考虑持时的高沥青混凝土心墙坝抗震性能评价

现行水工抗震设计规范中关于强震特性中的幅值和频谱均有明确规定，而强震持时特性对高性能水工结构地震反应的影响至今尚未被纳入规范中。目前衡量强震持时特性的定义方式较多，但多数情况下仅考虑单方向地震动持续时间，低估了多方向强震持时特性对高性能水工结构地震反应的影响。鉴于上述原因，本文以西部大石门高沥青混凝土心墙砂砾石坝为例，建立“大坝-宏观库水-坝基”动态耦合分析系统，基于能够考虑多方向强震持时特性的综合持时指标，通过增量动力分析（IDA）法探究短持时和长持时地震对高沥青混凝土心墙砂砾石坝抗震性能的影响。采用坝顶相对震陷率作为抗震性能的评价指标，给出了高沥青混凝土心墙砂砾石坝的性能水平划分等级，得到了考虑地震动综合持时特性的大坝地震易损性概率曲线。结果表明：地震动综合持时特性对大坝不同性能水平的破坏概率影响显著；当地震动强度相同时，长持时地震动作用下大坝的破坏概率均大于短持时地震动作用。

Seismic performance evaluation of high asphaltic-concrete-core rockfill dams considering duration effect

The current hydraulic seismic design code has clear provisions for the amplitude and frequency spectrum of strong earthquakes, but no provision for the impact of their duration on the seismic response of high-performance hydraulic structures. At present, a variety of definitions for the duration characteristics of strong earthquakes are available, but most of them only consider unidirectional ground motions, underestimating the duration impact in multi-directional cases. This paper constructs a dam-reservoir-foundation dynamic coupling analysis system through a case study of a high asphalt-concrete-core sandy gravel dam. We adopt an integrated duration index for multi-directional strong earthquakes, and use an incremental dynamic analysis (IDA) method to evaluate the influence of short-duration and long-duration ground motions on the seismic performance of high asphaltic concrete core rockfill dams, taking the relative settlement ratio of dam crest as an evaluation index of structural performance. Thus, this analysis system can give the damage level of a high asphaltic-concrete-core rockfill dam and its seismic fragility curves considering the integrated duration effect. Results show that the integrated duration characteristics of ground motions have a significant impact on dam failure probability at different performance levels. For fixed seismic intensity, dam failure probability at longer ground motion duration is greater than that at shorter duration.