基于地震动信号分析的滑坡堵江过程研究——以白格滑坡堰塞湖为例

Study on landslide blocking process based on ground motion signals analysis:case of Baige landslide dammed lake

为精准识别滑坡堰塞湖灾害过程的动态信息进而重构其致灾过程,以2018年两次白格滑坡堰塞湖为例,基于周围测震台站记录的地震动信号,采用Hilbert-Huang变换方法分析不同频段的地震动信号特征,结合现场调查资料,对白格滑坡和堰塞坝溃决运动特征进行分析,还原了较为完整的滑坡堰塞湖致灾过程。结果表明:第一次白格滑坡发生在10月10日22:05:41,持续112 s,第二次滑坡发生在11月3日17:21:15,持续102 s;两次滑坡激发的地震动信号以低频为主(0.008~0.060 Hz),均先出现低频信号且幅值逐渐增大,随后伴随强烈高频信号的产生并迅速增大到峰值再缓慢降低到噪声水平。两次滑坡的运动过程均分为3个阶段:高位滑坡连续滑落阶段/滑坡启动阶段、滑体破碎解体阶段、散落堆积阶段。两次堰塞坝溃决的过程均可分为4个阶段:过流孕育阶段、侵蚀阶段、溃口加速扩展阶段、水沙再平衡阶段。研究成果可为滑坡堰塞湖灾害链的精准识别和灾后救援工作提供参考,也可为滑坡堰塞湖灾害动力特征参数反演提供基础。

To accurately identify the dynamic information of the landslide barrier lake disaster process and reconstruct its disaster causing process,two landslide barrier lake disasters in 2018 were studied based on the seismic signals recorded by the around seismograph stations.The Hilbert-Huang transform method was adopted to analyze the frequency characteristics of the recorded seismic signals.Combining with the field investigation data,the process of river blocking and dam breaching were analyzed,and the disaster process was revealed in this study.The results showed that the first Baige landslide occurred at 22:05:41 on October 10th and lasted for a total of 112 s.The second landslide occurred at 17:21:15 on November 3rd and lasted for a total of 102s.The seismic signals induced by the two Baige landslides were mainly low-frequency signals(0.008~0.06 Hz).The low frequency components first appeared and the amplitude gradually increased,followed by strong high-frequency components,which rapidly increased to the peak value and then slowly decreased the noise level.The landslide processes of two landslides could be divided into three stages:the continuous sliding stage of the high landslide(the starting stage),the crushing and disintegration stage,and the scattering and accumulation stage.The process of two dam breachings could be divided into four stages:the initial stage of overtopping,the erosion stage,the accelerated expansion stage and the water and sand rebalancing stage.This study can provide a reference for accurate identification of landslide barrier lake disaster chain and post-disaster rescuing,it can provide a basis for the inversion of dynamic characteristic parameters of landslide barrier lake disaster.