极震荷载下筑坝堆石料变形特性及特高堆石坝极限抗震能力研究

A series of extreme earthquakes have occurred in recent years, and the seismic performance of the ultra-high rockfill dam under extreme earthquakes increasingly received more and more social and the national attention. However, the complex behavior of rockfill material under both large dynamic strain level and irregular cyclic loading cannot be well reflected by the present dynamic analysis method, and the soften behavior cannot be properly captured by existing dynamic software with implicit solution method. It is hard to evaluate the ultimate aseismic capacity of the ultra-high rockfill dam within the present framework of dynamic analysis method. In the program, the dynamic characteristics and residual deformation under large strain amplitude loadings are first studied, and the equivalent viscous-elastic model and the residual strain empirical model will be modified to capture the behavior of rockfill material under large strain level. Meanwhile, the change rules of work hardening, stress dilatancy and particle breakage under irregular loading will be discussed and a three-dimensional multi-yield surface model for rockfill material will be proposed. Finally, the software system will be developed by incorporating explicit solution method, and applied to solve the scientific and technical problems in the safety evaluation of the ultimate aseismic capacity of the ultra-high rockfill dam.

近年来世界范围内强震频发，极端地震荷载下特高堆石坝的抗震性能越来越受到社会和国家的重视，然而目前高堆石坝动力分析方法在模拟大应变幅值、实际地震的不规则循环荷载及坝体破坏软化等方面还存在诸多问题，难以合理评价高堆石坝极限抗震能力。针对这些问题，本项目拟开展大应变循环幅值条件下堆石料变形特性的大型三轴试验研究，建立适用于微小-大应变幅值范围的等价粘弹性模型和残余变形模型；揭示不规则循环荷载下堆石料的硬化、剪胀和颗粒破碎规律，提出考虑不规则循环加载历史的堆石料弹塑性模型；发展显式求解的动力弹塑性软件系统，并应用于特高堆石坝抗震性能评价，解决特高堆石坝极限抗震能力评价涉及的科学问题和技术难题。

本项目阐明了大应变幅值循环荷载下筑坝堆石料的动力特性和残余变形发展规律，在此基础上提出了适用于微小~大应变范围的残余变形模型。开发集成了SBFEM的复杂形状单元、无网格界面模拟方法、离散元-有限元耦合模拟方法及高性能计算技术和效率优化方法，实现了基于显式求解的高堆石坝弹塑性动力分析软件系统。针对堆石坝开展了系统的工程实例分析，直观再现了面板坝的地震破坏演化规律，精准定位了薄弱区域，量化了抗震措施效果，建议了地震条件下高堆石坝震陷率、滑移量的极限抗震能力指标。研究成果可为高堆石坝的安全评价和结构优化设计提供技术支撑。