汶川8.0级地震触发崩滑灾害机制及其地质力学模式

MECHANISM AND GEOMECHANICAL MODES OF LANDSLIDE HAZARDS TRIGGERED BY WENCHUAN 8.0 EARTHQUAKE

汶川8.0级地震由于地震震级高、持续时间长、震区地形地质环境复杂,因而所触发的崩塌、滑坡不仅数量巨大,而且成因机制也极为复杂,具有与通常重力环境下斜坡失稳机制迥异的特征,许多现象非常特殊并超越了人们过去的认识。通过现场调查,发现强震触发崩滑灾害具有以下特殊的动力过程,即独特的震动溃裂现象,特殊的溃滑失稳机制,超强的动力特性和大规模的高速抛射与远程运动,大量山体震裂松动等。为此,定义了若干新的词语,如震裂、溃滑、溃崩、抛射等来描述这些独特的动力过程,并在此基础上,结合具体斜坡结构,提出了对汶川地震触发崩塌、滑坡成因机制的分类体系,这一体系包括五大类、14种类型。重点分析了一些典型类型斜坡失稳的发生过程,地质力学机制及相应的"概念模型",尤其是与大型滑坡发生最为密切的溃滑型滑坡的发生过程及动力机制,初步较为系统的揭示了汶川8.0级地震触发地质灾害的成因机制、地质模式和动力特征。

Due to the extremely high magnitude, long duration of vibration and the complicated geo-environment in disastrous area, the Wenchuan 8.0 earthquake produces not only a huge number of landslides and rockfalls, but also a series of complicated dynamic processes involved in their occurrence, such as very common loosing and cracking of mountains, unique shattering-sliding, extremely powerful dynamic process of large-scale or individual rock block ejection, long distance motion etc.. They are quite different from the characteristics of landslides and rockfalls under general gravity force, and present knowledge is very limit in this field. In order to describe above-mentioned special dynamic processes of shattering-cracking, the shattering-sliding, shattering-falls and ejection are defined. Combining with the slope structures, a mechanism classification system of strong earthquake-triggered landslide and rockfall are suggested, which includes 5 categories and 14 types. In addition, the basic characteristics, dynamic processes and geomechanical conceptual models of some typical types are analyzed, especially the type of shattering-sliding for most large-scales landslides is involved. The formation mechanism, geomechanical models and dynamic features of landslides and rockfalls triggered by Wenchuan 8.0 earthquake are revealed.