爆破地震波穿越边坡软弱夹层时的衰减特征

为防止含软弱夹层的岩质边坡受爆破地震波的影响发生滑动变形而失稳,形成滑坡灾害,研究了地震波穿越软弱夹层时的衰减特征。建立相似实验模型和动力有限元数值模型,对软弱夹层两侧岩体的振动速度、加速度进行了对比。结果表明,地震波穿过软弱夹层后其振动速度和加速度显著减弱,软弱夹层与两侧岩体的波阻抗比值越小,地震波振动速度衰减程度越高,若夹层与两侧岩体的波阻抗之比达到1∶10以上时,振动速度可降低80%以上。地震波穿过顺倾软弱夹层时衰减幅度较反倾夹层略大。由于软弱夹层振动幅值发生突变,软弱夹层内产生了附加剪切作用力,可导致软弱夹层的损伤或破坏。

Attenuation characteristics of blasting seismic waves passing through weak interlayer

In order to prevent the rock slope with weak interlayer from the impact of blasting seismic wave and occurrence of landslide hazard caused by sliding deformation and instability,the attenuation characteristics of blasting seismic waves passing through weak interlayer is studied.Some physical experiment models and dynamic finite element models are built to compare the vibration velocity and acceleration of the rock mass on both sides of the weak interlayer.The experimental results show that the velocity and acceleration of the seismic waves are weakened when the seismic waves passing through the weak interlayer.The more the ratio of the wave impedance of the interlayer and the rock mass,the more seismic attenuate.The vibration velocity will decrease more than 80% when the ratio of the wave impedance of the interlayer and the rock mass on reaches 1∶10.The attenuation amplitude of the seismic wave which passes through the down dip interlayer is stronger than the inversely dip interlayer.Due to the abrupt change of the vibration amplitude of the weak interlayer,additional dynamic shear stress is produced which can lead to the damage or failure of the weak interlayer.