【摘要】 采用以广义Biot固结原理和Pastor-Zienkiewicz Mark-Ⅲ广义塑性本构模型为基础的动力有限元分析方法,研究了U形碎石排水对液化土中地下管线上浮的减灾效果及机理.U形排水带由2个竖向1个横向排水层构成.通过参数分析,讨论了竖向排水带宽度、竖向排水带与管线的距离、水平排水带厚度、排水碎石渗透系数等因素对地震时管线上浮位移的影响.研究结果表明:采用基于广义塑性本构模型的动力有限元分析方法可以很好地模拟地震时地下管线发生的上浮现象;在管线周围设置U形排水带明显降低了管线的上浮位移;排水带渗透系数对管线上浮位移的影响较大;合理地设计排水带的几何尺寸和渗透系数可有效地控制管线的上浮位移.更多还原

【Abstract】 Based on the generalized Biot theory of consolidation and generalized Pastor-Zienkiewicz Mark-Ⅲ plasticity constitutive model,finite element procedure was used to study the effectiveness of a U-shape gravel drainage band as a mitigation method against the up-lifting of pipelines buried in liquefiable soil. Since the U-shape drainage band was made of two vertical and one horizontal drainage layers,parametric studies were conducted to investigate the influence factors in preventing pipeline up-lifting during earthquake. The influence factors include the width of the vertical drainage band,the distance between the vertical drainage band and pipeline,the thickness of the horizontal drainage band and the permeability of the gravel drainage band. Numerical results indicate that the finite element procedure based on the generalized plasticity constitutive model can very well simulate the floatation of a buried pipeline during an earthquake. To prevent the up-lifting of pipelines during earthquake,the U-shape drainage band surrounding a pipeline performs satisfactorily. The permeability of the gravel drainage plays an important role in pipeline up-lifting mitigation. Thus,the up-lifting of a pipeline during an earthquake can be prevented when appropriate dimensions and permeability of the U-shape drainage band are designed.更多还原