可液化地基单桩基础离心机模型试验的三维数值分析
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摘要
文章通过三维水土耦合动-静一体有限元程序DBLEAVES对饱和砂土地基(Dr=40%)单桩基础的离心机模型试验进行模型试验相对应的原型三维有限元数值模拟和分析。对比分析小震(峰值加速度0.08g)和大震(峰值加速度0.47g)情况下的土体加速度、超静孔隙水压、沉降位移以及桩身弯矩等变化规律。其中,地基土的性质采用应力诱导各向异性的交变移动弹塑性模型模拟,基桩采用弹性梁单元模型模拟。结果表明:①超静孔隙水压会"隔断"振动波的传递,当土体接近完全液化时,土表面峰值加速度会明显小于输入波峰值加速度,而当超静孔隙水压比较小时,土表面加速度相对于输入波则可能会放大;②地震时所达到的最大超静孔隙水压比是地基土沉降量的主要因素之一,且一大部分沉降发生在震后的孔压消散期;③数值模拟与模型试验结果的对比分析表明,交变移动模型可以较好地反映土体在交变荷载下的动力响应特性,验证了所采用的DBLEAVES程序和有限元方法的有效性。
3D soil-water coupled numerical simulation were carried out based on the centrifuge model tests on single-pile foundation in saturated sand(Dr=40%) using the static-dynamic finite element program DBLEAVES.The acceleration response, pore water pressure, displacement and bending moment of pile, the mechanical behaviors of liquefiable sand and pile were examined to analyze the dynamic responses of sand and pile subjected the weak earthquake motion(peak value of acceleration 0.08 g) and strong earthquake motion(peak value of acceleration 0.47 g). Specially, an elasto-plastic cyclic mobility model was used to describe the properties of soil,while the beam element was used to simulate the pile. The simulated results showed that:(1) The excess pore water pressure can ‘bock' the seismic waves. The acceleration of ground surface was significant reduced while the soil was almost liquefied. However, the acceleration could be amplified while the excess pore water pressure was relatively small.(2) The peak value of excess pore water pressure ratio during earthquake is one of the main factors for the settlement of ground surface. Moreover, the main part of settlement occurred during the period of post-earthquake as the excess pore water pressure dissipated.(3) The comparison between the numerical simulation and the model test showed that the used cyclic mobility model could properly describe the seismic behavior of soil. The results also verified the validity of the used program DBLEAVES and FEM method.
3D soil-water coupled numerical simulation were carried out based on the centrifuge model tests on single-pile foundation in saturated sand(Dr=40%) using the static-dynamic finite element program DBLEAVES.The acceleration response, pore water pressure, displacement and bending moment of pile, the mechanical behaviors of liquefiable sand and pile were examined to analyze the dynamic responses of sand and pile subjected the weak earthquake motion(peak value of acceleration 0.08 g) and strong earthquake motion(peak value of acceleration 0.47 g). Specially, an elasto-plastic cyclic mobility model was used to describe the properties of soil,while the beam element was used to simulate the pile. The simulated results showed that:(1) The excess pore water pressure can ‘bock' the seismic waves. The acceleration of ground surface was significant reduced while the soil was almost liquefied. However, the acceleration could be amplified while the excess pore water pressure was relatively small.(2) The peak value of excess pore water pressure ratio during earthquake is one of the main factors for the settlement of ground surface. Moreover, the main part of settlement occurred during the period of post-earthquake as the excess pore water pressure dissipated.(3) The comparison between the numerical simulation and the model test showed that the used cyclic mobility model could properly describe the seismic behavior of soil. The results also verified the validity of the used program DBLEAVES and FEM method.
引文
[1]曹振中,袁晓铭,陈龙伟,等.汶川大地震液化宏观现象概述[J].岩土工程学报,2010,32(4):645-650(Cao Zhenzhong,Yuan Xiaoming,Chen Longwei,et al.Summary of liquefaction macrophenomena in Wenchuan Earthquake[J].Chinese Journal of Geotechnical Engineering,2010,32(4):645-650(in Chinese))
[2]陈龙伟,袁晓铭,孙锐.2011年新西兰Mw6.3地震液化及岩土震害述评[J].世界地震工程,2013,29(3):1-9(Chen Longwei,Yuan Xiaoming,Sun Rui.Review of liquefaction phenomena and geotechnical damagein the2011 New Zealand Mw6.3 earthquake[J].World Earthquake Engineering,2013,29(3):1-9(in Chinese))
[3]黄雨,于淼,Bhattacharya S.2011年日本东北地区太平洋近海地震地基液化灾害综述[J].岩土工程学报,2013,35(5):834-840(Huang Yu,Yu Miao,Bhattacharya S.Review on liquefaction-induced damages of soils and foundations during 2011 of the Pacific Coast of Tohoku Earthquake(Japan)[J].Chinese Journal of Geotechnical Engineering,2013,35(5):834-840(in Chinese))
[4]Ishihara K,Araki K,Bradley B.Characteristics of liquefaction-induced damage in the 2011 great east Japan earthquake[M].Christchurch,New Zealand:University of Canterbury,2011
[5]凌贤长,郭明珠,王东升,等.液化场地桩基桥梁震害响应大型振动台模型试验研究[J].岩土力学,2006,27(1):7-10(Ling Xianzhang,Guo Mingzhu,Wang Dongsheng,et al.Large-scale shaking table model test of seismic response of bridge of pile foundation in ground of liquefaction[J].Rock and Soil Mechanics,2006,27(1):7-10(in Chinese))
[6]凌贤长,徐鹏举,于恩庆,等.液化场地桩-土-桥梁结构地震相互作用振动台试验数值模拟方法研究[J].地震工程与工程振动,2008,28(3):172-177(Ling Xianzhang,Xu Pengju,Yu Enqing,et al.Numerical simulation of shaking table test for seismicpile-soil-bridge structure interaction on liquefied ground[J].Earthquake Engineering and Engineering Dynamics,2008,28(3):172-177(in Chinese))
[7]Wang Rui,Zhang Jianmin,Wang Gang.A unified plasticity model for large post-liquefaction shear deformation of sand[J].Computers and Geotechnics,2014,59(3):54-66
[8]王睿,张建民.可液化地基中单桩基础的三维数值分析方法及应用[J].岩土工程学,2015,37(11):1979-1985(Wang Rui,Zhang Jianmin.Threedimensional elastic-plastic analysis method for piles in liquefiable ground[J].Chinese Journal of Geotechnical Engineering,2015,37(11):1979-1985(in Chinese))
[9]周燕国,李永刚,丁海军,等.砂土液化后再固结体变规律表征与离心模型试验验证[J].岩土工程学报,2014,36(10):1838-1845(Zhou Yanguo,Li Yonggang,Ding Haijun,et al.Characterization of reconsolidation volumetric strain of liquefied sand and validation by centrifuge model tests[J].Chinese Journal of Geotechnical Engineering,2014,36:1838-1845(in Chinese))
[10]Su Dong.Centrifuge investigation on responses of sand deposit and sand-pile system under multi-directional earthquake loading[D].Hong Kong:Hong Kong University of Science and Technology,2005
[11]苏栋,李相菘.可液化土中单桩地震响应的离心机试验研究[J].岩土工程学报,2006,28(4):423-427(Su Dong,Li Xiangsong.Centrifuge investigation on seismic response of single pile in liquefiable soil[J].Chinese Journal of Geotechnical Engineering.2006,28(4):423-427(in Chinese))
[12]Roscoe K H,Thurairajah A,Schofield A N,et al.Yielding of clays in states wetter than critical[J].Géotechnique,1963,3(13):211-240
[13]Schofield A N,Wroth C P.Critical state soil mechanics[M].London:University of Cambridge,1968
[14]Hashiguchi K.Constitutive equations of granular materials[J].Studies in Applied Mechanics,1983,7:127-136
[15]Asaoka A,Nakano M,Noda T.Superloading yield surface concept for highly structured soil behavior[J].Soils and Foundations,2000,40(2):99-110
[16]Zhang Feng,Ye Bin,Noda Toshihiro,et al.Explanation of cyclic mobility of soil:Approach by stress-dinduced anisotropy[J].Soils and Foundations.2007,47(4):635-648
[17]张锋.计算土力学[M].北京:人民交通出版社,2007(Zhang Feng.Computational Soil Mechanics[M].2007(in Chinese))
[18]王秋生,陈祖煜,隋海宾,等.离心机模拟中渗流相似率的试验验证[J].岩土工程学报,2011,33(8):1235-1239(Wang Qiusheng,Chen Zuyu,Sui Haibin,et al.Modelling seepage flow velocity in centrifuge models[J].Chinese Journal of Geotechnical Engineering.2011,33(8):1235-1239(in Chinese))
[19]王禹,高广运,顾晓强,等.渗透系数对砂土液化震陷影响的数值研究[J].岩土力学,2017,38(6):1813-1818(Wang Yu,Gao Guangyun,Gu Xiaoqiang,et al.A numerical study of the influence of permeability coefficient on the liquefaction-induced settlement of sands[J].Rock and Soil Mechanics,2017,38(6):1813-1818(in Chinese))
[20]Arulanandan K,Sybico J.Post-liquefaction settlement of sands[C]//Predictive Soil Mechanics Wroth.Oxford,England.1992.London:Thomas Telford Limited,1993
[21]Xia Zhifan,Ye Guanlin,Wang Jiahua,et al.Fully coupled numerical analysis of repeated shakeconsolidation process of earth embankment on liquefiable foundation[J].Soil Dynamics and Earthquake Engineering,2010,30:1309-1318.
[22]Bao Xiaohua,Ye Guanlin,Ye Bin,et al.Seismic performance of SSPQ retaining wall-centrifuge model tests and numerical evaluation[J].Soil Dynamics and Earthquake Engineering,2014,61/62:63-82
[23]Bao Xiaohua,Morikawa Y,Kondo Y,et al.Shaking table test on reinforcement effect of partial ground improvement for group-pile foundation and its numerical simulation[J].Soils and Foundations,2012,52(6):1043-1061
[24]Bhattacharya S,Hyodo M,Goda K,et al.Liquefaction of soil in the Tokyo Bay area from the 2011 Tohoku(Japan)earthquake[J].Soil Dynamics and Earthquake Engineering,2011,31(11):1618-1628
[2]陈龙伟,袁晓铭,孙锐.2011年新西兰Mw6.3地震液化及岩土震害述评[J].世界地震工程,2013,29(3):1-9(Chen Longwei,Yuan Xiaoming,Sun Rui.Review of liquefaction phenomena and geotechnical damagein the2011 New Zealand Mw6.3 earthquake[J].World Earthquake Engineering,2013,29(3):1-9(in Chinese))
[3]黄雨,于淼,Bhattacharya S.2011年日本东北地区太平洋近海地震地基液化灾害综述[J].岩土工程学报,2013,35(5):834-840(Huang Yu,Yu Miao,Bhattacharya S.Review on liquefaction-induced damages of soils and foundations during 2011 of the Pacific Coast of Tohoku Earthquake(Japan)[J].Chinese Journal of Geotechnical Engineering,2013,35(5):834-840(in Chinese))
[4]Ishihara K,Araki K,Bradley B.Characteristics of liquefaction-induced damage in the 2011 great east Japan earthquake[M].Christchurch,New Zealand:University of Canterbury,2011
[5]凌贤长,郭明珠,王东升,等.液化场地桩基桥梁震害响应大型振动台模型试验研究[J].岩土力学,2006,27(1):7-10(Ling Xianzhang,Guo Mingzhu,Wang Dongsheng,et al.Large-scale shaking table model test of seismic response of bridge of pile foundation in ground of liquefaction[J].Rock and Soil Mechanics,2006,27(1):7-10(in Chinese))
[6]凌贤长,徐鹏举,于恩庆,等.液化场地桩-土-桥梁结构地震相互作用振动台试验数值模拟方法研究[J].地震工程与工程振动,2008,28(3):172-177(Ling Xianzhang,Xu Pengju,Yu Enqing,et al.Numerical simulation of shaking table test for seismicpile-soil-bridge structure interaction on liquefied ground[J].Earthquake Engineering and Engineering Dynamics,2008,28(3):172-177(in Chinese))
[7]Wang Rui,Zhang Jianmin,Wang Gang.A unified plasticity model for large post-liquefaction shear deformation of sand[J].Computers and Geotechnics,2014,59(3):54-66
[8]王睿,张建民.可液化地基中单桩基础的三维数值分析方法及应用[J].岩土工程学,2015,37(11):1979-1985(Wang Rui,Zhang Jianmin.Threedimensional elastic-plastic analysis method for piles in liquefiable ground[J].Chinese Journal of Geotechnical Engineering,2015,37(11):1979-1985(in Chinese))
[9]周燕国,李永刚,丁海军,等.砂土液化后再固结体变规律表征与离心模型试验验证[J].岩土工程学报,2014,36(10):1838-1845(Zhou Yanguo,Li Yonggang,Ding Haijun,et al.Characterization of reconsolidation volumetric strain of liquefied sand and validation by centrifuge model tests[J].Chinese Journal of Geotechnical Engineering,2014,36:1838-1845(in Chinese))
[10]Su Dong.Centrifuge investigation on responses of sand deposit and sand-pile system under multi-directional earthquake loading[D].Hong Kong:Hong Kong University of Science and Technology,2005
[11]苏栋,李相菘.可液化土中单桩地震响应的离心机试验研究[J].岩土工程学报,2006,28(4):423-427(Su Dong,Li Xiangsong.Centrifuge investigation on seismic response of single pile in liquefiable soil[J].Chinese Journal of Geotechnical Engineering.2006,28(4):423-427(in Chinese))
[12]Roscoe K H,Thurairajah A,Schofield A N,et al.Yielding of clays in states wetter than critical[J].Géotechnique,1963,3(13):211-240
[13]Schofield A N,Wroth C P.Critical state soil mechanics[M].London:University of Cambridge,1968
[14]Hashiguchi K.Constitutive equations of granular materials[J].Studies in Applied Mechanics,1983,7:127-136
[15]Asaoka A,Nakano M,Noda T.Superloading yield surface concept for highly structured soil behavior[J].Soils and Foundations,2000,40(2):99-110
[16]Zhang Feng,Ye Bin,Noda Toshihiro,et al.Explanation of cyclic mobility of soil:Approach by stress-dinduced anisotropy[J].Soils and Foundations.2007,47(4):635-648
[17]张锋.计算土力学[M].北京:人民交通出版社,2007(Zhang Feng.Computational Soil Mechanics[M].2007(in Chinese))
[18]王秋生,陈祖煜,隋海宾,等.离心机模拟中渗流相似率的试验验证[J].岩土工程学报,2011,33(8):1235-1239(Wang Qiusheng,Chen Zuyu,Sui Haibin,et al.Modelling seepage flow velocity in centrifuge models[J].Chinese Journal of Geotechnical Engineering.2011,33(8):1235-1239(in Chinese))
[19]王禹,高广运,顾晓强,等.渗透系数对砂土液化震陷影响的数值研究[J].岩土力学,2017,38(6):1813-1818(Wang Yu,Gao Guangyun,Gu Xiaoqiang,et al.A numerical study of the influence of permeability coefficient on the liquefaction-induced settlement of sands[J].Rock and Soil Mechanics,2017,38(6):1813-1818(in Chinese))
[20]Arulanandan K,Sybico J.Post-liquefaction settlement of sands[C]//Predictive Soil Mechanics Wroth.Oxford,England.1992.London:Thomas Telford Limited,1993
[21]Xia Zhifan,Ye Guanlin,Wang Jiahua,et al.Fully coupled numerical analysis of repeated shakeconsolidation process of earth embankment on liquefiable foundation[J].Soil Dynamics and Earthquake Engineering,2010,30:1309-1318.
[22]Bao Xiaohua,Ye Guanlin,Ye Bin,et al.Seismic performance of SSPQ retaining wall-centrifuge model tests and numerical evaluation[J].Soil Dynamics and Earthquake Engineering,2014,61/62:63-82
[23]Bao Xiaohua,Morikawa Y,Kondo Y,et al.Shaking table test on reinforcement effect of partial ground improvement for group-pile foundation and its numerical simulation[J].Soils and Foundations,2012,52(6):1043-1061
[24]Bhattacharya S,Hyodo M,Goda K,et al.Liquefaction of soil in the Tokyo Bay area from the 2011 Tohoku(Japan)earthquake[J].Soil Dynamics and Earthquake Engineering,2011,31(11):1618-1628