【作者】 王斌；

【导师】 刘松玉； 童立元；

【作者基本信息】 东南大学 ， 岩土工程， 2005， 硕士

【摘要】 我国是一个多地震国家,同时也是世界上地震灾害最严重的国家之一,地震经常威胁着人民的生命和财产安全。随着我国经济建设的飞速发展,许多大型基础设施工程得以兴建,地震对我国正在蓬勃发展的基础设施建设安全构成了严重的潜在威胁。大量的地震震害调查结果表明地震时由于液化引起的地面大变形(Large Ground Deformation,简称LGD)是造成高速公路工程震害和结构破坏的主要原因之一。本文针对地面大变形的预测理论及其对高速公路工程的影响问题进行了研究。(1)对国内外关于液化引起地面大变形的预测理论和试验研究的现状进行了全面地回顾与总结,对研究中存在的主要问题进行了初步分析;(2)在此基础上,研究了一种利用标准贯入试验和静力触探试验进行地震液化大变形预测的方法,并利用这两种方法对宿淮高速公路部分可液化地段可能会发生液化大变形的大小进行了预测。分析认为,这两种方法可以在高烈度地震区高速公路工程建设中推广应用;(3)利用拉格朗日有限差分法对可液化场地在地震作用下发生地面大变形的过程进行了数值模拟与仿真,分析了各影响因素对地面大变形的影响。研究认为具有临空面的场地,临空面的倾斜率愈大则产生的地表侧向位移值愈大;地表倾斜较陡的场地极易遭受地震作用而破坏,工程建设应避开此类场地;震动持续时间长且释放能量高的地震对场地以及场地中工程设施的破坏是致命的,应做好地震预报工作并积极准备应对措施。(4)回顾了水平荷载作用下桩基础的理论研究方法和桩土共同作用的离心模型试验,利用有限差分法模拟了桥梁桩基础在地震动力作用下场地发生侧向位移时的桩身内力变化。研究表明在发生液化地面大变形之后,桩基础在可液化土层范围内会产生超过本身极限抗弯能力的弯矩,易发生弯剪破坏。并指出在有液化侧扩地基中的桩基础设计不能仅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。所得结论对高烈度地震区桥梁桩基础的抗震设计具有一定的指导意义;(5)本文根据对地震液化引发地面大变形的产生机理和影响因素分析,归纳总结了防治地面大变形及减小桥梁桩基震害的工程措施,对高速公路工程抗震设计具有一定指导意义。最后对今后这方面的研究提出了建议和展望。更多还原

【Abstract】 In the past few years, there were lots of earthquakes happened in China. Meanwhile, our country is one of the nations that have the most serious earthquake disasters in the world. The earthquake usually threatens domestic life and property safety. Recently, many large-scale facilities have been built owing to economic developments at very fast speed in China. So the frequent earthquake is a serious latent threat to the safety of facilities construction which is in booming development. The particular history reports of earthquake disaters have illuminated that damage to pile foundations and structuces may be caused by large ground deformation (LGD) due to seismic liquefaction. This kind of damage has been observed many times in several strong earthquakes in the past. The prediction method of large ground deformation and its effect on highway engineering are researthed in this paper.(1) Based on the review of the theoretic and testing research on large ground deformation induced by seismic liquefaction, a comprehensive introduction is given to the problems of this research such as the earthquake disaster induced by large ground deformation; the methods to predict the large ground deformation and the testing on it; the character of the highway engineering during the seismic liquefaction and the different ground improvement measures against large ground deformation.(2) Then an approach to estimate liquefaction-induced ground deformations using either CPT or SPT data is recommend. And the approach is applied to predict the potential LGD which may happen on the partial region of the Su-huai highway. The outcome indicates that the proposed approach combines available results from laboratory test, capture the mechanisms of liquefaction-induced lateral spreads, and characterize the major factors influencing LGD. Furthermore this method is relatively simple and can be applied with only a few additional calculations following an SPT- or CPT-based liquefaction-potential analysis.(3) The generant process of LGD induced by seismic liquefaction is simulated by making use of Lagrangian finite difference software-FLAC3D, the effect of various parameters on the lateral spread is also analysed qualitatively.(4) The behavior and the characteristic of pile foundation for bridge that is suffering from LGD due to seismic liquefaction is analysed by using FLAC3D. The research shows that there may be excessive bending moment happened in the interfaces between lipuefied and nonliqufied soil layers. So the design of pile foundation should not just consider the dynamic effect of the superstructure. The effect of lateral spread on pile foundation can not be neglected.(5) According to the analysis of the creation mechanisms and the influence factor of the lateral spread due to seismic liquefaction, several effective engineering measures that can prevent the ground and pile foundations form earthquake disaster are propoused. Finally, some favorable suggests and prospects on the following research of this aspect are put forward.更多还原