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刘新荣, 许彬, 刘永权, 王继文, 蔺广义. 频发微小地震下顺层岩质边坡累积损伤及稳定性分析[J]. 岩土工程学报, 2020, 42(4): 632-641. DOI: 10.11779/CJGE202004005
引用本文: 刘新荣, 许彬, 刘永权, 王继文, 蔺广义. 频发微小地震下顺层岩质边坡累积损伤及稳定性分析[J]. 岩土工程学报, 2020, 42(4): 632-641. DOI: 10.11779/CJGE202004005
LIU Xin-rong, XU Bin, LIU Yong-quan, WANG Ji-wen, LIN Guang-yi. Cumulative damage and stability analysis of bedding rock slope under frequent microseisms[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(4): 632-641. DOI: 10.11779/CJGE202004005
Citation: LIU Xin-rong, XU Bin, LIU Yong-quan, WANG Ji-wen, LIN Guang-yi. Cumulative damage and stability analysis of bedding rock slope under frequent microseisms[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(4): 632-641. DOI: 10.11779/CJGE202004005

频发微小地震下顺层岩质边坡累积损伤及稳定性分析

Cumulative damage and stability analysis of bedding rock slope under frequent microseisms

  • 摘要: 三峡库区蓄水后诱发的高频度微小地震对边坡稳定性产生了重大影响。采用振动台模型试验和UDEC离散元数值计算方法,深入地探究了库区典型顺倾层状岩质边坡在高频次微小地震下的累积损伤和稳定性。研究表明:①地震持续作用下,边坡自振频率、阻尼比、损伤度和损伤速率依次降低、增大、累积变大和不断提升,各测点PGA响应表现为“高程效应”和“趋表效应”,且PGA放大系数均呈降低趋势;②高、低动荷载振幅阶段边坡岩体非线性累积损伤模型可分别用指数函数和三次函数描述,其演化曲线分别呈初期轻微降低、中期线性递增、后期平缓微增的“S”型特征和急速增长的“陡升”型特征;③边坡累积损伤–失稳破坏呈现为起伏体爬坡–啃断–磨平、次级节理(层面)起裂–扩展–贯通、坡体沿复合破坏面发生整体滑移、失稳破坏后岩体以破碎–大型–巨型块状堆积于坡脚,且含起伏体边坡整体稳定性更优;④动荷载振幅、动荷载频率、坡高、坡角增大而层面厚度减小时,边坡临界失稳微震作用次数减小、累积永久位移增大、稳定性系数减小,且层面出露边坡更易发生失稳破坏。

     

    Abstract: Micro-seism frequently occurs in the Three Gorges Reservoir after impoundment and has a significant impact on slope stability. To investigate the cumulative damage and stability of typical bedding rock slope under frequent microseisms, the shaking table model tests and UDEC discrete element numerical analyses are conducted. The results indicate that: (1) The damping ratio, damage degree and damage rate of slope increase with the increase of seismic duration, while the natural frequency and PGA amplification coefficient decrease. The PGA response of slope shows "elevation effect" and "surface effect". (2) The non-linear cumulative damage model under high and low seismic amplitudes can be represented by exponential and cubic functions respectively, and the evolution curve shows "S" characteristics of slight decline in initial stage, linear increase in intermediate stage and gentle increase in later stage, and "steep" characteristics of rapid rise. (3) The gradual process of cumulative damage and instability is as follows: undulant body climbs, shear and grinds, cracks initiate, propagate and run through, the slope slips wholly along the composite sliding surface, and rock mass accumulates at the slope foot in the form of broken, large and giant blocks. The stability of slope with undulant body is better. (4) The critical times of microseism decrease and the cumulative permanent displacement increases with the increase of seismic amplitude, frequency, slope height and slope angle and the decrease of bedding thickness, and accordingly the stability factor decreases. The slope with outcropped bedding is more prone to fail.

     

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