CFG桩桩-网结构地基抗液化性能数值分析
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摘要
以京沪高速铁路液化土地基加固为背景,采用数值分析方法,通过各级加载情况下地基路基加固前后液化区域分布及超静孔隙水压力变化规律的分析,对水泥粉煤灰碎石桩(CFG桩)桩-网结构地基加固饱和粉土地基进行抗液化性能研究。研究表明,未加固饱和粉土地基在加载加速度大于0.2g时,几乎全部液化;加固后饱和粉土地基在加速度幅值为0.1g时,加固区以外的饱和粉土地基面附近有小面积的液化,随着加载加速度的增大,加固区以外的饱和粉土地基面积液化进一步加大,并逐渐向桩间土发展,当加速度幅值达到0.4g时,路基发生完全液化;超静孔隙水压力随加载加速度幅值的增加而增大。CFG桩桩-网结构地基能够有效地抑制超静孔隙水压力的上升,从而提高地基的抗液化能力。
The numerical simulation mainly researched on the liquefaction characteristics of cement fly-ash gravel pile(CFG pile) column-net composite foundation,with the saturated silty soil ground of the Beijing-Shanghai high-speed railway which was treated by CFG column-net composite foundation as the background.It has been plotted that the region of liquefaction distribution and the transferring rule of pore stress under a series of acceleration seismic loads in the treated and untreated foundation.The research results indicate that the untreated saturated silty soil ground is almost whole liquefaction when the amplitude of acceleration is more than 0.2g.Out of treated region is less liquefaction when the amplitude of acceleration is 0.1g after treated foundation.With the increase of acceleration,liquefaction region is further increased and gradually expand to the inter-pile-soil,and CFG column-net composite foundation is whole liquefaction when the amplitude of acceleration is 0.4g.Pore pressure is increased with the increasing of acceleration seismic load,and the increasing of excess pore water pressure can be restrained effectively by CFG pile column-net composite foundation,and the quality of liquefaction resistance is improved.
The numerical simulation mainly researched on the liquefaction characteristics of cement fly-ash gravel pile(CFG pile) column-net composite foundation,with the saturated silty soil ground of the Beijing-Shanghai high-speed railway which was treated by CFG column-net composite foundation as the background.It has been plotted that the region of liquefaction distribution and the transferring rule of pore stress under a series of acceleration seismic loads in the treated and untreated foundation.The research results indicate that the untreated saturated silty soil ground is almost whole liquefaction when the amplitude of acceleration is more than 0.2g.Out of treated region is less liquefaction when the amplitude of acceleration is 0.1g after treated foundation.With the increase of acceleration,liquefaction region is further increased and gradually expand to the inter-pile-soil,and CFG column-net composite foundation is whole liquefaction when the amplitude of acceleration is 0.4g.Pore pressure is increased with the increasing of acceleration seismic load,and the increasing of excess pore water pressure can be restrained effectively by CFG pile column-net composite foundation,and the quality of liquefaction resistance is improved.
引文
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[2]詹永祥,蒋关鲁,魏永幸.无碴轨道桩板结构路基在地震荷载下的动力响应分析[J].中国铁道科学,2006,27(6):22-26.(ZHAN Yongxiang,JIANG Guanlu,WEI Yongxing.Dynamic Response Analysis on the Pile-Plank StructureRoadbed of Ballastless Track under Earthquake Load[J].China Railway Science,2006,27(6):22-26.in Chi-nese)
[3]翟婉明.车辆轨道耦合动力学研究的新进展[J].中国铁道科学,2002,23(2):1-14.(ZHAI Wanming.New Advance in Vehicle-Track Coupling Dynamics[J].China Railway Science,2002,23(2):1*14.in Chinese)
[4]翟婉明,蔡成标,王其昌,等.列车提速对线路的动力影响研究与对策[J].中国铁道科学,2000,21(3):11-20.(ZHAI Wanming,CAI Chengbiao,WANG Qichang,et al.Dynamic Effects of Speed-Raise Train on Track and theCountermeasures[J].China Railway Science,2000,21(3):11-20.in Chinese)
[5]Oden J T,Pires E B.Algorithms and Numerical Results for Finite Element Approximations of Contact Problemswith Non-Classical Friction Laws[J].Computers&Structures,1984,19(1-2):137-147.
[6]Ishihara K,Yoshimine M.Evaluation of Settlements in Sand Deposits Following Liquefaction during Earthquakes[J].Soils and Foundations,1992,32(1):173-188.
[7]Popp K,Kruse H,Kaiser I.Vehicle-Track Dynamics in the Mid-Frequency Range[J].Vehicle System Dynamics,1999,31(5-6):423-464.
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