北京山区岩土混合质边坡变形破坏机理分析

Analysis of Deformation and Failure Mechanism of Rock-soil Mixed Slope in A Mountainous Region of Beijing

岩土混合质边坡是公路沿线常见的边坡类型,其特有的结构性质导致滑坡频发,带来重大的经济损失和人员伤亡.该文以密云区石城镇栗林山庄边坡为研究对象,在野外调查、勘察的基础上,借助于室内直剪试验、数值模拟和现场监测,分析不同含水量下残坡积土内聚力和内摩擦角变化规律,揭示降雨入渗条件下边坡的变形破坏机理,研究边坡治理后的稳定性.结果表明:栗林山庄滑坡为沿土-岩接触面的折线形滑移破坏,降雨入渗是造成滑坡的关键因素;滑坡发生的演化过程可细分为微裂隙发育、滑带演化形成、滑面扩展这3个阶段;治理后边坡位移明显减小,剪应变增量云图未见明显滑动带;削坡、护坡以及挡墙等综合治理技术可为北京地区公路高切坡防治提供技术支持.

Rock-soil mixed slope is a common type of slope along the highway.Its unique structural properties lead to frequent landslides,causing heavy economic losses and casualties.This article takes the slope of Lilin Mountain Villa in Shicheng Town,Miyun District as the research object.Based on field investigation and exploration,with the help of indoor direct shear test,numerical simulation and on-site monitoring,the cohesion and internal friction of residual slope soil under different water contents are analyzed.The deformation and failure mechanism of slope under the condition of rainfall infiltration is revealed and the stability of slope after treatment is studied.The results show that the Lilin Villa landslide is a broken-line sliding failure along the soil-rock interface,and rainfall infiltration is the key factor causing the landslide;the evolution process of the landslide can be subdivided into three stages:micro-fracture development,slip zone evolution and formation-slip surface.After treatment,the slope displacement field has good continuity,no obvious sliding zone is seen in the shear strain incremental cloud map,and the overall stability is good;comprehensive treatment technologies such as slope cutting,slope protection and retaining walls have played some roles,providing technical support for the prevention and control of high cut slopes in Beijing.