层状岩质斜坡竖向动力响应特性的振动台试验研究

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振动与冲击 ›› 2012, Vol. 31 ›› Issue (22) : 13-19.

论文

层状岩质斜坡竖向动力响应特性的振动台试验研究

刘汉香1，许强1，邹威2,徐鸿彪3

作者信息 +

Shaking table test study on the vertical seismic behavior for the layered rock slopes

LIU Han-xiang1, XU Qiang1, Zou Wei2, XU Hong-biao3

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文章历史 +

摘要

以‘5•12’汶川地震灾区典型斜坡岩体组合结构为模拟特征，采用水平层状上硬下软和上软下硬两种岩性组合概念模型，设计并完成了相应的大型振动台试验。基于有限元计算的模态分析及仪器记录结果表明，模型箱具有一定的刚度，既不会与模型产生共振，也不会产生明显放大效应。基于斜坡灾害中竖直向地震作用日益突出，而相关的试验研究又少，本文通过绘制不同振动强度下斜坡模型竖直向峰值加速度及其放大系数沿高程的变化规律曲线，揭示了正弦波尤其是汶川地震波作用下模型的竖直向加速度动力响应特性。主要结论为：（1）在两种波作用下，竖直向峰值加速度总体表现出高程放大效应，但基本上是模型下段放大速度稍快，而最大放大值则出现在中上部；（2）在汶川地震波作用下，随着振动强度增加，斜坡模型上段的峰值放大系数逐渐降低至趋于变化稳定，而下段基本不变，表明斜坡模型的高程放大效应逐渐减弱；（3）合成向地震波的作用强度大于单向地震波作用，但加载方向对竖直向加速度响应的规律性影响不明显；（4）上软下硬斜坡模型的竖直向加速度响应程度高于上硬下软斜坡模型。本文对斜坡竖直向加速度响应特性的研究将有助于人们更好地理解地震作用下一些由竖向地震力引起的变形破坏现象，同时也能够为斜坡动力稳定性计算中竖直向地震力的取值提供一定的参考价值。

Abstract

A large scale shaking table test was conducted on two 1:100 scaled slopes, which have the lithological combinations of hardness-upward or softness-upward formed broadly in 2008 ‘5.12’ Wenchuan Earthquake areas, Sichuan Province, China. Ruled by Buckingham π’ s similitude theorem, waves of different kinds, directions and amplitudes were inputted at the base of models. Modal test result based on FEM and instrumental records shows that the model box has enough rigidity without resonance with model slopes and amplification itself during shaking. With the more and more importance of vertical ground motion and its lack of test study, in this paper, based on the recorded data, the peak vertical accelerations and their amplification factors along different elevations were mapped under incremental excitation levels, when subjected to sine waves especially to real waves scaled from Wenchuan Earthquake waves. Results show: (1) the amplification effect occurs in vertical components with increasing elevations, however, the amplifying speed in the upper part is basically smaller than that in the lower part of model slopes, though the maximum amplification occurs in the upper part; (2) when excited by Wenchuan earthquake waves, the amplification factors in the upper part decrease gradually to a final stable state while those in the lower part has little change with increasing excitation intensity, which indicates the attenuation in amplification effect; (3) responses under earthquake waves in combinational directions are stronger than those in vertical direction only, but the difference in excitation directions has little effect on the change laws of vertical accelerations. (4) Responses in the softness-upward model slope are stronger than those in the hardness-upward model slopes. Results provide a good understanding of the damage caused by vertical component of earthquake, and also a guide to select the more reasonable vertical seismic coefficient during dynamic slope stability calculation.

导出引用

刘汉香;许强;邹威;徐鸿彪. 层状岩质斜坡竖向动力响应特性的振动台试验研究[J]. 振动与冲击, 2012, 31(22): 13-19

LIU Han-xiang;XU Qiang;Zou Wei;XU Hong-biao. Shaking table test study on the vertical seismic behavior for the layered rock slopes[J]. Journal of Vibration and Shock, 2012, 31(22): 13-19