多级旋转黄土滑坡基本类型及特征分析

多级旋转黄土滑坡因其分布密集、继发性强、滑体结构难以区分而成为我国黄土高原最为复杂的滑坡灾害类型。本文在引入多级旋转滑坡的定义的基础上,通过野外详细调查和工程勘察等手段,研究我国黄土高原地区典型的多级旋转黄土滑坡的基本类型、特征和成因。提出了金台型多级旋转黄土滑坡和黑方台型多级旋转黄土滑坡2种滑坡模式和滑坡结构特征,其中,金台型多级旋转黄土滑坡主要包括超深层的旋转-平移型滑坡和深层旋转滑坡2种类型,滑体由近水平层状厚层黄土、高阶地砾石层和上新世的红色砂质硬黏土层组成,多属于大型滑坡; 黑方台型多级旋转黄土滑坡主要包括中浅层旋转黄土层内滑坡和顺层多级旋转黄土-泥岩滑坡2种类型。同时分析这类滑坡主要诱发因素:新构造运动、河流的侧蚀、地层结构、灌溉以及季节性冻融作用,其中地下水的作用是目前最主要诱发因素。本文分析为该类滑坡成因机理进一步研究奠定基础。

BASIC TYPES AND CHARACTERISTICS OF MULTIPLE ROTATIONAL LANDSLIDES IN LOESS

Due to concentrated distribution,strong secondary and complex structure,multiple rotational landslides in loess is one of the most complicated landslide hazard types in the loess plateau.At first,this paper gives a definition of multiple rotational landslides in loess.So,it further studies the typical basic types,the characteristics and causes of multiple rotational landslides in the loess plateau of China in terms of hazards survey,geotechnical investigation and survey.Two types of multiple rotational loess landslides are the type of Jintai and the type of Heifangtai.They have different failure mechanisms and structures.The Jintai type of the landslides includes two classes of deep-seated multiple rotational-translational landslide and deep-seated multiple rotational landslide.The Heifangtai type of the landslides has mainly two classes of middle-shallow rotational loess landslides and multiple rotational bedding loess-mudstone landslides.The Jintai landslides are mostly large-scale landslides,composed by the three strata: near-horizontal thick layer pleistocene loess,gravel layer upper pleistocene terrace and pliocene red-hard clay.The analysis indicates that triggers of multiple rotational loess landslides include neotectonic movement,lateral erosion,strata lithology and structure,irrigation and seasonally freezing and thawing.Among the triggers,groundwater is the most inducing factor.The paper lays the foundation for mechanism study of multiple rotational loess landslides.