地震作用下柔性挡墙变形特征分析

为研究柔性挡墙的地震动力响应及变形特征,开展格宾加筋挡墙与生态加筋挡墙的大型振动台模型试验。研究结果表明:在地震作用下,2种柔性挡墙受到的峰值动土压力沿墙高呈现中间小两端大的分布特征,这与混凝土刚性挡墙峰值动土压力的分布规律恰好相反。由于格宾加筋挡墙和生态加筋挡墙的面墙在地震作用下发生鼓胀变形,导致其相应部位的动土压力远小于混凝土挡墙的动土压力。国内现行规范因未考虑柔性挡墙变形后的地震土压力衰减效应,据此进行柔性挡墙的抗震设计将偏于保守。通过分析认为,对于格宾加筋挡墙和生态加筋挡墙这类面墙刚度较小的柔性挡墙的抗震设计,应在保证挡墙地震稳定性的前提下,对地震土压力做适当的折减以节约工程造价。对于铁路及高等级公路柔性挡墙的抗震设计,除要保证其整体稳定性外,还需控制墙体的局部变形量,改善填料的工程特性和增加面墙材料的弹性模量以及加厚墙体均可以减小挡墙在地震作用下的变形量。

RESEARCH ON SEISMIC DEFORMATION CHARACTERISTICS OF FLEXIBLE WALL

In order to study the earthquake dynamic response and deformation mechanism of flexible wall,the large-scale shaking table model tests for reinforced gabion wall and reinforced ecological wall were performed.The results showed that the distribution of horizontal peak dynamic earth pressures along height is with large value at both ends and small value at the middle for the two kinds of flexible walls,which is contrary to the distribution of horizontal peak dynamic earth pressures of rigid retaining wall.Due to the bulging deformation under earthquake,the value of horizontal peak dynamic earth pressures of the reinforced gabion wall and reinforced ecological wall is substantially smaller than that of rigid retaining wall.The national standard does take into account the effect of seismic earth pressure attenuation after deformation of flexible wall,the seismic design of flexible wall according to the current standard is conservative.Through analysis,to the flexible wall such as reinforced gabion wall and reinforced ecological wall,in ensuring the seismic stability of the premise,the seismic earth pressures can be reduced properly to save cost.For the seismic design of flexible wall in railway and highway,while maintaining the integral stability of the flexible wall,local-deformation control should be paid attention to too,improving the engineering properties of filling materials and increasing elastic modulus of walling materials as well as thickness of the wall can reduce the displacement of the flexible wall.