相邻地形对地震动特性的影响分析

Analysis of the adjacent terrain effect on the properties of ground motion

基于采用透射人工边界的显式动力有限元方法,研究了相邻凸起地形对地震动反应谱特性的影响,分析了相邻凸起之间距离的变化对地形效应的影响。研究结果表明:1与单一凸起地形对地震动的放大效应相比,相邻地形的存在对地震动反应谱谱比曲线的形状影响不大,但对谱比的值具有较大影响,而且其影响程度的大小与地表观测点的位置有关;2相邻凸起地形的存在对凸起平台段中点地震动高频成分的放大效应影响较大,随着相邻凸起之间距离的增加,该影响逐渐减弱,多个相邻凸起构成的组合地形对地震动的放大效应逐渐接近单一凸起地形。

The explicit finite element analysis method combined with the artificial transmitting boundary theory is performed to evaluate the adjacent terrain effects on ground motion,and the influence of the distance between adjacent terrains on the topographical amplification effects is studied. The results show that：（ 1） Compared with the case of a single hill,the presence of adjacent hills has little effect on the shape of spectral ratio curve,but has significant effect on the value of spectral ratio,which is dependent on the locations of observation points.（ 2） The presence of adjacent hills has a greater effect on high-frequency ground motion,and with the increase of the distance between adjacent hills,such effect weakens gradually,and the effect of the composite topography combined with multiple hills on ground motion gradually approaches that of single hill.