路堤震害模式及路堤动力特性研究

为研究强震区路堤的震害模式及动力特性，对汶川地震近场区路堤震害进行了调查，发现路堤震害以边坡上部拉裂、下部鼓张变形破坏模式为主，路堤震害严重程度与地震烈度、护坡措施和路堤本体加固措施关系密切，与路堤高度和地面横坡坡度关系不明显。利用振动台模型试验及数值模拟发现：加速度和动剪应力在路堤中上部增量最大、数值最大，且其最大值所在部位与拉裂缝出现部位基本一致；动土压力和位移在护坡道上方达到最大值，最大值部位与鼓张裂缝出现部位基本一致；张拉裂缝、鼓张裂缝均出现在距坡面3 m深度范围内，表明路堤损害是一种浅表层震害模式。通过动力数值计算，发现不同高度的路堤地面峰值加速度（PGA）放大系数形态呈现3种类型：沿程单调递增形态（h <10 m）、随高程增加而增加→衰减→增加的“三段形态”（h >20 m）以及介于前二者之间的过渡形态（10 m< h <20 m）。利用地震波传播理论对高路堤加速度反应机制进行了解释。

Research on seismic damage mode and dynamic characteristics of road embankment

To study the seismic damage mode and dynamic characteristics of road embankment, firstly, the road embankment seismic damage of Wenchuan Earthquake is investigated finding out that the main seismic damage type of road embankment is rip of upside and bulge of downside of the slope. Road embankment seismic damage is associated with seismic intensity, revetment measures, and reinforcement measures of road embankment noumenon closely, and has no significant relation with embankment height and crossfall of the ground. By means of shaking table model test and numerical simulation, it is found out that the magnitude and the increment of acceleration and dynamic shear stress are the largest in the upside of the road embankment, which is in the same position of the rip. Also, dynamic earth pressure and displacement are the largest above the berm, which is in the same position of bulge. All of rip and bulge are in the depth of 3 m, which show that the road embankment damage is a superficial zone damage. By dynamic numerical analysis finding out that magnification factor of peak ground acceleration (PGA) shows three types: monotone increasing as the height increases (h <10 m), increasing to decreasing and later increasing again as the height increases (h >20 m), and the form lies between the formers (10 m