【摘要】 芦山MS7.0地震、鲁甸MS6.5地震诱发了大量的次生山地灾害,一些学者认为地形放大效应是其中的一个影响因素,但目前斜坡地震动响应研究仍然缺乏大量的实测数据支撑。通过在冷竹关两岸斜坡不同部位掘进平硐并放置强震监测仪器的方法,对沟谷两岸斜坡地震动响应特征进行研究,剖面较为完整地记录了康定地震两岸斜坡的地震动响应特征。监测数据揭示,(1)相对于康定姑咱参考站,位于右岸"半岛状"凸出山梁顶部1#监测点的水平和竖直向PGA放大系数分别达到了10.6~11.5、7.1,阿里亚斯强度最大,水平东西向比竖直向HVSR频比值达到11.1,卓越周期在低频部分;位于右岸山梁中部2#监测点水平和竖直向PGA放大系数分别达到了4.3~5.0、2.3;(2)左岸地形坡面起伏较小,记录的峰值加速度较小,仅在坡折部位5#监测点有明显的放大,水平与垂直峰值加速度放大系数分别为3.0~4.5、2.3,各监测点频比存在多个卓越周期,其放大效应在高频段更突出;(3)近直线型斜坡内(6#及7#监测点)放大效应相对较弱,且监测洞外侧放大系数大于水平深度较大的内侧。结果表明冷竹关两岸斜坡存在明显的地形放大效应,且右岸"半岛状"凸出山脊地形较左岸中高山斜坡地形放大效应显著。对比芦山地震该剖面放大系数,揭示了背坡面效应。更多还原

【Abstract】 Many secondary natural geological disasters are caused by Lushan MS7. 0 and Ludian MS6. 3earthquake. Some scholars consider the disasters may be associated with topographic amplification effect of seismic waves. But it is still lack of a large number of slope seismic response data to verify such hypothesis. The strong monitoring site of Luding Lengzhuguan is located on both sides of the Lengzhuguan valley,a tributary of the Dadu River and situated to the right back of the river. Tunnels excavated in different parts of the slope are used to place earthquake monitoring instruments on both sides of the valley. The instruments monitored the Kangding MS6. 3earthquake on November 22,2014 in Sichuan,China. The earthquake monitoring data show the follows:( 1)Reference to Kangding Guzan strong earthquake monitoring station of the main shock records( its horizontal and vertical PGA components are 16. 4 and 15. 7gal,respectively),the horizontal and vertical PGA amplification factorsof the 1#monitoring site on the top of the peninsular terrain on the right bank reach 10. 6- 11. 5 and 7. 1,respectively. The Arias Intensity of the 1#monitoring site is largest. The Predominant Period was concentrated in the low-frequency,and horizontal to vertical spectral ratio reaches 11. 1. The horizontal and vertical PGA amplification factors of the 2#monitoring site in the middle reach 4. 3-5. 0 and 2. 3,respectively. Both of the Arias Intensity and horizontal to vertical spectral ratio were smaller than those at 1#.( 2) The slope terrain variation on the left bank is small and the record of PGA is low. the result at the 5#monitoring site is enlarged obviously. The horizontal and vertical PGA amplification factors are 2. 1- 4. 5 and 1. 7- 2. 3,respectively. The monitoring sites on the left bank have several Predominant Period. The amplification effect is more prominent at high-frequency. The Arias Intensity of each is smaller than the right monitoring sites.( 3) Ground motion topographic amplification effect in the nearly linear slope part is weak( 6#and 7#).Some monitoring sites are narrowed to varying degrees. The amplification factor of the outside monitoring site is larger than the level depth of the inside monitoring site. Studies suggest that ground motion topographic amplification effect is obvious on both sides of the Lengzhuguan valley. The topography amplification effect of the peninsular terrain on the right bank is stronger than that on the left nearly linear slope.Furthermore,the amplification factor on the top of the peninsular terrain on the right bank is bigger than that on the middle. The topography amplification effect on the part of slope break is obvious and the part of nearly linear slope is weaker. According to direction of seismic wave propagation,the Lengzhuguan monitoring station is at the back side for Kangding earthquake. It is contrary for Lushan earthquake. Comparison of the results between the seismic data of Kangding earthquake and Lushan earthquake,it is found that the PGA amplification coefficients of each monitoring site during Kangding earthquake is bigger than those at Lushan earthquake. One result reaches to 5times.更多还原