水平软弱夹层黄土滑坡形成机制及启动角度

人工坡脚开挖引发不少滑坡地质灾害，当含有水平软弱夹层时将会进一步加快坡体失稳。为了研究具有此类地层结构黄土边坡在坡脚开挖后变形破坏形成机制和失稳破坏启动角度，以山西省吕梁市临县“5?3”大型黄土滑坡为研究对象，采用现场调查、理论分析和数值模拟等手段展开研究。研究结果表明，实际滑坡主要由坡脚工程开挖导致关键阻滑块体缺失所引发，坡体沿近乎水平软弱卵石夹层滑动破坏；具有水平软弱夹层地层条件的黄土滑坡形成机制主要表现为：（1）水平软弱夹层应力集中，（2）牵引沉陷后缘拉裂，（3）裂缝滑面贯通失稳破坏。该类地层结构黄土边坡坡脚开挖失稳破坏启动角度介于35°~40°，数值模拟结果与实际滑坡案例结果一致。研究结论为类似地层结构黄土边坡的防治提供基础理论。

Formation Mechanism and Starting Angle of Loess Landslide with Horizontal Weak Interlayer

The excavation of artificial slope toe causes many landslide geological disasters. When there is horizontal weak interlayer, the slope instability will be further accelerated. In order to study the formation mechanism of deformation and failure and the starting angle of instability and failure of loess slope with such stratum structure after slope toe excavation, the "5.3" large loess landslide in Linxian County, Luliang City, Shanxi Province was studied by means of field investigation, theoretical analysis and numerical simulation. The results show that the actual landslide is mainly caused by the lack of key resistance blocks caused by slope toe engineering excavation, and the slope slides along the nearly horizontal soft pebble interlayer; The formation mechanism of loess landslide with horizontal weak interlayer formation conditions is mainly as follows: (1) stress concentration of horizontal weak interlayer, (2) tensile crack at the trailing edge of traction settlement, and (3) penetration and instability failure of fracture sliding surface. The starting angle of excavation instability and failure of this kind of stratum structure loess slope toe is between 35 ° ~ 40 °. The numerical simulation results are consistent with the actual landslide case results. The research conclusion provides a basic theory for the prevention and control of loess slope with similar stratum structure.