双向地震作用对台阶型加筋边坡动力响应的影响

以我国西南部一实际工程为背景，分析了双向地震作用下台阶型加筋边坡的动力响应特点及规律。利用经过验证的PLAXIS有限元分析方法，首先在不同地震强度下，对比了水平及双向地震分别作用后加筋边坡的动力响应，然后研究了竖向地震的影响。结果表明，地震作用下，填土的塑性变形呈弥散型分布，随着竖向地震分量的增大，加筋土体横向变形增大，筋材内力提高，同时，竖向地震的震动压实作用使土体侧向围压提高，土体发生硬化，刚度增加，坡面横向位移减小；随着竖向地震分量进一步增大，土体硬化改变了边坡自振特性，在本研究地震激励下，加筋土体动力响应加剧，上坡有发生整体剪切破坏的趋势，并向外偏转，坡面横向位移增大。竖向地震对边坡动力响应的影响随地震强度的增大变得明显。

Influences of the Combined Horizontal and Vertical Excitations on the Seismic Responses of Tiered Geosynthetic Reinforced Slope

A validated finite element approach was employed to investigate the seismic responses of a tiered reinforced slope under the combined loading of horizontal and vertical excitations. The seismic performances with different earthquake intensities and different vertical excitations were analyzed. It is shown that the plastic deformation of the backfill soil distributed in a dispersed manner. With the increase of the vertical excitation intensity, the reinforcement loads increased. The earth pressure also increased due to soil compaction caused by vertical acceleration. The increase of earth pressure resulted in an increase of the soil stiffness, which led to a decrease of the surficial lateral displacement. But with a further increase of the vertical excitation intensity, the soil-hardening modified the natural vibration characteristics of the slope, which resulted in an aggravation in the seismic response. The upper tier tended to rotate externally and caused the increase of the surficial lateral displacement. With the increase of the earthquake intensity, the influences of the upper tier on the lower tier aggravated, and the influences of vertical excitation became more evident.