Residual deformation assessment of earth structure against earthquake and its application for design

本文提出了土体结构抗震稳定和刚塑性动力变形分析的新方法，并讨论了它们在实践中的适用性。考虑土结构抗震安全系数基于安定理论的一种新的稳定方法，它准确地考虑了地震的加速度时程。对基岩上施加的正弦和不规则加速度波的适用性进行了检验。本文的研究结论如下：1)合理地评价了强迫加速周期对路堤稳定性的影响。稳定性不仅取决于地面的强迫加速度，还取决于地面的动力特性。2)通过与传统地震系数法的比较，讨论了新方法的适用性。刚塑性动力变形分析的发展基于刚塑性假设的动力变形分析是为评估土体结构在地震作用下的残余变形而发展起来的。1)刚塑性动力变形分析能够较好地模拟岩土结构在刚体和塑性流动之间的运动状态。2)采用重复荷载作用下粘土的应力历史模型，通过刚塑性动力变形分析，较好地模拟了平面应变重复试验的液化过程。

This study presents new stability methods of earth structures against earthquakes and rigid-plastic dynamic deformation analysis, and discusses their applicability in practice.1. Consideration on safety factor of earth structure against earthquakesA new stability method based on the shakedown theory considers the acceleration time history of earthquake exactly. The applicability of this method is examined for both sine and irregular acceleration waves enforced at the bedrock. The conclusions in this study were as follows : 1) The effects of periods in enforced accelerations on embankment stability were suitably evaluated. The stability depended on not only the enforced acceleration, but also the dynamic properties of the ground. 2) The applicability of new method is discussed in comparison with the conventional seismic coefficient method.2. Development of rigid-plastic dynamic deformation analysisThe dynamic deformation analysis based on rigid-plastic assumption was developed in purpose of residual deformation assessment of earth structure against earthquakes. The results obtained in this study were as follows : 1) THe rigid-plastic dynamic deformation analysis could simulate the behavior of the geotechnical structures properly which changes their states between rigid body and plastic flow. 2) With the use of the stress history model of clays for repeated loads, the liquifaction process of plane strain repeated test was fairly simulated by rigid-plastic dynamic deformation analysis.