唐涛,王运生,吴昊宸,刘世成,冯卓,詹明斌. 2024. 冷竹关沟高陡斜坡地震动响应特征分析. 地震学报,46(3):1−12. doi: 10.11939/jass.20220121
引用本文: 唐涛,王运生,吴昊宸,刘世成,冯卓,詹明斌. 2024. 冷竹关沟高陡斜坡地震动响应特征分析. 地震学报,46(3):1−12. doi: 10.11939/jass.20220121
Tang T,Wang Y S,Wu H C,Liu S C,Feng Z,Zhan M B. 2024. Analysis of seismic response characteristics of Lengzhuguan high and steep slope. Acta Seismologica Sinica46(3):1−12. doi: 10.11939/jass.20220121
Citation: Tang T,Wang Y S,Wu H C,Liu S C,Feng Z,Zhan M B. 2024. Analysis of seismic response characteristics of Lengzhuguan high and steep slope. Acta Seismologica Sinica46(3):1−12. doi: 10.11939/jass.20220121

冷竹关沟高陡斜坡地震动响应特征分析

Analysis of seismic response characteristics of Lengzhuguan high and steep slope

  • 摘要: 四川省泸定县冷竹关沟两岸属于高陡斜坡,距2022年5月20日汉源MS4.8地震震中52 km。基于冷竹关沟监测剖面上安置的4台强震仪对汉源MS4.8地震的监测数据,研究高陡斜坡上的地震波响应规律,并与前人研究成果对比分析,结果显示:① 斜坡对此次地震的地震波放大效应在水平南北向最为显著,同时在右岸半岛状山梁处的放大作用强于左岸浑厚山体,并且呈现随着高程增加而增大的趋势;② 斜坡右岸强震的卓越频率为2—6 Hz,左岸卓越频率主要分布在7—13 Hz为主,冷竹关沟高陡斜坡的地震波卓越频率在半岛状山梁部位以特低频为主,在浑厚山体斜坡以中值低频为主,在未来可能发生的地震中,斜坡与卓越频率在此范围内的地震波更容易发生共振作用,造成坡体地震动响应强烈;③ 冷竹关沟高陡斜坡存在地震波背坡效应,同时该处斜坡对地震波的放大效应还受到微地形的控制,地震波在右岸坡顶凸起地形处能量最为强烈,右岸斜坡坡顶在地震波经过时更容易发生崩塌等次生灾害。

     

    Abstract: 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 strong earthquake mountainous area. Both sides of Lengzhuguan Gully in Luding 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 located 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 Longmen Mountain Fault Zone intersects with the Xianshui River Fault Zone, The tectonic activity in the area is strong, and setting up strong earthquake monitoring profiles here can effectively monitor seismic wave information in the nearby area. These seismic data can effectively analyze the seismic dynamic characteristics of the terrain in the area. On May 20, 2022, an MS4.8 earthquake occurred in Hanyuan County, Sichuan Province, with the epicenter 52 km away from the Lengzhuguangou monitoring profile. This earthquake triggered the installation of four strong seismic instruments on the Lengzhuguangou 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 analyzed through the time history curve data of monitoring points, Obtain the peak acceleration amplification coefficient and Arias intensity amplification coefficient of different elevation monitoring points. By analyzing the response spectrum characteristics of acceleration under different damping ratios of 5%, 10%, and 20%, obtain the site response law and seismic period, and use wavelet transform to obtain the time-frequency domain information of seismic waves. Study the terrain amplification effect of seismic waves in different parts of the slope, And compared and analyzed with previous research results based on the Kangding MS6.3 earthquake and Lushan MS7.0 earthquake monitoring data in Lengzhuguan Gully, the seismic response characteristics on both sides of Lengzhuguan Gully were revealed. The results showed that: ① The high and steep slope of Lengzhuguan Gully had a clear directional amplification effect on the seismic wave of the Hanyuan MS4.8 earthquake, which was 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 increase of elevation; ② Comparing the Kangding MS6.3 earthquake and the Lushan MS7.0 earthquake, it can be seen that the dominant frequency of the strong earthquake on the right bank of Lengzhuguangou 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. In future earthquakes, the high and steep slope of Lengzhuguangou is more likely to resonate with seismic waves with dominant frequencies within this range, resulting in a strong seismic response of the slope. The lower the excellent frequency of high and steep slopes, the stronger the amplification effect; ③ Compared 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.

     

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