【作者】 李健全；

【导师】 钱德玲；

【作者基本信息】 合肥工业大学 ， 岩土工程， 2010， 硕士

【摘要】 大量的地震震害调查研究表明,饱和砂土在地震作用下发生液化以及由液化引起的大变形是造成公路、桥梁、桩基等生命线工程严重破坏的主要原因之一。地震液化大变形的机理及影响因素比较复杂,是岩土工程和地震工程界的一个热点和难点。本文结合国家自然科学基金“桩-土-结构动力相互作用振动台试验”(No.40772171),以振动台模型试验为基础,采用有限差分程序FLAC3D,计算分析液化大变形下桩-土相互作用的动力响应。本文设计与制作了振动台试验模型,包括试验模型、材料性能参数、试验加载制度等,为下文利用FLAC3D程序进行模拟和验证提供了必要的计算参数。作者在试验模型的基础上对计算模型作出了一定的改进,以具有斜坡的临空面场地模型来更好地模拟地震液化下的大变形。研究表明临空面附近土体位移明显较大,且随着距离临空面距离的增加,土体位移反应减弱。本文利用FLAC3D程序计算了修改后的具有临空面场地的模型,着重研究了地震液化大变形下地基孔隙水压力的分布、地基土层对地震动的影响,得到软土尤其是液化土对地震波的传递有一定的减振隔震作用;通过桩基础的位移、弯矩和应变反应分析,表明软硬土层交界处及土层液化部位是桩身出现裂缝甚至断裂的主要位置,与试验后观察到的结果及历次桩基震害调查情况一致。所得结论对高烈度地震区桩基础的抗震设计具有一定的参考意义,在存在液化侧向扩展的地基中桩基础不仅要考虑上部结构的震动影响,还应考虑地基侧向位移对桩基础的影响。更多还原

【Abstract】 The large ground displacement induced by liquefaction of earthquake may result in serious damages to the life engineering such as highway,bridge and pile foundation. Liquefaction mechanism of large deformation and impact of these factors were complicated, and it had become a hot and big probloem in the geotech- nical engineering and earthquake engineering. The current research was supported by the National Science Foundation project of the shaking table test of pile-soil- structure interaction (No.40772171),calculated and analyzed the dynamic response of pile-soil interaction under the Large Ground Displacement induced by Eearth- quake Liquefaction by FLAC3D based on the model of the shaking table test.The design and production of the shaking table test is described in this paper,including the experimental model,the model material performance parameter,the experimental increase system. And it provided the necessary parameters to simulate and verify the shaking table model experiment by FLAC3D. This article made some improvements in the calculation model on the basis of the shaking test model,in order to have a free surface site models to better respond to large deformation under seismic liquefaction. We found that where near the free face significantly had a greater displacement,and with increasing distance from the free face,there is less displacement.In this paper,the revised model with a free face space was calculated with FLAC3D. That focused on the distribution of pore water pressure under the large ground displacement induced by earthquake liquefaction,and found that liquefied soil had a certain vibration isolation effect with the transmission of seismic waves. Through the analysis of displacement,moment and strain response of the pile foundation,this paper found the pile where are the junction of soft and hard soil, and liquefied soil,would have cracks and damage,with the test results and previous observations of the earthquake damage investigation in the pile. In the presence of liquid-side expansion foundation,pile foundation must consider not only the upper part of the structure of vibration,and also the impact of lateral displacement of the subsoil,this paper has a certain reference value to the seismic design of pile foundation in the high-intensity earthquake zone.更多还原