基于InSAR技术的古滑坡复活早期识别方法研究——以大渡河流域为例

近年来,青藏高原东缘高山峡谷区古滑坡复活呈现活跃趋势,并造成重大灾害损失,因此古滑坡复活的早期识别成为地质灾害研究领域普遍关注的课题。本文以大渡河流域为例,在古滑坡发育特征调查分析的基础上,提出了基于InSAR技术的古滑坡复活早期识别的一般步骤:①分析古滑坡及周边主要SAR数据源及其适宜性,制定最优InSAR监测方案;②通过InSAR综合观测,获得高质量的长时间序列变形,筛选显著变形部位(特征点);③根据特征点的时序变形曲线,进行古滑坡复活的演化阶段判别和稳定性预测。基于斋藤原理,提出了古滑坡复活的三段式演化过程;结合PS-InSAR监测的累积位移-时间曲线,提出了将弹性变形与匀速变形之间的拐点作为古滑坡复活的起点标志,把匀速变形向加速变形转变的拐点作为复活失稳的标志,为高山峡谷区隐蔽型古滑坡复活的早期识别提供了新途径。

InSAR-based method for early recognition of ancient landslide reactivation in Dadu River,China

In recent years, the reactivation of ancient landslides has been in active situation and caused great losses in the high mountainous valley areas on the east margin of the Tibetan Plateau. Therefore, the early recognition of ancient landslide reactivation has become an important subject in geological hazard re-search. Taking the Dadu River as an example,on the basis of field investigation and analysis of the devel-oping characteristics of ancient landslides,the general steps of early recognizing the ancient landslide reacti-vation by InSAR technology have been put forward:(1) Analyze the data source and suitability of the main SAR data for the ancient landslides and their surrounding areas, and formulate the optimal InSAR monitor-ing scheme. (2)Through the comprehensive observation of InSAR technology, obtain the high-quality long-time displacement information,and select the significant deformation parts or typical points. (3) Accord-ing to the cumulative displacement-time curve of the typical monitoring points, carry out the evolution stage discrimination and stability prediction of the ancient landslides. On the basis of the Saito''s principle, the three-stage evolution process of the ancient landslide reactivation has been proposed. Combining with the accumulated displacement-time curve monitored by PS-InSAR, a new idea is stressed that the inflec-tion point between elastic deformation and uniform deformation is regarded as the starting point of ancient landslide reactivation and the inflection point from uniform deformation to accelerated deformation is regard-ed as the sign of failure. All above has provided a new way for the early recognition of the reactivation of the hidden ancient landslides in the high mountainous valley areas.