乌东德高拱坝极限抗震能力研究

Study of ultimate aseismic capacity of Wudongde high arch dam

乌东德水电站是金沙江下游河段上4个水电梯级的最上游梯级,大坝为265 m高的双曲拱坝。采用非线性有限元法,将拱坝坝体-坝基作为一个整体系统,在考虑坝体横缝影响及无限地基辐射阻尼影响基础上,模拟坝肩控制性滑块各滑裂面在地震作用下张开、滑移的非线性力学行为,研究设计与校核地震作用下大坝的抗震性能,探讨大坝-坝基整体系统在强震作用下的抗震潜力。研究结果表明:设计地震条件下,坝体仅在拱端应力集中区域拉应力超过抗拉强度,压应力则均满足强度要求,坝肩块体稳定,大坝-坝基体系的整体安全性可以保证;校核地震条件下,坝体应力值略有增加,能够满足不溃坝的设防要求;以大坝-坝基代表性的位移、变形量变化曲线的拐点作为评价极限抗震能力的标准,可知拱坝-坝基体系的抗震超载安全系数为2.7,相应的基岩水平向峰值加速度0.729g,拱坝-坝基体系抗剪参数强度储备安全系数为2.0,乌东德高拱坝具备较强的极限抗震能力。

Wudongde hydropower station is the upper cascade of the four cascaded hydropower stations on the Jinsha River lower reaches. The dam is 265 m high double curvature arch dam. Based on nonlinear finite element method, the dam and foundation were considered as a system together to analyze. The contraction joints, radiation damping of infinite foundation and nonlinear behavior of the slide surfaces in abutment wedges were all taken into account. The aseismic safety of strength of dam body and stability of abutment wedges were studied under the design earthquake and check earthquake. The ultimate aseismic capacity of the dam-foundation system was explored as well. The results show that, in the design earthquake, only the tensile stress of the arch end areas exceeds the tensile strength, while the compressive strength is all within the strength, and the abutment wedges are stable;the stress increases a little in the check earthquake and the dam-foundation system won’t break under the check earthquake; with the inflection points in the displacement or deformation curves of the typical points as evaluation criterion, the seismic overloading safety factor of the dam-foundation system can be taken as 2.7; while the corresponding horizontal peak acceleration is 0.729g; and the strength reserve safety coefficient can be taken as 2.0 conservatively, which proves that the Wudongde high arch dam owes strong ultimate aseismic capacity.