甘肃舟曲河那滑坡变形特征及孕灾机理

Disaster Mechanism and Stability Evaluation of Hena Landslide in Zhouqu,Gansu Province

针对2018年7月甘肃省舟曲县武坪乡发生的河那滑坡,结合地质资料、卫星遥感影像以及现场调查资料等多源手段,为了探明滑坡滑动范围、发生特征以及赋存环境;通过钻探和井探结合取样的方式,在室内和现场开展相关试验,厘定滑坡区的地层特性、滑带及滑体的岩土力学性质及特征,并对滑坡孕灾机理进行深入研究。结果表明:河那滑坡为堆积层推移式滑坡,具有多级、多层、长距离的变形特点;滑坡滑面(带)主要为土质滑带,该滑带是现状滑动变形的主导。归结了滑坡堆积层孕灾机理。首先,受频繁地震的影响,滑坡堆积体中上部变形产生较多裂缝,岩土体强度劣化,坡体开始产生蠕动;其次,在短期强降雨作用下,水岩作用使得裂缝进一步扩张,造成内部岩土体加速软化,形成软弱夹层,蠕动变形加剧;最终,坡体滑动。河那滑坡具有明显应力-渗流-损伤共同作用的特点,是典型的震后降雨致灾滑坡。可见,河那滑坡的复活是多重因素在特定时空顺序作用下发生的具有复杂变形特征的多级滑坡。

In view of the Hena landslide occurred in Wuping Township,Zhouqu County,Gansu Province in July 2018,the sliding range,occurrence characteristics and occurrence environment of the landslide were explored by combining multi-source means such as geological data,satellite remote sensing images and field investigation data.Indoor and field tests were carried out to determine the formation characteristics of the landslide area,the rock and soil mechanical properties and characteristics of the sliding zone and the sliding body by means of drilling and well exploration.The results show that Hena landslide is a progressive landslide with multi-stage,multi-layer and long-distance deformation characteristics.The sliding surface(zone)of landslide is mainly soil sliding zone,which is the dominant factor of current sliding deformation.The disaster mechanism of landslide accumulation layer can be summarized as follows:firstly,due to the influence of frequent earthquakes,the upper and middle deformation of landslide accumulation body produces more cracks,the strength of rock and soil deteriorates,and the slope begins to creep.Secondly,under the action of short-term heavy rainfall,the water-rock interaction makes the cracks further expand,resulting in accelerated softening of internal rock and soil mass,forming a weak interlayer,and aggravating creep deformation.Finally,the slope slides.Hena landslide has the characteristics of obvious stress-seepage-damage interaction,which is a typical post-earthquake rainfall-induced landslide.It can be seen that the resurrection of Hena landslide is a multi-stage landslide with complex deformation characteristics under the action of multiple factors of a specific space-time sequence.