边坡地震动放大效应的研究是开展边坡抗震设计的基础。提出基于白噪声的地震动荷载反演方法,通过动力学计算和频谱分析发现边坡具有宽频带反应体系的特性,单面均质边坡在坡肩处的放大系数最大且通常不超过2.0。较之于考虑行波效应的地震动输入方式,采用时空一致地震动输入的计算结果偏保守。地震波频谱特性对放大系数影响的研究表明,抗震设计中应依据边坡所在场地的设计地震分组确定放大系数。通过引入一个与周期同量纲的参量来综合反映坡高、坡度和岩体波速对坡肩放大系数的影响,并针对Taft波和El Centro波分别计算获得了坡肩水平向放大系数的谱曲线。放大系数的包络分析表明边坡表面的放大系数通常不超过1.85。研究结果可为均质岩体边坡的抗震设计提供理论依据与技术支持。
The study of ground motion amplification effect is basis of the slope seismic design. An inversion method of seismic load is proposed based on white noise. The dynamic response calculation of slopes and spectrum analysis show that rock slopes have the characteristics of broadband reaction system. In the crest of single-faced rock slope, the amplification factor reaches the maximum value, and is generally less than 2.0. Compared with the results of the seismic input of traveling wave effect, those of time-space consistency input are conservative. Moreover, the influence of seismic wave spectral characteristics on the amplification factor is studied. In the seismic design, amplification factor should be determined by design earthquake group of site at which slope is located. A parameter that has the same dimension with period is introduced in order to comprehensively reflect the influence of slope height, gradient, and rock mass wave velocity on the amplification factor in the crest of slope. Furthermore, Taft wave and El Centro wave are specified to calculate the spectrum curve of horizontal amplification factor in the crest of slope. The envelope analysis indicates that the amplification factor in the surface of slope is less than 1.85. The results of this study can provide a theoretical basis and technical support for the seismic design of homogeneous rock slope.