李均益,罗永红,周赞,南凯. 2024. 青川刨地里地震滑坡发育特征及其成因机制探讨. 地震学报,46(3):1−12. doi: 10.11939/jass.20230058
引用本文: 李均益,罗永红,周赞,南凯. 2024. 青川刨地里地震滑坡发育特征及其成因机制探讨. 地震学报,46(3):1−12. doi: 10.11939/jass.20230058
Li J Y,Luo Y H,Zhou Z,Nan K. 2024. Analysis of characteristics and failure mechanism of Paodili seismic landslide in Qingchuan County. Acta Seismologica Sinica46(3):1−12. doi: 10.11939/jass.20230058
Citation: Li J Y,Luo Y H,Zhou Z,Nan K. 2024. Analysis of characteristics and failure mechanism of Paodili seismic landslide in Qingchuan County. Acta Seismologica Sinica46(3):1−12. doi: 10.11939/jass.20230058

青川刨地里地震滑坡发育特征及其成因机制探讨

Analysis of characteristics and failure mechanism of Paodili seismic landslide in Qingchuan County

  • 摘要: 以“5.12”汶川地震诱发的青川县刨地里滑坡为例,现场调查了滑坡的地质特征,并基于离散元软件(UDEC)分析了1号滑坡动力响应及变形破坏过程,探讨了滑坡的成因机制。现场调查表明,刨地里1号斜坡具有近水平“上硬下软”的地层结构,其中石坎断层通过了斜坡后缘;滑坡堆积体的岩性分带特征表明,刨地里1号滑坡下部千枚岩先于上部硅质岩被破坏,且破坏时间早于2号和3号滑坡;数值模拟研究揭示,峰值加速度放大效应在断层带附近的千枚岩内最强,其放大系数达6.79,导致下层千枚岩首先沿陡倾面产生拉裂破坏,随后上层硅质岩体产生拉裂破坏,结果与现场调查堆积物特征较吻合;断层和上硬下软的地层结构对刨地里滑坡动力响应、变形及破坏起到了控制作用。该研究可为上硬下软且含断层的地震滑坡的评价提供参考。

     

    Abstract: The problem of slope stability in high-intensity mountainous area is prominent. It is of great significance to study the relationship between geological structure and strata structure and the triggering mechanism of landslide under earthquake action. In this paper, the geological characteristics of the landslide in Qingchuan County are investigated, and the dynamic response and deformation and failure process of 1st landslide are analyzed based on discrete element software (UDEC). The field investigation shows that the slope of Paodili 1st has a near-horizontal “upper-hard, lower-soft” stratigraphic structure, in which faults pass through the back edge of the slope. The lithologic zonation of landslide deposits shows that the lower phyllite of Paodili 1st was destroyed earlier than the upper siliceous rock, and the broken time was earlier than 2nd and 3rd. The numerical simulation study reveals that the peak acceleration amplification effect is strongest in phyllite near the fault zone, with an amplification factor of 6.79. This leads to the lower phyllite first experiencing tensile failure along the steep dip surface, then the upper siliceous rock mass produced tension failure. The results are in good agreement with the characteristics of the deposits in the field investigation. The dynamic response, deformation, and failure of the landslide are controlled by the fault and the hard and soft strata structure. This study can provide a reference for seismic landslides evaluation in regions characterized by faulting and “upper-hard, lower-soft” strata.

     

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