Amplification effect of soil sites on ground motion in Anning River valley and Qionghai Lake area

Thet effect of site soil on ground motion is one of the main issues about earthquake engineering research. Based on the acceleration time histories recorded at 6 stations in Anning River and Qionghai Lake area, the amplification effect of 5 soil stations is studied by using the traditional spectral ratio method. The results are as follows: (1) There is good correlation between the amplification on ground motion in these sites and the geological zone, and the amplification effect on ground motion is different in different geological zones. According to the amplification of the size, the descending sequence is Qionghai Lake Plain subregion (Ⅲ₃), Qionghai Lake and flood plain subregion (Ⅲ₂), Anning River Plain area (Ⅱ), piedmont alluvial subregion (Ⅰ₂) and Zhongshan bedrock subregion (Ⅰ₁). (2) The piedmont alluvial subregion has no amplification effect on the low-frequency component of ground motion but significant amplification effect on the high-frequency one. (3) The Anning River Plain area has amplification effect on both the low-and high-frequency components of ground motion, and the amplification effect on the high frequency is stronger than that on the low frequency. The amplification effects of three components are different, that is, the descending amplification in the low frequency is UD, NS and EW, and that in the high frequency is EW, NS and UD. (4) The Qionghai Lake flood plain subregion has significant amplification effect on both the low-and high-frequency components of ground motion, and the maximum factor of amplification is about 1 Hz, with small differences among the maximum factors. (5) The Qionghai Lake Plain subregion has amplification effect on both the low-and high-frequency components of ground motion, the amplification factor is large, and the distribution band of significant amplification is wide.