隧道洞口部边坡动力响应特性振动台试验研究

Experimental Study with Vibrating Table on Dynamic Response Characteristics of Side Slopes at Tunnel Portals

我国西南地区建有大量的公路、铁路隧道工程,地震条件下隧道洞口部边坡的动力响应特性不仅控制边坡的变形破坏机制,而且也是隧道洞口部边坡动力支护设计的依据。采用大型振动台模型试验,对隧道洞口部边坡加速度及位移动力响应特性进行研究,并对比分析不同地震波波形的输入对边坡动力特性的影响。结果表明:与一般公路及建筑边坡不同,隧道洞口部边坡坡面的响应加速度具有先增大再减小再增大的特性;边坡动力支护设计采用单一峰值是偏于危险的,应综合考虑多种波形的影响。位移监测结果表明:地震波较小时边坡坡顶变形比较明显,但随着地震波幅值的增加,隧道洞口部边坡坡脚的变形急剧增加且超过了坡顶变形,因此应增强边坡坡脚的支护强度。

In south -west regions of China a lot of highway and railway tunnel projects are constructed, the dynamic response characteristics of side slopes at tunnel portals under the seismic conditions not only control failure mechanisms of side slopes, but also are bases for design of dynamic supports of side slopes at tunnel portals. This paper adopts large - scale vibrating table model test to study dynamic response characteristics of acceleration and displacement of side slopes at tunnel portals and comparatively analyzes influences of input of different seismic waveforms on dynamic characteristics of side slopes. The results show that the acceleration exhibits the characteristic of increase - decrease - increase on surface of side slopes at tunnel portals, which is different from side slopes of general highways and buildings; single peak value adopts in design of dynamic supports of side slopes is at risk, and influences of multiple waveforms should be comprehensively considered. The displacement monitoring results show that the top deformation of side slopes is obvious when seismic waveforms are small, but the deformation of at the foot of side slopes at tunnel portals sharply increases with increase of the amplitude of seismic waveforms and exceeds the top deformation, therefore, the supporting strength for the foot of side slopes should be enhanced.