基于能量分析滑坡–隧道减震优化地震破坏特性试验研究

Experimental study on seismic failure characteristics optimization of landslide-tunnel shock absorption based on energy analysis

为探讨地震作用下隧道横穿滑坡区隧道结构的损伤变形特性,通过采用减震层来改善隧道结构的抗震性能,首次开展隧道下穿主滑面减震优化设计振动台对比试验。根据隧道结构加速度动态响应规律,提出一种基于希尔伯特–黄变换(HHT)和边际谱的能量识别方法来讨论隧道结构的地震损伤变形特性,并通过峰值傅里叶谱振幅(PFSA)对该方法的有效性进行验证。研究结果表明:(1)地震希尔伯特谱和边际谱能量的变化可以用来识别隧道结构的整体和局部变形,隧道结构的希尔伯特谱峰值区间的地震波频率为15~17Hz,而边际谱峰值区间的地震波频率为10~30 Hz。(2)减震层在低强度地震作用下减震效果明显,但随地震强度增大,减震层作用效果下降,且减震层对希尔伯特谱峰值空间分布态势影响较大,而对时间和频率的影响较小。(3)隧道结构首先在拱顶区域发生渐进累积损伤破坏,随地震强度增大,损伤部位向拱脚和仰拱区域发展,表现出区域性损伤破坏的空间耦合变形连续效应。(4)高频分量(>30 Hz)的地震希尔伯特能量主要引起隧道结构的局部损伤,低频分量(10~30 Hz)的边际谱能量放大了地表边坡的地震响应。(5)与希尔伯特能谱相比,边际谱代表各本征模态函数中一定的希尔伯特谱,具有丰富的频率分量和较高的识别度,可以清楚地反映隧道结构的能量传递和局部地震损伤特征。研究成果可为地震高烈度区隧道–滑坡的变形破坏模式预测及隧道抗减震技术设计提供理论参考。

In order to explore the damage and deformation characteristics of the tunnel structure across the landslide area under the action of earthquake,the seismic performance of the tunnel structure was improved by using the damping layer,the shaking table contrast test of the shock absorption optimization design of the tunnel under the main sliding surface was carried out for the first time.According to the dynamic response law of tunnel structure acceleration,an energy identification method based on Hilbert-Huang transform(HHT)and marginal spectrum was proposed to discuss the seismic damage deformation characteristics of tunnel structure,and the validity of this method was verified by peak Fourier spectrum amplitude(PFSA).The results show that:(1)The changes of seismic Hilbert spectrum and marginal spectrum energy can be used to identify the overall and local deformation of tunnel structure.The peak Hilbert spectrum interval of the tunnel structure has seismic wave frequencies of 15–17 Hz,while the peak marginal spectrum interval has seismic wave frequencies of 10–30 Hz.(2)The effect of the damping layer is obvious under the action of low intensity earthquake,but with the increase of earthquake intensity,the effect of the damping layer decreases,and the damping layer has a great influence on the spatial distribution of Hilbert spectrum peak,but has little influence on time and frequency.(3)The tunnel structure is firstly damaged by progressive cumulative damage in the arch region,and with the increase of seismic intensity,the damage site develops to the arch foot and elevation arch region,showing the continuous effect of spatial coupling deformation of regional damage and failure.(4)The seismic Hilbert energy of the high frequency component(>30 Hz)mainly causes local damage of tunnel structure,and the marginal spectral energy of the low frequency component(10–30 Hz)amplifies the seismic response of the surface slope.(5)Compared with the Hilbert energy spectrum,the marginal spectrum represents a certain Hilbert spectrum in each intrinsic mode function.It has rich frequency components and high recognition degree,which can clearly reflect the energy transfer and local seismic damage characteristics of the tunnel structure.The research results can provide a theoretical reference for the prediction of deformation damage mode of tunnel-landslide and the design of tunnel seismic mitigation technology in high seismic intensity areas.