延安北连接线黄土滑坡变形机制地质分析与模型试验研究

Geological analysis and model test study on the deformation mechanism of loess landslide in the North connection line of Yan'an

以延安北连接线黄土滑坡为例,通过现场实地地质调查、地质分析以及模型试验的方法对滑坡的孕育、发展变形机制进行分析,其中模型试验分不同阶段开挖、注水的方式来模拟现实情况的路基开挖及降雨工况。通过各工况综合分析以及工况单独影响权重分析,得到如下结论;(1)由坡脚开挖以及降雨综合影响的滑坡变形机制可大体归纳为:原始地貌-开挖卸荷-卸荷裂缝-降雨及地表水入渗-土体抗剪强度降低-土体软化形成滑带-坡体滑塌;(2)坡脚开挖为坡体致滑的潜在影响因素,坡体开挖形成的临空面高度对坡体稳定性起到一定的影响作用;(3)水是致使坡体发生滑动的直接影响因素,具有时间累积效应,因此,无论是对原边坡的工程扰动还是人为填方形成的具有潜在危险性的边坡,修建引排水系统显得尤为重要。

Taking the landslide of the North connection line of Yan’an as an example,through field geological survey,geological analysis and model test,the deformation mechanism of the landslide is analyzed.During the model test,different excavation stages and water injection were carried out to simulate the subgrade excavation and rainfall conditions.Through the comprehensive analysis of various working conditions,the deformation mechanism of the landslide resulted from slope toe excavation and rainfall can be determined.The mechanism and process are original landforms,unloading due to excavation,cracks generation,rainfall and surface water infiltration,reducing of the shear strength of the loess,forming slide zone due to the loess softening,slope collapse.The excavation of the slope toe is an influence factor of the landslide.The height of the surface resulted from the slope excavation has an effect on the slope’s stability.Water is the direct reason for the landslide,which has the effect of time accumulation.Therefore,it is very important to structure the drainage system for landslide prevention.