甘肃黑方台地区灌溉型黄土滑坡形成机理与运动学特征——以焦家崖头13号滑坡为例  

The formation mechanism and disaster mode of loess landslides induced by irrigation in Heifangtai,Gansu Province:A case study of the 13th landslide in Jiaojiayatou

作　　者：贾俊[1] 朱立峰[1] 胡炜[1] 

机构地区：[1]国土资源部黄土地质灾害重点实验室/中国地质调查局西安地质调查中心,陕西西安710054

出　　处：《地质通报》2013年第12期1968-1975,共8页Geological Bulletin of China

基　　金：国家科技支撑计划项目课题(编号:2012BAK10B02);中国地质调查局项目(编号:1212011014024)

摘　　要：甘肃黑方台地区常年农业灌溉导致塬边产生大量的黄土滑坡,灌溉水长期入渗引起灌区地下水位上升,因地下水作用造成水敏性黄土遇水乃至饱水后强度劣化,进而产生斜坡失稳,因黄土滑坡剪出口高悬于上缓下陡的坡体中部,其成灾模式呈现出高位剪出后高速滑动,并产生远程运移,波及范围大,致灾后果严重。以甘肃省永靖县黑方台焦家崖头滑坡为例,在现场调查和地下水动态监测的基础上,对灌溉型黄土滑坡塑流-拉裂形成机理进行分析,并运用离散元模拟方法,对地下水位上升过程中模型底部饱水黄土软弱层的形成、演化过程和滑坡运动学特征进行模拟研究。结果表明,随地下水位的上升,模型底部软弱层范围不断增大;孔隙水压力主要作用于滑坡底部软弱层饱水黄土;地下水位高程上升至标高1682m时,滑坡产生整体破坏。Due to long-term irrigation, dozens of loess landslides were triggered along the edges of Heifangtai plateau, Gansu Province. Long-term infiltration of irrigation water not only leads to the elevation of groundwater table but also results in the reduction of strength of water-sensitive loess a^er soaking, and thus loess landslides occur. As the shearing mouths of the loess landslides are usually situated in the middle of the slopes which are gentle on the top and steep at the bottom, the disaster modes show features of high elevation shearing failure and later high-speed sliding. The landslides usually have long run-out, which affect large areas and cause severe consequences. A landslide case in Jiaojiayatou of Heifangtai in Gansu Province was studied in this paper. Based on field investigation and groundwater in-situ monitoring, the authors analyzed the formation mechanism of the plastic flow-tension crack mode of irrigation-induced loess landslide. Discrete element method was used to investigate the formation and evolution process of weak saturated loess layer in the process of the rising of groundwater table. The results show that, with the rise of the groundwater table, areas of the weak layer at the bottom of the model continuously increase. The pore water pressures mainly act on the weak saturated loess at the bottom of the landslide. When the groundwater table rises to an elevation of 1682m, overall failure of landslide occurs.

关 键 词：黄土滑坡 灌溉 塑流-拉裂 形成机理 运动学特征 

分 类 号：P642.22[天文地球—工程地质学]