高拱坝安全度计算方法对比分析

Comparative Analysis on Calculation Methods of Safety Degree for High Arch Dam

超载法、强度储备法和综合法是目前用有限元法分析拱坝整体安全度时采用的主要方法,失稳判据主要有塑性区贯通判据、位移突变判据和屈服体积比突变判据等,分析计算时选择哪种破坏模拟方式和失稳判据目前没有统一的认识。结合工程实例,分析比较了3种计算方法及3种失稳判据的特点。分析结果表明,超载法和强度储备法计算得到的拱坝破坏模式不同;综合法的计算结果与选择的超载、降强的组合形式有关;塑性区贯通判据尚无一个客观指标,受人为因素影响较大;位移突变判据与失稳控制点的选择关系密切;屈服体积比突变判据以坝体及坝基系统的屈服体积为考察对象,受局部材料的强度和结构影响较小。

The overload method, strength reserve method and synthetical tools are main tools for evaluating the overall safety degree of arch dam by FEM, and corresponding instability criterions mainly include plastic zone transfixion criterion, displacement catastrophe criterion and yield volume ratio catastrophe criterion. The understandings in choosing damage simulation method and instability criterion are no uniform at present. Combining with actual engineering eases, the characteristics of above three calculation methods and three instability criterions are compared. The results show that, （a） the overload method and strength reserve method can conclude different failure mode of aeh dam, （b） the calculate result of synthetical method is effeeted by the combination form of overload and strength decline, （c） the plastic zone transfixion criterion has no objective index yet, which is largely influenced by human factors, （d） the displacement catastrophe criterion is closely related to the choose of instability control point, and （e） the yield volume ratio catastrophe criterion is slightly effeeted by the strength and structure of local materials as it takes the yield volume of dam body and its foundation system as a study object.