重庆武隆鸡尾山岩质滑坡软弱带微观特征

Micro-characteristics of weak-soft zone of Jiweishan Rockslide in Wulong County,Chongqing,June 5,2009

滑带是滑坡研究的重要内容之一,滑坡软弱带的类型、微观结构特征、物质组分和物理力学性质等决定了滑带的应力状态和强度的变化,这些变化与滑坡活动密切相关。在对鸡尾山滑带野外宏观地质调查的基础上,通过一系列手段对该滑坡滑带软弱面特征进行了较详细的分析。显微结构测试结果表明,软弱带为条纹状含钙质灰质板岩,不规则粒状或团粒状之序的多种矿物穿插共生。采用理学DMAX-3C衍射仪(CuKa,Ni滤光)分析显示,方解石含量高达68%、有机质为13%、滑石9%、蒙脱石5%、石英4%、白云石1%。扫描电镜(SEM)观察软弱带饱水前后结构特征,显示水会导致软弱带微裂缝的形成,可能成为连续滑动拉裂的主要通道。结合野外调查结果,软弱带的几种微观结构对于促使该滑坡在漫长的时间滑坡周界形成—软弱面蠕滑—应力集中、剪出崩塌—解体冲击—灾难形成的前慢后快演变的链式灾变过程中起到了重要的作用,也较好地诠释了滑坡滑动的一些基本事实。

Study on the slip zone is an important part of landslide work.The type,microscopic structure,material composition,physical and mechanical behavior and etc.of the slip zone determine the changes in its stress state and strength,which are closely related with the activities of a landslide.Based on the macroscopic geologic survey on the slip zone of the Jiweishan landslide happened in Wulong,Chongqing,June 5,2009,series of means have been taken to do the detailed analysis on the weak zone characteristics.The result of microstructure test shows,the weak zone composes of calcareous slate and has intergrowth with many kinds of irregular granular or agglomerate granular minerals in the form of thrust.The result by DMAX-3C diffractometer（light filtering by CuKa,Ni）shows,the content of calcite reaches up to 68%,as well as the organic matter 13%,talcum 9%,montmorillonite 5%,quartz 4% and dolomite 1%.Using scanning electron microscope（SEM）to observe the change of weak zone before and after saturation,the result shows that water can cause the micro cracks forming the main channel of continuous slip tension.Combining the field survey results,some micro structures above the weak zone play a great important part in the chain-styled catastrophe process with a rapid after former slow development,during which several stages have been experienced：the formation of landslide boundary in a long period→creep along the weak surface→stress concentration and then shear collapse→disintegration impact→catastrophe occurrence,and also verify and interpret the basic facts of landslide movements.