基于应力分析的黄土层内滑坡地震失稳机制

摘要

In view of the disaster -prone and destructive characteristics of the seismic landslide in the loess layer in the Loess Plateau,three typical landslides are investigated,and the characteristics of instability and failure of this kind of landslide are obtained.By further considering the stress characteristics and shear failure type of soil in different parts of the slope,and introducing the earthquake effect in the form of stress,the shear failure types and shear stress variation law under the change of stress state of soil in different parts of such landslide are analyzed during its instability.Thus the seismic instability mechanism of such landslides with a feature of top soil occurs ten-sion shearing damage led by reduction of minor principal stress first,followed by inclined surface soil occurs com-pression shearing damage led by increase of principal stress,and loess seismic subsidence reduce friction and speed slip is proposed based on stress analysis,and then the reinforcement and protective measures are put forward corre-spondingly.%针对黄土高原地区黄土层内地震滑坡灾害易发多发和破坏性强的特点，选取三处典型滑坡进行考察，得出了此类滑坡的失稳破坏特征。进一步结合斜坡不同部位土体的受力特点和剪切破坏形式，将地震作用以应力形式引入，分析得到了该类滑坡发生时不同部位土体的剪切破坏形式及应力状态变化下剪应力的变化规律。从而基于应力分析给出了具有坡顶土体首先发生小主应力减小主导的拉张型剪切破坏，坡面土体随后发生大主应力增加主导的压剪型剪切破坏，黄土震陷降低滑面摩擦阻力加速滑体滑移特点的黄土层内滑坡地震失稳机制，进而针对此类滑坡地震失稳机制提出了相应的加固及防护措施。