中文摘要：

2015年4月29日早上7点55分,甘肃省永靖县盐锅峡镇党川村发生了小规模黄土滑坡,约5×10~4m~3失稳的黄土从黄河Ⅳ级台塬黑方台冲向黄河Ⅱ级台塬。滑坡后仅3h,再次产生较大规模的黄土滑坡,约35×10~4m~3黄土泥流冲向下游,形成长约780m,宽100m的堆积体,最大的堆积厚度17m,在党川段是少有的灾难性的滑坡。本文在滑前位移监测和裂缝分布变形研究的基础上,结合详细地质调查、低空摄影测量、现场工程地质测绘、含水率实验等手段,对党川2~#滑坡的基本特征进行了分析,并形成滑坡发生及成灾原因初步认识。结果表明：（1）从时间上来看,党川2~#滑坡共发生2次滑动,根据滑动模式和堆积特征上分析,第Ⅰ次相对独立,第Ⅱ次分为3轮滑动,共4轮滑动;（2）第Ⅰ次滑动区域面积8396m~2,变形区域仅在台塬边较小范围内,滑前长期蠕动变形是第Ⅰ次滑动发生诱发因素;（3）第Ⅱ次滑动区域面积为27422m~2,地表裂缝较少,滑前裂缝无明显位移变形,底部黄土的液化对台塬黄土滑坡的运动起了非常重要的作用,该次滑动滑距长、破坏强,具有突发性;（4）党川段开始发生大规模静态液化型黄土滑坡,并以落水洞形成滑坡边界,这对其他区段早期识别和监测预警研究具有重要意义。

英文摘要：

A small scale of loess landslide occurred at Heifangtai in Dangchuan village of Yongjing county.Its occurrence is at 7：50 of April 29,201 5.The site is at the edge of the loess plateau.The instability of loess has a volume of 5×1 04 m3 .It runs from the forth terrace to the second terrace of the Yellow river.After 3 hours later, however,a large scale of mudstone occurred at this place.Its volume is of 3.5 ×1 05 m3 .The mudstone deposit is 780meters long,1 00meters wide and the largest thickness of deposit is 1 7meters.The landslide is one of the few catastrophic landslides.This paper examines the sliding displacement monitoring and the crack distribution.Such examinations are combined with site geological investigation, low-altitude photogrammetry, site engineering geological survey and site moisture content test.This paper analyses the basic characteristics of the landslide and thenbsp;formation and reasons of landslide by preliminary understanding.The results show that：（1 ）There are two sliding cases at Dangchuan 2#landslide from the time.There is only one sliding case time in first time sliding and three sliding cases in second times landslide from sliding mode and deposit characteristic.Dangchuan 2#landslide has four times sliding cases in all.（2）The area of the first sliding is 8396m2 .Deformation distribution area is only at the edge of plateau and is smaller compared with the sliding area.The long-term creep deformation at the bottom of loess is the inducing factors of the first time landslide.（3）The area of the second sliding is 27422m2 .There is rarely any crack at this part and the crack has no obvious deformation before the second times sliding.The liquefaction of the loess at the bottom of landslide plays a very important role in the second times sliding.The landslide has the characteristics such as sudden occurrence,movement long distance and destructive stronger. （4）The Dangchuan section begins to start mass type static liquefaction loess landslide and the boundary of landslide