基于振动台试验的水平层状边坡共振响应分析

Resonance response analysis of horizontal layered slope based on shaking table tests

共振现象已经多次在汶川震害调查中被发现,其在结构工程中已经得到了广泛的研究,但在边坡工程中尚未开展深入的研究。采用振动台模型试验开展水平层状边坡的固有振动特性及其共振响应研究。首先分别通过白噪声激振、正弦波扫频和天然波激振获取边坡的固有频率,讨论不同方法在获取边坡固有频率方面的优劣性。其次,通过输入不同频率、不同幅值的正弦波激励,研究边坡的动力响应特征,重点关注边坡在共振频率处的加速度和位移响应特征。结果表明:白噪声激振和扫频试验分析结果较为接近,且白噪声激振对于边坡固有频率的变化识别更为敏感,天然波谱比曲线由于出现多个峰值,导致固有频率的确定较为模糊。边坡在其固有频率处存在共振响应现象,表现为边坡加速度峰值放大系数和位移响应峰值在共振频率段会出现峰值集聚,且相较于高程效应,共振对边坡响应的放大效应具有主导作用,会加剧边坡在振动作用下的变形破坏。研究有助于从边坡共振的角度揭示边坡的地震响应特征,也可以为边坡的抗减震研究提供思路。

Resonance phenomena have been found many times in Wenchuan earthquake damage surveys,and they have been extensively studied in structural engineering,but in-depth research has not yet been carried out in slope engineering.In this paper,the inherent vibration characteristics and resonance response of horizontal layered slopes are studied by shaking table model tests.Firstly,the natural frequency of the slope is obtained by white noise excitation,sinusoidal sweep wave excitation and natural wave excitation,and the advantages and disadvantages of different methods in obtaining the natural frequency of the slope are discussed.Secondly,by entering sine wave excitations of different frequencies and different amplitudes,the dynamic response characteristics of the slope are studied,focusing on the acceleration and displacement response characteristics of the slope at the resonance frequency.The results show that the results of the white noise excitation and sweep tests are relatively close,and the white noise excitation is more sensitive to the change of the natural frequency of the slope,and the determination of the natural frequency is blurred due to the occurrence of multiple peaks in the natural spectral ratio curves.The resonance response phenomenon of slope appears at its natural frequency,showing that the amplification coefficient of peak acceleration and peak displacement of slope will peak in the resonance frequency segment.Compared with the elevation effect,resonance plays a leading role in the amplification effect of slope response,which will aggravate the deformation and failure of slope under vibration.This work helps to reveal the seismic response characteristics of slopes from the perspective of slope resonance,and can also provide ideas for slope seismic mitigation studies.