Effect of sand liquefaction on mechanical properties of pile foundation under strong earthquake
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摘要: 为了提高位于液化土层桥梁桩基的抗震性能, 基于三向六自由度大型振动台模型试验, 分析了地震波作用下桩顶水平位移、桩身加速度及弯矩等动力响应, 并研究了地震波加载后桩基的损伤。试验结果表明: 在地震波作用下, 随着液化层埋深的增加, 土体液化后产生的侧扩效果逐渐减弱, 因此, 桩顶水平位移峰值逐渐减小, 但是当地震加速度超过0.6g时, 桩顶水平位移峰值不受液化层埋深的影响; 因地震荷载作用下粉细砂土层液化, 桩身加速度在该土层位置明显增大; 上部覆盖层压力作用使土层抗剪强度增大, 因此, 桩顶放大系数随着液化层深度的增加而增大, 且桩顶放大系数在Kobe波作用下最大, 5002波作用下最小, 砂土液化同时造成土层强度降低, 从而使桩身加速度在该土层出现放大效应; 桩身弯矩最大值均出现在液化层和非液化层分界处, 且在相同强度地震波作用下, 桩身弯矩最大值随着液化层埋深的增加呈增大趋势, 当地震加速度从0.30g增大到0.35g后, 桩身弯矩增幅为33.3%, 增幅最大; 不同类型地震波对桩基的破坏程度并无差异, 在加速度0.35g作用下, 桩基基频无变化, 但当地震波强度超过0.40g时, 桩基基频从1.65 Hz突降到0.45 Hz, 因砂土层液化产生侧向位移, 桩身剪切变形, 最终导致桩基损坏。综上所述, 当液化层较浅时, 应重点考虑地震波作用下过大的桩顶水平位移; 在桩基抗震设计时, 必须考虑液化层和非液化层分界处桩基的抗弯能力和液化层埋深的影响。Abstract: In order to improve the seismic resistance behavior of bridge pile foundation located at the liquefied layer, the shaking table model test with three directions and six degrees of freedom was carried out, the dynamic responses of pile tops' horizontal displacements and piles' accelerations and bending moments were analyzed under the seismic waves, and the damages of pile foundations under the actions of seismic waves were studied. Experiment result shows that, under the actions of seismic waves, the lateral expansion effect gradually decreases with the increase of the depth of liquified layer. Therefore, the peak horizontal displacement of pile top gradually decreases. However, the peak horizontal displacement of pile top will no longer be affected by the liquefied layer depth when the seismic acceleration exceeds 0.6g. The pile accelerations increase significantly in the fine sand layer because of the liquefaction of fine sand layer under the seismic loads. The stress caused by the overburden soil can enhance the shear strength of lower layer, therefore, the amplification factor of pile top increases as the depth of liquefied layer increases. Moreover, the amplification factor is the largest under the action of Kobe wave, and the smallest under the action of 5002 wave. The sand liquefaction also causes the strength of soil layer to decrease, leading to the acceleration magnification in the soil layer. All the maximum bending moments of piles appear at the boundary between the liquefied layer and non-liquefied layer, and under the same seismic intensity, the maximum bending moment of pile increases with the increase of liquefaction layer depth. When the seismic acceleration increases from 0.30g to 0.35g, the bending moment of pile shows a maximum increase of 33.3%. The pile foundations experience no difference in the damages caused by different types of seismic waves. Under the acceleration of 0.35g, the fundamental frequency of pile foundation has no change. But when the seismic wave strength exceeds 0.40g, the fundamental frequency of pile foundation suddenly drops from 1.65 Hz to 0.45 Hz. The pile foundations in the sand layer laterally displace due to the liquefaction, and the piles deform due to the shear stress, eventually leading to the damages of pile foundations. In conclusion, when the liquefied layer is relatively shallow, the excessive horizontal displacements of pile tops under the actions of seismic waves should be fully considered. In the seismic design of pile foundation, the bending resistance of pile foundation at the boundary between the liquefied and non-liquefied layer, and the liquefied layer depth must be considered.
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图 7 5010波作用下桩顶水平位移
Figure 7. Horizontal displacements of pile tops under 5010 wave action
图 8 EL-Centro波作用下桩顶水平位移
Figure 8. Horizontal displacements of pile tops under EL-Centro wave action
图 11 不同地震波作用下桩顶加速度放大系数比较
Figure 11. Comparison of amplification factors of pile top accelerations under different seismic wave actions
图 13 EI-Centro波作用下桩身加速度峰值
Figure 13. Peak accelerations of piles under EL-Centro wave action
图 14 不同地震波强度下桩顶加速度放大系数比较
Figure 14. Comparison of acceleration factors of pile tops under different seismic wave intensities
图 15 不同地震波作用下桩身弯矩
Figure 15. Bending moments of piles under different seismic wave actions
图 16 不同地震波作用下桩身弯矩最大值比较
Figure 16. Comparison of maximum bending moments of piles under different seismic wave actions
图 18 EL-Centro地震波作用下桩身弯矩
Figure 18. Bending moments of piles under EL seismic wave action
图 20 地震波型对桩基基频的影响
Figure 20. Influence of seismic waves on pile fundamental frequencies
图 21 地震波强度对桩基基频的影响
Figure 21. Influence of seismic wave intensities on pile fundamental frequencies
表 1 桩基测试元件布设位置
Table 1. Test elements setting positions of pile foundations
测试元件类型 应变片 加速度计 位移计 布设位置/cm 10、50、75、115、134 0、10、50、75、115、134 0 测试元件总数 30 18 3 
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表 2 试验工况
Table 2. Test conditions
地震波类型 地震波强度/g 白噪声 0.05 5010波 0.15、0.20、0.25、0.30、0.35 5002波 0.35 Kobe波 0.35 EL-Centro波 0.35、0.40、0.45、0.50、0.55、0.60、0.80
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[1] RAHMANI A, PAK A. Dynamic behavior of pile foundations under cyclic loading in liquefiable soils[J]. Computers and Geotechnics, 2012, 40: 114-126. doi: 10.1016/j.compgeo.2011.09.002 [2] CHUNG Y, NAGAE T, HITAKA T, et al. Seismic resistance capacity of high-rise buildings subjected to long-period ground motions: e-defense shaking table test[J]. Journal of Structural Engineering, 2010, 136 (6): 637-644. doi: 10.1061/(ASCE)ST.1943-541X.0000161 [3] 凌贤长. E-Defense建设与相关研究[J]. 地震工程与工程振动, 2008, 28 (4): 111-116. https://www.cnki.com.cn/Article/CJFDTOTAL-DGGC200804016.htmLING Xian-zhang. E-defense and research tests[J]. Journal of Earthquake Engineering and Engineering Vibration, 2008, 28 (4): 111-116. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-DGGC200804016.htm [4] CHAU K T, SHEN C Y, GUO X. Nonlinear seismic soil-pile-structure interactions: shaking table tests and FEM analyses[J]. Soil Dynamics and Earthquake Engineering, 2009, 29 (2): 300-310. doi: 10.1016/j.soildyn.2008.02.004 [5] DASH S R, BHATTACHARYA S, BLAKEBOROUGH A. Bending-buckling interaction as a failure mechanism of piles in liquefiable soils[J]. Soil Dynamics and Earthquake Engineering, 2010, 30 (1/2): 32-39. [6] 王青桥, 韦晓, 王君杰, 等. 桥梁桩基震害特点及其破坏机理[J]. 震灾防御技术, 2009, 4 (2): 167-173. doi: 10.3969/j.issn.1673-5722.2009.02.005WANG Qing-qiao, WEI Xiao, WANG Jun-jie, et al. Characteristics and mechanisms of earthquake damage of bridge pile foundation[J]. Technology for Earthquake Disaster Prevention, 2009, 4 (2): 167-173. (in Chinese). doi: 10.3969/j.issn.1673-5722.2009.02.005 [7] 唐亮, 凌贤长, 徐鹏举, 等. 可液化场地桥梁群桩基础地震响应振动台试验研究[J]. 岩土工程学报, 2010, 32 (5): 672-680. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201005006.htmTANG Liang, LING Xian-zhang, XU Peng-ju. Shaking table test on seismic response of pile groups of bridges in liquefiable ground[J]. Chinese Journal of Geotechnical Engineering, 2010, 32 (5): 672-680. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201005006.htm [8] 凌贤长, 王东升, 王志强, 等. 液化场地桩-土-桥梁结构动力相互作用大型振动台模型试验研究[J]. 土木工程学报, 2004, 37 (11): 67-72. doi: 10.3321/j.issn:1000-131X.2004.11.011LING Xian-zhang, WANG Dong-sheng, WANG Zhi-qiang, et al. Large-scale saking table model test of dynamic soil-pile-bridge structure interaction in ground of liquefaction[J]. China Civil Engineering Journal, 2004, 37 (11): 67-72. (in Chinese). doi: 10.3321/j.issn:1000-131X.2004.11.011 [9] 李培振, 程磊, 吕西林, 等. 可液化土-高层结构地震相互作用振动台试验[J]. 同济大学学报(自然科学版), 2010, 38 (4): 467-474. doi: 10.3969/j.issn.0253-374x.2010.04.001LI Pei-zhen, CHENG Lei, LYU Xi-lin, et al. Shaking table testing on high-rise buildings considering liquefiable soil-structure interaction[J]. Journal of Tongji University (Natural Science), 2010, 38 (4): 467-474. (in Chinese). doi: 10.3969/j.issn.0253-374x.2010.04.001 [10] LIYANAPATHIRANA D S, POULOS H G. Seismic lateral response of piles in liquefying soil[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2005, 131 (12): 1466-1479. doi: 10.1061/(ASCE)1090-0241(2005)131:12(1466) [11] 王睿, 张建民, 张嘎. 液化地基侧向流动引起的桩基础破坏分析[J]. 岩土力学, 2011, 32 (增1): 501-506. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX2011S1090.htmWANG Rui, ZHANG Jian-min, ZHANG Ga. Analysis of failure of piled foundation due to lateral spreading in liquefied soils[J]. Rock and Soil Mechanics, 2011, 32 (S1): 501-506. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX2011S1090.htm [12] SU Lei, TANG Liang, LING Xian-zhang, et al. Pile response to liquefaction-induced lateral spreading: a shake-table investigation[J]. Soil Dynamics and Earthquake Engineering, 2016, 82: 196-204. doi: 10.1016/j.soildyn.2015.12.013 [13] 黄占芳, 白晓红. 可液化砂土中群桩基础地震响应的振动台试验研究[J]. 振动与冲击, 2013, 32 (18): 153-158. doi: 10.3969/j.issn.1000-3835.2013.18.029HUANG Zhan-fang, BAI Xiao-hong. Shaking table model test for seismic response of a pile group foundation with liquefiable sandy soil[J]. Journal of Vibration and Shock. 2013, 32 (18): 153-158. (in Chinese). doi: 10.3969/j.issn.1000-3835.2013.18.029 [14] 夏修身, 李建中. 近场地震动对桩基础高墩摇摆反应的影响[J]. 哈尔滨工业大学学报, 2014, 46 (4): 82-86. https://www.cnki.com.cn/Article/CJFDTOTAL-HEBX201404014.htmXIA Xiu-shen, LI Jian-zhong. Effect of near-field ground motion on the rocking response of tall pier with pile foundations[J]. Journal of Harbin Institute of Technology, 2014, 46 (4): 82-86. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-HEBX201404014.htm [15] 张泽涵, 钱德玲, 戴启权, 等. 液化地基上超高层结构模型振动台试验研究[J]. 建筑结构学报, 2016, 37 (7): 114-120. https://www.cnki.com.cn/Article/CJFDTOTAL-JZJB201607014.htmZHANG Ze-han, QIAN De-ling, DAI Qi-quan, et al. Shaking table test of super high-rise structure on liquefied ground[J]. Journal of Building Structures, 2016, 37 (7): 114-120. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-JZJB201607014.htm [16] 戴启权, 钱德玲, 张泽涵, 等. 液化场地超高层建筑群桩基础动力响应试验研究[J]. 岩石力学与工程学报, 2015, 34 (12): 2572-2579. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201512021.htmDAI Qi-quan, QIAN De-ling, ZHANG Ze-han, et al. Experimental research on dynamic response of pile group of super highrise building on liquefied ground[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34 (12): 2572-2579. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201512021.htm [17] 孔锦秀. 地震动特性对液化场地桥梁桩基础动力反应的影响[D]. 哈尔滨: 哈尔滨工业大学, 2016.KONG Jin-xiu. Effects of ground motion characteristics on dynamic response of bridge pile foundations in liquefiable soils[D]. Harbin: Harbin Institute of Technology, 2016. (in Chinese). [18] 张效禹, 唐亮, 凌贤长, 等. 液化场地桥梁桩-土动力相互作用p-y曲线特性研究[J]. 防灾减灾工程学报, 2014, 34 (5): 619-625. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXK201405014.htmZHANG Xiao-yu, TANG Liang, LING Xian-zhang, et al. Analysis on characteristics of dynamic p-y curves for soil-pile interaction in liquefiable ground[J]. Journal of Disaster Prevention and Mitigation Engineering, 2014, 34 (5): 619-625. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-DZXK201405014.htm [19] 冯忠居, 谢永利. 大直径钻埋预应力混凝土空心桩承载力的试验[J]. 长安大学学报(自然科学版), 2005, 25 (2): 50-54. doi: 10.3321/j.issn:1671-8879.2005.02.012FENG Zhong-ju, XIE Yong-1i. Simulation test of large diameter bored hollow pile of prestressing force concrete[J]. Journal of Chang'an University (Natural Science Edition), 2005, 25 (2): 50-54. (in Chinese). doi: 10.3321/j.issn:1671-8879.2005.02.012 [20] 冯忠居, 任文峰, 李晋. 后压浆技术对桩基承载力的影响[J]. 长安大学学报(自然科学版), 2006, 26 (3): 35-38. https://www.cnki.com.cn/Article/CJFDTOTAL-XAGL200603008.htmFENG Zhong-ju, REN Wen-feng, LI Jin. Bearing capacity of post grouting pile foundation[J]. Journal of Chang'an University (Natural Science Edition), 2006, 26 (3): 35-38. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-XAGL200603008.htm [21] 李晋, 冯忠居, 谢永利. 大直径空心桩承载性状的数值仿真[J]. 长安大学学报(自然科学版), 2004, 24 (4): 36-39. https://www.cnki.com.cn/Article/CJFDTOTAL-XAGL200404009.htmLI Jin, FENG Zhong-ju, XIE Yong-li. Numerical simulation of large diameter hollow pile bearing performance[J]. Journal of Chang'an University (Natural Science Edition), 2004, 24 (4): 36-39. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-XAGL200404009.htm [22] 劳伟康, 周立运, 王钊. 大直径柔性钢管嵌岩桩水平承载力试验与理论分析[J]. 岩石力学与工程学报, 2004, 23 (10): 1770-1777. doi: 10.3321/j.issn:1000-6915.2004.10.033LAO Wei-kang, ZHOU Li-yun, WANG Zhao. Field test and theoretical analysis on flexible large-diameter rock-socketed steel pipe piles under lateral load[J]. Chinese Journal of Rock Mechanics and Engineering, 2004, 23 (10): 1770-1777. (in Chinese). doi: 10.3321/j.issn:1000-6915.2004.10.033 [23] 冯士伦, 王建华. 饱和砂土中桩基的振动台试验[J]. 天津大学学报, 2006, 39 (8): 951-956. https://www.cnki.com.cn/Article/CJFDTOTAL-TJDX200608012.htmFENG Shi-lun, WANG Jian-hua. Shake table test on pile foundation in saturated sand[J]. Journal of Tianjin University, 2006, 39 (8): 951-956. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-TJDX200608012.htm [24] 王建华, 冯士伦. 桩土相互作用的振动台试验研究[J]. 岩土工程学报, 2004, 26 (5): 616-618. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC200405007.htmWANG Jian-hua, FENG Shi-lun. The shake table test on soil-pile interaction[J]. Chinese Journal of Geotechnical Engineering, 2004, 26 (5): 616-618. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC200405007.htm [25] 张鑫磊, 王志华, 许振巍, 等. 液化砂土流动效应的振动台试验研究[J]. 岩土力学, 2016, 37 (8): 2347-2352. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201608029.htmZHANG Xin-lei, WANG Zhi-hua, XU Zhen-wei, et al. Shaking table tests on flow effects of liquefied sands[J]. Rock and Soil Mechanics, 2016, 37 (8): 2347-2352. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201608029.htm [26] JANALIZADEH A, ZAHMATKESH A. Lateral response of pile foundations in liquefiable soils[J]. Journal of Rock Mechanics and Geotechnical Engineering, 2015, 7 (5): 532-539. [27] 冯士伦, 王建华, 郭金童. 液化土层中桩基抗震性能研究[J]. 岩石力学与工程学报, 2005, 24 (8): 1402-1406. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX200508026.htmFENG Shi-lun, WANG Jian-hua, GUO Jin-tong. Seismic resistance of pile foundation in liquefaction layer[J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24 (8): 1402-1406. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX200508026.htm [28] 韦晓, 范立础, 王君杰. 考虑桩-土-桥梁结构相互作用振动台试验研究[J]. 土木工程学报, 2002, 35 (4): 91-97. https://www.cnki.com.cn/Article/CJFDTOTAL-TMGC200204016.htmWEI Xiao, FAN Li-chu, WANG Jun-jie. Shake table test on soil-pile-structure interaction[J]. China Civil Engineering Journal, 2002, 35 (4): 91-97. (in Chinese). https://www.cnki.com.cn/Article/CJFDTOTAL-TMGC200204016.htm [29] 董芸秀, 冯忠居, 郝宇萌, 等. 岩溶区桥梁桩基承载力试验与合理嵌岩深度[J]. 交通运输工程学报, 2018, 18 (6): 27-36. http://transport.chd.edu.cn/article/id/201806004DONG Yun-xiu, FENG Zhong-ju, HAO Yu-meng, et al. Experiment on bearing capacity of bridge pile foundations in karst area sand reasonable rock-socketed depth[J]. Journal of Traffic and Transportation Engineering, 2018, 18 (6): 27-36. (in Chinese). http://transport.chd.edu.cn/article/id/201806004 [30] SOMERVILLE P. Magnitude scaling of the near fault rupture directivity pulse in near-fault ground motions[R]. Pasadena: URS Group, Inc., 2003. [31] TAZARV M. Quantitative identification of near-fault ground motion using Baker's method, an application for March 2011 Japan M9.0 Earthquake[R]. Ottawa: Carleton University, 2011. [32] BAKER J W. Quantitative classification of near-fault ground motions using wavelet analysis[J]. Bulletin of the Seismological Society of America, 2007, 97 (5): 1486-1501. [33] CHAI J F, LIAO W I, TENG T J, et al. Current development of seismic design code to consider the near-fault effect in Taiwan[J]. Earthquake Engineering and Engineering Seismology, 2001, 3 (2): 47-56. -
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