怒江四线钢桁拱桥岸坡稳定性勘察及评价

Investigation and Evaluation of Bank Slope Stability of Nujiang Four-Line Rigid Truss Arch Bridge

怒江四线刚桁拱特大桥工程地质条件复杂,桥址区岸坡陡峻,其稳定性对桥梁设计影响较大。通过综合地质勘察,查明了怒江大桥两岸的边坡岩土结构及岩土体物理力学性质;并通过数值模拟计算,分析天然状态下边坡开挖及边坡开挖耦合暴雨工况下桥址区岸坡的变形及稳定性,结果表明:(1)在天然工况下,预计受开挖影响的C12K左岸等子滑坡表现稳定;(2)暴雨工况下,两岸边坡应力和位移变化不大,主要表现为断层及破碎岩体带附近的应力集中以及在坡体开挖附近出现位移变形;(3)暴雨工况下稳定性系数出现一定下降,但仍处于稳定状态。通过现场施工验证对比,总结了特殊结构桥梁地质勘察工作经验,对类似案例有一定借鉴意义。

The engineering geological conditions of Nujiang four-line rigid truss arch bridge are complex,and the bank slope of the bridge site is steep,and its stability greatly impacts the bridge design.Through comprehensive geological survey,the geotechnical structure and physical and mechanical properties of the slopes on both sides of Nujiang river bridge are found out.Through numerical simulation calculation,the deformation and stability of the bank slope at the bridge site under the natural state slope excavation and slope excavation and rainstorm conditions are analyzed,and the following conclusions are mainly drawn:(1)Under the natural condition,the C12K left bank landslide affected by excavation is expected to be stable;(2)Under the rainstorm condition,the stress and displacement of the slopes on both banks have little change,which is mainly manifested by the stress concentration near the fault and broken rock mass zone and the displacement deformation near the slope excavation;(3)Under rainstorm condition,the stability coefficient decreases to a certain extent,but it is still in a stable state.Through on-site construction verification and comparison,the experience of geological survey for bridges with special structures is summarized,which can be used for reference in similar cases.