黑方台焦家4号黄土滑坡发育特征及滑动机理

20世纪60年代以来,大量的灌溉系统在黄土地区建设运营,解决了农业的干旱问题,但同时灌溉也诱发了大量的滑坡。其中,2015年1月28日20:00,甘肃省永靖县焦家村发生了一起中等规模的黄土滑坡,滑坡严重影响其下方309国道线和六盘峡水库的安全。采用对裂缝分布、水文地质的调查,结合低空摄影测量、精细工程地质测绘、室内三轴试验等研究方法,对焦家4号滑坡的基本特征进行了分析,对形成滑坡的成灾机理有了初步认识。结果表明:(1)滑坡发生前,后缘裂缝有明显的变形情况;(2)滑坡滑动距离为548.3 m,体积为15.35万m~3,面积为6.6万m~2;(3)饱和黄土应力应变模式表现为强烈的应变软化剪缩型,并具有一定的静态液化特性;(4)滑坡是饱和黄土层静态液化引起的。

Development characteristics and sliding mechanism of Jiaojia No.4 loess landslide at Heifangtai table-land in Gansu Province

Since the 1960s, a large number of irrigation systems have been constructed to solve the agricultural drought problems in the loess area. At the same time, the irrigation has induced a lot of loess landslides. At 20:00 on January 28, 2015, a medium-sized loess landslide occurred in Jiaojia Village, Heifangtai table-land, Yongjing County, Gansu Province, northwestern China. The landslide seriously affected the safety of No.309 national road and Liupanxia Reservoir that were below Jiaojia No.4 landslide. Based on the investigation of fracture distribution and hydrogeology, combined with research techniques such as low-altitude photogrammetry, high-accuracy engineering geological mapping and triaxial test, the basic characteristics of Jiaojia No.4 landslide were analyzed, and the formation mechanism of the landslide was preliminarily understood. The preliminary results showed that: ①Before the occurrence of the landslide, there are obvious deformations of trailing-edge fractures; ②The sliding distance of the loess landslide is 548.3m，the sliding volume is 15.35×104 m3 and the sliding area is 6.6×104 m2; ③ The stress-strain mode of saturated loess is characterized as strong strain softening and shear shrinkage, as well as a certain of static liquefaction; ④ The landslide is caused by static liquefaction of saturated loess layers.