ISSN 1000-3665 CN 11-2202/P

    1965年烂泥沟滑坡前兆、高速远程运动及后期演化特征

    Precursors and Motion Characteristics of the 1965 Lannigou Rockslides and the Subsequent Evolution

    • 摘要: 烂泥沟滑坡是我国最著名的巨型高速远程滑坡之一。1965年烂泥沟滑坡活动造成近百年来最严重的单体滑坡灾害。此后,1991年和2007年滑坡又经历2次较大规模活动。然而,对于1965年烂泥沟滑坡前兆和2个序次活动的成生关系、此后滑坡活动特征,尚无定论;对滑坡现今状态尚不清楚。本文基于多时相、多源遥感卫星影像及近期无人机测量和现场调查数据,对上述问题进行了分析。研究发现,1965年滑坡前,滑源区北侧山体表开裂明显;1965年11月22日、23日2次滑动为北、南两侧山体分别滑动;其成生关系是:北侧山体沿倾向坡外结构面高位剪出,高速冲向南侧山坡,受其冲击,南侧山体次日沿倾向坡外结构面高位、高速滑出,第一序次滑动规模远大于第二序次;高速运动的部分滑坡碎屑流从流通区北侧山坡飞跃通过、且铲刮冲击强烈,滑坡碎屑流最远运动至烂泥沟与普福河交汇处向东2.8 km;1991年滑坡滑源区紧邻1965年北侧滑坡滑源区的西侧边界,滑坡碎屑流终止于沟道中段;2007年滑坡滑源区位于1991年滑坡滑源区上部,滑坡碎屑流运动距离略小于1991滑坡碎屑流。目前,滑源区西北侧、西南侧山坡上地表开裂明显,西北侧山坡上其中一条裂缝扩展速率约16.7 m/a,西南侧山坡上裂缝扩展迹象不明显。因此,西北侧山坡显示再次滑动之势,须引起关注。

       

      Abstract: The Lannigou rockslide is one of the most well-known giant and rapid rockslides with long runout in China. The 1965 Lannigou rockslides caused the most catastrophic consequence in China since 1920’s, and were followed by two more rockslides in 1991 and 2007, respectively. However, it remains unclear that how precursors of the 1965 rockslides were and relationship between the two movement sequences was, so did the following activities in 1991 and 2007. Those unclear questions were explored in this paper based on 23 remote sensing satellite images taken during the period between 1965 and 2020 and the UAV image taken in 2019 as well as field survey then. It is found that: 1) tension cracks could be seen on the northern slope of the source area before the 1965 rockslides, evidencing the precursors there, 2) the 1965 rockslide first occurred on the northern slope, and subsequently induced the rockslide on the southern slope next day resulted from its strong impact, 3) rapid granular flows of the two rockslides jumped and flew over the northern slope of the transition zone, and scrapped, entrained surficial layer there, 4) the granular flow did not reach the Jingsha River, but ended ca. 2.8 km east of the intersection between the Lannigou and the Pufu river; 5) the source area of the 1991 rockslide just neighbored the northwestern boundary of the 1965 rockslide on the northern slope, while the 2007 rockslide neighbored the upper boundary of the 1991 rockslide, and 6) the detached volumes and runouts of the 1965, 1991 and 2007 rockslides showed a decrease order. Recently, tension cracks can be clearly seen on both the northwestern and southwestern slopes. One of tension cracks on the northwestern slope is extending with a rate of 16.7 m/a, while those on the southwestern slope has shown no sign of extension since 2014, indicating that the northwestern slope may fail again. It is thus that an attention should be paid to the northwestern slope via monitoring its deformation and keeping local people away from the area likely affected.

       

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