刘伦杰, 富海鹰, 张迎宾, 等. 2020.考虑滑床摩擦弱化的大光包滑坡运动机制DDA数值模拟研究[ J].工程地质学报, 28(6): 1254-1265. doi: 10.13544/j.cnki.jeg.2019-307.
    引用本文: 刘伦杰, 富海鹰, 张迎宾, 等. 2020.考虑滑床摩擦弱化的大光包滑坡运动机制DDA数值模拟研究[ J].工程地质学报, 28(6): 1254-1265. doi: 10.13544/j.cnki.jeg.2019-307.
    Liu Lunjie, Fu Haiying, Zhang Yingbin, et al. 2020. DDA simulation of mobility of Daguangbao landslide with frictionally weakened sliding bed[J]. Journal of Engineering Geology, 28(6): 1254-1265. doi: 10.13544/j.cnki.jeg.2019-307.
    Citation: Liu Lunjie, Fu Haiying, Zhang Yingbin, et al. 2020. DDA simulation of mobility of Daguangbao landslide with frictionally weakened sliding bed[J]. Journal of Engineering Geology, 28(6): 1254-1265. doi: 10.13544/j.cnki.jeg.2019-307.

    考虑滑床摩擦弱化的大光包滑坡运动机制DDA数值模拟研究

    DDA SIMULATION OF MOBILITY OF DAGUANGBAO LANDSLIDE WITH FRICTIONALLY WEAKENED SLIDING BED

    • 摘要: 2008年汶川发生MS8.0级地震,此次地震触发了大约20万处滑坡,其中大光包滑坡是汶川地震触发的最大规模的滑坡,其复杂的高速远程运动机理引起了国内外学者的广泛关注。本文结合热分解及动态结晶将地震中断层间摩擦弱化机制(闪速加热导致热分解及粉末润滑)运用于大光包滑坡高速远程运动的模拟。本文通过修改非连续变形分析(DDA)程序中强度参数的输入方式,以基于速度变化的强度参数取代原DDA程序中的常数强度参数,进而实现了摩擦系数随接触两侧相对速度变化的动态调整。运用修改后的DDA对大光包滑坡的运动过程进行模拟。模拟结果表明滑床摩擦弱化是导致大光包滑坡高速远程运动特征的重要原因,修改后的DDA由于考虑了滑床摩擦弱化能够更加合理地模拟滑坡的高速远程运动特征,本文模拟的大光包滑坡在地震作用下失稳后,由于滑床摩擦弱化,更多的能量转化为动能,高速滑体掠过黄洞子沟后,爬上对面的平梁子,最终由于平梁子的“急刹车”作用,滑体停止运动。与修改前DDA相比,修改后的DDA对大光包滑坡运动过程和最终堆积形态的模拟结果与已有文献记载和野外调查结果相吻合。这也间接证明了大光包滑坡滑动过程中由于白云岩间摩擦闪速加热导致热分解及粉末润滑造成的摩擦系数降低,可能是造成大光包滑坡高速远程运动的重要原因。

       

      Abstract: Daguangbao landslide is the largest landslide triggered by Wenchuan earthquake. How did it reach high speed and long-runout?This question attracted wide attentions of scholars at home and abroad. This paper aims the explanation for the mechanism of high-speed and long-runout and adopts the velocity-depending frictional weakening of sliding bed due to thermal decomposition and dynamic crystallization. This paper modifies the input manner of the strength parameter in the Discontinuous deformation analysis(DDA)method. The constant strength parameter in original DDA is replaced by the velocity-depending strength parameter. The paper realizes the dynamic adjustment of the friction coefficient with the change of relative velocity between two blocks on a contact. The modified DDA is used to simulate the mobility of Daguangbao landslide. The results show that the mechanism of frictional weakening can be an important reason for the characteristic of high-speed and long-runout of Daguangbao landslide. Comparing to the original DDA,the mobility characteristics of high-speed and long-runout landslides can be simulated more reasonably by the modified DDA,where the frictional weakening of the sliding bed can be implemented. Daguangbao landslide was instable during the earthquake. Due to the frictional weakening of sliding bed,more energy was converted into kinetic energy. After the high-speed sliding mass crossing the Huangdongzi valley,the sliding mass was blocked by the opposite Pingliangzi slope,and then the sliding mass stopped. Comparing with the original DDA results,the modified DDA′s simulation is in good agreement with the result from post-earthquake field investigation. It also indirectly proves that the friction coefficient of Daguangbao landslide may be reduced due to the thermal decomposition and powder lubrication caused by friction flash heating between dolomites,which may be an important reason for the high-speed characteristics of Daguangbao landslide.

       

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