含隧道岩石边坡在地震作用下动力响应特性研究

Study on dynamic response characteristics of rock slope with tunnel under earthquake

根据动力有限元原理,利用软件Midas/GTS对某一山岭高速公路隧道边坡,模拟有无锚杆加固两种工况,进行了地震荷载作用下的动力响应分析,获得了位移、加速度、锚杆轴力及隧道的动力响应规律。结果表明:边坡岩体对地震加速度存在放大作用,锚杆在一定范围内能有效抑制这种放大作用;锚杆加固岩质边坡主要体现在对地震作用下坡顶岩体产生拉剪破坏的嵌固作用,来约束周围岩体的位移,锚杆支护设计的关键在于充分发挥锚杆的延性;在地震作用下隧道动力响应由洞口向衬砌内部,拱脚向拱顶呈放大趋势,衬砌内出现明显的应力集中现象。

On the basis of dynamic finite element theory, the dynamic response of a rock slope cut through by a mountain expressway tunnel was analyzed under earthquake load with Midas/ GTS software by simulating whether reinforcement is anchored or not. The change rules of acceleration, displacement, axial force of anchor bott and the dynamic response of tunnel were obtained. The results indicated that, the rock slope had an amplification effect on seismic acceleration and the amplification effect could be suppressed effectively by rock bolts in a certain range. The reinforcement effect of bolt was achieved through reducing the tension - shear damage of slope rock mass under seismic load. The key of bolt support design was to give full play to its ductility. The dynamic response of the tun- nel under earthquake exhibited an amplification trend from the entrance to the interior lining and from the foot to the crown of the arch with the evident phenomenon of stress concentration within the lining.