沥青混凝土心墙堆石坝地震变形评价方法及其可靠度分析

沥青混凝土心墙堆石坝可就地取材,工程造价低,在我国西部强震区被广泛应用。因其工作条件复杂,且筑坝材料具有非线性特性,故其地震安全评价问题一直受到工程界的关注。因此开展地震作用下沥青混凝土心墙堆石坝的可靠度分析具有理论意义和工程应用价值。本文以坝体裂缝作为坝体地震变形破坏的判断依据,将坝体地震变形倾度作为地震安全的控制指标,建立了基于倾度法和中心点法的沥青混凝土心墙堆石坝地震变形可靠度分析方法。以某98 m高的沥青混凝土心墙堆石坝为例,进行了地震变形的可靠度分析。结果表明:基于本文沥青混凝土心墙堆石坝地震变形可靠度分析方法,获得的大坝设计基准期内的年计地震变形失效概率py=2.156×10^-6,对应的可靠指标β=4.6,满足规范要求;采用倾度法和中心点法相结合,可以考虑坝体材料分区的影响,获得较为准确的土石坝地震变形失效概率结果,对土石坝具有普遍适用性。本文提出的土石坝坝体地震变形可靠度分析方法,可为沥青混凝土心墙堆石坝抗震设计、地震风险分析以及风险等级的建立提供依据。

Dam seismic deformation evaluation method of asphalt concrete core rockfill dam and its reliability analysis

Asphalt concrete core rockfill dam are widely used in the meizoseismal area of Western China because of the merits such as using local materials and low construction cost. Due to its complicated work-ing conditions and the non-linear characteristics of dam building materials, the issue of seismic safety as-sessment has always attracted the attention of engineering circles. The research on reliability analysis of as-phalt concrete core rockfill dam under earthquake has theoretical significance and engineering application value. In this paper, dam cracks are used as the basis for judging dam seismic deformation failure, and dam seismic inclination is used as seismic safety index. A seismic deformation reliability analysis method for asphalt concrete core rockfill dams was established on the basis of the inclination method and the cen-ter point method. The proposed method is employed to calculate the seismic failure probability of a certain 98m-high asphalt concrete core rockfill dam. The results show that the seismic deformation annualized fail-ure probability of the dam is 2.156×10^-6, and the corresponding reliability index is 4.6. The result meets the standard requirements. The inclination method and the center point method were used to obtain accu-rate seismic deformation failure probability of earth-rock dams without being affected by dam material sub-zone, which has universal applicability for earth-rock dams. The seismic deformation reliability analysis method proposed in this paper can provide reference for seismic design, risk analysis and establishment of risk level of asphalt concrete core rockfill dam.