混凝土重力坝极限抗震能力评价方法

Study on ultimate aseismic capacity evaluation of concrete gravity dam

从基于性能的抗震设防标准及理论出发,针对混凝土重力坝的结构特点,在结构地震反应时域分析的基础上,提出从大坝需求能力比与超应力累积持时、破坏模式、抗滑稳定性及坝基塑性区扩展等方面综合评价混凝土重力坝极限抗震能力的研究方法。以印度Koyna重力坝为例,采用扩展有限元法(XFEM)模拟了大坝动力破坏过程,数值模拟结果与文献中的模型试验结果基本一致,验证了计算模型的有效性,从基于性能的抗震评价模型及大坝开裂破坏模式评价Koyna重力坝的极限抗震能力为0.40g～0.45g。最后对国内某混凝土重力坝的极限抗震能力进行了探讨和研究,根据大坝需求能力比与超应力累积持时、破坏模式、抗滑稳定性及坝基塑性区破坏范围的综合评价结果,初步认为该重力坝的极限抗震能力为0.45g～0.50g。

This paper proposes a comprehensive evaluation method of ultimate aseismic capacity limit of concrete gravity dams by performance-based seismic fortification criterion and theory. This method is conducted for analysis of nonlinear seismic responses by considering demand-capacity ratio, cumulative overstress duration, failure mode, stability, and plastic zone. An extended finite element method （XFEM） is used to analyze the dynamic failure process of the Koyna dam in India, and the numerical simulations are well consistent with the model test results in the literature. This analysis shows aseismic capacity of 0.45g 0.50g. This comprehensive evaluation method is also applied to preliminary analysis of a domestic concrete gravity dam, and its capacity of 0.45g - 0. 50g is obtained.