泾河下游黄土台塬区侵蚀诱发滑坡机理

泾河下游黄土台塬区侵蚀诱发的黄土滑坡不仅威胁当地居民的生命财产安全,而且引发严重的水土流失及文物损毁等问题。以该类黄土滑坡为研究对象,在详细地质调查的基础上,取唐家村L2滑坡坡脚原状黄土进行减围压三轴剪切(RTC)试验,研究了饱和黄土的应力、孔压、围压特征以及剪切速率对土体力学行为的影响。结果表明,RTC应力路径下围压率达到0.55时,土体会因偏应力增大而引起塑性剪切破坏;同时,该应力路径下的饱和黄土内摩擦角很小,仅为10.7°;RTC应力路径下的破坏面,十分接近K 0状态面,说明天然斜坡坡脚饱和黄土在小幅水平应力降低条件下易于发生破坏,从而诱发滑坡失稳。

Mechanism of Erosion Induced Landslide in Loess Plateau Area in the Lower Reaches of Jing River

Erosion-induced loess landslides in the loess plateau of the lower reaches of the Jing River not only threaten the safety of life and property of local residents, but also cause serious problems such as soil erosion and cultural relic damages.Based on the detailed geological survey and taking the group of loess landslide as the research object, we conducted the RTC stress path test on the original loess of L2 landslide in Tangjiacun. This paper studies the characteristics of stress, pore pressure, confining pressure and the shear rate on the mechanical behavior of saturated loess.The results show that the soil causes plastic shear failure due to the increase of the pore pressure, when the confining pressure ratio reaches 0.55 under RTC stress path. At the same time, the internal friction angle of saturated loess under this stress path is very small, only 10.7°, while the failure surface under the RTC stress path is extremely close to the K 0 state surface. This indicates that the saturated loess at the natural slope foot is prone to damage under the condition of small horizontal stress reduction, thus inducing landslide instability.