Seismic dynamic response characteristics of the lower soft and upper hard mountain slopes in Gongxian, Sichuan

Abstract

The coseismic collapse of lower soft and upper hard slopes develops during strong earthquakes. To reveal the response characteristics of such slopes under dynamic loads, a strong-earthquake monitor was installed in Wutong Village, Gongxian County, to collect the slope surface and the ground motion with respect to different lithologies, and two earthquakes with different azimuths and epicentral distances were also recorded. Research shows that: ①The response law of ground motion has strong directivity and distance. The two earthquakes are in different directions and distances from the monitoring station, making the peak acceleration and Arias intensity of the Ms 4.0 earthquake smaller than those of the Ms 3.2 earthquake. ②The 0-30 Hz seismic wave has an amplification effect near the high and steep open surface of the lowland mountains. The main frequency of monitoring point No.1 is lower than that of monitoring points No.3 and No.5, and the main frequency of monitoring point No.3 is the highest. The amplitude range of point No.5 is 0.018-0.055 m/s-2, while the amplitude range of point No.3 is 0.036-0.087 m/s-2. Compared with point No.5, point No.3 has the highest three-way amplitude magnified by 1.58-2.0 times year-on-year. ③The dominant frequency of argillaceous sandstone is 4.8-8.4 Hz, and the dominant frequency of limestone is 5.5-21.4. Different rock formations have different resonance frequencies. The frequency-selective amplification effect of limestone on seismic waves is stronger than that of argillaceous sandstone. ④Seismic waves have a selective amplification effect on mountain slopes with different elevations. The larger the elevation within a certain range, the more obvious the terrain amplification effect is.

Keywords

• gongxian earthquake
• slope seismic dynamic response
• seismic directional effect
• amplification effect
• mountain slope