南天山大龙池堰塞体形成演化过程分析

Analysis of the formation and evolution process of the Dalongchi landslide dam in the South Tianshan Mountains

堰塞体是高山峡谷区开展工程建设重点关注的地质体,本研究以南天山大龙池堰塞体为研究对象,探索南天山高山峡谷地区堰塞体的成因及演化过程。基于大龙池区域卫星遥感影像、区域地质资料,依托现场调查和地质钻探等方法,结合理论计算与有限元-离散元模拟技术,对南天山高山峡谷地区堰塞体的成因及演化过程进行了系统研究。结果表明:(1)大龙池堰塞体北侧山体陡峭,山体表面可见多处滑坡擦痕和刻槽,堰塞体堆积结构具有明显的反粒序和拼图结构特征,提出了大龙池堰塞体为高速远程古滑坡堆积的成因机理;(2)通过复原大龙池北面山体滑坡原始坡面,对其运动学特征进行理论计算与数值仿真模拟,结果表明大龙池北侧山体曾发生高速远程滑坡;(3)大龙池堰塞体的形成演化过程可分为古滑坡孕育、古滑坡堵河形成堰塞体以及堰塞体溃决3个阶段。研究结论可为南天山地区类似堰塞体的成因分析提供参考。

[Objective]Landslide dams are a geological body of key concern for engineering construction in alpine canyon areas.This paper takes the Dalongchi landslide dam in the South Tianshan Mountains as the research object to explore the origin and evolution process of the landslide dam in alpine canyon areas of the South Tianshan Mountains.[Methods]Based on satellite remote sensing images,regional data,field investigation,and geological drilling data in the Dalongchi region,combined with theoretical calculations and finite element discrete element simulations,this paper systematically delved into the deposit characteristics and the formation and evolution process of the Dalongchi damming body.[Results]The results show that(1)Many landslide scratches and grooves can be seen on the steep mountain surface on the North side of the Dalongchi damming body,of which the packing structure has obvious inverse grading features and a jigsaw structure,and it is speculated that the formation may be caused by the accumulation of the high-speed and long-distance ancient landslide of Dalongchi.(2)By conducting the recurrence of the northern original surface of the Dalongchi landslide and theoretical calculation and numerical simulation on its kinematic characteristics,the results were then induced that there was a high-speed and long-distance landslide on the north side of the mountain that led to the formation of the damming body of Dalongchi.(3)The formation and evolutionary phases of the Dalongchi damming body can be divided into the embryonic stage of ancient landslides,the river-blocking forming stage of the damming stage by ancient landslides,and the overlapping stage of ancient damming bodies.[Conclusion]The study of the formation and evolution of the Dalongchi dammingbody can provide a reference for the subsequent genetic analysis of similar studies in the southern Tianshan region.