大渡河河谷摩岗岭地区为地震高发区,采用FLAC3D软件对该地区三维地质模型进行模拟计算,结合3个监测点的实测数据,研究了该地区不同坡体地震动的响应.结果表明:以海拔最低的3号监测点为参考,河流右岸1号监测点水平SN向地表峰值加速度(PGA)的放大系数达到最大值4.43,数值模拟值为3.50;河流左岸5号监测点地震波的放大系数较右岸明显偏低,实测PGA放大系数2.94,数值模拟结果为1.54.同时数值模拟得出河流右岸坡体随着高程的增加PGA不断增大,在山脊顶部达到最大;而在河流左岸,PGA遵循先增大后减小的规律.研究表明,该地区不同坡体形态对地震动响应也不同,大渡河右岸单薄山脊对地震波放大效应明显高于左岸浑厚山体.%In order to investigate the seismic wave amplification effect of different slope body in the area of Mogangling ridge, Dadu River canyon,FLAC3D software was used to simulate the 3D model of the mountain ridge,and the results were compared with measured data at three monitoring points. The results indicated that with No. 3 monitoring point at the lowest elevation as the reference,the horizontal peak ground acceleration (PGA) amplification coefficient at No.1 monitoring point is the biggest,with the measured value of 4.43 and the simulated values of 3.5;on the left bank of the river,the seismic wave amplification coeffi-cient was lower than the right bank,the measured PGA amplification coefficients at No.5 monitoring point was 2.94 and the nu-merical simulation results was 1.54. The simulation results show that the PGA increases with the increase of elevation and rea-ches the maximum at the top of the ridge on the right bank of the river;on the left bank slope of the river,PGA follows the regu-lar pattern of increasing first and then gradually decreasing. The studies suggest that the responses of different slope shapes to the ground motion are different,the seismic response of thin ridge on the right bank is significantly higher than that of the left deep slope.
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