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孤石对花岗岩残积土边坡稳定性影响的物理模拟实验分析

Physical Simulation Study on the Impact of Isolated Stones on the Stability of Granite Residual Soil Slopes

  • 摘要: 孤石的存在改变了降雨条件下花岗岩残积土边坡土体的应力分布和雨水入渗路径,进而对花岗岩残积土边坡的稳定性产生了较大的影响。为了深入理解孤石位置对边坡稳定性的影响机制,本文开展了降雨条件下孤石位置对花岗岩残积土边坡稳定性分析的物理模拟实验研究,旨在揭示不同孤石埋置位置对边坡动态失稳破坏过程的影响,并探讨了降雨和滑坡过程中土体孔隙水压力、土压力及含水率的动态演化规律,分析了边坡的动态失稳破坏过程。研究结果表明:(1)花岗岩残积土边坡失稳破坏过程为渐进性缓慢变形破坏,而非快速的、突然发生的整体破坏;(2)降雨过程中,土体的土压力、孔隙水压力和含水率变化曲线有一定的滞后效应;(3)孤石埋置位置对边坡稳定性有重大影响,当孤石位于边坡中部时,滑坡规模和剧烈程度大于孤石位于边坡深处和表层的情况;(4)雨水会在孤石处发生绕流,导致孤石周边土体孔隙比增大,形成利于雨水渗透的优势通道,促使坡体生成软弱滑裂面,从而造成边坡失稳。孤石埋设位置及深度是边坡软弱滑裂面形状及大小的主要影响因素。本研究的成果丰富了含孤石花岗岩残积土边坡失稳破坏的数据库,为强降雨条件下滑坡的预警分析提供了科学指导和理论依据,对提升滑坡灾害防治能力具有重要意义。

     

    Abstract: The presence of boulders alters the stress distribution and rainwater infiltration pathways within granite residual soil slopes under rainfall conditions, consequently exerting a significant influence on slope stability. To gain a deeper understanding of the influence mechanism of boulder position on slope stability, this study conducted physical simulation experiments investigating the effect of boulder position on the stability of granite residual soil slopes under rainfall. The research aims to elucidate the impact of different boulder burial positions on the dynamic instability failure process of slopes and explores the dynamic evolution patterns of soil pore water pressure, earth pressure, and moisture content during rainfall and landslide events. The dynamic instability failure process of the slope was analyzed. The results demonstrate that: (1) The instability failure process of granite residual soil slopes is characterized by progressive slow deformation, rather than a rapid, sudden catastrophic failure; (2) During rainfall, the response curves of soil earth pressure, pore water pressure, and moisture content exhibit a certain degree of hysteresis; (3) The burial position of the boulder critically affects slope stability; specifically, when the boulder is located in the middle section of the slope, the scale and severity of the landslide are greater than when the boulder is situated deeper within the slope or near the surface; (4) Rainfall runoff circumvents the boulder, leading to an increase in the void ratio of the surrounding soil. This creates preferential flow channels conducive to rainwater infiltration, promoting the formation of weak slip surfaces within the slope body, ultimately resulting in slope instability. The position and depth of the boulder are primary factors governing the shape and size of the weak slip surface within the slope. The findings of this study enrich the database concerning instability failure mechanisms of granite residual soil slopes containing boulders, provide scientific guidance and a theoretical basis for early warning analysis of landslides under heavy rainfall conditions, and hold significant importance for enhancing landslide disaster prevention and mitigation capabilities.

     

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