强震作用下深厚砂质覆盖层土坝有效应力动力分析

Effective Stress Analysis of an Earth Dam on Deep SandyAlluviums During Strong Earthquakes

摘要:

利用基于Biot的饱和多孔介质理论和砂土多重机构模型的动力分析有限元程序FLIP,对遭受M6.7地震的国外某深厚砂质覆盖层土坝进行有效应力动力分析,研究坝体和地基的动力反应特性及其超静孔隙水压力的分布规律。通过对坝体加速度和永久变形的计算结果与现场实测数据的比较分析,证明两者之间存在一定差异,但计算结果基本上反映坝体加速度与永久变形的实际分布特征,从而说明采用的数值计算方法和本构模型具有一定精度。根据计算结果可以得出:坝体无液化发生;坝底上游浅层地基可能会发生局部液化,但范围较小,可以不进行加固处理;坝趾附近浅层地基可能会发生较大范围的液化,因此须采取相应的抗液化加固措施。

Abstract:

Using the finite element liquefaction program based on Biot's dynamic theory for fluid-saturated porous media and a multimechanism constitutive model for sandy soils, dynamic effective stress analysis of an earth dam on deep sandy alluviums during an M6.8 earthquake is conducted.A comparison of calculated and measured values shows some differences in acceleration and permanent deformation.Because the calculated values essentially reflect actual distribution, the accuracies of the numerical and constitutive models are validated.On the basis of the numerical analysis results, it can be concluded that a reinforcement measure for the dam and its underlying foundation is unnecessary because liquefaction in only a small area may occur in these zones. However, an anti-liquefaction reinforcement measure should be taken because liquefaction in large areas may occur in the shallow layers of sandy alluviums near the dam toe.