【摘要】 通过在四川省泸定冷竹关沟两岸斜坡不同部位挖掘平硐并放置强震监测仪器的方法,对"4.20"芦山地震在该峡谷两侧斜坡的地震动响应特征、地形放大效应等进行研究。根据7台地震仪器所记录的芦山主震数据,冷竹关沟右岸1#监测点PGA水平分量为1.64m/s2,竖直分量为0.67m/s2,明显高于其他监测点的PGA值(0.11～0.42m/s2)。参照康定姑咱强震台主震记录,1#监测点PGA放大系数达到6.9,其阿里亚斯强度放大数十倍。谱比分析(HVSR)显示,1#监测点谱比分析的水平分量地形放大系数达到9.0,2#监测点地形放大系数为3.5,左岸4#～7#监测点地形放大系数一般在1.0～3.0。研究表明,强震条件下冷竹关右岸单薄山梁地震动地形放大效应明显强于左岸中高山斜坡,且1#监测点的凸出地形放大效应最大。随着振幅值的放大,强震动能量以数十倍效应剧增,当短时间内积聚的振动能量超过或远远超过岩土体介质的强度时,易形成震裂、崩塌、滑坡及高陡地形的抛射效应。更多还原

【Abstract】 Adits were excavated in different parts of the slopes on both banks of the Luding Lengzhuguan valley and the earthquake monitoring instruments were placed in the adits in order to obtain the data on the Lushan Ms7.0 strong earthquake.This paper researches the seismic response characteristics and topographic amplification effect from the monitoring points on the slopes.According to the Lushan main earthquake data recorded by the 7 seismic instruments on both banks of the valley,the horizontal component PGA of No.1 monitoring point on the right bank was 1.635 m/s2 and the vertical component PGA was 0.667 m/s2,obviously higher than PGA(0.110~0.424 m/s2) of the other monitoring points.By reference to the main shock records from the Guza strong earthquake monitoring station in Kangding,the PGA amplification factor of No.1 monitoring point reaches 6.9,and the Arias intensity enlarges several ten times.The horizontal to vertical spectral ratio shows that on the right bank of Lenzhuguan valley,the topographic amplification factor of the horizontal component from No.1 monitoring point reaches 9.0,the topographic amplification factor from No.2 monitoring point is 3.5,and the topographic amplification factors from No.4~No.7 monitoring points on the left bank are 1.0~3.0.The studies suggest that under a strong earthquake,the topographic amplification effect from ground shocks of thin ridges on the right bank of the Lenzhuguan valley is significantly stronger than that of the middle-high slopes on the left bank.And the convex topography from No.1 monitoring point is the maximum amplification.With the amplification of amplitude values,the strong vibration energy sharply increases in the effect of several ten times.When the accumulation of the vibration energy in a short period of time excesses or far excesses the strength of the rock mass,it is easy to form shatter,collapses,landslides and the projection effect of high and steep landforms.更多还原