陕西泾阳南塬蒋刘4#滑坡运动堆积特征及流动性成因分析

自1976年引水灌溉以来,泾阳南塬黄土滑坡频发。2016年3月6日发生的蒋刘4~#滑坡呈近流体状高速远程运动,并呈长带状堆积于前缘平坦地面。其独特的运动堆积特征与该区其他类型滑坡差异显著,具有一定的特殊性。本文基于野外地质调查,通过无人机航测、现场含水率试验以及室内试验等手段,对蒋刘4~#滑坡进行分析研究。结果表明:(1)滑坡呈高速远程运动、长带状堆积,堆积体天然密度表现出从斜坡坡脚至前缘陡坎先增大,越过陡坎后明显减小的趋势;(2)滑源区黄土以粉粒为主、黏粒含量较少的粒组成分以及黄土中次生矿物含量较高是蒋刘4~#滑坡形成的物质基础;(3)大面积灌溉以及引水渠漏失严重造成大量水体下渗,该区S5古土壤层形成的相对不透水底板为上层滞水聚集创造了条件,使近底板上覆黄土处于饱水状态,导致斜坡稳定性降低;(4)地貌上剪出口位置较高,滑体潜在势能大,坡脚人工开挖的多级陡坎为滑坡高速远程运动创造了有利条件。蒋刘4~#滑坡规模较小但流动性显著,作为近年来蒋刘一带滑坡发展演化的主要类型,研究其运动堆积特征及流动性成因,为科学防治滑坡具有一定指导意义。

Analysis of Propagation and Deposit Characteristics and Liquidity of Jiangliu 4# Landslide in southern Jingyang Plateau, Shaanxi Province

The loess landslide occurred frequently in the south Jingyang plateau surface because of the irrigation science 1976. Jiangliu 4_# landslide happened on March 6, 2016, which moved nearly as fluid and accumulated as a long belt in the flat ground, was a typical high-speed and long-runout landslide. This landslide has significant differences with other types of landslides in research area because of the particular propagation and deposit characteristics. On the basis of field geological investigation, and through the low-altitude photogrammetry of the unmanned aerial vehicle, compactness and moisture content test on site and some lab experiments to study the Jiangliu 4_# landslide. The study found that: (1)The landslide moved with a high speed and unexpected long runnot and accumulated as a long belt, the deposits density increases from the slope toe to front scarp, after over the scarp decreases obviously; (2)The particle size composition of source area mainly composed of silty with less content of clay, is the material basis of the formation of landslides ; (3)Large area irrigation and aqueducts leaking seriously cause a large number of water infiltrated, the relatively impermeable floor formed by the S5 ancient layer has create conditions for the upper perched water gathered and make the loess stay at saturated state, which reduces the stability of slope.(4) On the landscape because the shear outlet of landslide is high and the landslide has a big potential energy, the artificial excavation multistage platform have created favorable conditions for landslide to remote high-speed movement. Jiangliu 4_# landslide as the main type landslide in this area with the development of irrigation, study the propagation and deposit characteristics and the reason of liquidity for scientific prevention and control of landslide has certain guiding significance.