强震区抽蓄电站沥青混凝土面板堆石坝抗震稳定性分析

Seismic Stability Analysis of Asphalt Concrete Face Rockfill Dam of Pumped Storage Power Station in Strong Earthquake Area

我国西北强震区某拟建抽水蓄能电站上水库采用沥青混凝土面板堆石坝,最大坝高161 m。为分析该坝抗震稳定性,在大坝非线性静力分析基础上,采用改进的等效粘弹性模型和有限元动力时程法等理论,对大坝开展三维有限元地震反应和坝坡抗震稳定性计算。结果表明,大坝在100年1%超越概率的校核地震(地震加速度为0.48g)作用下,坝体及面板的动力反应分布规律合理。其中,坝体顺河向、坝轴向、竖向加速度极值分别为13.93、13.91、13.80 m/s^(2)。考虑静动叠加后,在沥青混凝土面板反弧段的拉应变极值达0.95%,但小于改性沥青混凝土抗拉强度的一般允许值。因此,大坝即使遭遇0.48g的校核地震作用,亦能保持较好的整体安全性,不会出现重大抗震安全事故。

The upper reservoir of a planned pumped storage power station in the strong earthquake zone of northwest China adopts an asphalt concrete faced rockfill dam,with a maximum dam height of 161 m.Based on the nonlinear static analysis,the three-dimensional finite element seismic response and seismic stability calculation of dam are carried out by using equivalent viscoelastic model and dynamic time-history method.The results show that the dynamic response distribution of dam body and face slab is reasonable under the action of check earthquake with 1%exceeding probability(PGA=0.48g)in 100 years.Among them,the extreme values of downstream,axial and vertical accelerations of the dam are 13.93 m/s^(2),13.91 m/s^(2)and 13.80 m/s^(2),respectively.Considering the static and dynamic superposition,the extreme value of tensile strain in the reverse arc section of asphalt concrete slab attains 0.95%,but it is less than the general allowable value of tensile strength of modified asphalt concrete.Therefore,even if the dam encounters the check earthquake(PGA=0.48g),it can maintain good overall safety and there will be no major seismic safety accidents.