Analysis of seismic response characteristics of high and steep slope in Lengzhuguan gully
The northwest region of Sichuan is located in the southeastern part of the Qinghai Tibet Plateau,with well-developed mountain and canyon landforms and frequent earthquakes.It belongs to a seismically active mountainous region.Both sides of Lengzhuguan gully in Lud-ing County,Sichuan Province belong to high and steep slopes,which are representative in the high mountain and canyon areas of western China.At the same time,Lengzhuguan gully is loc-ated in the transitional zone from the Qinghai Tibet Plateau to the Sichuan Basin,as well as the"Y"shaped area where the southwest end of the Longmenshan Fault Zone intersects with the Xianshui River Fault Zone,The tectonic activity in the area is strong,and the setting up strong earthquake monitoring profiles here can effectively monitor seismic wave information in the nearby area.These seismic data can be used to effectively analyze the seismic dynamic charac-teristics of the terrain in the area.On May 20,2022,an MS4.8 earthquake occurred in Hany-uan County,Sichuan Province,with the epicenter 52 km away from the Lengzhuguan gully monitoring profile.This earthquake triggered the installation of four strong seismic instruments on the Lengzhuguan gully monitoring profile,and obtained seismic wave time history data of the Hanyuan MS4.8 earthquake.To study the seismic wave response law on high and steep slopes,the peak acceleration and Arias intensity characteristics of this seismic wave were ana-lyzed through the time history curve of monitoring points,Obtain the peak acceleration ampli-fication coefficient and Arias intensity amplification coefficient of different elevation monitor-ing points.After processing and analyzing the acceleration time-history curve(including filter-ing and correction),we have calculated the three-component seismic acceleration response spectra under different damping ratios(5%,10%,20%).Studying the terrain amplification ef-fect of seismic waves in different parts of the slope,and comparing and analyzing with previ-ous research results based on the Kangding MS6.3 earthquake and Lushan MS7.0 earthquake monitoring data in Lengzhuguan gully,we revealed that the seismic response characteristics on both sides of Lengzhuguan gully.The results showed that:①The high and steep slope of Lengzhuguan gully had a clear directional amplification effect on the seismic wave of the Hany-uan MS4.8 earthquake,which was the most significant in the horizontal north-south direction.At the same time,the amplification effect at the peninsula shaped mountain ridge on the right bank was stronger than that on the thick mountain body on the left bank,and it shows a trend of increasing with the elevation increasement;②Comparing the Kangding MS6.3 earthquake and the Lushan MS7.0 earthquake,we can see that the predominant frequency of ground motion on the right bank of Lengzhuguan gully is 2-6 Hz,and the dominant frequency on the left bank is 7-13 Hz.This indicates that the dominant frequency of seismic waves on this slope is mainly at ultra-low frequencies in the peninsula shaped mountain ridge,and at median low frequencies in the thick mountain slope.For the possible earthquake in the future,the high and steep slope of Lengzhuguan gully is more likely to resonate with seismic waves that having dominant frequen-cies mentioned above,which may result in a strong seismic response of the slope.The lower the characteristic frequency of high and steep slopes,the stronger the amplification effect;③Compared with the seismic monitoring data of Kangding MS6.3,it indicates the existence of the back slope effect of seismic waves.At the same time,the amplification effect of the slope on seismic waves is also controlled by the microtopography.The seismic waves converge at monitoring point 1,and the seismic energy is the strongest.This indicates that the right bank slope top is more prone to seismic response and secondary disasters such as landslides under the influence of the protruding aerial terrain at the top of the mountain ridge.
Hanyuan MS4.8 earthquakeLengzhuguan gullyamplification effectground motion of slopedeep canyon
万方数据
维普
