深切峡谷区公路桥梁段斜坡崩滑灾害风险评估

Risk assessment of slope failure hazards near bridges of a highway across deep canyons

深切峡谷区边坡高陡,崩滑灾害风险防控对峡谷山区桥梁安全至关重要。针对峡谷山区桥梁斜坡崩滑灾害风险问题,给出了地质灾害易发程度分析、危险性分析、易损性评估、风险等级评定和防治可行性评价各阶段的判别指标和方法。依据边坡岩土体稳定性定量评价指标进行易发程度判别;针对不同运动特征灾害体,采用灾害体规模、运动速度及冲击能量等进行危险等级评定;通过结构力学分析评价构造物易损性,根据受损程度和灾害损失评定桥梁段斜坡崩滑灾害风险等级;根据防治工程实施难度和可靠性评价防治可行性。该方法应用于雅康高速公路泸定大渡河特大桥,根据评估结果选用了风险最低的桥位,采用抗滑桩、锚索等对重点区域系统加固,并结合碎屑流拦截结构,实现对选用桥位边坡地质灾害的防治。

Risk prevention and control of high cutting slope in deep canyon area is critical to bridge safety. The discriminate indexes and analyzing method of geological hazards in different stage are given,including the susceptibility analysis, hazard analysis, vulnerability assessment, risk rating evaluation and feasibility evaluation. According to the quantitative evaluation indexes of slope stability to assess the susceptibility of geohazards. The degree of hazard is classified according to the scale,speed and impact energy of the hazard.The structural vulnerability is evaluated based on structural mechanics analysis. The risk rating of geological hazard is evaluated according to the damage degree and disaster loss. Then the feasibility of prevention and control are determined by the difficulty and reliability of prevention and control. This method was applied to the large span bridge acrossing Dadu River in Luding on the expressway from Ya’an to Kangding,the position with lowest risk was selected according to the evaluation results. Anti-slide piles combined with anchor cables were used to reinforce the key area,the debris flow interception structure was adopted to prevent and control the geological hazards on bridge site slope.