mm 0.2 Fig.12 Rf Sc St 30~100mm D 6~13% Cyc 30mm D 3~6% Fig.17 Rf Rf Sc St 14) 11) 4.3 Fig.18 Cyc Rw Rwc Rp Rwt 30mm Fig Cyc 1118

7 Fig.18 Relations of pile head displacement with wing resistance R w Fig.19 Relations of loading step with c R wc Fig.20 Relations of loading step with c R wt Fig.21 Relations of loading step with normalized force c R wc / s R wc Fig.22 Relations of loading step with normalized force c R wt / s R wt crwc crwt Fig.19 crwc 30mm crwt Fig.20 30mm D Rw Fig.2 D Rw 65mm Rwt Fig.20 crwt Dw/D mm Dw/D 2.0 Dw/D crwc crwt Sc St Fig crwc crwt Sc St srwc srwt Fig.21 crwc/srwc D Dw 100mm 1.1 Fig.22 crwt/srwt 65mm Dw/D mm 0.3 Dw/D 2.0 crwt/srwt 100mm 0.3~0.7 Aw 1 crwt Aw Dw/D 1119

8 Fig.23 Relations of pile head displacement with pile head axial force Q Fig.24 Relations of loading step with c Q c and c Q t Aw 4.4 Fig.23 Cyc Q Qc Sc Qt 30mm Q Fig.24 Cyc cqc cqt crp crfc crft crwc crwt Fig.24(a)~(e) crp crfc 30mm D crwc cqc 30mm D crfc 30mm 65mm crp crwc cqc 65mm D Dw Fig.24(f)~(j) crft 30mm D crwt crft Dw/D 2W2.0 1W2.1 cqt 30mm D Dw/D crft 30mm 65mm crwt 2W2.0 Fig.24(g)(i)(j) cqt crwt 100mm 2W2.0 Fig.24(h) crwt 100mm cqt cqt 65mm cqc cqt Fig cqc cqt Sc St sqc sqt Fig.25 cqc/sqc D Dw 100mm 1.6 Fig.26 cqt/sqt 2W2.0 30mm 100mm 2W1.5 3W S 1W ~0.3 Dw/D Aw 2W2.0 cqt/sqt 100mm

9 Fig.25 Relations of loading step with normalized force c Q c / s Q c Fig.26 Relations of loading step with normalized force c Q t / s Q t Dw/D Aw 5. 1) 2) / 3) 6~13% 4) ±100mm 10~20% 5 2 5) ) : ) ) C.H.C. Tsuha, P.Y. Foray, R.J. Jardine, Z.X. Yang, M. Silva, S. Rimoy : Behaviour of displacement piles in sand under cyclic axial loading, Soils and Foundations, Vol.52, No.3, pp , ) R.J. Jardine, J.R. Standing : Field axial cyclic loading experiments on piles driven in sand, Soils and Foundations, Vol.52, No.4, pp , ) : NS Vol.41 No.2 pp ) : No.601 pp ) : No.651 pp ) : 45 pp ) : 0 B-1 pp ) : B-1 pp ) : Vol.77 No.681 pp ) : B-1 pp ) : B pp ) : B pp ) : 48 pp ) : B-1 pp ) : 49 pp

10 EFFECTS OF SHAFT AND WING DIAMETERS OF A WING PILE ON BEARING CAPACITY AND PULL-OUT RESISTANCE UNDER ALTERNATELY CYCLIC VERTICAL LOADING Kohei URABE *, Kohji TOKIMATSU **, Hiroko SUZUKI *** and Yoshiharu ASAKA **** * Grad. Stud., Dept. of Architecture and Building Engineering, Tokyo Institute of Technology ** Prof., Dept. of Architecture and Building Engineering, Tokyo Institute of Technology, Dr. Eng. *** Assoc. Prof., Dept. of Architecture and Civil Engineering, Chiba Institute of Technology, Dr. Eng. **** Senior Research Engineer, Institute of Technology, Shimizu Corporation, Dr. Eng. Piles supporting structures suffer cyclic vertical loading due to the overturning moment from the structure. In the case of tower-like structures, the vertical load induced by the overturning moment can be large. Cyclic vertical loading reduces frictional resistance of piles, which also affects the bearing capacity and pull-out resistance. This decrease in frictional resistance could cause permanent tilt of a structure. However, the specific mechanism causing this phenomenon has not been thoroughly examined. This study investigates the effects of shaft and wing diameters of a wing pile (a pile with a wing plate near the pile tip) on bearing capacity and pull-out resistance under cyclic vertical loading. Monotonic and cyclic vertical loading tests were conducted on straight and wing piles having different shaft diameters (D) and wing diameters (Dw). Pile models were set in dry Toyoura sand deposit with a relative density of Dr=90~96%. The loading tests were performed with a loading rate of about 1.0mm/min under centrifugal acceleration of 30G. The test results have led to the following conclusions: 1) Before the shaft friction reaches the ultimate value during cyclic loading, the pile tip resistance and the shaft friction are the main components resisting the compression load, so that the effects of the shaft diameter is dominant. Thereafter, the pile tip and wing are the main components resisting the compression load, so that the effects of the shaft and wing diameters are dominant. 2) Before the shaft friction reaches the ultimate value during cyclic loading, the shaft friction is the main component resisting the tension load, so that the effects of the shaft diameter and the wing ratio are dominant. Thereafter, the wing is the main component resisting the tension load, so that the effects of the wing ratio and the wing area are dominant. 3) The shaft friction in monotonic loading reaches the ultimate value and then decreases when the pile displacement exceeded the yield displacement (about 6~13% of shaft diameter). In cyclic vertical loading, the shaft friction decreases when the cumulative pile displacement exceeds the yield displacement, where the cumulative pile displacement is the positive amount of pile displacement in both pushing and pulling directions. 4) Regardless of whether the pile has a wing or not and of the wing ratio (Dw/D), the shaft friction after reaching the ultimate value in cyclic loading is reduced to about 50% in the pushing direction and about 20% in the pulling direction with respect to that in monotonic loading. 5) Wing piles have high compression and tension resistances, the latter of which is about wing ratio (Dw/D) times that of a straight pile with the same shaft diameter. The tensile resistance of wing piles with a wing ratio of about 1.5 decreases significantly with increasing cyclic vertical displacement after the shaft friction reaches its ultimate value, but that of wing piles with a wing ratio of about 2.0 does not decrease significantly. (2015 年 2 月 10 日原稿受理,2015 年 4 月 6 日採用決定 ) 1122