晋西黄土崩塌类型及其变形-破坏机制

Types of loess collapse and its deformation-failure mechanism in western Shanxi Province

晋西黄土高原沟壑纵横的地貌形态使得黄土崩塌灾害频发,加之因其纵向贯穿砂黄土带、典型黄土带和黏黄土带,黄土崩塌类型齐全,为黄土崩塌成因及分类理论研究提供了便利条件。基于此通过开展大量野外调查研究,提出了晋西黄土崩塌的“主控因素分类”和“变形-破坏方式分类”,并探索了滑落式黄土崩塌与黄土滑坡的界定条件。结果表明:晋西黄土崩塌按主控因素可分为冻融破坏、构造应力诱导、降雨诱发、灌溉诱发、工程扰动、植物根劈、复合型等7种类型,按变形-破坏方式可分为被动(拉裂)倾倒式、主动(推挤)倾倒式、下挫式、坠落式、被动(拉裂)滑落式、主动(剪切)滑落式、剥落式等7种类型;将变形黄土体重心的垂直移动距离大于其水平位移距离2倍以上且其致灾模式以“击毁+掩埋”为主,“冲毁”为辅的认定为滑落式崩塌。以上研究结果不仅可用于指导晋西黄土高原崩塌灾害防治规划工作实践,亦可为黄土崩塌理论研究提供可以借鉴的理论基础。

The vertical and horizontal landform of the Loess Plateau in western Shanxi Province has led to frequent occurrence of loess collapse disasters.In addition,due to its longitudinal penetration through the sand loess zone,typical loess zone,and clay loess zone,the types of loess collapse are complete,providing convenient conditions for the study of the causes and classification theory of loess collapse.Based on this,the“classification of main control factors”and“classification of deformation-failure modes”of loess collapse in western Shanxi were put forward through a large number of field investigations,and the boundary conditions of sliding loess collapse and loess landslide were explored.The results indicate that the loess collapse in western Shanxi Province can be divided into seven types according to the main control factors:freeze-thaw failure,tectonic stress induction,rainfall induction,irrigation induction,engineering disturbance,plant root splitting,and composite type.According to the deformation-failure mode,the loess collapse in western Shanxi Province can be divided into seven types:passive(tensile fracture)toppling collapse,active(push)toppling collapse,plunge collapse,fall collapse,passive(tensile fracture)pull-down collapse,active(shear)slide collapse,and spalling collapse.If the vertical movement distance of the center of gravity of the deformed loess body is more than twice its horizontal displacement distance,and its disaster causing mode is mainly“destruction+burial”,supplemented by“erosion”,then it is considered as a sliding collapse.The above research results can not only be used to guide the practice of prevention and control planning for collapse disasters in the Loess Plateau of western Shanxi Province,but also provide a theoretical basis for reference for the theoretical research of loess collapse.