三峡大坝巴东地震动力响应分析与强震监测比对研究

Comparative study on seismic response and strong earthquake monitoring of the Three Gorges Dam during the Badong earthquake

在混凝土坝抗震研究中,大坝强震监测与数值模拟的成果相互比对验证分析对于认识大坝抗震特性有着特别重要的意义。本研究采用地震波动反应分析方法,将三峡大坝在2013年巴东5.1级地震的实测自由场强震记录作为输入,开展了不同阻尼比下的大坝地震反应分析,将不同阻尼比下的成果与泄2#坝段坝体不同高程的实际强震监测记录进行比对和分析,一方面证明了考虑辐射阻尼作用的地震波动分析方法能够合理反映大坝的地震响应,另一方面结果也表明对于远小于设计地震水平的较小地震动输入,混凝土坝结构体系的阻尼比应取为5%以下的较小数值。

The comparison and verification of the seismic responses of dams obtained by the monitoring and numerical simulation of a strong earthquake is of particular importance for adequately understanding the seismic performance of dams.In this study,the free-field ground motion recorded at the Three Gorges Dam during the 2013 Badong M5.1 earthquake is taken as seismic input for the dam.Different damping ratios are considered in numerical modeling based on the seismic wave propagation analysis method,and the results are compared with the recorded responses at different elevations of the dam monolith No.2.It’s revealed that a damping ratio for the concrete dam less than 5%is appropriate for small seismic input far less than the design earthquake.It is also proved that seismic wave propagation analysis method considering the radiation damping effect can reasonably model the seismic response of dams.