二级支护边坡重力式挡墙地震动力特性的振动台试验研究

Large-scale shaking table test study on seismic response characteristics of gravity retaining walls of slopes stabilized by two-stage retaining structures

根据顺层岩石倾角20°,30°和40°,设计了3个比尺为1∶8、重力式挡墙与格构式锚杆框架结构二级组合支护的厚覆盖层与顺层岩石边坡模型,开展了3个大型振动台模型试验,对比研究多级支护和不同顺层岩石倾角条件下重力式挡墙的地震动力响应特性。大型振动台模型试验以汶川波作为激振波,采用水平(X)向、竖直(Z)向和水平竖直(XZ)双向等三种激振方式,测试了重力式挡墙加速度、动位移和动土压力响应特性。通过分析加速度动力响应特性,得到了加速度放大系数随激振方式、激振加速度峰值、墙高和顺层岩石倾角的变化规律;通过分析动位移响应特性发现,重力式挡墙主要产生水平向动位移响应和动位移模式,且主要由水平向激振所产生,其动位移响应特性、动位移模式不因激振方式、岩层倾角而变化;通过对动土压力响应特性分析,得到了不同岩层倾角、激振方式条件下的动土压力沿墙高分布形式,以及动土压力响应峰值与岩层倾角、激振方式的变化规律。试验研究结论为二级支护边坡中重力式挡墙抗震设计及其地震动力反应特性的进一步研究奠定了良好的基础。

Three slope models with the geometric scale of 1∶8of thick soil cover and bedding rock,and with different consequent rock angles 20°,30°,and 40°,were designed respectively.Three large-scale shaking table model tests,which use the Wenchuan seismic waves as excitation sources and apply the exicitation from three kinds of directions including X,Z,and XZ both,were performed to study comparatively the seismic response characteristics of the gravity retaining wall of two-stage retaining structures comprising the gravity retaining wall and the anchor lattice frame structure.Based on seismic acceleration response analysis,the response characteristics of the amplification coefficients of the gravity retaining wall with respect to the excitation direction,the peak excitation acceleration,the height of retaining structure and the consequent rock angle,are obtained respectively.The results of seismic displacement response analysis indicate that the horizontal seismic displacement response and seismic displacement mode occur most and are triggered by the X-direction excitation mainly.The seismic displacement response characteritics and seismic displacement mode of the gravity retaining wall don't change with the variation of the excitation direction and consequent rock angle.The study of seismic earth pressure response characteristics is also conducted,and the distribution of seismic earth pressure and the variation characteristics of the peak seismic earth pressure with respect to the consequent rock angle and the excitation direction are obtained.This study can provide a good foundation for seismic design and further research of seismic response characteristics of two-stage retaining structures comprising the gravity retaining wall and the anchor lattice frame structure.