复杂地形条件下高面板堆石坝动力反应分析

Dynamic response analysis of high CFRD under complex terrain conditions

面板堆石坝具有良好的抗震能力的特性已被数次强震证明,但其动力反应依然是一个值得关心的问题,尤其是在坝高跨入300m级、河谷地形条件较复杂等情况下。采用等价黏弹性模型,对复杂地形(河谷呈不规则"W"形)条件下高面板堆石坝的动力反应进行分析,得出复杂地形条件下混凝土面板堆石坝(CFRD)坝体、面板的动力反应分布较单一地形条件下复杂,但规律基本相同;最大的动力反应加速度发生在坝体最大断面坝顶位置,最大竖向动位移约为坝高的0.3%;受右岸古河床和左岸陡边坡的影响,右岸的轴向和顺河向动力加速度放大倍数大于左岸,垂直向动力加速度放大倍数反之;古河床位置有一个明显的沉降区域。根据分析结果,复杂地形条件下高面板堆石坝的破坏形式主要有下游坝坡失稳破坏、面板拉裂和震陷超标等。最后提出可采取的抗震措施以供讨论。

Several strong earthquakes proved that the concrete face rockfill dam （CFRD） has nicer aseismic behavior; but its dynamic response is still concerned, especially when the dam height comes in the level of 300 m and it is built on complicated valley terrain conditions, etc. Analyzes the dynamic response of CFRD under complicated topographic condition （the shape of valley is irregular W） by using the equivalent viscoelastic model. It is concluded that the dynamic response of CFRD under complicated topographic condition is more complex than under a single topographic condition, but the rules are same. The strongest dynamic response acceleration locates on dam＇s crest of the largest section, the biggest earthquake＇s settlement is about 0.30% of the dam height. Because of the ancient river terraces on the right bank and vertical slope on the left bank, axial and consequent dynamic acceleration magnification on the right bank are greater than on the left bank; but the vertical dynamic acceleration magnification is contrary. There is an obvious displacement area near the ancient river terraces. Under the influence of seism and terrain conditions, the larger net tensile stress appears on the upper panel to the left bank, which may lead to panel cracking damage. According to the results, the failure forms of high CFRD mainly include the downstream dam slope instability, panel cracking and excessive settlement. Finally, some viable aseismic measures are discussed.