深切谷坡浅表部卸荷裂隙发育,风化强烈,致使浅表层介质性质出现差异,成为非连续介质,地震动力响应由此变得复杂.根据青川地震监测数据分析线型坡及山坳处的地震动力响应特征,并结合适用于分析岩质边坡运动过程的不连续变形分析方法(DDA),对不同岩质边坡及岩体中出现节理和软弱夹层等不利地质体时的动力特征进行分析,揭示在一定高程下线型坡上地震波加速度随高程增加而增大,且垂直山脊方向的地震波峰值加速度放大系数大于沿山脊方向,最大可达3.12倍;山坳处的地震波加速度较谷底会出现一定程度的衰减.同一规模边坡,岩质越硬加速度放大系数越大;当边坡中存在节理及软弱夹层时,地震波传播会受到反射和透射的影响,从而影响边坡的动力响应特征.分析表明,岩体弹模较大时,节理对地震波传播的透射作用较强,且节理间距与输入波长的比值小于临界值时,其比值越大,节理对地震波的透射作用越强;岩体分界面下部岩性较上部岩性硬时,随着两种岩性弹模差别增大,透射波峰值加速度降低越明显,而反之分界面以下岩性较上部软时,随着两种岩性弹模差值越大,透射波加速度放大越显著;软弱夹层厚度以及其与周围岩体波阻抗比较大时,地震波经过软弱夹层时的透射系数较小.%In the superficial part of the deep valley,the unloading fractures are developed and the weathering is intense.As a result,the superficial layer becomes a discontinuous medium and the nature of the medium is different.Thus the seismic response becomes complicated.Based on the Qingchuan earthquake monitoring data,the seismic response characteristics of linear slope and col are analyzed,and combined with the discontinuous deformation analysis (DDA) which is suitable for analyzing rock slope movement process,the dynamic characteristics of different rock slopes and rock masses are analyzed when there are joint and weak interlayer and other unfavorable geologic bodies.It is revealed that the acceleration of seismic wave on the linear slope of a certain elevation increases with the elevation,and the peak acceleration amplification coefficient of the seismic wave in the direction of vertical ridge is larger than that of the seismic waves along the ridge,and the maximum is 3.12 times;The acceleration of the seismic wave at the col is attenuated to a certain extent compared with that of seismic wave at the bottom;In the same scale slope,the harder the rock mass is,the larger the acceleration amplification coefficient is;When there are joints and weak interlayers in the slope,the seismic wave propagation will be affected by the reflection and transmission,thus affecting the dynamic response characteristics of the slope.The analysis shows that when the elastic modulus of the rock mass is large,the transmission effect of the joint on seismic wave propagation is stronger,and when the ratio of joint spacing and input wavelength is less than critical value,the greater the ratio is,the stronger the transmission effect of the joint on the seismic wave;When the lithology of the lower part of the rock is harder than that of the upper part of the rock,with the increase of the difference between the two elastic modulus of the rock mass,the decrease of the peak acceleration of the transmitted wave is more obvious.While on the contrary,the lithology of the lower part of the rock is softer than that of the upper part of the rock,with the increase of the difference between the two elastic modulus of the rock mass,the acceleration of the transmitted wave increases more obviously.When the thickness of the weak interlayer and the wave impedance between the weak interlayer and the surrounding rock mass are relatively large,the transmission coefficient of seismic waves passing through the weak interlayer is smaller.
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