地下水诱发渐进后退式黄土滑坡成因机理研究——以甘肃黑方台灌溉型黄土滑坡为例

MECHANISM OF GRADUAL RETREAT LOESS LANDSLIDE CAUSED BY GROUNDWATER: A CASE STUDY OF THE IRRIGATION LOESS LANDSLIDE IN HEIFANGTAI,GANSU PROVINCE

黑方台位于我国甘肃省永靖县,该区由于长期灌溉导致地下水位上升,诱发了大量的黄土滑坡,其中最典型的一类滑坡为渐进后退式黄土滑坡。通过对比代表性滑坡多期Google影像,并结合现场调查分析了近年来新发生的滑坡,发现该类黄土滑坡具有典型的渐进后退式演化过程。现场调查和对典型滑坡剖面黄土含水率的实测发现,黄土层底部受地下水的长期浸泡软化所形成的软基效应是使黄土滑坡不断发生的主要原因,而滑坡发生后留下的弧形凹槽往往成为地下水局部集中汇聚和排泄点,滑源区被滑坡残留体覆盖导致地下水位局部雍高上涨,将导致同一滑坡发生多次渐进后退式破坏。

Heifangtai is located in Yongjing County,Gansu province. The loess landslide is very developed due to irrigation. One of the most typical landslides is the gradual retreat of the loess landslide caused by long- term irrigation. This paper compares the Google images and the field survey of representative landslide occurred in recent years. It shows that the loess landslides have the characteristics of gradual recession. It further investigates and analyze the water content of the loess landslide profile. It finds that the main reason for loess landslide occurred continuously are soft base effect formed by long-term soaking of groundwater. The arc groove of the landslide often becomes the concentration of groundwater and drainage points. The residual landslide accumulation in slide source area rises the local underground water. It is the main reason to make the same position more and more gradual retreat type landslide.